WorldWideScience

Sample records for plants ecosystem stability

  1. Plant ecology. Anthropogenic environmental changes affect ecosystem stability via biodiversity.

    Science.gov (United States)

    Hautier, Yann; Tilman, David; Isbell, Forest; Seabloom, Eric W; Borer, Elizabeth T; Reich, Peter B

    2015-04-17

    Human-driven environmental changes may simultaneously affect the biodiversity, productivity, and stability of Earth's ecosystems, but there is no consensus on the causal relationships linking these variables. Data from 12 multiyear experiments that manipulate important anthropogenic drivers, including plant diversity, nitrogen, carbon dioxide, fire, herbivory, and water, show that each driver influences ecosystem productivity. However, the stability of ecosystem productivity is only changed by those drivers that alter biodiversity, with a given decrease in plant species numbers leading to a quantitatively similar decrease in ecosystem stability regardless of which driver caused the biodiversity loss. These results suggest that changes in biodiversity caused by drivers of environmental change may be a major factor determining how global environmental changes affect ecosystem stability.

  2. Plant Species Diversity Mediates Ecosystem Stability of Natural Dune Grasslands in Response to Drought

    NARCIS (Netherlands)

    Rooijen, van Nils M.; Keersmaecker, de Wanda; Ozinga, Wim A.; Coppin, Pol; Hennekens, Stephan M.; Schaminée, Joop H.J.; Somers, Ben; Honnay, Olivier

    2015-01-01

    How plant species diversity can mediate the temporal stability of ecosystem functioning during periods of environmental stress is still a pressing question in ecology, certainly in the context of predicted increasing frequencies and intensities of climate extremes, such as drought. The vast major

  3. Vegetation component of geothermal EIS studies: Introduced plants, ecosystem stability, and geothermal development

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1994-10-01

    This paper contributes new information about the impacts from introduced plant invasions on the native Hawaiian vegetation as consequences of land disturbance and geothermal development activities. In this regard, most geothermal development is expected to act as another recurring source of physical disturbance which favors the spread and maintenance of introduced organisms throughout the region. Where geothermal exploration and development activities extend beyond existing agricultural and residential development, they will become the initial or sole source of disturbance to the naturalized vegetation of the area. Kilauea has a unique ecosystem adapted to the dynamics of a volcanically active landscape. The characteristics of this ecosystem need to be realized in order to understand the major threats to the ecosystem and to evaluate the effects of and mitigation for geothermal development in Puna. The native Puna vegetation is well adapted to disturbances associated with volcanic eruption, but it is ill-adapted to compete with alien plant species in secondary disturbances produced by human activities. Introduced plant and animal species have become a major threat to the continued presence of the native biota in the Puna region of reference.

  4. Stability measures in arid ecosystems

    Science.gov (United States)

    Nosshi, M. I.; Brunsell, N. A.; Koerner, S.

    2015-12-01

    Stability, the capacity of ecosystems to persist in the face of change, has proven its relevance as a fundamental component of ecological theory. Here, we would like to explore meaningful and quantifiable metrics to define stability, with a focus on highly variable arid and semi-arid savanna ecosystems. Recognizing the importance of a characteristic timescale to any definition of stability, our metrics will be focused scales from annual to multi-annual, capturing different aspects of stability. Our three measures of stability, in increasing order of temporal scale, are: (1) Ecosystem resistance, quantified as the degree to which the system maintains its mean state in response to a perturbation (drought), based on inter-annual variability in Normalized Difference Vegetation Index (NDVI). (2) An optimization approach, relevant to arid systems with pulse dynamics, that models vegetation structure and function based on a trade off between the ability to respond to resource availability and avoid stress. (3) Community resilience, measured as species turnover rate (β diversity). Understanding the nature of stability in structurally-diverse arid ecosystems, which are highly variable, yields theoretical insight which has practical implications.

  5. An Ecohydrological Approach to the Resiliency and Stability of Ecosystems

    Science.gov (United States)

    Peña Alzate, S.; Canon Barriga, J. E.

    2013-12-01

    We introduce a simplified ecohydrological model to quantitatively assess the resiliency and stability of ecosystems. The proposed model couples a hydrological soil moisture balance with a set of spatiotemporal dynamics of systems and agent-based algorithms to represent the interactions among several plant populations in a gridded area under different water, soil and temperature constraints. The model also allows disturbances, representing mostly the effects of deforestation practices. The simulated ecosystem, composed by a set of plant populations, includes allometric rules (i.e., power laws for generational and reproductive times, linear approximations for water and temperature gains, losses and optimal values and a set of intra and interspecific interaction rules based on high, optimal and low competition responses among the populations). Disturbances are determined by a clearance of populations in a defined area within the model's domain. The effects of climate variability can be also incorporated through precipitation and temperature time series that exhibit trends and heteroskedasticity. Resiliency and stability are calculated with modified indices that are used in hydrology, in this case to determine the ability of the ecosystem to recover from a disturbance. The model represents different types of plant phenotypes showing exponential growth in the first steps of the simulations. The indices, evaluated on each population and over the structure of the entire ecosystem, show how different populations respond differently to disturbances, following behaviors similar to those expected in nature, like high reproduction rates on gregarious plants with short generation times, and low densities in plants with high generations times. The selection of plant populations was mainly focused on the concept of biodiversity with emphasis on tropical regions. The model can represent the spatial and temporal succession of the ecosystem after being disturbed. The model also

  6. Stability of alpine meadow ecosystem on the Qinghai- Tibetan Plateau

    Institute of Scientific and Technical Information of China (English)

    ZHOU Huakun; ZHOU Li; ZHAO Xinquan; LIU Wei; LI Yingnian; GU Song; ZHOU Xinmin

    2006-01-01

    The meadow ecosystem on the Qinghai-Tibetan Plateau is considered to be sensitive to climate change. An understanding of the alpine meadow ecosystem is therefore important for predicting the response of ecosystems to climate change. In this study, we use the coefficients of variation (Cv) and stability (E) obtained from the Haibei Alpine Meadow Ecosystem Research Station to characterize the ecosystem stability. The results suggest that the net primary production of the alpine meadow ecosystem was more stable (Cv = 13.18%) than annual precipitation (Cv = 16.55%) and annual mean air temperature (Cv = 28.82%). The net primary production was insensitive to either the precipitation (E = 0.0782) or air temperature (E = 0.1113). In summary, the alpine meadow ecosystem on the Qinghai- Tibetan Plateau is much stable. Comparison of alpine meadow ecosystem stability with other five natural grassland ecosystems in Israel and southern African indicates that the alpine meadow ecosystem on the Qinghai-Tibetan Plateau is the most stable ecosystem. The alpine meadow ecosystem with relatively simple structure has high stability, which indicates that community stability is not only correlated with biodiversity and community complicity but also with environmental stability. An average oscillation cycles of 3―4 years existed in annual precipitation, annual mean air temperature, net primary production and the population size of consumers at the Haibei natural ecosystem. The high stability of the alpine meadow ecosystem may be resulting also from the adaptation of the ecosystem to the alpine environment.

  7. Plant biodiversity impacts on soil stability

    Science.gov (United States)

    Gould, Iain; Quinton, John; Bardgett, Richard

    2014-05-01

    In recent times, growing threats to global biodiversity have raised awareness from the scientific community, with particular interest on how plant diversity impacts on ecosystem functioning. In the field of plant-soil interactions, much work has been done to research the implications of species loss, primarily focussing on biological processes such as plant productivity, microbial activity and carbon cycling. Consequently, virtually nothing is known about how plant diversity might impact on soil physical properties, and what mechanisms might be involved. This represents a serious gap in knowledge, given that maintaining soils with good structural integrity can reduce soil erosion and water pollution, and can lead to improved plant yield. Therefore, there is a need for a greater understanding of how plant communities and ecological interactions between plant roots and soils can play a role in regulating soil physical structure. Soil aggregation is an important process in determining soil stability by regulating soil water infiltration and having consequences for erodibility. This is influenced by both soil physical constituents and biological activity; including soil organic carbon content, microbial growth, and increased plant rooting. As previously mentioned, plant diversity influences carbon dynamics, microbial activity and plant growth, therefore could have substantial consequences for soil aggregate stability. Here, we present results from a series of plant manipulation experiments, on a range of scales, to understand more about how plant diversity could impact on soil aggregate stability. Soils from both a plant manipulation mesocosm experiment, and a long term biodiversity field study, were analysed using the Le Bissonnais method of aggregate stability breakdown. Increasing plant species richness was found to have a significant positive impact on soil aggregate stability at both scales. In addition to this, the influence of species identity, functional group

  8. Stability and Complexity in Digital Ecosystems

    OpenAIRE

    Krause, PJ; Razavi, AR; Moschoyiannis, S.; Marinos, A

    2009-01-01

    In this paper we explore the concept of ldquoecosystemrdquo as a metaphor in the development of the digital economy. We argue that the modelling of social ecosystems as self-organising systems is also relevant to the study of digital ecosystems. Specifically, that centralised control structures in digital ecosystems militate against emergence of innovation and adaptive response to pressures or shocks that may impact the ecosystem. We hope the paper will stimulate a more holistic approach to g...

  9. Genetically modified soybean plants and their ecosystem

    Directory of Open Access Journals (Sweden)

    Milošević Mirjana B.

    2004-01-01

    Full Text Available Transgenic plants are developed by introgressing new genes using methods of molecular genetics and genetic engineering. The presence of these genes in plant genome is identified on the basis of specific oligonucleotides primers, and the use of PCR (Polymerase Chain Reaction and DNA fragments multiplication. Genetically modified plants such as soybean constitute a newly created bioenergetic potential whose gene expression can cause disturbance of the biological balance ecosystem, soil structure and soil microbiological activity. Genetically modified plants may acquire monogenic or polygenic traits causing genetic and physiological changes in these plants, which may elicit a certain reaction of the environment including changes of microbiological composition of soil rhizosphere. The aim of introgressing genes for certain traits into a cultivated plant is to enhance its yield and intensify food production. There are more and more genetically modified plant species such as soybean, corn, potato, rice and others and there is a pressure to use them as human food and animal feed. Genetically modified soybean plants with introgressed gene for resistance to total herbicides, such as Round-up, are more productive than non-modified herbicide-sensitive soybeans.

  10. Ecological behavior and effects of energy related pollutants. Progress report, June 1976--August 1977. [SO2 impact on survival and stability of plant species; fallout /sup 137/Cs transfer processes in Southeastern Coastal Plain ecosystem

    Energy Technology Data Exchange (ETDEWEB)

    Platt, R.B.; Ragsdale, H.L.; Murdy, W.H.; Shure, D.J.

    1977-10-25

    The impact of SO/sub 2/ on the survival and stability of plant populations and communities was studied. The results to date have an important bearing on the adequacy of current permissible ambient air levels for SO/sub 2/. Atmospheric SO/sub 2/ concentrations at near permissible levels had a significant adverse effect on sexual reproduction processes, which results in a reduced number of viable seeds, in all 8 populations tested. Implications for both natural and agricultural plant species and possible significant losses of fruit production are discussed. An ecological implication of the invisible effect of fruit and seed mortality is postulated since the life cycle of many insects and the trophic relations of numerous animals depend, at least in part, on fruit production by trees and shrubs. Hence, there is a potential for disruptive effects on ecosystem level processes. Results are also reported from four systems-oriented studies within the Lower Three Runs Creek Watershed, Savannah River Plant, to examine fallout /sup 137/Cs transfer processes in ecological systems characteristic of the Southeastern Coastal Plain. These studies were carried out within the stream and its floodplains, within floodplains along the stream gradient, in upland aquatic systems (Carolina Bays), and in the upland scrub-oak forest system. Results are discussed.

  11. N-dimensional hypervolumes to study stability of complex ecosystems.

    Science.gov (United States)

    Barros, Ceres; Thuiller, Wilfried; Georges, Damien; Boulangeat, Isabelle; Münkemüller, Tamara

    2016-07-01

    Although our knowledge on the stabilising role of biodiversity and on how it is affected by perturbations has greatly improved, we still lack a comprehensive view on ecosystem stability that is transversal to different habitats and perturbations. Hence, we propose a framework that takes advantage of the multiplicity of components of an ecosystem and their contribution to stability. Ecosystem components can range from species or functional groups, to different functional traits, or even the cover of different habitats in a landscape mosaic. We make use of n-dimensional hypervolumes to define ecosystem states and assess how much they shift after environmental changes have occurred. We demonstrate the value of this framework with a study case on the effects of environmental change on Alpine ecosystems. Our results highlight the importance of a multidimensional approach when studying ecosystem stability and show that our framework is flexible enough to be applied to different types of ecosystem components, which can have important implications for the study of ecosystem stability and transient dynamics. © 2016 John Wiley & Sons Ltd/CNRS.

  12. Plant functional traits predict green roof ecosystem services.

    Science.gov (United States)

    Lundholm, Jeremy; Tran, Stephanie; Gebert, Luke

    2015-02-17

    Plants make important contributions to the services provided by engineered ecosystems such as green roofs. Ecologists use plant species traits as generic predictors of geographical distribution, interactions with other species, and ecosystem functioning, but this approach has been little used to optimize engineered ecosystems. Four plant species traits (height, individual leaf area, specific leaf area, and leaf dry matter content) were evaluated as predictors of ecosystem properties and services in a modular green roof system planted with 21 species. Six indicators of ecosystem services, incorporating thermal, hydrological, water quality, and carbon sequestration functions, were predicted by the four plant traits directly or indirectly via their effects on aggregate ecosystem properties, including canopy density and albedo. Species average height and specific leaf area were the most useful traits, predicting several services via effects on canopy density or growth rate. This study demonstrates that easily measured plant traits can be used to select species to optimize green roof performance across multiple key services.

  13. Biodiversity and ecosystem stability across scales in metacommunities.

    Science.gov (United States)

    Wang, Shaopeng; Loreau, Michel

    2016-05-01

    Although diversity-stability relationships have been extensively studied in local ecosystems, the global biodiversity crisis calls for an improved understanding of these relationships in a spatial context. Here, we use a dynamical model of competitive metacommunities to study the relationships between species diversity and ecosystem variability across scales. We derive analytic relationships under a limiting case; these results are extended to more general cases with numerical simulations. Our model shows that, while alpha diversity decreases local ecosystem variability, beta diversity generally contributes to increasing spatial asynchrony among local ecosystems. Consequently, both alpha and beta diversity provide stabilising effects for regional ecosystems, through local and spatial insurance effects respectively. We further show that at the regional scale, the stabilising effect of biodiversity increases as spatial environmental correlation increases. Our findings have important implications for understanding the interactive effects of global environmental changes (e.g. environmental homogenisation) and biodiversity loss on ecosystem sustainability at large scales.

  14. Climate change effects on plant disease: Genomes to ecosystems

    OpenAIRE

    Garrett, Karen A.; Dendy, S.P.; Frank, E.E.; Rouse, M. N.; Travers, S.E.

    2006-01-01

    We have reviewed the potential effects of climate change on plant disease, considering processes within plants as well as larger scale processes. LTRA-4 (Practices and Strategies for Vulnerable Agro-Ecosystems)

  15. Climate change effects on plant disease: Genomes to ecosystems

    OpenAIRE

    Garrett, Karen A.; Dendy, S.P.; Frank, E.E.; Rouse, M. N.; Travers, S.E.

    2006-01-01

    We have reviewed the potential effects of climate change on plant disease, considering processes within plants as well as larger scale processes. LTRA-4 (Practices and Strategies for Vulnerable Agro-Ecosystems)

  16. Resilience and stability of a pelagic marine ecosystem.

    Science.gov (United States)

    Lindegren, Martin; Checkley, David M; Ohman, Mark D; Koslow, J Anthony; Goericke, Ralf

    2016-01-13

    The accelerating loss of biodiversity and ecosystem services worldwide has accentuated a long-standing debate on the role of diversity in stabilizing ecological communities and has given rise to a field of research on biodiversity and ecosystem functioning (BEF). Although broad consensus has been reached regarding the positive BEF relationship, a number of important challenges remain unanswered. These primarily concern the underlying mechanisms by which diversity increases resilience and community stability, particularly the relative importance of statistical averaging and functional complementarity. Our understanding of these mechanisms relies heavily on theoretical and experimental studies, yet the degree to which theory adequately explains the dynamics and stability of natural ecosystems is largely unknown, especially in marine ecosystems. Using modelling and a unique 60-year dataset covering multiple trophic levels, we show that the pronounced multi-decadal variability of the Southern California Current System (SCCS) does not represent fundamental changes in ecosystem functioning, but a linear response to key environmental drivers channelled through bottom-up and physical control. Furthermore, we show strong temporal asynchrony between key species or functional groups within multiple trophic levels caused by opposite responses to these drivers. We argue that functional complementarity is the primary mechanism reducing community variability and promoting resilience and stability in the SCCS.

  17. CO2 and fire influence tropical ecosystem stability in response to climate change

    Science.gov (United States)

    Shanahan, Timothy M.; Hughen, Konrad A.; McKay, Nicholas P.; Overpeck, Jonathan T.; Scholz, Christopher A.; Gosling, William D.; Miller, Charlotte S.; Peck, John A.; King, John W.; Heil, Clifford W.

    2016-07-01

    Interactions between climate, fire and CO2 are believed to play a crucial role in controlling the distributions of tropical woodlands and savannas, but our understanding of these processes is limited by the paucity of data from undisturbed tropical ecosystems. Here we use a 28,000-year integrated record of vegetation, climate and fire from West Africa to examine the role of these interactions on tropical ecosystem stability. We find that increased aridity between 28–15 kyr B.P. led to the widespread expansion of tropical grasslands, but that frequent fires and low CO2 played a crucial role in stabilizing these ecosystems, even as humidity changed. This resulted in an unstable ecosystem state, which transitioned abruptly from grassland to woodlands as gradual changes in CO2 and fire shifted the balance in favor of woody plants. Since then, high atmospheric CO2 has stabilized tropical forests by promoting woody plant growth, despite increased aridity. Our results indicate that the interactions between climate, CO2 and fire can make tropical ecosystems more resilient to change, but that these systems are dynamically unstable and potentially susceptible to abrupt shifts between woodland and grassland dominated states in the future.

  18. Contrasting tropical estuarine ecosystem functioning and stability: A comparative study

    Science.gov (United States)

    Villanueva, Maria Ching

    2015-03-01

    A comparative study of the Sine-saloum (Senegal) and Gambia (The Gambia) estuaries was performed based on trophic model outputs that describe the system structure and functioning. These trophic models were constructed such as to differentiate main energetic flows in the systems and express how climate change may have impacted ecosystem resilience to change. Estuarine fish assemblages are highly resilient despite exposure to vast hydrodynamic variations and stress. Coupled with strong anthropogenic-driven stresses such as fisheries and climate change, ecosystems may undergo severe regime shifts that may weaken their resilience and stability. Taxonomically related and morphologically similar species do not necessarily play similar ecological roles in these two ecosystems. Biomass and production in the Sine-saloum are concentrated at trophic levels (TLs) 2 and 3, while for the Gambia, both are concentrated at TL3. Higher TL biomasses in Gambia compared to Sine-Saloum may be explained by the latter ecosystem being characterized by inverse hypersalinity. Higher TL of production in Sine-Saloum is due to higher exploitations compared to Gambia where fishing activities are still less developed. High production and consumption rates of some groups in both ecosystems indicate high system productivity. Elevated productivity may be due to higher abundance of juvenile fishes in most groups that utilize the latter as refuge and/or nursery zones. Both ecosystems are phytoplankton-driven. Differences in group trophic and ecological roles are mainly due to adaptive responses of these species to seasonal and long-term climate and anthropogenic stressors. System indicators suggest different levels of ecosystem resilience and stability as a function of biodiversity. Relevance of other observations on ecosystem functioning and indicators in relation to perturbation is discussed.

  19. Ecosystem simplification, biodiversity loss and plant virus emergence.

    Science.gov (United States)

    Roossinck, Marilyn J; García-Arenal, Fernando

    2015-02-01

    Plant viruses can emerge into crops from wild plant hosts, or conversely from domestic (crop) plants into wild hosts. Changes in ecosystems, including loss of biodiversity and increases in managed croplands, can impact the emergence of plant virus disease. Although data are limited, in general the loss of biodiversity is thought to contribute to disease emergence. More in-depth studies have been done for human viruses, but studies with plant viruses suggest similar patterns, and indicate that simplification of ecosystems through increased human management may increase the emergence of viral diseases in crops.

  20. Ecosystem development in roadside grasslands: Biotic control, plant-soil interactions, and dispersal limitations

    Science.gov (United States)

    Garcia-Palacios, P.; Bowker, M.A.; Maestre, F.T.; Soliveres, S.; Valladares, F.; Papadopoulos, J.; Escudero, A.

    2011-01-01

    Roadside grasslands undergoing secondary succession are abundant, and represent ecologically meaningful examples of novel, human-created ecosystems. Interactions between plant and soil communities (hereafter plant-soil interactions) are of major importance in understanding the role of biotic control in ecosystem functioning, but little is known about these links in the context of ecosystem restoration and succession. The assessment of the key biotic communities and interactions driving ecosystem development will help practitioners to better allocate the limited resources devoted to roadside grassland restoration. We surveyed roadside grasslands from three successional stages (0-2, 7-9, and > 20 years) in two Mediterranean regions of Spain. Structural equation modeling was used to evaluate how interactions between plants, biological soil crusts (BSCs), and soil microbial functional diversity (soil microorganisms) affect indicators of ecosystem development and restoration: plant similarity to the reference ecosystem, erosion control, and soil C storage and N accumulation. Changes in plant community composition along the successional gradient exerted the strongest influence on these indicators. High BSC cover was associated with high soil stability, and high soil microbial functional diversity from late-successional stages was associated with high soil fertility. Contrary to our expectations, the indirect effects of plants, mediated by either BSCs or soil microorganisms, were very weak in both regions, suggesting a minor role for plant-soil interactions upon ecosystem development indicators over long periods. Our results suggest that natural vegetation dynamics effectively improved ecosystem development within a time frame of 20 years in the grasslands evaluated. They also indicate that this time could be shortened if management actions focus on: (1) maintaining wellconserved natural areas close to roadsides to enhance plant compositional changes towards late

  1. Functional complexity and ecosystem stability: an experimental approach

    Energy Technology Data Exchange (ETDEWEB)

    Van Voris, P.; O' Neill, R.V.; Shugart, H.H.; Emanuel, W.R.

    1978-01-01

    The complexity-stability hypothesis was experimentally tested using intact terrestrial microcosms. Functional complexity was defined as the number and significance of component interactions (i.e., population interactions, physical-chemical reactions, biological turnover rates) influenced by nonlinearities, feedbacks, and time delays. It was postulated that functional complexity could be nondestructively measured through analysis of a signal generated from the system. Power spectral analysis of hourly CO/sub 2/ efflux, from eleven old-field microcosms, was analyzed for the number of low frequency peaks and used to rank the functional complexity of each system. Ranking of ecosystem stability was based on the capacity of the system to retain essential nutrients and was measured by net loss of Ca after the system was stressed. Rank correlation supported the hypothesis that increasing ecosystem functional complexity leads to increasing ecosystem stability. The results indicated that complex functional dynamics can serve to stabilize the system. The results also demonstrated that microcosms are useful tools for system-level investigations.

  2. Herbivore regulation of plant abundance in aquatic ecosystems.

    Science.gov (United States)

    Wood, Kevin A; O'Hare, Matthew T; McDonald, Claire; Searle, Kate R; Daunt, Francis; Stillman, Richard A

    2017-05-01

    Herbivory is a fundamental process that controls primary producer abundance and regulates energy and nutrient flows to higher trophic levels. Despite the recent proliferation of small-scale studies on herbivore effects on aquatic plants, there remains limited understanding of the factors that control consumer regulation of vascular plants in aquatic ecosystems. Our current knowledge of the regulation of primary producers has hindered efforts to understand the structure and functioning of aquatic ecosystems, and to manage such ecosystems effectively. We conducted a global meta-analysis of the outcomes of plant-herbivore interactions using a data set comprised of 326 values from 163 studies, in order to test two mechanistic hypotheses: first, that greater negative changes in plant abundance would be associated with higher herbivore biomass densities; second, that the magnitude of changes in plant abundance would vary with herbivore taxonomic identity. We found evidence that plant abundance declined with increased herbivore density, with plants eliminated at high densities. Significant between-taxa differences in impact were detected, with insects associated with smaller reductions in plant abundance than all other taxa. Similarly, birds caused smaller reductions in plant abundance than echinoderms, fish, or molluscs. Furthermore, larger reductions in plant abundance were detected for fish relative to crustaceans. We found a positive relationship between herbivore species richness and change in plant abundance, with the strongest reductions in plant abundance reported for low herbivore species richness, suggesting that greater herbivore diversity may protect against large reductions in plant abundance. Finally, we found that herbivore-plant nativeness was a key factor affecting the magnitude of herbivore impacts on plant abundance across a wide range of species assemblages. Assemblages comprised of invasive herbivores and native plant assemblages were associated with

  3. Functional Diversity of Boreal Bog Plant Species Decreases Seasonal Variation of Ecosystem Carbon Sink Function

    Science.gov (United States)

    Korrensalo, A.

    2015-12-01

    Species diversity has been found to decrease the temporal variance of productivity of a plant community, and diversity in species responses to environmental factors seems to make a plant community more stable in changing conditions. Boreal bogs are nutrient poor peatland ecosystems where the number of plant species is low but the species differ greatly in their growth form. In here we aim to assess the role of the variation in photosynthesis between species for the temporal variation in ecosystem carbon sink function. To quantify the photosynthetic properties and their seasonal variation for different bog plant species we measured photosynthetic parameters and stress-inducing chlorophyll fluorescence of vascular plant and Sphagnum moss species in a boreal bog over a growing season. We estimated monthly gross photosynthesis (PG) of the whole study site based on species level light response curves and leaf area development. The estimated PG was further compared with a gross primary production (GPP) estimate measured by eddy covariance (EC) technique. The sum of upscaled PG estimates agreed well with the GPP estimate measured by the EC technique. The contributions of the species and species groups to the ecosystem level PG changed over the growing season. The sharp mid-summer peak in sedge PG was balanced by more stable PG of evergreen shrubs and Sphagna. Species abundance rather than differences in photosynthetic properties between species and growth forms determined the most productive plants on the ecosystem scale. Sphagna had lower photosynthesis and clorophyll fluorescence than vascular plants but were more productive on the ecosystem scale throughout the growing season due to their high areal coverage. These results show that the diversity of growth forms stabilizes the seasonal variation of the ecosystem level PG in an ombrotrophic bog ecosystem. This may increase the resilience of the ecosystem to changing environmental conditions.

  4. Urban ecosystem services: tree diversity and stability of tropospheric ozone removal.

    Science.gov (United States)

    Manes, Fausto; Incerti, Guido; Salvatori, Elisabetta; Vitale, Marcello; Ricotta, Carlo; Costanza, Robert

    2012-01-01

    Urban forests provide important ecosystem services, such as urban air quality improvement by removing pollutants. While robust evidence exists that plant physiology, abundance, and distribution within cities are basic parameters affecting the magnitude and efficiency of air pollution removal, little is known about effects of plant diversity on the stability of this ecosystem service. Here, by means of a spatial analysis integrating system dynamic modeling and geostatistics, we assessed the effects of tree diversity on the removal of tropospheric ozone (O3) in Rome, Italy, in two years (2003 and 2004) that were very different for climatic conditions and ozone levels. Different tree functional groups showed complementary uptake patterns, related to tree physiology and phenology, maintaining a stable community function across different climatic conditions. Our results, although depending on the city-specific conditions of the studied area, suggest a higher function stability at increasing diversity levels in urban ecosystems. In Rome, such ecosystem services, based on published unitary costs of externalities and of mortality associated with O3, can be prudently valued to roughly US$2 and $3 million/year, respectively.

  5. Dew formation characteristics in a revegetation-stabilized desert ecosystem in Shapotou area, Northern China

    Science.gov (United States)

    Pan, Yan-xia; Wang, Xin-ping; Zhang, Ya-feng

    2010-06-01

    SummarySoil moisture in the upper layer plays an important role in arid desert ecosystems. Dew as an additional source of fresh water, may have a positive impact upon the ecosystems in arid and semi-arid zones. Measurements on dew formation amount and duration were carried out in the whole October of 2008 at different condensing surface types (bare dune sands, physical soil crusts and biological soil crusts) associated with different inter-space positions between plants, and at the area under plant canopy in a revegetation-stabilized arid desert ecosystem in Shapotou area, China. The results indicated that there was a positive linear correlation between dew amounts and relative humidity, while mean temperature was negatively linearly related to dew amounts and no significant relationship was found between dew amounts and wind speed. Clear and foggy mornings were characterized by higher dew amounts and longer dew duration, whereas less dew was recorded during cloudy and especially windy mornings. Crusts, especially the biological soil crusts, obtained significantly higher amounts of dew than that of bare moving sand dunes. It was more difficult for dew to condense under the canopy of the plants than on the bare sand dunes. At the first stage of ecological engineering projects, dew can renew the moisture losing through the evaporation of soil and transpiration of leaves, and thus can supply important source of water for xerophytic shrubs. The higher dew amount at the inter-space of re-vegetated plants is an important driving factor for the growth of microorganisms and spore plants, which further accelerate the formation of biological soil crusts and stabilization of moving sand dunes. The presence of biological soil crusts, in turn, helps to facilitate the formation of dew. Therefore, a mutual enhanced effect exists between dew and artificially revegetation ecosystems.

  6. How to measure ecosystem stability? An evaluation of the reliability of stability metrics based on remote sensing time series across the major global ecosystems.

    Science.gov (United States)

    De Keersmaecker, Wanda; Lhermitte, Stef; Honnay, Olivier; Farifteh, Jamshid; Somers, Ben; Coppin, Pol

    2014-07-01

    Increasing frequency of extreme climate events is likely to impose increased stress on ecosystems and to jeopardize the services that ecosystems provide. Therefore, it is of major importance to assess the effects of extreme climate events on the temporal stability (i.e., the resistance, the resilience, and the variance) of ecosystem properties. Most time series of ecosystem properties are, however, affected by varying data characteristics, uncertainties, and noise, which complicate the comparison of ecosystem stability metrics (ESMs) between locations. Therefore, there is a strong need for a more comprehensive understanding regarding the reliability of stability metrics and how they can be used to compare ecosystem stability globally. The objective of this study was to evaluate the performance of temporal ESMs based on time series of the Moderate Resolution Imaging Spectroradiometer derived Normalized Difference Vegetation Index of 15 global land-cover types. We provide a framework (i) to assess the reliability of ESMs in function of data characteristics, uncertainties and noise and (ii) to integrate reliability estimates in future global ecosystem stability studies against climate disturbances. The performance of our framework was tested through (i) a global ecosystem comparison and (ii) an comparison of ecosystem stability in response to the 2003 drought. The results show the influence of data quality on the accuracy of ecosystem stability. White noise, biased noise, and trends have a stronger effect on the accuracy of stability metrics than the length of the time series, temporal resolution, or amount of missing values. Moreover, we demonstrate the importance of integrating reliability estimates to interpret stability metrics within confidence limits. Based on these confidence limits, other studies dealing with specific ecosystem types or locations can be put into context, and a more reliable assessment of ecosystem stability against environmental disturbances

  7. Plant functional traits and diversity in sand dune ecosystems across different biogeographic regions

    Science.gov (United States)

    Mahdavi, P.; Bergmeier, E.

    2016-07-01

    Plant species of a functional group respond similarly to environmental pressures and may be expected to act similarly on ecosystem processes and habitat properties. However, feasibility and applicability of functional groups in ecosystems across very different climatic regions have not yet been studied. In our approach we specified the functional groups in sand dune ecosystems of the Mediterranean, Hyrcanian and Irano-Turanian phytogeographic regions. We examined whether functional groups are more influenced by region or rather by habitat characteristics, and identified trait syndromes associated with common habitat types in sand dunes (mobile dunes, stabilized dunes, salt marshes, semi-wet sands, disturbed habitats). A database of 14 traits, 309 species and 314 relevés was examined and trait-species, trait-plot and species-plot matrices were built. Cluster analysis revealed similar plant functional groups in sand dune ecosystems across regions of very different species composition and climate. Specifically, our study showed that plant traits in sand dune ecosystems are grouped reflecting habitat affiliation rather than region and species pool. Environmental factors and constraints such as sand mobility, soil salinity, water availability, nutrient status and disturbance are more important for the occurrence and distribution of plant functional groups than regional belonging. Each habitat is shown to be equipped with specific functional groups and can be described by specific sets of traits. In restoration ecology the completeness of functional groups and traits in a site may serve as a guideline for maintaining or restoring the habitat.

  8. Climate change effects on plant disease: genomes to ecosystems.

    Science.gov (United States)

    Garrett, K A; Dendy, S P; Frank, E E; Rouse, M N; Travers, S E

    2006-01-01

    Research in the effects of climate change on plant disease continues to be limited, but some striking progress has been made. At the genomic level, advances in technologies for the high-throughput analysis of gene expression have made it possible to begin discriminating responses to different biotic and abiotic stressors and potential trade-offs in responses. At the scale of the individual plant, enough experiments have been performed to begin synthesizing the effects of climate variables on infection rates, though pathosystem-specific characteristics make synthesis challenging. Models of plant disease have now been developed to incorporate more sophisticated climate predictions. At the population level, the adaptive potential of plant and pathogen populations may prove to be one of the most important predictors of the magnitude of climate change effects. Ecosystem ecologists are now addressing the role of plant disease in ecosystem processes and the challenge of scaling up from individual infection probabilities to epidemics and broader impacts.

  9. A review of impacts by invasive exotic plants on forest ecosystem services

    Science.gov (United States)

    Kevin Devine; Songlin. Fei

    2011-01-01

    Many of our forest ecosystems are at risk due to the invasion of exotic invasive plant species. Invasive plant species pose numerous threats to ecosystems by decreasing biodiversity, deteriorating ecosystem processes, and degrading ecosystem services. Literature on Kentucky's most invasive exotic plant species was examined to understand their potential impacts on...

  10. Plant community controls on short-term ecosystem nitrogen retention.

    Science.gov (United States)

    de Vries, Franciska T; Bardgett, Richard D

    2016-05-01

    Retention of nitrogen (N) is a critical ecosystem function, especially in the face of widespread anthropogenic N enrichment; however, our understanding of the mechanisms involved is limited. Here, we tested under glasshouse conditions how plant community attributes, including variations in the dominance, diversity and range of plant functional traits, influence N uptake and retention in temperate grassland. We added a pulse of (15) N to grassland plant communities assembled to represent a range of community-weighted mean plant traits, trait functional diversity and divergence, and species richness, and measured plant and microbial uptake of (15) N, and leaching losses of (15) N, as a short-term test of N retention in the plant-soil system. Root biomass, herb abundance and dominant plant traits were the main determinants of N retention in the plant-soil system: greater root biomass and herb abundance, and lower root tissue density, increased plant (15) N uptake, while higher specific leaf area and root tissue density increased microbial (15) N uptake. Our results provide novel, mechanistic insight into the short-term fate of N in the plant-soil system, and show that dominant plant traits, rather than trait functional diversity, control the fate of added N in the plant-soil system.

  11. Explaining plant-soil diversity in Alpine ecosystems: more than just time since ecosystem succession started

    Science.gov (United States)

    Lane, Stuart; Baetz, Nico; Borgeaud, Laure; Verrecchia, Eric; Vittoz, Pascal

    2014-05-01

    Ecosystem succession in Alpine environments has been a focus of research for many decades. Following from the classic ideas of Jenny (1941, 1961), following perturbation, an ecosystem (flora, fauna and soil) should evolve as a function of time at a rate conditioned by external variables (relief, climate, geology). More recently, biogeomorphologists have focused upon the notion of co-evolution of geomorphic processes with ecosystems over very short through to very long (evolutionary) time-scales. Alpine environments have been a particular focus of models of co-evolution, as a means of understanding the rate of plant colonization of previously glaciated terrain. However, work in this field has tended to adopt an over simplified view of the relationship between perturbation and succession, including: how the landform and ecosystem itself conditions the impact of a perturbation to create a complex spatial impact; and how perturbations are not simply ecosystem destroyers but can be a significant source of ecosystem resources. What this means is that at the within landform scale, there may well be a complex and dynamic topographic and sedimentological template that co-evolves with the development of soil, flora and fauna. In this paper, we present and test conceptual models for such co-evolution for an Alpine alluvial fan and an Alpine piedmont braided river. We combine detailed floristic inventory with soil inventory, survey of edaphic variables above and below ground (e.g. vertical and lateral sedimentological structure, using electrical resistance tomography) and the analysis of historical aerial imagery. The floristic inventory shows the existence of a suite of distinct plant communities within each landform. Time since last perturbation is not a useful explanatory variable of the spatial distribution of these communities because: (1) perturbation impacts are spatially variable, as conditioned by the extent distribution of topographic, edaphic and ecological

  12. Coupling of soil prokaryotic diversity and plant diversity across latitudinal forest ecosystems

    Science.gov (United States)

    Wang, Jun-Tao; Zheng, Yuan-Ming; Hu, Hang-Wei; Li, Jing; Zhang, Li-Mei; Chen, Bao-Dong; Chen, Wei-Ping; He, Ji-Zheng

    2016-01-01

    The belowground soil prokaryotic community plays a cardinal role in sustaining the stability and functions of forest ecosystems. Yet, the nature of how soil prokaryotic diversity co-varies with aboveground plant diversity along a latitudinal gradient remains elusive. By establishing three hundred 400-m2 quadrats from tropical rainforest to boreal forest in a large-scale parallel study on both belowground soil prokaryote and aboveground tree and herb communities, we found that soil prokaryotic diversity couples with the diversity of herbs rather than trees. The diversity of prokaryotes and herbs responds similarly to environmental factors along the latitudinal gradient. These findings revealed that herbs provide a good predictor of belowground biodiversity in forest ecosystems, and provide new perspective on the aboveground and belowground interactions in forest ecosystems.

  13. Plant species richness and ecosystem multifunctionality in global drylands

    Science.gov (United States)

    Maestre, Fernando T.; Quero, Jose L.; Gotelli, Nicholas J.; Escudero, Adrian; Ochoa, Victoria; Delgado-Baquerizo, Manuel; Garcia-Gomez, Miguel; Bowker, Matthew A.; Soliveres, Santiago; Escolar, Cristina; Garcia-Palacios, Pablo; Berdugo, Miguel; Valencia, Enrique; Gozalo, Beatriz; Gallardo, Antonio; Aguilera, Lorgio; Arredondo, Tulio; Blones, Julio; Boeken, Bertrand; Bran, Donaldo; Conceicao, Abel A.; Cabrera, Omar; Chaieb, Mohamed; Derak, Mchich; Eldridge, David J.; Espinosa, Carlos I.; Florentino, Adriana; Gaitan, Juan; Gatica, M. Gabriel; Ghiloufi, Wahida; Gomez-Gonzalez, Susana; Gutie, Julio R.; Hernandez, Rosa M.; Huang, Xuewen; Huber-Sannwald, Elisabeth; Jankju, Mohammad; Miriti, Maria; Monerris, Jorge; Mau, Rebecca L.; Morici, Ernesto; Naseri, Kamal; Ospina, Abelardo; Polo, Vicente; Prina, Anibal; Pucheta, Eduardo; Ramirez-Collantes, David A.; Romao, Roberto; Tighe, Matthew; Torres-Diaz, Cristian; Val, James; Veiga, Jose P.; Wang, Deli; Zaady, Eli

    2012-01-01

    Experiments suggest that biodiversity enhances the ability of ecosystems to maintain multiple functions, such as carbon storage, productivity, and the buildup of nutrient pools (multifunctionality). However, the relationship between biodiversity and multifunctionality has never been assessed globally in natural ecosystems. We report here on a global empirical study relating plant species richness and abiotic factors to multifunctionality in drylands, which collectively cover 41% of Earth's land surface and support over 38% of the human population. Multifunctionality was positively and significantly related to species richness. The best-fitting models accounted for over 55% of the variation in multifunctionality and always included species richness as a predictor variable. Our results suggest that the preservation of plant biodiversity is crucial to buffer negative effects of climate change and desertification in drylands.

  14. Plant rooting strategies in water-limited ecosystems

    Science.gov (United States)

    Collins, D. B. G.; Bras, R. L.

    2007-06-01

    Root depth and distribution are vital components of a plant's strategy for growth and survival in water-limited ecosystems and play significant roles in hydrologic and biogeochemical cycling. Knowledge of root profiles is invaluable in measuring and predicting ecosystem dynamics, yet data on root profiles are difficult to obtain. We developed an ecohydrological model of environmental forcing, soil moisture dynamics, and transpiration to explore dependencies of optimal rooting on edaphic, climatic, and physiological factors in water-limited ecosystems. The analysis considers individual plants with fixed biomass. Results of the optimization approach are consistent with profiles observed in nature. Optimal rooting was progressively deeper, moving from clay to loam, silt and then sand, and in wetter and cooler environments. Climates with the majority of the rainfall in winter produced deeper roots than if the rain fell in summer. Long and infrequent storms also favored deeper rooting. Plants that exhibit water stress at slight soil moisture deficiencies consistently showed deeper optimal root profiles. Silt generated the greatest sensitivity to differences in climatic and physiological parameters. The depth of rooting is governed by the depth to which water infiltrates, as influenced by soil properties and the timing and magnitude of water input and evaporative demand. These results provide a mechanistic illustration of the diversity of rooting strategies in nature.

  15. Engineering a plant community to deliver multiple ecosystem services.

    Science.gov (United States)

    Storkey, Jonathan; Döring, Thomas; Baddeley, John; Collins, Rosemary; Roderick, Stephen; Jones, Hannah; Watson, Christine

    2015-06-01

    The sustainable delivery of multiple ecosystem services requires the management of functionally diverse biological communities. In an agricultural context, an emphasis on food production has often led to a loss of biodiversity to the detriment of other ecosystem services such as the maintenance of soil health and pest regulation. In scenarios where multiple species can be grown together, it may be possible to better balance environmental and agronomic services through the targeted selection of companion species. We used the case study of legume-based cover crops to engineer a plant community that delivered the optimal balance of six ecosystem services: early productivity, regrowth following mowing, weed suppression, support of invertebrates, soil fertility building (measured as yield of following crop), and conservation of nutrients in the soil. An experimental species pool of 12 cultivated legume species was screened for a range of functional traits and ecosystem services at five sites across a geographical gradient in the United Kingdom. All possible species combinations were then analyzed, using a process-based model of plant competition, to identify the community that delivered the best balance of services at each site. In our system, low to intermediate levels of species richness (one to four species) that exploited functional contrasts in growth habit and phenology were identified as being optimal. The optimal solution was determined largely by the number of species and functional diversity represented by the starting species pool, emphasizing the importance of the initial selection of species for the screening experiments. The approach of using relationships between functional traits and ecosystem services to design multifunctional biological communities has the potential to inform the design of agricultural systems that better balance agronomic and environmental services and meet the current objective of European agricultural policy to maintain viable food

  16. Use of Plants for Remediation, Stabilization and Restoration of Aquatic and Terrestrial Ecosystems%植物在修复、固定和重建水生、陆生生态系统中的应用

    Institute of Scientific and Technical Information of China (English)

    Andreas SCHAEFFER; 陈忠礼; Mathias EBEL; Michael EVANGELOU; Henner HOLLERT; Martina ROB-NICKOLL; Burkhard SCHMIDT; 袁野; Gotffried LENNARTZ

    2012-01-01

    植物能够吸收或降解污染物来修复受污染的土壤和水体[1-2],还能固定土壤、泥沙防止侵蚀和污染物从固体介质中释放[3].众多无机和有机污染物都能被对其有耐性且生物量大的植物有效降解.例如,凤眼莲能吸收和净化来自金矿采掘废水的氰化物,这类废水含各种氰化物以及重金属元素的浓度达到导致生物体产生毒性效应的水平.检测表明氰化物对凤眼莲的半数致死剂量(LC50)为13 mg/L,将经过高浓度氰化物废水驯化后的凤眼莲放在野外小型湿地进行试验,结果显示这类植物对氰化物的降解效率更高.放射性同位素试验发现氰化物分子中的C和N原子经过植物代谢合成天冬酰胺,从而将有毒性的氰化物转化为无毒的产物[4].尾矿场也可以用植物来修复,一方面植物可以过滤污染物浓度很高的渗滤液,另一方面栽种植物可以固定边坡减少侵蚀.将高覆盖度植被的概念应用在一个尾矿场上,通过种植北美黄杉使其全年都维持较高的蒸腾效率来减少渗滤液.而边坡的固定首先需要在坡面安置固定、菱形的新鲜柳条编织成的笼状网格,其后覆上土壤并喷播能在生长期对固定土壤发挥作用的草本、灌木以及树木种子.这项技术同样适用于河岸侵蚀防护.%Plants can be used to remediate polluted soil or water (phytoremediation) by extracting and/or degrading pollutants[1-2] and for stabilization of soils and sediments [3] (phytostabilization) in order to prevent erosion and to minimize the release of contaminants from the solid matrix. A broad range of inorganic and organic pollutants can thus be processed by using suitable plants that are tolerant of the pollutants, generate high biomass, and are effective in uptake. As an example, water hyacinths can be used for extracting and degrading cyanide from gold mining process water that usually contains cyanide species and heavy metals in

  17. Landform-water-vegetation feedbacks regulate ecosystem stability and restoration potential in semiarid landscapes

    Science.gov (United States)

    Moreno de las Heras, Mariano; Saco, Patricia; Merino Martin, Luis; Espigares, Tiscar; Nicolau, Jose Manuel

    2016-04-01

    Plant production and vegetation dynamics in drylands are shaped by landform patterns, and largely depends on favorable surface redistribution of runoff and sediments. Similarly, the organization of vegetation in these systems controls runoff generation and erosion, and strongly influences the spatial redistribution of water and soil resources. Landform-water-vegetation feedbacks may have, therefore, a key role determining the stability and restoration potential of arid and semiarid ecosystems. We present a synthesis of field, remotely-sensed and modelling studies on landform-soil-vegetation patterns in semiarid rangelands of Australia and reclaimed coal-mining slopes of Mediterranean-dry Spain. Our results indicate that the organization and stability of vegetation patterns strongly depends on feedbacks with coevolving landforms. Exploration of banded woodlands in central Australia reveals that disturbances (e.g. grazing, wildfires) can impact landform-water-vegetation feedbacks, altering the way water is spatially redistributed and used by vegetation, which results in non-linear reductions of ecosystem function. Successful experiences on the restoration of these systems suggest that the spatial management of runoff and sediments is decisive to rehabilitate vegetation patchiness and landscape function. The study of vegetation-water-landform feedbacks in Mediterranean-dry reclaimed mining slopes of Spain offers additional indications on the restoration of drylands, particularly on the effects of rill and gully erosion on the stability of restored vegetation. The development of rill and gully networks provides very efficient drainage networks for the routing of runoff and sediments that drastically reduce the availability of water and soil resources for plant production, ultimately causing degradation of vegetation and restoration failure. This work is supported by a Beatriu de Pinós fellowship co-funded by the European Commission and the Generalitat de Catalunya

  18. Linking land-use intensification, plant communities, and ecosystem processes in lowland Bolivia

    OpenAIRE

    Carreno Rocabado, I.G.

    2013-01-01

    Land-use intensification (LUI) is one of the main global drivers of biodiversity loss with negative impact on ecosystem processes and the services that societies derive from the ecosystems. The effect of LUI on ecosystem processes can be direct through changes in environmental conditions and indirect through changes in plant community. In this dissertation I explored the mechanisms through which land-use intensification affects plant community assembly and ecosystem processes in the Bolivian ...

  19. The imprint of plants on ecosystem functioning: A data-driven approach

    Science.gov (United States)

    Musavi, Talie; Mahecha, Miguel D.; Migliavacca, Mirco; Reichstein, Markus; van de Weg, Martine Janet; van Bodegom, Peter M.; Bahn, Michael; Wirth, Christian; Reich, Peter B.; Schrodt, Franziska; Kattge, Jens

    2015-12-01

    Terrestrial ecosystems strongly determine the exchange of carbon, water and energy between the biosphere and atmosphere. These exchanges are influenced by environmental conditions (e.g., local meteorology, soils), but generally mediated by organisms. Often, mathematical descriptions of these processes are implemented in terrestrial biosphere models. Model implementations of this kind should be evaluated by empirical analyses of relationships between observed patterns of ecosystem functioning, vegetation structure, plant traits, and environmental conditions. However, the question of how to describe the imprint of plants on ecosystem functioning based on observations has not yet been systematically investigated. One approach might be to identify and quantify functional attributes or responsiveness of ecosystems (often very short-term in nature) that contribute to the long-term (i.e., annual but also seasonal or daily) metrics commonly in use. Here we define these patterns as "ecosystem functional properties", or EFPs. Such as the ecosystem capacity of carbon assimilation or the maximum light use efficiency of an ecosystem. While EFPs should be directly derivable from flux measurements at the ecosystem level, we posit that these inherently include the influence of specific plant traits and their local heterogeneity. We present different options of upscaling in situ measured plant traits to the ecosystem level (ecosystem vegetation properties - EVPs) and provide examples of empirical analyses on plants' imprint on ecosystem functioning by combining in situ measured plant traits and ecosystem flux measurements. Finally, we discuss how recent advances in remote sensing contribute to this framework.

  20. Soil ecosystem functioning under climate change: plant species and community effects.

    Science.gov (United States)

    Kardol, Paul; Cregger, Melissa A; Campany, Courtney E; Classen, Aimee T

    2010-03-01

    Feedbacks of terrestrial ecosystems to atmospheric and climate change depend on soil ecosystem dynamics. Soil ecosystems can directly and indirectly respond to climate change. For example, warming directly alters microbial communities by increasing their activity. Climate change may also alter plant community composition, thus indirectly altering the soil communities that depend on their inputs. To better understand how climate change may directly and indirectly alter soil ecosystem functioning, we investigated old-field plant community and soil ecosystem responses to single and combined effects of elevated [CO2], warming, and precipitation in Tennessee (USA). Specifically, we collected soils at the plot level (plant community soils) and beneath dominant plant species (plant-specific soils). We used microbial enzyme activities and soil nematodes as indicators for soil ecosystem functioning. Our study resulted in two main findings: (1) Overall, while there were some interactions, water, relative to increases in [CO2] and warming, had the largest impact on plant community composition, soil enzyme activity, and soil nematodes. Multiple climate-change factors can interact to shape ecosystems, but in our study, those interactions were largely driven by changes in water. (2) Indirect effects of climate change, via changes in plant communities, had a significant impact on soil ecosystem functioning, and this impact was not obvious when looking at plant community soils. Climate-change effects on enzyme activities and soil nematode abundance and community structure strongly differed between plant community soils and plant-specific soils, but also within plant-specific soils. These results indicate that accurate assessments of climate-change impacts on soil ecosystem functioning require incorporating the concurrent changes in plant function and plant community composition. Climate-change-induced shifts in plant community composition will likely modify or counteract the

  1. Soil ecosystem functioning under climate change: plant species and community effects

    Energy Technology Data Exchange (ETDEWEB)

    Kardol, Paul [ORNL; Cregger, Melissa [ORNL; Campany, Courtney E [ORNL; Classen, Aimee T [ORNL

    2010-01-01

    Feedbacks of terrestrial ecosystems to climate change depend on soil ecosystem dynamics. Soil ecosystems can directly and indirectly respond to climate change. For example, warming directly alters microbial communities by increasing their activity. Climate change may also alter plant community composition, thus indirectly altering the microbial communities that feed on their inputs. To better understand how climate change may directly and indirectly alter soil ecosystem functioning, we investigated old-field plant community and soil ecosystem responses to single and combined effects of elevated [CO2], warming, and water availability. Specifically, we collected soils at the plot level (plant community soils), and beneath dominant plant species (plant-specific soils). We used microbial enzyme activities and soil nematodes as indicators for soil ecosystem functioning. Our study resulted in two main findings: 1) Overall, while there were some interactions, water, relative to increases in [CO2] and warming, had the largest impact on plant community composition, soil enzyme activities, and soil nematodes. Multiple climate change factors can interact to shape ecosystems, but in this case, those interactions were largely driven by changes in water availability. 2) Indirect effects of climate change, via changes in plant communities, had a significant impact on soil ecosystem functioning and this impact was not obvious when looking at plant community soils. Climate change effects on enzyme activities and soil nematode abundance and community structure strongly differed between plant community soils and plant-specific soils, but also within plant-specific soils. In sum, these results indicate that accurate assessments of climate change impacts on soil ecosystem functioning require incorporating the concurrent changes in plant function and plant community composition. Climate change-induced shifts in plant community composition will likely modify or counteract the direct

  2. Plant functional traits, functional diversity, and ecosystem functioning: current knowledge and perspectives

    Directory of Open Access Journals (Sweden)

    Lingjie Lei

    2016-08-01

    Full Text Available Increasing attention has recently been focused on the linkages between plant functional traits and ecosystem functioning. A comprehensive understanding of these linkages can facilitate to address the ecological consequences of plant species loss induced by human activities and climate change, and provide theoretical support for ecological restoration and ecosystem management. In recent twenty years, the evidence of strong correlations between plant functional traits and changes in ecosystem processes is growing. More importantly, ecosystem functioning can be predicted more precisely, using plant functional trait diversity (i.e., functional diversity than species diversity. In this paper, we first defined plant functional traits and their important roles in determining ecosystem processes. Then, we review recent advances in the relationships between ecosystem functions and plant functional traits and their diversity. Finally, we propose several important future research directions, including (1 exploration of the relationships between aboveground and belowground plant traits and their roles in determining ecosystem functioning, (2 incorporation of the impacts of consumer and global environmental change into the correlation between plant functional traits and ecosystem functioning, (3 effects of functional diversity on ecosystem multifunctionality, and (4 examination of the functional diversity-ecosystem functioning relationship at different temporal and spatial scales.

  3. On the generality of stability-complexity relationships in Lotka-Volterra ecosystems.

    Science.gov (United States)

    Townsend, Sunny E; Haydon, Daniel T; Matthews, Louise

    2010-11-21

    Understanding how complexity persists in nature is a long-standing goal of ecologists. In theoretical ecology, local stability is a widely used measure of ecosystem persistence and has made a major contribution to the ecosystem stability-complexity debate over the last few decades. However, permanence is coming to be regarded as a more satisfactory definition of ecosystem persistence and has relatively recently become available as a tool for assessing the global stability of Lotka-Volterra communities. Here we document positive relationships between permanence and Lotka-Volterra food web complexity and report a positive correlation between the probability of local stability and permanence. We investigate further the frequency of discrepancy (attributed to fragile systems that are locally stable but not permanent or locally unstable systems that are permanent and have cyclic or chaotic dynamics), associate non-permanence with the local stability or instability of equilibria on the boundary of the state-space, and investigate how these vary with aspects of ecosystem complexity. We find that locally stable interior equilibria tend to have all locally unstable boundary equilibria. Since a locally stable boundary is inconsistent with permanent dynamics, this can explain the observed positive correlation between local interior stability and permanence. Our key finding is that, at least in Lotka-Volterra model ecosystems, local stability may be a better measure of persistence than previously thought. Copyright © 2010 Elsevier Ltd. All rights reserved.

  4. Fungal life-styles and ecosystem dynamics: biological aspects of plant pathogens, plant endophytes and saprophytes

    Science.gov (United States)

    Rodriguez, R.J.; Redman, R.S.

    1997-01-01

    This chapter discusses various biochemical, genetic, ecological, and evolutionary aspects of fungi that express either symbiotic or saprophytic life-styles. An enormous pool of potential pathogens exists in both agricultural and natural ecosystems, and virtually all plant species are susceptible to one or more fungal pathogens. Fungal pathogens have the potential to impact on the genetic structure of populations of individual plant species, the composition of plant communities and the process of plant succession. Endophytic fungi exist for at least part of their life cycles within the tissues of a plant host. This group of fungi is distinguished from plant pathogens because they do not elicit significant disease symptoms. However, endophytes do maintain the genetic and biochemical mechanisms required for infection and colonization of plant hosts. Fungi that obtain chemical nutrients from dead organic matter are known as saprophytes and are critical to the dynamics and resilience of ecosystems. There are two modes of saprophytic growth: one in which biomolecules that are amenable to transport across cell walls and membranes are directly absorbed, and another in which fungi must actively convert complex biopolymers into subunit forms amenable to transportation into cells. Regardless of life-style, fungi employ similar biochemical mechanisms for the acquisition and conversion of nutrients into complex biomolecules that are necessary for vegetative growth, production and dissemination of progeny, organismal competition, and survival during periods of nutrient deprivation or environmental inclemency.

  5. A Non-equilibrium Thermodynamic Framework for the Dynamics and Stability of Ecosystems

    CERN Document Server

    Michaelian, K

    2002-01-01

    The population dynamics and stability of ecosystems of interacting species is studied from the perspective of non-equilibrium thermodynamics by assuming that species, through their biotic and abiotic interactions, are units of entropy production and exchange in an open thermodynamic system with constant external constraints. Within the context of the linear theory of irreversible thermodynamics, such a system will naturally evolve towards a stable stationary state in which the production of entropy within the ecosystem is at a local minimum value. It is shown that this extremal condition leads to equations for the stationary (steady) state population dynamics of interacting species, more general than those of Lotka-Volterra, and to conditions on the parameters of the community interaction matrix guaranteeing ecosystem stability. The paradoxical stability of real complex ecosystems thus has a simple explanation within the proposed framework. Furthermore, it is shown that the second law of thermodynamics constr...

  6. Wind Power Plant Voltage Stability Evaluation: Preprint

    Energy Technology Data Exchange (ETDEWEB)

    Muljadi, E.; Zhang, Y. C.

    2014-09-01

    Voltage stability refers to the ability of a power system to maintain steady voltages at all buses in the system after being subjected to a disturbance from a given initial operating condition. Voltage stability depends on a power system's ability to maintain and/or restore equilibrium between load demand and supply. Instability that may result occurs in the form of a progressive fall or rise of voltages of some buses. Possible outcomes of voltage instability are the loss of load in an area or tripped transmission lines and other elements by their protective systems, which may lead to cascading outages. The loss of synchronism of some generators may result from these outages or from operating conditions that violate a synchronous generator's field current limit, or in the case of variable speed wind turbine generator, the current limits of power switches. This paper investigates the impact of wind power plants on power system voltage stability by using synchrophasor measurements.

  7. Impacts of invasive plants on resident animals across ecosystems, taxa, and feeding types: a global assessment.

    Science.gov (United States)

    Schirmel, Jens; Bundschuh, Mirco; Entling, Martin H; Kowarik, Ingo; Buchholz, Sascha

    2016-02-01

    As drivers of global change, biological invasions have fundamental ecological consequences. However, it remains unclear how invasive plant effects on resident animals vary across ecosystems, animal classes, and functional groups. We performed a comprehensive meta-analysis covering 198 field and laboratory studies reporting a total of 3624 observations of invasive plant effects on animals. Invasive plants had reducing (56%) or neutral (44%) effects on animal abundance, diversity, fitness, and ecosystem function across different ecosystems, animal classes, and feeding types while we could not find any increasing effect. Most importantly, we found that invasive plants reduced overall animal abundance, diversity and fitness. However, this significant overall effect was contingent on ecosystems, taxa, and feeding types of animals. Decreasing effects of invasive plants were most evident in riparian ecosystems, possibly because frequent disturbance facilitates more intense plant invasions compared to other ecosystem types. In accordance with their immediate reliance on plants for food, invasive plant effects were strongest on herbivores. Regarding taxonomic groups, birds and insects were most strongly affected. In insects, this may be explained by their high frequency of herbivory, while birds demonstrate that invasive plant effects can also cascade up to secondary consumers. Since data on impacts of invasive plants are rather limited for many animal groups in most ecosystems, we argue for overcoming gaps in knowledge and for a more differentiated discussion on effects of invasive plant on native fauna. © 2015 John Wiley & Sons Ltd.

  8. Enhanced precipitation promotes decomposition and soil C stabilization in semiarid ecosystems, but seasonal timing of wetting matters

    Science.gov (United States)

    Campos, Xochi; Germino, Matthew; de Graaff, Marie-Anne

    2017-01-01

    AimsChanging precipitation regimes in semiarid ecosystems will affect the balance of soil carbon (C) input and release, but the net effect on soil C storage is unclear. We asked how changes in the amount and timing of precipitation affect litter decomposition, and soil C stabilization in semiarid ecosystems.MethodsThe study took place at a long-term (18 years) ecohydrology experiment located in Idaho. Precipitation treatments consisted of a doubling of annual precipitation (+200 mm) added either in the cold-dormant season or in the growing season. Experimental plots were planted with big sagebrush (Artemisia tridentata), or with crested wheatgrass (Agropyron cristatum). We quantified decomposition of sagebrush leaf litter, and we assessed organic soil C (SOC) in aggregates, and silt and clay fractions.ResultsWe found that: (1) increased precipitation applied in the growing season consistently enhanced decomposition rates relative to the ambient treatment, and (2) precipitation applied in the dormant season enhanced soil C stabilization.ConclusionsThese data indicate that prolonged increases in precipitation can promote soil C storage in semiarid ecosystems, but only if these increases happen at times of the year when conditions allow for precipitation to promote plant C inputs rates to soil.

  9. Field-Scale Partitioning of Ecosystem Respiration Components Suggests Carbon Stabilization in a Bioenergy Grass Ecosystem

    Science.gov (United States)

    Black, C. K.; Miller, J. N.; Masters, M. D.; Bernacchi, C.; DeLucia, E. H.

    2014-12-01

    Annually-harvested agroecosystems have the potential to be net carbon sinks only if their root systems allocate sufficient carbon belowground and if this carbon is then retained as stable soil organic matter. Soil respiration measurements are the most common approach to evaluate the stability of soil carbon at experimental time scales, but valid inferences require the partitioning of soil respiration into root-derived (current-year C) and heterotrophic (older C) components. This partitioning is challenging at the field scale because roots and soil are intricately mixed and physical separation in impossible without disturbing the fluxes to be measured. To partition soil flux and estimate the C sink potential of bioenergy crops, we used the carbon isotope difference between C3 and C4 plant species to quantify respiration from roots of three C4 grasses (maize, Miscanthus, and switchgrass) grown in a site with a mixed cropping history where respiration from the breakdown of old soil carbon has a mixed C3-C4 signature. We used a Keeling plot approach to partition fluxes both at the soil surface using soil chambers and from the whole field using continuous flow sampling of air within and above the canopy. Although soil respiration rates from perennial grasses were higher than those from maize, the isotopic signature of respired carbon indicated that the fraction of soil CO2 flux attributable to current-year vegetation was 1.5 (switchgrass) to 2 (Miscanthus) times greater in perennials than that from maize, indicating that soil CO2 flux came mostly from roots and turnover of soil organic matter was reduced in the perennial crops. This reduction in soil heterotrophic respiration, combined with the much greater quantities of C allocated belowground by perennial grasses compared to maize, suggests that perennial grasses grown as bioenergy crops may be able to provide an additional climate benefit by acting as carbon sinks in addition to reducing fossil fuel consumption.

  10. Oxidation stability of ice nuclei from plants

    Science.gov (United States)

    Felgitsch, Laura; Häusler, Thomas; Grothe, Hinrich

    2017-04-01

    Heterogeneous ice nucleation is an important process in cloud formation and therefore has direct influence on the radiation budget of the Earth. Biological ice nuclei (IN) are highly abundant in nature. Many plants have been found to produce IN. These IN are of special interest, since several have been found to be in a nano-particular/macromolecular size range (Pummer et al. 2015, Felgitsch et al. 2016). Particles of such a small size should show a high lifespan in the atmosphere. Further the substances can easily be attached to mineral dusts. Very little is known about the atmospheric fate of plant derived ice nuclei (IN) in case they become airborne. While they inherit the possibility to influence ice cloud formation, this property depends highly on the expected lifespan of the substance and of its ice nucleation activity in the atmosphere. For our experiment we exposed plant IN derived from black currant (berry juice) and birch (pollen washing water) to high concentrations of highly oxidative substances typically present in the atmosphere. The exposure lasted several hours and allowed us to monitor the changes in ice nucleation activity. Our results suggest a high stability towards oxidation leading to a high atmospheric life span of the ice nucleation activity if airborne. Pummer, B.G., Budke, C., Augustin-Bauditz, S., Niedermeier, D., Felgitsch, L., Kampf, C.J., Huber, R.G., Liedl, K.R., Loerting, T., Moschen, T., Schauperl, M., Tollinger, M., Morris, C.E., Wex, H., Grothe, H., Pöschl, U., Koop, T., and Fröhlich-Nowoisky, J.: Ice nucleation by water-soluble macromolecules, Atmos. Chem. Phys., 15, 4077-4091, 2015. Felgitsch , L., Bichler, M., Häusler, T., Hitzenberger, R., and Grothe, H.: Heterogeneous freezing of water triggered by berry juices from perenneal plants, submitted, 2016.

  11. 'Trophic whales' as biotic buffers: weak interactions stabilize ecosystems against nutrient enrichment.

    Science.gov (United States)

    Schwarzmüller, Florian; Eisenhauer, Nico; Brose, Ulrich

    2015-05-01

    Human activities may compromise biodiversity if external stressors such as nutrient enrichment endanger overall network stability by inducing unstable dynamics. However, some ecosystems maintain relatively high diversity levels despite experiencing continuing disturbances. This indicates that some intrinsic properties prevent unstable dynamics and resulting extinctions. Identifying these 'ecosystem buffers' is crucial for our understanding of the stability of ecosystems and an important tool for environmental and conservation biologists. In this vein, weak interactions have been suggested as stabilizing elements of complex systems, but their relevance has rarely been tested experimentally. Here, using network and allometric theory, we present a novel concept for a priori identification of species that buffer against externally induced instability of increased population oscillations via weak interactions. We tested our model in a microcosm experiment using a soil food-web motif. Our results show that large-bodied species feeding at the food web's base, so called 'trophic whales', can buffer ecosystems against unstable dynamics induced by nutrient enrichment. Similar to the functionality of chemical or mechanical buffers, they serve as 'biotic buffers' that take up stressor effects and thus protect fragile systems from instability. We discuss trophic whales as common functional building blocks across ecosystems. Considering increasing stressor effects under anthropogenic global change, conservation of these network-intrinsic biotic buffers may help maintain the stability and diversity of natural ecosystems.

  12. Ecosystem stability and the distribution of community matrix eigenvalues

    Energy Technology Data Exchange (ETDEWEB)

    Harte, J.

    1977-07-01

    A definition or measure of ecological stability is introduced which is advantageous in that it may be empirically accessible and in that it relates to practical concerns in situations of environmental stress. It is shown how this measure can be analyzed, for an arbitrary system described by a community matrix, by model-independent mathematical methods. The relationship between the stability of any such system and both the distribution of community matrix eigenvalues and the pattern of pathway linkages is discussed.

  13. Resilience and stability of a pelagic marine ecosystem

    DEFF Research Database (Denmark)

    Lindegren, Martin; Checkley, David M.; Ohman, Mark D.;

    2016-01-01

    reached regarding the positive BEF relationship, a number of important challenges remain unanswered. These primarily concern the underlying mechanisms by which diversity increases resilience and community stability, particularly the relative importance of statistical averaging and functional....... Furthermore, we show strong temporal asynchrony between key species or functional groups within multiple trophic levels caused by opposite responses to these drivers. We argue that functional complementarity is the primary mechanism reducing community variability and promoting resilience and stability...

  14. Species-diversified plant cover enhances orchard ecosystem resistance to climatic stress and soil erosion in subtropical hillsid

    Institute of Scientific and Technical Information of China (English)

    陈欣; 杨一松; 唐建军

    2004-01-01

    Naturally occurring plants in agroecosystem evidently play an important role in ecosystem stability. Field studies on the ecological effects of native plants conserved in orchard and their resistance to adverse climatic stress, and soil erosion were conducted from 1998 to 2001 in a newly developed Changshan-huyou (Citrus changshan-huyou Y.B. Chang) orchard. The experimental area covered 150 ha in typical red soil hilly region in southeastern China. The experimental design was a randomized complete block with six combinations of twelve plant species with four replications. All species used were native in the orchard. Plots were 15×8m2 and separated by 2m buffer strips. Precipitation, soil erosion in rainstorm days and aboveground biomass of plant community when rainstorm days ended, soil temperature and moisture under various plant covers during seasonal megathermal drought period, antiscourability of soil with different root density under various simulated rainfalls were measured. Plant cover significantly decreased the daily highest and mean soil temperature and its daily variation in hot-drought season, but there was no significant difference of the alleviation among various plant covers. Plant covers significantly increased the soil moisture in seasonal megathermal drought period. Better moisture maintenance and soil erosion reduction was found when the plant species numbers in cover plant communities increased from one to eight. Higher root density in plant communities with higher species richness increased significantly the antiscourability of the soil. It was suggested that conserving plant communities with diversified native species could produce the best positive ecological effects on citrus orchard ecosystem stability.

  15. Species-diversified plant cover enhances orchard ecosystem resistance to climatic stress and soil erosion in subtropical hillside

    Institute of Scientific and Technical Information of China (English)

    陈欣; 杨一松; 唐建军

    2004-01-01

    Naturally occurring plants in agroecosystem evidently play an important role in ecosystem stability. Field studies on the ecological effects of native plants conserved in orchard and their resistance to adverse climatic stress, and soil erosion were conducted from 1998 to 2001 in a newly developed Changshan-huyou (Citrus changshan-huyou Y.B. Chang)orchard. The experimental area covered 150 ha in typical red soil hilly region in southeastern China. The experimental design was a randomized complete block with six combinations of twelve plant species with four replications. All species used were native in the orchard. Plots were 15×8m2 and separated by 2 m buffer strips. Precipitation, soil erosion in rainstorm days and aboveground biomass of plant community when rainstorm days ended, soil temperature and moisture under various plant covers during seasonal megathermal drought period, antiscourability of soil with different root density under various simulated rainfalls were measured. Plant cover significantly decreased the daily highest and mean soil temperature and its daily variation in hot-drought season, but there was no significant difference of the alleviation among various plant covers. Plant covers significantly increased the soil moisture in seasonal megathermal drought period. Better moisture maintenance and soil erosion reduction was found when the plant species numbers in cover plant communities increased from one to eight. Higher root density in plant communities with higher species richness increased significantly the antiscourability of the soil. It was suggested that conserving plant communities with diversified native species could produce the best positiveecological effects on citrus orchard ecosystem stability.

  16. Nitrogen Uptake Preferences by Plants in Arid and Semiarid Ecosystems

    Science.gov (United States)

    Macko, S.; Wang, L.; D'Odorico, P.

    2005-12-01

    In arid and semiarid ecosystems like African savannas, nutrient availability varies spatially and temporally and nutrients are considered to be a major limiting factor for growth in addition to water availability. Preference for different nitrogen forms presumably enhances the survivorship and fitness of plants since the relative abundances of nitrate and ammonium varies between drier and wetter areas. To test the hypothesis that species developing in dry areas will prefer nitrate whereas species growing in wet areas will prefer ammonium, a controlled experiment using a greenhouse was undertaken. Six native African grass species from different precipitation regimes were used in this study. Two species were from relatively wet areas (Pandamatenga, Botswana, precipitation = 698 mm/year), two were from relatively dry areas (Tshane, Botswana, precipitation = 232 mm/year) and other two were from intermediate environments (Ghanzi, Botswana, precipitation = 400 mm/year). The grass seeds were collected in the field during the dry season of 2004 and using germination pans, were grown in a greenhouse. When individuals were mature, they were transferred into plastic pots (one individual per pot) containing commercial sand. After one week period of adjustment, a 15N labeled fertilizer (NH4NO3) was applied. The total N applied as fertilizer was comparable to the mineralized field N based on a calculated rate for the top 15 cm of soil. A pair of individual plants was treated as an experimental unit. Each plant received the same amount of total N fertilizer, but one was 15NO3 labeled and another was 15NH4 labeled. Nutrient uptake preference was determined by the 15N difference between pairs. The preliminary results with three species shows that, the individuals from dry area ( Enneapogon cenchroides from Tshane) has significantly higher foliar 15N signatures in the 15NO3 labeling treatment (p = 0.0103) and no difference in root 15N signatures. Whereas individuals from the wet

  17. A large-scale forest fragmentation experiment: the Stability of Altered Forest Ecosystems Project

    OpenAIRE

    Ewers, Robert M.; Didham, Raphael K.; Fahrig, Lenore; Ferraz, Gonçalo; Hector, Andy; Holt, Robert D; Kapos, Valerie; Reynolds, Glen; Sinun, Waidi; Snaddon, Jake L.; Turner, Edgar C.

    2011-01-01

    Opportunities to conduct large-scale field experiments are rare, but provide a unique opportunity to reveal the complex processes that operate within natural ecosystems. Here, we review the design of existing, large-scale forest fragmentation experiments. Based on this review, we develop a design for the Stability of Altered Forest Ecosystems (SAFE) Project, a new forest fragmentation experiment to be located in the lowland tropical forests of Borneo (Sabah, Malaysia). The SAFE Project repres...

  18. PIONEER PLANTS FOR ECOSYSTEM RECOVERY IN DRAINAGE BASIN OF ERLONGSHAN RESERVOIR IN HEILONGJIANG PROVINCE, CHINA

    Institute of Scientific and Technical Information of China (English)

    ZHANG Xue-ping; ZHANG Yi; CAO Hui-cong

    2004-01-01

    This article reveals the ecological features and the theories and methods of introducing pioneer plants in the process of eco-restoring in different degenerative ecosystems in the drainage basin of Erlongshan Reservoir in Heilongjiang Province by systemically studying the deteriorative ecosystems and using recovery theory. The study shows that with the rise in degenerative degrees of the ecosystems, bio-species and bio-diversity sharply decrease in the study area and microclimate becomes warmer and drier in natural ecosystem. Therefore, we must attach importance to the construction of plants and biodiversity. In the study, different pioneer plants are selected for different degenerative ecosystems to restore and maintain the service functions of the ecosystems.

  19. Plutonium in a grassland ecosystem. [Rocky Flats Plant

    Energy Technology Data Exchange (ETDEWEB)

    Little, C.A.

    1976-08-01

    A study was made of plutonium contamination of grassland at the Rocky Flats plant northwest of Denver, Colorado. Of interest were: the definition of major plutonium-containing ecosystem compartments; the relative amounts in those compartments; how those values related to studies done in other geographical areas; whether or not the predominant isotopes, /sup 238/Pu and /sup 239/Pu, behaved differently; and what mechanisms might have allowed for the observed patterns of contamination. Samples of soil, litter, vegetation, arthropods, and small mammals were collected for Pu analysis and mass determination from each of two macroplots. Small aliquots (5 g or less) were analyzed by a rapid liquid scintillation technique and by alpha spectrometry. Of the compartments sampled, greater than 99 percent of the total plutonium was contained in the soil and the concentrations were significantly inversely correlated with distance from the contamination source, depth of the sample, and particle size of the sieved soil samples. The soil data suggested that the distribution of contamination largely resulted from physical transport processes.

  20. Modeling the effects of organic nitrogen uptake by plants on the carbon cycling of boreal ecosystems

    Directory of Open Access Journals (Sweden)

    Q. Zhu

    2013-08-01

    Full Text Available Boreal forest and tundra are the major ecosystems in the northern high latitudes in which a large amount of carbon is stored. These ecosystems are nitrogen-limited due to slow mineralization rate of the soil organic nitrogen. Recently, abundant field studies have found that organic nitrogen is another important nitrogen supply for boreal ecosystems. In this study, we incorporated a mechanism that allowed boreal plants to uptake small molecular amino acids into a process-based biogeochemical model, the Terrestrial Ecosystem Model (TEM, to evaluate the impact of organic nitrogen uptake on ecosystem carbon cycling. The new version of the model was evaluated at both boreal forest and tundra sites. We found that the modeled organic nitrogen uptake accounted for 36–87% of total nitrogen uptake by plants in tundra ecosystems and 26–50% for boreal forests, suggesting that tundra ecosystem might have more relied on the organic form of nitrogen than boreal forests. The simulated monthly gross ecosystem production (GPP and net ecosystem production (NEP tended to be larger with the new version of the model since the plant uptake of organic nitrogen alleviated the soil nitrogen limitation especially during the growing season. The sensitivity study indicated that the most important factors controlling the plant uptake of organic nitrogen were the maximum root uptake rate (Imax and the radius of the root (r0 in our model. The model uncertainty due to uncertain parameters associated with organic nitrogen uptake at tundra ecosystem was larger than at boreal forest ecosystems. This study suggests that considering the organic nitrogen uptake by plants is important to boreal ecosystem carbon modeling.

  1. The Stability of Revegetated Ecosystems in Sandy Areas: An Assessment and Prediction Index

    Directory of Open Access Journals (Sweden)

    Lei Huang

    2015-04-01

    Full Text Available The stability and sustainability of revegetated ecosystems is a central topic in ecological research. In this study, long-term monitoring and focused research on vegetation, soil and soil moisture from 2006 to 2012 were used to develop a model for evaluating indices of ecosystem stability using the analytical hierarchy process method. The results demonstrated that rainfall (R, vegetation coverage (C, and surface soil moisture (S were the three most influential factors among the 14 indicators considered in a revegetated desert area in the Tengger Desert, China. A stability index (SI was defined as SI = VAR (R × VAR (C/VAR (S, and a comparative study was conducted to examine the stability index of the natural vegetation community. The SI was divided into three regimes: SI < 0.006 was stable, 0.006 ≤ SI < 0.015 was semi-stable, and 0.015 ≤ SI was unstable. The stable, semi-stable and unstable periods of revegetated ecosystems in our simulations were 191, 17 and 11 years, respectively, within the total modeling period of 219 years. These results indicated that the revegetated desert ecosystem would be stable in most years during the vegetation succession, and this study presents new ideas for future artificial vegetation management in arid desert regions.

  2. General stabilizing effects of plant diversity on grassland productivity through population asynchrony and overyielding.

    Science.gov (United States)

    Hector, A; Hautier, Y; Saner, P; Wacker, L; Bagchi, R; Joshi, J; Scherer-Lorenzen, M; Spehn, E M; Bazeley-White, E; Weilenmann, M; Caldeira, M C; Dimitrakopoulos, P G; Finn, J A; Huss-Danell, K; Jumpponen, A; Mulder, C P H; Palmborg, C; Pereira, J S; Siamantziouras, A S D; Terry, A C; Troumbis, A Y; Schmid, B; Loreau, M

    2010-08-01

    Insurance effects of biodiversity can stabilize the functioning of multispecies ecosystems against environmental variability when differential species' responses lead to asynchronous population dynamics. When responses are not perfectly positively correlated, declines in some populations are compensated by increases in others, smoothing variability in ecosystem productivity. This variance reduction effect of biodiversity is analogous to the risk-spreading benefits of diverse investment portfolios in financial markets. We use data from the BIODEPTH network of grassland biodiversity experiments to perform a general test for stabilizing effects of plant diversity on the temporal variability of individual species, functional groups, and aggregate communities. We tested three potential mechanisms: reduction of temporal variability through population asynchrony; enhancement of long-term average performance through positive selection effects; and increases in the temporal mean due to overyielding. Our results support a stabilizing effect of diversity on the temporal variability of grassland aboveground annual net primary production through two mechanisms. Two-species communities with greater population asynchrony were more stable in their average production over time due to compensatory fluctuations. Overyielding also stabilized productivity by increasing levels of average biomass production relative to temporal variability. However, there was no evidence for a performance-enhancing effect on the temporal mean through positive selection effects. In combination with previous work, our results suggest that stabilizing effects of diversity on community productivity through population asynchrony and overyielding appear to be general in grassland ecosystems.

  3. Ecosystem development in roadside grasslands: biotic control, plant-soil interactions, and dispersal limitations

    OpenAIRE

    García-Palacios, Pablo; Bowker, Matthew A.; Maestre, Fernando T.; Soliveres, Santiago; Valladares, Fernando; Papadopoulos, Jorge; Escudero, Adrián

    2011-01-01

    Roadside grasslands undergoing secondary succession are abundant, and represent ecologically meaningful examples of novel, human-created ecosystems. Interactions between plant and soil communities (hereafter plant–soil interactions) are of major importance in understanding the role of biotic control in ecosystem functioning, but little is known about these links in the context of ecosystem restoration and succession. The assessment of the key biotic communities and interactions driving ecosys...

  4. Assessing and monitoring impacts of genetically modified plants on agro-ecosystems

    DEFF Research Database (Denmark)

    Arpaia, S.; Messéan, A.; Birch, N.A.;

    2014-01-01

    -funded research project AMIGA − Assessing and monitoring Impacts of Genetically modified plants on Agro-ecosystems − aims to address this issue, by providing a framework that establishes protection goals and baselines for European agro-ecosystems, improves knowledge on the potential long term environmental...... focuses on ecological studies in different EU regions, the sustainability of GM crops is estimated by analysing the functional components of the agro-ecosystems and specific experimental protocols are being developed for this scope....

  5. Positive Plant Diversity-Soil Stability Relationships are Mediated through Roots in the Songnen Grassland: Chronosequence Evidence

    Directory of Open Access Journals (Sweden)

    Liang-Jun HU

    2013-12-01

    Full Text Available Living plant diversity (excluding the litter issue may affect below-ground properties and processes, which is critical to obtaining an integrated biodiversity-ecosystem functioning theory. However, related patterns and underlying mechanisms have rarely been examined, especially lacking long-term evidence. We conducted a factorial crossed sample survey to examine the effects of plant diversity on soil stability over succession based on space-for-time substitution in the Songnen Steppes, North-Eastern China. The results indicate that, under natural colonizing conditions, species-poor systems achieved lower soil stability than species-rich systems, regardless of successional stage. However, soil stability was significantly regulated by plant species richness (number, composition (identity, density (abundance, and functional roles. Our results confirm that a long-term positive plant diversity-soil stability relationship exists in steppe succession. In particular, this enhanced effect of biodiversity on soil stability may operate via diversifying plant root traits. Our results may underpin an integrated biodiversity-ecosystem functioning theory, and improve human use and conservation management of natural resources at an integrated ecosystem level.

  6. Do plant-based amendments improve soil physiochemical and microbiological properties and plant growth in dryland ecosystems?

    Science.gov (United States)

    Kneller, Tayla; Harris, Richard; Muñoz-Rojas, Miriam

    2017-04-01

    Background Land intensive practices including mining have contributed to the degradation of landscapes globally. Current challenges in post-mine restoration revolve around the use of substrates poor in organic materials (e.g. overburden and waste rock) and lack of original topsoil which may result in poor seedling recruitment and in later stages in soil nutrient deficiency, metal toxicity, decreased microbial activity and high salinity (Bateman et al., 2016; Muñoz-Rojas et al., 2016). Despite continuous efforts and advances we have not proportionally advanced our capability to successfully restore these landscapes following mining. Recent attempts to improve plant establishment in arid zone restoration programs have included the application of plant based amendments to soil profiles. This approach usually aims to accelerate soil reconstruction via improvement of soil aggregate stability and increase of soil organic carbon, and water holding capacity. Whilst a significant amount of recent research has focused on the application of such amendments, studies on the potential application of plant based materials to recover soil functionality and re-establish plant communities in post-mined landscapes in arid regions are limited. Here we will discuss our work investigating the application of a plant based amendment on soil substrates commonly used in post mining restoration in the Pilbara region, Western Australia. Methodology The study was conducted in a glasshouse facility where environmental conditions were continuously monitored. Using two growth materials (topsoil and waste rock) and a plant based amendment (dry biomass of the most common grass in the Pilbara, Triodia wiseana) five different treatments were tested. Treatments consisted of control soil treatments (topsoil, waste and a mixture of the former soil types (mixture)) and two amended soil treatments (waste amended and mixture amended). Additionally, three different vegetation communities were studies

  7. Long-term exposure to elevated CO2 enhances plant community stability by suppressing dominant plant species in a mixed-grass prairie.

    Science.gov (United States)

    Zelikova, Tamara Jane; Blumenthal, Dana M; Williams, David G; Souza, Lara; LeCain, Daniel R; Morgan, Jack; Pendall, Elise

    2014-10-28

    Climate controls vegetation distribution across the globe, and some vegetation types are more vulnerable to climate change, whereas others are more resistant. Because resistance and resilience can influence ecosystem stability and determine how communities and ecosystems respond to climate change, we need to evaluate the potential for resistance as we predict future ecosystem function. In a mixed-grass prairie in the northern Great Plains, we used a large field experiment to test the effects of elevated CO2, warming, and summer irrigation on plant community structure and productivity, linking changes in both to stability in plant community composition and biomass production. We show that the independent effects of CO2 and warming on community composition and productivity depend on interannual variation in precipitation and that the effects of elevated CO2 are not limited to water saving because they differ from those of irrigation. We also show that production in this mixed-grass prairie ecosystem is not only relatively resistant to interannual variation in precipitation, but also rendered more stable under elevated CO2 conditions. This increase in production stability is the result of altered community dominance patterns: Community evenness increases as dominant species decrease in biomass under elevated CO2. In many grasslands that serve as rangelands, the economic value of the ecosystem is largely dependent on plant community composition and the relative abundance of key forage species. Thus, our results have implications for how we manage native grasslands in the face of changing climate.

  8. Plant diversity effects on ecosystem evapotranspiration and carbon uptake: a controlled environment (Ecotron) and modeling approach

    Science.gov (United States)

    Milcu, Alexandru; Roy, Jacques

    2016-04-01

    Effects of species and functional diversity of plants on ecosystem evapotranspiration and carbon fluxes have been rarely assessed simultaneously. Here we present the results from an experiment that combined a lysimeter setup in a controlled environment facility (Ecotron) with large ecosystem samples/ monoliths originating from a long-term biodiversity experiment ("The Jena Experiment") and a modelling approach. We aimed at (1) quantifying the impact of plant species richness (4 vs. 16 species) on day- and night-time ecosystem water vapor fluxes and carbon uptake, (2) partitioning ecosystem evapotranspiration into evaporation and plant transpiration using the Shuttleworth and Wallace (SW) energy partitioning model, and (3) identifying the most parsimonious predictors of water vapor vapor and CO2 fluxes using plant functional trait-based metrics such as functional diversity and community weighted means. The SW model indicated that at low plant species richness, a higher proportion of the available energy was diverted to evaporation (a non-productive flux), while at higher species richness the proportion of ecosystem transpiration (a production-related water flux) increased. This led to an increased carbon gain per amount of water vapor loss (i.e. increased water use efficiency). While the LAI controlled the carbon and water fluxes, we also found that the diversity of plant functional traits, and in particular of leaf nitrogen concentration are potential important predictors of ecosystem transpiration and carbon uptake and consequently significantly contributed to increase in water use efficiency in communities with higher plant diversity.

  9. Twelve invasive plant taxa in U.S. western riparian ecosystems

    Science.gov (United States)

    Assessments of stream ecosystems often include an evaluation of riparian condition; a key stressor in riparian ecosystems is the presence of invasive plants. We analyzed the distribution of 12 invasive taxa (common burdock [Arctium minus], giant reed [Arundo donax], cheatgrass [B...

  10. Exotic plant traits lead to functional diversity decline in novel ecosystems

    Science.gov (United States)

    Exotic species have become common and even dominant in some grasslands forming novel ecosystems because the species in them have no common evolutionary history. Recent work on these novel ecosystems suggest that exotic species contribute to diversity declines. In order to identify the plant traits...

  11. Economic valuation of plant diversity storage service provided by Brazilian rupestrian grassland ecosystems.

    Science.gov (United States)

    Resende, F M; Fernandes, G W; Coelho, M S

    2013-11-01

    The rupestrian grassland ecosystems provide various goods and services to society and support a significant amount of biological diversity. Notably the rich plant diversity has high levels of endemism and a variety of uses among the local communities and general society. Despite the socio-ecological importance of these ecosystems, they are subjected to significant anthropogenic pressures. The goal of this study is to perform economic valuation of the plant diversity storage service provided by rupestrian grassland ecosystems to provide grounds for the development of conservation policies and encourage sustainable practices in these ecosystems. Given the intense human disturbances and unique flora, the Serra do Cipó (southern portion of the Espinhaço Range in southeast Brazil) was selected for the study. We estimate the monetary value related to the plant diversity storage service provided by the study area using the maintenance costs of native plants in the living collections of the botanical garden managed by the Zoobotanical Foundation - Belo Horizonte (located 97 km from Serra do Cipó). The plant diversity storage value provided by Serra do Cipó ecosystems is significant, reaching US$25.26 million year-1. This study contributes to the development of perspectives related to the conservation of rupestrian grassland ecosystems as well as others threatened tropical ecosystems with high biodiversity.

  12. Photosynthetic properties of boreal bog plant species and their contribution to ecosystem level carbon sink

    Science.gov (United States)

    Korrensalo, Aino; Hájek, Tomas; Alekseychik, Pavel; Rinne, Janne; Vesala, Timo; Mehtätalo, Lauri; Mammarella, Ivan; Tuittila, Eeva-Stiina

    2016-04-01

    Boreal bogs have a low number of plant species, but a large diversity of growth forms. This heterogeneity might explain the seasonally less varying photosynthetic productivity of these ecosystems compared to peatlands with vegetation consisting of fewer growth forms. The differences in photosynthetic properties within bog species and phases of growing season has not been comprehensively studied. Also the role of different plant species for the ecosystem level carbon (C) sink function is insufficiently known. We quantified the seasonal variation of photosynthetic properties in bog plant species and assessed how this variation accounts for the temporal variation in the ecosystem C sink. Photosynthetic light response of 11 vascular plant and 8 Sphagnum moss species was measured monthly over the growing season of 2013. Based on the species' light response parameters, leaf area development and areal coverage, we estimated the ecosystem level gross photosynthesis rate (PG) over the growing season. The level of upscaled PG was verified by comparing it to the ecosystem gross primary production (GPP) estimate calculated based on eddy covariance (EC) measurements. Although photosynthetic parameters differed within plant species and months, these differences were of less importance than expected for the variation in ecosystem level C sink. The most productive plant species at the ecosystem scale were not those with the highest maximum potential photosynthesis per unit of leaf area (Pmax), but those having the largest areal coverage. Sphagnum mosses had 35% smaller Pmax than vascular plants, but had higher photosynthesis at the ecosystem scale throughout the growing season. The contribution of the bog plant species to the ecosystem level PG differed over the growing season. The seasonal variation in ecosystem C sink was mainly controlled by phenology. Sedge PG had a sharp mid-summer peak, but the PG of evergreen shrubs and Sphagna remained rather stable over the growing season

  13. Considerations on a data-driven approach to identify plant's imprint on ecosystem functioning

    Science.gov (United States)

    Musavi, Talie; Kattge, Jens; Mahecha, Miguel; Reichstein, Markus; Van de Weg, Martine Janet; Van Bodegom, Peter; Bahn, Michael; Migliavacca, Mirco; Wirth, Christian; Reich, Peter

    2015-04-01

    Terrestrial ecosystems strongly determine the exchange of carbon, water and energy between the biosphere and atmosphere. These exchanges are influenced and partly driven by environmental conditions (e.g. local meteorology, soils), but generally mediated by organisms. In commonly used terrestrial biosphere models, this principle is implemented by process-based descriptions of plant functioning at the organ level. In order to validate these model formulations, we need an independent empirical approach to understand the plant's imprint on ecosystem functioning. We use land-atmosphere exchange of fluxes of CO2, H2O and energy in tandem with environmental controls available in FLUXNET to quantify "ecosystem functional properties" (EFPs). The latter are generally time-invariant ecosystem specific properties, for instance process sensitivities or efficiencies that shape ecosystem scale responses. Our crucial question is if plant traits measured at the organ level (available e.g. in the TRY database) can elucidate the characteristics of EFPs. In this study we follow this new avenue and link the two global databases FLUXNET and TRY to study the role of plants for biogeochemical cycles across a large number of different globally distributed ecosystem types. We aim to address emerging difficulties and possible solutions. For instance, we show that using average values of plant traits from TRY that are not necessarily measured at the fluxnet sites is of use but has clear limitations. However having information on the amount of vegetation at the sites derived from remote sensing is needed for weighting the plant traits. In addition, we have to consider that EFPs are not really time-invariant and subject to alterations after disturbance, meteorological extremes, management etc. Overall, we provide an outlook on perspectives and applications of empirical analyses of plants' imprint on ecosystem functioning by combining remote sensing, in situ measured plant traits and ecosystem

  14. Role of terrestrial ecosystems in determining CO{sub 2} stabilization and recovery behaviour

    Energy Technology Data Exchange (ETDEWEB)

    Jones, Chris; Liddicoat, Spencer (Met Office Hadley Centre, Exeter (United Kingdom)); Lowe, Jason (Met Office Hadley Centre, Dept. of Meteorology, Univ. of Reading, Reading (United Kingdom))

    2010-11-15

    Terrestrial ecosystems are sensitive to climate and can also influence it through both biophysical and biogeochemical feedbacks. Natural carbon uptake by ecosystems will control future evolution of CO{sub 2} and climate, but the ecosystems themselves may be committed to long-term changes. Here we use a coupled climate-carbon cycle GCM with dynamic vegetation to investigate the policy-relevance of these feedbacks in several idealized scenarios. Our results show that the natural carbon cycle in the ocean and on land controls the recovery of atmospheric CO{sub 2} following emissions reductions at three action points during the 21st century. Initial rates of recovery are similar but for different reasons. Ocean carbon uptake exceeds terrestrial uptake, with higher CO{sub 2} levels leading to increased ocean uptake whereas on land greater climate change at higher CO{sub 2} leads to decreased carbon storage. There are long-term committed changes to terrestrial ecosystems which vary in sign regionally and create a complex dynamic response of terrestrial carbon storage as it slowly approaches a new steady state. Neither stabilization nor CO{sub 2} recovery allows ecosystems to recover back to their initial state and the ecosystems continue to respond for decades or even centuries following emissions reductions. These long-term committed changes, in addition to realized, transient changes, must be considered when defining dangerous climate change and identifying emission-pathways to avoid it.

  15. Fractionation of Nitrogen Isotopes by Plants with Different Types of Mycorrhiza in Mountain Tundra Ecosystems

    Science.gov (United States)

    Buzin, Igor; Makarov, Mikhail; Maslov, Mikhail; Tiunov, Alexei

    2017-04-01

    We studied nitrogen concentration and nitrogen isotope composition in plants from four mountain tundra ecosystems in the Khibiny Mountains. The ecosystems consisted of a toposequence beginning with the shrub-lichen heath (SLH) on the ridge and upper slope, followed by the Betula nana dominated shrub heath (SH) on the middle slope, the cereal meadow (CM) on the lower slope and the sedge meadow (SM) at the bottom of the slope. The inorganic nitrogen concentration of the soils from the studied ecosystems were significantly different; the SLH soil was found to contain the minimum concentration of N-NH4+ and N-NO3- , while in the soils of the meadow ecosystems these concentrations were much higher. The concentration of nitrogen in leaves of the dominant plant species in all of the ecosystems is directly connected with the concentration of inorganic nitrogen in the soils, regardless of the plant's mycorrhizal symbiosis type. However, such a correlation is not apparent in the case of plant roots, especially for plant roots with ectomycorrhiza and ericoid mycorrhiza. The majority of plant species with these types of mycorrhiza in the SH and particularly in the CM were enriched in 15N in comparison with the SLH (such plants were not found within the SM). This could be due to several reasons: 1) the decreasing role of mycorrhiza in nitrogen consumption and therefore in the fractionation of isotopes in the relatively-N-enriched ecosystems; 2) the use of relatively-15N-enriched forms of nitrogen for plant nutrition in meadow ecosystems. This heavier nitrogen isotope composition in plant roots with ectomycorrhiza and ericoid mycorrhiza in ecosystems with available nitrogen enriched soils doesn't correspond to the classical idea of mycorrhiza decreasing participation in nitrogen plant nutrition. The analysis of the isotope composition of separate labile forms of nitrogen makes it possible to explain the phenomenon. Not all arbuscular mycorrhizal species within the sedge meadow

  16. Modeling Hawaiian ecosystem degradation due to invasive plants under current and future climates

    Science.gov (United States)

    Vorsino, Adam E.; Fortini, Lucas B.; Amidon, Fred A.; Miller, Stephen E.; Jacobi, James D.; Price, Jonathan P.; `Ohukani`ohi`a Gon, Sam; Koob, Gregory A.

    2014-01-01

    Occupation of native ecosystems by invasive plant species alters their structure and/or function. In Hawaii, a subset of introduced plants is regarded as extremely harmful due to competitive ability, ecosystem modification, and biogeochemical habitat degradation. By controlling this subset of highly invasive ecosystem modifiers, conservation managers could significantly reduce native ecosystem degradation. To assess the invasibility of vulnerable native ecosystems, we selected a proxy subset of these invasive plants and developed robust ensemble species distribution models to define their respective potential distributions. The combinations of all species models using both binary and continuous habitat suitability projections resulted in estimates of species richness and diversity that were subsequently used to define an invasibility metric. The invasibility metric was defined from species distribution models with 0.8; True Skill Statistic >0.75) as evaluated per species. Invasibility was further projected onto a 2100 Hawaii regional climate change scenario to assess the change in potential habitat degradation. The distribution defined by the invasibility metric delineates areas of known and potential invasibility under current climate conditions and, when projected into the future, estimates potential reductions in native ecosystem extent due to climate-driven invasive incursion. We have provided the code used to develop these metrics to facilitate their wider use (Code S1). This work will help determine the vulnerability of native-dominated ecosystems to the combined threats of climate change and invasive species, and thus help prioritize ecosystem and species management actions.

  17. Modeling Hawaiian ecosystem degradation due to invasive plants under current and future climates.

    Directory of Open Access Journals (Sweden)

    Adam E Vorsino

    Full Text Available Occupation of native ecosystems by invasive plant species alters their structure and/or function. In Hawaii, a subset of introduced plants is regarded as extremely harmful due to competitive ability, ecosystem modification, and biogeochemical habitat degradation. By controlling this subset of highly invasive ecosystem modifiers, conservation managers could significantly reduce native ecosystem degradation. To assess the invasibility of vulnerable native ecosystems, we selected a proxy subset of these invasive plants and developed robust ensemble species distribution models to define their respective potential distributions. The combinations of all species models using both binary and continuous habitat suitability projections resulted in estimates of species richness and diversity that were subsequently used to define an invasibility metric. The invasibility metric was defined from species distribution models with 0.8; True Skill Statistic >0.75 as evaluated per species. Invasibility was further projected onto a 2100 Hawaii regional climate change scenario to assess the change in potential habitat degradation. The distribution defined by the invasibility metric delineates areas of known and potential invasibility under current climate conditions and, when projected into the future, estimates potential reductions in native ecosystem extent due to climate-driven invasive incursion. We have provided the code used to develop these metrics to facilitate their wider use (Code S1. This work will help determine the vulnerability of native-dominated ecosystems to the combined threats of climate change and invasive species, and thus help prioritize ecosystem and species management actions.

  18. The Transfer and diffusion of Cesium 137 within forest ecosystem in Fukushima after the nuclear power plant accident

    Energy Technology Data Exchange (ETDEWEB)

    Suzuki, Takahiro; Murakami, Masashi [Community Ecology Lab., Biology Course, Faculty of Science, Chiba University, Chiba, 263-8522 (Japan); Ishii, Nobuyoshi [National Institute of Radiological Sciences, Chiba, 263-8555 (Japan); Tanoi, Keitaro; Hirose, Atsushi; Ohte, Nobuhito [Graduate School of Agricultural and Life Sciences, The University of Tokyo, Tokyo, 113-8657 (Japan)

    2014-07-01

    A large amount of radionuclides was released from the Fukushima Daiichi Nuclear Power Plant (FDNPP) accident after the disastrous earthquake and subsequent tsunami of March 2011. Among the variety of radionuclides released from FDNPP, cesium 137 ({sup 137}Cs) is the most worrying radionuclide in the environment, with a half-life of 30 years. Since most of the Japanese land area is covered by forest, the distribution and transportation of radioactive materials within forest ecosystems should be conscientiously monitored. In Europe, many studies reported that the {sup 137}Cs deposition caused by the Chernobyl accident has still been distributed in the litter and soil layers and has become a source for the soil-to-plant transfer. Most of these studies emphasize the 'stability' of {sup 137}Cs within forest ecosystems, because {sup 137}Cs are considered to be strongly and immediately fixed in clay minerals. Even though there are many studies of the soil-to-plant transfer of {sup 137}Cs in forest after several years of Chernobyl accident, very initial distribution and transfer of {sup 137}Cs in food web within one to two years after the deposition in forest ecosystems have never been examined. The evaluation of the initial dynamics of {sup 137}Cs in forest ecosystems should be quite important because of the increasing stability of {sup 137}Cs after the deposition. The accumulation and transfer of {sup 137}Cs through food web within forest ecosystems were examined by collecting various organisms at forests in Fukushima. The {sup 137}Cs concentrations, natural Cs and K concentrations, and delta {sup 15}N of the specimens were measured to evaluate the occurrence of bioaccumulation or bio-diffusion of {sup 137}Cs through tropic interaction within forest ecosystem. {sup 137}Cs was highly concentrated on leaf litters which had been deposited in autumn 2010, before the accident. This accumulated {sup 137}Cs had transferred to higher trophic organisms mainly through

  19. Pasture degradation in Tibet: Drivers, mechanisms and consequences for C stocks and ecosystem stability

    Science.gov (United States)

    Kuzyakov, Yakov; Schleuss, Per-Marten; Guggenberger, Georg; Miehe, Georg; Coners, Heinz; Foken, Thomas; Wesche, Karsten; Hafner, Silke; Biermann, Tobias; Babel, Wolfgang; Gerken, Tobias; Unteregelsbacher, Sebastian; Seeber, Elke; Spielvogel, Sandra; Ingrisch, Johannes; Li, Xiaogang; Yue, Sun; Li, Qianru; Xu, Xingliang

    2017-04-01

    Kobresia grasslands on Tibetan Plateau have accumulated tremendous organic carbon (C) stocks, are an important grazing ground for local herdsmen, host a major portion of the regional terrestrial biodiversity, and supply large areas of SE Asia with water. All these ecosystem functions are threatened by large-scale soil degradation on the Tibetan Plateau. Nonetheless, the patterns and mechanisms of Kobresia pasture degradation, visible across the entire Tibetan Plateau, remain unknown. In the K. pygmaea core area, we studied natural and anthropogenic drivers of pasture degradation to discover new mechanisms and associated processes of soil organic carbon (SOC) loss. We show that livestock overgrazing and trampling in recent decades have triggered grassland degradation by initiating plant death and reducing grassland recovery. Combined with the harsh climate, this destroys the protective Kobresia turf. Considering these processes as well as other anthropogenic and natural drivers, a novel pasture degradation concept was developed. Pasture soils corresponding to the fiwe degradation stages were sampled and analyzed for physical, chemical and biological properties. Soil drought and frost lead to polygonal cracking of the Kobresia turf, already weakened by overgrazing. This induces gradual erosion by wind and water, extends the cracks and removes the upper carbon-enriched soil. Erosion-derived SOC losses amount to 5 kg C m-2 and are aggravated by decreasing root C input and increased SOC mineralization (both ca. 2.5 kg C m-2). Mineralization-derived SOC loss was reflected by a negative δ13C shift of SOC going from intact to severely degraded stages, and was caused by a relative enrichment of 13C-depleted lignin. In sum, degradation has released tremendous amounts of carbon back into the atmosphere as CO2, or as increased sediment load in rivers, connected with declining water quality off-site. Affected by changed local water budget, the regional clouds' formation starts

  20. DETERMINATION OF HYDRO-ECOLOGICAL FACTORS OF THE VOLGA-CASPIAN AQUATIC ECOSYSTEMS STABILITY IN DESIGNING THEIR PROTECTION

    Directory of Open Access Journals (Sweden)

    Natalia Mitina

    2010-01-01

    Full Text Available This paper discusses possible consequences of changes in the Volga-Caspian aquatic ecosystems resulting from climate change according to the data scenarios of the Worldwide Meteorological Organization. Main hydro-ecological factors of stability of the Northern Caspian Sea ecosystems have been determined. It appears that ecosystem stability in the Northern Caspian Sea is primarily affected by natural conditions. It is essential to model riparian ecosystem processes and winter regime of reservoirs to develop strategies for mitigation of negative impacts of climate change. Such measures may include improvement of existing dams in the Volga region.

  1. Ecosystem Processes at the Watershed Scale: Stability and Resilience of Catchment Spatial Structure and Function to Disturbance

    Science.gov (United States)

    Band, L. E.

    2015-12-01

    Ecohydrological systems evolve spontaneously in response to geologic, hydroclimate and biodiversity drivers. The stability and resilience of these systems to multiple disturbances can be addressed over specific temporal extents, potentially embedded within long term transience in response to geologic or climate change. The limits of ecohydrological resilience of system state in terms of vegetation canopy and soil catenae and the space/time distribution of water, carbon and nutrient cycling is determined by a set of critical feedbacks and potential substitutions of plant functional forms in response to disturbance. The ability of forest systems to return to states functionally similar to states prior to major disturbance, or combinations of multiple disturbances, is a critical question given increasing hydroclimate extremes, biological invasions, and human disturbance. Over the past century, forest landscape ecological patterns appear to have the ability to recover from significant disturbance and re-establish similar hydrological and ecological function in humid, biodiverse regions such as the southern Appalachians, and potentially drier forest ecosystems. Understanding and prediction of past and future long term dynamics requires explicit representation of spatial and temporal feedbacks and dependencies between hydrological, ecosystem and geomorphic processes, and the spatial pattern of species or plant functional type (PFT). Comprehensive models of watershed ecohydrological resilience requires careful balance between the level of process and parameter detail between the interacting components, relative to the structure, organization, space and time scales of the landscape.

  2. How plant functional traits cascade to microbial function and ecosystem services in mountain grasslands

    Science.gov (United States)

    Lavorel, S.; Grigulis, K.; Krainer, U.; Legay, N.; Turner, C.; Dumont, M.; Kastl, E.; Arnoldi, C.; Bardgett, R.; Poly, F.; Pommier, T.; Schloter, M.; Tappeiner, U.; Bahn, M.; Clément, J.-C.

    2012-04-01

    1. There is growing evidence that plant functional diversity and microbial communities of soil are tightly coupled, and that this coupling influences a range of ecosystem functions. Moreover, it has been hypothesized that changes in the nature of interactions between plant functional diversity and microbial communities along environmental gradients contributes to variation in the delivery of ecosystem services. Although there is empirical support for such relationships using broad plant and microbial functional classifications, or from studies of plant monocultures, such relationships and their consequences for ecosystem services have not been quantified under complex field conditions with diverse plant communities. 2. We aimed to provide an explicit quantification of how plant and microbial functional properties interplay to determine key ecosystem functions underlying ecosystem services provided by grasslands. At three mountain grassland sites in the French Alps, Austrian Tyrol and northern England, we quantified, along gradients of management intensity, (i) plant functional diversity, (ii) soil microbial community composition and parameters associated with nitrogen cycling, and (iii) key ecosystem processes related to the carbon and nitrogen cycles including aboveground biomass production, standing litter, litter decomposition, soil organic matter and nitrate and ammonium leaching . Considering that plants strongly determine microbial communities, we used a hierarchical approach that considered first direct effects of plant traits and then effects of soil microorganisms on processes, to determine the relative effects of plant and microbial functional parameters on key ecosystem properties. 3. We identified a gradient of relative effects of plant and microbial traits from properties controlled mostly by aboveground processes, such as plant biomass production and standing litter, to properties controlled mostly by microbial processes, such as soil leaching of

  3. A conceptual ecosystem model of microbial communities in enhanced biological phosphorus removal plants.

    Science.gov (United States)

    Nielsen, Per Halkjaer; Mielczarek, Artur Tomasz; Kragelund, Caroline; Nielsen, Jeppe Lund; Saunders, Aaron Marc; Kong, Yunhong; Hansen, Aviaja Anna; Vollertsen, Jes

    2010-09-01

    The microbial populations in 25 full-scale activated sludge wastewater treatment plants with enhanced biological phosphorus removal (EBPR plants) have been intensively studied over several years. Most of the important bacterial groups involved in nitrification, denitrification, biological P removal, fermentation, and hydrolysis have been identified and quantified using quantitative culture-independent molecular methods. Surprisingly, a limited number of core species was present in all plants, constituting on average approx. 80% of the entire communities in the plants, showing that the microbial populations in EBPR plants are rather similar and not very diverse, as sometimes suggested. By focusing on these organisms it is possible to make a comprehensive ecosystem model, where many important aspects in relation to microbial ecosystems and wastewater treatment can be investigated. We have reviewed the current knowledge about these microorganisms with focus on key ecophysiological factors and combined this into a conceptual ecosystem model for EBPR plants. It includes the major pathways of carbon flow with specific organic substances, the dominant populations involved in the transformations, interspecies interactions, and the key factors controlling their presence and activity. We believe that the EBPR process is a perfect model system for studies of microbial ecology in water engineering systems and that this conceptual model can be used for proposing and testing theories based on microbial ecosystem theories, for the development of new and improved quantitative ecosystem models and is beneficial for future design and management of wastewater treatment systems. Copyright © 2010 Elsevier Ltd. All rights reserved.

  4. Discriminating plant species across California's diverse ecosystems using airborne VSWIR and TIR imagery

    Science.gov (United States)

    Meerdink, S.; Roberts, D. A.; Roth, K. L.

    2015-12-01

    Accurate knowledge of the spatial distribution of plant species is required for many research and management agendas that track ecosystem health. Because of this, there is continuous development of research focused on remotely-sensed species classifications for many diverse ecosystems. While plant species have been mapped using airborne imaging spectroscopy, the geographic extent has been limited due to data availability and spectrally similar species continue to be difficult to separate. The proposed Hyperspectral Infrared Imager (HyspIRI) space-borne mission, which includes a visible near infrared/shortwave infrared (VSWIR) imaging spectrometer and thermal infrared (TIR) multi-spectral imager, would present an opportunity to improve species discrimination over a much broader scale. Here we evaluate: 1) the capability of VSWIR and/or TIR spectra to discriminate plant species; 2) the accuracy of species classifications within an ecosystem; and 3) the potential for discriminating among species across a range of ecosystems. Simulated HyspIRI imagery was acquired in spring/summer of 2013 spanning from Santa Barbara to Bakersfield, CA with the Airborne Visible/Infrared Imaging Spectrometer (AVIRIS) and the MODIS/ASTER Airborne Simulator (MASTER) instruments. Three spectral libraries were created from these images: AVIRIS (224 bands from 0.4 - 2.5 µm), MASTER (8 bands from 7.5 - 12 µm), and AVIRIS + MASTER. We used canonical discriminant analysis (CDA) as a dimension reduction technique and then classified plant species using linear discriminant analysis (LDA). Our results show the inclusion of TIR spectra improved species discrimination, but only for plant species with emissivities departing from that of a gray body. Ecosystems with species that have high spectral contrast had higher classification accuracies. Mapping plant species across all ecosystems resulted in a classification with lower accuracies than a single ecosystem due to the complex nature of

  5. Global stability and persistence in LG-Holling type II diseased predator ecosystems.

    Science.gov (United States)

    Sarwardi, Sahabuddin; Haque, Mainul; Venturino, Ezio

    2011-01-01

    A Leslie-Gower-Holling type II model is modified to introduce a contagious disease in the predator population, assuming that disease cannot propagate to the prey. All the system's equilibria are determined and the behaviour of the system near them is investigated. The main mathematical issues are global stability and bifurcations for some of the equilibria, together with sufficient conditions for persistence of the ecosystem. Counterintuitive results on the role played by intraspecific competition are highlighted.

  6. Where to plant urban trees? A spatially explicit methodology to explore ecosystem service tradeoffs

    Science.gov (United States)

    E.W. Bodnaruk; C.N. Kroll; Y. Yang; S. Hirabayashi; David Nowak; T.A. Endreny

    2017-01-01

    Urban trees can help mitigate some of the environmental degradation linked to the rapid urbanization of humanity. Many municipalities are implementing ambitious tree planting programs to help remove air pollution, mitigate urban heat island effects, and provide other ecosystem services and benefits but lack quantitative tools to explore priority planting locations and...

  7. Understory flora and community physiognomy of planted forests in the degraded purple soil ecosystem, South China

    Institute of Scientific and Technical Information of China (English)

    YUZhan-yuan; YUEYong-jie; GUOJian-fen; CHENGuang-shui; XIEJin-sheng; HEZong-ming; YANGYu-sheng

    2005-01-01

    The flora and community physiognomy of degraded plantation ecosystems on purple soil were investigated in Ninghua County of Fujian Province, China to understand the relationship between plant diversity and ecosystem processes.. Four different restoration communities (labeled as ecological restoration treatment I, II, Ill and IV) were selected by space-time replacement method according to the erosion intensity in degraded purple soil ecosystem. The results showed that there were totally 86 plant species belonging to 78 genera and 43 families in the degraded purple soil ecosystem. Of the 15 types of distribution area in spermatophyte genus, 12 types were found in the purple soil ecosystem. Along restoration gradient from low to high, plant growth type and life form spectra became abundant more and more, and the spermatophyte genera for each distribution area type and genera numbers for different foliage characters increased as well. It is concluded that the plant flora and physiognomy in ecological restoration process become more complex and diverse, indicating that the forest ecosystem on purple soil tends to be more stable.

  8. The potential of novel native plant materials for the restoration of novel ecosystems

    Directory of Open Access Journals (Sweden)

    T.A. Jones

    2015-05-01

    Full Text Available Abstract Extensive ecological change has been sustained by many dryland ecosystems throughout the world, resulting in conversion to so-called novel ecosystems. It is within such ecological contexts that native plant materials destined for ecological applications must be able to function. In the Wyoming big sagebrush (Artemisia tridentata Nutt. ssp. wyomingensis [Beetle & A.M. Young] S.L. Welsh ecosystems of the Intermountain West, for example, novel ecosystem structure and functioning are pervasive. Invasive species, particularly annual grasses, fuel repeated wildfires that drive previously stable ecosystem states across thresholds to less desirable states that are highly recalcitrant to restoration efforts. Structural changes include reductions of native flora, damage to biological soil crusts, and alterations to soil microbiota. Functional changes include altered hydrologic and nutrient cycling, leading to permanent losses of soil organic matter and nitrogen that favor the invaders. We argue that there is an important place in restoration for plant materials that are novel and/or non-local that have been developed to be more effective in the novel ecosystems for which they are intended, thus qualifying them as “ecologically appropriate.” Such plant materials may be considered as an alternative to natural/local “genetically appropriate” plant materials, which are sometimes deemed best adapted due to vetting by historical evolutionary processes.

  9. Ecosystem engineering and manipulation of host plant tissues by the insect borer Oncideres albomarginata chamela.

    Science.gov (United States)

    Calderón-Cortés, Nancy; Uribe-Mú, Claudia A; Martínez-Méndez, A Karen; Escalera-Vázquez, Luis H; Cristobal-Pérez, E Jacob; García-Oliva, Felipe; Quesada, Mauricio

    2016-01-01

    Ecosystem engineering by insect herbivores occurs as the result of structural modification of plants manipulated by insects. However, only few studies have evaluated the effect of these modifications on the plant responses induced by stem-borers that act as ecosystem engineers. In this study, we evaluated the responses induced by the herbivory of the twig-girdler beetle Oncideres albomarginata chamela (Cerambycidae: Lamiinae) on its host plant Spondias purpurea (Anacardiaceae), and its relationship with the ecosystem engineering process carried out by this stem-borer. Our results demonstrated that O. albomarginata chamela branch removal induced the development of lateral branches increasing the resources needed for the development of future insect generations, of its own offspring and of many other insect species. Detached branches represent habitats with high content of nitrogen and phosphorous, which eventually can be incorporated into the ecosystem, increasing nutrient cycling efficiency. Consequently, branch removal and the subsequent plant tissue regeneration induced by O. albomarginata chamela represent key mechanisms underlying the ecosystem engineering process carried out by this stem-borer, which enhances arthropod diversity in the ecosystem.

  10. Direct and indirect effects of invasive plants on soil chemistry and ecosystem function.

    Science.gov (United States)

    Weidenhamer, Jeffrey D; Callaway, Ragan M

    2010-01-01

    Invasive plants have a multitude of impacts on plant communities through their direct and indirect effects on soil chemistry and ecosystem function. For example, plants modify the soil environment through root exudates that affect soil structure, and mobilize and/or chelate nutrients. The long-term impact of litter and root exudates can modify soil nutrient pools, and there is evidence that invasive plant species may alter nutrient cycles differently from native species. The effects of plants on ecosystem biogeochemistry may be caused by differences in leaf tissue nutrient stoichiometry or secondary metabolites, although evidence for the importance of allelochemicals in driving these processes is lacking. Some invasive species may gain a competitive advantage through the release of compounds or combinations of compounds that are unique to the invaded community—the “novel weapons hypothesis.” Invasive plants also can exert profound impact on plant communities indirectly through the herbicides used to control them. Glyphosate, the most widely used herbicide in the world, often is used to help control invasive weeds, and generally is considered to have minimal environmental impacts. Most studies show little to no effect of glyphosate and other herbicides on soil microbial communities. However, herbicide applications can reduce or promote rhizobium nodulation and mycorrhiza formation. Herbicide drift can affect the growth of non-target plants, and glyphosate and other herbicides can impact significantly the secondary chemistry of plants at sublethal doses. In summary, the literature indicates that invasive species can alter the biogeochemistry of ecosystems, that secondary metabolites released by invasive species may play important roles in soil chemistry as well as plant-plant and plant-microbe interactions, and that the herbicides used to control invasive species can impact plant chemistry and ecosystems in ways that have yet to be fully explored.

  11. Land use imperils plant and animal community stability through changes in asynchrony rather than diversity.

    Science.gov (United States)

    Blüthgen, Nico; Simons, Nadja K; Jung, Kirsten; Prati, Daniel; Renner, Swen C; Boch, Steffen; Fischer, Markus; Hölzel, Norbert; Klaus, Valentin H; Kleinebecker, Till; Tschapka, Marco; Weisser, Wolfgang W; Gossner, Martin M

    2016-01-01

    Human land use may detrimentally affect biodiversity, yet long-term stability of species communities is vital for maintaining ecosystem functioning. Community stability can be achieved by higher species diversity (portfolio effect), higher asynchrony across species (insurance hypothesis) and higher abundance of populations. However, the relative importance of these stabilizing pathways and whether they interact with land use in real-world ecosystems is unknown. We monitored inter-annual fluctuations of 2,671 plant, arthropod, bird and bat species in 300 sites from three regions. Arthropods show 2.0-fold and birds 3.7-fold higher community fluctuations in grasslands than in forests, suggesting a negative impact of forest conversion. Land-use intensity in forests has a negative net impact on stability of bats and in grasslands on birds. Our findings demonstrate that asynchrony across species--much more than species diversity alone--is the main driver of variation in stability across sites and requires more attention in sustainable management.

  12. Land use imperils plant and animal community stability through changes in asynchrony rather than diversity

    Science.gov (United States)

    Blüthgen, Nico; Simons, Nadja K.; Jung, Kirsten; Prati, Daniel; Renner, Swen C.; Boch, Steffen; Fischer, Markus; Hölzel, Norbert; Klaus, Valentin H.; Kleinebecker, Till; Tschapka, Marco; Weisser, Wolfgang W.; Gossner, Martin M.

    2016-01-01

    Human land use may detrimentally affect biodiversity, yet long-term stability of species communities is vital for maintaining ecosystem functioning. Community stability can be achieved by higher species diversity (portfolio effect), higher asynchrony across species (insurance hypothesis) and higher abundance of populations. However, the relative importance of these stabilizing pathways and whether they interact with land use in real-world ecosystems is unknown. We monitored inter-annual fluctuations of 2,671 plant, arthropod, bird and bat species in 300 sites from three regions. Arthropods show 2.0-fold and birds 3.7-fold higher community fluctuations in grasslands than in forests, suggesting a negative impact of forest conversion. Land-use intensity in forests has a negative net impact on stability of bats and in grasslands on birds. Our findings demonstrate that asynchrony across species—much more than species diversity alone—is the main driver of variation in stability across sites and requires more attention in sustainable management. PMID:26869180

  13. Plant species and functional group combinations affect green roof ecosystem functions.

    Directory of Open Access Journals (Sweden)

    Jeremy Lundholm

    Full Text Available BACKGROUND: Green roofs perform ecosystem services such as summer roof temperature reduction and stormwater capture that directly contribute to lower building energy use and potential economic savings. These services are in turn related to ecosystem functions performed by the vegetation layer such as radiation reflection and transpiration, but little work has examined the role of plant species composition and diversity in improving these functions. METHODOLOGY/PRINCIPAL FINDINGS: We used a replicated modular extensive (shallow growing- medium green roof system planted with monocultures or mixtures containing one, three or five life-forms, to quantify two ecosystem services: summer roof cooling and water capture. We also measured the related ecosystem properties/processes of albedo, evapotranspiration, and the mean and temporal variability of aboveground biomass over four months. Mixtures containing three or five life-form groups, simultaneously optimized several green roof ecosystem functions, outperforming monocultures and single life-form groups, but there was much variation in performance depending on which life-forms were present in the three life-form mixtures. Some mixtures outperformed the best monocultures for water capture, evapotranspiration, and an index combining both water capture and temperature reductions. Combinations of tall forbs, grasses and succulents simultaneously optimized a range of ecosystem performance measures, thus the main benefit of including all three groups was not to maximize any single process but to perform a variety of functions well. CONCLUSIONS/SIGNIFICANCE: Ecosystem services from green roofs can be improved by planting certain life-form groups in combination, directly contributing to climate change mitigation and adaptation strategies. The strong performance by certain mixtures of life-forms, especially tall forbs, grasses and succulents, warrants further investigation into niche complementarity or

  14. Seven years of carbon dioxide enrichment, nitrogen fertilization and plant diversity influence arbuscular mycorrhizal fungi in a grassland ecosystem.

    Science.gov (United States)

    Antoninka, Anita; Reich, Peter B; Johnson, Nancy Collins

    2011-10-01

    • We tested the prediction that the abundance and diversity of arbuscular mycorrhizal (AM) fungi are influenced by resource availability and plant community composition by examining the joint effects of carbon dioxide (CO(2) ) enrichment, nitrogen (N) fertilization and plant diversity on AM fungi. • We quantified AM fungal spores and extramatrical hyphae in 176 plots after 7 yr of treatment with all combinations of ambient or elevated CO(2) (368 or 560 ppm), with or without N fertilization (0 or 4 g Nm(-2) ), and one (monoculture) or 16 host plant species (polyculture) in the BioCON field experiment at Cedar Creek Ecosystem Science Reserve, Minnesota, USA. • Extramatrical hyphal lengths were increased by CO(2) enrichment, whereas AM spore abundance decreased with N fertilization. Spore abundance, morphotype richness and extramatrical hyphal lengths were all greater in monoculture plots. A structural equation model showed AM fungal biovolume was most influenced by CO(2) enrichment, plant community composition and plant richness, whereas spore richness was most influenced by fungal biovolume, plant community composition and plant richness. • Arbuscular mycorrhizal fungi responded to differences in host community and resource availability, suggesting that mycorrhizal functions, such as carbon sequestration and soil stability, will be affected by global change.

  15. Data analysis from monitoring of radionuclides in the nuclear power plant Temelin ecosystem area

    Energy Technology Data Exchange (ETDEWEB)

    Thinova, Lenka [Czech Technical University, Faculty of Nuclear Sciences and Physical Engineering, Department of Dosimetry, Brehova 7, 110 00 Prague (Czech Republic)], E-mail: thinova@fjfi.cvut.cz; Trojek, Tomas [Czech Technical University, Faculty of Nuclear Sciences and Physical Engineering, Department of Dosimetry, Brehova 7, 110 00 Prague (Czech Republic)

    2009-07-15

    Changes in the ecosystem occur naturally, however, can also be due to man's activity. The unique ecosystem monitoring based on studying contamination of the bioindicators by man-made radionuclides has been providing data from the area of nuclear power plant (NPP) Temelin (CR) using laboratory gamma spectrometry for past 8 years. The increase in radioactivity in the NPP ecosystem area resulting from its operation is evaluated through comparison with a zero level of {sup 137}Cs mass activities and by obtained data trend analysis.

  16. Data analysis from monitoring of radionuclides in the nuclear power plant Temelin ecosystem area.

    Science.gov (United States)

    Thinova, Lenka; Trojek, Tomas

    2009-01-01

    Changes in the ecosystem occur naturally, however, can also be due to man's activity. The unique ecosystem monitoring based on studying contamination of the bioindicators by man-made radionuclides has been providing data from the area of nuclear power plant (NPP) Temelin (CR) using laboratory gamma spectrometry for past 8 years. The increase in radioactivity in the NPP ecosystem area resulting from its operation is evaluated through comparison with a zero level of (137)Cs mass activities and by obtained data trend analysis.

  17. Invasive Plant-Soil Feedbacks and Ecosystem Resistance and Resilience: A Comparison of Three Vegetation Types in California

    OpenAIRE

    Dickens, Sara Jo Myrtle

    2010-01-01

    ABSTRACT OF THE DISSERTATIONInvasive Plant-Soil Feedbacks and Ecosystem Resistance and Resilience: A Comparison of Three Vegetation Types in CaliforniaBy Sara Jo DickensDoctor of Philosophy, Graduate Program in Plant BiologyUniversity of California, Riverside, December 2010Dr Edith B. Allen, ChairpersonEcosystem processes are strongly dependant on plant-soil feedbacks. The invasion of exotic plant species can result in the introduction of novel traits capable of de-coupling native plant-soil ...

  18. Invasive Plants Rapidly Reshape Soil Properties in a Grassland Ecosystem.

    Science.gov (United States)

    Gibbons, Sean M; Lekberg, Ylva; Mummey, Daniel L; Sangwan, Naseer; Ramsey, Philip W; Gilbert, Jack A

    2017-01-01

    Plant invasions often reduce native plant diversity and increase net primary productivity. Invaded soils appear to differ from surrounding soils in ways that impede restoration of diverse native plant communities. We hypothesize that invader-mediated shifts in edaphic properties reproducibly alter soil microbial community structure and function. Here, we take a holistic approach, characterizing plant, prokaryotic, and fungal communities and soil physicochemical properties in field sites, invasion gradients, and experimental plots for three invasive plant species that cooccur in the Rocky Mountain West. Each invader had a unique impact on soil physicochemical properties. We found that invasions drove shifts in the abundances of specific microbial taxa, while overall belowground community structure and functional potential were fairly constant. Forb invaders were generally enriched in copiotrophic bacteria with higher 16S rRNA gene copy numbers and showed greater microbial carbohydrate and nitrogen metabolic potential. Older invasions had stronger effects on abiotic soil properties, indicative of multiyear successions. Overall, we show that plant invasions are idiosyncratic in their impact on soils and are directly responsible for driving reproducible shifts in the soil environment over multiyear time scales. IMPORTANCE In this study, we show how invasive plant species drive rapid shifts in the soil environment from surrounding native communities. Each of the three plant invaders had different but consistent effects on soils. Thus, there does not appear to be a one-size-fits-all strategy for how plant invaders alter grassland soil environments. This work represents a crucial step toward understanding how invaders might be able to prevent or impair native reestablishment by changing soil biotic and abiotic properties.

  19. Exploring Third-Grade Student Model-Based Explanations about Plant Relationships within an Ecosystem

    Science.gov (United States)

    Zangori, Laura; Forbes, Cory T.

    2015-12-01

    Elementary students should have opportunities to develop scientific models to reason and build understanding about how and why plants depend on relationships within an ecosystem for growth and survival. However, scientific modeling practices are rarely included within elementary science learning environments and disciplinary content is often treated as discrete pieces separate from scientific practice. Elementary students have few, if any, opportunities to reason about how individual organisms, such as plants, hold critical relationships with their surrounding environment. The purpose of this design-based research study is to build a learning performance to identify and explore the third-grade students' baseline understanding of and their reasoning about plant-ecosystem relationships when engaged in the practices of modeling. The developed learning performance integrated scientific content and core scientific activity to identify and measure how students build knowledge about the role of plants in ecosystems through the practices of modeling. Our findings indicate that the third-grade students' ideas about plant growth include abiotic and biotic relationships. Further, they used their models to reason about how and why these relationships were necessary to maintain plant stasis. However, while the majority of the third-grade students were able to identify and reason about plant-abiotic relationships, a much smaller group reasoned about plant-abiotic-animal relationships. Implications from the study suggest that modeling serves as a tool to support elementary students in reasoning about system relationships, but they require greater curricular and instructional support in conceptualizing how and why ecosystem relationships are necessary for plant growth and development. This paper is based on data from a doctoral dissertation. An earlier version of this paper was presented at the 2015 international conference for the National Association for Research in Science

  20. Effects of roads on adjacent plant community composition and ecosystem function: An example from three calcareous ecosystems.

    Science.gov (United States)

    Lee, Mark A; Davies, Linda; Power, Sally A

    2012-04-01

    Roads and exhaust emissions can affect plant communities directly, for example via direct foliar uptake of exhaust products, or indirectly via changes to soil biogeochemistry and hydrology. A transect study adjacent to roads of different traffic densities was carried out at three species-rich calcareous grasslands in south eastern England. Measured annual NO(2) concentrations and modelled NH(3) concentrations increased towards the roads and with higher traffic densities, and there was evidence of increased soil moisture, pH and heavy metal concentrations at roadsides. Increases in the abundance of nitrogen (N) tolerant species and grasses at roadsides were associated with N enrichment from vehicle exhausts at two of the sites. In contrast plant species richness, the abundance of forb and moss species declined at roadside locations. As vehicle usage spreads across the world, it is increasingly important to understand the effects of road traffic on adjacent ecosystems to inform traffic and conservation management policies.

  1. Effects of snails, submerged plants and their coexistence on eutrophication in aquatic ecosystems

    Directory of Open Access Journals (Sweden)

    Mo Shuqing

    2017-01-01

    Full Text Available Eutrophication resulting from nutrient loading to freshwater habitats is a severe problem, leading to degradation of ecosystems, including deterioration of water quality, water clarity and loss of biodiversity. Measures enacted to restore degraded freshwater ecosystems often involve the reintroduction of submerged plants and aquatic animals with beneficial ecological functions. In a mesocosm experiment, three treatments (planting with Vallisneria natans, introduction of the snail Bellamya aeruginosa and a combined treatment with both plants and snails were compared with controls to evaluate their effects on trophic state. The total nitrogen (TN, total phosphorus (TP and chlorophyll a (Chl a concentrations of planktonic and benthic algal samples were determined every two weeks, along with light intensity at the sediment surface. The plant-only treatment significantly reduced the TN levels and planktonic and benthic algal biomass and increased the light intensity at the sediment surface. The snail-only treatment reduced the concentrations of TN and reduced planktonic and benthic algal biomass. The combined treatment decreased the concentrations of TN and TP, reduced planktonic algal biomass and increased the light intensity on the sediment surface. The results indicate that while submerged plants and snails can both improve water quality, the most pronounced effect in aquatic ecosystems is achieved by their presence in combination. A combined reintroduction approach may provide enhanced benefits in restoring the eutrophic ecosystems, following the reduction of external nutrient loading.

  2. Climate change alters stability and species potential interactions in a large marine ecosystem.

    Science.gov (United States)

    Griffith, Gary P; Strutton, Peter G; Semmens, Jayson M

    2017-09-04

    We have little empirical evidence of how large-scale overlaps between large numbers of marine species may have altered in response to human impacts. Here, we synthesized all available distribution data (>1 million records) since 1992 for 61 species of the East Australian marine ecosystem, a global hot spot of ocean warming and continuing fisheries exploitation. Using a novel approach, we constructed networks of the annual changes in geographical overlaps between species. Using indices of changes in species overlap, we quantified changes in the ecosystem stability, species robustness, species sensitivity and structural keystone species. We then compared the species overlap indices with environmental and fisheries data to identify potential factors leading to the changes in distributional overlaps between species. We found that the structure of the ecosystem has changed with a decrease in asymmetrical geographical overlaps between species. This suggests that the ecosystem has become less stable and potentially more susceptible to environmental perturbations. Most species have shown a decrease in overlaps with other species. The greatest decrease in species overlap robustness and sensitivity to the loss of other species has occurred in the pelagic community. Some demersal species have become more robust and less sensitive. Pelagic structural keystone species, predominately the tunas and billfish, have been replaced by demersal fish species. The changes in species overlap were strongly correlated with regional oceanographic changes, in particular increasing ocean warming and the southward transport of warmer and saltier water with the East Australian Current (EAC), but less correlated with fisheries catch. Our study illustrates how large-scale multispecies distribution changes can help identify structural changes in marine ecosystems associated with climate change. This article is protected by copyright. All rights reserved. This article is protected by copyright. All

  3. Ecosystem Responses To Plant Phenology Across Scales And Trophic Levels

    Science.gov (United States)

    Stoner, D.; Sexton, J. O.; Nagol, J. R.; Ironside, K.; Choate, D.; Longshore, K.; Edwards, T., Jr.

    2015-12-01

    Plant phenology in arid and semi-arid ecoregions is constrained by water availability and governs the life history characteristics of primary and secondary consumers. We related the behavior, demography, and distribution of mammalian herbivores and their principal predator to remotely sensed vegetation and climatological indices across the western United States for the period 2000-2014. Across scales, terrain and topographic position moderates the effects of climatological drought on primary productivity, resulting in differential susceptibility among plant functional types to water stress. At broad scales, herbivores tie parturition to moist sites during the period of maximum increase in local forage production. Consequently, juvenile mortality is highest in regions of extreme phenological variability. Although decoupled from primary production by one or more trophic levels, carnivore home range size and density is negatively correlated to plant productivity and growing season length. At the finest scales, predation influences the behavior of herbivore prey through compromised habitat selection, in which maternal females trade nutritional benefits of high plant biomass for reduced mortality risk associated with increased visibility. Climate projections for the western United States predict warming combined with shifts in the timing and form of precipitation. Our analyses suggest that these changes will propagate through trophic levels as increased phenological variability and shifts in plant distributions, larger consumer home ranges, altered migration behavior, and generally higher volatility in wildlife populations. Combined with expansion and intensification of human land use across the region, these changes will likely have economic implications stemming from increased human-wildlife conflict (e.g., crop damage, vehicle collisions) and changes in wildlife-related tourism.

  4. Environmental risk assessment for plant pests: a procedure to evaluate their impacts on ecosystem services

    DEFF Research Database (Denmark)

    Gilioli, G.; Schrader, G.; Baker, R.H.A.

    2014-01-01

    The current methods to assess the environmental impacts of plant pests differ in their approaches and there is a lack of the standardized procedures necessary to provide accurate and consistent results, demonstrating the complexity of developing a commonly accepted scheme for this purpose....... By including both the structural and functional components of the environment threatened by invasive alien species (IAS), in particular plant pests, we propose an environmental risk assessment scheme that addresses this complexity. Structural components are investigated by evaluating the impacts of the plant...... pest on genetic, species and landscape diversity. Functional components are evaluated by estimating how plant pests modify ecosystem services in order to determine the extent to which an IAS changes the functional traits that influence ecosystem services. A scenario study at a defined spatial...

  5. Feedbacks Between Microenvironment and Plant Functional Type and Implications for CO2 Flux in Arctic Ecosystems

    Science.gov (United States)

    Squires, E.; Rodenheizer, H.; Natali, S.; Mann, P.

    2013-12-01

    Future climate models predict a warmer, drier Arctic, with resultant shifts in vegetative composition and implications for ecosystem carbon budgets. The impact of vegetation change, however, may depend on which plant functional groups are favored in a warming Arctic. Physiological and functional differences between plant groups influence both the local microenvironment and, on a broader scale, whole-ecosystem CO2 flux. We examined the interactions between plants and their microenvironment, and analyzed the effect of these interactions on both soil microbial communities and CO2 flux across different functional groups. Physical and biological aspects of the microenvironment differed between plant functional groups. Lichen patches were characterized by deeper thaw depths, lower soil moisture, greater thermal conductivity, and a thinner organic layer than mosses. To better understand the development of these plant-environment interactions, we conducted a reciprocal transplant experiment, switching multiple lichen and moss patches. Temporal changes in environmental parameters at these sites will demonstrate how different plants modify their environment and will help identify associated implications for soil microbial communities and CO2 flux. We measured CO2 flux and used Biolog assays to examine soil microbial communities in undisturbed patches of mosses, lichens, and shrubs. Patches of birch shrubs had more negative net ecosystem exchange, signifying a carbon sink. Soils from alder shrubs and mosses hosted more active microbial communities than soils under birch shrubs and lichens. These results suggest a strong link between environment, plant functional type, and C cycling. Understanding how this relationship differs among plant functional types is an important part of predicting ecosystem carbon budgets as Arctic vegetation composition shifts in response to climate change.

  6. Modeling the response of plants and ecosystems to elevated CO{sub 2} and climate change

    Energy Technology Data Exchange (ETDEWEB)

    Reynolds, J.F.; Hilbert, D.W.; Chen, Jia-lin; Harley, P.C.; Kemp, P.R.; Leadley, P.W.

    1992-03-01

    While the exact effects of elevated CO{sub 2} on global climate are unknown, there is a growing consensus among climate modelers that global temperature and precipitation will increase, but that these changes will be non-uniform over the Earth`s surface. In addition to these potential climatic changes, CO{sub 2} also directly affects plants via photosynthesis, respiration, and stomatal closure. Global climate change, in concert with these direct effects of CO{sub 2} on plants, could have a significant impact on both natural and agricultural ecosystems. Society`s ability to prepare for, and respond to, such changes depends largely on the ability of climate and ecosystem researchers to provide predictions of regional level ecosystem responses with sufficient confidence and adequate lead time.

  7. Modeling the response of plants and ecosystems to elevated CO sub 2 and climate change

    Energy Technology Data Exchange (ETDEWEB)

    Reynolds, J.F.; Hilbert, D.W.; Chen, Jia-lin; Harley, P.C.; Kemp, P.R.; Leadley, P.W.

    1992-03-01

    While the exact effects of elevated CO{sub 2} on global climate are unknown, there is a growing consensus among climate modelers that global temperature and precipitation will increase, but that these changes will be non-uniform over the Earth's surface. In addition to these potential climatic changes, CO{sub 2} also directly affects plants via photosynthesis, respiration, and stomatal closure. Global climate change, in concert with these direct effects of CO{sub 2} on plants, could have a significant impact on both natural and agricultural ecosystems. Society's ability to prepare for, and respond to, such changes depends largely on the ability of climate and ecosystem researchers to provide predictions of regional level ecosystem responses with sufficient confidence and adequate lead time.

  8. Exploring Third-Grade Student Model-Based Explanations about Plant Relationships within an Ecosystem

    Science.gov (United States)

    Zangori, Laura; Forbes, Cory T.

    2015-01-01

    Elementary students should have opportunities to develop scientific models to reason and build understanding about how and why plants depend on relationships within an ecosystem for growth and survival. However, scientific modeling practices are rarely included within elementary science learning environments and disciplinary content is often…

  9. [Ecological control effects of Litchi chinensis-Desmodium intortum complex plant ecosystem on litchi pests].

    Science.gov (United States)

    Ouyang, Gecheng; Yang, Yueping; Liu, Deguang; Xiong, Jinjun; Huang, Mingdu

    2006-01-01

    An investigation on the community structure and dynamics of litchi pests and their natural enemies in constructed Litchi chinensis-Desmodium intortum complex plant ecosystem and single L. chinensis ecosystem showed that the total amount of litchi pests in the complex plant ecosystem was 61.27% of that in the single ecosystem in whole year, and only 50.45% in May, the key time for fruit development, which suggested that there was an interaction between D. intortum and L. chinensis. D. intortum and L. chinensis had a few common pests, but many common natural enemies. D. intortum florescence in winter provided shelter and substitutive food for the natural enemies of pests to survive in the extreme environmental conditions in winter. L. chinensis florescence was on the heel of D. intortum florescence, which provided better conditions for the natural enemies to survive and multiply. During florescence and fruit development stages of L. chinensis (from March to June), the predator/prey ratio in complex plant system was 4.22, 2.34, 2.2 and 20.63 times of that in single plant system in March, April, May and June, respectively, indicating the good control effect on pests of L. chinensis.

  10. Patterns of Genetic Variation in Woody Plant Species in the Missouri Ozark Forest Ecosystem Project

    Science.gov (United States)

    Victoria L. Sork; Anthony Koop; Marie Ann de la Fuente; Paul Foster; Jay. Raveill

    1997-01-01

    We quantified current patterns of genetic variation of three woody plant species—Carya tomentosa (Juglandaceae), Quercus alba (Fagaceae), and Sassafras albidum (Lauraceae)—distributed throughout the nine Missouri Ozark Forest Ecosystem Project (MOFEP) study sites and evaluated the data in light of the MOFEP...

  11. Dynamic stability of communities of amphibians in short-term-flooded forest ecosystems

    Directory of Open Access Journals (Sweden)

    O. V. Zhukov

    2015-09-01

    Full Text Available The estimation of stability of amphibian populations on the basis of data of population dynamics is given. The paper shows an attempt to estimate the direction of dynamic changes of amphibian populations, and defines the rate of the system deviation from the stationary state due to possible influence of the environmental factors by using concepts such as reactivity, degree of reactivity and flexibility of the system when using their indexes. It is found that populations of amphibians are quite stable with regard to quantifying these species. Characteristic feature is the elasticity of the system. It is confirmed by the elasticity of the system species Bufo bufo (Linnaeus, 1758. TypePelobates fuscus (Laurenti, 1768 is defined as a factor of stability of the system in quantitative terms. Dependenceof dynamics of the population on its size is established using the regression equation. Dynamics of groups depends on the action of possible predictors in response to which the population of B. bufo is not changed. The ecosystem is characterized as a place of interaction between biotic factors and factors of abiotic origin, which are due to the external action. Internal factor of the ecosystem stability is the influence of some amphibian populations on the other ones. The system features sustainable and relatively stable number of B. bufo, which does not affect the level of its stability. Stationary state of the grouping is unstable due to dynamic matrix, which describes the behavior of the group in the vicinity of the first stationary state. The second steady state is stableone, and the system returns to the stationary state with the help of wave-like dynamics. On the basis of our study it is established that the number of groups of amphibians remains stable, the systems behave differently, and dynamics of their return to the stationary state is elastic or reactive one. Еcosystems within lime-ash oak forests in the Central floodplain of the Samarariver

  12. Cross-ecosystem comparisons of in situ plant uptake of amino acid-N and NH4+

    Science.gov (United States)

    Jack W. McFarland; Roger W. Ruess; Knut Kielland; Kurt Pregitzer; Ronald Hendrick; Michael. Allen

    2010-01-01

    Plant and microbial use of nitrogen (N) can be simultaneously mutualistic and competitive, particularly in ecosystems dominated by mycorrhizal fungi. Our goal was to quantify plant uptake of organic and inorganic N across a broad latitudinal gradient of forest ecosystems that varied with respect to overstory taxon, edaphic characteristics, and dominant mycorrhizal...

  13. Plant hydraulics as a central hub integrating plant and ecosystem function: meeting report for 'Emerging Frontiers in Plant Hydraulics' (Washington, DC, May 2015).

    Science.gov (United States)

    Sack, Lawren; Ball, Marilyn C; Brodersen, Craig; Davis, Stephen D; Des Marais, David L; Donovan, Lisa A; Givnish, Thomas J; Hacke, Uwe G; Huxman, Travis; Jansen, Steven; Jacobsen, Anna L; Johnson, Daniel M; Koch, George W; Maurel, Christophe; McCulloh, Katherine A; McDowell, Nate G; McElrone, Andrew; Meinzer, Frederick C; Melcher, Peter J; North, Gretchen; Pellegrini, Matteo; Pockman, William T; Pratt, R Brandon; Sala, Anna; Santiago, Louis S; Savage, Jessica A; Scoffoni, Christine; Sevanto, Sanna; Sperry, John; Tyerman, Stephen D; Way, Danielle; Holbrook, N Michele

    2016-09-01

    Water plays a central role in plant biology and the efficiency of water transport throughout the plant affects both photosynthetic rate and growth, an influence that scales up deterministically to the productivity of terrestrial ecosystems. Moreover, hydraulic traits mediate the ways in which plants interact with their abiotic and biotic environment. At landscape to global scale, plant hydraulic traits are important in describing the function of ecological communities and ecosystems. Plant hydraulics is increasingly recognized as a central hub within a network by which plant biology is connected to palaeobiology, agronomy, climatology, forestry, community and ecosystem ecology and earth-system science. Such grand challenges as anticipating and mitigating the impacts of climate change, and improving the security and sustainability of our food supply rely on our fundamental knowledge of how water behaves in the cells, tissues, organs, bodies and diverse communities of plants. A workshop, 'Emerging Frontiers in Plant Hydraulics' supported by the National Science Foundation, was held in Washington DC, 2015 to promote open discussion of new ideas, controversies regarding measurements and analyses, and especially, the potential for expansion of up-scaled and down-scaled inter-disciplinary research, and the strengthening of connections between plant hydraulic research, allied fields and global modelling efforts.

  14. Maintenance of genome stability in plants: repairing DNA double strand breaks and chromatin structure stability

    Directory of Open Access Journals (Sweden)

    Sujit eRoy

    2014-09-01

    Full Text Available Plant cells are subject to high levels of DNA damage resulting from plant’s obligatory dependence on sunlight and the associated exposure to environmental stresses like solar UV radiation, high soil salinity, drought, chilling injury and other air and soil pollutants including heavy metals and metabolic byproducts from endogenous processes. The irreversible DNA damages, generated by the environmental and genotoxic stresses affect plant growth and development, reproduction and crop productivity. Thus, for maintaining genome stability, plants have developed an extensive array of mechanisms for the detection and repair of DNA damages. This review will focus recent advances in our understanding of mechanisms regulating plant genome stability in the context of repairing of double stand breaks and chromatin structure maintenance.

  15. Plant responses, climate pivot points, and trade-offs in water-limited ecosystems

    Science.gov (United States)

    Munson, Seth M.

    2013-01-01

    Plant species in dryland ecosystems are limited by water availability and may be vulnerable to increases in aridity. Methods are needed to monitor and assess the rate of change in plant abundance and composition in relation to climate, understand the potential for degradation in dryland ecosystems, and forecast future changes in plant species assemblages. I employ nearly a century of vegetation monitoring data from three North American deserts to demonstrate an approach to determine plant species responses to climate and critical points over a range of climatic conditions at which plant species shift from increases to decreases in abundance (climate pivot points). I assess these metrics from a site to regional scale and highlight how these indicators of plant performance can be modified by the physical and biotic environment. For example, shrubs were more responsive to drought and high temperatures on shallow soils with limited capacity to store water and fine-textured soils with slow percolation rates, whereas perennial grasses were more responsive to precipitation in sparse shrublands than in relatively dense grasslands and shrublands, where competition for water is likely more intense. The responses and associated climate pivot points of plant species aligned with their lifespan and structural characteristics, and the relationship between responses and climate pivot points provides evidence of the trade-off between the capacity of a plant species to increase in abundance when water is available and its drought resistance.

  16. Uncovering the contribution of epigenetics to plant phenotypic variation in Mediterranean ecosystems.

    Science.gov (United States)

    Balao, F; Paun, O; Alonso, C

    2017-06-21

    Epigenetic signals can affect plant phenotype and fitness and be stably inherited across multiple generations. Epigenetic regulation plays a key role in the mechanisms of plant response to the environment, without altering DNA sequence. As plants cannot adapt behaviourally or migrate instantly, such dynamic epigenetic responses may be particularly crucial for survival of plants within changing and challenging environments, such as the Mediterranean-Type Ecosystems (MTEs). These ecosystems suffer recurrent stressful events (warm and dry summers with associated fire regimes) that have selected for plants with similar phenotypic complex traits, resulting in similar vegetation growth forms. However, the potential role of epigenetics in plant adaptation to recurrent stressful environments such as the MTEs has generally been ignored. To understand the full spectrum of adaptive processes in such contexts, it is imperative to prompt study of the causes and consequences of epigenetic variation in natural populations. With this purpose, we review here current knowledge on epigenetic variation in natural populations and the genetic and epigenetic basis of some key traits for plants in the MTEs, namely those traits involved in adaptation to drought, fire and oligotrophic soils. We conclude there is still much to be learned about 'plant epigenetics in the wild' and, thus, we propose future research steps in the study of natural epigenetic variation of key traits in the MTEs at different scales. © 2017 German Botanical Society and The Royal Botanical Society of the Netherlands.

  17. Alien Roadside Species More Easily Invade Alpine than Lowland Plant Communities in a Subarctic Mountain Ecosystem

    Science.gov (United States)

    Lembrechts, Jonas J.; Milbau, Ann; Nijs, Ivan

    2014-01-01

    Effects of roads on plant communities are not well known in cold-climate mountain ecosystems, where road building and development are expected to increase in future decades. Knowledge of the sensitivity of mountain plant communities to disturbance by roads is however important for future conservation purposes. We investigate the effects of roads on species richness and composition, including the plant strategies that are most affected, along three elevational gradients in a subarctic mountain ecosystem. We also examine whether mountain roads promote the introduction and invasion of alien plant species from the lowlands to the alpine zone. Observations of plant community composition were made together with abiotic, biotic and anthropogenic factors in 60 T-shaped transects. Alpine plant communities reacted differently to road disturbances than their lowland counterparts. On high elevations, the roadside species composition was more similar to that of the local natural communities. Less competitive and ruderal species were present at high compared with lower elevation roadsides. While the effects of roads thus seem to be mitigated in the alpine environment for plant species in general, mountain plant communities are more invasible than lowland communities. More precisely, relatively more alien species present in the roadside were found to invade into the surrounding natural community at high compared to low elevations. We conclude that effects of roads and introduction of alien species in lowlands cannot simply be extrapolated to the alpine and subarctic environment. PMID:24586947

  18. WAYS OF STABILIZATION THE ENERGY OF SMALL HYDROPOWER PLANTS

    Directory of Open Access Journals (Sweden)

    Vinnikov A. V.

    2015-10-01

    Full Text Available The article deals with the basic methods of stabilizing voltage generators for small hydroelectric power plants. It shows a block diagram of the implementation and analysis of the characteristics of the work; it reveals the advantages and disadvantages. The authors explain the features of the work of the functional circuits voltage regulators with discrete ballast, with phase control and management of the load current. It is shown, that to improve the performance of small hydroelectric power plants considerably we have to use contactless generators in their construction: asynchronous generators with capacitive excitation and synchronous generators with permanent magnets. The functional scheme of the voltage regulator, the construction of which has an additional field winding, simplifies the system voltage stabilization of the synchronous generator with permanent magnets, as well as a functional scheme of an asynchronous generator voltage regulator, made using step-up transformers, which significantly reduces the weight of the capacitors providing excitation of the generator and compensation of reactive power load. We have discussed the methods and devices for stabilization of voltage generators which will improve the effectiveness of pre-design work on the creation of new devices of stabilization of parameters of electric power generators for small hydroelectric power plants with improved operational and technical specifications

  19. Cascading effects of long-term land-use changes on plant traits and ecosystem functioning.

    Science.gov (United States)

    Laliberté, Etienne; Tylianakis, Jason M

    2012-01-01

    There is much concern that the functioning of ecosystems will be affected by human-induced changes in biodiversity, of which land-use change is the most important driver. However, changes in biodiversity may be only one of many pathways through which land use alters ecosystem functioning, and its importance relative to other pathways remains unclear. In particular, although biodiversity-ecosystem function research has focused primarily on grasslands, the increases in agricultural inputs (e.g., fertilization, irrigation) and grazing pressure that drive change in grasslands worldwide have been largely ignored. Here we show that long-term (27-year) manipulations of soil resource availability and sheep grazing intensity caused marked, consistent shifts in grassland plant functional composition and diversity, with cascading (i.e., causal chains of) direct, indirect, and interactive effects on multiple ecosystem functions. Resource availability exerted dominant control over above-ground net primary production (ANPP), both directly and indirectly via shifts in plant functional composition. Importantly, the effects of plant functional diversity and grazing intensity on ANPP shifted from negative to positive as agricultural inputs increased, providing strong evidence that soil resource availability modulates the impacts of plant diversity and herbivory on primary production. These changes in turn altered litter decomposition and, ultimately, soil carbon sequestration, highlighting the relevance of ANPP as a key integrator of ecosystem functioning. Our study reveals how human alterations of bottom-up (resources) and top-down (herbivory) forces together interact to control the functioning of grazing systems, the most extensive land use on Earth.

  20. The effect of higher plant microflora on the microbial landscape of a closed ecosystem

    Science.gov (United States)

    Tirranen, Lyalya; Gitelson, Josef; Borodina, Elena

    2012-07-01

    Having summarized certain data obtained earlier, we defined the aim of this work as an estimation of the effect of higher plant microflora on the microbial landscape of a closed ecosystem (CES). The microflora of such a component as higher plants can influence other system components not only by way of transfer with air and water flows, but also through the direct contact of the crew with the crops cultivated within CES when harvesting, thrashing, using them for food. Involving the higher plant component into the closed system the microorganism diversity and occurrence of microscopic fungi in other components of the closed ecosystem increased. The presence of microscopic fungi, especially on plants and in the air, is potentially dangerous for the health of the system residents. Since the contribution of the higher plant microflora (especially mycoflora) to the microbial landscape of a CES is significant, it is necessary to reduce the microbial flora of the higher plant component and limit its dispersion to other system components. One of the possible measures to limit the higher plant microflora colonization is air purification between components. Reducing the number of microscopic fungi by decreasing the humidity in the system's atmosphere should also be considered.

  1. Estimation of root cohesion for desert shrub species in the Lower Colorado riparian ecosystem and its potential for streambank stabilization

    Science.gov (United States)

    Adhikari, A. R.; Gautam, M. R.; Yu, Z.; Imada, S.; Acharya, K.

    2012-12-01

    Quantifying mechanical properties of native vegetation for streambank stability has remained a critical need of the Lower Colorado riparian revegetation effort. In the present study we estimated root cohesion for four representative native desert shrub species: Artiplex lentiformis (Torr.) S.Watson, Lycium andersonii A. Gray, Larrea tridentata (DC.) Coville, and Allenrolfea occidentalis (S.Watson) Kuntze to understand their suitability in streambank stabilization in the framework of a revegetation campaign. Field experiments were conducted to measure root length, root length density, root area ratio, and root tensile strength. Finally, the root cohesion values were assessed using a simple perpendicular model. Root area ratio estimates showed that on average plant roots occupy 0.46 % of the area under the crown of the selected species. The root tensile strength (Tr) was greatest for L. tridentata (62.23 MPa) followed by L. andersonii (53.53 MPa), A. lentiformis (49.17 MPa), and A. occidentalis (35.03 MPa).The root cohesion values could be used to rank the species according to their potential for shallow bank slope stabilization in riparian ecosystems of a desert environment. The maximum root cohesion in the present study was estimated for A. lentiformis (97.6kPa) followed by L. andersonii (89.3kPa), L. tridentata (35.6 kPa), and A. occidentalis (34.8 kPa). Root cohesion values were also estimated using Fiber bundle model (FBM) and compared to the perpendicular root model of Wu et al. (1979). The comparative root cohesion values for root diameter (> 0.5 mm) suggest that Wu's model estimates are greater than those of the FBM model by a reduction factor ranges between 0.35 and 0.56 for our studied species.

  2. Implementing plant biostimulants and biocontrol strategies in the agroecological management of cultivated ecosystems. A review

    Directory of Open Access Journals (Sweden)

    Le Mire, G.

    2016-01-01

    Full Text Available Introduction. In the context of sustainable agricultural production, agroecology aims at optimizing the economic and environmental performances of beneficial ecosystem services in order to (i increase the productivity and resilience of cultivated ecosystems and (ii preserve their natural resources. The maintenance of such performances is supported by research via the development of new tools that enhance plant tolerance to numerous biotic and abiotic stresses. Literature. Biostimulants can be used as a tool to complement the use of chemical inputs, by involving non-living-based products, or living-based products containing beneficial rhizosphere microbiome, such as plant growth-promoting rhizobacteria (PGPR. Pest management research has also made major advances in the development of efficient biocontrol methods. Elicitors and semiochemicals are considered to be some of the most promising tools for inducing plant resistance to various diseases and enhancing natural predation, respectively. Several products are already on the market. This review discusses current methods for exploiting and applying biostimulant and biocontrol products in contemporary agricultural systems. Future applications of these tools for sustainable management of cultivated ecosystems are also discussed. Conclusions. These tools are still difficult to use because of their lack of reliability in the field and their uneasy integration in the cropping systems. Further studies are needed to better understand the parameters influencing the efficiency of PGPR, elicitors and semiochemicals. Special attention needs to be given to the formulation and the interactions of these products with plant physiology and the environment.

  3. The importance of individuals: intraspecific diversity of mycorrhizal plants and fungi in ecosystems.

    Science.gov (United States)

    Johnson, David; Martin, Francis; Cairney, John W G; Anderson, Ian C

    2012-05-01

    A key component of biodiversity is the number and abundance of individuals (i.e. genotypes), and yet such intraspecific diversity is rarely considered when investigating the effects of biodiversity of mycorrhizal plants and fungi on ecosystem processes. Within a species, individuals vary considerably in important reproductive and functional attributes, including carbon fixation, mycelial growth and nutrient utilization, but this is driven by both genetic and environmental (including climatic) factors. The interactions between individual plants and mycorrhizal fungi can have important consequences for the maintenance of biodiversity and regulation of resource transfers in ecosystems. There is also emerging evidence that assemblages of genotypes may affect ecosystem processes to a similar extent as assemblages of species. The application of whole-genome sequencing and population genomics to mycorrhizal plants and fungi will be crucial to determine the extent to which individual variation in key functional attributes is genetically based. We argue the need to unravel the importance of the diversity (especially assemblages of different evenness and richness) of individuals of both mycorrhizal plants and fungi, and the need to take a 'community genetics' approach to better understand the functional significance of the biodiversity of mycorrhizal symbioses. © 2012 The Authors. New Phytologist © 2012 New Phytologist Trust.

  4. Ecosystem services and plant physiological status during endophyte-assisted phytoremediation of metal contaminated soil.

    Science.gov (United States)

    Burges, Aritz; Epelde, Lur; Blanco, Fernando; Becerril, José M; Garbisu, Carlos

    2017-04-15

    Mining sites shelter a characteristic biodiversity with large potential for the phytoremediation of metal contaminated soils. Endophytic plant growth-promoting bacteria were isolated from two metal-(hyper)accumulator plant species growing in a metal contaminated mine soil. After characterizing their plant growth-promoting traits, consortia of putative endophytes were used to carry out an endophyte-assisted phytoextraction experiment using Noccaea caerulescens and Rumex acetosa (singly and in combination) under controlled conditions. We evaluated the influence of endophyte-inoculated plants on soil physicochemical and microbial properties, as well as plant physiological parameters and metal concentrations. Data interpretation through the grouping of soil properties within a set of ecosystem services was also carried out. When grown together, we observed a 41 and 16% increase in the growth of N. caerulescens and R. acetosa plants, respectively, as well as higher values of Zn phytoextraction and soil microbial biomass and functional diversity. Inoculation of the consortia of putative endophytes did not lead to higher values of plant metal uptake, but it improved the plants' physiological status, by increasing the content of chlorophylls and carotenoids by up to 28 and 36%, respectively, indicating a reduction in the stress level of plants. Endophyte-inoculation also stimulated soil microbial communities: higher values of acid phosphatase activity (related to the phosphate solubilising traits of the endophytes), bacterial and fungal abundance, and structural diversity. The positive effects of plant growth and endophyte inoculation on soil properties were reflected in an enhancement of some ecosystem services (biodiversity, nutrient cycling, water flow regulation, water purification and contamination control).

  5. Terrestrial ecosystems response to climate and climate change: plant migration and the future of forested systems

    Science.gov (United States)

    Flanagan, S.; Hurtt, G. C.; Fisk, J.; Sahajpal, R.

    2013-12-01

    Climate change alters ecosystem structure and type. A robust understanding of climate-ecosystem relationships can be used to forecast ecosystem structure and distribution from climate change. However, current efforts to forecast future carbon sequestration rates often oversimplify or overlook the role of plant migration and focus on potential vegetation. The difficulty in accounting for landscape complexity, disturbance rates, species-specific interactions, and dispersal properties leads to this oversimplification or non-inclusion of migration when forecasting. Forest gap models can capture many of these processes, but are limited in the size of the domain they simulate because of computational time. For large scale simulations a gap model is often used to represent a much larger domain, potentially failing to capture a number of ecosystem processes as a 30m by 30m gap model may be used to represent a 0.5 x 0.5 degree site. Another method to model migration is to simply leave a fraction of every seed type in every site, which only generates scenarios that represent maximum migration rates. As a solution to these problems we introduced a migration function to the Ecosystem Demography (ED) model. ED is an individual tree based model that uses a size and age-structured approximation for the first moment of the stochastic ecosystem model. Hence it can simulate large domains without being too computational intensive. However, explicit locations of individual trees in a site are unknown, just the total number of trees in the site. Therefore, we developed a method to pseudo-spatially model migration. A simple simulator was built and it was shown that over a large number of runs expected migration rates can be reproduced. The simulator was placed into ED and climate change scenarios run. With fitted species-specific dispersal kernels the role that plant migration will play in the future of forested systems in North America was identified. Issues that still need to be

  6. A large-scale forest fragmentation experiment: the Stability of Altered Forest Ecosystems Project.

    Science.gov (United States)

    Ewers, Robert M; Didham, Raphael K; Fahrig, Lenore; Ferraz, Gonçalo; Hector, Andy; Holt, Robert D; Kapos, Valerie; Reynolds, Glen; Sinun, Waidi; Snaddon, Jake L; Turner, Edgar C

    2011-11-27

    Opportunities to conduct large-scale field experiments are rare, but provide a unique opportunity to reveal the complex processes that operate within natural ecosystems. Here, we review the design of existing, large-scale forest fragmentation experiments. Based on this review, we develop a design for the Stability of Altered Forest Ecosystems (SAFE) Project, a new forest fragmentation experiment to be located in the lowland tropical forests of Borneo (Sabah, Malaysia). The SAFE Project represents an advance on existing experiments in that it: (i) allows discrimination of the effects of landscape-level forest cover from patch-level processes; (ii) is designed to facilitate the unification of a wide range of data types on ecological patterns and processes that operate over a wide range of spatial scales; (iii) has greater replication than existing experiments; (iv) incorporates an experimental manipulation of riparian corridors; and (v) embeds the experimentally fragmented landscape within a wider gradient of land-use intensity than do existing projects. The SAFE Project represents an opportunity for ecologists across disciplines to participate in a large initiative designed to generate a broad understanding of the ecological impacts of tropical forest modification.

  7. Plant functional traits in relation to fire in crown-fire ecosystems

    Science.gov (United States)

    Pausas, Juli G.; Bradstock, Ross A.; Keith, David A.; Keeley, Jon E.

    2004-01-01

    Disturbance is a dominant factor in many ecosystems, and the disturbance regime is likely to change over the next decades in response to land-use changes and global warming. We assume that predictions of vegetation dynamics can be made on the basis of a set of life-history traits that characterize the response of a species to disturbance. For crown-fire ecosystems, the main plant traits related to postfire persistence are the ability to resprout (persistence of individuals) and the ability to retain a persistent seed bank (persistence of populations). In this context, we asked (1) to what extent do different life-history traits co-occur with the ability to resprout and/or the ability to retain a persistent seed bank among differing ecosystems and (2) to what extent do combinations of fire-related traits (fire syndromes) change in a fire regime gradient? We explored these questions by reviewing the literature and analyzing databases compiled from different crown-fire ecosystems (mainly eastern Australia, California, and the Mediterranean basin). The review suggests that the pattern of correlation between the two basic postfire persistent traits and other plant traits varies between continents and ecosystems. From these results we predict, for instance, that not all resprouters respond in a similar way everywhere because the associated plant traits of resprouter species vary in different places. Thus, attempts to generalize predictions on the basis of the resprouting capacity may have limited power at a global scale. An example is presented for Australian heathlands. Considering the combination of persistence at individual (resprouting) and at population (seed bank) level, the predictive power at local scale was significantly increased.

  8. Potential ecosystem service delivery by endemic plants in New Zealand vineyards: successes and prospects

    Directory of Open Access Journals (Sweden)

    Morgan W. Shields

    2016-06-01

    Full Text Available Vineyards worldwide occupy over 7 million hectares and are typically virtual monocultures, with high and costly inputs of water and agro-chemicals. Understanding and enhancing ecosystem services can reduce inputs and their costs and help satisfy market demands for evidence of more sustainable practices. In this New Zealand work, low-growing, endemic plant species were evaluated for their potential benefits as Service Providing Units (SPUs or Ecosystem Service Providers (ESPs. The services provided were weed suppression, conservation of beneficial invertebrates, soil moisture retention and microbial activity. The potential Ecosystem Dis-services (EDS from the selected plant species by hosting the larvae of a key vine moth pest, the light-brown apple moth (Epiphyas postvittana, was also quantified. Questionnaires were used to evaluate winegrowers’ perceptions of the value of and problems associated with such endemic plant species in their vineyards. Growth and survival rates of the 14 plant species, in eight families, were evaluated, with Leptinella dioica (Asteraceae and Acaena inermis ‘purpurea’ (Rosaceae having the highest growth rates in terms of area covered and the highest survival rate after 12 months. All 14 plant species suppressed weeds, with Leptinella squalida, Geranium sessiliforum (Geraniaceae, Hebe chathamica (Plantaginaceae, Scleranthus uniflorus (Caryophyllaceae and L. dioica, each reducing weed cover by >95%. Plant species also differed in the diversity of arthropods that they supported, with the Shannon Wiener diversity index (H′ for these taxa ranging from 0 to 1.3. G. sessiliforum and Muehlenbeckia axillaris (Polygonaceae had the highest invertebrate diversity. Density of spiders was correlated with arthropod diversity and G. sessiliflorum and H. chathamica had the highest densities of these arthropods. Several plant species associated with higher soil moisture content than in control plots. The best performing species

  9. Leaf and life history traits predict plant growth in a green roof ecosystem.

    Science.gov (United States)

    Lundholm, Jeremy; Heim, Amy; Tran, Stephanie; Smith, Tyler

    2014-01-01

    Green roof ecosystems are constructed to provide services such as stormwater retention and urban temperature reductions. Green roofs with shallow growing media represent stressful conditions for plant survival, thus plants that survive and grow are important for maximizing economic and ecological benefits. While field trials are essential for selecting appropriate green roof plants, we wanted to determine whether plant leaf traits could predict changes in abundance (growth) to provide a more general framework for plant selection. We quantified leaf traits and derived life-history traits (Grime's C-S-R strategies) for 13 species used in a four-year green roof experiment involving five plant life forms. Changes in canopy density in monocultures and mixtures containing one to five life forms were determined and related to plant traits using multiple regression. We expected traits related to stress-tolerance would characterize the species that best grew in this relatively harsh setting. While all species survived to the end of the experiment, canopy species diversity in mixture treatments was usually much lower than originally planted. Most species grew slower in mixture compared to monoculture, suggesting that interspecific competition reduced canopy diversity. Species dominant in mixture treatments tended to be fast-growing ruderals and included both native and non-native species. Specific leaf area was a consistently strong predictor of final biomass and the change in abundance in both monoculture and mixture treatments. Some species in contrasting life-form groups showed compensatory dynamics, suggesting that life-form mixtures can maximize resilience of cover and biomass in the face of environmental fluctuations. This study confirms that plant traits can be used to predict growth performance in green roof ecosystems. While rapid canopy growth is desirable for green roofs, maintenance of species diversity may require engineering of conditions that favor less

  10. Leaf and life history traits predict plant growth in a green roof ecosystem.

    Directory of Open Access Journals (Sweden)

    Jeremy Lundholm

    Full Text Available Green roof ecosystems are constructed to provide services such as stormwater retention and urban temperature reductions. Green roofs with shallow growing media represent stressful conditions for plant survival, thus plants that survive and grow are important for maximizing economic and ecological benefits. While field trials are essential for selecting appropriate green roof plants, we wanted to determine whether plant leaf traits could predict changes in abundance (growth to provide a more general framework for plant selection. We quantified leaf traits and derived life-history traits (Grime's C-S-R strategies for 13 species used in a four-year green roof experiment involving five plant life forms. Changes in canopy density in monocultures and mixtures containing one to five life forms were determined and related to plant traits using multiple regression. We expected traits related to stress-tolerance would characterize the species that best grew in this relatively harsh setting. While all species survived to the end of the experiment, canopy species diversity in mixture treatments was usually much lower than originally planted. Most species grew slower in mixture compared to monoculture, suggesting that interspecific competition reduced canopy diversity. Species dominant in mixture treatments tended to be fast-growing ruderals and included both native and non-native species. Specific leaf area was a consistently strong predictor of final biomass and the change in abundance in both monoculture and mixture treatments. Some species in contrasting life-form groups showed compensatory dynamics, suggesting that life-form mixtures can maximize resilience of cover and biomass in the face of environmental fluctuations. This study confirms that plant traits can be used to predict growth performance in green roof ecosystems. While rapid canopy growth is desirable for green roofs, maintenance of species diversity may require engineering of conditions that

  11. Plant functional group composition modifies the effects of precipitation change on grassland ecosystem function.

    Science.gov (United States)

    Fry, Ellen L; Manning, Pete; Allen, David G P; Hurst, Alex; Everwand, Georg; Rimmler, Martin; Power, Sally A

    2013-01-01

    Temperate grassland ecosystems face a future of precipitation change, which can alter community composition and ecosystem functions through reduced soil moisture and waterlogging. There is evidence that functionally diverse plant communities contain a wider range of water use and resource capture strategies, resulting in greater resistance of ecosystem function to precipitation change. To investigate this interaction between composition and precipitation change we performed a field experiment for three years in successional grassland in southern England. This consisted of two treatments. The first, precipitation change, simulated end of century predictions, and consisted of a summer drought phase alongside winter rainfall addition. The second, functional group identity, divided the plant community into three groups based on their functional traits- broadly described as perennials, caespitose grasses and annuals- and removed these groups in a factorial design. Ecosystem functions related to C, N and water cycling were measured regularly. Effects of functional groupidentity were apparent, with the dominant trend being that process rates were higher under control conditions where a range of perennial species were present. E.g. litter decomposition rates were significantly higher in plots containing several perennial species, the group with the highest average leaf N content. Process rates were also very strongly affected by the precipitation change treatmentwhen perennial plant species were dominant, but not where the community contained a high abundance of annual species and caespitose grasses. This contrasting response could be attributable to differing rooting patterns (shallower structures under annual plants, and deeper roots under perennials) and faster nutrient uptake in annuals compared to perennials. Our results indicate that precipitation change will have a smaller effect on key process rates in grasslandscontaining a range of perennial and annual species

  12. Plant functional group composition modifies the effects of precipitation change on grassland ecosystem function.

    Directory of Open Access Journals (Sweden)

    Ellen L Fry

    Full Text Available Temperate grassland ecosystems face a future of precipitation change, which can alter community composition and ecosystem functions through reduced soil moisture and waterlogging. There is evidence that functionally diverse plant communities contain a wider range of water use and resource capture strategies, resulting in greater resistance of ecosystem function to precipitation change. To investigate this interaction between composition and precipitation change we performed a field experiment for three years in successional grassland in southern England. This consisted of two treatments. The first, precipitation change, simulated end of century predictions, and consisted of a summer drought phase alongside winter rainfall addition. The second, functional group identity, divided the plant community into three groups based on their functional traits- broadly described as perennials, caespitose grasses and annuals- and removed these groups in a factorial design. Ecosystem functions related to C, N and water cycling were measured regularly. Effects of functional groupidentity were apparent, with the dominant trend being that process rates were higher under control conditions where a range of perennial species were present. E.g. litter decomposition rates were significantly higher in plots containing several perennial species, the group with the highest average leaf N content. Process rates were also very strongly affected by the precipitation change treatmentwhen perennial plant species were dominant, but not where the community contained a high abundance of annual species and caespitose grasses. This contrasting response could be attributable to differing rooting patterns (shallower structures under annual plants, and deeper roots under perennials and faster nutrient uptake in annuals compared to perennials. Our results indicate that precipitation change will have a smaller effect on key process rates in grasslandscontaining a range of perennial

  13. The arable plant ecosystem as battleground for emergence of human pathogens

    Directory of Open Access Journals (Sweden)

    Leo eVan Overbeek

    2014-03-01

    Full Text Available Disease incidences related to Escherichia coli and Salmonella enterica infections by consumption of (fresh vegetables, sprouts and occasionally fruits made clear that these pathogens are not only transmitted to humans via the ‘classical’ routes of meat, eggs and dairy products, but also can be transmitted to humans via plants or products derived from plants. Nowadays, it is of major concern that these human pathogens, especially the ones belonging to the taxonomical family of Enterobacteriaceae, become adapted to environmental habitats without losing their virulence to humans. Adaptation to the plant environment would lead to longer persistence in plants, increasing their chances on transmission to humans via consumption of plant-derived food. One of the mechanisms of adaptation to the plant environment in human pathogens, proposed in this paper, is horizontal transfer of genes from different microbial communities present in the arable ecosystem, like the ones originating from soil, animal digestive track systems (manure, water and plants themselves. Genes that would confer better adaptation to the phytosphere might be genes involved in plant colonization, stress resistance and nutrient acquisition and utilization. Because human pathogenic enterics often were prone to genetic exchanges via phages and conjugative plasmids, it was postulated that these genetic elements may be hold key responsible for horizontal gene transfers between human pathogens and indigenous microbes in agroproduction systems. In analogy to zoonosis, we coin the term phytonosis for a human pathogen that is transmitted via plants and not exclusively via animals.

  14. Defensive plant-ants stabilize megaherbivore-driven landscape change in an African savanna.

    Science.gov (United States)

    Goheen, Jacob R; Palmer, Todd M

    2010-10-12

    Tree cover in savanna ecosystems is usually regarded as unstable, varying with rainfall, fire, and herbivory. In sub-Saharan Africa, elephants (Loxodonta africana) suppress tree cover, thereby maintaining landscape heterogeneity by promoting tree-grass coexistence. In the absence of elephants, tree encroachment may convert savannas into closed-canopy woodlands; when elephants increase in abundance, intensified browsing pressure can transform savannas into open grasslands. We show that symbiotic ants stabilize tree cover across landscapes in Kenya by protecting a dominant tree from elephants. In feeding trials, elephants avoided plants with ants and did not distinguish between a myrmecophyte (the whistling-thorn tree [Acacia drepanolobium]) from which ants had been removed and a highly palatable, nonmyrmecophytic congener. In field experiments, elephants inflicted severe damage on whistling-thorn trees from which ants had been removed. Across two properties on which elephants increased between 2003 and 2008, cover of whistling-thorn did not change significantly inside versus outside large-scale elephant exclusion fences; over the same period of time, cover of nonmyrmecophytes differed profoundly inside versus outside exclusion fences. These results highlight the powerful role that symbioses and plant defense play in driving tree growth and survival in savannas, ecosystems of global economic and ecological importance.

  15. Analysis of the production stability of mixed grasslands. II. A mathematical framework for the quantification of production stability of grassland ecosystems

    NARCIS (Netherlands)

    Schulte, R.P.O.

    2003-01-01

    The analysis of the intrinsic properties and processes of ecosystems, which regulate the production stability of mixed grasslands, has been complicated by the environmental noise caused by stochastic weather fluctuations. A mathematical framework is presented to deduct the actual, the extrinsic and

  16. Declining plant nitrogen supply and carbon accumulation in ageing primary boreal forest ecosystems

    Science.gov (United States)

    Högberg, Mona N.; Yarwood, Stephanie A.; Trumbore, Susan; Högberg, Peter

    2016-04-01

    Boreal forest soils are commonly characterized by a low plant nitrogen (N) supply. A high tree below-ground allocation of carbon (C) to roots and soil microorganisms in response to the shortage of N may lead to high microbial immobilisation of N, thus aggravating the N limitation. We studied the N supply at a Swedish boreal forest ecosystem chronosequence created by new land rising out of the sea due to iso-static rebound. The youngest soils develop with meadows by the coast, followed by a zone of dinitrogen fixing alder trees, and primary boreal conifer forest on ground up to 560 years old. With increasing ecosystem age, the proportion of microbial C out of the total soil C pool from the youngest to the oldest coniferous ecosystem was constant (c. 1-1.5%), whereas immobilised N (microbial N out of total soil N) increased and approached the levels commonly observed in similar boreal coniferous forests (c. 6-7 %), whereas gross N mineralization declined. Simultaneously, plant foliar N % decreased and the natural abundance of N-15 in the soil increased. More specifically, the difference in N-15 between plant foliage and soil increased, which is related to greater retention of N-15 relative to N-14 by ectomycorrhizal fungi as N is taken up from the soil and some N is transferred to the plant host. In the conifer forest, where these changes were greatest, we found increased fungal biomass in the F- and H-horizons of the mor-layer, in which ectomycorrhizal fungi are known to dominate (the uppermost horizon with litter and moss is dominated by saprotrophic fungi). Hence, we propose that the decreasing N supply to the plants and the subsequent decline in plant production in ageing boreal forests is linked to high tree belowground C allocation to C limited ectomycorrhizal fungi (and other soil microorganisms), a strong sink for available soil N. Data on organic matter C-14 suggested that the largest input of recently fixed plant C occurred in the younger coniferous forest

  17. Restoration and management for plant diversity enhances the rate of belowground ecosystem recovery.

    Science.gov (United States)

    Klopf, Ryan P; Baer, Sara G; Bach, Elizabeth M; Six, Johan

    2017-03-01

    The positive relationship between plant diversity and ecosystem functioning has been criticized for its applicability at large scales and in less controlled environments that are relevant to land management. To inform this gap between ecological theory and application, we compared recovery rates of belowground properties using two chronosequences consisting of continuously cultivated and independently restored fields with contrasting diversity management strategies: grasslands restored with high plant richness and managed for diversity with frequent burning (n = 20) and grasslands restored with fewer species that were infrequently burned (n = 15). Restoration and management for plant diversity resulted in 250% higher plant richness. Greater recovery of roots and more predictable recovery of the active microbial biomass across the high diversity management strategy chronosequence corresponded with faster recovery of soil structure. The high diversity grasslands also had greater nutrient conservation indicated by lower available inorganic nitrogen. Thus, mesic grasslands restored with more species and managed for high plant diversity with frequent burning enhances the rate of belowground ecosystem recovery from long-term disturbance at a scale relevant to conservation practices on the landscape.

  18. Building relationships between plant traits and leaf spectra to reduce uncertainty in terrestrial ecosystem models

    Science.gov (United States)

    Lieberman-Cribbin, W.; Rogers, A.; Serbin, S.; Ely, K.

    2015-12-01

    Despite climate projections, there is uncertainty in how terrestrial ecosystems will respond to warming temperatures and increased atmospheric carbon dioxide concentrations. Earth system models are used to determine how ecosystems will respond in the future, but there is considerable variation in how plant traits are represented within these models. A potential approach to reducing uncertainty is the establishment of spectra-trait linkages among plant species. These relationships allow the accurate estimation of biochemical characteristics of plants from their shortwave spectral profiles. Remote sensing approaches can then be implemented to acquire spectral data and estimate plant traits over large spatial and temporal scales. This paper describes a greenhouse experiment conducted at Brookhaven National Laboratory in which spectra-trait relationships were investigated for 8 different plant species. This research was designed to generate a broad gradient in plant traits, using a range of species grown in different sized pots with different soil type. Fertilizer was also applied in different amounts to generate variation in plant C and N status that will be reflected in the traits measured, as well as the spectra observed. Leaves were sampled at different developmental stages to increase variation. Spectra and plant traits were then measured and a partial least-squares regression (PLSR) modeling approach was used to establish spectra-trait relationships. Despite the variability in growing conditions and plant species, our PLSR models could be used to accurately estimate plant traits from spectral signatures, yielding model calibration R2 and root mean square error (RMSE) values, respectively, of 0.85 and 0.30 for percent nitrogen by mass (Nmass%), R2 0.78 and 0.75 for carbon to nitrogen (C:N) ratio, 0.87 and 2.39 for leaf mass area (LMA), and 0.76 R2 and 15.16 for water (H2O) content. This research forms the basis for establishing new and more comprehensive spectra

  19. Heavy metal pollution in aquatic ecosystems and its phytoremediation using wetland plants: an ecosustainable approach.

    Science.gov (United States)

    Rai, Prabhat Kumar

    2008-01-01

    This review addresses the global problem of heavymetal pollution originating from increased industrialization and urbanization and its amelioration by using wetland plants both in a microcosm as well as natural/field condition. Heavymetal contamination in aquatic ecosystems due to discharge of industrial effluents may pose a serious threat to human health. Alkaline precipitation, ion exchange columns, electrochemical removal, filtration, and membrane technologies are the currently available technologies for heavy metal removal. These conventional technologies are not economical and may produce adverse impacts on aquatic ecosystems. Phytoremediation of metals is a cost-effective "green" technology based on the use of specially selected metal-accumulating plants to remove toxic metals from soils and water. Wetland plants are important tools for heavy metal removal. The Ramsar convention, one of the earlier modern global conservation treaties, was adopted at Ramsar, Iran, in 1971 and became effective in 1975. This convention emphasized the wise use of wetlands and their resources. This review mentions salient features of wetland ecosystems, their vegetation component, and the pros and cons involved in heavy metal removal. Wetland plants are preferred over other bio-agents due to their low cost, frequent abundance in aquatic ecosystems, and easy handling. The extensive rhizosphere of wetland plants provides an enriched culture zone for the microbes involved in degradation. The wetland sediment zone provides reducing conditions that are conducive to the metal removal pathway. Constructed wetlands proved to be effective for the abatement of heavymetal pollution from acid mine drainage; landfill leachate; thermal power; and municipal, agricultural, refinery, and chlor-alkali effluent. the physicochemical properties of wetlands provide many positive attributes for remediating heavy metals. Typha, Phragmites, Eichhornia, Azolla, Lemna, and other aquatic macrophytes are some

  20. Soil and plant changing after invasion: the case of Acacia dealbata in a Mediterranean ecosystem.

    Science.gov (United States)

    Lazzaro, Lorenzo; Giuliani, Claudia; Fabiani, Arturo; Agnelli, Alessandro Elio; Pastorelli, Roberta; Lagomarsino, Alessandra; Benesperi, Renato; Calamassi, Roberto; Foggi, Bruno

    2014-11-01

    Acacia dealbata Link (Fabaceae) is one of the most invasive species in the Mediterranean ecosystems of Europe, Africa and America, where it has been proved to exert strong effects on soil and plant communities. In Italy A. dealbata has been largely used for ornamental and forestry purpose and is nowadays spreading in several areas. The present study was addressed to evaluate the impacts on soil chemical properties, soil microbial communities and understory plant communities and to assess the relationships among these compartments after the invasion of A. dealbata in a typical Mediterranean shrubland. Towards these aims, a soil and vegetation sampling was performed in Elba Island where A. dealbata is invading the sclerophyllous native vegetation. Three levels of invasion status were differentiated according to the gradient from invaded, to transitional and non-invaded vegetation. Quantitative and qualitative alterations of soil chemical properties and microbial communities (i.e. bacterial and fungal communities) and above-ground understory plant communities were found. In particular, the invaded soils had lower pH values than both the non-invaded and transitional ones. High differences were detected for both the total N and the inorganic fraction (NH4(+) and NO3(-)) contents, which showed the ranking: invaded>transitional>non-invaded soils. TOC and C/N ratio showed respectively higher and lower values in invaded than in non-invaded soils. Total plant covers, species richness and diversity in both the non-invaded and transitional subplots were higher than those in the invaded ones. The contribution of the nitrophilous species was significantly different among the three invasion statuses, with a strong increase going from native to transitional and invaded subplots. All these data confirm that A. dealbata modifies several compartments of the invaded ecosystems, from soil chemical properties to soil and plant microbial communities determining strong changes in the

  1. Rapid demise and recovery of plant ecosystems across the end-Permian extinction event

    Science.gov (United States)

    Hochuli, Peter A.; Hermann, Elke; Vigran, Jorunn Os; Bucher, Hugo; Weissert, Helmut

    2010-12-01

    The end-Permian extinction event was the most pronounced biotic and ecological crisis in the history of the Earth. It is assumed that over 80% of marine genera disappeared, and that this event had a major impact on the evolution of marine organisms. The impact of this event on terrestrial biota is poorly known and a matter of controversial discussions. In contrast to the fundamental changes in marine fauna most major groups of plants range from the Late Palaeozoic into the Mesozoic. Consequently the impact of the end-Permian extinction event on the evolution of plants was often regarded as minor. However, major changes in the composition of the plant communities have been documented and a number of catastrophic scenarios have been envisioned — including the almost total destruction of plant ecosystems. Based on expanded sections from the Southern Barents Sea (Northern Norway) we trace mid-latitudinal terrestrial ecosystems across the Permo-Triassic transition with a time resolution in the order of 10 kyr, based on a high resolution C org-isotope stratigraphy. Our results show that the floral turnovers are linked with major changes in the C-isotope record and hence with global carbon cycling. The palynological records document the successive steps in the evolution of terrestrial ecosystems. After gradual changes during the latest Permian, plant ecosystems suffered from a major environmental perturbation leading to a rapid turnover from gymnosperm dominated ecosystems to assemblages dominated by lycopods. The dominance of the lycopods, expressed in a spore-spike, represents a relatively short-lived event in the order of 10 kyr. This perturbation of the terrestrial ecosystems preceded the globally recognized negative δ 13C org isotope spike by up to 100 kyr. It coincides with a first end-Permian negative shift of the C-isotope curve and was probably induced by a first major perturbation of the chemistry of the atmosphere, related to the onset of the volcanic

  2. Ecosystem consequences of enhanced solar ultraviolet radiation: secondary plant metabolites as mediators of multiple trophic interactions in terrestrial plant communities.

    Science.gov (United States)

    Bassman, John H

    2004-05-01

    The potential role of ultraviolet-B (UV-B)-induced secondary plant metabolites as mediators of multiple trophic responses in terrestrial ecosystems is considered through review of the major classes of secondary metabolites, the pathways for their biosynthesis, interactions with primary and secondary consumers and known UV effects on their induction. Gross effects of UV-B radiation on plant growth and survival under realistic spectral balances in the field have been generally lacking, but subtle changes in carbon allocation and partitioning induced by UV-B, in particular production of secondary metabolites, can affect ecosystem-level processes. Secondary metabolites are important in plant-herbivore interactions and may affect pathogens. They act as feeding or oviposition deterrents to generalists and nonadapted specialists, but adapted specialists are stimulated to feed by these same compounds, which they detoxify and often sequester for use against their predators. This provides a route for tritrophic effects of enhanced UV-B radiation whereby herbivory may be increased while predation on the herbivore is simultaneously reduced. It is in this context that secondary metabolites may manifest their most important role. They can be the demonstrable mechanism establishing cause and effect at higher trophic levels because the consequences of their induction can be established at all trophic levels.

  3. Woody-plant ecosystems under climate change and air pollution-response consistencies across zonobiomes?

    Science.gov (United States)

    Matyssek, R; Kozovits, A R; Wieser, G; King, J; Rennenberg, H

    2017-06-01

    Forests store the largest terrestrial pools of carbon (C), helping to stabilize the global climate system, yet are threatened by climate change (CC) and associated air pollution (AP, highlighting ozone (O3) and nitrogen oxides (NOx)). We adopt the perspective that CC-AP drivers and physiological impacts are universal, resulting in consistent stress responses of forest ecosystems across zonobiomes. Evidence supporting this viewpoint is presented from the literature on ecosystem gross/net primary productivity and water cycling. Responses to CC-AP are compared across evergreen/deciduous foliage types, discussing implications of nutrition and resource turnover at tree and ecosystem scales. The availability of data is extremely uneven across zonobiomes, yet unifying patterns of ecosystem response are discernable. Ecosystem warming results in trade-offs between respiration and biomass production, affecting high elevation forests more than in the lowland tropics and low-elevation temperate zone. Resilience to drought is modulated by tree size and species richness. Elevated O3 tends to counteract stimulation by elevated carbon dioxide (CO2). Biotic stress and genomic structure ultimately determine ecosystem responsiveness. Aggrading early- rather than mature late-successional communities respond to CO2 enhancement, whereas O3 affects North American and Eurasian tree species consistently under free-air fumigation. Insect herbivory is exacerbated by CC-AP in biome-specific ways. Rhizosphere responses reflect similar stand-level nutritional dynamics across zonobiomes, but are modulated by differences in tree-soil nutrient cycling between deciduous and evergreen systems, and natural versus anthropogenic nitrogen (N) oversupply. The hypothesis of consistency of forest responses to interacting CC-AP is supported by currently available data, establishing the precedent for a global network of long-term coordinated research sites across zonobiomes to simultaneously advance both

  4. Modelling the Influence of Ectomycorrhizal Decomposition on Plant Nutrition and Carbon Sequestartion in Boreal Forst Ecosystem

    Science.gov (United States)

    Baskaran, P.; Hyvönen, R.; Agren, G. I.; Clemmensen, K.; Lindahl, B.; Manzoni, S.

    2016-12-01

    Tree growth in boreal forests is limited by nitrogen availability (N). Most boreal forest trees form symbiotic association with ectomycorrhizal (ECM) fungi, that improve uptake of inorganic N and also have the capacity to decompose soil organic matter and to mobilize organic N (`ECM decomposition'). To mechanistically understand the effect of `ECM decomposition' on ecosystem C and N balances, we formulated a model of C and N flows to and from plants, SOM, saprotrophs, ECM fungi, and inorganic N stores. Our predictions indicate that the optimal C allocation to ECM fungi, above which the symbiosis switches from mutualism to parasitism, depends strongly on the partitioning of soil organic matter decomposition between ECM fungi and saprotrophs. At high relative ECM decomposition and low N availability, optimal C allocation was estimated to 15% of NPP. The model also predicts a negative correlation between plant production and soil C sequestration, as increased plant belowground C allocation increases ECM mining of organic N which promotes tree growth but decreases soil C storage. In conclusion, our model provides a tool for studying ecosystem productivity and C storage, where ECM decomposition acts as a potential driver of both decomposition of soil organic matter and plant N uptake.

  5. Irrigation and Maize Cultivation Erode Plant Diversity Within Crops in Mediterranean Dry Cereal Agro-Ecosystems.

    Science.gov (United States)

    Fagúndez, Jaime; Olea, Pedro P; Tejedo, Pablo; Mateo-Tomás, Patricia; Gómez, David

    2016-07-01

    The intensification of agriculture has increased production at the cost of environment and biodiversity worldwide. To increase crop yield in dry cereal systems, vast farmland areas of high conservation value are being converted into irrigation, especially in Mediterranean countries. We analyze the effect of irrigation-driven changes on the farm biota by comparing species diversity, community composition, and species traits of arable plants within crop fields from two contrasting farming systems (dry and irrigated) in Spain. We sampled plant species within 80 fields of dry wheat, irrigated wheat, and maize (only cultivated under irrigation). Wheat crops held higher landscape and per field species richness, and beta diversity than maize. Within the same type of crop, irrigated wheat hosted lower plant diversity than dry wheat at both field and landscape scales. Floristic composition differed between crop types, with higher frequencies of perennials, cosmopolitan, exotic, wind-pollinated and C4 species in maize. Our results suggest that irrigation projects, that transform large areas of dry cereal agro-ecosystems into irrigated crop systems dominated by maize, erode plant diversity. An adequate planning on the type and proportion of crops used in the irrigated agro-ecosystems is needed in order to balance agriculture production and biodiversity conservation.

  6. Heavy metal pollution in aquatic ecosystems and its phytoremediation using wetland plants: An ecosustainable approach

    Energy Technology Data Exchange (ETDEWEB)

    Rai, P.K. [Mizoram Central University, Tanhril (India). School for Earth Science & Natural Resource Management

    2008-07-01

    This review addresses the global problem of heavy metal pollution originating from increased industrialization and urbanization and its amelioration by using wetland plants both in a microcosm as well as natural/field condition. This review mentions salient features of wetland ecosystems, their vegetation component, and the pros and cons involved in heavy metal removal. Wetland plants are preferred over other bio-agents due to their low cost, frequent abundance in aquatic ecosystems, and easy handling. Constructed wetlands proved to be effective for the abatement of heavy metal pollution from acid mine drainage; landfill leachate; thermal power; and municipal, agricultural, refinery, and chlor-alkali effluent. the physicochemical properties of wetlands provide many positive attributes for remediating heavy metals. Typha, Phragmites, Eichhornia, Azolla, Lemna, and other aquatic macrophytes are some of the potent wetland plants for heavy metal removal. Biomass disposal problem and seasonal growth of aquatic macrophytes are some limitations in the transfer of phytoremediation technology from the laboratory to the field. However, the disposed biomass of macrophytes may be used for various fruitful applications. An ecosustainable model has been developed through the author's various works, which may ameliorate some of the limitations. The creation of more areas for phytoremediation may also aid in wetlands conservation. Genetic engineering and biodiversity prospecting of endangered wetland plants are important future prospects in this regard.

  7. Irrigation and Maize Cultivation Erode Plant Diversity Within Crops in Mediterranean Dry Cereal Agro-Ecosystems

    Science.gov (United States)

    Fagúndez, Jaime; Olea, Pedro P.; Tejedo, Pablo; Mateo-Tomás, Patricia; Gómez, David

    2016-07-01

    The intensification of agriculture has increased production at the cost of environment and biodiversity worldwide. To increase crop yield in dry cereal systems, vast farmland areas of high conservation value are being converted into irrigation, especially in Mediterranean countries. We analyze the effect of irrigation-driven changes on the farm biota by comparing species diversity, community composition, and species traits of arable plants within crop fields from two contrasting farming systems (dry and irrigated) in Spain. We sampled plant species within 80 fields of dry wheat, irrigated wheat, and maize (only cultivated under irrigation). Wheat crops held higher landscape and per field species richness, and beta diversity than maize. Within the same type of crop, irrigated wheat hosted lower plant diversity than dry wheat at both field and landscape scales. Floristic composition differed between crop types, with higher frequencies of perennials, cosmopolitan, exotic, wind-pollinated and C4 species in maize. Our results suggest that irrigation projects, that transform large areas of dry cereal agro-ecosystems into irrigated crop systems dominated by maize, erode plant diversity. An adequate planning on the type and proportion of crops used in the irrigated agro-ecosystems is needed in order to balance agriculture production and biodiversity conservation.

  8. Transfer parameters for ICRP's Reference Animals and Plants in a terrestrial Mediterranean ecosystem.

    Science.gov (United States)

    Guillén, J; Beresford, N A; Baeza, A; Izquierdo, M; Wood, M D; Salas, A; Muñoz-Serrano, A; Corrales-Vázquez, J M; Muñoz-Muñoz, J G

    2017-09-14

    A system for the radiological protection of the environment (or wildlife) based on Reference Animals and Plants (RAPs) has been suggested by the International Commission on Radiological Protection (ICRP). To assess whole-body activity concentrations for RAPs and the resultant internal dose rates, transfer parameters are required. However, transfer values specifically for the taxonomic families defined for the RAPs are often sparse and furthermore can be extremely site dependent. There is also a considerable geographical bias within available transfer data, with few data for Mediterranean ecosystems. In the present work, stable element concentrations (I, Li, Be, B, Na, Mg, Al, P, S, K. Ca, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, As, Se, Rb, Sr, Mo, Ag, Cd, Cs, Ba, Tl, Pb and U) in terrestrial RAPs, and the corresponding whole-body concentration ratios, CRwo, were determined in two different Mediterranean ecosystems: a Pinewood and a Dehesa (grassland with disperse tree cover). The RAPs considered in the Pinewood ecosystem were Pine Tree and Wild Grass; whereas in the Dehesa ecosystem those considered were Deer, Rat, Earthworm, Bee, Frog, Duck and Wild Grass. The CRwo values estimated from these data are compared to those reported in international compilations and databases. Copyright © 2017. Published by Elsevier Ltd.

  9. Regulating plant/insect interactions using CO2 enrichment in model ecosystems

    Science.gov (United States)

    Grodzinski, B.; Schmidt, J. M.; Watts, B.; Taylor, J.; Bates, S.; Dixon, M. A.; Staines, H.

    1999-01-01

    The greenhouse environment is a challenging artificial ecosystem in which it is possible to study selected plant/insect interaction in a controlled environment. Due to a combination of ``direct'' and ``indirect'' effects of CO2 enrichment on plant photosynthesis and plant development, canopy productivity is generally increased. In this paper, we discuss the effects of daytime and nighttime CO2 enrichment protocols on gas exchange of pepper plants (Capsicum annuum L, cv Cubico) grown in controlled environments. In addition, we present the effects of thrips, a common insect pest, on the photosynthetic and respiratory activity of these plant canopies. Carbon dioxide has diverse effects on the physiology and mortality of insects. However, our data indicate that thrips and whiteflies, at least, are not killed ``directly'' by CO2 levels used to enhance photosynthesis and plant growth. Together the data suggest that the insect population is affected ``indirectly'' by CO2 and that the primary effect of CO2 is via its effects on plant metabolism.

  10. Links between plant litter chemistry, species diversity, and below-ground ecosystem function.

    Science.gov (United States)

    Meier, Courtney L; Bowman, William D

    2008-12-16

    Decomposition is a critical source of plant nutrients, and drives the largest flux of terrestrial C to the atmosphere. Decomposing soil organic matter typically contains litter from multiple plant species, yet we lack a mechanistic understanding of how species diversity influences decomposition processes. Here, we show that soil C and N cycling during decomposition are controlled by the composition and diversity of chemical compounds within plant litter mixtures, rather than by simple metrics of plant species diversity. We amended native soils with litter mixtures containing up to 4 alpine plant species, and we used 9 litter chemical traits to evaluate the chemical composition (i.e., the identity and quantity of compounds) and chemical diversity of the litter mixtures. The chemical composition of the litter mixtures was the strongest predictor of soil respiration, net N mineralization, and microbial biomass N. Soil respiration and net N mineralization rates were also significantly correlated with the chemical diversity of the litter mixtures. In contrast, soil C and N cycling rates were poorly correlated with plant species richness, and there was no relationship between species richness and the chemical diversity of the litter mixtures. These results indicate that the composition and diversity of chemical compounds in litter are potentially important functional traits affecting decomposition, and simple metrics like plant species richness may fail to capture variation in these traits. Litter chemical traits therefore provide a mechanistic link between organisms, species diversity, and key components of below-ground ecosystem function.

  11. Resource dependence in a new ecosystem: A host plant and its colonizing community

    Science.gov (United States)

    Lakatos, K. Tímea; László, Zoltán; Tóthmérész, Béla

    2016-05-01

    The introduced black locust (Robinia pseudoacacia) has become an invasive plant species in Europe. The introduction of alien plants such as the black locust may modify ecosystem composition and functioning. In response to the presence of a potential host plant, herbivores can adapt and shift to the consumption of the new host plant. In Eastern-Central Europe, the seed predator Bruchophagus robiniae (Hymenoptera: Eurytomidae) is an important consumer of black locust seeds which presumably shifted from its formerly host species to black locust. We tested the influence of host plant abundance on a seed predator - parasitoid community. We found that the seed predator B. robiniae was present in higher numbers in woodlots than in small patches of black locust. The density of the specialist parasitoid Mesopolobus sp. was lower in woodlots than in small patches, while the generalist parasitoid Eupelmus urozonos was evenly distributed between woodlots and small patches of black locust. We found that parasitoid species are influenced by the patch size of host plants, thus characteristics of introduced host plants can also manifest in higher trophic levels.

  12. Isolation and enzyme bioprospection of endophytic bacteria associated with plants of Brazilian mangrove ecosystem.

    Science.gov (United States)

    Castro, Renata A; Quecine, Maria Carolina; Lacava, Paulo T; Batista, Bruna D; Luvizotto, Danice M; Marcon, Joelma; Ferreira, Anderson; Melo, Itamar S; Azevedo, João L

    2014-01-01

    The mangrove ecosystem is a coastal tropical biome located in the transition zone between land and sea that is characterized by periodic flooding, which confers unique and specific environmental conditions on this biome. In these ecosystems, the vegetation is dominated by a particular group of plant species that provide a unique environment harboring diverse groups of microorganisms, including the endophytic microorganisms that are the focus of this study. Because of their intimate association with plants, endophytic microorganisms could be explored for biotechnologically significant products, such as enzymes, proteins, antibiotics and others. Here, we isolated endophytic microorganisms from two mangrove species, Rhizophora mangle and Avicennia nitida, that are found in streams in two mangrove systems in Bertioga and Cananéia, Brazil. Bacillus was the most frequently isolated genus, comprising 42% of the species isolated from Cananéia and 28% of the species from Bertioga. However, other common endophytic genera such as Pantoea, Curtobacterium and Enterobacter were also found. After identifying the isolates, the bacterial communities were evaluated for enzyme production. Protease activity was observed in 75% of the isolates, while endoglucanase activity occurred in 62% of the isolates. Bacillus showed the highest activity rates for amylase and esterase and endoglucanase. To our knowledge, this is the first reported diversity analysis performed on endophytic bacteria obtained from the branches of mangrove trees and the first overview of the specific enzymes produced by different bacterial genera. This work contributes to our knowledge of the microorganisms and enzymes present in mangrove ecosystems.

  13. Belowground plant biomass allocation in tundra ecosystems and its relationship with temperature

    Science.gov (United States)

    Wang, Peng; Heijmans, Monique M. P. D.; Mommer, Liesje; van Ruijven, Jasper; Maximov, Trofim C.; Berendse, Frank

    2016-05-01

    Climate warming is known to increase the aboveground productivity of tundra ecosystems. Recently, belowground biomass is receiving more attention, but the effects of climate warming on belowground productivity remain unclear. Enhanced understanding of the belowground component of the tundra is important in the context of climate warming, since most carbon is sequestered belowground in these ecosystems. In this study we synthesized published tundra belowground biomass data from 36 field studies spanning a mean annual temperature (MAT) gradient from -20 °C to 0 °C across the tundra biome, and determined the relationships between different plant biomass pools and MAT. Our results show that the plant community biomass-temperature relationships are significantly different between above and belowground. Aboveground biomass clearly increased with MAT, whereas total belowground biomass and fine root biomass did not show a significant increase over the broad MAT gradient. Our results suggest that biomass allocation of tundra vegetation shifts towards aboveground in warmer conditions, which could impact on the carbon cycling in tundra ecosystems through altered litter input and distribution in the soil, as well as possible changes in root turnover.

  14. Application of nanoelements in plant nutrition and its impact in ecosystems

    Science.gov (United States)

    Berenice Morales-Díaz, América; Ortega-Ortíz, Hortensia; Juárez-Maldonado, Antonio; Cadenas-Pliego, Gregorio; González-Morales, Susana; Benavides-Mendoza, Adalberto

    2017-03-01

    Agriculture stands to benefit from nanotechnology in areas such as combating pests and pathogens, regulating the growth and quality of crops, and developing intelligent materials and nanosensors. The objective of this paper is to provide an overview of the use of nanomaterials (NMs) and nanoparticles (NPs) in plant nutrition, highlighting their advantages and potential uses, but also reviewing their possible environmental destination and effects on ecosystems and consumers. NPs and NMs have been shown to be an attractive alternative for the manufacture of nanofertilizers (NFs), which are more effective and efficient than traditional fertilizers. Because of their impact on crop nutritional quality and stress tolerance in plants, the application of NFs is increasing. However, there are virtually no studies on the potential environmental impact of NPs and NMs when used in agriculture. These studies are necessary because NPs and NMs can be transferred to ecosystems by various pathways where they can cause toxicity to organisms, affecting the biodiversity and abundance of these ecosystems, and may ultimately even be transferred to consumers.

  15. Stakeholder Perceptions of an Ecosystem Services Approach to Clearing Invasive Alien Plants on Private Land

    Directory of Open Access Journals (Sweden)

    Lauren S. Urgenson

    2013-03-01

    Full Text Available Incentivizing private landowners and other stakeholders is central to the effective conservation of ecosystem services in working landscapes. To better understand how to design effective incentives, the perceptions of landowners and other stakeholders are explored regarding a proposed approach to clearing invasive alien plants on private land in the Western Cape Province, South Africa. The public funded national program, Working for Water, conserves ecosystem services while employing and training people from marginalized sectors of society to clear these plants. Private landowner involvement is a key conservation challenge, because without adequate landowner involvement, invasive alien plants persist on the landscape and continuously reinvade cleared areas. We collected interview data from private landowners in three study sites, and web-survey data from conservation professionals and Working for Water managers, in order to compare stakeholder perceptions of (1 government and landowners' responsibilities for clearing invasive alien plants; (2 existing and proposed policy tools; and (3 the extent to which stakeholders consider the proposed financial incentive to be sufficient. There was significant consensus among stakeholders concerning their preference for shared landowner and government responsibility and for a policy mix that combines incentives with disincentives. Landowners from the three study sites differed in the level of responsibility they were willing to assume. Stakeholders also diverged in terms of their perceptions of the proposed financial incentives. Furthermore, the perspectives of landowners were strongly associated with ecological and social features of the landscapes in which they are located. Understanding stakeholders' points of view within their differing contexts is shown to be a valuable means of gaining insight into the opportunities and constraints that face ecosystem service conservation in working landscapes.

  16. Plant hydraulic controls over ecosystem responses to climate-enhanced disturbances

    Science.gov (United States)

    Mackay, D. S.; Ewers, B. E.; Reed, D. E.; Pendall, E.; McDowell, N. G.

    2012-12-01

    Climate-enhanced disturbances such as drought and insect infestation range in severity, contributing minor to severe stress to forests including forest mortality. While neither form of disturbance has been unambiguously implicated as a mechanism of mortality, both induce changes in water, carbon, and nutrient cycling that are key to understanding forest ecosystem response to, and recovery from, disturbance. Each disturbance type has different biophysical, ecohydrological, and biogeochemical signatures that potentially complicate interpretation and development of theory. Plant hydraulic function is arguably a unifying control over these responses to disturbance because it regulates stomatal conductance, leaf biochemistry, carbon (C) uptake and utilization, and nutrient cycling. We demonstrated this idea by focusing on water and C, including non-structural (NSC), resources, and nitrogen (N) uptake across a spectrum of forest ecosystems (e.g., northern temperate mixed forests, lodgepole pine forests in the Rocky Mountains, and pinon pine - juniper woodlands in New Mexico) using the Terrestrial Regional Ecosystem Exchange Simulator (TREES). TREES is grounded in the biophysics of water movement through soil and plants, respectively via hydraulic conductivity of the soil and cavitation of xylem. It combines this dynamic plant hydraulic conductance with canopy biochemical controls over photosynthesis, and the dynamics of structural and non-structural carbon through a carbon budget that responds to plant hydraulic status. As such, the model can be used to develop testable hypotheses on a multitude of disturbance and recovery responses including xylem dysfunction, stomatal and non-stomatal controls on photosynthesis and carbon allocation, respiration, and allocation to defense compounds. For each of the ecosystems we constrained and evaluated the model with allometry, sap flux and/or eddy covariance data, leaf gas exchange measurements, and vulnerability to cavitation data

  17. Effects of soil-plant system change on ecohydrology during revegetation for mobile dune stabilization, Chinese arid desert

    Institute of Scientific and Technical Information of China (English)

    2009-01-01

    Soil-plant systems play an important role in sand fixing and surface protection in the arid desert of China. This study examines the ecohydrological responses after a soil-plant system change for mobile dune stabilization by using a series of soil hydrological experiments and ecological investigation. The study results showed that decades of succession of soil-plant system has endangered the stability of the protection system. With the accumulated water and nutrient, a bio-logical system develops in a thinner and thinner surface soil. Redistribution of precipitation has changed completely in the ecosystem. In 3-15 mm of soil, a high capacity of crust water retention ultimately limits most rainfall from infiltrating below 10-20 cm deep. When that takes place, lower plants begin to compete for water with grasses and shrubs. A drought horizon forms in 20-500 cm depth with shrub transpiration. Artificial shrubs with deep roots obtain hardly rainfall supply and are gradually eliminated from the protection system. All changes in water environment affect the structure and func-tion and stabilization of whole protection systems. It is necessary to establish a relatively stable water environment by managing the soil-plant system for constructing a sustainable protective system in arid desert.

  18. Net ecosystem production in a Little Ice Age moraine: the role of plant functional traits

    Science.gov (United States)

    Varolo, E.; Zanotelli, D.; Tagliavini, M.; Zerbe, S.; Montagnani, L.

    2015-07-01

    Current glacier retreat allows vast mountain ranges available for vegetation establishment and growth. Little is known about the effective carbon (C) budget of these new ecosystems and how the presence of different vegetation communities, characterized by their specific physiology and life forms influences C fluxes. In this study, using a comparative analysis of the C fluxes of two contrasting vegetation types, we intend to evaluate if the different physiologies of the main species have an effect on Ecosystem Respiration (Reco), Gross Primary Production (GPP), annual cumulated Net Ecosystem Exchange (NEE), and long-term carbon accumulation in soil. The NEE of two plant communities present on a Little Ice Age moraine in the Matsch glacier forefield (Alps, Italy) was measured over two growing seasons. They are a typical C3 grassland, dominated by Festuca halleri All. and a community dominated by CAM rosettes Sempervivum montanum L. on rocky soils. Using transparent and opaque chambers, we extrapolated the ecophysiological responses to the main environmental drivers and performed the partition of NEE into Reco and GPP. Soil samples were collected from the same site to measure long-term C accumulation in the ecosystem. The two communities showed contrasting GPP but similar Reco patterns and as a result significantly different in NEE. The grassland acted mainly as a carbon sink with a total cumulated value of -46.4 ± 35.5 g C m-2 NEE while the plots dominated by the CAM rosettes acted as a source with 31.9 ± 22.4 g C m-2. In spite of the NEE being different in the two plant communities, soil analysis did not reveal significant differences in carbon accumulation. Grasslands showed 1.76 ± 0.12 kg C m-2, while CAM rosettes showed 2.06 ± 0.23 kg C m-2. This study demonstrates that carbon dynamics of two vegetation communities can be distinct even though the growing environment is similar. The physiological traits of the dominant species determine large differences in

  19. Net ecosystem production in a Little Ice Age moraine: the role of plant functional traits

    Directory of Open Access Journals (Sweden)

    E. Varolo

    2015-07-01

    Full Text Available Current glacier retreat allows vast mountain ranges available for vegetation establishment and growth. Little is known about the effective carbon (C budget of these new ecosystems and how the presence of different vegetation communities, characterized by their specific physiology and life forms influences C fluxes. In this study, using a comparative analysis of the C fluxes of two contrasting vegetation types, we intend to evaluate if the different physiologies of the main species have an effect on Ecosystem Respiration (Reco, Gross Primary Production (GPP, annual cumulated Net Ecosystem Exchange (NEE, and long-term carbon accumulation in soil. The NEE of two plant communities present on a Little Ice Age moraine in the Matsch glacier forefield (Alps, Italy was measured over two growing seasons. They are a typical C3 grassland, dominated by Festuca halleri All. and a community dominated by CAM rosettes Sempervivum montanum L. on rocky soils. Using transparent and opaque chambers, we extrapolated the ecophysiological responses to the main environmental drivers and performed the partition of NEE into Reco and GPP. Soil samples were collected from the same site to measure long-term C accumulation in the ecosystem. The two communities showed contrasting GPP but similar Reco patterns and as a result significantly different in NEE. The grassland acted mainly as a carbon sink with a total cumulated value of −46.4 ± 35.5 g C m−2 NEE while the plots dominated by the CAM rosettes acted as a source with 31.9 ± 22.4 g C m−2. In spite of the NEE being different in the two plant communities, soil analysis did not reveal significant differences in carbon accumulation. Grasslands showed 1.76 ± 0.12 kg C m−2, while CAM rosettes showed 2.06 ± 0.23 kg C m−2. This study demonstrates that carbon dynamics of two vegetation communities can be distinct even though the growing environment is similar. The physiological traits of the dominant species

  20. Relationship and its ecological significance between plant species diversity and ecosystem function of soil conservation in semi-humid evergreen forests, Yunnan Province, China

    Institute of Scientific and Technical Information of China (English)

    WANG Zhenhong; YANG Chengbo; YANG Limei; ZHOU Zizong; RAO Jing; YUAN Li; LI Ju

    2007-01-01

    In recent years,the relationship between biodiversity and ecosystem stability,productivity,and other ecosystem functions has been extensively studied by using theoretical approaches,experimental investigations,andobservations in natural ecosystems;however,results are controversial.For example,simple systems were more stable than complex systems in theoretical studies,and higher productivity was observed in human-made ecosystems with poorer species composition,etc.The role of biodiversity in the ecosystem,such as its influence on sustainability,stability,and productivity,is still not understood.Because accelerated soil-erosion in various ecosystems has caused a decrease of primary productivity,a logical way used in the study of the relationship between biodiversity and ecosystem function can be used to study the relationship between plant species diversity and soil conservation.In addition,biodiversity is a product of evolutionary history,and soil erosion is a key factor controlling the evolution of modern environment on the surface of the Earth.A study on the relationship between biodiversity and soil-erosion processes could help us understand the environmental evolution of Earth.Fifteen 10m × 40m standard nmoffplots were established to measure surface runoff,soil erosion,and total P loss in different secondary communities of semi-humid evergreen broad-leaved forests that varied in composition,diversity,and level of disturbance and soil erosion.The following five communities were studied:AEI (Ass.Elsholtzia fruticosa+Imperata cylindrical),APMO (Ass.Pinus yunnanensis + Myrsine africana + Oplismenus compsitus), APLO (Ass.Pinus yunnanensis + Lithocarpus confines + Oplismenus compsitus),AEME (Ass.Eucalyptus smith + Myrsine africana +Eupatorium adenophorum),and ACKV (Ass.Cyclobalanopsis glaucoides + Keteleeria evelyniana + Viola duelouxii).Tree density,the diameter of the tree at breast height,and the hygroscopic volume of plant leaves were determined in each plot

  1. Fast-cycling unit of root turnover in perennial herbaceous plants in a cold temperate ecosystem

    Science.gov (United States)

    Sun, Kai; Luke McCormack, M.; Li, Le; Ma, Zeqing; Guo, Dali

    2016-01-01

    Roots of perennial plants have both persistent portion and fast-cycling units represented by different levels of branching. In woody species, the distal nonwoody branch orders as a unit are born and die together relatively rapidly (within 1–2 years). However, whether the fast-cycling units also exist in perennial herbs is unknown. We monitored root demography of seven perennial herbs over two years in a cold temperate ecosystem and we classified the largest roots on the root collar or rhizome as basal roots, and associated finer laterals as secondary, tertiary and quaternary roots. Parallel to woody plants in which distal root orders form a fast-cycling module, basal root and its finer laterals also represent a fast-cycling module in herbaceous plants. Within this module, basal roots had a lifespan of 0.5–2 years and represented 62–87% of total root biomass, thus dominating annual root turnover (60%–81% of the total). Moreover, root traits including root length, tissue density, and biomass were useful predictors of root lifespan. We conclude that both herbaceous and woody plants have fast-cycling modular units and future studies identifying the fast-cycling module across plant species should allow better understanding of how root construction and turnover are linked to whole-plant strategies.

  2. Environmental and community controls on plant canopy chemistry in a Mediterranean-type ecosystem.

    Science.gov (United States)

    Dahlin, Kyla M; Asner, Gregory P; Field, Christopher B

    2013-04-23

    Understanding how and why plant communities vary across space has long been a goal of ecology, yet parsing the relative importance of different influences has remained a challenge. Species-specific models are not generalizable, whereas broad plant functional type models lack important detail. Here we consider plant trait patterns at the local scale and ask whether plant chemical traits are more closely linked to environmental gradients or to changes in species composition. We used the visible-to-shortwave infrared (VSWIR) spectrometer of the Carnegie Airborne Observatory to develop maps of four plant chemical traits--leaf nitrogen per mass, leaf carbon per mass, leaf water concentration, and canopy water content--across a diverse Mediterranean-type ecosystem (Jasper Ridge Biological Preserve, CA). For all four traits, plant community alone was the strongest predictor of trait variation (explaining 46-61% of the heterogeneity), whereas environmental gradients accounted for just one fourth of the variation in the traits. This result emphasizes the critical role that species composition plays in mediating nutrient and carbon cycling within and among different communities. Environmental filtering and limits to similarity can act strongly, simultaneously, in a spatially heterogeneous environment, but the local-scale environmental gradients alone cannot account for the variation across this landscape.

  3. Conditions for global dynamic stability of a class of resource-bounded model ecosystems.

    Science.gov (United States)

    Seymour, Robert M; Knight, Gwenan; Fung, Tak

    2010-11-01

    This paper studies a class of dynamical systems that model multi-species ecosystems. These systems are 'resource bounded' in the sense that species compete to utilize an underlying limiting resource or substrate. This boundedness means that the relevant state space can be reduced to a simplex, with coordinates representing the proportions of substrate utilized by the various species. If the vector field is inward pointing on the boundary of the simplex, the state space is forward invariant under the system flow, a requirement that can be interpreted as the presence of non-zero exogenous recruitment. We consider conditions under which these model systems have a unique interior equilibrium that is globally asymptotically stable. The systems we consider generalize classical multi-species Lotka-Volterra systems, the behaviour of which is characterized by properties of the community (or interaction) matrix. However, the more general systems considered here are not characterized by a single matrix, but rather a family of matrices. We develop a set of 'explicit conditions' on the basis of a notion of 'uniform diagonal dominance' for such a family of matrices, that allows us to extract a set of sufficient conditions for global asymptotic stability based on properties of a single, derived matrix. Examples of these explicit conditions are discussed.

  4. Extraordinary stability of copper(I)-tetrathiomolybdate complexes: possible implications for aquatic ecosystems.

    Science.gov (United States)

    Helz, George R; Erickson, Britt E

    2011-01-01

    An extraordinary affinity of MoS₄²⁻ for Cu accounts for Mo-induced Cu deficiency in ruminants (molybdenosis) and offers an approach to treating Wilson's disease in humans. Evidence of thiomolybdates in sulfidic natural waters, and possibly even as metastable traces in oxic natural waters, raises the question of how Cu-Mo affinity might affect Cu availability or toxicity in aquatic ecosystems. Stabilities of inorganic Cu-MoS₄²⁻ complexes are characterized and quantified here for the first time. Two remarkably stable Cu(I) dissolved complexes are identified (T = 23°C ± 2°C): Cu₂(HS)₂MoS₄²⁻ and Cu₂S₂MoS₄⁴⁻. In addition, the solubility constant for a precipitate (NH₄CuMoS₄) was measured. Under the extremely reducing conditions in rumen fluids, these complexes will greatly suppress Cu(+) activity, supporting prior conclusions about the mechanism of molybdenosis. In sulfidic natural waters, they help to prevent complete Cu impoverishment, as might otherwise occur by sulfide mineral precipitation. On the other hand, the complexes discovered here are HS⁻-dependent and could not be important in oxic natural waters (with HS⁻ concentrations < 10⁻⁹ M) even if metastable, biogenic MoS₄²⁻ indeed were present as previously conjectured.

  5. Regional signatures of plant response to drought and elevated temperature across a desert ecosystem.

    Science.gov (United States)

    Munson, Seth M; Muldavin, Esteban H; Belnap, Jayne; Peters, Debra P C; Anderson, John P; Reiser, M Hildegard; Gallo, Kirsten; Melgoza-Castillo, Alicia; Herrick, Jeffrey E; Christiansen, Tim A

    2013-09-01

    The performance of many desert plant species in North America may decline with the warmer and drier conditions predicted by climate change models, thereby accelerating land degradation and reducing ecosystem productivity. We paired repeat measurements of plant canopy cover with climate at multiple sites across the Chihuahuan Desert over the last century to determine which plant species and functional types may be the most sensitive to climate change. We found that the dominant perennial grass, Bouteloua eriopoda, and species richness had nonlinear responses to summer precipitation, decreasing more in dry summers than increasing with wet summers. Dominant shrub species responded differently to the seasonality of precipitation and drought, but winter precipitation best explained changes in the cover of woody vegetation in upland grasslands and may contribute to woody-plant encroachment that is widespread throughout the southwestern United States and northern Mexico. Temperature explained additional variability of changes in cover of dominant and subdominant plant species. Using a novel empirically based approach we identified "climate pivot points" that were indicative of shifts from increasing to decreasing plant cover over a range of climatic conditions. Reductions in cover of annual and several perennial plant species, in addition to declines in species richness below the long-term summer precipitation mean across plant communities, indicate a decrease in the productivity for all but the most drought-tolerant perennial grasses and shrubs in the Chihuahuan Desert. Overall, our regional synthesis of long-term data provides a robust foundation for forecasting future shifts in the composition and structure of plant assemblages in the largest North American warm desert.

  6. Non-native plants and soil microbes: potential contributors to the consistent reduction in soil aggregate stability caused by the disturbance of North American grasslands.

    Science.gov (United States)

    Duchicela, Jessica; Vogelsang, Keith M; Schultz, Peggy A; Kaonongbua, Wittaya; Middleton, Elizabeth L; Bever, James D

    2012-10-01

    • Soil aggregate stability is an important ecosystem property that is altered by anthropogenic disturbance. Yet, the generalization of these alterations and the identification of the main contributors are limited by the absence of cross-site comparisons and the application of inconsistent methodologies across regions. • We assessed aggregate stability in paired remnant and post-disturbance grasslands across California, shortgrass and tallgrass prairies, and in manipulative experiments of plant composition and soil microbial inoculation. • Grasslands recovering from anthropogenic disturbance consistently had lower aggregate stability than remnants. Across all grasslands, non-native plant diversity was significantly associated with reduced soil aggregate stability. A negative effect of non-native plants on aggregate stability was also observed in a mesocosm experiment comparing native and non-native plants from California grasslands. Moreover, an inoculation study demonstrated that the degradation of the microbial community also contributes to the decline in soil aggregate stability in disturbed grasslands. • Anthropogenic disturbance consistently reduced water-stable aggregates. The stability of aggregates was reduced by non-native plants and the degradation of the native soil microbial community. This latter effect might contribute to the sustained decline in aggregate stability following anthropogenic disturbance. Further exploration is advocated to understand the generality of these potential mechanisms.

  7. Isoscapes resolve species-specific spatial patterns in plant-plant interactions in an invaded Mediterranean dune ecosystem.

    Science.gov (United States)

    Hellmann, Christine; Rascher, Katherine G; Oldeland, Jens; Werner, Christiane

    2016-12-01

    Environmental heterogeneity and plant-plant interactions are key factors shaping plant communities. However, the spatial dimension of plant-plant interactions has seldom been addressed in field studies. This is at least partially rooted in a lack of methods that can accurately resolve functional processes in a spatially explicit manner. Isoscapes, that is, spatially explicit representations of stable isotope data, provide a versatile means to trace functional changes on spatial scales, for example, related to N-cycling (foliar δ(15)N) and water use efficiency (WUEi, foliar δ(13)C). In a case study in a nutrient-depleted Mediterranean dune ecosystem, we analysed the spatial impact of the invasive N2-fixing Acacia longifolia on three native species of different functional types using δ(15)N and δ(13)C isoscapes and spatial autocorrelation analyses. Isoscapes revealed strong spatial patterns in δ(15)N and δ(13)C with pronounced species-specific differences, demonstrating distinct spatial ranges of plant-plant interactions. A coniferous tree and an ericaceous dwarf shrub showed significant enrichment in δ(15)N within a range of 5-8 m surrounding the canopy of A. longifolia, indicating input of N originating from symbiotic N2-fixation by the invader. In the dwarf shrub, which was most responsive to invader influence, enrichment in δ(13)C additionally demonstrated spatially explicit changes to WUEi, while a native N2-fixer was unresponsive to the presence of the invader. Furthermore, δ(15)N and δ(13)C isoscapes yielded different patterns, indicating that plant-plant interactions can have distinct spatial distributions and ranges based on the process measured. Additionally, the magnitude of the effect differed between field situations with high and low invasion pressure. This study highlights that the spatial scale must be accounted for when assessing the effects and outcome of species interactions. Functional tracers such as stable isotopes enable us to

  8. New challenges for the design of high value plant products: stabilization of anthocyanins in plant vacuoles

    Directory of Open Access Journals (Sweden)

    Valentina ePasseri

    2016-02-01

    Full Text Available In the last decade plant biotechnologists and breeders have made several attempt to improve the antioxidant content of plant-derived food. Most efforts concentrated on increasing the synthesis of antioxidants, in particular anthocyanins, by inducing the transcription of genes encoding the synthesizing enzymes. We present here an overview of economically interesting plant species, both food crops and ornamentals, in which anthocyanin content was improved by traditional breeding or transgenesis. Old genetic studies in petunia and more recent biochemical work in brunfelsia, have shown that after synthesis and compartmentalization in the vacuole, anthocyanins need to be stabilized to preserve the color of the plant tissue over time. The final yield of antioxidant molecules is the result of the balance between synthesis and degradation. Therefore the understanding of the mechanism that determine molecule stabilization in the vacuolar lumen is the next step that needs to be taken to further improve the anthocyanin content in food.In several species a phenomenon known as fading is responsible for the disappearance of pigmentation which in some case can be nearly complete. We discuss the present knowledge about the genetic and biochemical factors involved in pigment preservation/destabilization in plant cells.The improvement of our understanding of the fading process will supply new tools for both biotechnological approaches and marker-assisted breeding.

  9. New Challenges for the Design of High Value Plant Products: Stabilization of Anthocyanins in Plant Vacuoles.

    Science.gov (United States)

    Passeri, Valentina; Koes, Ronald; Quattrocchio, Francesca M

    2016-01-01

    In the last decade plant biotechnologists and breeders have made several attempt to improve the antioxidant content of plant-derived food. Most efforts concentrated on increasing the synthesis of antioxidants, in particular anthocyanins, by inducing the transcription of genes encoding the synthesizing enzymes. We present here an overview of economically interesting plant species, both food crops and ornamentals, in which anthocyanin content was improved by traditional breeding or transgenesis. Old genetic studies in petunia and more recent biochemical work in brunfelsia, have shown that after synthesis and compartmentalization in the vacuole, anthocyanins need to be stabilized to preserve the color of the plant tissue over time. The final yield of antioxidant molecules is the result of the balance between synthesis and degradation. Therefore the understanding of the mechanism that determine molecule stabilization in the vacuolar lumen is the next step that needs to be taken to further improve the anthocyanin content in food. In several species a phenomenon known as fading is responsible for the disappearance of pigmentation which in some case can be nearly complete. We discuss the present knowledge about the genetic and biochemical factors involved in pigment preservation/destabilization in plant cells. The improvement of our understanding of the fading process will supply new tools for both biotechnological approaches and marker-assisted breeding.

  10. Sustainable utilization and conservation of plant biodiversity in montane ecosystems: the western Himalayas as a case study

    Science.gov (United States)

    Khan, Shujaul Mulk; Page, Sue E.; Ahmad, Habib; Harper, David M.

    2013-01-01

    Background Conservation of the unique biodiversity of mountain ecosystems needs trans-disciplinary approaches to succeed in a crowded colloquial world. Geographers, conservationists, ecologists and social scientists have, in the past, had the same conservation goals but have tended to work independently. In this review, the need to integrate different conservation criteria and methodologies is discussed. New criteria are offered for prioritizing species and habitats for conservation in montane ecosystems that combine both ecological and social data. Scope Ecological attributes of plant species, analysed through robust community statistical packages, provide unbiased classifications of species assemblages and environmental biodiversity gradients and yield importance value indices (IVIs). Surveys of local communities’ utilization of the vegetation provides use values (UVs). This review suggests a new means of assessing anthropogenic pressure on plant biodiversity at both species and community levels by integrating IVI and UV data sets in a combined analysis. Conclusions Mountain ecosystems are hot spots for plant conservation efforts because they hold a high overall plant diversity as communities replace each other along altitudinal and climatic gradients, including a high proportion of endemic species. This review contributes an enhanced understanding of (1) plant diversity in mountain ecosystems with special reference to the western Himalayas; (2) ethnobotanical and ecosystem service values of mountain vegetation within the context of anthropogenic impacts; and (3) local and regional plant conservation strategies and priorities. PMID:23825353

  11. Ammonium as a driving force of plant diversity and ecosystem functioning: observations based on 5 years' manipulation of N dose and form in a Mediterranean ecosystem.

    Science.gov (United States)

    Dias, Teresa; Clemente, Adelaide; Martins-Loução, Maria Amélia; Sheppard, Lucy; Bobbink, Roland; Cruz, Cristina

    2014-01-01

    Enhanced nitrogen (N) availability is one of the main drivers of biodiversity loss and degradation of ecosystem functions. However, in very nutrient-poor ecosystems, enhanced N input can, in the short-term, promote diversity. Mediterranean Basin ecosystems are nutrient-limited biodiversity hotspots, but no information is available on their medium- or long-term responses to enhanced N input. Since 2007, we have been manipulating the form and dose of available N in a Mediterranean Basin maquis in south-western Europe that has low ambient N deposition (plant composition and diversity (richness and evenness) and some ecosystem characteristics (soil extractable N and organic matter, aboveground biomass and % of bare soil) were assessed. Plant species richness increased with enhanced N input and was more related to ammonium than to nitrate. Exposure to 40 kg NH4+-N ha(-1) yr(-1) (alone and with nitrate) enhanced plant richness, but did not increase aboveground biomass; soil extractable N even increased under 80 kg NH4NO3-N ha(-1) yr(-1) and the % of bare soil increased under 40 kg NH4+-N ha(-1) yr(-1). The treatment containing less ammonium, 40 kg NH4NO3-N ha(-1) yr(-1), did not enhance plant diversity but promoted aboveground biomass and reduced the % of bare soil. Data suggest that enhanced NHy availability affects the structure of the maquis, which may promote soil erosion and N leakage, whereas enhanced NOx availability leads to biomass accumulation which may increase the fire risk. These observations are relevant for land use management in biodiverse and fragmented ecosystems such as the maquis, especially in conservation areas.

  12. Do biotic interactions modulate ecosystem functioning along stress gradients? Insights from semi-arid plant and biological soil crust communities

    Science.gov (United States)

    Maestre, Fernando T.; Bowker, Matthew A.; Escolar, Cristina; Puche, María D.; Soliveres, Santiago; Maltez-Mouro, Sara; García-Palacios, Pablo; Castillo-Monroy, Andrea P.; Martínez, Isabel; Escudero, Adrián

    2010-01-01

    Climate change will exacerbate the degree of abiotic stress experienced by semi-arid ecosystems. While abiotic stress profoundly affects biotic interactions, their potential role as modulators of ecosystem responses to climate change is largely unknown. Using plants and biological soil crusts, we tested the relative importance of facilitative–competitive interactions and other community attributes (cover, species richness and species evenness) as drivers of ecosystem functioning along stress gradients in semi-arid Mediterranean ecosystems. Biotic interactions shifted from facilitation to competition along stress gradients driven by water availability and temperature. These changes were, however, dependent on the spatial scale and the community considered. We found little evidence to suggest that biotic interactions are a major direct influence upon indicators of ecosystem functioning (soil respiration, organic carbon, water-holding capacity, compaction and the activity of enzymes related to the carbon, nitrogen and phosphorus cycles) along stress gradients. However, attributes such as cover and species richness showed a direct effect on ecosystem functioning. Our results do not agree with predictions emphasizing that the importance of plant–plant interactions will be increased under climate change in dry environments, and indicate that reductions in the cover of plant and biological soil crust communities will negatively impact ecosystems under future climatic conditions. PMID:20513714

  13. Applications of stable isotopes to study plant-animal relationships in terrestrial ecosystems

    Institute of Scientific and Technical Information of China (English)

    WANG Jianzhu; LIN Guanghui; HUANG Jianhui; HAN Xingguo

    2004-01-01

    As natural tracers, stable isotopes have been extensively used in plant physiological, ecological and environmental research. Recently, animal physiological ecologists have also applied stable isotope techniques to study plant- animal relationships. The isotopic compositions of animal body generally reflect and integrate their diets over a time period ranging from hours to years to the lifetime of an individual. When animal living habitat changes or animals move to a new environment, the animal isotopic compositions will shift accordingly. Thus, stable isotope signatures of an animal can truly reflect its food sources, habitat, distribution and movement patterns during a given time period. Moreover, by analyzing animal-tissue isotopic compositions at different temporal scales, we can improve our understanding of animal adaptation to environmental changes. Stable isotope technique also provides an ideal tool to study animal foodweb relationship and community structure because of isotopic fractionation during the processes of nutrient assimilation by animals. Stable isotope technique can continuously measure animal trophic position in a foodweb, which can eventually reveal the predator-prey relationship and its role in determining matter balance and energy flow in the entire ecosystem. Stable isotope technique has been one of the most important and efficient tools in studying plant-animal relationship. In this paper, we first review recent advances in the application of stable isotope techniques to plant-animal relationship research then evaluate their advantages and disadvantages, and finally discuss some future directions associated with stable isotope applications to plant-animal relationship research.

  14. Herbivores, the Functional Diversity of Plants Species, and the Cycling of Nutrients in Ecosystems

    Science.gov (United States)

    Pastor; Cohen

    1997-06-01

    Numerous investigators have suggested that herbivores almost always increase rates of nutrient and energy flow through terrestrial ecosystems by returning to the soil fecal material and urine with faster turnover rate than shed plant litter. These previous theories and models always treat the producer compartment as a homogenous pool. Essentially, they assume that consumers feed through a pureed cream of vegetable soup. However, many field observations and experiments have shown that consumers feed selectively (i.e., in a cafeteria) and that consumer choice is made on the same chemical basis that determines decomposition rates. Plants that are preferred food sources often have higher nutrient content, higher growth rates, and faster decomposition rates. As consumption reduces dominance of these species in favor of unpreferred species with slower decomposition, rates of nutrient cycling and energy flow should therefore decline. We analyze a model in which the consumer is given a choice among producers that vary in nutrient uptake rates, rates of nutrient return to decomposers, and consumer preference, and which is parameterized for plants and consumers characteristic of boreal regions. In this model, in an open, well-mixed system with one consumer and two such producers, the nutrient/energy flow will not exceed that of a system without the consumer. If the consumer has a choice between two such producers, it must choose one plant over the other at a greater ratio than that between the two plants in uptake and decay rates. In contrast, in a closed system the consumer must be less selective to coexist with the two plants. The system behavior is determined by the level of nutrient return through the consumer and the differences between the plants in nutrient uptake rates and consumer preference. Species richness affects properties of this model system to the extent that species are functionally distinct (i.e., have different rate constants) in a multivariate space of

  15. Multiple plant-wax compounds record differential sources and ecosystem structure in large river catchments

    Science.gov (United States)

    Hemingway, Jordon D.; Schefuß, Enno; Dinga, Bienvenu Jean; Pryer, Helena; Galy, Valier V.

    2016-07-01

    The concentrations, distributions, and stable carbon isotopes (δ13C) of plant waxes carried by fluvial suspended sediments contain valuable information about terrestrial ecosystem characteristics. To properly interpret past changes recorded in sedimentary archives it is crucial to understand the sources and variability of exported plant waxes in modern systems on seasonal to inter-annual timescales. To determine such variability, we present concentrations and δ13C compositions of three compound classes (n-alkanes, n-alcohols, n-alkanoic acids) in a 34-month time series of suspended sediments from the outflow of the Congo River. We show that exported plant-dominated n-alkanes (C25-C35) represent a mixture of C3 and C4 end members, each with distinct molecular distributions, as evidenced by an 8.1 ± 0.7‰ (±1σ standard deviation) spread in δ13C values across chain-lengths, and weak correlations between individual homologue concentrations (r = 0.52-0.94). In contrast, plant-dominated n-alcohols (C26-C36) and n-alkanoic acids (C26-C36) exhibit stronger positive correlations (r = 0.70-0.99) between homologue concentrations and depleted δ13C values (individual homologues average ⩽-31.3‰ and -30.8‰, respectively), with lower δ13C variability across chain-lengths (2.6 ± 0.6‰ and 2.0 ± 1.1‰, respectively). All individual plant-wax lipids show little temporal δ13C variability throughout the time-series (1σ ⩽ 0.9‰), indicating that their stable carbon isotopes are not a sensitive tracer for temporal changes in plant-wax source in the Congo basin on seasonal to inter-annual timescales. Carbon-normalized concentrations and relative abundances of n-alcohols (19-58% of total plant-wax lipids) and n-alkanoic acids (26-76%) respond rapidly to seasonal changes in runoff, indicating that they are mostly derived from a recently entrained local source. In contrast, a lack of correlation with discharge and low, stable relative abundances (5-16%) indicate that

  16. Effect of sustainable land management practices on soil aggregation and stabilization of organic carbon in semiarid mediterranean ecosystems

    Science.gov (United States)

    Garcia-Franco, Noelia; Albaladejo, Juan; Almagro, María; Wiesmeier, Martin; Martínez-Mena, María

    2016-04-01

    Arid and semiarid regions represent about 47% of the total land area of the world (UNEP, 1992). At present, there is a priority interest for carbon (C) sequestration in drylands. These areas are considered as very fragile ecosystems with low organic carbon (OC) saturation, and potentially, high capacity for soil OC sequestration. In addition, the restoration of these areas is one of the major challenges for scientists, who will be able to identify and recommended the best land uses and sustainable land management (SLM) practices for soil conservation and mitigation of climate change in these environments. In this regard, in semiarid Mediterranean ecosystems there is an urgent need for the implementation of SLM practices regardless of land-use type (forest, agricultural and shrubland) to maintain acceptable levels of soil organic matter (SOM) and the physico-chemical protection of the OC. Long- and short-term effects of SLM practices on soil aggregation and SOC stabilization were studied in two land uses. The long-term experiment was conducted in a reforestation area with Pinus halepensis Mill., where two afforestation techniques were implemented 20 years ago: a) mechanical terracing with a single application of organic waste of urban soil refuse, and b) mechanical terracing without organic amendment. An adjacent shrubland was considered as the reference plot. The short-term experiment was conducted in a rain-fed almond (Prunus dulcis Mill., var. Ferragnes) orchard where two SLM practices were introduced 4 years ago: a) reduced tillage plus green manure, and b) no tillage. Reduced tillage was considered as the reference plot given that it is the habitual management practice. Four aggregate size classes were differentiated by sieving (large and small macroaggregates, microaggregates, and the silt plus clay fraction), and the microaggregates occluded within small macroaggregates (SMm) were isolated. In addition, different organic C fractions corresponding with active

  17. Influence of productivity on the stability of real and model ecosystems

    Energy Technology Data Exchange (ETDEWEB)

    Moore, J.C. (Univ. of Northern Colorado, Greeley, CO (United States)); Ruiter, P.C. de (DLO-Institute for Soil Fertility Research, Groningen (Netherlands)); Hunt, H.W. (Colorado State Univ., Fort Collins, CO (United States))

    1993-08-13

    The lengths of food chains within ecosystems have been thought to be limited either by the productivity of the ecosystem or by the resilience of that ecosystem after perturbation. Models based on ecological energetics that follow the form of Lotka-Volterra equations and equations that include material (detritus) recycling show that productivity and resilience are inextricably interrelated. The models were initialized with data from 5- to 10-year studies of actual soil food webs. Estimates indicate that most ecological production worldwide is from ecosystems that are themselves sufficiently productive to recover from minor perturbations.

  18. Quantifying Ecological Memory of Plant and Ecosystem Processes in Variable Environments

    Science.gov (United States)

    Ogle, K.; Barron-Gafford, G. A.; Bentley, L.; Cable, J.; Lucas, R.; Huxman, T. E.; Loik, M. E.; Smith, S. D.; Tissue, D.

    2010-12-01

    Precipitation, soil water, and other factors affect plant and ecosystem processes at multiple time scales. A common assumption is that water availability at a given time directly affects processes at that time. Recent work, especially in pulse-driven, semiarid systems, shows that antecedent water availability, averaged over several days to a couple weeks, can be just as or more important than current water status. Precipitation patterns of previous seasons or past years can also impact plant and ecosystem functioning in many systems. However, we lack an analytical framework for quantifying the importance of and time-scale over which past conditions affect current processes. This study explores the ecological memory of a variety of plant and ecosystem processes. We use memory as a metaphor to describe the time-scale over which antecedent conditions affect the current process. Existing approaches for incorporating antecedent effects arbitrarily select the antecedent integration period (e.g., the past 2 weeks) and the relative importance of past conditions (e.g., assign equal or linearly decreasing weights to past events). In contrast, we utilize a hierarchical Bayesian approach to integrate field data with process-based models, yielding posterior distributions for model parameters, including the duration of the ecological memory (integration period) and the relative importance of past events (weights) to this memory. We apply our approach to data spanning diverse temporal scales and four semiarid sites in the western US: leaf-level stomatal conductance (gs, sub-hourly scale), soil respiration (Rs, hourly to daily scale), and net primary productivity (NPP) and tree-ring widths (annual scale). For gs, antecedent factors (daily rainfall and temperature, hourly vapor pressure deficit) and current soil water explained up to 72% of the variation in gs in the Chihuahuan Desert, with a memory of 10 hours for a grass and 4 days for a shrub. Antecedent factors (past soil water

  19. Multi-year estimates of plant and ecosystem 13C discrimination at AmeriFlux sites

    Science.gov (United States)

    Dang, X.; Lai, C.; Hollinger, D. Y.; Bush, S.; Randerson, J. T.; Law, B. E.; Schauer, A. J.; Ehleringer, J.

    2011-12-01

    We estimated plant and ecosystem 13C discrimination continuously at 8 AmeriFlux sites (Howland Forest, Harvard Forest, Wind River Forest, Rannells Prairie, Freeman Ranch, Chestnut Ridge, Metolius, and Marys River fir) over 8 years (2002-2009). We used an observation-based approach from weekly measurements of eddy covariance CO2 fluxes and their 13C/12C ratios to estimate photosynthetic 13C discrimination (△A) and respiration (δ13CR) on seasonal and interannual time scales. The coordinated, systematic flask sampling across the AmeriFlux subnetwork were used for cross-site synthesis of monthly flux estimates [Dang et al. Combining tower mixing ratio and community model data to estimate regional-scale net ecosystem carbon exchange by boundary layer inversion over 4 flux towers in the U.S.A., Journal of Geophysical Research-Biogeosciences, in press]. Here, we evaluated environmental factors that also influenced temporal variability in △A and δ13CR from daily to interannual time scales, comparing atmospheric 13C/12C measurements, leaf and needle organic matter, and tree ring cellulose. Across these major biomes that dominate the continent, we show differential ecophysiological responses to environmental stresses, among which water availability appeared to be a dominant factor. Our decadal measurement period provided robust estimates of atmospheric 13C discrimination by terrestrial ecosystems, but also suggest regions where enhanced monitoring efforts are required (e.g., 13C/12C emission from fire and urban metabolism; increased temporal resolution of 13C measurements in stress-sensitive ecosystems) to make atmospheric 13C/12C measurements an effective constraint for continental-scale assessments of the terrestrial carbon cycle.

  20. Dynamics of microbial communities during decomposition of litter from pioneering plants in initial soil ecosystems

    Science.gov (United States)

    Esperschütz, J.; Zimmermann, C.; Dümig, A.; Welzl, G.; Buegger, F.; Elmer, M.; Munch, J. C.; Schloter, M.

    2013-07-01

    In initial ecosystems, concentrations of all macro- and micronutrients can be considered as extremely low. Plant litter therefore strongly influences the development of a degrader's food web and is an important source for C and N input into soil in such ecosystems. In the present study, a 13C litter decomposition field experiment was performed for 30 weeks in initial soils from a post-mining area near the city of Cottbus (Germany). Two of this region's dominant but contrasting pioneering plant species (Lotus corniculatus L. and Calamagrostis epigejos L.) were chosen to investigate the effects of litter quality on the litter decomposing microbial food web in initially nutrient-poor substrates. The results clearly indicate the importance of litter quality, as indicated by its N content, its bioavailability for the degradation process and the development of microbial communities in the detritusphere and soil. The degradation of the L. corniculatus litter, which had a low C / N ratio, was fast and showed pronounced changes in the microbial community structure 1-4 weeks after litter addition. The degradation of the C. epigejos litter material was slow and microbial community changes mainly occurred between 4 and 30 weeks after litter addition to the soil. However, for both litter materials a clear indication of the importance of fungi for the degradation process was observed both in terms of fungal abundance and activity (13C incorporation activity)

  1. Dynamics of microbial communities during decomposition of litter from pioneering plants in initial soil ecosystems

    Directory of Open Access Journals (Sweden)

    J. Esperschütz

    2013-07-01

    Full Text Available In initial ecosystems, concentrations of all macro- and micronutrients can be considered as extremely low. Plant litter therefore strongly influences the development of a degrader's food web and is an important source for C and N input into soil in such ecosystems. In the present study, a 13C litter decomposition field experiment was performed for 30 weeks in initial soils from a post-mining area near the city of Cottbus (Germany. Two of this region's dominant but contrasting pioneering plant species (Lotus corniculatus L. and Calamagrostis epigejos L. were chosen to investigate the effects of litter quality on the litter decomposing microbial food web in initially nutrient-poor substrates. The results clearly indicate the importance of litter quality, as indicated by its N content, its bioavailability for the degradation process and the development of microbial communities in the detritusphere and soil. The degradation of the L. corniculatus litter, which had a low C / N ratio, was fast and showed pronounced changes in the microbial community structure 1–4 weeks after litter addition. The degradation of the C. epigejos litter material was slow and microbial community changes mainly occurred between 4 and 30 weeks after litter addition to the soil. However, for both litter materials a clear indication of the importance of fungi for the degradation process was observed both in terms of fungal abundance and activity (13C incorporation activity

  2. Effects of an invasive plant transcend ecosystem boundaries through a dragonfly-mediated trophic pathway.

    Science.gov (United States)

    Burkle, Laura A; Mihaljevic, Joseph R; Smith, Kevin G

    2012-12-01

    Trophic interactions can strongly influence the structure and function of terrestrial and aquatic communities through top-down and bottom-up processes. Species with life stages in both terrestrial and aquatic systems may be particularly likely to link the effects of trophic interactions across ecosystem boundaries. Using experimental wetlands planted with purple loosestrife (Lythrum salicaria), we tested the degree to which the bottom-up effects of floral density of this invasive plant could trigger a chain of interactions, changing the behavior of terrestrial flying insect prey and predators and ultimately cascading through top-down interactions to alter lower trophic levels in the aquatic community. The results of our experiment support the linkage of terrestrial and aquatic food webs through this hypothesized pathway, with high loosestrife floral density treatments attracting high levels of visiting insect pollinators and predatory adult dragonflies. High floral densities were also associated with increased adult dragonfly oviposition and subsequently high larval dragonfly abundance in the aquatic community. Finally, high-flower treatments were coupled with changes in zooplankton species richness and shifts in the composition of zooplankton communities. Through changes in animal behavior and trophic interactions in terrestrial and aquatic systems, this work illustrates the broad and potentially cryptic effects of invasive species, and provides additional compelling motivation for ecologists to conduct investigations that cross traditional ecosystem boundaries.

  3. Plutonium Finishing Plant. Interim plutonium stabilization engineering study

    Energy Technology Data Exchange (ETDEWEB)

    Sevigny, G.J.; Gallucci, R.H.; Garrett, S.M.K.; Geeting, J.G.H.; Goheen, R.S.; Molton, P.M.; Templeton, K.J.; Villegas, A.J. [Pacific Northwest Lab., Richland, WA (United States); Nass, R. [Nuclear Fuel Services, Inc. (United States)

    1995-08-01

    This report provides the results of an engineering study that evaluated the available technologies for stabilizing the plutonium stored at the Plutonium Finishing Plant located at the hanford Site in southeastern Washington. Further processing of the plutonium may be required to prepare the plutonium for interim (<50 years) storage. Specifically this document provides the current plutonium inventory and characterization, the initial screening process, and the process descriptions and flowsheets of the technologies that passed the initial screening. The conclusions and recommendations also are provided. The information contained in this report will be used to assist in the preparation of the environmental impact statement and to help decision makers determine which is the preferred technology to process the plutonium for interim storage.

  4. Response of an invasive native wetland plant to environmental flows: implications for managing regulated floodplain ecosystems.

    Science.gov (United States)

    Vivian, Lyndsey M; Marshall, David J; Godfree, Robert C

    2014-01-01

    The natural flow regimes of rivers underpin the health and function of floodplain ecosystems. However, infrastructure development and the over-extraction of water has led to the alteration of natural flow regimes, resulting in the degradation of river and floodplain habitats globally. In many catchments, including Australia's Murray-Darling Basin, environmental flows are seen as a potentially useful tool to restore natural flow regimes and manage the degradation of rivers and their associated floodplains. In this paper, we investigated whether environmental flows can assist in controlling an invasive native floodplain plant in Barmah Forest, south-eastern Australia. We experimentally quantified the effects of different environmental flow scenarios, including a shallow (20 cm) and deeper (50 cm) flood of different durations (12 and 20 weeks), as well as drought and soil-saturated conditions, on the growth and survival of seedlings of Juncus ingens, a native emergent macrophyte that has become invasive in some areas of Barmah Forest following river regulation and alteration of natural flow regimes. Three height classes of J. ingens (33 cm, 17 cm and 12 cm) were included in the experiment to explicitly test for relationships between treatments, plant survival and growth, and plant height. We found that seedling mortality occurred in the drought treatment and in the 20-week flood treatments of both depths; however, mortality rates in the flood treatments depended on initial plant height, with medium and short plants (initial heights of ≤17 cm) exhibiting the highest mortality rates. Both the 20 cm and 50 cm flood treatments of only 12 weeks duration were insufficient to cause mortality in any of the height classes; indeed, shoots of plants in the 20 cm flood treatment were able to elongate through the water surface at rapid rates. Our findings have important implications for management of Barmah Forest and floodplain ecosystems elsewhere, as it demonstrates

  5. How Plant Hydraulics can Improve the Modeling of Plant and Ecosystem Responses to Environment

    Science.gov (United States)

    Sperry, J.; Anderegg, W.; Mackay, D. S.; Venturas, M.

    2016-12-01

    Stomatal regulation is an important, yet problematic component in modeling plant-environment interactions. The problem is that stomata respond to so many environmental cues via complex and uncertain mechanisms. But the assumed end result of regulation is conceptually simple: an optimization of CO2 for H2O exchange in response to changing conditions. Stomata open when photosynthetic opportunity is high and water is cheap. They close if photosynthetic opportunity is low or water is very expensive. Photosynthetic opportunity is relatively easy to model. The cost of water loss is also easy to model if it is assumed to rise with greater proximity to hydraulic failure and desiccation. Unsaturated hydraulic conductivity curves of soil- and plant are used to estimate proximity to failure. At any given instant, a model can calculate opportunity and cost curves associated with greater stomatal opening. If stomata regulate to maximize the instantaneous difference between photosynthetic gain and hydraulic cost, then a model can predict the trajectory of stomatal responses to changes in environment across time. Results of this optimization routine extend the utility of hydraulic predecessor models, and are consistent with widely used empirical models across a wide range of vapor pressure deficit and ambient CO2 concentrations for wet soil. The advantage of the optimization approach is the absence of empirical coefficients, applicability to dry as well as wet soil, and prediction of plant hydraulic status along with gas exchange. The optimization algorithm is a trait- and process-based approach that could improve next generation land surface models.

  6. Hyperspectral remote sensing application for monitoring and preservation of plant ecosystems

    Science.gov (United States)

    Krezhova, Dora; Maneva, Svetla; Zdravev, Tomas; Petrov, Nikolay; Stoev, Antoniy

    Remote sensing technologies have advanced significantly at last decade and have improved the capability to gather information about Earth’s resources and environment. They have many applications in Earth observation, such as mapping and updating land-use and cover, weather forecasting, biodiversity determination, etc. Hyperspectral remote sensing offers unique opportunities in the environmental monitoring and sustainable use of natural resources. Remote sensing sensors on space-based platforms, aircrafts, or on ground, are capable of providing detailed spectral, spatial and temporal information on terrestrial ecosystems. Ground-based sensors are used to record detailed information about the land surface and to create a data base for better characterizing the objects which are being imaged by the other sensors. In this paper some applications of two hyperspectral remote sensing techniques, leaf reflectance and chlorophyll fluorescence, for monitoring and assessment of the effects of adverse environmental conditions on plant ecosystems are presented. The effect of stress factors such as enhanced UV-radiation, acid rain, salinity, viral infections applied to some young plants (potato, pea, tobacco) and trees (plums, apples, paulownia) as well as of some growth regulators were investigated. Hyperspectral reflectance and fluorescence data were collected by means of a portable fiber-optics spectrometer in the visible and near infrared spectral ranges (450-850 nm and 600-900 nm), respectively. The differences between the reflectance data of healthy (control) and injured (stressed) plants were assessed by means of statistical (Student’s t-criterion), first derivative, and cluster analysis and calculation of some vegetation indices in four most informative for the investigated species regions: green (520-580 nm), red (640-680 nm), red edge (690-720 nm) and near infrared (720-780 nm). Fluorescence spectra were analyzed at five characteristic wavelengths located at the

  7. Hyperspectral remote sensing tools for quantifying plant litter and invasive species in arid ecosystems

    Science.gov (United States)

    Nagler, Pamela L.; Sridhar, B.B. Maruthi; Olsson, Aaryn Dyami; Glenn, Edward P.; van Leeuwen, Willem J.D.; Thenkabail, Prasad S.; Huete, Alfredo; Lyon, John G.

    2012-01-01

    Green vegetation can be distinguished using visible and infrared multi-band and hyperspectral remote sensing methods. The problem has been in identifying and distinguishing the non-photosynthetically active radiation (PAR) landscape components, such as litter and soils, and from green vegetation. Additionally, distinguishing different species of green vegetation is challenging using the relatively few bands available on most satellite sensors. This chapter focuses on hyperspectral remote sensing characteristics that aim to distinguish between green vegetation, soil, and litter (or senescent vegetation). Quantifying litter by remote sensing methods is important in constructing carbon budgets of natural and agricultural ecosystems. Distinguishing between plant types is important in tracking the spread of invasive species. Green leaves of different species usually have similar spectra, making it difficult to distinguish between species. However, in this chapter we show that phenological differences between species can be used to detect some invasive species by their distinct patterns of greening and dormancy over an annual cycle based on hyperspectral data. Both applications require methods to quantify the non-green cellulosic fractions of plant tissues by remote sensing even in the presence of soil and green plant cover. We explore these methods and offer three case studies. The first concerns distinguishing surface litter from soil using the Cellulose Absorption Index (CAI), as applied to no-till farming practices where plant litter is left on the soil after harvest. The second involves using different band combinations to distinguish invasive saltcedar from agricultural and native riparian plants on the Lower Colorado River. The third illustrates the use of the CAI and NDVI in time-series analyses to distinguish between invasive buffelgrass and native plants in a desert environment in Arizona. Together the results show how hyperspectral imagery can be applied to

  8. Fire alters ecosystem carbon and nutrients but not plant nutrient stoichiometry or composition in tropical savanna.

    Science.gov (United States)

    Pellegrini, Adam F A; Hedin, Lars O; Staver, A Carla; Govender, Navashni

    2015-05-01

    Fire and nutrients interact to influence the global distribution and dynamics of the savanna biome, but the results of these interactions are both complex and poorly known. A critical but unresolved question is whether short-term losses of carbon and nutrients caused by fire can trigger long-term and potentially compensatory responses in the nutrient stoichiometry of plants, or in the abundance of dinitrogen-fixing trees. There is disagreement in the literature about the potential role of fire on savanna nutrients, and, in turn, on plant stoichiometry and composition. A major limitation has been the lack of fire manipulations over time scales sufficiently long for these interactions to emerge. We use a 58-year, replicated, large-scale, fire manipulation experiment in Kruger National Park (South Africa) in savanna to quantify the effect of fire on (1) distributions of carbon, nitrogen, and phosphorus at the ecosystem scale; (2) carbon: nitrogen: phosphorus stoichiometry of above- and belowground tissues of plant species; and (3) abundance of plant functional groups including nitrogen fixers. Our results show dramatic effects of fire on the relative distribution of nutrients in soils, but that individual plant stoichiometry and plant community composition remained unexpectedly resilient. Moreover, measures of nutrients and carbon stable isotopes allowed us to discount the role of tree cover change in favor of the turnover of herbaceous biomass as the primary mechanism that mediates a transition from low to high 'soil carbon and nutrients in the absence of fire. We conclude that, in contrast to extra-tropical grasslands or closed-canopy forests, vegetation in the savanna biome may be uniquely adapted to nutrient losses caused by recurring fire.

  9. The role of microorganisms and plants at different stages of ecosystem development for soil formation

    Directory of Open Access Journals (Sweden)

    S. Schulz

    2013-02-01

    Full Text Available Soil formation is the result of a complex network of biological as well as chemical and physical processes. Mainly the role of soil microbes is of high interest in this respect, as they are responsible for most transformations and drive the development of stable and labile carbon and nutrient pools in soil, which facilitate the basis for the subsequent establishment of plant communities. Glacier forefields, which provide a chronosequence of soils of different age due to the continuous retreat of the ice layer as a consequence of the increasing annual temperature since the last centuries, are a nice play ground to study the interaction of bacteria, fungi and archaea with their abiotic environment at different stages of soil formation. In this review we give insights into the role of microbes for soil development on the basis of investigations which have been performed at the Damma glacier in Switzerland in the frame of two international network projects Big Link (http://www.cces.ethz.ch/projects/clench/BigLink/ and DFG SFB/TRR 38 (ecosystem/" target="_blank">http://www.tu-cottbus.de/ecosystem/. The review focusses on the microbiology of three major steps of soil formation including weathering of the parental material, the development of basic nutrient cycles, the formation of soil crusts and biofilms as initial microbial network structures and the occurrence of plants respectively the setup of plant communities.

  10. Restoration of Ecosystems Destroyed by the Fly Ash Dump Using Different Plant Species

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    Florica Morariu

    2013-10-01

    Full Text Available The leguminous plants was studied at experimental variants on fly ash dump: sown species of Onobrichys viciifolia and invasive colonies of Bird's-foot Trefoil (Lotus corniculatus, and yellow sweet (Melilotus officinalis. Six experimental variants were studied in three replicates each: untreated fly ash, fly ash amended with unmodified/modified volcanic rock and fly ash treated with unmodified/modified volcanic rock (indigenous volcanic tuff mixed with organic fertilizer, anaerobically stabilized municipal sludge type. The characteristics of topsoil was assessed in toxic metals Cr, Cu, Pb, Ni content and the characteristics of plants was assessed in terms: height, shoot and roots dry weight, root and shoot ratio, root length density, the aspect plant and competitive ability of this species to dominate in sown habitat. Invasive plants (Lotus corniculatus and Melilotus officinalis have colonized up to 38 - 43 % and max 5 % respectively, treated experimental variants fly ash with organic fertilizer mixed with unmodified/modified volcanic tuff. The proposed strategy with sown leguminous species led to improved conditions for installation of more and resistant invasive species. Furthermore ecological restoration is increasing with effective fly ash dump stabilization.

  11. Building a better foundation: improving root-trait measurements to understand and model plant and ecosystem processes.

    Science.gov (United States)

    McCormack, M Luke; Guo, Dali; Iversen, Colleen M; Chen, Weile; Eissenstat, David M; Fernandez, Christopher W; Li, Le; Ma, Chengen; Ma, Zeqing; Poorter, Hendrik; Reich, Peter B; Zadworny, Marcin; Zanne, Amy

    2017-07-01

    Trait-based approaches provide a useful framework to investigate plant strategies for resource acquisition, growth, and competition, as well as plant impacts on ecosystem processes. Despite significant progress capturing trait variation within and among stems and leaves, identification of trait syndromes within fine-root systems and between fine roots and other plant organs is limited. Here we discuss three underappreciated areas where focused measurements of fine-root traits can make significant contributions to ecosystem science. These include assessment of spatiotemporal variation in fine-root traits, integration of mycorrhizal fungi into fine-root-trait frameworks, and the need for improved scaling of traits measured on individual roots to ecosystem-level processes. Progress in each of these areas is providing opportunities to revisit how below-ground processes are represented in terrestrial biosphere models. Targeted measurements of fine-root traits with clear linkages to ecosystem processes and plant responses to environmental change are strongly needed to reduce empirical and model uncertainties. Further identifying how and when suites of root and whole-plant traits are coordinated or decoupled will ultimately provide a powerful tool for modeling plant form and function at local and global scales. © 2017 The Authors. New Phytologist © 2017 New Phytologist Trust.

  12. Water content differences have stronger effects than plant functional groups on soil bacteria in a steppe ecosystem.

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    Ximei Zhang

    Full Text Available Many investigations across natural and artificial plant diversity gradients have reported that both soil physicochemical factors and plant community composition affect soil microbial communities. To test the effect of plant diversity loss on soil bacterial communities, we conducted a five-year plant functional group removal experiment in a steppe ecosystem in Inner Mongolia (China. We found that the number and composition type of plant functional groups had no effect on bacterial diversity and community composition, or on the relative abundance of major taxa. In contrast, bacterial community patterns were significantly structured by soil water content differences among plots. Our results support researches that suggest that water availability is the key factor structuring soil bacterial communities in this semi-arid ecosystem.

  13. Modelling of plant-soil carbon, nitrogen and phosphorus cycling in semi-natural terrestrial ecosystems

    Science.gov (United States)

    Davies, Jessica; Quinton, John; Rowe, Ed; Tipping, Ed

    2013-04-01

    In recent centuries pools and fluxes of C, N and P in natural and semi-natural UK ecosystems have been transformed by atmospheric pollution leading to: acidification; eutrophication of surface waters; loss of biodiversity; and increased greenhouse gas emissions. In addition, climate change now threatens to perturb these systems further. Understanding in this field is vital in determining the consequences of artificial nutrient enrichment and land use and climate change, and mitigating against their effects. The N14CP model has been recently developed to assess the temporal responses of soil C, N and P pools to nutrient enrichment in semi-natural ecosystems, and explore the connections between these nutrients. It is a dynamic, mechanistic model, driven by: climate; CO2, N (fixation and pollutant deposition), and P (weathering and atmospheric deposition) inputs; and plant cover type. It explicitly links C, N, and P in both plants and soils, using plant element stoichiometry as the primary constraint. Net primary production, and plant/soil element pools, are calculated over time, and output fluxes of dissolved organic and inorganic, and gaseous, forms of C, N, and P produced. Radiocarbon data are used to constrain Soil Organic Matter (SOM) turnover. The SOM is represented as three pools, undergoing first-order decomposition reactions with turn-over rates ranging from 2 to 1000 years. The N14CP modelling methodology is discussed and its calibration and verification using observations from 200 northern European sites presented. Whilst the primary period of interest with respect to nutrient enrichment is from the industrial revolution onwards, plant-soil C, N and P are simulated at these sites for a period spanning from the start of the Holocene (to provide a spin-up period) to the present day. Clearly, during this time span land cover and usage will have changed at these sites, and histories of these changes are used as an input to the model. The influence of these land

  14. Effect of an invasive plant and moonlight on rodent foraging behavior in a coastal dune ecosystem.

    Science.gov (United States)

    Johnson, Matthew D; De León, Yesenia L

    2015-01-01

    Understanding how invasive plants may alter predator avoidance behaviors is important for granivorous rodents because their foraging can trigger ripple effects in trophic webs. Previous research has shown that European beach grass Ammophila arenaria, an invasive species in coastal California, affects the predation of other seeds by the rodents Microtus californicus, Peromyscus maniculatus, and Reithrodontomys megalotis. This may be due to lower perceived predation risk by rodents foraging in close proximity to the cover provided by Ammophila, but this mechanism has not yet been tested. We examined the perceived predation risk of rodents by measuring the 'giving up density' of food left behind in experimental patches of food in areas with and without abundant cover from Ammophila and under varying amount of moonlight. We found strong evidence that giving up density was lower in the thick uniform vegetation on Ammophila-dominated habitat than it was in the more sparsely and diversely vegetated restored habitat. There was also evidence that moonlight affected giving up density and that it mediated the effects of habitat, although with our design we were unable to distinguish the effects of lunar illumination and moon phase. Our findings illustrate that foraging rodents, well known to be risk-averse during moonlit nights, are also affected by the presence of an invasive plant. This result has implications for granivory and perhaps plant demography in invaded and restored coastal habitats. Future research in this system should work to unravel the complex trophic links formed by a non-native invasive plant (i.e., Ammophila) providing cover favored by native rodents, which likely forage on and potentially limit the recruitment of native and non-native plants, some of which have ecosystem consequences of their own.

  15. Effect of an invasive plant and moonlight on rodent foraging behavior in a coastal dune ecosystem.

    Directory of Open Access Journals (Sweden)

    Matthew D Johnson

    Full Text Available Understanding how invasive plants may alter predator avoidance behaviors is important for granivorous rodents because their foraging can trigger ripple effects in trophic webs. Previous research has shown that European beach grass Ammophila arenaria, an invasive species in coastal California, affects the predation of other seeds by the rodents Microtus californicus, Peromyscus maniculatus, and Reithrodontomys megalotis. This may be due to lower perceived predation risk by rodents foraging in close proximity to the cover provided by Ammophila, but this mechanism has not yet been tested. We examined the perceived predation risk of rodents by measuring the 'giving up density' of food left behind in experimental patches of food in areas with and without abundant cover from Ammophila and under varying amount of moonlight. We found strong evidence that giving up density was lower in the thick uniform vegetation on Ammophila-dominated habitat than it was in the more sparsely and diversely vegetated restored habitat. There was also evidence that moonlight affected giving up density and that it mediated the effects of habitat, although with our design we were unable to distinguish the effects of lunar illumination and moon phase. Our findings illustrate that foraging rodents, well known to be risk-averse during moonlit nights, are also affected by the presence of an invasive plant. This result has implications for granivory and perhaps plant demography in invaded and restored coastal habitats. Future research in this system should work to unravel the complex trophic links formed by a non-native invasive plant (i.e., Ammophila providing cover favored by native rodents, which likely forage on and potentially limit the recruitment of native and non-native plants, some of which have ecosystem consequences of their own.

  16. Genetic variation changes the interactions between the parasitic plant-ecosystem engineer Rhinanthus and its hosts.

    Science.gov (United States)

    Rowntree, Jennifer K; Cameron, Duncan D; Preziosi, Richard F

    2011-05-12

    Within-species genetic variation is a potent factor influencing between-species interactions and community-level structure. Species of the hemi-parasitic plant genus Rhinanthus act as ecosystem engineers, significantly altering above- and below-ground community structure in grasslands. Here, we show the importance of genotypic variation within a single host species (barley-Hordeum vulgare), and population-level variation among two species of parasite (Rhinanthus minor and Rhinanthus angustifolius) on the outcome of parasite infection for both partners. We measured host fitness (number of seeds) and calculated parasite virulence as the difference in seed set between infected and uninfected hosts (the inverse of host tolerance). Virulence was determined by genetic variation within the host species and among the parasite species, but R. angustifolius was consistently more virulent than R. minor. The most tolerant host had the lowest inherent fitness and did not gain a fitness advantage over other infected hosts. We measured parasite size as a proxy for transmission ability (ability to infect further hosts) and host resistance. Parasite size depended on the specific combination of host genotype, parasite species and parasite population, and no species was consistently larger. We demonstrate that the outcome of infection by Rhinanthus depends not only on the host species, but also on the underlying genetics of both host and parasite. Thus, genetic variations within host and parasite are probably essential components of the ecosystem-altering effects of Rhinanthus.

  17. Isolation and Characterization of Streptomycetes with-Plant Growth Promoting Potential from Mangrove Ecosystem.

    Science.gov (United States)

    Shrivastava, Pooja; Kumar, Rajesh; Yandigeri, Mahesh S; Malviya, Nityanand; Arora, Dilip K

    2015-01-01

    A total of 66 actinomycetes isolates were isolated from mangroves of Andhra Pradesh, India, using various enrichment techniques and pretreatments. The samples were collected from Coringa mangrove ecosystem and pre-treated by enrichment with CaCO3, sodium dodecyl sulphate and phenol, plated on the media supplemented with cycloheximide (50 mg/ml), nystatin (25 mg/ml) and nalidixic acid (50 mg/ml). The population count of actinomycetes fluctuated from 1.9 x 10(5) to 8.0 x 10(5)/g soil. Out of the isolated 66 actinomycetes, 8 isolates possessing plant growth promoting potential were further studied and characterized by physiological and biochemical traits and identified by 16S rRNA gene sequencing as different species of Streptomycetes genera.

  18. Microsatellite markers for Nuphar japonica (Nymphaeaceae), an aquatic plant in the agricultural ecosystem of Japan1

    Science.gov (United States)

    Kondo, Toshiaki; Watanabe, Sonoko; Shiga, Takashi; Isagi, Yuji

    2016-01-01

    Premise of the study: Nuphar species (Nymphaeaceae) are representative aquatic plants in irrigation ponds in Japanese agricultural ecosystems. We developed 15 polymorphic microsatellite markers for N. japonica and confirmed their utility for its close relatives N. oguraensis var. akiensis and N. ×saijoensis, which originated from natural hybridization between N. japonica and N. oguraensis. Methods and Results: Genetic variation was characterized in 15 polymorphic loci in three populations of N. japonica. The average number of alleles per locus was 3.47 (range = 2−9; n = 32), and the average expected heterozygosity per locus was 0.84 (range = 0.5–1.0); 11 loci were amplified in N. oguraensis var. akiensis and 15 in N. ×saijoensis. Conclusions: The polymorphic microsatellite markers developed in this study will be useful for investigating the levels of genetic diversity within remnant populations of Nuphar taxa and could provide a valuable tool for conservation genetics of these taxa. PMID:28101435

  19. Fine Scale ANUClimate Data for Ecosystem Modeling and Assessment of Plant Functional Types

    Science.gov (United States)

    Hutchinson, M. F.; Kesteven, J. L.; Xu, T.; Evans, B. J.; Togashi, H. F.; Stein, J. L.

    2015-12-01

    High resolution spatially extended values of climate variables play a central role in the assessment of climate and projected future climate in ecosystem modeling. The ground based meteorological network remains a key resource for deriving these spatially extended climate variables. We report on the production, and applications, of new anomaly based fine scale spatial interpolations of key climate variables at daily and monthly time scale, across the Australian continent. The methods incorporate several innovations that have significantly improved spatial predictive accuracy, as well as providing a platform for the incorporation of additional remotely sensed data. The interpolated climate data are supporting many continent-wide ecosystem modeling applications and are playing a key role in testing optimality hypotheses associated with plant functional types (PFTs). The accuracy, and robustness to data error, of anomaly-based interpolation has been enhanced by incorporating physical process aspects of the different climate variables and employing robust statistical methods implemented in the ANUSPLIN package. New regression procedures have also been developed to estimate "background" monthly climate normals from all stations with minimal records to substantially increase the density of supporting spatial networks. Monthly mean temperature interpolation has been enhanced by incorporating process based coastal effects that have reduced predictive error by around 10%. Overall errors in interpolated monthly temperature fields are around 25% less than errors reported by an earlier study. For monthly and daily precipitation, a new anomaly structure has been devised to take account of the skewness in precipitation data and the large proportion of zero values that present significant challenges to standard interpolation methods. The many applications include continent-wide Gross Primary Production modeling and assessing constraints on light and water use efficiency derived

  20. Dynamics of microbial communities during decomposition of litter from pioneering plants in initial soil ecosystems

    Directory of Open Access Journals (Sweden)

    J. Esperschütz

    2012-10-01

    Full Text Available In initial ecosystems concentrations of all macro- and micronutrients can be considered as extremely low. Plant litter therefore strongly influences the development of a degraders' food web and is an important source for C and N input into soil in such ecosystems. In the present study, a 13C litter decomposition field experiment was performed for 30 weeks in initial soils from a post-mining area near the city of Cottbus (Germany. Two of this regions' dominant but contrasting pioneering plant species (Lotus corniculatus L. and Calamagrostis epigejos L. were chosen to investigate the effects of litter quality on the litter decomposing microbial food web in initially nutrient-poor substrates. The results clearly indicate the importance of litter quality, mainly the amount of N stored in the litter material and its bioavailability for the degradation process and the development of microbial communities in the detritusphere and bulk soil. Whereas the degradation process of the L. corniculatus litter which had a low C/N ratio was fast and most pronounced changes in the microbial community structure were observed 1–4 weeks after litter addition, the degradation of the C. epigejos litter material was slow and microbial community changes mainly occurred at between 4 and 30 weeks after litter addition to the soil. However for both litter materials a clear indication for the importance of fungi for the degradation process was observed both on the abundance level as well as on the level of 13C incorporation (activity.

  1. Responses of plant community composition and biomass production to warming and nitrogen deposition in a temperate meadow ecosystem.

    Science.gov (United States)

    Zhang, Tao; Guo, Rui; Gao, Song; Guo, Jixun; Sun, Wei

    2015-01-01

    Climate change has profound influences on plant community composition and ecosystem functions. However, its effects on plant community composition and biomass production are not well understood. A four-year field experiment was conducted to examine the effects of warming, nitrogen (N) addition, and their interactions on plant community composition and biomass production in a temperate meadow ecosystem in northeast China. Experimental warming had no significant effect on plant species richness, evenness, and diversity, while N addition highly reduced the species richness and diversity. Warming tended to reduce the importance value of graminoid species but increased the value of forbs, while N addition had the opposite effect. Warming tended to increase the belowground biomass, but had an opposite tendency to decrease the aboveground biomass. The influences of warming on aboveground production were dependent upon precipitation. Experimental warming had little effect on aboveground biomass in the years with higher precipitation, but significantly suppressed aboveground biomass in dry years. Our results suggest that warming had indirect effects on plant production via its effect on the water availability. Nitrogen addition significantly increased above- and below-ground production, suggesting that N is one of the most important limiting factors determining plant productivity in the studied meadow steppe. Significant interactive effects of warming plus N addition on belowground biomass were also detected. Our observations revealed that environmental changes (warming and N deposition) play significant roles in regulating plant community composition and biomass production in temperate meadow steppe ecosystem in northeast China.

  2. Use of Plant Hydraulic Theory to Predict Ecosystem Fluxes Across Mountainous Gradients in Environmental Controls and Insect Disturbances

    Science.gov (United States)

    Ewers, B. E.; Pendall, E.; Reed, D. E.; Barnard, H. R.; Whitehouse, F.; Frank, J. M.; Massman, W. J.; Brooks, P. D.; Biederman, J. A.; Harpold, A. A.; Naithani, K. J.; Mitra, B.; Mackay, D. S.; Norton, U.; Borkhuu, B.

    2011-12-01

    While mountainous areas are critical for providing numerous ecosystem benefits at the regional scale, the strong gradients in environmental controls make predictions difficult. A key part of the problem is quantifying and predicting the feedback between mountain gradients and plant function which then controls ecosystem cycling. The emerging theory of plant hydraulics provides a rigorous yet simple platform from which to generate testable hypotheses and predictions of ecosystem pools and fluxes. Plant hydraulic theory predicts that plant controls over carbon, water, energy and nutrient fluxes can be derived from the limitation of plant water transport from the soil through xylem and out of stomata. In addition, the limit to plant water transport can be predicted by combining plant structure (e.g. xylem diameters or root-to-shoot ratios) and plant function (response of stomatal conductance to vapor pressure deficit or root vulnerability to cavitation). We evaluate the predictions of the plant hydraulic theory by testing it against data from a mountain gradient encompassing sagebrush steppe through subalpine forests (2700 to 3400 m). We further test the theory by predicting the carbon, water and nutrient exchanges from several coniferous trees in the same gradient that are dying from xylem dysfunction caused by blue-stain fungi carried by bark beetles. The common theme of both of these data sets is a change in water limitation caused by either changing precipitation along the mountainous gradient or lack of access to soil water from xylem-occluding fungi. Across all of the data sets which range in scale from individual plants to hillslopes, the data fit the predictions of plant hydraulic theory. Namely, there was a proportional tradeoff between the reference canopy stomatal conductance to water vapor and the sensitivity of that conductance to vapor pressure deficit that quantitatively fits the predictions of plant hydraulic theory. Incorporating this result into

  3. Can plant phloem properties affect the link between ecosystem assimilation and respiration?

    Science.gov (United States)

    Mencuccini, M.; Hölttä, T.; Sevanto, S.; Nikinmaa, E.

    2012-04-01

    Phloem transport of carbohydrates in plants under field conditions is currently not well understood. This is largely the result of the lack of techniques suitable for measuring phloem physiological properties continuously under field conditions. This lack of knowledge is currently hampering our efforts to link ecosystem-level processes of carbon fixation, allocation and use, especially belowground. On theoretical grounds, the properties of the transport pathway from canopy to roots must be important in affecting the link between carbon assimilation and respiration, but it is unclear whether their effect is partially or entirely masked by processes occurring in other parts of the ecosystem. One can also predict the characteristic time scales over which these effects should occur and, as consequence, predict whether the transfer of turgor and osmotic signals from the site of carbon assimilation to the sites of carbon use are likely to control respiration. We will present two sources of evidence suggesting that the properties of the phloem transport system may affect processes that are dependent on the supply of carbon substrate, such as root or soil respiration. Firstly, we will summarize the results of a literature survey on soil and ecosystem respiration where the speed of transfer of photosynthetic sugars from the plant canopy to the soil surface was determined. Estimates of the transfer speed could be grouped according to whether the study employed isotopic or canopy soil flux-based techniques. These two groups provided very different estimates of transfer times likely because transport of sucrose molecules, and pressure-concentration waves, in phloem differed. Secondly, we will argue that simultaneous measurements of bark and xylem diameters provide a novel tool to determine the continuous variations of phloem turgor in vivo in the field. We will present a model that interprets these changes in xylem and live bark diameters and present data testing the model

  4. Model development and calibration for investigating climate, soil, and plant physiological controls on desert ecosystems

    Science.gov (United States)

    Ng, G. C.; Bedford, D.; Miller, D. M.

    2011-12-01

    Arid ecosystems have adapted to cope with extreme temperatures and unreliable moisture inputs. Understanding desert vegetation dynamics through seasonal to inter-annual meteorological variability is important for assessing how further intensification of the hydrological system under climate change may impact desert ecosystems. Furthermore, due to world-wide problems with desertification, proper ecological characterization of deserts, which already cover a fifth of the world's land surface, is increasingly critical for monitoring global-scale ecology. We present a model-based study that examines spatio-temporal dynamics of desert vegetation in a research watershed located in the Mojave Desert. Moving from the basin floor to higher elevations, the study area covers a range of meteorological and soil conditions, allowing us to explore how various climate, soil, and plant physiological factors interact to affect desert ecosystems. The first stage of this work entails developing a model appropriate for simulating desert ecological systems. NCAR's CLM-CN model fully couples dynamics within the soil-vegetation-atmosphere continuum. It includes parameterizations for diverse vegetation types, making it a flexible and accessible tool for ecohydrological studies. The dominant plant-type in our study area is Larrea tridentata, a shrub abundantly found in deserts of North and South America. We find that the current CLM-CN sub-model for (semi-)arid region shrubs may not be suitable for the extreme conditions found in parts of the study area. Model modifications representing various adaptations of drought-resistant Larrea are crucial for properly simulating vegetation growth. Changes to CLM's soil hydraulic property functions are also needed to represent gravelly soils typical of the region. After developing a suitable parameterization for desert shrubs and soils, we calibrate the model to soil moisture and vegetation measurements in the study area. This includes soil moisture

  5. Plant carbon-nutrient interactions control CO{sub 2} exchange in Alaskan wet sedge tundra ecosystems

    Energy Technology Data Exchange (ETDEWEB)

    Johnson, L.C.; Shaver, G.R.; Cades, D.H.; Rastetter, E.; Nadelhoffer, K.; Giblin, A.; Laundre, J.; Stanley, A.

    2000-02-01

    The authors explored the long-term (8-yr) effects of separate field manipulations of temperature and nutrient availability on carbon balance in wet sedge tundra near the Arctic Long Term Ecological Research (LTER) site at Toolik Lake, Alaska. Their goals were (1) to assess the relative importance of chronic warming (with field greenhouses) and increased N and P availability (by fertilization) in controlling gross ecosystem photosynthesis, ecosystem respiration, and ultimately ecosystem C balance; and (2) to attempt to partition ecosystem responses to these treatments between plant and soil contributions. The authors present results of the effects of these manipulations on whole-system CO{sub 2} exchange over seasonal and duel cycles, and on nonrhizosphere soil microbial respiration using in situ soil incubations.

  6. Transient Social–Ecological Stability: the Effects of Invasive Species and Ecosystem Restoration on Nutrient Management Compromise in Lake Erie

    Directory of Open Access Journals (Sweden)

    Joseph D. Conroy

    2010-03-01

    Full Text Available Together, lake ecosystems and local human activity form complex social–ecological systems (SESs characterized by feedback loops and discontinuous change. Researchers in diverse fields have suggested that complex systems do not have single stable equilibria in the long term because of inevitable perturbation. During this study, we sought to address the general question of whether or not stable social–ecological equilibria exist in highly stressed and managed lacustrine systems. Using an integrated human–biophysical model, we investigated the impacts of a species invasion and ecosystem restoration on SES equilibrium, defined here as a compromise in phosphorus management among opposing stakeholders, in western Lake Erie. Our integrated model is composed of a calibrated ecological submodel representing Sandusky Bay, and a phosphorus management submodel that reflects the societal benefits and costs of phosphorus regulation. These two submodels together form a dynamic feedback loop that includes freshwater ecology, ecosystem services, and phosphorus management. We found that the invasion of dreissenid mussels decreased ecosystem resistance to eutrophication, necessitating increased phosphorus management to preserve ecosystem services and thus creating the potential for a shift in social–ecological equilibrium. Additionally, our results suggest that net benefits in the region following the invasion of dreissenids may never again reach the pre-invasion level if on-site phosphorus control is the sole management lever. Further demonstrating transient system stability, large-scale wetland restoration shifted points of management compromise to states characterized by less on-site phosphorus management and higher environmental quality, resulting in a significant increase in net benefits in the region. We conclude that lacustrine SESs are open and dynamic, and we recommend that future models of these systems emphasize site-specific perturbation over

  7. Effects of shading on photosynthesis, plant organic nitrogen uptake and root fungal colonization in a subarctic mire ecosystem

    DEFF Research Database (Denmark)

    Olsrud, Hanna Maria Kerstin; Michelsen, Anders

    2009-01-01

    deciduous and evergreen plant species decreased. Species dominance was correlated with uptake of 13C, i.e., the most productive species also took up the highest amount of glycine. The ecosystem exhibited a tendency towards lower colonization by ericoid mycorrhizal fungi and dark septate endophytes in hair...

  8. Ecological and spatial modeling : mapping ecosystems, landscape changes, and plant species distribution in Llanos del Orinoco, Venezuela

    NARCIS (Netherlands)

    Moreno, E.J.C.

    2007-01-01

    The transformation of Llanos del Orinoco, focused on the flooding savanna, is evaluated in terms of the change and replacement of the savanna ecosystem and the plant species distribution under a Landscape Ecological approach. This research is carried out at three spatial scales: sub-continental, reg

  9. The new flora of northeastern USA: quantifying introduced plant species occupancy in forest ecosystems.

    Science.gov (United States)

    Schulz, Bethany K; Gray, Andrew N

    2013-05-01

    Introduced plant species have significant negative impacts in many ecosystems and are found in many forests around the world. Some factors linked to the distribution of introduced species include fragmentation and disturbance, native species richness, and climatic and physical conditions of the landscape. However, there are few data sources that enable the assessment of introduced species occupancy in native plant communities over broad regions. Vegetation data from 1,302 forest inventory plots across 24 states in northeastern and mid-western USA were used to examine and compare the distribution of introduced species in relation to forest fragmentation across ecological provinces and forest types, and to examine correlations between native and introduced species richness. There were 305 introduced species recorded, and 66 % of all forested plots had at least one introduced species. Forest edge plots had higher constancy and occupancy of introduced species than intact forest plots, but the differences varied significantly among ecological provinces and, to a lesser degree, forest types. Weak but significant positive correlations between native and introduced species richness were observed most often in intact forests. Rosa multiflora was the most common introduced species recorded across the region, but Hieracium aurantiacum and Epipactus helleborine were dominant in some ecological provinces. Identifying regions and forest types with high and low constancies and occupation by introduced species can help target forest stands where management actions will be the most effective. Identifying seemingly benign introduced species that are more prevalent than realized will help focus attention on newly emerging invasives.

  10. Gene expression profiling--Opening the black box of plant ecosystem responses to global change

    Energy Technology Data Exchange (ETDEWEB)

    Leakey, A.D.B.; Ainsworth, E.A.; Bernard, S.M.; Markelz, R.J.C.; Ort, D.R.; Placella, S.A.P.; Rogers, A.; Smith, M.D.; Sudderth, E.A.; Weston, D.J.; Wullschleger, S.D.; Yuan, S.

    2009-11-01

    The use of genomic techniques to address ecological questions is emerging as the field of genomic ecology. Experimentation under environmentally realistic conditions to investigate the molecular response of plants to meaningful changes in growth conditions and ecological interactions is the defining feature of genomic ecology. Since the impact of global change factors on plant performance are mediated by direct effects at the molecular, biochemical and physiological scales, gene expression analysis promises important advances in understanding factors that have previously been consigned to the 'black box' of unknown mechanism. Various tools and approaches are available for assessing gene expression in model and non-model species as part of global change biology studies. Each approach has its own unique advantages and constraints. A first generation of genomic ecology studies in managed ecosystems and mesocosms have provided a testbed for the approach and have begun to reveal how the experimental design and data analysis of gene expression studies can be tailored for use in an ecological context.

  11. Very-High-Resolution Time-Lapse Photography for Plant and Ecosystems Research

    Directory of Open Access Journals (Sweden)

    Mary H. Nichols

    2013-09-01

    Full Text Available Premise of the study: Traditional photography is a compromise between image detail and area covered. We report a new method for creating time-lapse sequences of very-high-resolution photographs to produce zoomable images that facilitate observation across a range of spatial and temporal scales. Methods and Results: A robotic camera mount and software were used to capture images of the growth and movement in Brassica rapa every 15 s in the laboratory. The resultant time-lapse sequence (http://timemachine.gigapan.org/wiki/Plant_Growth captures growth detail such as circumnutation. A modified, solar-powered system was deployed at a remote field site in southern Arizona. Images were collected every 2 h over a 3-mo period to capture the response of vegetation to monsoon season rainfall (http://timemachine.gigapan.org/wiki/Arizona_Grasslands. Conclusions: A technique for observing time sequences of both individual plant and ecosystem response at a range of spatial scales is available for use in the laboratory and in the field.

  12. Effect of ecosystem retrogression on stable nitrogen and carbon isotopes of plants, soils and consumer organisms in boreal forest islands.

    Science.gov (United States)

    Hyodo, Fujio; Wardle, David A

    2009-07-01

    In the prolonged absence of catastrophic disturbance, ecosystem retrogression occurs, and this involves increased nutrient limitation, and reduced aboveground and belowground ecosystem processes rates. Little is known about how the nitrogen and carbon stable isotope ratios (delta(15)N and delta(13)C) of plants, soils and consumer organisms respond to retrogression in boreal forests. We investigated a 5000 year chronosequence of forested islands in the boreal zone of northern Sweden, for which the time since lightning-induced wildfire increases with decreasing island size, leading to ecosystem retrogression. For this system, tissue delta(15)N of three abundant plant species (Betula pubescens, Vaccinium myrtillus and Pleurozium schreberi) and humus all increased as retrogression proceeded. This is probably due to enhanced ecosystem inputs of N by biological fixation, and greater dependency of the plants on organic N during retrogression. The delta(13)C of B. pubescens and plant-derived humus also increased during retrogression, probably through nutrient limitation increasing plant physiological stress. Unlike the plants, delta(15)N of invertebrates (lycosid spiders and ants) did not increase during retrogression, probably because of their partial dependence on aquatic-derived prey that had a variable delta(15)N signature. The delta(13)C of the invertebrates increased as retrogression proceeded and converged towards that of an aquatic prey source (chironomid flies), suggesting increased dependence on aquatic-derived prey during retrogression. These results show that measurement of delta(15)N and delta(13)C of plants, soils, and consumers across the same environmental gradient can provide insights into environmental factors that drive both the aboveground and belowground subsystems, as well as the linkages between them.

  13. Effects of fire and herbivory on the stability of savanna ecosystems

    NARCIS (Netherlands)

    van Langevelde, F; van de Vijver, CADM; Kumar, L; van de Koppel, J; de Ridder, N; van Andel, J; Skidmore, AK; Hearne, JW; Stroosnijder, L; Bond, WJ; Prins, HHT; Rietkerk, M; Vijver, Claudius A.D.M. van de; Skidmore, Andrew K.; Hearne, John W.; Bond, William J.; Lauenroth, W.K.

    2003-01-01

    Savanna ecosystems are characterized by the co-occurrence of trees and grasses. In this paper, we argue that the balance between trees and grasses is, to a large extent,determined by the indirect interactive effects of herbivory and fire. These effects are based on the positive feedback between fuel

  14. Controls on the D/H ratios of plant leaf waxes in an arid ecosystem

    Science.gov (United States)

    Feakins, Sarah J.; Sessions, Alex L.

    2010-04-01

    The extent to which leaf water D-enrichment (transpiration) and soil water D-enrichment (evaporation) affect the D/H ratio of plant leaf waxes remains a contentious issue, with important implications for paleohydrologic reconstructions. In this study we measure δD values of precipitation ( δD p), groundwater ( δD gw), plant xylem water ( δD xw) and leaf water ( δD lw) to understand their impact on the δD values of plant leaf wax n-alkanes ( δD wax) in an arid ecosystem. Our survey includes multiple species at four sites across an aridity gradient (80-30% relative humidity) in southern California. We find that many species take up groundwater or precipitation without significant fractionation. D-enriched soil water is a minor source even in species known to perform and utilize waters from hydraulic lift, such as Larrea tridentata (+10‰). Measurements of leaf water isotopic composition demonstrate that transpiration is an important mechanism for D-enrichment of leaf waters (+74 ± 20‰, 1 σ), resulting in the smallest net fractionation yet reported between source water and leaf waxes ( L. tridentata -41‰; multi-species mean value is -94 ± 21‰, 1 σ). We find little change in leaf water D-enrichment or net fractionation across the climatic gradient sampled by our study, suggesting that a net fractionation of ca. -90‰ may be appropriate for paleohydrologic reconstructions in semi-arid to arid environments. Large interspecies offsets in net fractionations (1 σ = 21‰) are potentially troublesome, given the observed floristic diversity and the likelihood of species assemblage changes with climate shifts.

  15. Long-term efficiency and stability of wetlands for treating wastewater of a lead/zinc mine and the concurrent ecosystem development

    Energy Technology Data Exchange (ETDEWEB)

    Yang, B. [School of Life Sciences, and State Key Laboratory of Biocontrol, Sun Yat-Sen (Zhongshan) University, Guangzhou 510275 (China); Lan, C.Y. [School of Life Sciences, and State Key Laboratory of Biocontrol, Sun Yat-Sen (Zhongshan) University, Guangzhou 510275 (China); Yang, C.S. [School of Life Sciences, and State Key Laboratory of Biocontrol, Sun Yat-Sen (Zhongshan) University, Guangzhou 510275 (China); College of Golf, Shenzhen University, Shenzhen 518060 (China); Liao, W.B. [School of Life Sciences, and State Key Laboratory of Biocontrol, Sun Yat-Sen (Zhongshan) University, Guangzhou 510275 (China); Chang, H. [School of Life Sciences, and State Key Laboratory of Biocontrol, Sun Yat-Sen (Zhongshan) University, Guangzhou 510275 (China); Shu, W.S. [School of Life Sciences, and State Key Laboratory of Biocontrol, Sun Yat-Sen (Zhongshan) University, Guangzhou 510275 (China)]. E-mail: ls53@zsu.edu.cn

    2006-10-15

    A constructed wetland system in Guangdong Province, South of China has been used for treating Pb/Zn mine discharge since 1985. The performance in the purification of the mine discharge and the concurrent ecosystem development within the system during the period of 1985-2000 has been studied. The untreated wastewater contained rather high concentrations of cadmium (Cd) (0.05 mg L{sup -1}), lead (Pb) (11.5 mg L{sup -1}), and zinc (Zn) (14.5 mg L{sup -1}), which greatly exceed the upper limits for industrial wastewater discharge in China. The constructed wetland system effectively removed Cd by 94.00%, Pb by 99.04%, Zn by 97.30%, and total suspended solids (TSS) by 98.95% from the mine discharge over a long period (over 16 years) leading to significant improvement in water quality; it was also found that there were no significantly annual or monthly variations in pH values, As, Cd, Hg, Pb, and Zn concentrations in water collected from the outlet of the wetland. Moreover, diversity and abundance of living organisms, including protozoan, higher plants, terrestrial animals, and birds, increased gradually. The 16-year monitoring results showed a reciprocal relationship, at a certain extent, between restoration of the wetland ecosystem, in other words, the maturity of the wetland, and the long-term efficiency and stability on purifying heavy metal-contaminated wastewater. - Relationship between the maturity of a constructed wetland and the long-term efficiency and stability of purifying heavy metal-contaminated wastewater.

  16. Ecosystem-based assessment indices of restoration for Daya Bay near a nuclear power plant in South China.

    Science.gov (United States)

    Chen, Xiaoyan; Gao, Huiwang; Yao, Xiaohong; Fang, Hongda; Chen, Zhenhua; Xu, Zhanzhou

    2010-10-01

    China has adopted nuclear power generation as one of the strategic energy sources to resolve the dilemma between its ever-growing energy demand and the associated environmental issues. To achieve the latter, a systematic assessment of the state of the ecosystem near nuclear power plants and its restoration via ongoing recovery actions would be highly desirable and much needed. Current assessment methods are mostly based on the individual components of the ecosystem and the methods are therefore not integrated. In this paper, we report a set of system-based assessment indices to study the restoration of Daya Bay in Guangdong, China where a nuclear power plant has been in operation for 15 years. The results show that decades of intensive exploitation by the various coastal activities have pushed Daya Bay's ecosystem away from its baseline and its structure and functions are impaired; ecosystem restoration does not make up for the weakening of the ecological carrying capacity due to anthropogenic sea-use, nonetheless, the potential for recovery still exists. The case study suggests that the system-based indices can provide integrated information for ecosystem restoration assessment and management.

  17. Linking land-use intensification, plant communities, and ecosystem processes in lowland Bolivia

    NARCIS (Netherlands)

    Carreno Rocabado, I.G.

    2013-01-01

    Land-use intensification (LUI) is one of the main global drivers of biodiversity loss with negative impact on ecosystem processes and the services that societies derive from the ecosystems. The effect of LUI on ecosystem processes can be direct through changes in environmental conditions and indirec

  18. The effect of increased temperature and altered precipitation on plants in an arid ecosystem

    Science.gov (United States)

    Wertin, T. M.; Reed, S.; Belnap, J.

    2011-12-01

    Projected changes in climate are expected to strongly affect arid and semi-arid landscapes where plant communities are assumed to already experience high temperatures and low water availability. Here we investigated the effect of elevated temperature and altered precipitation regimes on plant physiology, community composition, phenology and growth on the Colorado Plateau. The ecosystem is dominated by the native perennial grasses Pleuraphis jamesii and Achnatherum hymenoides and the shrub Atriplex confertifolia and has well-formed biological soil crusts. The invasive annual grass Bromus tectorum is also present. In 2005, five blocks of four 2m by 2.5m plots were established, and within each block plots were randomly assigned to ambient or elevated temperature (soil surface temperature of +2°C above ambient) and ambient or elevated precipitation (1.5 mm precipitation pulses applied three times weekly during summer) in full-factorial. In 2009 the temperature treatment was increased to +4°C. Additionally, five new blocks were established with the plots randomly assigned ambient or elevated temperature (again, +2°C was used) and ambient or elevated precipitation (summertime large bi-weekly watering to counteract negative effects the lamps may have had on soil moisture) in full-factorial. Throughout 2010 and 2011 the phenological state of the dominate plant species was recorded weekly. At the end of May 2010 and 2011 biomass accumulation, reproductive output and vegetative cover were assessed. Additionally, diurnal foliar gas exchange, foliar fluorescence and xylem pressure potential were measured on the dominant plant species three times throughout the spring and summer of 2011. Elevated temperature had no effect on carbon fixation or foliar physiology of A. confertifolia or P. jamesii, though A. hymenoides carbon fixation was negatively affected by elevated temperature with the +4°C treatment causing a greater reduction in fixation than the +2°C treatment. The

  19. Nitrogen Uptake During Fall, Winter and Spring Differs Among Plant Functional Groups in a Subarctic Heath Ecosystem

    DEFF Research Database (Denmark)

    Larsen, Klaus Steenberg; Michelsen, Anders; Jonasson, Sven;

    2012-01-01

    Nitrogen (N) is a critical resource for plant growth in tundra ecosystems, and species differences in the timing of N uptake may be an important feature regulating community composition and ecosystem productivity. We added 15N-labelled glycine to a subarctic heath tundra dominated by dwarf shrubs...... to 37 ± 7% by April indicating significant microbial N turnover prior to spring thaw. Only the evergreen dwarf shrubs showed active 15N acquisition before early May indicating that they had the highest potential of all functional groups for acquiring nutrients that became available in early spring...

  20. Quantifying the importance of plant functional diversity for ecosystem functioning and resilience under scenarios of climate change (Invited)

    Science.gov (United States)

    Pavlick, R.; Drewry, D.; Kleidon, A.

    2013-12-01

    Dynamic Global Vegetation Models (DGVMs) typically employ only a small set of Plant Functional Types (PFTs) to represent the vast diversity of observed vegetation forms and functioning. There is growing evidence, however, that this abstraction may not adequately represent the observed variation in plant functional traits, which is thought to play an important role for many ecosystem functions and for ecosystem resilience to environmental change. The geographic distribution of PFTs in these models is also often based on empirical relationships between present-day climate and vegetation patterns. Projections of future climate change, however, point toward the possibility of novel regional climates, which could lead to no-analog vegetation compositions incompatible with the PFT paradigm. Here, we present results from the Jena Diversity-DGVM (JeDi-DGVM), a novel traits-based vegetation model, which simulates a large number of hypothetical plant growth strategies constrained by functional tradeoffs, thereby allowing for a more flexible temporal and spatial representation of the terrestrial biosphere. We run two sets of model experiments forced with the latest bias-corrected climate change scenarios from several different global climate models. In the first set, we simulate a diverse biosphere using a large number of plant growth strategies, allowing the modelled ecosystems to adapt through emergent changes in ecosystem composition. We then aggregate the surviving growth strategies from the first set of diverse simulations to a small number of biome-averaged growth strategies, recreating something akin to PFTs. We use this smaller set of PFT-like growth strategies to represent a sparse or low-diversity biosphere in the second set of model experiments. We quantify the importance of functional diversity by comparing key metrics of ecosystem functioning across the two sets of simulations. The results reveal the implications of using the common PFT vegetation modelling

  1. Trait-based representation of hydrological functional properties of plants in weather and ecosystem models

    Directory of Open Access Journals (Sweden)

    Ashley M. Matheny

    2017-02-01

    Full Text Available Land surface models and dynamic global vegetation models typically represent vegetation through coarse plant functional type groupings based on leaf form, phenology, and bioclimatic limits. Although these groupings were both feasible and functional for early model generations, in light of the pace at which our knowledge of functional ecology, ecosystem demographics, and vegetation-climate feedbacks has advanced and the ever growing demand for enhanced model performance, these groupings have become antiquated and are identified as a key source of model uncertainty. The newest wave of model development is centered on shifting the vegetation paradigm away from plant functional types (PFTs and towards flexible trait-based representations. These models seek to improve errors in ecosystem fluxes that result from information loss due to over-aggregation of dissimilar species into the same functional class. We advocate the importance of the inclusion of plant hydraulic trait representation within the new paradigm through a framework of the whole-plant hydraulic strategy. Plant hydraulic strategy is known to play a critical role in the regulation of stomatal conductance and thus transpiration and latent heat flux. It is typical that coexisting plants employ opposing hydraulic strategies, and therefore have disparate patterns of water acquisition and use. Hydraulic traits are deterministic of drought resilience, response to disturbance, and other demographic processes. The addition of plant hydraulic properties in models may not only improve the simulation of carbon and water fluxes but also vegetation population distributions.

  2. Bridging Multiple Lines Of Evidence To Quantify Plant Phenology And Assess Links To Dryland Ecosystem Function

    Science.gov (United States)

    Browning, D. M.; Tweedie, C. E.; Vivoni, E. R.; Maynard, J. J.; Karl, J.

    2015-12-01

    The clear and pressing need to reliably identify and predict shifts in plant phenology at landscape scales requires a critical link between mechanistic understanding of climate drivers and broad scale forecasts of plant responses to climate change. A multi-scale phenology study co-located with two eddy covariance towers was initiated on the Jornada Basin LTER in New Mexico in 2010 to bridge phenology patterns at the plant level with those representing aggregated signals at the landscape level. The study integrates phenology observations collected in the field along with those collected via remotely using imagery from phenocams, unmanned aerial vehicles (UAVs), and satellite sensors along with estimates of carbon flux. We applied the Breaks for Additive Seasonal and Trend (BFAST) time series algorithm to MODIS 250-m NDVI greenness index values to partition the NDVI signal into components representing the long-term trend, seasonal periodicity, and residuals and identified significant shifts in the NDVI signal (i.e., "breaks"). Previous work verified breaks representing significant deviations from the BFAST seasonal and trend models using field-estimated plant biomass collected between 2000 and 2014. We subsequently examine estimates of fractional cover by functional group derived from UAV images acquired 2010 through 2015. At a mixed grassland site, the BFAST algorithm detected four breaks in the trend model denoting significant increases in NDVI in May 2004, July 2006, and March 2010 and a significant decrease in May 2012. The 2004 and 2006 breaks corresponded to herbaceous vegetation responses to rainfall following prolonged periods of drought. The 2012 decrease in NDVI corresponded to the marked reduction of herbaceous biomass following an exceptionally dry period in late 2010-2011. Seasonal breaks representing changes in the timing and magnitude of NDVI identified in July 2006 and September 2008 coincide with rapid increases in production of annual species in

  3. Application of Bayesian Network modeling on the stability and toxicity of engineered nanomaterials in aquatic ecosystems

    CSIR Research Space (South Africa)

    Ondiaka, M

    2013-08-01

    Full Text Available The stability of engineered nanomaterials (ENMs) in the aquatic systems influences their eventual interactions with aquatic biota – and subsequently the observed toxic effects. Increasing data suggests that physicochemical properties of ENMs...

  4. Pulse-drought atop press-drought: unexpected plant responses and implications for dryland ecosystems

    Science.gov (United States)

    Hoover, David L; Duniway, Michael C.; Belnap, Jayne

    2015-01-01

    In drylands, climate change is predicted to cause chronic reductions in water availability (press-droughts) through reduced precipitation and increased temperatures as well as increase the frequency and intensity of short-term extreme droughts (pulse-droughts). These changes in precipitation patterns may have profound ecosystem effects, depending on the sensitivities of the dominant plant functional types (PFTs). Here we present the responses of four Colorado Plateau PFTs to an experimentally imposed, 4-year, press-drought during which a natural pulse-drought occurred. Our objectives were to (1) identify the drought sensitivities of the PFTs, (2) assess the additive effects of the press- and pulse-drought, and (3) examine the interactive effects of soils and drought. Our results revealed that the C3 grasses were the most sensitive PFT to drought, the C3shrubs were the most resistant, and the C4 grasses and shrubs had intermediate drought sensitivities. Although we expected the C3 grasses would have the greatest response to drought, the higher resistance of C3 shrubs relative to the C4 shrubs was contrary to our predictions based on the higher water use efficiency of C4 photosynthesis. Also, the additive effects of press- and pulse-droughts caused high morality in C3 grasses, which has large ecological and economic ramifications for this region. Furthermore, despite predictions based on the inverse texture hypothesis, we observed no interactive effects of soils with the drought treatment on cover or mortality. These results suggest that plant responses to droughts in drylands may differ from expectations and have large ecological effects if press- and pulse-droughts push species beyond physiological and mortality thresholds.

  5. Pulse-drought atop press-drought: unexpected plant responses and implications for dryland ecosystems.

    Science.gov (United States)

    Hoover, David L; Duniway, Michael C; Belnap, Jayne

    2015-12-01

    In drylands, climate change is predicted to cause chronic reductions in water availability (press-droughts) through reduced precipitation and increased temperatures as well as increase the frequency and intensity of short-term extreme droughts (pulse-droughts). These changes in precipitation patterns may have profound ecosystem effects, depending on the sensitivities of the dominant plant functional types (PFTs). Here we present the responses of four Colorado Plateau PFTs to an experimentally imposed, 4-year, press-drought during which a natural pulse-drought occurred. Our objectives were to (1) identify the drought sensitivities of the PFTs, (2) assess the additive effects of the press- and pulse-drought, and (3) examine the interactive effects of soils and drought. Our results revealed that the C3 grasses were the most sensitive PFT to drought, the C3 shrubs were the most resistant, and the C4 grasses and shrubs had intermediate drought sensitivities. Although we expected the C3 grasses would have the greatest response to drought, the higher resistance of C3 shrubs relative to the C4 shrubs was contrary to our predictions based on the higher water use efficiency of C4 photosynthesis. Also, the additive effects of press- and pulse-droughts caused high morality in C3 grasses, which has large ecological and economic ramifications for this region. Furthermore, despite predictions based on the inverse texture hypothesis, we observed no interactive effects of soils with the drought treatment on cover or mortality. These results suggest that plant responses to droughts in drylands may differ from expectations and have large ecological effects if press- and pulse-droughts push species beyond physiological and mortality thresholds.

  6. Systematic analysis of stability patterns in plant primary metabolism.

    Directory of Open Access Journals (Sweden)

    Dorothee Girbig

    Full Text Available Metabolic networks are characterized by complex interactions and regulatory mechanisms between many individual components. These interactions determine whether a steady state is stable to perturbations. Structural kinetic modeling (SKM is a framework to analyze the stability of metabolic steady states that allows the study of the system Jacobian without requiring detailed knowledge about individual rate equations. Stability criteria can be derived by generating a large number of structural kinetic models (SK-models with randomly sampled parameter sets and evaluating the resulting Jacobian matrices. Until now, SKM experiments applied univariate tests to detect the network components with the largest influence on stability. In this work, we present an extended SKM approach relying on supervised machine learning to detect patterns of enzyme-metabolite interactions that act together in an orchestrated manner to ensure stability. We demonstrate its application on a detailed SK-model of the Calvin-Benson cycle and connected pathways. The identified stability patterns are highly complex reflecting that changes in dynamic properties depend on concerted interactions between several network components. In total, we find more patterns that reliably ensure stability than patterns ensuring instability. This shows that the design of this system is strongly targeted towards maintaining stability. We also investigate the effect of allosteric regulators revealing that the tendency to stability is significantly increased by including experimentally determined regulatory mechanisms that have not yet been integrated into existing kinetic models.

  7. Inferring differential evolutionary processes of plant persistence traits in Northern Hemisphere Mediterranean fire-prone ecosystems

    Science.gov (United States)

    Pausas, J.G.; Keeley, J.E.; Verdu, M.

    2006-01-01

    1 Resprouting capacity (R) and propagule-persistence (P) are traits that are often considered to have evolved where there are predictable crown fires. Because several indicators suggest a stronger selective pressure for such traits in California than in the Mediterranean Basin, we hypothesize that plant species should have evolved to become R+ and P+ more frequently in California than in the Mediterranean Basin. 2 To test this hypothesis we studied the phylogenetic association between R and P states in both California and the Mediterranean Basin using published molecular phylogenies. 3 The results suggest that R and P evolved differently in the two regions. The occurrence of the states differs significantly between regions for trait P, but not for trait R. The different patterns (towards R+ and P+ in California and towards R+ and P- in the Mediterranean Basin) are reflected in the higher abundance and the wider taxonomic distribution of species with both persistence traits (R+P+ species) in California. 4 The differential acquisition of fire persistence mechanisms at the propagule level (P+) supports the idea that fire selective pressures has been higher in California than in the Mediterranean Basin. 5 Our comparative phylogenetic-informed analysis contributes to an understanding of the differential role of the Quaternary climate in determining fire persistence traits in different Mediterranean-type ecosystems and, thus, to the debate on the evolutionary convergence of traits. ?? 2006 British Ecological Society.

  8. Spatial organization of multiple plant species in arid ecosystems:linking patterns and processes

    Institute of Scientific and Technical Information of China (English)

    Amit; CHAKRABORTY; B.Larry; LI

    2010-01-01

    Spatial organization of multiple plant species that appears as a non-random distribution of vegetative patches is one of the mostly observed spatial patterns in arid ecosystems. Yet understanding of ecological processes allowing this spatial pattern to emerge through interspecific interactions is still lacking. With a proposed conceptual model involving interspecific trade-offs between species competitive ability and colonization ability, we have argued that within patch abundance dynamics regulated by the mechanisms of competition are strongly influenced by the between patches colonization dynamics that are maintained via this trade-offs and it holds a positive, intraspecific occupancy-abundance relationship, in which increased patch occupancy increases species density within inhabiting patches. In a constant environment, while local abundance dynamics approach toward a stable equilibrium point, a fixed spatial arrangement of species can be retained through this coupled dynamics. However, in fluctuating environments where existence of such stable equilibriums is highly uncertain, it may involve continuous transitions from one community state to another as species re-organized themselves over space through the rapid changes in local species abundances. While some of the inhabiting patches are destroyed exogenously or endogenously, or species responses to increasing environmental fluctuations vary increasingly with time, discontinuous transitions into an abrupt, irreversible state of the community dynamics may occur, as with this effect the inherent positive relationship between occupancy and abundance of species is no longer maintained.

  9. Comparisons of diazotrophic communities in native and agricultural desert ecosystems reveal plants as important drivers in diversity.

    Science.gov (United States)

    Köberl, Martina; Erlacher, Armin; Ramadan, Elshahat M; El-Arabi, Tarek F; Müller, Henry; Bragina, Anastasia; Berg, Gabriele

    2016-02-01

    Diazotrophs provide the only biological source of fixed atmospheric nitrogen in the biosphere. Although they are the key player for plant-available nitrogen, less is known about their diversity and potential importance in arid ecosystems. We investigated the nitrogenase gene diversity in native and agricultural desert soil as well as within root-associated microbiota of medicinal plants grown in Egypt through the combination of nifH-specific qPCR, fingerprints, amplicon pyrosequencing and fluorescence in situ hybridization-confocal laser scanning microscopy. Although the diazotrophic microbiota were characterized by generally high abundances and diversity, statistically significant differences were found between both soils, the different microhabitats, and between the investigated plants (Matricaria chamomilla L., Calendula officinalis L. and Solanum distichum Schumach. and Thonn.). We observed a considerable community shift from desert to agriculturally used soil that demonstrated a higher abundance and diversity in the agro-ecosystem. The endorhiza was characterized by lower abundances and only a subset of species when compared to the rhizosphere. While the microbiomes of the Asteraceae were similar and dominated by potential root-nodulating rhizobia acquired primarily from soil, the perennial S. distichum generally formed associations with free-living nitrogen fixers. These results underline the importance of diazotrophs in desert ecosystems and additionally identify plants as important drivers in functional gene pool diversity.

  10. Comparisons of diazotrophic communities in native and agricultural desert ecosystems reveal plants as important drivers in diversity

    Science.gov (United States)

    Köberl, Martina; Erlacher, Armin; Ramadan, Elshahat M.; El-Arabi, Tarek F.; Müller, Henry; Bragina, Anastasia; Berg, Gabriele

    2015-01-01

    Diazotrophs provide the only biological source of fixed atmospheric nitrogen in the biosphere. Although they are the key player for plant-available nitrogen, less is known about their diversity and potential importance in arid ecosystems. We investigated the nitrogenase gene diversity in native and agricultural desert soil as well as within root-associated microbiota of medicinal plants grown in Egypt through the combination of nifH-specific qPCR, fingerprints, amplicon pyrosequencing and fluorescence in situ hybridization–confocal laser scanning microscopy. Although the diazotrophic microbiota were characterized by generally high abundances and diversity, statistically significant differences were found between both soils, the different microhabitats, and between the investigated plants (Matricaria chamomilla L., Calendula officinalis L. and Solanum distichum Schumach. and Thonn.). We observed a considerable community shift from desert to agriculturally used soil that demonstrated a higher abundance and diversity in the agro-ecosystem. The endorhiza was characterized by lower abundances and only a subset of species when compared to the rhizosphere. While the microbiomes of the Asteraceae were similar and dominated by potential root-nodulating rhizobia acquired primarily from soil, the perennial S. distichum generally formed associations with free-living nitrogen fixers. These results underline the importance of diazotrophs in desert ecosystems and additionally identify plants as important drivers in functional gene pool diversity. PMID:26705571

  11. Integrating plant-microbe interactions to understand soil C stabilization with the MIcrobial-MIneral Carbon Stabilization model (MIMICS)

    Science.gov (United States)

    Grandy, Stuart; Wieder, Will; Kallenbach, Cynthia; Tiemann, Lisa

    2014-05-01

    If soil organic matter is predominantly microbial biomass, plant inputs that build biomass should also increase SOM. This seems obvious, but the implications fundamentally change how we think about the relationships between plants, microbes and SOM. Plant residues that build microbial biomass are typically characterized by low C/N ratios and high lignin contents. However, plants with high lignin contents and high C/N ratios are believed to increase SOM, an entrenched idea that still strongly motivates agricultural soil management practices. Here we use a combination of meta-analysis with a new microbial-explicit soil biogeochemistry model to explore the relationships between plant litter chemistry, microbial communities, and SOM stabilization in different soil types. We use the MIcrobial-MIneral Carbon Stabilization (MIMICS) model, newly built upon the Community Land Model (CLM) platform, to enhance our understanding of biology in earth system processes. The turnover of litter and SOM in MIMICS are governed by the activity of r- and k-selected microbial groups and temperature sensitive Michaelis-Menten kinetics. Plant and microbial residues are stabilized short-term by chemical recalcitrance or long-term by physical protection. Fast-turnover litter inputs increase SOM by >10% depending on temperature in clay soils, and it's only in sandy soils devoid of physical protection mechanisms that recalcitrant inputs build SOM. These results challenge centuries of lay knowledge as well as conventional ideas of SOM formation, but are they realistic? To test this, we conducted a meta-analysis of the relationships between the chemistry of plant liter inputs and SOM concentrations. We find globally that the highest SOM concentrations are associated with plant inputs containing low C/N ratios. These results are confirmed by individual tracer studies pointing to greater stabilization of low C/N ratio inputs, particularly in clay soils. Our model and meta-analysis results suggest

  12. Uptake of uranium by aquatic plants growing in fresh water ecosystem around uranium mill tailings pond at Jaduguda, India

    Energy Technology Data Exchange (ETDEWEB)

    Jha, V.N., E-mail: jhavn1971@gmail.com; Tripathi, R.M., E-mail: tripathirm@yahoo.com; Sethy, N.K., E-mail: sethybarc@rediffmail.com; Sahoo, S.K., E-mail: sksbarc@gmail.com

    2016-01-01

    Concentration of uranium was determined in aquatic plants and substrate (sediment or water) of fresh water ecosystem on and around uranium mill tailings pond at Jaduguda, India. Aquatic plant/substrate concentration ratios (CRs) of uranium were estimated for different sites on and around the uranium mill tailings disposal area. These sites include upstream and downstream side of surface water sources carrying the treated tailings effluent, a small pond inside tailings disposal area and residual water of this area. Three types of plant groups were investigated namely algae (filamentous and non-filamentous), other free floating & water submerged and sediment rooted plants. Wide variability in concentration ratio was observed for different groups of plants studied. The filamentous algae uranium concentration was significantly correlated with that of water (r = 0.86, p < 0.003). For sediment rooted plants significant correlation was found between uranium concentration in plant and the substrate (r = 0.88, p < 0.001). Both for other free floating species and sediment rooted plants, uranium concentration was significantly correlated with Mn, Fe, and Ni concentration of plants (p < 0.01). Filamentous algae, Jussiaea and Pistia owing to their high bioproductivity, biomass, uranium accumulation and concentration ratio can be useful for prospecting phytoremediation of stream carrying treated or untreated uranium mill tailings effluent. - Highlights: • Uranium mill tailings pond. • Jaduguda, India. • Fresh water plants. • Uranium uptake. • Relationship of uranium with stable elements.

  13. In vitro assembly of plant tubulin in the absence of microtubule-stabilizing reagents

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    The assembly of microtubules is essential for physiological functions of microtubules. Addition of microtubule-stabilizing reagents or microtubule "seeds" is usually necessary for plant tubulin assembly in vitro, which hinders the investigation of plant microtubule dynamics. In the present note, highly purified plant tubulins have been obtained from lily pollen, a non-microtubule-stabilizing reagent or microtubule "seed" system for plant tubulin assembly has been established and the analysis of plant tubulin assembly performed. Experiment results showed that purified tubulin polymerized in vitro, and a typical microtubule structure was observed with electron microscopy. The kinetics curve of tubulin assembly exhibited typical "parabola". The presence of taxol significantly altered the character of plant tubulin assembly, including that abnormal microtubules were assembled and the critical concentration for plant tubulin assembly was decreased exceedingly from 3 mg/mL in the absence of taxol to 0.043 mg/mL in the presence of taxol.

  14. Contrasting water use pattern of introduced and native plants in an alpine desert ecosystem, Northeast Qinghai–Tibet Plateau, China

    Energy Technology Data Exchange (ETDEWEB)

    Wu, Huawu, E-mail: wuhuawu416@163.com [State Key Laboratory of Earth Surface Processes and Resource Ecology, Beijing Normal University, Beijing 100875 (China); College of Resources Science and Technology, Beijing Normal University, Beijing 100875 (China); Li, Xiao-Yan, E-mail: xyli@bnu.edu.cn [State Key Laboratory of Earth Surface Processes and Resource Ecology, Beijing Normal University, Beijing 100875 (China); College of Resources Science and Technology, Beijing Normal University, Beijing 100875 (China); Jiang, Zhiyun; Chen, Huiying; Zhang, Cicheng; Xiao, Xiong [College of Resources Science and Technology, Beijing Normal University, Beijing 100875 (China)

    2016-01-15

    Plant water use patterns reflect the complex interactions between different functional types and environmental conditions in water-limited ecosystems. However, the mechanisms underlying the water use patterns of plants in the alpine desert of the Qinghai–Tibet Plateau remain poorly understood. This study investigated seasonal variations in the water sources of herbs (Carex moorcroftii, Astragalus adsurgens) and shrubs (Artemisia oxycephala, Hippophae rhamnoides) using stable oxygen-18 isotope methods. The results indicated that the native herbs (C. moorcroftii, A. adsurgens) and one of the shrubs (A. oxycephala) mainly relied on water from the shallow layer (0–30 cm) throughout the growing season, while the introduced shrub (H. rhamnoides) showed plasticity in switching between water from shallow and deep soil layers depending on soil water availability. All studied plants primarily depended on water from shallow soil layers early in the season. The differences of water use patterns between the introduced and native plants are closely linked with the range of active root zones when competing for water. Our findings will facilitate the mechanistic understanding of plant–soil–water relations in alpine desert ecosystems and provide information for screening introduced species for sand fixation. - Highlights: • Stable oxygen-18 in soil water experienced great evaporation enrichment. • H. rhamnoides experiences a flexible plasticity to switch between shallow and deep soil water. • Native plants mostly relied on shallow and middle soil water. • Water-use patterns by introduced-native plants are controlled by root characteristics.

  15. The Class of Stabilizing Nonlinear Plant Controller Pairs

    NARCIS (Netherlands)

    Paice, A.D.B.; Schaft, Arjan J. van der

    1996-01-01

    In this paper a general approach is taken to yield a characterization of the class of stable plant controller pairs which is a generalization of the Youla parameterization for linear systems. This is based on the idea of representing the input-output pairs of the plant and controller as elements of

  16. Ecosystem Engineering by Plants on Wave-Exposed Intertidal Flats Is Governed by Relationships between Effect and Response Traits.

    Directory of Open Access Journals (Sweden)

    Maike Heuner

    Full Text Available In hydrodynamically stressful environments, some species--known as ecosystem engineers--are able to modify the environment for their own benefit. Little is known however, about the interaction between functional plant traits and ecosystem engineering. We studied the responses of Scirpus tabernaemontani and Scirpus maritimus to wave impact in full-scale flume experiments. Stem density and biomass were used to predict the ecosystem engineering effect of wave attenuation. Also the drag force on plants, their bending angle after wave impact and the stem biomechanical properties were quantified as both responses of stress experienced and effects on ecosystem engineering. We analyzed lignin, cellulose, and silica contents as traits likely effecting stress resistance (avoidance, tolerance. Stem density and biomass were strong predictors for wave attenuation, S. maritimus showing a higher effect than S. tabernaemontani. The drag force and drag force per wet frontal area both differed significantly between the species at shallow water depths (20 cm. At greater depths (35 cm, drag forces and bending angles were significantly higher for S. maritimus than for S. tabernaemontani. However, they do not differ in drag force per wet frontal area due to the larger plant surface of S. maritimus. Stem resistance to breaking and stem flexibility were significantly higher in S. tabernaemontani, having a higher cellulose concentration and a larger cross-section in its basal stem parts. S. maritimus had clearly more lignin and silica contents in the basal stem parts than S. tabernaemontani. We concluded that the effect of biomass seems more relevant for the engineering effect of emergent macrophytes with leaves than species morphology: S. tabernaemontani has avoiding traits with minor effects on wave attenuation; S. maritimus has tolerating traits with larger effects. This implies that ecosystem engineering effects are directly linked with traits affecting species

  17. A New Digital Imaging and Analysis System for Plant and Ecosystem Phenological Studies

    Science.gov (United States)

    Ramirez, G.; Ramirez, G. A.; Vargas, S. A., Jr.; Luna, N. R.; Tweedie, C. E.

    2015-12-01

    Over the past decade, environmental scientists have increasingly used low-cost sensors and custom software to gather and analyze environmental data. Included in this trend has been the use of imagery from field-mounted static digital cameras. Published literature has highlighted the challenge scientists have encountered with poor and problematic camera performance and power consumption, limited data download and wireless communication options, general ruggedness of off the shelf camera solutions, and time consuming and hard-to-reproduce digital image analysis options. Data loggers and sensors are typically limited to data storage in situ (requiring manual downloading) and/or expensive data streaming options. Here we highlight the features and functionality of a newly invented camera/data logger system and coupled image analysis software suited to plant and ecosystem phenological studies (patent pending). The camera has resulted from several years of development and prototype testing supported by several grants funded by the US NSF. These inventions have several unique features and functionality and have been field tested in desert, arctic, and tropical rainforest ecosystems. The system can be used to acquire imagery/data from static and mobile platforms. Data is collected, preprocessed, and streamed to the cloud without the need of an external computer and can run for extended time periods. The camera module is capable of acquiring RGB, IR, and thermal (LWIR) data and storing it in a variety of formats including RAW. The system is full customizable with a wide variety of passive and smart sensors. The camera can be triggered by state conditions detected by sensors and/or select time intervals. The device includes USB, Wi-Fi, Bluetooth, serial, GSM, Ethernet, and Iridium connections and can be connected to commercial cloud servers such as Dropbox. The complementary image analysis software is compatible with all popular operating systems. Imagery can be viewed and

  18. Repression of fungal plant pathogens and fungal-related contaminants: Selected ecosystem services by soil fauna communities in agroecosystems

    Science.gov (United States)

    Meyer-Wolfarth, Friederike; Schrader, Stefan; Oldenburg, Elisabeth; Brunotte, Joachim; Weinert, Joachim

    2017-04-01

    In agroecosystems soil-borne fungal plant diseases are major yield-limiting factors which are difficult to control. Fungal plant pathogens, like Fusarium species, survive as a saprophyte in infected tissue like crop residues and endanger the health of the following crop by increasing the infection risk for specific plant diseases. In infected plant organs, these pathogens are able to produce mycotoxins. Mycotoxins like deoxynivalenol (DON) persist during storage, are heat resistant and of major concern for human and animal health after consumption of contaminated food and feed, respectively. Among fungivorous soil organisms, there are representatives of the soil fauna which are obviously antagonistic to a Fusarium infection and the contamination with mycotoxins. Specific members of the soil macro-, meso-, and microfauna provide a wide range of ecosystem services including the stimulation of decomposition processes which may result in the regulation of plant pathogens and the degradation of environmental contaminants. Investigations under laboratory conditions and in field were conducted to assess the functional linkage between soil faunal communities and plant pathogenic fungi (Fusarium culmorum). The aim was to examine if Fusarium biomass and the content of its mycotoxin DON decrease substantially in the presence of soil fauna (earthworms: Lumbricus terrestris, collembolans: Folsomia candida and nematodes: Aphelenchoides saprophilus) in a commercial cropping system managed with conservation tillage located in Northern Germany. The results of our investigations pointed out that the degradation performance of the introduced soil fauna must be considered as an important contribution to the biodegradation of fungal plant diseases and fungal-related contaminants. Different size classes within functional groups and the traits of keystone species appear to be significant for soil function and the provision of ecosystem services as in particular L. terrestris revealed to

  19. Can observed ecosystem responses to elevated CO2 and N fertilisation be explained by optimal plant C allocation?

    Science.gov (United States)

    Stocker, Benjamin; Prentice, I. Colin

    2016-04-01

    The degree to which nitrogen availability limits the terrestrial C sink under rising CO2 is a key uncertainty in carbon cycle and climate change projections. Results from ecosystem manipulation studies and meta-analyses suggest that plant C allocation to roots adjusts dynamically under varying degrees of nitrogen availability and other soil fertility parameters. In addition, the ratio of biomass production to GPP appears to decline under nutrient scarcity. This reflects increasing plant C export into the soil and to symbionts (Cex) with decreasing nutrient availability. Cex is consumed by an array of soil organisms and may imply an improvement of nutrient availability to the plant. These concepts are left unaccounted for in Earth system models. We present a model for the coupled cycles of C and N in grassland ecosystems to explore optimal plant C allocation under rising CO2 and its implications for the ecosystem C balance. The model follows a balanced growth approach, accounting for the trade-offs between leaf versus root growth and Cex in balancing C fixation and N uptake. We further model a plant-controlled rate of biological N fixation (BNF) by assuming that Cex is consumed by N2-fixing processes if the ratio of Nup:Cex falls below the inverse of the C cost of N2-fixation. The model is applied at two temperate grassland sites (SwissFACE and BioCON), subjected to factorial treatments of elevated CO2 (FACE) and N fertilization. Preliminary simulation results indicate initially increased N limitation, evident by increased relative allocation to roots and Cex. Depending on the initial state of N availability, this implies a varying degree of aboveground growth enhancement, generally consistent with observed responses. On a longer time scale, ecosystems are progressively released from N limitation due tighter N cycling. Allowing for plant-controlled BNF implies a quicker release from N limitation and an adjustment to more open N cycling. In both cases, optimal plant

  20. Genetic variation in a tropical tree species influences the associated epiphytic plant and invertebrate communities in a complex forest ecosystem.

    Science.gov (United States)

    Zytynska, Sharon E; Fay, Michael F; Penney, David; Preziosi, Richard F

    2011-05-12

    Genetic differences among tree species, their hybrids and within tree species are known to influence associated ecological communities and ecosystem processes in areas of limited species diversity. The extent to which this same phenomenon occurs based on genetic variation within a single tree species, in a diverse complex ecosystem such as a tropical forest, is unknown. The level of biodiversity and complexity of the ecosystem may reduce the impact of a single tree species on associated communities. We assessed the influence of within-species genetic variation in the tree Brosimum alicastrum (Moraceae) on associated epiphytic and invertebrate communities in a neotropical rainforest. We found a significant positive association between genetic distance of trees and community difference of the epiphytic plants growing on the tree, the invertebrates living among the leaf litter around the base of the tree, and the invertebrates found on the tree trunk. This means that the more genetically similar trees are host to more similar epiphyte and invertebrate communities. Our work has implications for whole ecosystem conservation management, since maintaining sufficient genetic diversity at the primary producer level will enhance species diversity of other plants and animals.

  1. Distribution of ephemeral plants and their significance in dune stabilization in Gurbantunggut Desert

    Institute of Scientific and Technical Information of China (English)

    WANGXueqin; JIANGJin; LEIJiaqiang; ZHANGWeimin; QIANYibing

    2003-01-01

    Based on systematically monitoring plants on dune ridges in the southern part of the Gurbantunggut Desert in 2002, this paper, from the angle of dune stabilization by vegetation,describes the temporal and spatial distribution patterns of ephemeral plants on isolated sand dunes,analyses the natural invasion processes of ephemeral plants on human-disturbed sand surface and expounds the importance of ephemeral plants in stabilizing sand dune surface. A total of 45 plant species were identified in the study area, 29 of which are ephemeral plants. Ephemeral plants sprouted in early April and completed their life-circle within about two months. Just as aeolian sand activities came to the strongest stage from April to June in desert regions of northern Xinjiang, the total coverage of trees, shrubs and herbs of long vegetational period on most dune ridges was less than 10%, while the mean coverage of ephemeral plants reached 13.9% in April, 40.2% in May and 14.1% in June. Therefore ephemeral plants acted as the major contributor to dune surface stabilization in the Gurbantunggut Desert.Investigations of vegetation restoration on engineering-disturbed dune surface show that ephemeral plants first recolonized the disturbed dune surface.

  2. Using a multi-trait approach to manipulate plant functional diversity in a biodiversity-ecosystem function experiment.

    Directory of Open Access Journals (Sweden)

    Conrad Schittko

    Full Text Available A frequent pattern emerging from biodiversity-ecosystem function studies is that functional group richness enhances ecosystem functions such as primary productivity. However, the manipulation of functional group richness goes along with major disadvantages like the transformation of functional trait data into categories or the exclusion of functional differences between organisms in the same group. In a mesocosm study we manipulated plant functional diversity based on the multi-trait Functional Diversity (FD-approach of Petchey and Gaston by using database data of seven functional traits and information on the origin of the species in terms of being native or exotic. Along a gradient ranging from low to high FD we planted 40 randomly selected eight-species mixtures under controlled conditions. We found a significant positive linear correlation of FD with aboveground productivity and a negative correlation with invasibility of the plant communities. Based on community-weighted mean calculations for each functional trait, we figured out that the traits N-fixation and species origin, i.e. being native or exotic, played the most important role for community productivity. Our results suggest that the identification of the impact of functional trait diversity and the relative contributions of relevant traits is essential for a mechanistic understanding of the role of biodiversity for ecosystem functions such as aboveground biomass production and resistance against invasion.

  3. Using a multi-trait approach to manipulate plant functional diversity in a biodiversity-ecosystem function experiment.

    Science.gov (United States)

    Schittko, Conrad; Hawa, Mahmoud; Wurst, Susanne

    2014-01-01

    A frequent pattern emerging from biodiversity-ecosystem function studies is that functional group richness enhances ecosystem functions such as primary productivity. However, the manipulation of functional group richness goes along with major disadvantages like the transformation of functional trait data into categories or the exclusion of functional differences between organisms in the same group. In a mesocosm study we manipulated plant functional diversity based on the multi-trait Functional Diversity (FD)-approach of Petchey and Gaston by using database data of seven functional traits and information on the origin of the species in terms of being native or exotic. Along a gradient ranging from low to high FD we planted 40 randomly selected eight-species mixtures under controlled conditions. We found a significant positive linear correlation of FD with aboveground productivity and a negative correlation with invasibility of the plant communities. Based on community-weighted mean calculations for each functional trait, we figured out that the traits N-fixation and species origin, i.e. being native or exotic, played the most important role for community productivity. Our results suggest that the identification of the impact of functional trait diversity and the relative contributions of relevant traits is essential for a mechanistic understanding of the role of biodiversity for ecosystem functions such as aboveground biomass production and resistance against invasion.

  4. Effects of litter removal on plant species diversity: a case study in tropical Eucalyptus forest ecosystems in South China

    Institute of Scientific and Technical Information of China (English)

    2003-01-01

    The removal of litterfall in the Eucalyptus plantations in south China affected the plant biodiversity in these ecosystems was found based on the field observation and lab analysis. The protection times of species diversity of three Eucalyptus communities were different (Community I with no protection, Community II with 7-year-protection, Community III with 35-year-protection). The total numbers of species in these communities (from Community I to II to III) are 1, 6, and 17, respectively. The results showed that the protection of litterfall from being taken out of the ecosystem is important and can increase plant species diversity. This study combined biomass data, the chemical and physical properties of the soil, and the diversity of microbes in the communities. It is concluded that the mechanism of the effects of litter removal on biodiversity includes three factors: removing the suitable habitat of microbe and animal, decreasing the soil nutrient, and changing the special habitat for the germination and growth of invading plants. These results should have important implications for managing these Eucalyptus forest ecosystems in South China.

  5. Antecedent Moisture and Biological Inertia as Predictors of Plant and Ecosystem Productivity in Arid and Semiarid Systems

    Science.gov (United States)

    Ogle, K.

    2011-12-01

    Many plant and ecosystem processes in arid and semiarid systems may be affected by antecedent environmental conditions (e.g., precipitation patterns, soil water availability, temperature) that integrate over past days, weeks, months, seasons, or years. However, the importance of such antecedent exogenous effects relative to conditions occurring at the time of the observed process is relatively unexplored. Even less is known about the potential importance of antecedent endogenous effects that describe the influence of past ecosystem states on the current ecosystem state; e.g., how is current ecosystem productivity related to past productivity patterns? We hypothesize that incorporation of antecedent exogenous and endogenous factors can improve our predictive understanding of many plant and ecosystem processes, especially in arid and semiarid ecosystems. Furthermore, the common approach to quantifying the effects of antecedent (exogenous) variables relies on arbitrary, deterministic definitions of antecedent variables that (1) may not accurately describe the role of antecedent conditions and (2) ignore uncertainty associated with applying deterministic definitions. In this study, we employ a stochastic framework for (1) computing the antecedent variables that estimates the relative importance of conditions experienced each time unit into the past, also providing insight into potential lag responses, and (2) estimating the effect of antecedent factors on the response variable of interest. We employ this approach to explore the potential roles of antecedent exogenous and endogenous influences in three settings that illustrate the: (1) importance of antecedent precipitation for net primary productivity in the shortgrass steppe in northern Colorado, (2) dependency of tree growth on antecedent precipitation and past growth states for pinyon growing in western Colorado, and (3) influence of antecedent soil water and prior root status on observed root growth in the Mojave

  6. Plant competition, facilitation, and other overstory-understory interactions in longleaf pine ecosystems.

    Energy Technology Data Exchange (ETDEWEB)

    Imm, Donald; Blake, John I

    2006-07-01

    The Longleaf Pine Ecosystem - Ecology, Silviculture, and Restoration. Shibu Jose, Eric J. Jokela, and Deborah L. Miller, (eds.) Springer Series on Environmental Management. Springer Science and Business Media publisher. Box 10.2 Pp 330-333. An insert on overstory-understory interactions in longleaf pine ecosystems.

  7. Aromatic plants play an important role in promoting soil biological activity related to nitrogen cycling in an orchard ecosystem.

    Science.gov (United States)

    Chen, Xinxin; Song, Beizhou; Yao, Yuncong; Wu, Hongying; Hu, Jinghui; Zhao, Lingling

    2014-02-15

    Aromatic plants can substantially improve the diversity and structure of arthropod communities, as well as reduce the number of herbivore pests and regulate the abundance of predators and parasitoids. However, it is not clear whether aromatic plants are also effective in improving soil quality by enhancing nutrient cycling. Here, field experiments are described involving intercropping with aromatic plants to investigate their effect on soil nitrogen (N) cycling in an orchard ecosystem. The results indicate that the soil organic nitrogen and available nitrogen contents increased significantly in soils intercropped with aromatic plants. Similarly, the activities of soil protease and urease increased, together with total microbial biomass involved in N cycling, including nitrifying bacteria, denitrifying bacteria and azotobacters, as well as the total numbers of bacteria and fungi. This suggests that aromatic plants improve soil N cycling and nutrient levels by enriching the soil in organic matter through the regulation of both the abundance and community structure of microorganisms, together with associated soil enzyme activity, in orchard ecosystems.

  8. Contrasting water use pattern of introduced and native plants in an alpine desert ecosystem, Northeast Qinghai-Tibet Plateau, China.

    Science.gov (United States)

    Wu, Huawu; Li, Xiao-Yan; Jiang, Zhiyun; Chen, Huiying; Zhang, Cicheng; Xiao, Xiong

    2016-01-15

    Plant water use patterns reflect the complex interactions between different functional types and environmental conditions in water-limited ecosystems. However, the mechanisms underlying the water use patterns of plants in the alpine desert of the Qinghai-Tibet Plateau remain poorly understood. This study investigated seasonal variations in the water sources of herbs (Carex moorcroftii, Astragalus adsurgens) and shrubs (Artemisia oxycephala, Hippophae rhamnoides) using stable oxygen-18 isotope methods. The results indicated that the native herbs (C. moorcroftii, A. adsurgens) and one of the shrubs (A. oxycephala) mainly relied on water from the shallow layer (0-30 cm) throughout the growing season, while the introduced shrub (H. rhamnoides) showed plasticity in switching between water from shallow and deep soil layers depending on soil water availability. All studied plants primarily depended on water from shallow soil layers early in the season. The differences of water use patterns between the introduced and native plants are closely linked with the range of active root zones when competing for water. Our findings will facilitate the mechanistic understanding of plant-soil-water relations in alpine desert ecosystems and provide information for screening introduced species for sand fixation.

  9. Genomic stability of Palmer amaranth plants derived by macro-vegetative propagation

    Science.gov (United States)

    Q-PCR (quantitative polymerase chain reaction) and random amplified polymorphic DNA (RAPD) were utilized to investigate genetic stability of Palmer amaranth cloned plants over 10 generations. Q-PCR analysis of DNA from parent Palmer amaranth plants was repeated and confidence levels for determining ...

  10. Competition between plant functional types in the Canadian Terrestrial Ecosystem Model (CTEM) v. 2.0

    Science.gov (United States)

    Melton, J. R.; Arora, V. K.

    2016-01-01

    The Canadian Terrestrial Ecosystem Model (CTEM) is the interactive vegetation component in the Earth system model of the Canadian Centre for Climate Modelling and Analysis. CTEM models land-atmosphere exchange of CO2 through the response of carbon in living vegetation, and dead litter and soil pools, to changes in weather and climate at timescales of days to centuries. Version 1.0 of CTEM uses prescribed fractional coverage of plant functional types (PFTs) although, in reality, vegetation cover continually adapts to changes in climate, atmospheric composition and anthropogenic forcing. Changes in the spatial distribution of vegetation occur on timescales of years to centuries as vegetation distributions inherently have inertia. Here, we present version 2.0 of CTEM, which includes a representation of competition between PFTs based on a modified version of the Lotka-Volterra (L-V) predator-prey equations. Our approach is used to dynamically simulate the fractional coverage of CTEM's seven natural, non-crop PFTs, which are then compared with available observation-based estimates. Results from CTEM v. 2.0 show the model is able to represent the broad spatial distributions of its seven PFTs at the global scale. However, differences remain between modelled and observation-based fractional coverage of PFTs since representing the multitude of plant species globally, with just seven non-crop PFTs, only captures the large-scale climatic controls on PFT distributions. As expected, PFTs that exist in climate niches are difficult to represent either due to the coarse spatial resolution of the model, and the corresponding driving climate, or the limited number of PFTs used. We also simulate the fractional coverage of PFTs using unmodified L-V equations to illustrate its limitations. The geographic and zonal distributions of primary terrestrial carbon pools and fluxes from the versions of CTEM that use prescribed and dynamically simulated fractional coverage of PFTs compare

  11. Competition between plant functional types in the Canadian Terrestrial Ecosystem Model (CTEM v. 2.0

    Directory of Open Access Journals (Sweden)

    J. R. Melton

    2015-06-01

    Full Text Available The Canadian Terrestrial Ecosystem Model (CTEM is the interactive vegetation component in the Earth system model of the Canadian Centre for Climate Modelling and Analysis. CTEM models land–atmosphere exchange of CO2 through the response of carbon in living vegetation, and dead litter and soil pools, to changes in weather and climate at timescales of days to centuries. Version 1.0 of CTEM uses prescribed fractional coverage of plant functional types (PFTs although, in reality, vegetation cover continually adapts to changes in climate, atmospheric composition, and anthropogenic forcing. Changes in the spatial distribution of vegetation occur on timescales of years to centuries as vegetation distributions inherently have inertia. Here, we present version 2.0 of CTEM which includes a representation of competition between PFTs based on a modified version of the Lotka–Volterra (L–V predator–prey equations. Our approach is used to dynamically simulate the fractional coverage of CTEM's seven natural, non-crop PFTs which are then compared with available observation-based estimates. Results from CTEM v. 2.0 show the model is able to represent the broad spatial distributions of its seven PFTs at the global scale. However, differences remain between modelled and observation-based fractional coverages of PFTs since representing the multitude of plant species globally, with just seven non-crop PFTs, only captures the large scale climatic controls on PFT distributions. As expected, PFTs that exist in climate niches are difficult to represent either due to the coarse spatial resolution of the model, and the corresponding driving climate, or the limited number of PFTs used. We also simulate the fractional coverages of PFTs using unmodified L–V equations to illustrate its limitations. The geographic and zonal distributions of primary terrestrial carbon pools and fluxes from the versions of CTEM that use prescribed and dynamically simulated fractional

  12. Physicochemical stability of lycopene-loaded emulsions stabilized by plant or dairy proteins

    NARCIS (Netherlands)

    Ho, Kacie; Schroen, C.G.P.H.; San Martín-González, M.F.; Berton-Carabin, C.C.

    2016-01-01

    Lycopene is a lipophilic bioactive compound that can be challenging to deliver in vivo. To mediate this, delivery strategies, such as protein-stabilized oil-in-water (O/W) emulsions, have been suggested to improve the physicochemical stability and bioavailability of lycopene. In this research, the e

  13. Physicochemical stability of lycopene-loaded emulsions stabilized by plant or dairy proteins

    NARCIS (Netherlands)

    Ho, Kacie; Schroen, C.G.P.H.; San Martín-González, M.F.; Berton-Carabin, C.C.

    2017-01-01

    Lycopene is a lipophilic bioactive compound that can be challenging to deliver in vivo. To mediate this, delivery strategies, such as protein-stabilized oil-in-water (O/W) emulsions, have been suggested to improve the physicochemical stability and bioavailability of lycopene. In this research, the

  14. DESIGN OF A NEW INTERPOLATED CONTROLLER FOR STABILIZATION OF A SET OF INTERPOLATED PLANTS

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    Stabilization of a plant with variable operating conditions was considered. The plant is assumed to lie in a set of interpolated models composed of all interpolations generated between certain sets of proper stable coprime factorizations of transfer functions of two representative models that are defined at two representative operating points. An interpolated controller that is linear interpolation of coprime factorizations of two stabilizing controllers for the two representative models is designed to stabilize this set of interpolated models. Design of such an interpolated controller was converted to a feasibility problem constrained by several LMIs and a BMI, and a two-step iteration algorithm was employed to solve it.

  15. Modeling the response of plants and ecosystems to CO{sub 2} and climate change. Final technical report, September 1, 1992--August 31, 1996

    Energy Technology Data Exchange (ETDEWEB)

    Reynolds, J.F.

    1998-04-10

    Objectives can be divided into those for plant modeling and those for ecosystem modeling and experimental work in support of both. The author worked in a variety of ecosystem types, including pine, arctic, desert, and grasslands. Plant modeling objectives are: (1) to construct generic models of leaf, canopy, and whole-plant response to elevated CO{sub 2} and climate change; (2) to validate predictions of whole-plant response against various field studies of elevated CO{sub 2} and climate change; (3) to use these models to test specific hypotheses and to make predictions about primary, secondary and tertiary effects of elevated CO{sub 2} and climate change on individual plants for conditions and time frames beyond those used to calibrate the model; and (4) to provide information to higher-level models, such as community models and ecosystem models. Ecosystem level modeling objectives are: (1) to incorporate models of plant responses to elevated CO{sub 2} into a generic ecosystem model in order to predict the direct and indirect effects of elevated CO{sub 2} and climate change on ecosystems; (2) to validate model predictions of total system-level response (including decomposition) against various ecosystem field studies of elevated CO{sub 2} and climate change; (3) to use the ecosystem model to test specific hypotheses and to make predictions about primary, secondary and tertiary effects of elevated CO{sub 2} and climate change on ecosystems for conditions and time frames beyond those used to calibrate the model; and (4) to use the ecosystem model to study effects of change in CO{sub 2} and climate at regional and global scales. Occasionally the author conducted some experimental work that was deemed important to the development of the models. This work was mainly physiological work that could be performed in the Duke University Phytotron, using existing facilities.

  16. Understanding fog-plant interactions at the ecosystem scale using atmospheric carbonyl sulfide

    Science.gov (United States)

    Campbell, J. E.; Whelan, M.; Stinecipher, J.; Zumkehr, A. L.; Berry, J. A.; Dawson, T. E.; Seibt, U.; Hilton, T. W.; Kulkarni, S.; Commane, R.; Angevine, W. M.; Lu, Y.; Herndon, S. C.; Zahniser, M. S.

    2015-12-01

    Ecosystem metabolism is thought to have powerful feedbacks with the climate system as well as direct impacts on individual taxa that rely on ecosystems for food, water, and shelter. Despite the importance of an ecosystem level understanding, climate change impacts on whole ecosystems remains highly uncertain. In particular, coastal fog-dominated regions are a blind spot for whole ecosystem measurements of the land-air-sea exchange of carbon, water, and energy. To address this critical knowledge gap, our inter-displicary team from the University of California's new Institute for the Study of Ecological Effects of Climate Impacts (ISEECI) has launched a next-generation monitoring program along a gradient of UC Natural Reserve System (NRS) sites. We leverage recent breakthroughs in atmospheric spectroscopy and mechanistic ecosystem models of carbonyl sulfide that provide an unprecedented opportunity to explore the sustainability of coastal systems. Here we present our next-generation monitoring and regional analysis across a North/South transect of UC-NRS sites that has the potential to provide a new window into fog-dominated ecosystems, both currently and under climate change scenarios.

  17. Shrub invasion decreases diversity and alters community stability in northern Chihuahuan Desert plant communities.

    Directory of Open Access Journals (Sweden)

    Selene Báez

    Full Text Available BACKGROUND: Global climate change is rapidly altering species range distributions and interactions within communities. As ranges expand, invading species change interactions in communities which may reduce stability, a mechanism known to affect biodiversity. In aridland ecosystems worldwide, the range of native shrubs is expanding as they invade and replace native grassland vegetation with significant consequences for biodiversity and ecosystem functioning. METHODOLOGY: We used two long-term data sets to determine the effects of shrub encroachment by Larrea tridentata on subdominant community composition and stability in formerly native perennial grassland dominated by Bouteloua eriopoda in New Mexico, USA. PRINCIPAL FINDINGS: Our results indicated that Larrea invasion decreased species richness during the last 100 years. We also found that over shorter temporal scales species-poor subdominant communities in areas invaded by Larrea were less stable (more variable in time compared to species rich communities in grass-dominated vegetation. Compositional stability increased as cover of Bouteloua increased and decreased as cover of Larrea increased. SIGNIFICANCE: Changes in community stability due to altered interspecific interactions may be one mechanism by which biodiversity declines in grasslands following shrub invasion. As global warming increases, shrub encroachment into native grasslands worldwide will continue to alter species interactions and community stability both of which may lead to a decline in biodiversity.

  18. Inferring resilience to fragmentation-induced changes in plant communities in a semi-arid Mediterranean ecosystem.

    Science.gov (United States)

    de Frutos, Ángel; Navarro, Teresa; Pueyo, Yolanda; Alados, Concepción L

    2015-01-01

    Predicting the capacity of ecosystems to absorb impacts from disturbance events (resilience), including land-use intensification and landscape fragmentation, is challenging in the face of global change. Little is known about the impacts of fragmentation on ecosystem functioning from a multi-dimensional perspective (multiple traits). This study used 58 500-m linear transects to quantify changes in the functional composition and resilience of vascular plant communities in response to an increase in landscape fragmentation in 18 natural scrubland fragments embedded within a matrix of abandoned crop fields in Cabo de Gata-Níjar Natural Park, Almería, Spain. Changes in functional community composition were measured using functional diversity indices (functional richness and functional dispersion) that were based on 12 plant traits. Resilience was evaluated using the functional redundancy and response diversity from the perspective of plant dispersal, which is important, particularly, in fragmented landscapes. Scrubland fragmentation was measured using the Integral Index of Connectivity (IIC). The functional richness of the plant communities was higher in the most fragmented scrubland. Conversely, the functional dispersion (i.e., spread) of trait values among species in the functional trait space was lower at the most fragmented sites; consequently, the ecological tolerance of the vegetation to scrubland fragmentation decreased. Classifying the plant species into four functional groups indicated that fragmentation favoured an increase in functional redundancy in the 'short basal annual forbs and perennial forbs' group, most of which are species adapted to degraded soils. An assessment based on the traits associated with plant dispersal indicated that the resilience of 'woody plants', an important component in the Mediterranean scrubland, and habitat fragmentation were negatively correlated; however, the correlation was positive in the 'short basal annual forbs and

  19. Plant trait-based models identify direct and indirect effects of climate change on bundles of grassland ecosystem services.

    Science.gov (United States)

    Lamarque, Pénélope; Lavorel, Sandra; Mouchet, Maud; Quétier, Fabien

    2014-09-23

    Land use and climate change are primary causes of changes in the supply of ecosystem services (ESs). Although the consequences of climate change on ecosystem properties and associated services are well documented, the cascading impacts of climate change on ESs through changes in land use are largely overlooked. We present a trait-based framework based on an empirical model to elucidate how climate change affects tradeoffs among ESs. Using alternative scenarios for mountain grasslands, we predicted how direct effects of climate change on ecosystems and indirect effects through farmers' adaptations are likely to affect ES bundles through changes in plant functional properties. ES supply was overall more sensitive to climate than to induced management change, and ES bundles remained stable across scenarios. These responses largely reflected the restricted extent of management change in this constrained system, which was incorporated when scaling up plot level climate and management effects on ecosystem properties to the entire landscape. The trait-based approach revealed how the combination of common driving traits and common responses to changed fertility determined interactions and tradeoffs among ESs.

  20. Ecosystem Development after Mangrove Wetland Creation: Plant-Soil Change across a 20-year Chronosequence

    Science.gov (United States)

    Mangrove wetland restoration and creation efforts are increasingly proposed as mechanisms to compensate for mangrove wetland loss. However, ecosystem development and functional equivalence in restored and created mangrove wetlands is poorly understood. We compared a 20-yr chrono...

  1. Uptake of uranium by aquatic plants growing in fresh water ecosystem around uranium mill tailings pond at Jaduguda, India.

    Science.gov (United States)

    Jha, V N; Tripathi, R M; Sethy, N K; Sahoo, S K

    2016-01-01

    Concentration of uranium was determined in aquatic plants and substrate (sediment or water) of fresh water ecosystem on and around uranium mill tailings pond at Jaduguda, India. Aquatic plant/substrate concentration ratios (CRs) of uranium were estimated for different sites on and around the uranium mill tailings disposal area. These sites include upstream and downstream side of surface water sources carrying the treated tailings effluent, a small pond inside tailings disposal area and residual water of this area. Three types of plant groups were investigated namely algae (filamentous and non-filamentous), other free floating & water submerged and sediment rooted plants. Wide variability in concentration ratio was observed for different groups of plants studied. The filamentous algae uranium concentration was significantly correlated with that of water (r=0.86, pplants significant correlation was found between uranium concentration in plant and the substrate (r=0.88, pplants, uranium concentration was significantly correlated with Mn, Fe, and Ni concentration of plants (p<0.01). Filamentous algae, Jussiaea and Pistia owing to their high bioproductivity, biomass, uranium accumulation and concentration ratio can be useful for prospecting phytoremediation of stream carrying treated or untreated uranium mill tailings effluent.

  2. Assessing and monitoring impacts of genetically modified plants on agro-ecosystems: the approach of AMIGA project

    Directory of Open Access Journals (Sweden)

    S. Arpaia

    2014-06-01

    Full Text Available The environmental impacts of genetically modified crops is still a controversial issue in Europe. The overall risk assessment framework has recently been reinforced by the European Food Safety Authority(EFSA and its implementation requires harmonized and efficient methodologies. The EU-funded research project AMIGA − Assessing and monitoring Impacts of Genetically modified plants on Agro-ecosystems − aims to address this issue, by providing a framework that establishes protection goals and baselines for European agro-ecosystems, improves knowledge on the potential long term environmental effects of genetically modified (GM plants, tests the efficacy of the EFSA Guidance Document for the Environmental Risk Assessment, explores new strategies for post market monitoring, and provides a systematic analysis of economic aspects of Genetically Modified crops cultivation in the EU. Research focuses on ecological studies in different EU regions, the sustainability of GM crops is estimated by analysing the functional components of the agro-ecosystems and specific experimental protocols are being developed for this scope.

  3. Agricultural land-use change in a Mexican oligotrophic desert depletes ecosystem stability

    Directory of Open Access Journals (Sweden)

    Natali Hernández-Becerra

    2016-08-01

    Full Text Available Background Global demand for food has led to increased land-use change, particularly in dry land ecosystems, which has caused several environmental problems due to the soil degradation. In the Cuatro Cienegas Basin (CCB, alfalfa production irrigated by flooding impacts strongly on the soil. Methods In order to analyze the effect of such agricultural land-use change on soil nutrient dynamics and soil bacterial community composition, this work examined an agricultural gradient within the CCB which was comprised of a native desert grassland, a plot currently cultivated with alfalfa and a former agricultural field that had been abandoned for over 30 years. For each site, we analyzed C, N and P dynamic fractions, the activity of the enzyme phosphatase and the bacterial composition obtained using 16S rRNA clone libraries. Results The results showed that the cultivated site presented a greater availability of water and dissolved organic carbon, these conditions promoted mineralization processes mediated by heterotrophic microorganisms, while the abandoned land was limited by water and dissolved organic nitrogen. The low amount of dissolved organic matter promoted nitrification, which is mediated by autotrophic microorganisms. The microbial N immobilization process and specific phosphatase activity were both favored in the native grassland. As expected, differences in bacterial taxonomical composition were observed among sites. The abandoned site exhibited similar compositions than native grassland, while the cultivated site differed. Discussion The results suggest that the transformation of native grassland into agricultural land induces drastic changes in soil nutrient dynamics as well as in the bacterial community. However, with the absence of agricultural practices, some of the soil characteristics analyzed slowly recovers their natural state.

  4. Testing functional trait-based mechanisms underpinning plant responses to grazing and linkages to ecosystem functioning in grasslands

    Directory of Open Access Journals (Sweden)

    S. X. Zheng

    2014-09-01

    Full Text Available Abundant evidence has shown that grazing alters plant functional traits, ecological strategies, community structure, and ecosystem functioning of grasslands. Few studies, however, have examined how plant responses to grazing are mediated by resource availability and functional group identity. We test functional trait-based mechanisms underlying the responses of different life forms to grazing and linkages to ecosystem functioning along a soil moisture gradient in the Inner Mongolia grassland. A principal component analysis (PCA based on 9 traits × 276 species matrix showed that the plant size spectrum (i.e., individual biomass, leaf economics spectrum (leaf N content and leaf density, and light competition spectrum (height and stem-leaf biomass ratio distinguished plant species responses to grazing. The three life forms exhibited differential strategies as indicated by trait responses to grazing. The annuals and biennials adopted grazing-tolerant strategies associated with high growth rate, reflected by high leaf N content and specific leaf area. The perennial grasses exhibited grazing-tolerant strategies associated with great regrowth capacity and high palatability scores, whereas perennial forbs showed grazing-avoidant strategies with short stature and low palatability scores. In addition, the dominant perennial bunchgrasses exhibited mixed tolerance–resistance strategies to grazing and mixed acquisitive–conservative strategies in resource utilization. Grazing increased the relative abundance of perennial forbs with low palatability in the wet and fertile meadow, but it promoted perennial grasses with high palatability in the dry and infertile typical steppe. Our findings suggest that the effects of grazing on plant functional traits are dependent on both the abiotic (e.g., soil moisture and biotic (e.g., plant functional group identity and composition factors. Grazing-induced shifts in functional group composition are largely dependent

  5. Testing functional trait-based mechanisms underpinning plant responses to grazing and linkages to ecosystem functioning in grasslands

    Science.gov (United States)

    Zheng, S. X.; Li, W. H.; Lan, Z. C.; Ren, H. Y.; Wang, K. B.; Bai, Y. F.

    2014-09-01

    Abundant evidence has shown that grazing alters plant functional traits, ecological strategies, community structure, and ecosystem functioning of grasslands. Few studies, however, have examined how plant responses to grazing are mediated by resource availability and functional group identity. We test functional trait-based mechanisms underlying the responses of different life forms to grazing and linkages to ecosystem functioning along a soil moisture gradient in the Inner Mongolia grassland. A principal component analysis (PCA) based on 9 traits × 276 species matrix showed that the plant size spectrum (i.e., individual biomass), leaf economics spectrum (leaf N content and leaf density), and light competition spectrum (height and stem-leaf biomass ratio) distinguished plant species responses to grazing. The three life forms exhibited differential strategies as indicated by trait responses to grazing. The annuals and biennials adopted grazing-tolerant strategies associated with high growth rate, reflected by high leaf N content and specific leaf area. The perennial grasses exhibited grazing-tolerant strategies associated with great regrowth capacity and high palatability scores, whereas perennial forbs showed grazing-avoidant strategies with short stature and low palatability scores. In addition, the dominant perennial bunchgrasses exhibited mixed tolerance-resistance strategies to grazing and mixed acquisitive-conservative strategies in resource utilization. Grazing increased the relative abundance of perennial forbs with low palatability in the wet and fertile meadow, but it promoted perennial grasses with high palatability in the dry and infertile typical steppe. Our findings suggest that the effects of grazing on plant functional traits are dependent on both the abiotic (e.g., soil moisture) and biotic (e.g., plant functional group identity and composition) factors. Grazing-induced shifts in functional group composition are largely dependent on resource

  6. Inferring Resilience to Fragmentation-Induced Changes in Plant Communities in a Semi-Arid Mediterranean Ecosystem

    Science.gov (United States)

    de Frutos, Ángel; Navarro, Teresa; Pueyo, Yolanda; Alados, Concepción L.

    2015-01-01

    Predicting the capacity of ecosystems to absorb impacts from disturbance events (resilience), including land-use intensification and landscape fragmentation, is challenging in the face of global change. Little is known about the impacts of fragmentation on ecosystem functioning from a multi-dimensional perspective (multiple traits). This study used 58 500-m linear transects to quantify changes in the functional composition and resilience of vascular plant communities in response to an increase in landscape fragmentation in 18 natural scrubland fragments embedded within a matrix of abandoned crop fields in Cabo de Gata-Níjar Natural Park, Almería, Spain. Changes in functional community composition were measured using functional diversity indices (functional richness and functional dispersion) that were based on 12 plant traits. Resilience was evaluated using the functional redundancy and response diversity from the perspective of plant dispersal, which is important, particularly, in fragmented landscapes. Scrubland fragmentation was measured using the Integral Index of Connectivity (IIC). The functional richness of the plant communities was higher in the most fragmented scrubland. Conversely, the functional dispersion (i.e., spread) of trait values among species in the functional trait space was lower at the most fragmented sites; consequently, the ecological tolerance of the vegetation to scrubland fragmentation decreased. Classifying the plant species into four functional groups indicated that fragmentation favoured an increase in functional redundancy in the ‘short basal annual forbs and perennial forbs’ group, most of which are species adapted to degraded soils. An assessment based on the traits associated with plant dispersal indicated that the resilience of ‘woody plants’, an important component in the Mediterranean scrubland, and habitat fragmentation were negatively correlated; however, the correlation was positive in the ‘short basal annual

  7. Peeking at ecosystem stability: making use of a natural disturbance experiment to analyze resistance and resilience.

    Science.gov (United States)

    Bruelheide, Helge; Luginbühl, Ute

    2009-05-01

    To determine which factors contribute most to the stability of species composition in a beech forest after profound disturbance, we made use of a natural experiment caused by a severe windthrow that occurred at a permanent monitoring site in an old beech forest in Lower Saxony (Germany). The floristic composition was recorded for the succeeding five years after the disturbance and used to derive measures of resistance and resilience for plots as well as for individual species. Due to the existence of previously established randomly distributed permanent plots, we had precise information of the pre-disturbance state, including initial cover of the herb layer, species richness, and species composition. Variables describing the floristic change, resistance, and resilience were derived from correspondence analysis allowing for partitioning the effects of variation among plots from those of temporal change. We asked to which degree these variables could be predicted by pre-disturbance state and disturbance intensity. We found that both the pre-disturbance state and the disturbance intensity were good predictors for floristic change and resistance, while they failed to predict resilience. Among the descriptors of the pre-disturbance state the initial cover of the herb layer turned out to be a useful predictor, which is explained by a high vegetation cover buffering against losses and preventing establishment of newcomers. In contrast, species number neither showed a relationship to floristic change nor to resistance. Putative positive effects of species number on stability according to the insurance hypothesis might have been counterbalanced by a disruption of niche complementarity in species-rich communities. Among the descriptors of disturbance intensity, the loss in canopy cover and the change in photosynthetically active radiation after the storm were equally good predictors for the change in floristic composition and resistance. The analysis of the responses of

  8. Leaf and stem economics spectra drive diversity of functional plant traits in a dynamic global vegetation model

    NARCIS (Netherlands)

    Sakschewski, B.; Bloh, von W.; Boit, A.; Rammig, A.; Kattge, J.; Poorter, L.; Peñualeas, J.; Thonicke, K.

    2015-01-01

    Functional diversity is critical for ecosystem dynamics, stability and productivity. However, dynamic global vegetation models (DGVMs) which are increasingly used to simulate ecosystem functions under global change, condense functional diversity to plant functional types (PFTs) with constant paramet

  9. The stability of ecosystems: A brief overview of the paradox of enrichment

    Indian Academy of Sciences (India)

    Shovonlal Roy; J Chattopadhyay

    2007-03-01

    In theory, enrichment of resource in a predator–prey model leads to desta bilization of the system, thereby collapsing the trophic interaction, a phe nomenon referred to as ``the paradox of enrichment”. After it was first pro posed by Rosenzweig (1971), a number of subsequent studies were carried out on this dilemma over many decades. In this article, we review these the oretical and experimental works and give a brief overview of the proposed solutions to the paradox. The mechanisms that have been discussed are modifications of simple predator–prey models in the presence of prey that is inedible, invulnerable, unpalatable and toxic. Another class of mechanisms includes an incorporation of a ratio-dependent functional form, inducible defence of prey and density-dependent mortality of the predator. Moreover, we find a third set of explanations based on complex population dynamics including chaos in space and time. We conclude that, although any one of the various mechanisms proposed so far might potentially prevent destabilization of the predator–prey dynamics following enrichment, in nature different mechanisms may combine to cause stability, even when a system is enriched. The exact mechanisms, which may differ among systems, need to be disentangled through extensive field studies and labo ratory experiments coupled with realistic theoretical models.

  10. The Date Palm Tree Rhizosphere Is a Niche for Plant Growth Promoting Bacteria in the Oasis Ecosystem

    KAUST Repository

    Ferjani, Raoudha

    2015-04-01

    In arid ecosystems environmental factors such as geoclimatic conditions and agricultural practices are of major importance in shaping the diversity and functionality of plant-associated bacterial communities. Assessing the influence of such factors is a key to understand (i) the driving forces determining the shape of root-associated bacterial communities and (ii) the plant growth promoting (PGP) services they provide. Desert oasis environment was chosen as model ecosystem where agriculture is possible by the microclimate determined by the date palm cultivation. The bacterial communities in the soil fractions associated with the root system of date palms cultivated in seven oases in Tunisia were assessed by culture-independent and dependent approaches. According to 16S rRNA gene PCR-DGGE fingerprinting, the shapes of the date palm rhizosphere bacterial communities correlate with geoclimatic features along a north-south aridity transect. Despite the fact that the date palm root bacterial community structure was strongly influenced by macroecological factors, the potential rhizosphere services reflected in the PGP traits of isolates screened in vitro were conserved among the different oases. Such services were exerted by the 83% of the screened isolates. The comparable numbers and types of PGP traits indicate their importance in maintaining the plant functional homeostasis despite the different environmental selection pressures.

  11. The Date Palm Tree Rhizosphere Is a Niche for Plant Growth Promoting Bacteria in the Oasis Ecosystem

    Directory of Open Access Journals (Sweden)

    Raoudha Ferjani

    2015-01-01

    Full Text Available In arid ecosystems environmental factors such as geoclimatic conditions and agricultural practices are of major importance in shaping the diversity and functionality of plant-associated bacterial communities. Assessing the influence of such factors is a key to understand (i the driving forces determining the shape of root-associated bacterial communities and (ii the plant growth promoting (PGP services they provide. Desert oasis environment was chosen as model ecosystem where agriculture is possible by the microclimate determined by the date palm cultivation. The bacterial communities in the soil fractions associated with the root system of date palms cultivated in seven oases in Tunisia were assessed by culture-independent and dependent approaches. According to 16S rRNA gene PCR-DGGE fingerprinting, the shapes of the date palm rhizosphere bacterial communities correlate with geoclimatic features along a north-south aridity transect. Despite the fact that the date palm root bacterial community structure was strongly influenced by macroecological factors, the potential rhizosphere services reflected in the PGP traits of isolates screened in vitro were conserved among the different oases. Such services were exerted by the 83% of the screened isolates. The comparable numbers and types of PGP traits indicate their importance in maintaining the plant functional homeostasis despite the different environmental selection pressures.

  12. Plant hydraulic responses to long-term dry season nitrogen deposition alter drought tolerance in a Mediterranean-type ecosystem.

    Science.gov (United States)

    Pivovaroff, Alexandria L; Santiago, Louis S; Vourlitis, George L; Grantz, David A; Allen, Michael F

    2016-07-01

    Anthropogenic nitrogen (N) deposition represents a significant N input for many terrestrial ecosystems. N deposition can affect plants on scales ranging from photosynthesis to community composition, yet few studies have investigated how changes in N availability affect plant water relations. We tested the effects of N addition on plant water relations, hydraulic traits, functional traits, gas exchange, and leaf chemistry in a semi-arid ecosystem in Southern California using long-term experimental plots fertilized with N for over a decade. The dominant species were Artemisia california and Salvia mellifera at Santa Margarita Ecological Reserve and Adenostoma fasciculatum and Ceanothus greggii at Sky Oaks Field Station. All species, except Ceanothus, showed increased leaf N concentration, decreased foliar carbon to N ratio, and increased foliar N isotopic composition with fertilization, indicating that added N was taken up by study species, yet each species had a differing physiological response to long-term N addition. Dry season predawn water potentials were less negative with N addition for all species except Adenostoma, but there were no differences in midday water potentials, or wet season water potentials. Artemisia was particularly responsive, as N addition increased stem hydraulic conductivity, stomatal conductance, and leaf carbon isotopic composition, and decreased wood density. The alteration of water relations and drought resistance parameters with N addition in Artemisia, as well as Adenostoma, Ceanothus, and Salvia, indicate that N deposition can affect the ability of native Southern California shrubs to respond to drought.

  13. Wind Turbine and Wind Power Plant Modelling Aspects for Power System Stability Studies

    DEFF Research Database (Denmark)

    Altin, Müfit; Hansen, Anca Daniela; Göksu, Ömer;

    2014-01-01

    turbine model which is developed for the short-term voltage stability studies can be inaccurate and sufficient for the frequency stability studies. Accordingly, a complete and detailed wind power plant model for every kind of study is not feasible in terms of the computational time and also...... is not reasonable regarding the focus of the study. Therefore the power system operators should be aware of the modelling aspects of the wind power considering the related stability study and implement the required model in the appropriate power system toolbox. In this paper, the modelling aspects of wind turbines...... and wind power plants are reviewed for power system stability studies. Important remarks of the models are presented by means of simulations to emphasize the impact of these modelling details on the power system....

  14. Simultaneous Stabilization for a Family of Plants%一组系统的同时稳定性

    Institute of Scientific and Technical Information of China (English)

    卢玉峰; 徐晓萍

    2008-01-01

    In this paper, we discuss the problem of simultaneous stabilization for plants more than three by using Youla parametrization[1] and give a necessary and sufficient condition for simultaneous stabilization.

  15. A conceptual framework for an ecosystem services-based assessment of the so-called "emergency stabilization" measures following wildfire

    Science.gov (United States)

    Valente, Sandra; Prats, Sergio; Ribeiro, Cristina; Verheijen, Frank; Fleskens, Luuk; Keizer, Jacob

    2015-04-01

    Wildfires have become a major environmental concern in many Southern European countries over the past few decades. This includes Portugal, where, on average, some 100 000 ha of rural lands are affected by wildfire every year. While policies, laws, plans and public expenditure in Portugal continue to be largely directed towards fire combat and, arguably, to a lesser extent fire prevention, there has only recently been increasing attention for post-fire land management. For example following frequent and several large wildfires during the summer of 2010, so-called emergency stabilization measures were implemented in 16 different burnt areas in northern and central Portugal, using funds of the EU Rural Development Plan in Portugal (PRODER). The measures that were implemented included mulching (i.e. application of a protective layer of organic material), seeding and the construction of log barriers. However, the effectiveness of the implemented measures has not been monitored or otherwise assessed in a systematic manner. In fact, until very recently none of the post-fire emergency stabilization measures contemplated under PRODER seem to have been studied in an exhaustive manner in Portugal, whether under laboratory or field conditions. Prats et al. (2012, 2013, 2014) tested two of these measures by field trials, i.e. hydro-mulching and forest residue mulching. The authors found both measures to be highly effective in terms of reducing overland flow and especially erosion. It remains a challenge, however, to assess the effectiveness of these and other measures in a broader context, not only beyond overland flow and sediment losses but also beyond the spatio-temporal scale that are typical for such field trials (plots and the first two years after fire). This challenge will be addressed in the Portuguese case study of the RECARE project. Nonetheless, the present study wants to be a first attempt at an ecosystem services-based assessment of mulching as a post

  16. Trade-offs Between Electricity Production from Small Hydropower Plants and Ecosystem Services in Alpine River Basins

    Science.gov (United States)

    Meier, Philipp; Schwemmle, Robin; Viviroli, Daniel

    2015-04-01

    The need for a reduction in greenhouse gas emissions and the decision to phase out nuclear power plants in Switzerland and Germany increases pressure to develop the remaining hydropower potential in Alpine catchments. Since most of the potential for large reservoirs is already exploited, future development focusses on small run-of-the-river hydropower plants (SHP). Being considered a relatively environment-friendly electricity source, investment in SHP is promoted through subsidies. However, SHP can have a significant impact on riverine ecosystems, especially in the Alpine region where residual flow reaches tend to be long. An increase in hydropower exploitation will therefore increase pressure on ecosystems. While a number of studies assessed the potential for hydropower development in the Alps, two main factors were so far not assessed in detail: (i) ecological impacts within a whole river network, and (ii) economic conditions under which electricity is sold. We present a framework that establishes trade-offs between multiple objectives regarding environmental impacts, electricity production and economic evaluation. While it is inevitable that some ecosystems are compromised by hydropower plants, the context of these impacts within a river network should be considered when selecting suitable sites for SHP. From an ecological point of view, the diversity of habitats, and therefore the diversity of species, should be maintained within a river basin. This asks for objectives that go beyond lumped parameters of hydrological alteration, but also consider habitat diversity and the spatial configuration. Energy production in run-of-the-river power plants depends on available discharge, which can have large fluctuations. In a deregulated electricity market with strong price variations, an economic valuation should therefore be based on the expected market value of energy produced. Trade-off curves between different objectives can help decision makers to define policies

  17. [Changes of plant leaf N, P, and K concentrations and species dominance in an arid-hot valley after ecosystem restoration].

    Science.gov (United States)

    Yan, Bang-guo; He, Guang-xiong; Li, Ji-chao; Qian, Kun-jian; Kui, Jian-rui; Pan, Zhi-xian; Shi, Liang-tao; Ji, Zhong-hua

    2013-04-01

    Taking the arid-hot valley of Jinsha River, Southwest China as the object, a comparative study was made on the plant leaf N, P, and K concentrations and ratios as well as their relationships with species dominance in the restoration area and disturbed area, aimed to understand the effects of ecosystem restoration on the plant leaf stoichoimetric characteristics. Ecosystem restoration decreased the plant leaf N and P concentrations and P/K ratio significantly, but had lesser effects on the plant leaf K concentration. In restoration area, the plant leaf N, P, and K concentrations were averagely 10. 405, 0. 604, and 9. 619 g kg-1, being 16. 9% , 34. 9% , and 4. 7% lower than those in disturbed area, respectively. In restoration area, species dominance was significantly negatively correlated with plant leaf P concentration; while the species dominance in disturbed area had a significant negative correlation with plant leaf K concentration. Ecosystem restoration altered the slope and intercept of the scaling relationships among the plant leaf N, P, and K. No significant differences were observed in the leaf N, P, and K concentrations of the same plant species between restoration area and disturbed area, suggesting that the changes of plant leaf stoichiometric characteristics were mainly driven by the shift of species composition in the plant community.

  18. Ecosystem consequences of plant genetic divergence with colonization of new habitat

    Science.gov (United States)

    Liam O. Mueller; Lauren C. Breza; Mark A. Genung; Christian P. Giardina; Nathan E. Stone; Lindsay C. Sidak-Loftis; Joseph D. Busch; David M. Wagner; Joseph K. Bailey; Jennifer A. Schweitzer

    2017-01-01

    When plants colonize new habitats altered by natural or anthropogenic disturbances, those individuals may encounter biotic and abiotic conditions novel to the species, which can cause plant functional trait divergence. Over time, site-driven adaptation can give rise to population-level genetic variation, with consequences for plant community dynamics and...

  19. Stability Analysis of DC-link Voltage Control on Autonomous Micro Hydro Power Plant System

    OpenAIRE

    Feri Yusivar; M. Shanizal; A. Subiantoro; Gunawan, R

    2014-01-01

    Micro Hydro Power Plant has become one of the interesting topics to be researched nowadays. This paper deals with the stability analysis on control system of excitation voltage in Micro Hydro Power Plant. The control of this voltage can be achieved by controlling the Permanent Magnet Synchronous Machine (PMSM) with particular algorithm so the voltage on the DC-link part of the system can be controlled. Without knowing the exact specification of system parameters, the system will be most likel...

  20. Temporal stability of soil moisture in various semi-arid steppe ecosystems and its application in remote sensing

    Science.gov (United States)

    Schneider, K.; Huisman, J. A.; Breuer, L.; Zhao, Y.; Frede, H.-G.

    2008-09-01

    SummaryMonitoring soil moisture is often necessary in hydrological studies on various scales. One of the challenges is to determine the mean soil moisture of large areas with minimum labour and costs. The aim of this study is to test temporal persistence of sample locations to decrease the number of samples required to make reliable estimates of mean moisture content in the top soil. Soil moisture data on four experimental sites were collected during the vegetation period in 2004-2006. The experimental sites are located in a steppe environment in northern China, and are characterised by different grazing management which causes differences in vegetation cover. A total of 100 sampling points per site were ranked with respect to their difference to field mean soil moisture using the time-stability concept. We tested whether: (a) representative sample locations exist that predict field mean soil moisture to an acceptable degree, and (b) these locations are time-stable beyond a single vegetation period. Time-stable locations with a low deviation from mean field soil moisture and low standard deviation were identified for each site. Although the time-stability characteristics of some points varied between years, the selected points were appropriate to predict mean soil moisture of the sites for multiple years. On the field scale, time-stability and the persistence of patterns were analysed by the use of a Spearman rank correlation. The analysis showed that persistence depended on grazing management and the related plant cover. It is concluded that the time-stability concept provides useful information for the validation of hydrological or remote sensing models, or for the upscaling of soil moisture information to larger scales. A preliminary comparison of soil moisture measurements derived from ground-truth and remote sensing data showed that the data matched well in some cases, but that the considerable difference in spatial extent promotes differences in other cases.

  1. Plants from Chernobyl zone could shed light on genome stability in radioactive environment

    Science.gov (United States)

    Shevchenko, Galina; Talalaiev, Oleksandr; Doonan, John

    2016-07-01

    For nearly 30 years, despite of chronic radiation, flora in Chernobyl zone continue to flourish, evidencing the adaptation of plants to such an environment. Keeping in mind interplanetary missions, this phenomenon is a challenge for plant space research since it highlights the possible mechanisms of genome protection and stabilization in harmful environment. Plants are sessile organisms and, contrary to animals, could not escape the external impact. Therefore, plants should evolve the robust system allowing DNA-protection against damage, which is of special interest. Our investigations show that Arabidopsis thaliana from Chernobyl zone tolerate radiomimetics and heavy metals better than control plants from non-polluted areas. Besides, its genome is less affected by such mutagens. qPCR investigations have revealed up-regulation of some genes involved in DNA damage response. In particular, expression of ATR is increased slightly and downstream expression of CycB1:1 gene is increased significantly after bleomycin treatment suggesting role of ATR-dependent pathway in genome stabilization. Several DNA repair pathways are known to exist in plants. We continue investigations on gene expression from different DNA repair pathways as well as cell cycle regulation and investigation of PCD hallmarks in order to reveal the mechanism of plant tolerance to radiation environment. Our investigations provide unique information for space researchers working on biotechnology of radiation tolerant plants.

  2. Invasive plants have different effects on trophic structure of green and brown food webs in terrestrial ecosystems: a meta-analysis.

    Science.gov (United States)

    McCary, Matthew A; Mores, Robin; Farfan, Monica A; Wise, David H

    2016-03-01

    Although invasive plants are a major source of terrestrial ecosystem degradation worldwide, it remains unclear which trophic levels above the base of the food web are most vulnerable to plant invasions. We performed a meta-analysis of 38 independent studies from 32 papers to examine how invasive plants alter major groupings of primary and secondary consumers in three globally distributed ecosystems: wetlands, woodlands and grasslands. Within each ecosystem we examined if green (grazing) food webs are more sensitive to plant invasions compared to brown (detrital) food webs. Invasive plants have strong negative effects on primary consumers (detritivores, bacterivores, fungivores, and/or herbivores) in woodlands and wetlands, which become less abundant in both green and brown food webs in woodlands and green webs in wetlands. Plant invasions increased abundances of secondary consumers (predators and/or parasitoids) only in woodland brown food webs and green webs in wetlands. Effects of invasive plants on grazing and detrital food webs clearly differed between ecosystems. Overall, invasive plants had the most pronounced effects on the trophic structure of wetlands and woodlands, but caused no detectable changes to grassland trophic structure. © 2016 John Wiley & Sons Ltd/CNRS.

  3. How plants connect pollination and herbivory networks and their contribution to community stability.

    Science.gov (United States)

    Sauve, Alix M C; Thébault, Elisa; Pocock, Michael J O; Fontaine, Colin

    2016-04-01

    Pollination and herbivory networks have mainly been studied separately, highlighting their distinct structural characteristics and the related processes and dynamics. However, most plants interact with both pollinators and herbivores, and there is evidence that both types of interaction affect each other. Here we investigated the way plants connect these mutualistic and antagonistic networks together, and the consequences for community stability. Using an empirical data set, we show that the way plants connect pollination and herbivory networks is not random and promotes community stability. Analyses of the structure of binary and quantitative networks show different results: the plants' generalism with regard to pollinators is positively correlated to their generalism with regard to herbivores when considering binary interactions, but not when considering quantitative interactions. We also show that plants that share the same pollinators do not share the same herbivores. However, the way plants connect pollination and herbivory networks promotes stability for both binary and quantitative networks. Our results highlight the relevance of considering the diversity of interaction types in ecological communities, and stress the need to better quantify the costs and benefits of interactions, as well as to develop new metrics characterizing the way different interaction types are combined within ecological networks.

  4. Accumulation and environmental risk assessment of heavy metals in soil and plants of four different ecosystems in a former polymetallic ores mining and smelting area (Slovakia).

    Science.gov (United States)

    Demková, Lenka; Árvay, Július; Bobuľská, Lenka; Tomáš, Ján; Stanovič, Radovan; Lošák, Tomáš; Harangozo, Luboš; Vollmannová, Alena; Bystrická, Judita; Musilová, Janette; Jobbágy, Ján

    2017-04-16

    Heavy metals (Cd, Co, Cr, Cu, Fe, Mn, Ni, Pb, and Zn) in soils and plants of four different ecosystems (forest, grassland, agro and urban ecosystem) at different distances from the source of the pollution were analyzed in order to assess and compare soil contamination in the various ecosystems and determine the potential accumulation of plants depending on the place they inhabit. Correlation relationships among heavy metals in soils differ depending on the ecosystem, and between soil and plant, the heavy metals showed significant correlation for Cu, Mn, Ni, Pb and Zn. Contamination factor (Cf), degree of contamination (Cd) and pollution load index (PLI) were used in order to determine the level of environmental contamination of the study area. All studied ecosystems were rated as moderately contaminated (except agroecosystem, which was found as low contamination ecosystem) according to Cd and extremely polluted according to PLI. The highest pollution in both cases was found in urban ecosystem, and Cd, Cu and Fe were determined as the biggest pollutants.

  5. Accounting for multiple stressors in regional stream ecosystem analysis: A demonstration with riparian invasive plants

    Science.gov (United States)

    Background/Questions/Methods: Large cross-sectional data sets allow testing of hypotheses about how one part of an ecosystem relates to other parts. Tests such as these are of interest for many reasons, one of which is to gain insight into the role of stressors, such as land co...

  6. Belowground plant biomass allocation in tundra ecosystems and its relationship with temperature

    NARCIS (Netherlands)

    Peng, Wang; Heijmans, M.M.P.D.; Mommer, L.; Ruijven, van J.; Maximov, Trofim C.; Berendse, F.

    2016-01-01

    Climatewarming is known to increase the aboveground productivity of tundra ecosystems.
    Recently, belowground biomass is receiving more attention, but the effects of climate warming on
    belowground productivity remain unclear. Enhanced understanding of the belowground component
    of the tund

  7. Very high resolution time-lapse photography for plant and ecosystems research

    Science.gov (United States)

    Very high resolution gigapixel photography increasingly is being used to support a broad range of ecosystem and physical process research because it offers an inexpensive means of simultaneously collecting information at a range of spatial scales. Recently, methods have been developed to incorporate...

  8. Twelve years of repeated wild hog activity promotes population maintenance of an invasive clonal plant in a coastal dune ecosystem.

    Science.gov (United States)

    Oldfield, Callie A; Evans, Jonathan P

    2016-04-01

    Invasive animals can facilitate the success of invasive plant populations through disturbance. We examined the relationship between the repeated foraging disturbance of an invasive animal and the population maintenance of an invasive plant in a coastal dune ecosystem. We hypothesized that feral wild hog (Sus scrofa) populations repeatedly utilized tubers of the clonal perennial, yellow nutsedge (Cyperus esculentus) as a food source and evaluated whether hog activity promoted the long-term maintenance of yellow nutsedge populations on St. Catherine's Island, Georgia, United States. Using generalized linear mixed models, we tested the effect of wild hog disturbance on permanent sites for yellow nutsedge culm density, tuber density, and percent cover of native plant species over a 12-year period. We found that disturbance plots had a higher number of culms and tubers and a lower percentage of native live plant cover than undisturbed control plots. Wild hogs redisturbed the disturbed plots approximately every 5 years. Our research provides demographic evidence that repeated foraging disturbances by an invasive animal promote the long-term population maintenance of an invasive clonal plant. Opportunistic facultative interactions such as we demonstrate in this study are likely to become more commonplace as greater numbers of introduced species are integrated into ecological communities around the world.

  9. Ecosystem Carbon Stock Influenced by Plantation Practice: Implications for Planting Forests as a Measure of Climate Change Mitigation

    Science.gov (United States)

    Liao, Chengzhang; Luo, Yiqi; Fang, Changming; Li, Bo

    2010-01-01

    Uncertainties remain in the potential of forest plantations to sequestrate carbon (C). We synthesized 86 experimental studies with paired-site design, using a meta-analysis approach, to quantify the differences in ecosystem C pools between plantations and their corresponding adjacent primary and secondary forests (natural forests). Totaled ecosystem C stock in plant and soil pools was 284 Mg C ha−1 in natural forests and decreased by 28% in plantations. In comparison with natural forests, plantations decreased aboveground net primary production, litterfall, and rate of soil respiration by 11, 34, and 32%, respectively. Fine root biomass, soil C concentration, and soil microbial C concentration decreased respectively by 66, 32, and 29% in plantations relative to natural forests. Soil available N, P and K concentrations were lower by 22, 20 and 26%, respectively, in plantations than in natural forests. The general pattern of decreased ecosystem C pools did not change between two different groups in relation to various factors: stand age (plantations, land-use history (afforestation vs. reforestation) and site preparation for plantations (unburnt vs. burnt), and study regions (tropic vs. temperate). The pattern also held true across geographic regions. Our findings argued against the replacement of natural forests by the plantations as a measure of climate change mitigation. PMID:20523733

  10. Ecosystem carbon stock influenced by plantation practice: implications for planting forests as a measure of climate change mitigation.

    Directory of Open Access Journals (Sweden)

    Chengzhang Liao

    Full Text Available Uncertainties remain in the potential of forest plantations to sequestrate carbon (C. We synthesized 86 experimental studies with paired-site design, using a meta-analysis approach, to quantify the differences in ecosystem C pools between plantations and their corresponding adjacent primary and secondary forests (natural forests. Totaled ecosystem C stock in plant and soil pools was 284 Mg C ha(-1 in natural forests and decreased by 28% in plantations. In comparison with natural forests, plantations decreased aboveground net primary production, litterfall, and rate of soil respiration by 11, 34, and 32%, respectively. Fine root biomass, soil C concentration, and soil microbial C concentration decreased respectively by 66, 32, and 29% in plantations relative to natural forests. Soil available N, P and K concentrations were lower by 22, 20 and 26%, respectively, in plantations than in natural forests. The general pattern of decreased ecosystem C pools did not change between two different groups in relation to various factors: stand age ( or = 25 years, stand types (broadleaved vs. coniferous and deciduous vs. evergreen, tree species origin (native vs. exotic of plantations, land-use history (afforestation vs. reforestation and site preparation for plantations (unburnt vs. burnt, and study regions (tropic vs. temperate. The pattern also held true across geographic regions. Our findings argued against the replacement of natural forests by the plantations as a measure of climate change mitigation.

  11. Ecosystem carbon stock influenced by plantation practice: implications for planting forests as a measure of climate change mitigation.

    Science.gov (United States)

    Liao, Chengzhang; Luo, Yiqi; Fang, Changming; Li, Bo

    2010-05-27

    Uncertainties remain in the potential of forest plantations to sequestrate carbon (C). We synthesized 86 experimental studies with paired-site design, using a meta-analysis approach, to quantify the differences in ecosystem C pools between plantations and their corresponding adjacent primary and secondary forests (natural forests). Totaled ecosystem C stock in plant and soil pools was 284 Mg C ha(-1) in natural forests and decreased by 28% in plantations. In comparison with natural forests, plantations decreased aboveground net primary production, litterfall, and rate of soil respiration by 11, 34, and 32%, respectively. Fine root biomass, soil C concentration, and soil microbial C concentration decreased respectively by 66, 32, and 29% in plantations relative to natural forests. Soil available N, P and K concentrations were lower by 22, 20 and 26%, respectively, in plantations than in natural forests. The general pattern of decreased ecosystem C pools did not change between two different groups in relation to various factors: stand age ( or = 25 years), stand types (broadleaved vs. coniferous and deciduous vs. evergreen), tree species origin (native vs. exotic) of plantations, land-use history (afforestation vs. reforestation) and site preparation for plantations (unburnt vs. burnt), and study regions (tropic vs. temperate). The pattern also held true across geographic regions. Our findings argued against the replacement of natural forests by the plantations as a measure of climate change mitigation.

  12. Ecosystem fluxes of hydrogen in a mid-latitude forest driven by soil microorganisms and plants.

    Science.gov (United States)

    Meredith, Laura K; Commane, Róisín; Keenan, Trevor F; Klosterman, Stephen T; Munger, J William; Templer, Pamela H; Tang, Jianwu; Wofsy, Steven C; Prinn, Ronald G

    2017-02-01

    Molecular hydrogen (H2 ) is an atmospheric trace gas with a large microbe-mediated soil sink, yet cycling of this compound throughout ecosystems is poorly understood. Measurements of the sources and sinks of H2 in various ecosystems are sparse, resulting in large uncertainties in the global H2 budget. Constraining the H2 cycle is critical to understanding its role in atmospheric chemistry and climate. We measured H2 fluxes at high frequency in a temperate mixed deciduous forest for 15 months using a tower-based flux-gradient approach to determine both the soil-atmosphere and the net ecosystem flux of H2 . We found that Harvard Forest is a net H2 sink (-1.4 ± 1.1 kg H2  ha(-1) ) with soils as the dominant H2 sink (-2.0 ± 1.0 kg H2  ha(-1) ) and aboveground canopy emissions as the dominant H2 source (+0.6 ± 0.8 kg H2  ha(-1) ). Aboveground emissions of H2 were an unexpected and substantial component of the ecosystem H2 flux, reducing net ecosystem uptake by 30% of that calculated from soil uptake alone. Soil uptake was highly seasonal (July maximum, February minimum), positively correlated with soil temperature and negatively correlated with environmental variables relevant to diffusion into soils (i.e., soil moisture, snow depth, snow density). Soil microbial H2 uptake was correlated with rhizosphere respiration rates (r = 0.8, P soil H2 and carbon cycling. Results from this study should be incorporated into modeling efforts to predict the response of the H2 soil sink to changes in anthropogenic H2 emissions and shifting soil conditions with climate and land-use change. © 2016 John Wiley & Sons Ltd.

  13. New Challenges for the Design of High Value Plant Products: Stabilization of Anthocyanins in Plant Vacuoles

    NARCIS (Netherlands)

    Passeri, V.; Koes, R.; Quattrocchio, F.M.

    2016-01-01

    In the last decade plant biotechnologists and breeders have made several attempt to improve the antioxidant content of plant-derived food. Most efforts concentrated on increasing the synthesis of antioxidants, in particular anthocyanins, by inducing the transcription of genes encoding the synthesizi

  14. The impact of livestock grazing on plant diversity: an analysis across dryland ecosystems and scales in southern Africa.

    Science.gov (United States)

    Hanke, Wiebke; Böhner, Jürgen; Dreber, Niels; Jürgens, Norbert; Schmiedel, Ute; Wesuls, Dirk; Dengler, Jürgen

    2014-07-01

    A general understanding of grazing effects on plant diversity in drylands is still missing, despite an extensive theoretical background. Cross-biome syntheses are hindered by the fact that the outcomes of disturbance studies are strongly affected by the choice of diversity measures, and the spatial and temporal scales of measurements. The aim of this study is to overcome these weaknesses by applying a wide range of diversity measures to a data set derived from identical sampling in three distinct ecosystems. We analyzed three fence-line contrasts (heavier vs. lighter grazing intensity), representing different degrees of aridity (from arid to semiarid) and precipitation regimes (summer rain vs. winter rain) in southern Africa. We tested the impact of grazing intensity on multiple aspects of plant diversity (species and functional group level, richness and evenness components, alpha and beta diversity, and composition) at two spatial scales, and for both 5-yr means and interannual variability. Heavier grazing reduced total plant cover and substantially altered the species and functional composition at all sites. However, a significant decrease in species alpha diversity was detected at only one of the three sites. By contrast, alpha diversity of plant functional groups responded consistently across ecosystems and scales, with a significant decrease at heavier grazing intensity. The cover-based measures of functional group diversity responded more sensitively and more consistently than functional group richness. Beta diversity of species and functional types increased under heavier grazing, showing that at larger scales, the heterogeneity of the community composition and the functional structure were increased. Heavier grazing mostly increased interannual variability of alpha diversity, while effects on beta diversity and cover were inconsistent. Our results suggest that species diversity alone may not adequately reflect the shifts in vegetation structure that occur

  15. Stabilization

    Directory of Open Access Journals (Sweden)

    Muhammad H. Al-Malack

    2016-07-01

    Full Text Available Fuel oil flyash (FFA produced in power and water desalination plants firing crude oils in the Kingdom of Saudi Arabia is being disposed in landfills, which increases the burden on the environment, therefore, FFA utilization must be encouraged. In the current research, the effect of adding FFA on the engineering properties of two indigenous soils, namely sand and marl, was investigated. FFA was added at concentrations of 5%, 10% and 15% to both soils with and without the addition of Portland cement. Mixtures of the stabilized soils were thoroughly evaluated using compaction, California Bearing Ratio (CBR, unconfined compressive strength (USC and durability tests. Results of these tests indicated that stabilized sand mixtures could not attain the ACI strength requirements. However, marl was found to satisfy the ACI strength requirement when only 5% of FFA was added together with 5% of cement. When the FFA was increased to 10% and 15%, the mixture’s strength was found to decrease to values below the ACI requirements. Results of the Toxicity Characteristics Leaching Procedure (TCLP, which was performed on samples that passed the ACI requirements, indicated that FFA must be cautiously used in soil stabilization.

  16. Prosopis laevigata and Mimosa biuncifera (Leguminosae, jointly influence plant diversity and soil fertility of a Mexican semiarid ecosystem

    Directory of Open Access Journals (Sweden)

    Rosalva García-Sánchez

    2012-03-01

    Full Text Available Prosopis laevigata and Mimosa biuncifera are frequently found in arid and semiarid shrublands, but scarce information is available about their influence on plant community structure and soil fertility. We compared plant community structure, diversity and soil nutrients of three semiarid shrubland sites located in Mezquital Valley, Mexico. These sites differ in their dominant species: Site 1 (Bingu P. laevigata, Site 2 (González M. biuncifera, and Site 3 (Rincón with the presence of both legumes. The results showed that the plant community with P. laevigata and M. biuncifera (Site 3 had more cover, taller plants and higher plant diversity than sites with only one legume (Site 1 and Site 2. Soil organic matter (SOM, soil organic carbon (SOC, total nitrogen (TN, phosphorus-Olsen (P and C mineralization were higher in the soil under the canopy of both legumes than in bare soil. In contrast, soil cation concentrations were lower under the canopy of P. laevigata, but not for M. biuncifera. In addition, the density of arbuscular mycorrhizal fungi spores was higher within the soil under the canopy of M. biuncifera than in the soil under the canopy of P. laevigata. Thus, resource islands (RI created by P. laevigata increased the amounts of SOC, TN and P when compared with the RI of M. biuncifera. This study provided evidences about the importance of species identity in order to expand the niche availability for the establishment of other plants, and highlights that P. laevigata and M. biuncifera jointly influencing plant colonization within semiarid ecosystems

  17. Prosopis laevigata and Mimosa biuncifera (Leguminosae), jointly influence plant diversity and soil fertility of a Mexican semiarid ecosystem.

    Science.gov (United States)

    García-Sánchez, Rosalva; Camargo-Ricalde, Sara Lucía; García-Moya, Edmundo; Luna-Cavazos, Mario; Romero-Manzanares, Angélica; Montaño, Noé Manuel

    2012-03-01

    Prosopis laevigata and Mimosa biuncifera are frequently found in arid and semiarid shrublands, but scarce information is available about their influence on plant community structure and soil fertility. We compared plant community structure, diversity and soil nutrients of three semiarid shrubland sites located in Mezquital Valley, Mexico. These sites differ in their dominant species: Site 1 (Bingu) P. laevigata, Site 2 (González) M. biuncifera, and Site 3 (Rincón) with the presence of both legumes. The results showed that the plant community with P. laevigata and M. biuncifera (Site 3) had more cover, taller plants and higher plant diversity than sites with only one legume (Site 1 and Site 2). Soil organic matter (SOM), soil organic carbon (SOC), total nitrogen (TN), phosphorus-Olsen (P) and C mineralization were higher in the soil under the canopy of both legumes than in bare soil. In contrast, soil cation concentrations were lower under the canopy of P. laevigata, but not for M. biuncifera. In addition, the density of arbuscular mycorrhizal fungi spores was higher within the soil under the canopy of M. biuncifera than in the soil under the canopy of P. laevigata. Thus, resource islands (RI) created by P. laevigata increased the amounts of SOC, TN and P when compared with the RI of M. biuncifera. This study provided evidences about the importance of species identity in order to expand the niche availability for the establishment of other plants, and highlights that P. laevigata and M. biuncifera jointly influencing plant colonization within semiarid ecosystems.

  18. Biological effects of carbon nanotubes generated in forest wildfire ecosystems rich in resinous trees on native plants

    Directory of Open Access Journals (Sweden)

    Javier Lara-Romero

    2017-08-01

    Full Text Available Carbon nanotubes (CNTs have a broad range of applications and are generally considered human-engineered nanomaterials. However, carbon nanostructures have been found in ice cores and oil wells, suggesting that nature may provide appropriate conditions for CNT synthesis. During forest wildfires, materials such as turpentine and conifer tissues containing iron under high temperatures may create chemical conditions favorable for CNT generation, similar to those in synthetic methods. Here, we show evidence of naturally occurring multiwalled carbon nanotubes (MWCNTs produced from Pinus oocarpa and Pinus pseudostrobus, following a forest wildfire. The MWCNTs showed an average of 10 walls, with internal diameters of ∼2.5 nm and outer diameters of ∼14.5 nm. To verify whether MWCNT generation during forest wildfires has a biological effect on some characteristic plant species of these ecosystems, germination and development of seedlings were conducted. Results show that the utilization of comparable synthetic MWCNTs increased seed germination rates and the development of Lupinus elegans and Eysenhardtia polystachya, two plants species found in the burned forest ecosystem. The finding provides evidence that supports the generation and possible ecological functions of MWCNTs in nature.

  19. Solar ultraviolet-B radiation affects plant-insect interactions in a natural ecosystem of Tierra del Fuego (southern Argentina).

    Science.gov (United States)

    Rousseaux, M Cecilia; Ballaré, Carlos L; Scopel, Ana L; Searles, Peter S; Caldwell, Martyn M

    1998-10-01

    We examined the effects of solar ultraviolet-B radiation (UVB) on plant-herbivore interactions in native ecosystems of the Tierra del Fuego National Park (southern Argentina), an area of the globe that is frequently under the Antarctic "ozone hole" in early spring. We found that filtering out solar UVB from the sunlight received by naturally-occurring plants of Gunnera magellanica, a creeping perennial herb, significantly increased the number of leaf lesions caused by chewing insects. Field surveys suggested that early-season herbivory was principally due to the activity of moth larvae (Lepidoptera: Noctuidae). Manipulative field experiments showed that exposure to solar UVB changes the attractiveness of G. magellanica leaf tissue to natural grazers. In a laboratory experiment, locally caught moth caterpillars tended to eat more tissue from leaves grown without UVB than from leaves exposed to natural UVB during development; however, the difference between treatments was not significant. Leaves grown under solar UVB had slightly higher N levels than leaves not exposed to UVB; no differences between UVB treatments in specific leaf mass, relative water content, and total methanol-soluble phenolics were detected. Our results show that insect herbivory in a natural ecosystem is influenced by solar UVB, and that this influence could not be predicted from crude measurements of leaf physical and chemical characteristics and a common laboratory bioassay.

  20. Ant aggression and evolutionary stability in plant-ant and plant-pollinator mutualistic interactions.

    Science.gov (United States)

    Oña, L; Lachmann, M

    2011-03-01

    Mutualistic partners derive a benefit from their interaction, but this benefit can come at a cost. This is the case for plant-ant and plant-pollinator mutualistic associations. In exchange for protection from herbivores provided by the resident ants, plants supply various kinds of resources or nests to the ants. Most ant-myrmecophyte mutualisms are horizontally transmitted, and therefore, partners share an interest in growth but not in reproduction. This lack of alignment in fitness interests between plants and ants drives a conflict between them: ants can attack pollinators that cross-fertilize the host plants. Using a mathematical model, we define a threshold in ant aggressiveness determining pollinator survival or elimination on the host plant. In our model we observed that, all else being equal, facultative interactions result in pollinator extinction for lower levels of ant aggressiveness than obligatory interactions. We propose that the capacity to discriminate pollinators from herbivores should not often evolve in ants, and when it does it will be when the plants exhibit limited dispersal in an environment that is not seed saturated so that each seed produced can effectively generate a new offspring or if ants acquire an extra benefit from pollination (e.g. if ants eat fruit). We suggest specific mutualism examples where these hypotheses can be tested empirically. © 2010 The Authors. Journal of Evolutionary Biology © 2010 European Society For Evolutionary Biology.

  1. Soil and plant responses to pyrogenic organic matter: carbon stability and symbiotic patterns

    NARCIS (Netherlands)

    Sagrilo, E.

    2014-01-01

    Soil and plant responses to pyrogenic organic matter: carbon stability and symbiotic patterns Edvaldo Sagrilo Summary Pyrogenic organic matter (PyOM), also known as biochar, is the product of biomass combustion under low oxygen concentration. There

  2. Soil and plant responses to pyrogenic organic matter: carbon stability and symbiotic patterns

    NARCIS (Netherlands)

    Sagrilo, E.

    2014-01-01

    Soil and plant responses to pyrogenic organic matter: carbon stability and symbiotic patterns Edvaldo Sagrilo Summary Pyrogenic organic matter (PyOM), also known as biochar, is the product of biomass combustion under low oxygen concentration. There

  3. Proportional derivative based stabilizing control of paralleled grid converters with cables in renewable power plants

    DEFF Research Database (Denmark)

    Wang, Xiongfei; Blaabjerg, Frede; Loh, Poh Chiang

    2014-01-01

    Resonant interactions of grid-connected converters with each other and with cable capacitance are challenging the stability and power quality of renewable energy sources based power plants. This paper addresses the instability of current control of converters with the multiple resonance frequenci...

  4. The Influence of Plant Root Systems on Subsurface Flow: Implications for Slope Stability

    Science.gov (United States)

    Although research has explained how plant roots mechanically stabilize soils, in this article we explore how root systems create networks of preferential flow and thus influence water pressures in soils to trigger landslides. Root systems may alter subsurface flow: Hydrological m...

  5. Enhanced seasonal CO2 exchange caused by amplified plant productivity in northern ecosystems.

    Science.gov (United States)

    Forkel, Matthias; Carvalhais, Nuno; Rödenbeck, Christian; Keeling, Ralph; Heimann, Martin; Thonicke, Kirsten; Zaehle, Sönke; Reichstein, Markus

    2016-02-12

    Atmospheric monitoring of high northern latitudes (above 40°N) has shown an enhanced seasonal cycle of carbon dioxide (CO2) since the 1960s, but the underlying mechanisms are not yet fully understood. The much stronger increase in high latitudes relative to low ones suggests that northern ecosystems are experiencing large changes in vegetation and carbon cycle dynamics. We found that the latitudinal gradient of the increasing CO2 amplitude is mainly driven by positive trends in photosynthetic carbon uptake caused by recent climate change and mediated by changing vegetation cover in northern ecosystems. Our results underscore the importance of climate-vegetation-carbon cycle feedbacks at high latitudes; moreover, they indicate that in recent decades, photosynthetic carbon uptake has reacted much more strongly to warming than have carbon release processes.

  6. Habitat area and climate stability determine geographical variation in plant species range sizes.

    Science.gov (United States)

    Morueta-Holme, Naia; Enquist, Brian J; McGill, Brian J; Boyle, Brad; Jørgensen, Peter M; Ott, Jeffrey E; Peet, Robert K; Símová, Irena; Sloat, Lindsey L; Thiers, Barbara; Violle, Cyrille; Wiser, Susan K; Dolins, Steven; Donoghue, John C; Kraft, Nathan J B; Regetz, Jim; Schildhauer, Mark; Spencer, Nick; Svenning, Jens-Christian

    2013-12-01

    Despite being a fundamental aspect of biodiversity, little is known about what controls species range sizes. This is especially the case for hyperdiverse organisms such as plants. We use the largest botanical data set assembled to date to quantify geographical variation in range size for ~ 85 000 plant species across the New World. We assess prominent hypothesised range-size controls, finding that plant range sizes are codetermined by habitat area and long- and short-term climate stability. Strong short- and long-term climate instability in large parts of North America, including past glaciations, are associated with broad-ranged species. In contrast, small habitat areas and a stable climate characterise areas with high concentrations of small-ranged species in the Andes, Central America and the Brazilian Atlantic Rainforest region. The joint roles of area and climate stability strengthen concerns over the potential effects of future climate change and habitat loss on biodiversity.

  7. Habitat area and climate stability determine geographical variation in plant species range sizes

    DEFF Research Database (Denmark)

    Morueta-Holme, Naia; Enquist, Brian J.; McGill, Brian J.

    2013-01-01

    Despite being a fundamental aspect of biodiversity, little is known about what controls species range sizes. This is especially the case for hyperdiverse organisms such as plants. We use the largest botanical data set assembled to date to quantify geographical variation in range size for ~85,000 ...... concerns over the potential effects of future climate change and habitat loss on biodiversity.......,000 plant species across the New World. We assess prominent hypothesised range-size controls, finding that plant range sizes are codetermined by habitat area and long- and short-term climate stability. Strong short- and long-term climate instability in large parts of North America, including past...... glaciations, are associated with broad-ranged species. In contrast, small habitat areas and a stable climate characterise areas with high concentrations of small-ranged species in the Andes, Central America and the Brazilian Atlantic Rainforest region. The joint roles of area and climate stability strengthen...

  8. Stability and succession of the rhizosphere microbiota depends upon plant type and soil composition.

    Science.gov (United States)

    Tkacz, Andrzej; Cheema, Jitender; Chandra, Govind; Grant, Alastair; Poole, Philip S

    2015-11-01

    We examined succession of the rhizosphere microbiota of three model plants (Arabidopsis, Medicago and Brachypodium) in compost and sand and three crops (Brassica, Pisum and Triticum) in compost alone. We used serial inoculation of 24 independent replicate microcosms over three plant generations for each plant/soil combination. Stochastic variation between replicates was surprisingly weak and by the third generation, replicate microcosms for each plant had communities that were very similar to each other but different to those of other plants or unplanted soil. Microbiota diversity remained high in compost, but declined drastically in sand, with bacterial opportunists and putative autotrophs becoming dominant. These dramatic differences indicate that many microbes cannot thrive on plant exudates alone and presumably also require carbon sources and/or nutrients from soil. Arabidopsis had the weakest influence on its microbiota and in compost replicate microcosms converged on three alternative community compositions rather than a single distinctive community. Organisms selected in rhizospheres can have positive or negative effects. Two abundant bacteria are shown to promote plant growth, but in Brassica the pathogen Olpidium brassicae came to dominate the fungal community. So plants exert strong selection on the rhizosphere microbiota but soil composition is critical to its stability. microbial succession/ plant-microbe interactions/rhizosphere microbiota/selection.

  9. Environmental risk assessment for plant pests: a procedure to evaluate their impacts on ecosystem services

    DEFF Research Database (Denmark)

    Gilioli, G.; Schrader, G.; Baker, R.H.A.;

    2014-01-01

    . By including both the structural and functional components of the environment threatened by invasive alien species (IAS), in particular plant pests, we propose an environmental risk assessment scheme that addresses this complexity. Structural components are investigated by evaluating the impacts of the plant...

  10. The effect of mercury deposition to ecosystem around coal-power plants in Tan-An peninsular, S. Korea

    Science.gov (United States)

    Kim, Y.; Lee, J.; Song, K.; Shin, S.; Han, J.; Hong, E.; Jung, G.

    2009-12-01

    According to UNEP’s Report in 2008, Korea is one of the largest mercury emitting country with emission amount of 32 tones and the contribution of stationary coal combustion is estimated around 59%, as one of major mercury emission sources. There are growing needs of ecosystem mercury monitoring to evaluate the effectiveness on mercury emission controls by regulations. Thus, the aim of this study was to identify the useful monitoring indicators by comparing mercury levels of various environmental matrices in different ecosystems. Tae-an coal power plant, located on the west coastal of Korea is selected for study sites since it is one of the largest coal power plant in Korea with 4000 MW capacities. We chose 2 reservoirs near to Tae-an coal power plant and 2 others in An-myeon and Baeg-ryeong island for control study. Total gaseous mercury of ambient air was 3.6, 4.5 and 1.2 ng/m3 for Tae-an, An-myeon and Baeg-ryeong sites, respectively. From these results, we investigated and compared total mercury and methylmercury concentrations in surface water, soil, sediment, leaves and freshwater fish between reservoirs, which were known for the indicators of mercury atmospheric deposition. Estimates for the potential rates of methylation and activities of sulfur reducing bacteria were also made by injection radioactive isotopes of 203Hg and 35S. Potential methylation rate and acid volatile sulfide formation potential were dramatically changed by depth and maximum values were found in the top sediment section.

  11. The influence of competition between plant functional types in the Canadian Terrestrial Ecosystem Model (CTEM) v. 2.0

    Science.gov (United States)

    Melton, Joe; Arora, Vivek

    2015-04-01

    The Canadian Terrestrial Ecosystem Model (CTEM) is the interactive vegetation component in the earth system modelling framework of the Canadian Centre for Climate Modelling and Analysis (CCCma). In its current framework, CTEM uses prescribed fractional coverage of plant functional types (PFTs) in each grid cell. In reality, vegetation cover is continually adjusting to changes in climate, atmospheric composition, and anthropogenic forcing, for example, through human-caused fires and CO2 fertilization. These changes in vegetation spatial patterns occur over timescales of years to centuries as tree migration is a slow process and vegetation distributions inherently have inertia. Here, we present version 2.0 of CTEM that includes a representation of competition between PFTs through a modified version of the Lotka-Volterra (L-V) predator-prey equations. The simulated areal extents of CTEM's seven non-crop PFTs are compared with available observation-based estimates, and simulations using unmodified L-V equations (similar to other models like TRIFFID), to demonstrate that the model is able to represent the broad spatial distributions of its seven PFTs at the global scale. Differences remain, however, since representing the multitude of plant species with just seven non-crop PFTs only allows the large scale climatic controls on the distributions of PFTs to be captured. As expected, PFTs that exist in climate niches are difficult to represent either due to the coarse spatial resolution of the model and the corresponding driving climate or the limited number of PFTs used to model the terrestrial ecosystem processes. The geographic and zonal distributions of primary terrestrial carbon pools and fluxes from the versions of CTEM that use prescribed and dynamically simulated fractional coverage of PFTs compare reasonably with each other and observation-based estimates. These results illustrate that the parametrization of competition between PFTs in CTEM behaves in a reasonably

  12. Nitrogen deposition reduces plant diversity and alters ecosystem functioning: field-scale evidence from a nationwide survey of UK heathlands.

    Directory of Open Access Journals (Sweden)

    Georgina E Southon

    Full Text Available Findings from nitrogen (N manipulation studies have provided strong evidence of the detrimental impacts of elevated N deposition on the structure and functioning of heathland ecosystems. Few studies, however, have sought to establish whether experimentally observed responses are also apparent under natural, field conditions. This paper presents the findings of a nationwide field-scale evaluation of British heathlands, across broad geographical, climatic and pollution gradients. Fifty two heathlands were selected across an N deposition gradient of 5.9 to 32.4 kg ha(-1 yr(-1. The diversity and abundance of higher and lower plants and a suite of biogeochemical measures were evaluated in relation to climate and N deposition indices. Plant species richness declined with increasing temperature and N deposition, and the abundance of nitrophilous species increased with increasing N. Relationships were broadly similar between upland and lowland sites, with the biggest reductions in species number associated with increasing N inputs at the low end of the deposition range. Both oxidised and reduced forms of N were associated with species declines, although reduced N appears to be a stronger driver of species loss at the functional group level. Plant and soil biochemical indices were related to temperature, rainfall and N deposition. Litter C:N ratios and enzyme (phenol-oxidase and phosphomonoesterase activities had the strongest relationships with site N inputs and appear to represent reliable field indicators of N deposition. This study provides strong, field-scale evidence of links between N deposition--in both oxidised and reduced forms--and widespread changes in the composition, diversity and functioning of British heathlands. The similarity of relationships between upland and lowland environments, across broad spatial and climatic gradients, highlights the ubiquity of relationships with N, and suggests that N deposition is contributing to biodiversity

  13. A Review On Dump Slope Stabilization By Revegetation With Reference To Indigenous Plant

    Directory of Open Access Journals (Sweden)

    Vibhash Ranjan

    2015-08-01

    Full Text Available Abstract The waste sub-grade ROM and Fines dumps are characterized by high rock fragment contents low moisture retention capacity higher bulk density low nutrients lower pH and elevated metal concentrations. Use of suitable revegetation programme that require the selection of right type of plants to be used vis--vis the site condition and characteristics can enhance the long term stability both mechanical and ecological of dumps waste sub-grade ROM and fines through providing vegetative cover to control soil erosion amp gully formation consolidation of dump top amp side surfaces binding the loose particles through intricate roof system etc. This paper overviews the roles of Revegetation programme that can be used where vegetation is considered to be the long term answer to slope protection and erosion control. Various revegetation processes like Coir matting Lemmon Grass Vetiver Grass and Indigenous plant etc. may find a wide range of usage in Iron ore mines for dump stabilization.Miyawaki method of plantation is more effective than the conventional method of plantation. This will lead to co-existence of plants and as a matter of fact each plant draws from the other vital nutrients and they grow to become strong and healthy. The Miyawaki Plantation technique aim at Survival at fittest the area undergone such plantation have an ecology of their own. The Indigenous Plant has good binding capacity and helps to control soil erosion as well as improve the dump stability. Indigenous plant species like as Shorea robusta Sal CROTON ROXBURGHII Dal-bergia Sisoo SHISHAM KARANJ Azadirachta NEEM etc. The growth of indigenous plants is depending upon the soil quality as well as the organic matter of the dump material. The leaf debris plays important role for improving the organic matter of dump material for successfully implementation of revegetation programme.

  14. Roles of arbuscular mycorrhizas in plant nutrition and growth: new paradigms from cellular to ecosystem scales.

    Science.gov (United States)

    Smith, Sally E; Smith, F Andrew

    2011-01-01

    Root systems of most land plants form arbuscular mycorrhizal (AM) symbioses in the field, and these contribute to nutrient uptake. AM roots have two pathways for nutrient absorption, directly through the root epidermis and root hairs and via AM fungal hyphae into root cortical cells, where arbuscules or hyphal coils provide symbiotic interfaces. New physiological and molecular evidence shows that for phosphorus the mycorrhizal pathway (MP) is operational regardless of plant growth responses (positive or negative). Amounts delivered cannot be determined from plant nutrient contents because when responses are negative the contribution of the direct pathway (DP) is reduced. Nitrogen (N) is also delivered to roots via an MP, but the contribution to total N requirement and the costs to the plant are not clear. The functional interplay between activities of the DP and MP has important implications for consideration of AM symbioses in ecological, agronomic, and evolutionary contexts.

  15. Fluidic origami with embedded pressure dependent multi-stability: a plant inspired innovation.

    Science.gov (United States)

    Li, Suyi; Wang, K W

    2015-10-06

    Inspired by the impulsive movements in plants, this research investigates the physics of a novel fluidic origami concept for its pressure-dependent multi-stability. In this innovation, fluid-filled tubular cells are synthesized by integrating different Miura-Ori sheets into a three-dimensional topological system, where the internal pressures are strategically controlled similar to the motor cells in plants. Fluidic origami incorporates two crucial physiological features observed in nature: one is distributed, pressurized cellular organization, and the other is embedded multi-stability. For a single fluidic origami cell, two stable folding configurations can coexist due to the nonlinear relationships among folding, crease material deformation and internal volume change. When multiple origami cells are integrated, additional multi-stability characteristics could occur via the interactions between pressurized cells. Changes in the fluid pressure can tailor the existence and shapes of these stable folding configurations. As a result, fluidic origami can switch between being mono-stable, bistable and multi-stable with pressure control, and provide a rapid 'snap-through' type of shape change based on the similar principles as in plants. The outcomes of this research could lead to the development of new adaptive materials or structures, and provide insights for future plant physiology studies at the cellular level.

  16. Fluidic origami with embedded pressure dependent multi-stability: a plant inspired innovation

    Science.gov (United States)

    Li, Suyi; Wang, K. W.

    2015-01-01

    Inspired by the impulsive movements in plants, this research investigates the physics of a novel fluidic origami concept for its pressure-dependent multi-stability. In this innovation, fluid-filled tubular cells are synthesized by integrating different Miura-Ori sheets into a three-dimensional topological system, where the internal pressures are strategically controlled similar to the motor cells in plants. Fluidic origami incorporates two crucial physiological features observed in nature: one is distributed, pressurized cellular organization, and the other is embedded multi-stability. For a single fluidic origami cell, two stable folding configurations can coexist due to the nonlinear relationships among folding, crease material deformation and internal volume change. When multiple origami cells are integrated, additional multi-stability characteristics could occur via the interactions between pressurized cells. Changes in the fluid pressure can tailor the existence and shapes of these stable folding configurations. As a result, fluidic origami can switch between being mono-stable, bistable and multi-stable with pressure control, and provide a rapid ‘snap-through’ type of shape change based on the similar principles as in plants. The outcomes of this research could lead to the development of new adaptive materials or structures, and provide insights for future plant physiology studies at the cellular level. PMID:26400197

  17. A coupled carbon and plant hydraulic model to predict ecosystem carbon and water flux responses to disturbance and environmental change

    Science.gov (United States)

    Mackay, D. S.; Ewers, B. E.; Roberts, D. E.; McDowell, N. G.; Pendall, E.; Frank, J. M.; Reed, D. E.; Massman, W. J.; Mitra, B.

    2011-12-01

    Changing climate drivers including temperature, humidity, precipitation, and carbon dioxide (CO2) concentrations directly control land surface exchanges of CO2 and water. In a profound way these responses are modulated by disturbances that are driven by or exacerbated by climate change. Predicting these changes is challenging given that the feedbacks between environmental controls, disturbances, and fluxes are complex. Flux data in areas of bark beetle outbreaks in the western U.S.A. show differential declines in carbon and water flux in response to the occlusion of xylem by associated fungi. For example, bark beetle infestation at the GLEES AmeriFlux site manifested in a decline in summer water use efficiency to 60% in the year after peak infestation compared to previous years, and no recovery of carbon uptake following a period of high vapor pressure deficit. This points to complex feedbacks between disturbance and differential ecosystem reaction and relaxation responses. Theory based on plant hydraulics and extending to include links to carbon storage and exhaustion has potential for explaining these dynamics with simple, yet rigorous models. In this spirit we developed a coupled model that combines an existing model of canopy water and carbon flow, TREES [e.g., Loranty et al., 2010], with the Sperry et al., [1998] plant hydraulic model. The new model simultaneously solves carbon uptake and losses along with plant hydraulics, and allows for testing specific hypotheses on feedbacks between xylem dysfunction, stomatal and non-stomatal controls on photosynthesis and carbon allocation, and autotrophic and heterotrophic respiration. These are constrained through gas exchange, root vulnerability to cavitation, sap flux, and eddy covariance data in a novel model complexity-testing framework. Our analysis focuses on an ecosystem gradient spanning sagebrush to subalpine forests. Our modeling results support hypotheses on feedbacks between hydraulic dysfunction and 1) non

  18. Rare and Endemic Plants in the Southern Mountain Ecosystems of Albania, their Threats and Diversity

    Directory of Open Access Journals (Sweden)

    ERMELINDA MAHMUTAJ

    2015-03-01

    Full Text Available The study highlights flora and vegetation richness in the mountain ecosystems in Southern Albania, focusing mainly on Çika, Këndërvica, and Tomorri Mts. The data are collected in more than 100 relevés during field trips, carried out in periods of intensive vegetation. It shows the presence of 11 endemic taxa, 23 nearendemics and more than 60 Balkan endemics. Two new species for science are described recently (Gymnospermium maloi Kit Tan & Shuka and Campanula aureliana Bogdanović, Rešetnik, Brullo & Shuka and some others are confirmed about 100 years after (Sesleria albanica Ujhelyi and Stachys sericophylla Halacsy. Main threats, especially for the endemics and rare taxa of the southern region of Albania, are presented in this study, with recommendations for future steps. Some Natura2000 habitats are identified and a relevance of different habitat types like EUNIS, and Syntaxonomic classifications are linked together. The main aim of this study was the identification and presentation of floristic and vegetation values of this wide natural ecosystem and putting them into the function of science. The results indicate the area as the richest in the country, due to the insignificant influence of human factor and diversity of climate and terrestrial elements.

  19. Water sources of plants and groundwater in typical ecosystems in the lower reaches of the Heihe River Basin

    Institute of Scientific and Technical Information of China (English)

    YunFeng Ruan; LiangJu Zhao; HongLang Xiao; GuoDong Cheng; MaoXian Zhou; Fang Wang

    2014-01-01

    Stable oxygen and hydrogen isotopic compositions (δ18O andδD) of soil water and shallow groundwater of a riparian forest, an artificial shrub forest, and Gobi of the lower reaches of the Heihe River Basin are used to study the recharge water sources of those ecosystems. IsoSource software is used to determine theδ18O values for root water of Populous euphratica and Tamarix ramosissima in the riparian forest ecosystem, Haloxylon ammodendron in the artificial shrub forest, and Reaumuria soongorica in the Gobi, as well as for local soil water and groundwater, and precipitation in the upper reaches of the Heihe River Basin. Our results showed that soil water and shallow groundwater of the riparian forest and the artificial shrub forest were recharged by river water which originated from precipitation in the upper reaches, and strong evaporation occurred in the artificial shrub forest. Soil water of the Gobi was not affected by Heihe River water due to this area being far away from the river channel. The main water sources of Populous euphratica were from 40-60-cm soil water and groundwater, and of Tamarix ramosissima were from 40-80-cm soil water in the riparian forest ecosystem. In the artificial forest, Haloxylon ammodendron used 200-cm saturated-layer soil water and shallow groundwater. The Reaumuria soongorica mainly used soil water from the 175-200-cm depth in the Gobi. Therefore, soil water and groundwater are the main water sources which maintain survival and growth of the plants in the extremely arid regions of the lower reaches of the Heihe River Basin.

  20. Both temperature fluctuations and East Asian monsoons have driven plant diversification in the karst ecosystems from southern China.

    Science.gov (United States)

    Kong, Hanghui; Condamine, Fabien L; Harris, A J; Chen, Junlin; Pan, Bo; Möller, Michael; Hoang, Van Sam; Kang, Ming

    2017-09-28

    Karst ecosystems in southern China are species-rich and have high levels of endemism, yet little is known regarding the evolutionary processes responsible for the origin and diversification of karst biodiversity. The genus Primulina (Gesneriaceae) comprises ca. 170 species endemic to southern China with high levels of ecological (edaphic) specialization, providing an exceptional model to study the plant diversification in karsts. We used molecular data from nine chloroplast and 11 nuclear regions and macroevolutionary analyses to assess the origin and cause of species diversification due to paleoenvironmental changes and edaphic specialization in Primulina. We found that speciation was positively associated with changes in past temperatures and East Asian monsoons through the evolutionary history of Primulina. Climatic change around the mid-Miocene triggered an early burst followed by a slowdown of diversification rate towards the present with the climate cooling. We detected different speciation rates among edaphic types, and transitions among soil types were infrequently and did not impact the overall speciation rate. Our findings suggest that both global temperature changes and East Asian monsoons have played crucial roles in floristic diversification within the karst ecosystems in southern China, such that speciation was higher when climate was warmer and wetter. This is the first study to directly demonstrate that past monsoon activity is positively correlated with speciation rate in East Asia. This case study could motivate further investigations to assess the impacts of past environmental changes on the origin and diversification of biodiversity in global karst ecosystems, most of which are under threat. This article is protected by copyright. All rights reserved. This article is protected by copyright. All rights reserved.

  1. Attenuation of pharmaceuticals and their transformation products in a wastewater treatment plant and its receiving river ecosystem.

    Science.gov (United States)

    Aymerich, I; Acuña, V; Barceló, D; García, M J; Petrovic, M; Poch, M; Rodriguez-Mozaz, S; Rodríguez-Roda, I; Sabater, S; von Schiller, D; Corominas, Ll

    2016-09-01

    Pharmaceuticals are designed to improve human and animal health, but may also be a threat to freshwater ecosystems, particularly after receiving urban or wastewater treatment plant (WWTP) effluents. Knowledge on the fate and attenuation of pharmaceuticals in engineered and natural ecosystems is rather fragmented, and comparable methods are needed to facilitate the comprehension of those processes amongst systems. In this study the dynamics of 8 pharmaceuticals (acetaminophen, sulfapyridine, sulfamethoxazole, carbamazepine, venlafaxine, ibuprofen, diclofenac, diazepam) and 11 of their transformation products were investigated in a WWTP and the associated receiving river ecosystem. During 3 days, concentrations of these compounds were quantified at the influents, effluents, and wastage of the WWTP, and at different distances downstream the effluent at the river. Attenuation (net balance between removal and release from and to the water column) was estimated in both engineered and natural systems using a comparable model-based approach by considering different uncertainty sources (e.g. chemical analysis, sampling, and flow measurements). Results showed that pharmaceuticals load reduction was higher in the WWTP, but attenuation efficiencies (as half-life times) were higher in the river. In particular, the load of only 5 out of the 19 pharmaceuticals was reduced by more than 90% at the WWTP, while the rest were only partially or non-attenuated (or released) and discharged into the receiving river. At the river, only the load of ibuprofen was reduced by more than 50% (out of the 6 parent compounds present in the river), while partial and non-attenuation (or release) was observed for some of their transformation products. Linkages in the routing of some pharmaceuticals (venlafaxine, carbamazepine, ibuprofen and diclofenac) and their corresponding transformation products were also identified at both WWTP and river. Finally, the followed procedure showed that dynamic

  2. Impact of global climate change on ecosystem-level interactions among sympatric plants from all three photosynthetic pathways. Terminal report

    Energy Technology Data Exchange (ETDEWEB)

    Nobel, P.S.

    1997-12-17

    The proposed research will determine biochemical and physiological responses to variations in environmental factors for plants of all three photosynthetic pathways under competitive situations in the field. These responses will be used to predict the effects of global climatic change on an ecosystem in the northwestern Sonoran Desert where the C{sub 3} subshrub Encelia farinosa, the C{sub 4} bunchgrass Hilaria rigida, and the CAM succulent Agave deserti are co-dominants. These perennials are relatively short with overlapping shallow roots facilitating the experimental measurements as well as leading to competition for soil water. Net CO{sub 2} uptake over 24-h periods measured in the laboratory will be analyzed using an environmental productivity index (EPI) that can incorporate simultaneous effects of soil water, air temperature, and light. Based on EPI, net CO{sub 2} uptake and hence plant productivity will be predicted for the three species in the field under various treatments. Activity of the two CO{sub 2} fixation enzymes, Rubisco and PEPCase, will be determined for these various environmental conditions; also, partitioning of carbon to various organs will be measured based on {sup 14}CO{sub 2} labeling and dry weight analysis. Thus, enzymatic and partitioning controls on competition among sympatric model plants representing all three photosynthetic pathways will be investigated.

  3. Lotic aquatic ecosystems of the Savannah River Plant: Impact evaluation, habitat analyses and the lower food chain communities: Volume 1

    Energy Technology Data Exchange (ETDEWEB)

    Firth, P.; O' Hop, J.R.; Coler, B.; Green, R.A.

    1986-04-01

    This report documents a study of animal habitat and the lower food chain communities in the streams and swamps of the Savannah River Plant (SRP). The purpose of the study was to assess the impacts of SRP operations on the lotic (flowing water) ecosystems on the plant site and on portions of the Savannah River. The 1985 survey year included the period between 1 October 1984 and 30 September 1985. Forty-seven stations located on five drainage basins within the SRP boundaries and on the Savannah River were sampled. The drainage basins were: Upper Three Runs Creek (3 sites), Beaver Dam Creek-Four Mile Creek (5 and 7 sites, respectively), Pen Branch (5 sites), Steel Creek-Meyers Branch system (12 and 2 sites, respectively), and Lower Three Runs Creek (5 sites). The remaining eight sites were on the Savannah River, upstream and downstream of creek mouths. Fifteen of the sites were thermal due to heated effluents from D-area power plant (discharging to Beaver Dam Creek), C-reactor (discharging to Four Mile Creek), or K-reactor (discharging to Pen Branch). 224 refs., 20 figs., 131 tabs.

  4. Genetic stability of micropropagated plants of Crambe abyssinica Hochst using ISSR markers.

    Science.gov (United States)

    Werner, E T; Soares, T C B; Gontijo, A B P L; Souza Neto, J D; do Amaral, J A T

    2015-12-09

    Crambe (Crambe abyssinica) is a non-edible annual herb, which was first cultivated to extract oil for industry, and now has great potential for biodiesel production. The objective of this investigation was to evaluate the genetic stability of micropropagated plants of the C. abyssinica Hochst cultivar 'FMS brilhante' using polymerase chain reaction techniques based on inter-simple sequence repeat (ISSR) molecular markers. The aim was to develop a protocol for the in vitro regeneration of these plants with low genetic variation as compared to the donor plant. For micropropagation, shoot tips from in vitro germinated seedlings were used as explants and were initially cultivated for 90 days on MS medium with 5.0 μM 6-benzylaminopurine (BAP), which at 90 days, led to the highest number of shoots per explant (NSE) (12.20 shoots) being detected. After 120 days, the interaction between BAP concentration and naphthalene acetic acid (NAA) was tested, and the highest NSE was observed following exposure to 0.0/0.5 μM BAP/NAA (11.40 shoots) and 1.0/0.0 μM BAP/NAA (11.00 shoots). The highest proportion of rooting phase were observed following exposure to 0.5 μM NAA (30%). The 13 ISSR primers used to analyze genetic stability produced 91 amplification products, of which only eight bands were polymorphic and 83 were monomorphic for all 10 regenerated crambe plants, compared to the donor plant explant. These results indicate that crambe shoot tips are a highly reliable explant that can be used to micropropagate genetically true-to-type plants or to maintain genetic stability, as verified using ISSR markers.

  5. Ecosystem-Based Incorporation of Nectar-Producing Plants for Stink Bug Parasitoids

    Directory of Open Access Journals (Sweden)

    Glynn Tillman

    2017-06-01

    Full Text Available Adult parasitoids of pest insects rely on floral resources for survival and reproduction, but can be food-deprived in intensively managed agricultural systems lacking these resources. Stink bugs are serious pests for crops in southwest Georgia. Provisioning nectar-producing plants for parasitoids of stink bugs potentially can enhance biocontrol of these pests. Knowledge of spatial and temporal availability and distribution of stink bugs in host plants is necessary for appropriate timing and placement of flowering plants in agroecosystems. Stink bugs move between closely associated host plants throughout the growing season in response to deteriorating suitability of their host plants. In peanut-cotton farmscapes, stink bugs develop in peanut, and subsequently the adults disperse into adjacent cotton. Parasitism of Nezara viridula (L. adults by Trichopoda pennipes (F. at the peanut-cotton interface was significantly higher in cotton with a strip of milkweed or buckwheat between the two crops than in cotton alone. Milkweed and buckwheat also provided nectar to a wide range of insect pollinators. Monarch butterflies fed on milkweed. When placed between peanut and cotton, a strip of soybean was an effective trap crop for cotton, reducing economic damage. Incorporation of buckwheat near soybean enhanced parasitism of Euschistus servus (Say eggs by Telenomus podisi Ashmead in cotton. In conclusion, nectar provision enhances biocontrol of stink bugs, acts together with other management tactics for stink bug control, and aids in conservation of natural enemies, insect pollinators, and the monarch butterfly.

  6. Ecosystem-Based Incorporation of Nectar-Producing Plants for Stink Bug Parasitoids.

    Science.gov (United States)

    Tillman, Glynn

    2017-06-24

    Adult parasitoids of pest insects rely on floral resources for survival and reproduction, but can be food-deprived in intensively managed agricultural systems lacking these resources. Stink bugs are serious pests for crops in southwest Georgia. Provisioning nectar-producing plants for parasitoids of stink bugs potentially can enhance biocontrol of these pests. Knowledge of spatial and temporal availability and distribution of stink bugs in host plants is necessary for appropriate timing and placement of flowering plants in agroecosystems. Stink bugs move between closely associated host plants throughout the growing season in response to deteriorating suitability of their host plants. In peanut-cotton farmscapes, stink bugs develop in peanut, and subsequently the adults disperse into adjacent cotton. Parasitism of Nezara viridula (L.) adults by Trichopoda pennipes (F.) at the peanut-cotton interface was significantly higher in cotton with a strip of milkweed or buckwheat between the two crops than in cotton alone. Milkweed and buckwheat also provided nectar to a wide range of insect pollinators. Monarch butterflies fed on milkweed. When placed between peanut and cotton, a strip of soybean was an effective trap crop for cotton, reducing economic damage. Incorporation of buckwheat near soybean enhanced parasitism of Euschistus servus (Say) eggs by Telenomus podisi Ashmead in cotton. In conclusion, nectar provision enhances biocontrol of stink bugs, acts together with other management tactics for stink bug control, and aids in conservation of natural enemies, insect pollinators, and the monarch butterfly.

  7. Stability Analysis of DC-link Voltage Control on Autonomous Micro Hydro Power Plant System

    Directory of Open Access Journals (Sweden)

    Feri Yusivar

    2014-12-01

    Full Text Available Micro Hydro Power Plant has become one of the interesting topics to be researched nowadays. This paper deals with the stability analysis on control system of excitation voltage in Micro Hydro Power Plant. The control of this voltage can be achieved by controlling the Permanent Magnet Synchronous Machine (PMSM with particular algorithm so the voltage on the DC-link part of the system can be controlled. Without knowing the exact specification of system parameters, the system will be most likely unstable. The DC-link control system is modeled, simulated, and mathematically analyzed so the parameter specification for the stable system can be obtained.

  8. 云南大中山黑颈长尾雉栖境生态系统稳定性%On Habitat Ecosystem Stability of Hume's Pheasant (Syrmaticus humiae) at Dazhong Mountain of Yunnan Province

    Institute of Scientific and Technical Information of China (English)

    周伟; 刘钊; 邓忠坚

    2011-01-01

    The ecosystem stability of foraging habitat of Hume's Pheasant(Syrmaticus humiae) in Dazhong Mountain Nature Reserve, Yunnan Province was synthetically analyzed, based on evaluating the data reflecting ecosystem stability and habitat suitability. The results showed that the ecosystem of Dazhong Mountain Nature Reserve could be divided into five different types of stability zones, including the most stable, stable, relatively stable, in-stable and the most instable areas. The potential and actual habitats of Hume's Pheasant mainly distributed in the most stable, stable and relatively stable areas on the eastern slop, whereas less distributed in the instable and the most instable areas. This distribution pattern reduced the ecological risks from the suitability degradation caused by environmental fluctuation. There was a significant difference in proportion between the potential and actual habitat areas in the instable area of the ecosystem, and the actual habitat areas was significantly reduced with decline of the ecosystem stability. Human disturbance degraded the ecosystem stability in some parts of the reserve, as well as influenced upon the utilization of potential habitat and reduced the actual habitat area for Hume's Pheasant. The ecological factors involved in evaluating the ecosystem stability only reflected the attribute of stability rather than habitat requirement by Hume's Pheasant. The preference choosing habitat ecosystem with higher stability by Hume's Pheasant was the result from adapting the environment passively. The plant diversity was high in the foraging habitat of Hume's Pheasant so that it could provide the bird with abundant food for its survival. The relationship between animal and environment with the addition of higher species diversity was conductive to the formation and maintenance of the ecosystem stability.%以生态系统稳定性和生境适宜性评价数据为基础,综合分析云南大中山黑颈长尾雉觅食生境的生态系

  9. Accumulation and transfer of 137Cs and 90Sr in the plants of the forest ecosystem near the Ignalina Nuclear Power Plant.

    Science.gov (United States)

    Lukšienė, B; Marčiulionienė, D; Gudelienė, I; Schönhofer, F

    2013-02-01

    The radioecological state of the forest ecosystem in the vicinity of the Ignalina Power Plant prior to decommissioning was analysed with specific emphasis on (137)Cs and (90)Sr activity concentrations in plant species growing in two reference sampling sites (Tilze and Grikiniskes). In the period of 1996-2008 the mean contamination of plants with (137)Cs was from 45 to 119 Bq/kg and with (90)Sr - from 3 to 42 Bq/kg. Measured (137)Cs TF values for soil-root transfer mainly ranged between 1.0-1.4, except for Calamagrostis arundinacea which had a TF value of 0.1. On average, the (137)Cs TF value from root to shoot was 1.7 fold higher than for soil to root transfer. (90)Sr TF values (soil-root) were in the range of 1.2-1.8 but for Calluna vulgaris it was 0.2. The mean root to shoot TF value for (90)Sr was 7.7 fold higher. These results indicate the higher (90)Sr bioavailability than that of (137)Cs in the forested area. The Grikiniskes reference site is located nearby the Ignalina NPP, specifically the heated water outlet channel, which results in altered microclimatic conditions. These specific microclimatic conditions result in relationships between (137)Cs TF (soil-root) values and pH, moisture and organic matter content in the soil at Grikiniskes which appear to be different to those at the Tilze reference sampling site.

  10. Biomass burning in boreal forests and peatlands: Effects on ecosystem carbon losses and soil carbon stabilization as black carbon

    Science.gov (United States)

    Turetsky, M. R.; Kane, E. S.; Benscoter, B.

    2011-12-01

    Climate change has increased both annual area burned and the severity of biomass combustion in some boreal regions. For example, there has been a four-fold increase in late season fires in boreal Alaska over the last decade relative to the previous 50 years. Such changes in the fire regime are expected to stimulate ecosystem carbon losses through fuel combustion, reduced primary production, and increased decomposition. However, biomass burning also will influence the accumulation of black carbon in soils, which could promote long-term soil carbon sequestration. Variations in slope and aspect regulate soil temperatures and drainage conditions, and affect the development of permafrost and thick peat layers. Wet soil conditions in peatlands and permafrost forests often inhibit combustion during wildfires, leading to strong positive correlations between pre- and post- fire organic soil thickness that persist through multiple fire cycles. However, burning can occur in poorly drained ecosystems through smouldering combustion, which has implications for emission ratios of CO2:CH4:CO as well as black carbon formation. Our studies of combustion severity and black carbon concentrations in boreal soils show a negative relationship between concentrations of black carbon and organic carbon in soils post-fire. Relative to well drained stands, poorly drained sites with thick peat layers (such as north-facing stands) had less severe burning and low concentrations of black carbon in mineral soils post-fire. Conversely, drier forests lost a greater proportion of their organic soils during combustion but retained larger black carbon stocks following burning. Overall, we have quantified greater black carbon concentrations in surface mineral soil horizons than in organic soil horizons. This is surprising given that wildfires typically do not consume the entire organic soil layer in boreal forests, and could be indicative of the vulnerability of black carbon formed in organic horizons

  11. Assessment of genetic stability in micropropagated plants of some ornamental strawberry varieties

    Directory of Open Access Journals (Sweden)

    Anca Nicoleta Şuţan

    2012-12-01

    Full Text Available In order to evaluate the genetic stability and uniformity of ornamental strawberry plants micropropagated by using a new and highly efficient protocol we have developed recently, RAPD markers were used with intergeneric hybrids ‘Pink Panda’ and ‘Serenata’. Micropropagated shoots selected at random from four subcultures onto either Murashige & Skoog or Lee & Fossard media, each of them supplemented with 6-benzylaminopurine (BAP at 1.0 mg l-1, indolylacetic acid (IAA at 1.0 mg l-1 and gibberellic acid (GA3 at 0.1mg l-1, were subjected to molecular analysis. Ten deca-nucleotide primers (among 48 tested were chosen for RAPD analysis, all of them indicating genetic stability for micropropagated plants of the investigated varieties of ornamental strawberry.

  12. Optimization and stabilization of gold nanoparticles by using herbal plant extract with microwave heating

    Science.gov (United States)

    Yasmin, Akbar; Ramesh, Kumaraswamy; Rajeshkumar, Shanmugam

    2014-04-01

    In this study, we have synthesized the gold nanoparticles by using Hibiscus rosa-sinensis, a medicinal plant. The gold nanoparticles were synthesized rapidly by the involvement of microwave heating. By changing of plant extract concentration, gold solution concentration, microwave heating time and power of microwave heating the optimized condition was identified. The surface Plasmon resonance found at 520 nm confirmed the gold nanoparticles synthesis. The spherical sized nanoparticles in the size range of 16-30 nm were confirmed by Transmission Electron Microscope (TEM). The stability of the nanoparticles is very well proved in the invitro stability tests. The biochemical like alkaloids and flavonoids play a vital role in the nanoparticles synthesis was identified using the Fourier Transform Infrared Spectroscopy (FTIR). Combining the phytochemical and microwave heating, the rapid synthesis of gold nanoparticles is the novel process for the medically applicable gold nanoparticles production.

  13. Ecosystem responses to warming-induced plant species loss and increased nitrogen availability in a Rocky Mountain subalpine meadow

    Science.gov (United States)

    Smith, Molly Elizabeth

    Climate change is predicted to be an important driver of future biodiversity changes, especially in mountainous environments. Climate warming-induced plant species loss is likely to be non-random and based on species-specific susceptibility to rising temperatures. Experimental warming results from a subalpine meadow in Colorado suggest that warming adversely affects shallow-rooted forb species in this ecosystem. To examine the ecological consequences of losing this warming-sensitive species group, I experimentally removed all shallow-rooted forb species from otherwise intact subalpine meadow plots. Since experimental warming also resulted in increased soil nitrogen availability, I crossed the removal treatment with a nitrogen addition treatment to determine whether the loss of shallow-rooted forbs altered the community's response to a perturbation in nitrogen availability. After three years of experimental species removal, tap-rooted forbs and grasses were able to fully compensate for the loss of shallow-rooted forbs with increased biomass production. Moreover, the remaining plant community yielded a larger biomass response to nitrogen addition when shallow-rooted forbs were removed, possibly because removal led to increased soil moisture. The loss of shallow-rooted forbs and addition of nitrogen did not have strong effects on nitrogen cycling beyond increases in the amount of nitrate moving down through the soil profile. Uptake of nitrogen into plant tissue was also not affected by either the shallow-rooted forb removal or nitrogen addition treatments, suggesting that nitrogen may not have been the most limiting resource during the experiment. I found that spatial heterogeneity generally had a greater influence on soil microbial community composition than any of the experimental treatments. I conclude that the warming-induced loss of shallow-rooted forbs did not affect biomass production, nitrogen cycling, or soil microbial community composition, but did increase

  14. Modelling and Stability of a Single-Shaft Combined Cycle Power Plant

    Directory of Open Access Journals (Sweden)

    Costas Vournas

    2007-06-01

    Full Text Available The subject of this paper is the development of a dynamic model for a single-shaft combined cycle plant and the analysis of its response to electrical load and frequency transients. In particular the stability of the frequency control, as well as the implications of overheat control are investigated. The model is developed in the Simulink environment of Matlab as part of an educational and research simulation package for autonomous and interconnected systems.

  15. Proposed Methodology for Specifying Atrazine Levels of Concern for Protection of Plant Communities in Freshwater Ecosystems

    Science.gov (United States)

    This document describes a proposed methodology for setting levels of concern (LOCs) for atrazine in natural freshwater systems to prevent unacceptably adverse effects on the aquatic plant communities in those systems. LOCs regarding effects on humans and possible effects on amph...

  16. Climate Change Effects to Plant Ecosystems - Genetic Resources for Future Barley Breeding

    DEFF Research Database (Denmark)

    Ingvordsen, Cathrine Heinz

    were identified for possible use in breeding of climate resilient cultivars and SNP-markers that link to traits favourable in changed environments. Basic knowledge of plant response to multifactor climate treatments has been added as well as data on numerous genotypes modeling the impact of climate...

  17. Isotopes reveal contrasting water use strategies among coexisting plant species in a Mediterranean ecosystem.

    Science.gov (United States)

    Moreno-Gutiérrez, Cristina; Dawson, Todd E; Nicolás, Emilio; Querejeta, José Ignacio

    2012-10-01

    Variation in the stable carbon and oxygen isotope composition (δ13C, Δ18O) of co-occurring plant species may reflect the functional diversity of water use strategies present in natural plant communities. We investigated the patterns of water use among 10 coexisting plant species representing diverse taxonomic groups and life forms in semiarid southeast Spain by measuring their leaf δ13C and Δ18O, the oxygen isotope ratio of stem water and leaf gas exchange rates. Across species, Δ18O was tightly negatively correlated with stomatal conductance (gs), whereas δ13C was positively correlated with intrinsic water use efficiency (WUEi). Broad interspecific variation in Δ18O, δ13C and WUEi was largely determined by differences in gs, as indicated by a strong positive correlation between leaf δ13C and Δ18O across species The 10 co-occurring species segregated along a continuous ecophysiological gradient defined by their leaf δ13C and Δ18O, thus revealing a wide spectrum of stomatal regulation intensity and contrasting water use strategies ranging from 'profligate/opportunistic' (high gs, low WUEi) to 'conservative' (low gs, high WUEi). Coexisting species maintained their relative isotopic rankings in 2 yr with contrasting rainfall, suggesting the existence of species-specific 'isotopic niches' that reflect ecophysiological niche segregation in dryland plant communities. © 2012 The Authors. New Phytologist © 2012 New Phytologist Trust.

  18. Invasive alien plants in the terrestrial ecosystems of Natal, South Africa

    CSIR Research Space (South Africa)

    Macdonald, IAW

    1985-01-01

    Full Text Available This report consists of two types of chapters. Most of the chapters are short syntheses of particular aspects of the alien plant problem in Natal, written by groups of participants during the workshop meeting. They are brief accounts of the state...

  19. Proposed Methodology for Specifying Atrazine Levels of Concern for Protection of Plant Communities in Freshwater Ecosystems

    Science.gov (United States)

    This document describes a proposed methodology for setting levels of concern (LOCs) for atrazine in natural freshwater systems to prevent unacceptably adverse effects on the aquatic plant communities in those systems. LOCs regarding effects on humans and possible effects on amph...

  20. Nutrient dynamics and plant assemblages of Macrotermes falciger mounds in a savanna ecosystem

    Science.gov (United States)

    Muvengwi, Justice; Ndagurwa, Hilton G. T.; Nyenda, Tatenda; Mbiba, Monicah

    2016-10-01

    Termites through mound construction and foraging activities contribute significantly to carbon and nutrient fluxes in nutrient-poor savannas. Despite this recognition, studies on the influence of termite mounds on carbon and nitrogen dynamics in sub-tropical savannas are limited. In this regard, we examined soil nutrient concentrations, organic carbon and nitrogen mineralization in incubation experiments in mounds of Macrotermes falciger and surrounding soils of sub-tropical savanna, northeast Zimbabwe. We also addressed whether termite mounds altered the plant community and if effects were similar across functional groups i.e. grasses, forbs or woody plants. Mound soils had significantly higher silt and clay content, pH and concentrations of calcium (Ca), magnesium (Mg), potassium (K), organic carbon (C), ammonium (NH4+) and nitrate (NO3-) than surrounding soils, with marginal differences in phosphorus (P) and sodium (Na) between mounds and matrix soils. Nutrient enrichment increased by a factor ranging from 1.5 for C, 4.9 for Mg up to 10.3 for Ca. Although C mineralization, nitrification and nitrification fraction were similar between mounds and matrix soils, nitrogen mineralization was elevated on mounds relative to surrounding matrix soils. As a result, termite mounds supported unique plant communities rich and abundant in woody species but less diverse in grasses and forbs than the surrounding savanna matrix in response to mound-induced shifts in soil parameters specifically increased clay content, drainage and water availability, nutrient status and base cation (mainly Ca, Mg and Na) concentration. In conclusion, by altering soil properties such as texture, moisture content and nutrient status, termite mounds can alter the structure and composition of sub-tropical savanna plant communities, and these results are consistent with findings in other savanna systems suggesting that increase in soil clay content, nutrient status and associated changes in the plant

  1. A biome-scale assessment of the impact of invasive alien plants on ecosystem services in South Africa.

    Science.gov (United States)

    van Wilgen, B W; Reyers, B; Le Maitre, D C; Richardson, D M; Schonegevel, L

    2008-12-01

    This paper reports an assessment of the current and potential impacts of invasive alien plants on selected ecosystem services in South Africa. We used data on the current and potential future distribution of 56 invasive alien plant species to estimate their impact on four services (surface water runoff, groundwater recharge, livestock production and biodiversity) in five terrestrial biomes. The estimated reductions in surface water runoff as a result of current invasions were >3000 million m(3) (about 7% of the national total), most of which is from the fynbos (shrubland) and grassland biomes; the potential reductions would be more than eight times greater if invasive alien plants were to occupy the full extent of their potential range. Impacts on groundwater recharge would be less severe, potentially amounting to approximately 1.5% of the estimated maximum reductions in surface water runoff. Reductions in grazing capacity as a result of current levels of invasion amounted to just over 1% of the potential number of livestock that could be supported. However, future impacts could increase to 71%. A 'biodiversity intactness index' (the remaining proportion of pre-modern populations) ranged from 89% to 71% for the five biomes. With the exception of the fynbos biome, current invasions have almost no impact on biodiversity intactness. Under future levels of invasion, however, these intactness values decrease to around 30% for the savanna, fynbos and grassland biomes, but to even lower values (13% and 4%) for the two karoo biomes. Thus, while the current impacts of invasive alien plants are relatively low (with the exception of those on surface water runoff), the future impacts could be very high. While the errors in these estimates are likely to be substantial, the predicted impacts are sufficiently large to suggest that there is serious cause for concern.

  2. Silver or gold deposition onto magnetite nanoparticles by using plant extracts as reducing and stabilizing agents.

    Science.gov (United States)

    Norouz Dizaji, Araz; Yilmaz, Mehmet; Piskin, Erhan

    2016-06-01

    In this paper, we describe an environmentally friendly procedure to produce silver (Ag) or gold (Au)-deposited magnetite nanoparticles by using plant extracts (Ligustrum vulgare) as reducing and stabilizing agents. Firstly, magnetite nanoparticles (∼6 nm) with superparamagnetic properties - SPIONs - were synthesized by co-precipitation of Fe(+ 2) and Fe(+ 3) ions. Color changes indicated the differing amounts of Au and Ag ions reduced and deposited on to the SPIONs when the plant extracts were used. UV-vis and transmission electron microscope (TEM) with energy dispersive X-ray (EDX) apparatus confirmed the metallic deposition. Magnetic saturation decreased when the amount of the metallic deposition increased, which was measured by vibrating sample magnetometry (VSM). Due to the molecules coming into contact with - and even remaining on - the surface of the nanoparticles after aggressive washing procedures, the Ag/Au-deposited SPIONs were stable, and almost no agglomeration was observed for months. Fourier Transform Infrared (FTIR) spectra depicted that functional groups such as carboxylic and ketone groups, which are most probably responsible for the reduction and stabilization of Ag/Au- carrying magnetite nanoparticles, originated from the plant extract. The proposed route was facile, viable, and reproducible, and it should be stressed that nanoparticles do contain only safe biomolecules as stabilizing agents on their surfaces.

  3. Sludge stabilization at the Plutonium Finishing Plant, Hanford Site, Richland, Washington

    Energy Technology Data Exchange (ETDEWEB)

    1994-10-01

    This Environmental Assessment evaluates the proposed action to operate two laboratory-size muffle furnaces in glovebox HC-21C, located in the Plutonium Finishing Plant (PFP), Hanford Site, Richland, Washington. The muffle furnaces would be used to stabilize chemically reactive sludges that contain approximately 25 kilograms (55 pounds) of plutonium by heating to approximately 500 to 1000{degrees}C (900 to 1800{degrees}F). The resulting stable powder, mostly plutonium oxide with impurities, would be stored in the PFP vaults. The presence of chemically reactive plutonium-bearing sludges in the process gloveboxes poses a risk to workers from radiation exposure and limits the availability of storage space for future plant cleanup. Therefore, there is a need to stabilize the material into a form suitable for long-term storage. This proposed action would be an interim action, which would take place prior to completion of an Environmental Impact Statement for the PFP which would evaluate stabilization of all plutonium-bearing materials and cleanout of the facility. However, only 10 percent of the total quantity of plutonium in reactive materials is in the sludges, so this action will not limit the choice of reasonable alternatives or prejudice the Record of Decision of the Plutonium Finishing Plant Environmental Impact Statement.

  4. Characterization of Oxidative Stability of Fish Oil- and Plant Oil-Enriched Skimmed Milk

    DEFF Research Database (Denmark)

    Saga, Linda C.; Kristinova, Vera; Kirkhus, Bente

    2013-01-01

    The objective of this research was to determine the oxidative stability of fish oil blended with crude plant oils rich in naturally occurring antioxidants, camelina oil and oat oil, respectively, in bulk and after supplementation of 1 wt% of oil blends to skimmed milk emulsions. Ability of crude...... oat oil and camelina oil to protect fish oil in bulk and as fish oil-enriched skimmed milk emulsions was evaluated. Results of oxidative stability of bulk oils and blends assessed by the Schaal oven weight gain test and by the rancimat method showed significant increase in oxidative stability when oat......, skimmed milk supplemented with fish-oat oil blend gave the highest scores for off-flavors in the sensory evaluation, demonstrating that several methods, including sensory analysis, should be combined to illustrate the complete picture of lipid oxidation in emulsions....

  5. Plant-Mediated Synthesis of Silver Nanoparticles and Their Stabilization by Wet Stirred Media Milling

    Science.gov (United States)

    Baláž, Matej; Balážová, Ľudmila; Daneu, Nina; Dutková, Erika; Balážová, Miriama; Bujňáková, Zdenka; Shpotyuk, Yaroslav

    2017-02-01

    Within this study, a stable nanosuspension of silver nanoparticles (Ag NPs) was prepared using a two-step synthesis and stabilization approach. The Ag NPs were synthesized from a silver nitrate solution using the Origanum vulgare L. plant extract as the reducing agent. The formation of nanoparticles was finished upon 15 min, and subsequently, stabilization by polyvinylpyrrolidone (PVP) using wet stirred media milling was applied. UV-Vis spectra have shown a maximum at 445 nm, corresponding to the formation of spherical Ag NPs. Infrared spectroscopy was used to examine the interaction between Ag NPs and the capping agents. TEM study has shown the formation of Ag NPs with two different average sizes (38 ± 10 nm and 7 ± 3 nm) after the plant-mediated synthesis, both randomly distributed within the organic matrix. During milling in PVP, the clusters of Ag NPs were destroyed, the Ag NPs were fractionized and embedded in PVP. The nanosuspensions of PVP-capped Ag NPs were stable for more than 26 weeks, whereas for the non-stabilized nanosuspensions, only short-term stability for about 1 week was documented.

  6. Complex effects of ecosystem engineer loss on benthic ecosystem response to detrital macroalgae

    NARCIS (Netherlands)

    Rossi, F.; Gribsholt, B.; Gazeau, F.; Di Santo, V.; Middelburg, J.J.

    2013-01-01

    Ecosystem engineers change abiotic conditions, community assembly and ecosystem functioning. Consequently, their loss may modify thresholds of ecosystem response to disturbance and undermine ecosystem stability. This study investigates how loss of the bioturbating lugworm Arenicola marina modifies t

  7. Complex Effects of Ecosystem Engineer Loss on Benthic Ecosystem Response to Detrital Macroalgae

    NARCIS (Netherlands)

    Rossi, F.; Gribsholt, B.; Gazeau, F.; Di Santo, V.; Middelburg, J.J.

    2013-01-01

    Ecosystem engineers change abiotic conditions, community assembly and ecosystem functioning. Consequently, their loss may modify thresholds of ecosystem response to disturbance and undermine ecosystem stability. This study investigates how loss of the bioturbating lugworm Arenicola marina modifies t

  8. Mercury in forest ecosystems near chlor-alkali plant in the Czech republic

    Science.gov (United States)

    Šimeček, Martin; Navratil, Tomas; Rohovec, Jan

    2016-04-01

    A mercury electrolysis chlor-alkali plant has been operating in Neratovice, the central Czech Republic since year 1948. We focused on the assessment of mercury contamination in the plant surroundings. To assess the contamination extent we sampled organic and mineral soils, bedrock, bark, needles and tree rings from several forest sites with variable distance from plant. The soils were predominately arenic cambisol and the vegetation cover composed of mixed to coniferous forests (majorly Pinus sylvestris). At all the sites, the highest concentrations occurred in the organic rich O horizons of the forest soils. The Hg concentrations increased from Oi horizon (up to 252 μg/kg) with fresh organic matter, through Oe horizons (up to 617 μg/kg) to the Oa horizons (up to 813 μg/kg) with relatively highly decomposed organic matter. The Hg concentrations in mineral soil were significantly lower in range from 3 to 44 μg/kg. Sandstone bedrock contained low Hg concentrations from 2.7 to 4.7 μg/kg. The difference between the high Hg in organic and low Hg in mineral horizons results from order of magnitude different content of soil organic matter. In the same time low Hg in mineral soil indicates low level of Hg migration down the soil profile. Apart from the simple comparison of Hg concentrations, insight into the patterns of soil Hg distribution can be gained by examining the stoichiometric ratios of Hg to C. Soil Hg/C should be greater in areas with greater atmospheric Hg deposition. O horizons of sites closer to plant up to 4.5 km exhibited elevated Hg/C ratios (2.0 - 2.2 μg/g) with respect to those at more distant sites (0.7 - 0.9 μg/g). Values of mineral soil Hg/C ratios varied irrespective to the distance from the plant. Organic soil Hg pool decreased from 13.6 mg/m2 in distance of 1.9 km from the plant to 2.6 mg/m2 in distance of 9 km. But the mineral soil Hg pool ranging from 7.6 to 12.3 mg/m2 exhibited no trend with distance. The polluted sites up to 2.5 km from

  9. Balanced nitrogen economy as a flexible strategy on yield stabilizing and quality of aquatic food crops in wetland ecosystem

    Institute of Scientific and Technical Information of China (English)

    A. M. Puste; P. K. Sarkar; D. K. Das

    2005-01-01

    In wetland ecosystem, nitrogen along with other elements and its management is most imperative for the production of so many aquatic food, non-food and beneficial medicinal plants and for the improvement of soil and water characteristics. With great significant importance of INM (integrated nutrient management) as sources, emphasizing on management on nitrogen as a key element and its divergence, a case study was undertaken on such aquatic food crops (starch and protein-rich, most popular and remunerative) in the farmers' field of low-lying randomized block design, where, three important aquatic food crops (water chestnut (Trapa bispinosa Roxb.), makhana (Eurya/e ferox Salisb.) and water lily (Nymphaea spp.) as major factor and eleven combinations of organic and inorganic sources of nutrients as sub-factor was considered in the experiment. It revealed from the results that the production of fresh kernels or nuts of water chestnut (8.57 t ha-1), matured nut yield of makhana (3.06 t ha-1) and flower stalks of water-lily as vegetables (6.38 t ha-1) including its nutritional quality (starch, protein, sugar and minerals) was remarkably influenced with the application of both organic (neem oilcake @ 0.2 t ha-1) and inorganic sources (NPK @ 30:20:20 kg ha-1 along with spraying of NPK @ 0.5% each over crop canopy at 20 days interval after transplanting) than the other INM combinations applied to the crops. Among the crops, highest WCYE (water chestnut yield equivalence) exhibited in makhana due to its high price of popped-form in the country, which is being exported to other countries at now. Sole application of both (organic and inorganic sources) with lower range did not produce any significant outcome from the study and exhibited lower value for all the crops.Besides production of food crops, INM also greatly influenced the soil and water characterization and it was favourably reflected in this study. The physico-chemical characteristics of soil (textural class, p

  10. Biodiversity increases the resistance of ecosystem productivity to climate extremes.

    Science.gov (United States)

    Isbell, Forest; Craven, Dylan; Connolly, John; Loreau, Michel; Schmid, Bernhard; Beierkuhnlein, Carl; Bezemer, T Martijn; Bonin, Catherine; Bruelheide, Helge; de Luca, Enrica; Ebeling, Anne; Griffin, John N; Guo, Qinfeng; Hautier, Yann; Hector, Andy; Jentsch, Anke; Kreyling, Jürgen; Lanta, Vojtěch; Manning, Pete; Meyer, Sebastian T; Mori, Akira S; Naeem, Shahid; Niklaus, Pascal A; Polley, H Wayne; Reich, Peter B; Roscher, Christiane; Seabloom, Eric W; Smith, Melinda D; Thakur, Madhav P; Tilman, David; Tracy, Benjamin F; van der Putten, Wim H; van Ruijven, Jasper; Weigelt, Alexandra; Weisser, Wolfgang W; Wilsey, Brian; Eisenhauer, Nico

    2015-10-22

    It remains unclear whether biodiversity buffers ecosystems against climate extremes, which are becoming increasingly frequent worldwide. Early results suggested that the ecosystem productivity of diverse grassland plant communities was more resistant, changing less during drought, and more resilient, recovering more quickly after drought, than that of depauperate communities. However, subsequent experimental tests produced mixed results. Here we use data from 46 experiments that manipulated grassland plant diversity to test whether biodiversity provides resistance during and resilience after climate events. We show that biodiversity increased ecosystem resistance for a broad range of climate events, including wet or dry, moderate or extreme, and brief or prolonged events. Across all studies and climate events, the productivity of low-diversity communities with one or two species changed by approximately 50% during climate events, whereas that of high-diversity communities with 16-32 species was more resistant, changing by only approximately 25%. By a year after each climate event, ecosystem productivity had often fully recovered, or overshot, normal levels of productivity in both high- and low-diversity communities, leading to no detectable dependence of ecosystem resilience on biodiversity. Our results suggest that biodiversity mainly stabilizes ecosystem productivity, and productivity-dependent ecosystem services, by increasing resistance to climate events. Anthropogenic environmental changes that drive biodiversity loss thus seem likely to decrease ecosystem stability, and restoration of biodiversity to increase it, mainly by changing the resistance of ecosystem productivity to climate events.

  11. Plant species richness and functional traits affect community stability after a flood event.

    Science.gov (United States)

    Fischer, Felícia M; Wright, Alexandra J; Eisenhauer, Nico; Ebeling, Anne; Roscher, Christiane; Wagg, Cameron; Weigelt, Alexandra; Weisser, Wolfgang W; Pillar, Valério D

    2016-05-19

    Climate change is expected to increase the frequency and magnitude of extreme weather events. It is therefore of major importance to identify the community attributes that confer stability in ecological communities during such events. In June 2013, a flood event affected a plant diversity experiment in Central Europe (Jena, Germany). We assessed the effects of plant species richness, functional diversity, flooding intensity and community means of functional traits on different measures of stability (resistance, resilience and raw biomass changes from pre-flood conditions). Surprisingly, plant species richness reduced community resistance in response to the flood. This was mostly because more diverse communities grew more immediately following the flood. Raw biomass increased over the previous year; this resulted in decreased absolute value measures of resistance. There was no clear response pattern for resilience. We found that functional traits drove these changes in raw biomass: communities with a high proportion of late-season, short-statured plants with dense, shallow roots and small leaves grew more following the flood. Late-growing species probably avoided the flood, whereas greater root length density might have allowed species to better access soil resources brought from the flood, thus growing more in the aftermath. We conclude that resource inputs following mild floods may favour the importance of traits related to resource acquisition and be less associated with flooding tolerance.

  12. THE ASSESMENT OF THE EFFICENCY AND STABILITY OF WORK SEWAGE TREATMENT PLANT IN ZABAJKA

    Directory of Open Access Journals (Sweden)

    Dariusz Młyński

    2016-05-01

    Full Text Available In the article the assessment of the efficiency and stability of work sewage treatment plant in Zabajka was performed based on the results of the physico-chemical measurements raw sewage and treated sewage noted in the period between 2010 and 2014. The analysis was performed for the following pollutants indicators: BOD5, CODCr and total suspended solids. For each of them descriptive statistics, percentage reduction the pollutants indicators and treatment plant reliability factors (WN were calculated. The assessment of the stability of work of sewage treatment plant was performed by using control cards X for the simple test. Based on the obtained results, it was concluded that sewage treatment plant in Zabajka works properly, what is confirmed by high values of the pollutants indicators reduction and the values of WN, which are less than 1.00. The analysis of the control cards indicates instability of the treatment process only for CODCr, but it does not impact on treatment efficiency in relation to this indicator.

  13. The R* rule and energy flux in a plant-nutrient ecosystem.

    Science.gov (United States)

    Ju, Shu; DeAngelis, Donald L

    2009-02-07

    The R* rule predicts that the species that can survive in steady state at the lowest level of limiting resource, R*, excludes all other species. Simple models indicate that this concept is not necessarily consistent with Lotka's conjecture that an ecological system should evolve towards a state of maximum power, Max(G), where G is the power, or rate of biomass production of the system. To explore the relationship in detail, we used a published model of a plant-nutrient system in which a plant can use various strategies, S, of allocation of energy between foliage, roots, and wood. We found that the allocation strategy, S(MinR*), that leads to Min(N(pore*), where N(pore*) is a limiting nutrient in soil pore water in our model (and equivalent to R* in Tilman's notation), is the same as the strategy, S(MaxG_root), for which energy flux to roots is maximized. However, that allocation strategy is different from the strategy, S(MaxG), that produces maximum power, or maximum photosynthetic rate, for the plant system, Max(G). Hence, we conclude that Min(N(pore*) and Max(G) should not necessarily co-occur in an ecological system. We also examined which strategy, S(fit), was fittest; that is, eliminated any other strategies, when allowed to compete. The strategy S(fit) differed from S(MinR*, S(MaxG), and S(MaxG_root), which we demonstrated mathematically. We also considered the feasible situation in which a plant is able to positively influence external nutrient input to the system. Under such conditions, the strategy, S(MaxG_root), that maximizes energy flux to roots was the same as the strategy, S(MaxR*, that leads to maximum concentration of available nutrient in soil pore water, Max(N pore*), and not same as S(MinR*, for Min(N pore*).

  14. Assessing health in agriculture--towards a common research framework for soils, plants, animals, humans and ecosystems.

    Science.gov (United States)

    Vieweger, Anja; Döring, Thomas F

    2015-02-01

    In agriculture and food systems, health-related research includes a vast diversity of topics. Nutritional, toxicological, pharmacological, epidemiological, behavioural, sociological, economic and political methods are used to study health in the five domains of soils, plants, livestock, humans and ecosystems. An idea developed in the early founding days of organic agriculture stated that the health of all domains is one and indivisible. Here we show that recent research reveals the existence and complex nature of such health links among domains. However, studies of health aspects in agriculture are often separated by disciplinary boundaries. This restrains the understanding of health in agricultural systems. Therefore we explore the opportunities and limitations of bringing perspectives together from the different domains. We review current approaches to define and assess health in agricultural contexts, comparing the state of the art of commonly used approaches and bringing together the presently disconnected debates in soil science, plant science, veterinary science and human medicine. Based on a qualitative literature analysis, we suggest that many health criteria fall into two paradigms: (1) the Growth Paradigm, where terms are primarily oriented towards continued growth; (2) the Boundary Paradigm, where terms focus on maintaining or coming back to a status quo, recognising system boundaries. Scientific health assessments in agricultural and food systems need to be explicit in terms of their position on the continuum between Growth Paradigm and Boundary Paradigm. Finally, we identify areas and concepts for a future direction of health assessment and research in agricultural and food systems.

  15. Anthropogenic impacts on the stability of the forest ecosystems in Belgrade - comparative analysis of Košutnjak forest and Zvezdarska forest

    Directory of Open Access Journals (Sweden)

    Rašković Dragana

    2015-01-01

    Full Text Available In this paper will be analyzed the environmental statusof the two recently protected forest areas in Belgrade -Košutnjak forest and Zvezdarska forest. Due to their specific position inside the urban structure, these park forests are exposed to the high level of pollution and degradation originating from anthropogenic sources. This paper will include all present forms of threats to the stability of these ecosystems, both in their immediate surroundings, as well as within their borders. For clear presentation of the devastating anthropogenic impact,on the protected forest ecosystems remote sensing - NDVI analysis of the appropriate satelite imagesegments will be preformed in order to detect the differences of the state of vegetation covers registrated in 1986 and 2010. According tothe need for efficient management system for the affected natural areas in the urban structure, in the end will be presented concrete protection measures, whose continous aplication can bring to the progradation of their state.

  16. Integration and inheritance stability of foreign Bt toxin gene in the bivalent insectresistant transgenic cotton plants

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    Genetic and expressional stability of Bt toxin gene is crucial for the breeding of insect-resistant transgenic cotton varieties and their commercialization. Genomic Southern blot analysis of R3, R4 and R5 generations of bivalent transgenic insect-resistant cotton plants was done in order to determine the integration, the copy number and the inheritance stability of Bt toxin gene in the transgenic cotton plants. The results indicated that there was a 4.7 kb positive band in the Southern blot when the genomic DNA of the bivalent transgenic insect-resistant cotton plants and the positive control (the plasmid) were digested with HindⅢ respectively. This result proved that the Bt toxin gene had been integrated into the genome of the cotton in full length.There is only one Xho I restriction site in the Bt toxin gene.Southern blot analysis indicated that many copies of Bt toxin gene had been integrated into the genome of the cotton when the genomic DNA of transgenic plants was digested with Xho I. Among them, there were four copies (about 17.7, 8,5.5 and 4.7 kb in size) existing in all the tested plants of R3,R4 and R5 generations. The preliminary conclusion was that there were more than four copies of Bt toxin gene integrated into the genome of the cotton, among them, more than one copy can express and inherit steadily. This result provides a scientific basis for the breeding of the bivalent insect-resistant transgenic cotton plants and its commercialization.``

  17. Differences in plant cover and species composition of semiarid grassland communities of Central Mexico and its effects on net ecosystem exchange

    Directory of Open Access Journals (Sweden)

    J. Delgado-Balbuena

    2012-12-01

    Full Text Available Changes in land use across the semiarid grasslands of Northern Mexico have driven a decline of plant cover and alteration of plant species composition. A number of different plant communities have resulted from these changes, however, their implications on the carbon cycle and regional carbon balance are still poorly understood. Here, we examined the effects of plant cover loss and changes in species composition on net ecosystem CO2 exchange (NEE and their biotic and abiotic controls. Five typical plant community types were examined in the semiarid grassland by encasing the entire above-ground ecosystem using the geodesic dome method. Sites included an oat crop (crop, a moderately grazed grassland (moderate grazing, a 28 yr-old grazing exclosure (exclosure, an overgrazed site with low perennial grass cover (overgrazed, and an overgrazed site presenting shrub encroachment (shrub encroachment. For natural vegetation, rates of daytime NEE for sites with a high plant cover (exclosure and moderate grazing were similar (P>0.05 as compared to sites with low plant cover (overgrazed and shrub encroachment. However, night time NEE (carbon loss was more than double (P<0.05 for sites with high plant cover compared to sites with low cover, resulting into slight C sinks for the low plant cover sites and neutral or sources for the high plant cover sites on an annual basis. Differences in plant cover and its associated biomass defined the sensitivity to environmental controls. Thus, daytime NEE in low plant cover sites reached light compensation points at lower PPFD values than those from high plant cover sites. Differences in species composition did not influence NEE rates even though there were transient or permanent changes in C3 vs. C4 functional groups.

  18. Plant uptake, translocation, and return of polycyclic aromatic hydrocarbons via fine root branch orders in a subtropical forest ecosystem.

    Science.gov (United States)

    Chen, Zheng-Xia; Ni, Hong-Gang; Jing, Xin; Chang, Wen-Jing; Sun, Jian-Lin; Zeng, Hui

    2015-07-01

    Fine roots of woody plants are a heterogeneous system differing markedly in structure and function. Nevertheless, knowledge about the plant uptake of organic pollutants via fine roots is scarce to date. In the present study, plant uptake, translocation, and return of polycyclic aromatic hydrocarbons (PAHs) via fine roots in a subtropical forest ecosystem were investigated. Levels of Σ15PAHs in different fine root branch orders of Michelia macclurei, Cryptocarya concinna, Cryptocarya chinensis, and Canthium dicoccums varied from 5072±1419 ng g(-1) to 6080±1656 ng g(-1), 4037±410 ng g(-1) to 6101±972 ng g(-1), 3308±1191 ng g(-1) to 4283±237 ng g(-1), and 3737±800 ng g(-1) to 4895±1216 ng g(-1), respectively. Overall, concentrations of low-molecular-weight PAHs with 2-3 aromatic rings were higher than high-molecular-weight PAHs with 4-6 aromatic rings in all fine root branch orders. There were obvious translocations of PAHs between adjacent branch orders and a net accumulation of PAHs may occur in the fourth- and fifth-order roots. The storage of PAHs in the fine root system showed an obvious increasing trend along the branch orders ascending for all tree species. The return flux of PAHs via fine roots mortality showed an obvious decreasing trend with the branch orders ascending across the four tree species. Lower order roots contributed greatly to the total PAHs return flux. Our results indicated that fine roots turnover is an effective pathway for perennial tree species to remove environmental toxicants absorbed into them.

  19. Phenology and cover of plant growth forms predict herbivore habitat selection in a high latitude ecosystem.

    Science.gov (United States)

    Iversen, Marianne; Fauchald, Per; Langeland, Knut; Ims, Rolf A; Yoccoz, Nigel G; Bråthen, Kari Anne

    2014-01-01

    The spatial and temporal distribution of forage quality is among the most central factors affecting herbivore habitat selection. Yet, for high latitude areas, forage quantity has been found to be more important than quality. Studies on large ungulate foraging patterns are faced with methodological challenges in both assessing animal movements at the scale of forage distribution, and in assessing forage quality with relevant metrics. Here we use first-passage time analyses to assess how reindeer movements relate to forage quality and quantity measured as the phenology and cover of growth forms along reindeer tracks. The study was conducted in a high latitude ecosystem dominated by low-palatable growth forms. We found that the scale of reindeer movement was season dependent, with more extensive area use as the summer season advanced. Small-scale movement in the early season was related to selection for younger stages of phenology and for higher abundances of generally phenologically advanced palatable growth forms (grasses and deciduous shrubs). Also there was a clear selection for later phenological stages of the most dominant, yet generally phenologically slow and low-palatable growth form (evergreen shrubs). As the summer season advanced only quantity was important, with selection for higher quantities of one palatable growth form and avoidance of a low palatable growth form. We conclude that both forage quality and quantity are significant predictors to habitat selection by a large herbivore at high latitude. The early season selectivity reflected that among dominating low palatability growth forms there were palatable phenological stages and palatable growth forms available, causing herbivores to be selective in their habitat use. The diminishing selectivity and the increasing scale of movement as the season developed suggest a response by reindeer to homogenized forage availability of low quality.

  20. Interactions between plant traits and sediment characteristics influencing species establishment and scale-dependent feedbacks in salt marsh ecosystems

    NARCIS (Netherlands)

    Schwarz, C.; Bouma, T.J.; Zhang, L.Q.; Temmerman, S.; Ysebaert, T.; Herman, P.M.J.

    2015-01-01

    The importance of ecosystem engineering and biogeomorphic processes in shaping many aquatic and semi-aquatic landscapes is increasingly acknowledged. Ecosystem engineering and biogeomorphic landscape formation involves two critical processes: (1) species establishment, and (2) scale-dependent

  1. Interactions between plant traits and sediment characteristics influencing species establishment and scale-dependent feedbacks in salt marsh ecosystems

    NARCIS (Netherlands)

    Schwarz, C.; Bouma, T.J.; Zhang, L.Q.; Temmerman, S.; Ysebaert, T.; Herman, P.M.J.

    2015-01-01

    The importance of ecosystem engineering and biogeomorphic processes in shaping many aquatic and semi-aquatic landscapes is increasingly acknowledged. Ecosystem engineering and biogeomorphic landscape formation involves two critical processes: (1) species establishment, and (2) scale-dependent

  2. Enhancing Legume Ecosystem Services through an Understanding of Plant-Pollinator Interplay.

    Science.gov (United States)

    Suso, María J; Bebeli, Penelope J; Christmann, Stefanie; Mateus, Célia; Negri, Valeria; Pinheiro de Carvalho, Miguel A A; Torricelli, Renzo; Veloso, Maria M

    2016-01-01

    Legumes are bee-pollinated, but to a different extent. The importance of the plant-pollinator interplay (PPI), in flowering crops such as legumes lies in a combination of the importance of pollination for the production service and breeding strategies, plus the increasing urgency in mitigating the decline of pollinators through the development and implementation of conservation measures. To realize the full potential of the PPI, a multidisciplinary approach is required. This article assembles an international team of genebank managers, geneticists, plant breeders, experts on environmental governance and agro-ecology, and comprises several sections. The contributions in these sections outline both the state of the art of knowledge in the field and the novel aspects under development, and encompass a range of reviews, opinions and perspectives. The first three sections explore the role of PPI in legume breeding strategies. PPI based approaches to crop improvement can make it possible to adapt and re-design breeding strategies to meet both goals of: (1) optimal productivity, based on an efficient use of pollinators, and (2) biodiversity conservation. The next section deals with entomological aspects and focuses on the protection of the "pest control service" and pollinators in legume crops. The final section addresses general approaches to encourage the synergy between food production and pollination services at farmer field level. Two basic approaches are proposed: (a) Farming with Alternative Pollinators and (b) Crop Design System.

  3. Plant functional traits of dominant native and invasive species in mediterranean-climate ecosystems.

    Science.gov (United States)

    Funk, Jennifer L; Standish, Rachel J; Stock, William D; Valladares, Fernando

    2016-01-01

    The idea that dominant invasive plant species outperform neighboring native species through higher rates of carbon assimilation and growth is supported by several analyses of global data sets. However, theory suggests that native and invasive species occurring in low-resource environments will be functionally similar, as environmental factors restrict the range of observed physiological and morphological trait values. We measured resource-use traits in native and invasive plant species across eight diverse vegetation communities distributed throughout the five mediterranean-climate regions, which are drought prone and increasingly threatened by human activities, including the introduction of exotic species. Traits differed strongly across the five regions. In regions with functional differences between native and invasive species groups, invasive species displayed traits consistent with high resource acquisition; however, these patterns were largely attributable to differences in life form. We found that species invading mediterranean-climate regions were more likely to be annual than perennial: three of the five regions were dominated by native woody species and invasive annuals. These results suggest that trait differences between native and invasive species are context dependent and will vary across vegetation communities. Native and invasive species within annual and perennial groups had similar patterns of carbon assimilation and resource use, which contradicts the widespread idea that invasive species optimize resource acquisition rather than resource conservation. .

  4. Enhancing legume ecosystem services through an understanding of plant-pollinator interplay

    Directory of Open Access Journals (Sweden)

    Maria Jose eSuso

    2016-03-01

    Full Text Available Legumes are bee-pollinated, but to a different extent. The importance of the plant-pollinator interplay (PPI, in flowering crops such as legumes lies in a combination of the importance of pollination for the production service and breeding strategies, plus the increasing urgency in mitigating the decline of pollinators through the development and implementation of conservation measures. To realize the full potential of the PPI, a multidisciplinary approach is required. This article assembles an international team of genebank managers, geneticists, plant breeders, experts on environmental governance and agro-ecology, and comprises several sections. The contributions in these sections outline both the state of the art of knowledge in the field and the novel aspects under development, and encompass a range of reviews, opinions and perspectives. The first three sections explore the role of PPI in legume breeding strategies. PPI based approaches to crop improvement can make it possible to adapt and re-design breeding strategies to meet both goals of: 1 optimal productivity, based on an efficient use of pollinators, and 2 biodiversity conservation. The next section deals with entomological aspects and focuses on the protection of the pest control service and pollinators in legume crops. The final section addresses general approaches to encourage the synergy between food production and pollination services at farmer field level. Two basic approaches are proposed: a Farming with Alternative Pollinators (FAP and b Crop Design System (CDS.

  5. Plant species diversity of wetland ecosystem in an arid and semi-arid region in northwest China

    Institute of Scientific and Technical Information of China (English)

    LI Rui; LIU Yunfang; ZHANG Kebin

    2007-01-01

    In order to study the changes of plant species diversity along the biotope gradient and its influencing factors in a wetland-add grassland ecosystem in the add and semi-arid regions of northwest China,four transect lines were set along the biotope gradient in four directions:east,northeast,west and northwest,and altogether 123 sample plots were investigated on species composition,density,foliage cover,height and biomass (calculated in fresh weight).The whole study area was divided into the Wetland zone,the ecotone and the arid grassland zone in terms of habitat characteristics and vegetation types.In this paper,we analyzed and compared the species diversity in the ecotone of a wetland-dry grassland ecosystem in Yanchi County,Ningxia Hui Autonomous Region,with the help of biodiversity software BioDiversity Pro and statistical software Microcal Origin,as well as the combined measurement of species diversity indices.The results revealed distinct differences between those three vegetation zones along each transect line.The ecotone had the highest richness indices (R) and comprehensive diversity indices (Y),reflecting the edge effect.The greatest evenness indices (E) were found in the add grassland zones.This result agreed with the phenomenon of desertification reversion,vegetation restoration and dominant communities' formation.As for the four transect lines,the east and the northeast scored higher in each diversity index than the others due to less human disturbance,gentler topography uplift and more intercepted materials and energies.The highest Simpson index value was found in the northeast transect line,which was 39.9% higher than the lowest in the Northwest.

  6. Phosphorus status of soils from contrasting forested ecosystems in Southwestern Siberia: combined effects of plant species and climate

    Science.gov (United States)

    Achat, D. L.; Bakker, M. R.; Augusto, L.; Derrien, D.; Gallegos, N.; Lashchinskiy, N.; Milin, S.; Nikitich, P.; Raudina, T.; Rusalimova, O.; Zeller, B.; Barsukov, P.

    2012-06-01

    The Russian boreal forest, which mainly consists of extensive forests in Siberia, is the largest continuous forest region on Earth and represents 70 % of the world's boreal forest. Siberian forest is a tremendous repository of terrestrial organic carbon (C), which may increase owing to climate change, potential increases in ecosystem productivity and hence C sequestration. Phosphorus (P) availability could limit the C sequestration potential, but tree roots may mine the soil deeper to increase access to mineral P. Improved understanding and quantification of the processes controlling P availability in surface and deep soil layers of forest ecosystems are thus required. Relative contributions of organic and inorganic P and, consequently, P availability in forest ecosystems depend on decomposition processes, which could be strongly affected by vegetation composition, temperature, precipitation, and their changes due to a warming climate. The objectives of the present study were to (1) evaluate P status of surface and deep forest soil horizons from two contrasted biomes in Southwestern Siberia (i.e. forest steppe in the West Siberian plain and blackish ("chernevaya" in Russian) taiga in the low Salair mountains) and (2) assess the effects of vegetation (siberian fir stand, common aspen stand and herbs in a forest gap) and local climate on soil P fractions. Results revealed high contents in total P (645-1042 mg kg-1 in the surface mineral soils) and available inorganic P (diffusive phosphate ions in one week = 83-126 mg kg-1). In addition, there was an accumulation of diffusive phosphate ions in the subsoils resulting from differences between soil horizons in total inorganic P and soil properties. Consequently, deeper root systems may mine substantial amounts of available P for the trees and the potential enhanced growth and C sequestration due to climate change should thus a~priori not be P-limited. High proportions of total organic P (47-56 % of total P in the

  7. Phosphorus status of soils from contrasting forested ecosystems in Southwestern Siberia: combined effects of plant species and climate

    Directory of Open Access Journals (Sweden)

    D. L. Achat

    2012-06-01

    Full Text Available The Russian boreal forest, which mainly consists of extensive forests in Siberia, is the largest continuous forest region on Earth and represents 70 % of the world's boreal forest. Siberian forest is a tremendous repository of terrestrial organic carbon (C, which may increase owing to climate change, potential increases in ecosystem productivity and hence C sequestration. Phosphorus (P availability could limit the C sequestration potential, but tree roots may mine the soil deeper to increase access to mineral P. Improved understanding and quantification of the processes controlling P availability in surface and deep soil layers of forest ecosystems are thus required. Relative contributions of organic and inorganic P and, consequently, P availability in forest ecosystems depend on decomposition processes, which could be strongly affected by vegetation composition, temperature, precipitation, and their changes due to a warming climate. The objectives of the present study were to (1 evaluate P status of surface and deep forest soil horizons from two contrasted biomes in Southwestern Siberia (i.e. forest steppe in the West Siberian plain and blackish ("chernevaya" in Russian taiga in the low Salair mountains and (2 assess the effects of vegetation (siberian fir stand, common aspen stand and herbs in a forest gap and local climate on soil P fractions. Results revealed high contents in total P (645–1042 mg kg−1 in the surface mineral soils and available inorganic P (diffusive phosphate ions in one week = 83–126 mg kg−1. In addition, there was an accumulation of diffusive phosphate ions in the subsoils resulting from differences between soil horizons in total inorganic P and soil properties. Consequently, deeper root systems may mine substantial amounts of available P for the trees and the potential enhanced growth and C sequestration due to climate change should thus a~priori not be P-limited. High proportions of total

  8. Rising sea level, temperature, and precipitation impact plant and ecosystem responses to elevated CO2 on a Chesapeake Bay wetland: review of a 28-year study.

    Science.gov (United States)

    Drake, Bert G

    2014-11-01

    An ongoing field study of the effects of elevated atmospheric CO2 on a brackish wetland on Chesapeake Bay, started in 1987, is unique as the longest continually running investigation of the effects of elevated CO2 on an ecosystem. Since the beginning of the study, atmospheric CO2 increased 18%, sea level rose 20 cm, and growing season temperature varied with approximately the same range as predicted for global warming in the 21st century. This review looks back at this study for clues about how the effects of rising sea level, temperature, and precipitation interact with high atmospheric CO2 to alter the physiology of C3 and C4 photosynthetic species, carbon assimilation, evapotranspiration, plant and ecosystem nitrogen, and distribution of plant communities in this brackish wetland. Rising sea level caused a shift to higher elevations in the Scirpus olneyi C3 populations on the wetland, displacing the Spartina patens C4 populations. Elevated CO2 stimulated carbon assimilation in the Scirpus C3 species measured by increased shoot and root density and biomass, net ecosystem production, dissolved organic and inorganic carbon, and methane production. But elevated CO2 also decreased biomass of the grass, S. patens C4. The elevated CO2 treatment reduced tissue nitrogen concentration in shoots, roots, and total canopy nitrogen, which was associated with reduced ecosystem respiration. Net ecosystem production was mediated by precipitation through soil salinity: high salinity reduced the CO2 effect on net ecosystem production, which was zero in years of severe drought. The elevated CO2 stimulation of shoot density in the Scirpus C3 species was sustained throughout the 28 years of the study. Results from this study suggest that rising CO2 can add substantial amounts of carbon to ecosystems through stimulation of carbon assimilation, increased root exudates to supply nitrogen fixation, reduced dark respiration, and improved water and nitrogen use efficiency.

  9. Carbon Cycling in Restored Wisconsin Grasslands: Examining Linkages Between Plant Diversity, Microbial Communities and Ecosystem Processes

    Science.gov (United States)

    Cahill, K. N.; Kucharik, C. J.; Balser, T. C.; Foley, J. A.

    2002-12-01

    It is important to characterize the variability of carbon (C) fluxes and stocks and the relationship between biotic and abiotic factors and C sequestration, a proposed strategy to help mitigate climate change. An observation site to study C cycling was established on land enrolled in the USDA Conservation Reserve Program in southwestern Wisconsin in spring 2002 on silt-loam soil. The site was converted from intensive row-crop agriculture in 1987 to three adjacent land cover types: an assortment of native C4 grasses, two C3 grasses and a nitrogen-fixer, and a disk planted, no-tillage food plot rotation of maize and soybeans. Key goals of the study were to characterize the effect of plant species composition and microbial community characteristics on carbon cycling in an attempt to link above- and below-ground processes. Measurements of soil surface CO2 efflux were made on a near-weekly basis during the growing season using a LICOR-6400, concurrently with soil surface moisture adjacent to the CO2 collars. Thermocouples were installed to record hourly average air temperature and soil temperature at 5 depths, from 2 to 70 cm, and water content sensors made hourly average measurements at 15 and 30 cm. Leaf area index measurements were made weekly, aboveground vegetation biomass was collected monthly, and belowground root biomass was collected bimonthly. Monthly microbial measurements included an assessment of community physiological profiles using BiOLOG, and assays of community composition (lipid analysis) and activity. Preliminary results suggest that land cover types significantly altered carbon cycling and microbial community structure and function, leading to different rates of C sequestration.

  10. Ecological adaptation strategies of annual plants in artificial vegetation-stabilized sand dune in Shapotou Region

    Institute of Scientific and Technical Information of China (English)

    ZHANG Jingguang; LI Xinrong; WANG Xinping; WANG Gang

    2004-01-01

    Taking annual plant Eragrostis poaeides in the artificial vegetation-stabilized sand dune in the Shapotou Experimental Research Station as example, study has been done on the adaptation strategies of annual plants to random environment through fixed quadrat observations of population changes and fixed plant determinations of individual growth, seed germination,population dynamics, spatial distribution pattern of population, competition and regulation. During the growing season, the survival rate of annual plants depends on the precipitation intensity and precipitation duration which activate the germination of seeds. The optimal germination strategy of annual plants in this habitat during the growing season appears as continuous germination under suitable conditions. Such continuous germination is an adaptive characteristic of annual plants to random environment. In addition, the variation processes of population size and regulation mechanism of E. poaeoides are studied. Statistical results of natural population in four consecutive years show that water condition in the habitat is the leading factor affecting the population dynamics of E. poaeoides. During the establishment period E. poaeoides had a higher death rate, but in the middle to later period they could survive stably. Due to the limitation of soil moisture, the competition among individuals for water inevitably led to self-thinning phenomena. Under very arid condition, the survival curve of annual herbs entirely appears as Deevey Ⅲ type (C type), but under relatively adequate precipitation condition, the survival curve appears as intermediate type. The strategy of life history obviously appears as r-strategy. Plant species of r-strategy often occurs in the early succession stage of the communities. In the relatively adequate and evenly-distributed rainfall years, E. poaeoides population exhibited a density-dependent, i. e., survival rate increased with decrease in population density. The main pattern to

  11. Science and Measurement Requirements for a Plant Physiology and Functional Types Mission: Measuring the Composition, Function and Health of Global Land and Coastal Ocean Ecosystems

    Science.gov (United States)

    Green, Robert O.; Rogez, Francois; Green, Rob; Ungar, Steve; Knox, Robert; Asner, Greg; Muller-Karger, Frank; Bissett, Paul; Chekalyuk, Alex; Dierssen, Heidi; Gamon, John; Hook, Simon; Meister, Gerhard; Middleton, Betsy; Ollinger, Scott; Roberts, Dar; Siegel, Dave; Townsend, Phil; Saatchi, Sassan; Unstin, Susan; Turner, Woody; Wickland, Diane; Bontempi, Paula; Emanuel, Bill

    2007-01-01

    This slide presentation reviews the proposed Plant Physiology and Functional Types (PPFT) Mission. The National Academy of Sciences Decadal Survey, placed a critical priority on a Mission to observe distribution and changes in ecosystem functions. The PPFT satellite mission provides the essential measurements needed to assess drivers of change in biodiversity and ecosystem services that affect human welfare. The presentation reviews the science questions that the mission will be designed to answer, the science rationale, the science measurements, the mission concept, the planned instrumentation, the calibration method, and key signal to noise ratios and uniformity requirements.

  12. Stabilization and dewatering of wastewater treatment plants sludge using the Fenton process

    Directory of Open Access Journals (Sweden)

    Abolfazl Azhdarpoor

    2015-11-01

    Full Text Available Wastewater sludge typically contains large amounts of water and organic materials; therefore, its stabilization and dewatering is of particular importance. In this study, Fenton oxidation process is used for stabilization and dewatering of sludge in the output of a wastewater treatment plant. To evaluate the sludge stabilization and dewatering, specific resistance to filtration (SRF, volatile organic compounds (VSS, total suspended solids (TSS, soluble chemical oxygen demand (SCOD and heterotrophic bacteria were measured. During the experiment, the optimal values of various parameters such as pH (2-9, hydrogen peroxide (0.015- 0.18mol/L, Fe2+ (0.008- 0.1mol/L and time (5 - 60 minutes for optimum sludge dewatering and stabilization were investigated. The results showed that the highest percentages of SRF reduction and removal rates of SCOD, VSS and TSS were 99.48, 61, 42, and 41 percent respectively. These results were obtained in optimum pH 5, 0.05 mol/l Fe2+, 0.12 mol/l hydrogen peroxide, and the retention time of 15 minutes. The removal rate of heterotrophic bacteria increased with increasing dose of hydrogen peroxide, so that a removal rate of 84 percent was observed at a dose of 0.18 mol/l. In general, Fenton process can reduce volatile organic materials and chemical oxygen demand of the sludge resulting in its significant stabilization and dewatering. In general, Fenton process can reduce volatile organic materials and chemical oxygen demand of the sludge resulting in its significant stabilization and dewatering.

  13. Is an ecosystem services-based approach developed for setting specific protection goals for plant protection products applicable to other chemicals?

    Science.gov (United States)

    Maltby, Lorraine; Jackson, Mathew; Whale, Graham; Brown, A Ross; Hamer, Mick; Solga, Andreas; Kabouw, Patrick; Woods, Richard; Marshall, Stuart

    2017-02-15

    Clearly defined protection goals specifying what to protect, where and when, are required for designing scientifically sound risk assessments and effective risk management of chemicals. Environmental protection goals specified in EU legislation are defined in general terms, resulting in uncertainty in how to achieve them. In 2010, the European Food Safety Authority (EFSA) published a framework to identify more specific protection goals based on ecosystem services potentially affected by plant protection products. But how applicable is this framework to chemicals with different emission scenarios and receptor ecosystems? Four case studies used to address this question were: (i) oil refinery waste water exposure in estuarine environments; (ii) oil dispersant exposure in aquatic environments; (iii) down the drain chemicals exposure in a wide range of ecosystems (terrestrial and aquatic); (iv) persistent organic pollutant exposure in remote (pristine) Arctic environments. A four-step process was followed to identify ecosystems and services potentially impacted by chemical emissions and to define specific protection goals. Case studies demonstrated that, in principle, the ecosystem services concept and the EFSA framework can be applied to derive specific protection goals for a broad range of chemical exposure scenarios. By identifying key habitats and ecosystem services of concern, the approach offers the potential for greater spatial and temporal resolution, together with increased environmental relevance, in chemical risk assessments. With modifications including improved clarity on terminology/definitions and further development/refinement of the key concepts, we believe the principles of the EFSA framework could provide a methodical approach to the identification and prioritization of ecosystems, ecosystem services and the service providing units that are most at risk from chemical exposure.

  14. Impact assessment of the Fukushima Nuclear Power Plant accidental emission on the Barents Sea ecosystem

    Science.gov (United States)

    Matishov, Gennady; Ilyin, Gennady; Kasatkina, Nadezhda; Usiagina, Irina; Pavelskaya, Elena

    2013-04-01

    littoral of bays, the specific activity of 137Cs did not exceed the trace quantity as well (less than 0.5 Bq/kg of raw mass). The latest radioecological studies of the Barents Sea commercial fish showed that all investigated species (such as Atlantic cod, long rough dab, spotted wolffish) contain less than 0.2 Bq/kg of 137Cs. Thus spectrum of artificial radioisotopes and their radioactivity level in both abiotic and biotic components of the Barents Sea ecosystem have not changed after the Fukushima accident. Compared to the data of recent years, these characteristics are stable; within the background limits owing to the global circulation of radionuclides. This work was supported by the international project CEEPRA (project no. 01/2010/007/KO130) implemented within the frame of Kolarctic program.

  15. Residues of plant protection products in grey partridge eggs in French cereal ecosystems.

    Science.gov (United States)

    Bro, Elisabeth; Devillers, James; Millot, Florian; Decors, Anouk

    2016-05-01

    The contamination of the eggs of farmland birds by currently used plant protection products (PPPs) is poorly documented despite a potential to adversely impact their breeding performance. In this context, 139 eggs of 52 grey partridge Perdix perdix clutches, collected on 12 intensively cultivated farmlands in France in 2010-2011, were analysed. Given the great diversity of PPPs applied on agricultural fields, we used exploratory GC/MS-MS and LC/MS-MS screenings measuring ca. 500 compounds. The limit of quantification was 0.01 mg/kg, a statutory reference. A total of 15 different compounds were detected in 24 clutches. Nine of them have been used by farmers to protect crops against fungi (difenoconazole, tebuconazole, cyproconazole, fenpropidin and prochloraz), insects (lambda-cyhalothrin and thiamethoxam/clothianidin) and weeds (bromoxynil and diflufenican). Some old PPPs were also detected (fipronil(+sulfone), HCH(α,β,δ isomers), diphenylamine, heptachlor(+epoxyde), DDT(Σisomers)), as well as PCBs(153, 180). Concentrations ranged between literature.

  16. Trait space of rare plants in a fire-dependent ecosystem.

    Science.gov (United States)

    Ames, Gregory M; Wall, Wade A; Hohmann, Matthew G; Wright, Justin P

    2017-08-01

    The causes of species rarity are of critical concern because of the high extinction risk associated with rarity. Studies examining individual rare species have limited generality, whereas trait-based approaches offer a means to identify functional causes of rarity that can be applied to communities with disparate species pools. Differences in functional traits between rare and common species may be indicative of the functional causes of species rarity and may therefore be useful in crafting species conservation strategies. However, there is a conspicuous lack of studies comparing the functional traits of rare species and co-occurring common species. We measured 18 important functional traits for 19 rare and 134 common understory plant species from North Carolina's Sandhills region and compared their trait distributions to determine whether there are significant functional differences that may explain species rarity. Flowering, fire, and tissue-chemistry traits differed significantly between rare and common, co-occurring species. Differences in specific traits suggest that fire suppression has driven rarity in this system and that changes to the timing and severity of prescribed fire may improve conservation success. Our method provides a useful tool to prioritize conservation efforts in other systems based on the likelihood that rare species are functionally capable of persisting. © 2016 The Authors. Conservation Biology published by Wiley Periodicals, Inc. on behalf of Society for Conservation Biology.

  17. Directional, stabilizing, and disruptive trait selection as alternative mechanisms for plant community assembly.

    Science.gov (United States)

    Rolhauser, Andrés G; Pucheta, Eduardo

    2017-03-01

    How plant functional traits (e.g., seed mass) drive species abundance within communities remains an unsolved question. Borrowing concepts from natural selection theory, we propose that trait-abundance relationships can generally correspond to one of three modes of trait selection: directional (a rectilinear relationship, where species at one end of a trait axis are most abundant), stabilizing (an n-shaped relationship), and disruptive (a u-shaped relationship). Stabilizing selection (i.e., the functional convergence of abundant species) would result from positive density-dependent interactions (e.g., facilitation) or due to generalized trade-offs in resource acquisition/use, while disruptive selection (i.e., the divergence of abundant species) would result from negative density-dependent interactions (e.g., competition) or due to environmental heterogeneity. These selection modes can be interpreted as proxies for community-level trait-fitness functions, which establish the degree to which traits are truly "functional". We searched for selection modes in a desert annual-plant community in Argentina (which was divided into winter and summer guilds) to test the hypothesis that the relative importance of disruptive mechanisms (competition, disturbances) decreases with the increase of abiotic stress, a stabilizing agent. Average density was analyzed as a function of eight traits generally linked to resource acquisition and competitive ability (maximum plant height, leaf size, specific leaf area, specific root length), resource retention and stress tolerance (leaf dissection, leaf dry matter content, specific root volume), and regeneration (seed mass) using multiple quadratic-regression models. Trait selection was stabilizing and/or directional when the environment was harshest (winter) and disruptive and/or directional when conditions were milder (summer). Selection patterns differed between guilds for two important traits: plant height and seed mass. These results

  18. Influence of the Asian Monsoon on net ecosystem carbon exchange in two major plant functional types in Korea

    Directory of Open Access Journals (Sweden)

    H. Kwon

    2009-11-01

    Full Text Available Considering the feedback loops in radiation, temperature, and soil moisture with alterations in rainfall patterns, the influence of the changing monsoon on net ecosystem CO2 exchange can be critical to the estimation of carbon balance in Asia. In this paper, we examined the eddy covariance CO2 fluxes observed from 2004 to 2008 in two major plant functional types in KoFlux, i.e., the Gwangneung deciduous forest (GDK site and the Haenam farmland (HFK site. The objectives of the study were to (1 quantify the net ecosystem CO2 exchange (NEE, ecosystem respiration (RE, and gross primary production (GPP, (2 examine their interannual patterns, and (3 assess the mechanism for the coupling of carbon and water exchange associated with the summer monsoon. The GDK site, which had a maximum leaf area index (LAI of ~5, was on average a relatively weak carbon sink with NEE of −84 gC m−2 y−1, RE of 1028 gC m−2 y−1, and GPP of 1113 gC m−2 y−1. Despite about 20% larger GPP (of 1321 gC m−2 y−1 in comparison with the GDK site, the HFK site (with the maximum LAI of 3 to 4 was a weaker carbon sink with NEE of −58 gC m−2 y−1 because of greater RE of 1263 gC m−2 y−1. In both sites, the annual patterns of NEE and GPP had a striking "mid-season depression" each year with two distinctive peaks of different timing and magnitude, whereas RE did not. The mid-season depression at the GDK site occurred typically from early June to late August, coinciding with the season of summer monsoon when the solar radiation decreased substantially due to frequent rainfalls and cloudiness. At the HFK site, the mid-season depression began earlier in May and continued until the end of July due to land use management (e.g., crop rotation in addition to such disturbances as summer monsoon and typhoons

  19. [Insect community structure and its stability in a Zanthoxylum bungeanum garden with different planting pattern].

    Science.gov (United States)

    Zhang, Xiao-Ming; Li, Qiang; Chen, Guo-Hua; Yang, Jie; Gao, Xin; Song, Jia-Xiong

    2009-08-01

    An investigation was made on the insect community composition and structure in a Zanthoxylum bungeanum garden with corn-soybean - Z. bungeanum intercropping, soybean - Z. bungeanum intercropping, corn - Z. bungeanum intercropping, and only Z. bungeanum planting in Zhaotong City of Yunnan Province, and the community character index and principal component analysis were used to study the characters and stability of the insect community. A total of 326 insect species were recorded. In intercropped plots, the abundance, diversity, and evenness index of insect community were higher while the dominance index was lower, compared with those in monocultured Z. bungeanum plot. The diversity index of insect community decreased in the order of corn-soybean- Z. bungeanum intercropping > soybean - Z. bungeanum intercropping > corn - Z. bungeanum intercropping > only Z. bungeanum planting, and the insect community in corn-soybean - Z. bungeanum intercropping plot was relatively stable.

  20. Spatial pattern of a plant community in a wetland ecosystem in a semi-arid region in northwestern China

    Institute of Scientific and Technical Information of China (English)

    Kebin ZHANG; Rui LI; Yunfang LIU; Baitian WANG; Xiaohui YANG; Ruiping HOU

    2008-01-01

    The spatial distribution characteristics of plant communities in a wetland-dry grassland ecosystem in arid and semi-arid regions in northwestern China and the main factors affecting the distribution pattern were studied. The Siertan wetland in the Haba Lake Nature Reserve was the study area. Four transect lines, each about 1 km long, were set up in the growing season along the biotope gradient in four directions: east, northeast, west and northwest. Attributes measured include frequency of occurrence, height, density, coverage, biomass and envir-onmental soil factors. The data were analyzed using a two-way indicative species analysis (TWINSPAN), detrended correspondence analysis (DCA) and Spear-man correlation coefficients. On this basis, the vegetation in the Siertan wetland was classified into three types and 14 associations. The first vegetation type was halophytic marsh vegetation, mainly distributed in the wetland zone. This type largely contains halophyte and hygric plants and its representative association is Phragmites communis + Kalidiumfoliatum. The second type was meadow vegeta-tion, distributed in the ecotone. The meadow vegetation species are mainly mesophytic and their representative association is Nitraria tangutorum+ Pennisetum flacci-dum. The third vegetation type is grassland vegetation, which mainly consists of mesophytic and xerophytes, dis-tributed in the arid grassland zone. The representative association of the third vegetation type is the association of Anaeurolepidium secalium + Saussurea runcinata. Correlation analysis between the axes of DCA and envir-onmental soil factors shows that soil moisture content, organic matter, soil salt content and total nitrogen are the main environmental factors affecting the pattern of vegetation distribution along the biotope gradients from wetland to arid grassland. Other factors affecting the vegetation are microtopography and grazing pressure. Additionally, we have reported modifications and

  1. Prosopis laevigata and Mimosa biuncifera (Leguminosae, jointly influence plant diversity and soil fertility of a Mexican semiarid ecosystem

    Directory of Open Access Journals (Sweden)

    Rosalva García-Sánchez

    2012-03-01

    Full Text Available Prosopis laevigata and Mimosa biuncifera are frequently found in arid and semiarid shrublands, but scarce information is available about their influence on plant community structure and soil fertility. We compared plant community structure, diversity and soil nutrients of three semiarid shrubland sites located in Mezquital Valley, Mexico. These sites differ in their dominant species: Site 1 (Bingu P. laevigata, Site 2 (González M. biuncifera, and Site 3 (Rincón with the presence of both legumes. The results showed that the plant community with P. laevigata and M. biuncifera (Site 3 had more cover, taller plants and higher plant diversity than sites with only one legume (Site 1 and Site 2. Soil organic matter (SOM, soil organic carbon (SOC, total nitrogen (TN, phosphorus-Olsen (P and C mineralization were higher in the soil under the canopy of both legumes than in bare soil. In contrast, soil cation concentrations were lower under the canopy of P. laevigata, but not for M. biuncifera. In addition, the density of arbuscular mycorrhizal fungi spores was higher within the soil under the canopy of M. biuncifera than in the soil under the canopy of P. laevigata. Thus, resource islands (RI created by P. laevigata increased the amounts of SOC, TN and P when compared with the RI of M. biuncifera. This study provided evidences about the importance of species identity in order to expand the niche availability for the establishment of other plants, and highlights that P. laevigata and M. biuncifera jointly influencing plant colonization within semiarid ecosystemsProsopis laevigata y Mimosa biuncifera coexisten en los matorrales semiáridos; sin embargo, se desconoce su influencia sobre la diversidad de la comunidad vegetal y el suelo. Este estudio evaluó el efecto de P. laevigata y M. biuncifera sobre la estructura, diversidad vegetal y nutrimentos del suelo, en tres matorrales del Valle del Mezquital, México. Los sitios difieren en la especie dominante

  2. Structure of soybean seed coat peroxidase: a plant peroxidase with unusual stability and haem-apoprotein interactions

    DEFF Research Database (Denmark)

    Henriksen, A; Mirza, O; Indiani, C

    2001-01-01

    Soybean seed coat peroxidase (SBP) is a peroxidase with extraordinary stability and catalytic properties. It belongs to the family of class III plant peroxidases that can oxidize a wide variety of organic and inorganic substrates using hydrogen peroxide. Because the plant enzyme is a heterogeneous...

  3. 150 years of macronutrient change in unfertilized plant-soil ecosystems: Observations vs simulations

    Science.gov (United States)

    Davies, Jessica; Tipping, Ed; Whitmore, Andy

    2017-04-01

    Understanding changes in plant-soil carbon and nutrients using data alone is difficult due to the linkages between carbon, nitrogen and phosphorus cycles (C, N and P), and multiple changing long-term drivers (e.g. climate, land-use, and atmospheric N deposition). Hence, dynamic models are a vital tool for disentangling these drivers, helping us understand the dominant processes and drivers and predict future change. However, it is essential that models are tested against data if their outputs are to be concluded upon with confidence. Here, a simulation of C, N and P cycles using the N14CP model was compared with time-series observations of C, N and P in soils and biomass from the Rothamsted Research long-term experiments spanning 150 years, providing an unprecedented temporal integrated test of such a model. N14CP reproduced broad trends in soil organic matter (SOM) C, N and P, vegetation biomass and N and P leaching. Subsequently, the model was used to decouple the effects of land management and elevated nitrogen deposition in these experiments. Elevated N deposition over the last 150 years is shown to have increased net primary productivity (NPP) 4.5-fold and total carbon sequestration 5-fold at the Geescroft Wilderness experiment, which was re-wilded to woodland in 1886. In contrast, the model predicts that for cropped grassland conditions at the Park Grass site, elevated N deposition has very little effect on SOM, as increases in NPP are diverted from the soil. More broadly, these results suggest that N deposition is likely to have had a large effect on SOM and NPP in northern temperate and boreal semi-natural grasslands and forests. However, in cropped and grazed systems in the same region, whilst NPP may have been supported in part by elevated N deposition, declines in SOM may not have been appreciably counteracted by increased N availability.

  4. Carbon dynamics in aboveground biomass of co-dominant plant species in a temperate grassland ecosystem: same or different?

    Science.gov (United States)

    Ostler, Ulrike; Schleip, Inga; Lattanzi, Fernando A; Schnyder, Hans

    2016-04-01

    Understanding the role of individual organisms in whole-ecosystem carbon (C) fluxes is probably the biggest current challenge in C cycle research. Thus, it is unknown whether different plant community members share the same or different residence times in metabolic (τmetab ) and nonmetabolic (i.e. structural) (τnonmetab ) C pools of aboveground biomass and the fraction of fixed C allocated to aboveground nonmetabolic biomass (Anonmetab ). We assessed τmetab , τnonmetab and Anonmetab of co-dominant species from different functional groups (two bunchgrasses, a stoloniferous legume and a rosette dicot) in a temperate grassland community. Continuous, 14-16-d-long (13) C-labeling experiments were performed in September 2006, May 2007 and September 2007. A two-pool compartmental system, with a well-mixed metabolic and a nonmixed nonmetabolic pool, was the simplest biologically meaningful model that fitted the (13) C tracer kinetics in the whole-shoot biomass of all species. In all experimental periods, the species had similar τmetab (5-8 d), whereas τnonmetab ranged from 20 to 58 d (except for one outlier) and Anonmetab from 7 to 45%. Variations in τnonmetab and Anonmetab were not systematically associated with species or experimental periods, but exhibited relationships with leaf life span, particularly in the grasses. Similar pool kinetics of species suggested similar kinetics at the community level.

  5. ANALYSIS OF STABILITY OF TRINUCLEOTIDE TTC MOTIFS IN COMMON FLAX PLANTED IN THE CHERNOBYL AREA

    Directory of Open Access Journals (Sweden)

    Veronika Lancíková

    2015-02-01

    Full Text Available Flax (Linum usitatissimum L. is one of the oldest domesticated plants — it was cultivated as early as in ancient Egypt and Samaria 10,000 years ago to serve as a source of fiber and oil, whence it later spread around the world. Compared with other plants, the flax genome consists of a high number of repetitive sequences, middle repetitive sequences and small repetitive sequences of nucleotides. The aim of the study was to analyze the stability of the existing trinucleotides motifs of microsatellite DNA of the flax genome (genotype Kyivskyi, growing in the Chernobyl conditions. The Chernobyl area is the most extensive “natural” laboratory suitable for the study of radiation effects. Over the last 20 years, the researches collected important knowledge about the effects of low and high radiation doses on the DNA isolated from the plant material growing on the remediated fields near Chernobyl and the plant material from fields contaminated by radioactive cesium 137Cs and strontium 90Sr. Using eight pairs of microsatellite primers, we successfully amplified the samples from the remediated fields. For each primer in the control samples and remediated samples, we detected 1 to 3 fragments per locus, each in size up to 120 to 250 base pairs. The applied microsatellite primers confirmed the monomorphic condition of microsatellite loci.

  6. The variable effects of soil nitrogen availability and insect herbivory on aboveground and belowground plant biomass in an old-field ecosystem.

    Science.gov (United States)

    Blue, Jarrod D; Souza, Lara; Classen, Aimée T; Schweitzer, Jennifer A; Sanders, Nathan J

    2011-11-01

    Nutrient availability and herbivory can regulate primary production in ecosystems, but little is known about how, or whether, they may interact with one another. Here, we investigate how nitrogen availability and insect herbivory interact to alter aboveground and belowground plant community biomass in an old-field ecosystem. In 2004, we established 36 experimental plots in which we manipulated soil nitrogen (N) availability and insect abundance in a completely randomized plot design. In 2009, after 6 years of treatments, we measured aboveground biomass and assessed root production at peak growth. Overall, we found a significant effect of reduced soil N availability on aboveground biomass and belowground plant biomass production. Specifically, responses of aboveground and belowground community biomass to nutrients were driven by reductions in soil N, but not additions, indicating that soil N may not be limiting primary production in this ecosystem. Insects reduced the aboveground biomass of subdominant plant species and decreased coarse root production. We found no statistical interactions between N availability and insect herbivory for any response variable. Overall, the results of 6 years of nutrient manipulations and insect removals suggest strong bottom-up influences on total plant community productivity but more subtle effects of insect herbivores on aspects of aboveground and belowground production.

  7. Reclamation after oil and gas development does not speed up succession or plant community recovery in big sagebrush ecosystems in Wyoming

    Science.gov (United States)

    Rottler, Caitlin M.; Burke, Ingrid C.; Palmquist, Kyle A.; Bradford, John B.; Lauenroth, William K.

    2017-01-01

    Article for intended outlet: Restoration Ecology. Abstract: Reclamation is an application of treatment(s) following a disturbance to promote succession and accelerate the return of target conditions. Previous studies have framed reclamation in the context of succession by studying its effectiveness in re-establishing late-successional plant communities. Re-establishment of these plant communities is especially important and potentially challenging in regions such as drylands and shrub steppe ecosystems where succession proceeds slowly. Dryland shrub steppe ecosystems are frequently associated with areas rich in fossil-fuel energy sources, and as such the need for effective reclamation after disturbance from fossil-fuel-related energy development is great. Past research in this field has focused primarily on coal mines; few researchers have studied reclamation after oil and gas development. To address this research gap and to better understand the effect of reclamation on rates of succession in dryland shrub steppe ecosystems, we sampled oil and gas wellpads and adjacent undisturbed big sagebrush plant communities in Wyoming, USA and quantified the extent of recovery for major functional groups on reclaimed and unreclaimed (recovered via natural succession) wellpads relative to the undisturbed plant community. Reclamation increased the rate of recovery for all forb and grass species as a group and for perennial grasses, but did not affect other functional groups. Rather, analyses comparing recovery to environmental variables and time since wellpad abandonment showed that recovery of other groups were affected primarily by soil texture and time since wellpad abandonment. This is consistent with studies in other ecosystems where reclamation has been implemented, suggesting that reclamation may not help re-establish late-successional plant communities more quickly than they would re-establish naturally.

  8. Prediction of plant vulnerability to salinity increase in a coastal ecosystem by stable isotopic composition (δ18O) of plant stem water: a model study

    Science.gov (United States)

    Zhai, Lu; Jiang, Jiang; DeAngelis, Don; Sternberg, Leonel d.S.L

    2016-01-01

    Sea level rise and the subsequent intrusion of saline seawater can result in an increase in soil salinity, and potentially cause coastal salinity-intolerant vegetation (for example, hardwood hammocks or pines) to be replaced by salinity-tolerant vegetation (for example, mangroves or salt marshes). Although the vegetation shifts can be easily monitored by satellite imagery, it is hard to predict a particular area or even a particular tree that is vulnerable to such a shift. To find an appropriate indicator for the potential vegetation shift, we incorporated stable isotope 18O abundance as a tracer in various hydrologic components (for example, vadose zone, water table) in a previously published model describing ecosystem shifts between hammock and mangrove communities in southern Florida. Our simulations showed that (1) there was a linear relationship between salinity and the δ18O value in the water table, whereas this relationship was curvilinear in the vadose zone; (2) hammock trees with higher probability of being replaced by mangroves had higher δ18O values of plant stem water, and this difference could be detected 2 years before the trees reached a tipping point, beyond which future replacement became certain; and (3) individuals that were eventually replaced by mangroves from the hammock tree population with a 50% replacement probability had higher stem water δ18O values 3 years before their replacement became certain compared to those from the same population which were not replaced. Overall, these simulation results suggest that it is promising to track the yearly δ18O values of plant stem water in hammock forests to predict impending salinity stress and mortality.

  9. δ 13C of ecosystem-respired CO2 along a gradient of C3 woody-plant encroachment into C4 grassland

    Science.gov (United States)

    Sun, W.; Scott, R. L.; Resco, V.; Cable, J. M.; Huxman, T. E.; Williams, D. G.

    2006-12-01

    Woody plant encroachment into grassland has the potential to affect net primary production, in part by changing the sensitivities of photosynthesis and respiration to precipitation. Encroachment of mesquite (Prosopis) into floodplain sacaton (Sporobolus) grassland along the San Pedro River in southeastern Arizona has altered the magnitude and seasonal pattern of net ecosystem carbon exchange and ecosystem respiration. We hypothesized that because mesquite accesses ground water in these floodplain environments, its advancement and dominance in former grassland reduces the sensitivities of photosynthesis and autotrophic respiration to inputs of growing season precipitation. The observed elevated rates of ecosystem respiration following rainfall inputs are likely to result from microbial decomposition of labile organic matter derived from the highly productive mesquite trees. We used the Keeling plot method to monitor carbon-13 composition of nocturnal ecosystem-respired CO2 (δ 13CR) during the growing seasons of 2005 and 2006 at three sites spanning a gradient of mesquite invasion: C4 sacaton grassland, mixed mesquite/grass shrubland and C3 mesquite woodland. δ 13CR in the C4 grassland increased from -18.8‰ during the dry premonsoon period to -16.7‰ after the onset of summer rains, whereas δ 13CR in the mixed shrub/grass and woodland ecosystems declined from -20.9‰ to - 24‰ and from -20.8‰ to -24.7‰, respectively, following the onset of summer rains. The δ 13CR of respired CO2 was collected separately from soil, roots, leaves and surface litter to evaluate the contribution of each of these components to ecosystem respiration. Partitioning of ecosystem respiration using these isotope end-members and responses to short-term (days) changes in shallow (0-5cm) soil moisture content suggest that in former grassland now occupied by mesquite woodland, rainfall inputs primarily stimulate microbial decomposition and have little effect on autotrophic respiration

  10. Utilization of power plant bottom-ash particles as stabilizer in aluminum foams

    Energy Technology Data Exchange (ETDEWEB)

    Asavavisithchai, Seksak; Prapajaraswong, Attanadol [Chulalongkorn Univ., Bangkok (Thailand). Dept. of Metallurgical Engineering

    2013-07-01

    Aluminum foams, produced via powder metallurgical (PM) process, normally require the addition of ceramic particles in compaction stage, in order to increase both foamability of precursors and mechanical properties of the final foam products. Bottom ash particles are a by-product waste obtained from thermoelectric power plants which are commonly found to be used in landfill facilities. The major chemical constituent, approximately between 30 wt.-% and 60 wt.-%, of bottom ash particles is SiO{sub 2}, depending on chemical composition in coal, sintering condition and environment, and other process parameters. In this study, we explore the feasibility of utilizing bottom ash particles of thermoelectric power plant wastes as stabilizer in aluminum foams. A small amount of two-size bottom ash particles (mean size of 78 {mu}m and 186 {mu}m), between 1 wt.-% and 5 wt.-%, have been added to aluminum foams. Foam expansion, macro- and microstructures as well as mechanical properties, such as compressive strength and microhardness, were investigated. The results from the present study suggest that bottom ash particles can be used as a stabilizing material which can improve both cellular structure and mechanical properties of aluminum foams. (orig.)

  11. A whole plant approach to evaluate the water use of mediterranean maquis species in a coastal dune ecosystem

    Directory of Open Access Journals (Sweden)

    S. Mereu

    2009-02-01

    Full Text Available An integrated approach has been used to analyse the water relations of three Mediterranean species, A. unedo L., Q. ilex L. and P. latifolia L. co-occurring in a coastal dune ecosystem. The approach considered leaf level gas exchange, sap flow measurements and structural adaptations between 15 May and 31 July 2007, and was necessary to capture the different response of the three species to the same environment. The complexity of the response was proportional to the complexity of the system, characterized by a sandy soil with a low water retention capacity and the presence of a water table. The latter did not completely prevent the development of a drought response, and species differences in this responses have been partially attributed to a different root distribution. Sap flow of A. unedo decreased rapidly in response to the decline of Soil Water Content, while that of Q. ilex decreased only moderately. Midday leaf water potential of P. latifolia and A. unedo was between 2.2 and 2.7 MPa through the measuring period, while in Q. ilex it reached a value of 3.4 MPa at the end of the season. A. unedo was the only species to decrease the leaf area to sapwood area ratio from 23.9±1.2 (May to 15.2±1.5 (July, as a response to drought. A. unedo also underwent an almost stepwise loss on hydraulic conductivity, such a loss didn't occur for Q. ilex, while P. latifolia was able to slightly increase hydraulic conductivity, showing how different plant compartments coordinate differently between species as a response to drought. Such different coordination affects the gas exchange between vegetation and the atmosphere, and has implications for the response of the Mediterranean coastal dune ecosystems to climate change.

  12. Plant litter chemistry alters the content and composition of organic carbon associated with soil mineral and aggregate fractions in invaded ecosystems.

    Science.gov (United States)

    Tamura, Mioko; Suseela, Vidya; Simpson, Myrna; Powell, Brian; Tharayil, Nishanth

    2017-10-01

    Through the input of disproportionate quantities of chemically distinct litter, invasive plants may potentially influence the fate of organic matter associated with soil mineral and aggregate fractions in some of the ecosystems they invade. Although context dependent, these native ecosystems subjected to prolonged invasion by exotic plants may be instrumental in distinguishing the role of plant-microbe-mineral interactions from the broader edaphic and climatic influences on the formation of soil organic matter (SOM). We hypothesized that the soils subjected to prolonged invasion by an exotic plant that input recalcitrant litter (Japanese knotweed, Polygonum cuspidatum) would have a greater proportion of plant-derived carbon (C) in the aggregate fractions, as compared with that in adjacent soil inhabited by native vegetation that input labile litter, whereas the soils under an invader that input labile litter (kudzu, Pueraria lobata) would have a greater proportion of microbial-derived C in the silt-clay fraction, as compared with that in adjacent soils that receive recalcitrant litter. At the knotweed site, the higher C content in soils under P. cuspidatum, compared with noninvaded soils inhabited by grasses and forbs, was limited to the macroaggregate fraction, which was abundant in plant biomarkers. The noninvaded soils at this site had a higher abundance of lignins in mineral and microaggregate fractions and suberin in the macroaggregate fraction, partly because of the greater root density of the native species, which might have had an overriding influence on the chemistry of the above-ground litter input. At the kudzu site, soils under P. lobata had lower C content across all size fractions at a 0-5 cm soil depth despite receiving similar amounts of Pinus litter. Contrary to our prediction, the noninvaded soils receiving recalcitrant Pinus litter had a similar abundance of plant biomarkers across both mineral and aggregate fractions, potentially because of

  13. Stabilization/solidification of battery debris & lead impacted material at Schuylkill Metals, Plant City, Florida

    Energy Technology Data Exchange (ETDEWEB)

    Anguiano, T.; Floyd, D. [ENTACT, Inc., Irving, TX (United States)

    1997-12-31

    The Schuylkill Metals facility in Plant City Florida (SMPCI) operated as a battery recycling facility for approximately 13 years. During its operation, the facility disposed of battery components in surrounding wetland areas. In March of 1991 the U.S. EPA and SMPCI entered into a Consent Decree for the remediation of the SMPCI site using stabilization/solidification and on-site disposal. In November of 1994, ENTACT began remediation at the facility and to date has successfully stabilized/solidified over 228,000 tons of lead impacted battery components and lead impacted material. The ENTACT process reduces the size of the material to be treated to ensure that complete mixing of the phosphate/cement additive is achieved thereby promoting the chemical reactions of stabilization and solidification. ENTACT has met the following performance criteria for treated material at the SMPCI site: (1) Hydraulic Conductivity less than 1x10{sup -6} cm/s, (2) Unconfined Compressive Strength greater than 50 psi, (3) Lead, Cadmium, Arsenic, Chromium TCLP Leachability below hazardous levels.

  14. Potential effects of desalinated water quality on the operation stability of wastewater treatment plants.

    Science.gov (United States)

    Lew, Beni; Cochva, Malka; Lahav, Ori

    2009-03-15

    Desalinated water is expected to become the major source of drinking water in many places in the near future, and thus the major source of wastewater to arrive at wastewater treatment plants. The paper examines the effect of the alkalinity value with which the water is released from the desalination plant on the alkalinity value that would develop within the wastewater treatment process under various nitrification-denitrification operational scenarios. The main hypothesis was that the difference in the alkalinity value between tap water and domestic wastewater is almost exclusively a result of the hydrolysis of urea (NH(2)CONH(2), excreted in the human urine) to ammonia (NH(3)), regardless of the question what fraction of NH(3(aq)) is transformed to NH(4)(+). Results from a field study show that the ratio between the alkalinity added to tap water when raw wastewater is formed (in meq/l units) and the TAN (total ammonia nitrogen, mole/l) concentration in the raw wastewater is almost 1:1 in purely domestic sewage and close to 1:1 in domestic wastewater streams mixed with light industry wastewaters. Having established the relationship between TAN and total alkalinity in raw wastewater the paper examines three theoretical nitrification-denitrification treatment scenarios in the wastewater treatment plant (WWTP). The conclusion is that if low-alkalinity desalinated water constitutes the major water source arriving at the WWTP, external alkalinity will have to be added in order to avoid pH drop and maintain process stability. The results lead to the conclusion that supplying desalinated water with a high alkalinity value (e.g. > or =100 mg/l as CaCO(3)) would likely prevent the need to add costly basic chemicals in the WWTP, while, in addition, it would improve the chemical and biological stability of the drinking water in the distribution system.

  15. Relationships between plant diversity and the abundance and α-diversity of predatory ground beetles (Coleoptera: Carabidae) in a mature Asian temperate forest ecosystem.

    Science.gov (United States)

    Zou, Yi; Sang, Weiguo; Bai, Fan; Axmacher, Jan Christoph

    2013-01-01

    A positive relationship between plant diversity and both abundance and diversity of predatory arthropods is postulated by the Enemies Hypothesis, a central ecological top-down control hypothesis. It has been supported by experimental studies and investigations of agricultural and grassland ecosystems, while evidence from more complex mature forest ecosystems is limited. Our study was conducted on Changbai Mountain in one of the last remaining large pristine temperate forest environments in China. We used predatory ground beetles (Coleoptera: Carabidae) as target taxon to establish the relationship between phytodiversity and their activity abundance and diversity. Results showed that elevation was the only variable included in both models predicting carabid activity abundance and α-diversity. Shrub diversity was negatively and herb diversity positively correlated with beetle abundance, while shrub diversity was positively correlated with beetle α-diversity. Within the different forest types, a negative relationship between plant diversity and carabid activity abundance was observed, which stands in direct contrast to the Enemies Hypothesis. Furthermore, plant species density did not predict carabid α-diversity. In addition, the density of herbs, which is commonly believed to influence carabid movement, had little impact on the beetle activity abundance recorded on Changbai Mountain. Our study indicates that in a relatively large and heterogeneous mature forest area, relationships between plant and carabid diversity are driven by variations in environmental factors linked with altitudinal change. In addition, traditional top-down control theories that are suitable in explaining diversity patterns in ecosystems of low diversity appear to play a much less pronounced role in highly complex forest ecosystems.

  16. Relationships between plant diversity and the abundance and α-diversity of predatory ground beetles (Coleoptera: Carabidae in a mature Asian temperate forest ecosystem.

    Directory of Open Access Journals (Sweden)

    Yi Zou

    Full Text Available A positive relationship between plant diversity and both abundance and diversity of predatory arthropods is postulated by the Enemies Hypothesis, a central ecological top-down control hypothesis. It has been supported by experimental studies and investigations of agricultural and grassland ecosystems, while evidence from more complex mature forest ecosystems is limited. Our study was conducted on Changbai Mountain in one of the last remaining large pristine temperate forest environments in China. We used predatory ground beetles (Coleoptera: Carabidae as target taxon to establish the relationship between phytodiversity and their activity abundance and diversity. Results showed that elevation was the only variable included in both models predicting carabid activity abundance and α-diversity. Shrub diversity was negatively and herb diversity positively correlated with beetle abundance, while shrub diversity was positively correlated with beetle α-diversity. Within the different forest types, a negative relationship between plant diversity and carabid activity abundance was observed, which stands in direct contrast to the Enemies Hypothesis. Furthermore, plant species density did not predict carabid α-diversity. In addition, the density of herbs, which is commonly believed to influence carabid movement, had little impact on the beetle activity abundance recorded on Changbai Mountain. Our study indicates that in a relatively large and heterogeneous mature forest area, relationships between plant and carabid diversity are driven by variations in environmental factors linked with altitudinal change. In addition, traditional top-down control theories that are suitable in explaining diversity patterns in ecosystems of low diversity appear to play a much less pronounced role in highly complex forest ecosystems.

  17. Eighty-five million years of Pacific Ocean gyre ecosystem structure: long-term stability marked by punctuated change.

    Science.gov (United States)

    Sibert, Elizabeth; Norris, Richard; Cuevas, Jose; Graves, Lana

    2016-05-25

    While the history of taxonomic diversification in open ocean lineages of ray-finned fish and elasmobranchs is increasingly known, the evolution of their roles within the open ocean ecosystem remains poorly understood. To assess the relative importance of these groups through time, we measured the accumulation rate of microfossil fish teeth and elasmobranch dermal denticles (ichthyoliths) in deep-sea sediment cores from the North and South Pacific gyres over the past 85 million years (Myr). We find three distinct and stable open ocean ecosystem structures, each defined by the relative and absolute abundance of elasmobranch and ray-finned fish remains. The Cretaceous Ocean (pre-66 Ma) was characterized by abundant elasmobranch denticles, but low abundances of fish teeth. The Palaeogene Ocean (66-20 Ma), initiated by the Cretaceous/Palaeogene mass extinction, had nearly four times the abundance of fish teeth compared with elasmobranch denticles. This Palaeogene Ocean structure remained stable during the Eocene greenhouse (50 Ma) and the Eocene-Oligocene glaciation (34 Ma), despite large changes in the overall accumulation of both groups during those intervals, suggesting that climate change is not a primary driver of ecosystem structure. Dermal denticles virtually disappeared from open ocean ichthyolith assemblages approximately 20 Ma, while fish tooth accumulation increased dramatically in variability, marking the beginning of the Modern Ocean. Together, these results suggest that open ocean fish community structure is stable on long timescales, independent of total production and climate change. The timing of the abrupt transitions between these states suggests that the transitions may be due to interactions with other, non-preserved pelagic consumer groups.

  18. Differential response of carbon fluxes to climate in three peatland ecosystems that vary in the presence and stability of permafrost

    Science.gov (United States)

    Euskirchen, Eugenie S; Edgar, C.W.; Turetsky, M.R.; Waldrop, Mark P.; Harden, Jennifer W.

    2016-01-01

    Changes in vegetation and soil properties following permafrost degradation and thermokarst development in peatlands may cause changes in net carbon storage. To better understand these dynamics, we established three sites in Alaska that vary in permafrost regime, including a black spruce peat plateau forest with stable permafrost, an internal collapse scar bog formed as a result of thermokarst, and a rich fen without permafrost. Measurements include year-round eddy covariance estimates of carbon dioxide (CO2), water, and energy fluxes, associated environmental variables, and methane (CH4) fluxes at the collapse scar bog. The ecosystems all acted as net sinks of CO2 in 2011 and 2012, when air temperature and precipitation remained near long-term means. In 2013, under a late snowmelt and late leaf out followed by a hot, dry summer, the permafrost forest and collapse scar bog were sources of CO2. In this same year, CO2 uptake in the fen increased, largely because summer inundation from groundwater inputs suppressed ecosystem respiration. CO2 exchange in the permafrost forest and collapse scar bog was sensitive to warm air temperatures, with 0.5 g C m−2 lost each day when maximum air temperature was very warm (≥29°C). The bog lost 4981 ± 300 mg CH4 m−2 between April and September 2013, indicating that this ecosystem acted as a significant source of both CO2 and CH4 to the atmosphere in 2013. These results suggest that boreal peatland responses to warming and drying, both of which are expected to occur in a changing climate, will depend on permafrost regime.

  19. Idaho Chemical Processing Plant low-level waste grout stabilization development program FY-96 status report

    Energy Technology Data Exchange (ETDEWEB)

    Herbst, A.K.

    1996-09-01

    The general purpose of the Grout Stabilization Development Program is to solidify and stabilize the liquid low-level wastes (LLW) generated at the Idaho Chemical Processing Plant (ICPP). It is anticipated that LLW will be produced from the following: (1) chemical separation of the tank farm high-activity sodium-bearing waste; (2) retrieval, dissolution, and chemical separation of the aluminum, zirconium, and sodium calcines; (3) facility decontamination processes; and (4) process equipment waste. The main tasks completed this fiscal year as part of the program were chromium stabilization study for sodium-bearing waste and stabilization and solidification of LLW from aluminum and zirconium calcines. The projected LLW will be highly acidic and contain high amounts of nitrates. Both of these are detrimental to Portland cement chemistry; thus, methods to precondition the LLW and to cure the grout were explored. A thermal calcination process, called denitration, was developed to solidify the waste and destroy the nitrates. A three-way blend of Portland cement, blast furnace slag, and fly ash was successfully tested. Grout cubes were prepared at various waste loadings to maximize loading while meeting compressive strength and leach resistance requirements. For the sodium LLW, a 25% waste loading achieves a volume reduction of 3.5 and a compressive strength of 2,500 pounds per square inch while meeting leach, mix, and flow requirements. It was found that the sulfur in the slag reduces the chromium leach rate below regulatory limits. For the aluminum LLW, a 15% waste loading achieves a volume reduction of 8.5 and a compressive strength of 4,350 pounds per square inch while meeting leach requirements. Likewise for zirconium LLW, a 30% waste loading achieves a volume reduction of 8.3 and a compressive strength of 3,570 pounds per square inch.

  20. Above vs. belowground plant biomass along a barrier island: Implications for dune stabilization.

    Science.gov (United States)

    Charbonneau, Bianca R; Wnek, John P; Langley, J Adam; Lee, Gina; Balsamo, Ronald A

    2016-11-01

    Coastal regions are inherently and increasingly vulnerable and geomorphologically unstable, yet are invaluable economic and residential hubs. Dunes are dynamic buffers to erosion and the most natural, economical, and effective defense for coastal communities. Vegetation is integral to dune structure as it facilitates accretion and stabilization. Differences in the vegetation and root density likely translate to variability in coastal erosion prevention, but this notion has been largely unconsidered. We directly compared stabilizing factors, depth and density, of the root systems of two dominant mid-Atlantic dune plant species, native American beach grass (Ammophila breviligulata) and invasive Asiatic sand sedge (Carex kobomugi). Despite high plant density, C. kobomugi is targeted for removal in restoration efforts as its roots are assumed to provide less effective stabilization than A. breviligulata. We collected 30 cores and hand dug 14 A. breviligulata ramets at Island Beach State Park, New Jersey to examine biomass, root:shoot ratios, and root density. C. kobomugi had a more extensive root system with a root:shoot ratio of 11.36:1 compared to 1.62:1 for A. breviligulata. Similarly, cores 60 cm deep and 7.6 cm wide were sufficient to attain fully intact A. breviligulata roots, which did not extend deeper than 40 cm, but insufficient for C. kobomugi roots which extended beyond the sampling system vertically and horizontally. Scaling these findings to m(-2), aboveground biomass is relatively equal, but C. kobomugi had over 700% more root mass m(-2) than A. breviligulata. These results have strong implications for dune management. The root system of C. kobomugi may be better adapted to stabilize dunes and thus protect coastal areas during small and large-scale perturbations than previously supposed. This is a unique situation whereby the creation of monocultures will hyperstabilize dunes and make them more resistant to erosion at the cost of reduced

  1. No post-Cretaceous ecosystem depression in European forests? Rich insect-feeding damage on diverse middle Palaeocene plants, Menat, France.

    Science.gov (United States)

    Wappler, Torsten; Currano, Ellen D; Wilf, Peter; Rust, Jes; Labandeira, Conrad C

    2009-12-22

    Insect herbivores are considered vulnerable to extinctions of their plant hosts. Previous studies of insect-damaged fossil leaves in the US Western Interior showed major plant and insect herbivore extinction at the Cretaceous-Palaeogene (K-T) boundary. Further, the regional plant-insect system remained depressed or ecologically unbalanced throughout the Palaeocene. Whereas Cretaceous floras had high plant and insect-feeding diversity, all Palaeocene assemblages to date had low richness of plants, insect feeding or both. Here, we use leaf fossils from the middle Palaeocene Menat site, France, which has the oldest well-preserved leaf assemblage from the Palaeocene of Europe, to test the generality of the observed Palaeocene US pattern. Surprisingly, Menat combines high floral diversity with high insect activity, making it the first observation of a 'healthy' Palaeocene plant-insect system. Furthermore, rich and abundant leaf mines across plant species indicate well-developed host specialization. The diversity and complexity of plant-insect interactions at Menat suggest that the net effects of the K-T extinction were less at this greater distance from the Chicxulub, Mexico, impact site. Along with the available data from other regions, our results show that the end-Cretaceous event did not cause a uniform, long-lasting depression of global terrestrial ecosystems. Rather, it gave rise to varying regional patterns of ecological collapse and recovery that appear to have been strongly influenced by distance from the Chicxulub structure.

  2. The effect of water plant extracts addition on the oxidative stability of meat products

    Directory of Open Access Journals (Sweden)

    Karolina M. Wójciak

    2011-06-01

    Full Text Available Background. Natural antioxidants extracted from plants have a lot of antioxidants catechins, epigallocatechins (green tea rosmariquinone, rosmaridiphenol (rosemary, capsaicinoids (red pepper. They can be used as alternatives to the synthetic antioxidants because of their equivalence or greater effect on inhibition of lipid oxidation and haem pigment (nitrosohemachrome protection. The aim of the study was to compare the effect of addition of green tea extract, red pepper extract and rosemary extract while curing process on colour and lipid stability during refrigerated storage of meat products. Material and methods. The pork meat was ground (10 mm plate and divided into four equal parts. To the first part (control sample – C was added curring mixture in amount of 2.2% in a ratio of meat dissolved in water. To the rests of parts were added the same curring mixtures in the same proportion dissolved in 0.5% water plant extracts: green tea (GT, red pepper (P, rosemary (R respectively. All samples were left at 4°C for 24 hours. After curing, samples were stuffed in casings and then heated in water until a final internal temperature of 70°C was reached. All samples were stored up to 30 days at 4°C. Analysis of acidity, oxidation – reduction potential, thiobarbituric acid reactive substances (TBARS, surface colour (Hunter L*, a* and b* values were measured directly after production and after 10, 20 and 30 days of chilling storage. Results. The addition of the plant extracts (pepper, green tea, rosemary to the pork meat samples does not change significantly acidity of the samples during chilling storage. All plants extracts effectively reduce lipid oxidation in cooked pork meat compared to the control. Pepper extract was effective in maintaining redness because of its reduction activity (low potential redox value in sample and low TBARS values in sample during chilling storage. Conclusions. Addition of pepper extract and green tea extract in

  3. Multivariate analysis as a tool for measuring the stability of morphometric traits in Lycopersicon plants from in vitro culture

    Directory of Open Access Journals (Sweden)

    Pratta Guillermo

    2000-01-01

    Full Text Available The phenotypic stability of morphometric traits in Lycopersicon spp. (stem perimeter at the base, middle and top, and number of flowers per cluster was measured by multivariate analysis through a progeny test in order to estimate the genetic stability of these traits. Principal components were calculated for two groups of Lycopersicon spp., non-regenerated plants and the progeny of regenerated plants. Analysis of variance was performed to support principal component analysis. Both groups presented similar eigenvalues and eigenvectors, while no significant differences were found between any of the traits studied. These results indicated that the phenotypic structure was the same among the progeny of regenerated and non-regenerated plants, so that no variation would occur in in vitro culture. Multivariate analysis proved to be an appropriate methodology for the measurement of the stability of morphometric traits after one regeneration cycle.

  4. Mechanistic insights on the responses of plant and ecosystem gas exchange to global environmental change: lessons from Biosphere 2.

    Science.gov (United States)

    Gonzalez-Meler, Miquel A; Rucks, Jessica S; Aubanell, Gerard

    2014-09-01

    Scaling up leaf processes to canopy/ecosystem level fluxes is critical for examining feedbacks between vegetation and climate. Collectively, studies from Biosphere 2 Laboratory have provided important insight of leaf-to-ecosystem investigations of multiple environmental parameters that were not before possible in enclosed or field studies. B2L has been a testing lab for the applicability of new technologies such as spectral approaches to detect spatial and temporal changes in photosynthesis within canopies, or for the development of cavity ring-down isotope applications for ecosystem evapotranspiration. Short and long term changes in atmospheric CO2, drought or temperature allowed for intensive investigation of the interactions between photosynthesis and leaf, soil and ecosystem respiration. Experiments conducted in the rainforest biome have provided some of the most comprehensive dataset to date on the effects of climate change variables on tropical ecosystems. Results from these studies have been later corroborated in natural rainforest ecosystems and have improved the predictive capabilities of models that now show increased resilience of tropics to climate change. Studies of temperature and CO2 effects on ecosystem respiration and its leaf and soil components have helped reconsider the use of simple first-order kinetics for characterizing respiration in models. The B2L also provided opportunities to quantify the rhizosphere priming effect, or establish the relationships between net primary productivity, atmospheric CO2 and isoprene emissions.

  5. Effect of pH on the stability of plant phenolic compounds.

    Science.gov (United States)

    Friedman, M; Jürgens, H S

    2000-06-01

    It is not uncommon to treat plant-derived foods and feeds with alkali. Such exposure to high pH is being used to recover proteins from cereals and legumes, to induce the formation of fiber-forming meat analogue vegetable protein, for preparing peeled fruits and vegetables, and for destroying microorganisms. In addition to their profound effects on functional and nutritional properties in such foods, such treatments may also cause other side reactions, including the destruction of natural polyphenolic compounds. Because plants contain a large number of structurally different antioxidant, anticarcinogenic, and antimicrobial polyphenolic compounds, it is of interest to know whether such compounds are stable to heat and to high pH. In this model study, the stability of the following natural polyphenols to pH in the range 3-11 was studied with the aid of ultraviolet spectroscopy: caffeic acid, (-)-catechin, chlorogenic acid, ferulic acid, gallic acid, (-)-epigallocatechin, rutin, and the nonphenolic compound trans-cinnamic acid. This study demonstrates that caffeic, chlorogenic, and gallic acids are not stable to high pH and that the pH- and time-dependent spectral transformations are not reversible. By contrast, chlorogenic acid is stable to acid pH, to heat, and to storage when added to apple juice. (-)-Catechin, (-)-epigallocatechin, ferulic acid, rutin, and trans-cinnamic acid resisted major pH-induced degradation. The results are rationalized in terms of relative resonance stabilization of phenoxide ions and quinone oxidation intermediates. The possible significance of these findings to food chemistry and microbiology is discussed.

  6. Mathematical modeling of the "plant community -soil-like substrate -gas exchange with the human" closed ecosystem

    Science.gov (United States)

    Barkhatov, Yuri; Gubanov, Vladimir; Tikhomirov, Alexander A.; Degermendzhy, Andrey G.

    A mathematical model of the "plant community -soil-like substrate -gas exchange with the human" experimental biological life support system (BLSS) has been constructed to predict its functioning and estimate feasibility of controlling it. The mathematical model consists of three compartments -two `phytotron' models (with wheat and radish) and the `mycotron' model (for mushrooms). The following components are included in the model: edible mushrooms (mushroom fruit bodies and mycelium); wheat; radish; straw (processed by mycelium); dead organic matter in the phytotron (separately for the wheat unit and for the radish unit); worms; worms' coprolites; vermicompost used as a soil-like substrate (SLS); bacterial microflora; min-eral nitrogen, phosphorus and iron; products of the system intended for humans (wheat grains, radish roots and mushroom fruit bodies); oxygen and carbon dioxide. Under continuous gas exchange, the mass exchange between the compartments occurs at the harvesting time. The conveyor character of the closed ecosystem functioning has been taken into account -the num-ber of culture age groups can be regulated (in experiments -4 and 8 age groups). The conveyor cycle duration can be regulated as well. The module is designed for the food and gas exchange requirements of 1/30 of a virtually present human. Aim of model analysis is determination of investigation direction in real experimental BLSS. The model allows doing dynamic calcu-lations of closure coefficient based on the main elements taken into account in the model and evaluating all dynamic components of the system under different conditions and modes of its operation, especially under the conditions that can hardly be created experimentally. One of the sustainability conditions can be long-duration functioning of the system under the light-ing that is far from the optimum. The mathematical model of the system can demonstrate variants of its sustainable functioning or ruin under various critical

  7. Plant stimulation of soil microbial community succession: how sequential expression mediates soil carbon stabilization and turnover

    Energy Technology Data Exchange (ETDEWEB)

    Firestone, Mary [Univ. of California, Berkeley, CA (United States)

    2015-03-31

    It is now understood that most plant C is utilized or transformed by soil microorganisms en route to stabilization. Hence the composition of microbial communities that mediate decomposition and transformation of root C is critical, as are the metabolic capabilities of these communities. The change in composition and function of the C-transforming microbial communities over time in effect defines the biological component of soil C stabilization. Our research was designed to test 2 general hypotheses; the first two hypotheses are discussed first; H1: Root-exudate interactions with soil microbial populations results in the expression of enzymatic capacities for macromolecular, complex carbon decomposition; and H2: Microbial communities surrounding roots undergo taxonomic succession linked to functional gene activities as roots grow, mature, and decompose in soil. Over the term of the project we made significant progress in 1) quantifying the temporal pattern of root interactions with the soil decomposing community and 2) characterizing the role of root exudates in mediating these interactions.

  8. Stability and Sensitivity Analysis of a Plant Disease Model with Continuous Cultural Control Strategy

    Directory of Open Access Journals (Sweden)

    Zhang Zhonghua

    2014-01-01

    Full Text Available In this paper, a plant disease model with continuous cultural control strategy and time delay is formulated. Then, how the time delay affects the overall disease progression and, mathematically, how the delay affects the dynamics of the model are investigated. By analyzing the transendental characteristic equation, stability conditions related to the time delay are derived for the disease-free equilibrium. Specially, when R0=1, the Jacobi matrix of the model at the disease-free equilibrium always has a simple zero eigenvalue for all τ≥0. The center manifold reduction and the normal form theory are used to discuss the stability and the steady-state bifurcations of the model near the nonhyperbolic disease-free equilibrium. Then, the sensitivity analysis of the threshold parameter R0 and the positive equilibrium E* is carried out in order to determine the relative importance of different factors responsible for disease transmission. Finally, numerical simulations are employed to support the qualitative results.

  9. The Distribution of Microalgae in a Stabilization Pond System of a Domestic Wastewater Treatment Plant in a Tropical Environment (Case Study: Bojongsoang Wastewater Treatment Plant

    Directory of Open Access Journals (Sweden)

    Herto Dwi Ariesyady

    2016-02-01

    Full Text Available The Bojongsoang Wastewater Treatment Plant (WWTP serves to treat domestic wastewater originating from Bandung City, West Java, Indonesia. An abundant amount of nutrients as a result of waste decomposition increases the number of microalgae populations present in the pond of the wastewater treatment plant, thereby causing a population explosion of microalgae, also called algal blooming. In a stabilization pond system, the presence of algal blooming is not desirable because it can decrease wastewater treatment performance. More knowledge about the relationship between the nutrients concentration and algae blooming conditions, such as microalgae diversity, is needed to control and maintain the performance of the wastewater treatment plant. Therefore this study was conducted, in order to reveal the diversity of microalgae in the stabilization pond system and its relationship with the water characteristics of the comprising ponds. The results showed that the water quality in the stabilization pond system of Bojongsoang WWTP supported rapid growth of microalgae, where most rapid microbial growth occurred in the anaerobic pond. The microalgae diversity in the stabilization ponds was very high, with various morphologies, probably affiliated with blue-green algae, green algae, cryptophytes, dinoflagellates and diatoms. This study has successfully produced information on microalgae diversity and abundance profiles in a stabilization pond system.

  10. OXIDATIVE STABILITY OF CHILLED CHICKEN MEAT AFTER FEEDING OF SELECTED PLANTS

    Directory of Open Access Journals (Sweden)

    Mária Martonová

    2010-07-01

    Full Text Available  The effect of feeding of lemon balm (Melissa officinalis, L and combination of yarrow (Achillea millefolium L and hawthorn (Crataegus oxyacantha L on oxidative stability and sensory properties of produced poultry meat was investigated. Sixty one-day-old commercial broiler chicks (ROSS 308 were used in our experiment, divided into 3 groups, and fed 41 days, as follows: control (K was fed with standard diet without supplementation of plants; second group (M was fed with standard diet supplemented with grounded lemon balm in concentration 2 % per 1 kg; and third group was fed with standard diet supplemented with grounded yarrow (2 % and hawthorn (1 %. Results showed that supplementation with lemon balm, and mainly combination of yarrow and hawthorn in the diet significantly caused reduction of lipid oxidation processes in thigh meat during chilling storage of samples. In addition, supplementation of plants in the diet had positive effect on sensory quality of meat of broiler chickens.    doi:10.5219/38 

  11. Total Ecosystem Carbon Stock

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — Total ecosystem carbon includes above- and below-ground live plant components (such as leaf, branch, stem and root), dead biomass (such as standing dead wood, down...

  12. Tomato cystatin SlCYS8 as a stabilizing fusion partner for human serpin expression in plants.

    Science.gov (United States)

    Sainsbury, Frank; Varennes-Jutras, Philippe; Goulet, Marie-Claire; D'Aoust, Marc-André; Michaud, Dominique

    2013-12-01

    Studies have reported the usefulness of fusion proteins to bolster recombinant protein yields in plants. Here, we assess the potential of tomato SlCYS8, a Cys protease inhibitor of the cystatin protein superfamily, as a stabilizing fusion partner for human alpha-1-antichymotrypsin (α1ACT) targeted to the plant cell secretory pathway. Using the model expression platform Nicotiana benthamiana, we show that the cystatin imparts a strong stabilizing effect when expressed as a translational fusion with α1ACT, allowing impressive accumulation yields of over 2 mg/g of fresh weight tissue for the human serpin, a 25-fold improvement on the yield of α1ACT expressed alone. Natural and synthetic peptide linkers inserted between SlCYS8 and α1ACT have differential effects on protease inhibitory potency of the two protein partners in vitro. They also have a differential impact on the yield of α1ACT, dependent on the extent to which the hybrid protein may remain intact in the plant cell environment. The stabilizing effect of SlCYS8 does not involve Cys protease inhibition and can be partly reproduced in the cytosol, where peptide linkers are less susceptible to degradation. The effect of SlCYS8 on α1ACT yields could be explained by: (i) an improved translation of the human protein coding sequence; and/or (ii) an overall stabilization of its tertiary structure preventing proteolytic degradation and/or polymerization. These findings suggest the potential of plant cystatins as stabilizing fusion partners for recombinant proteins in plant systems. They also underline the need for an empirical assessment of peptide linker functions in plant cell environments.

  13. Methods to test the interactive effects of drought and plant invasion on ecosystem structure and function using complementary common garden and field experiments.

    Science.gov (United States)

    Alba, Christina; NeSmith, Julienne E; Fahey, Catherine; Angelini, Christine; Flory, Stephen Luke

    2017-03-01

    Abiotic global change drivers affect ecosystem structure and function, but how they interact with biotic factors such as invasive plants is understudied. Such interactions may be additive, synergistic, or offsetting, and difficult to predict. We present methods to test the individual and interactive effects of drought and plant invasion on native ecosystems. We coupled a factorial common garden experiment containing resident communities exposed to drought (imposed with rainout shelters) and invasion with a field experiment where the invader was removed from sites spanning a natural soil moisture gradient. We detail treatments and their effects on abiotic conditions, including soil moisture, light, temperature, and humidity, which shape community and ecosystem responses. Ambient precipitation during the garden experiment exceeded historic norms despite severe drought in prior years. Soil moisture was 48% lower in drought than ambient plots, but the invader largely offset drought effects. Additionally, temperature and light were lower and humidity higher in invaded plots. Field sites spanned up to a 10-fold range in soil moisture and up to a 2.5-fold range in light availability. Invaded and resident vegetation did not differentially mediate soil moisture, unlike in the garden experiment. Herbicide effectively removed invaded and resident vegetation, with removal having site-specific effects on soil moisture and light availability. However, light was generally higher in invader-removal than control plots, whereas resident removal had less effect on light, similar to the garden experiment. Invasion mitigated a constellation of abiotic conditions associated with drought stress in the garden experiment. In the field, where other factors co-varied, these patterns did not emerge. Still, neither experiment suggested that drought and invasion will have synergistic negative effects on ecosystems, although invasion can limit light availability. Coupling factorial garden

  14. Communities of endophytic sebacinales associated with roots of herbaceous plants in agricultural and grassland ecosystems are dominated by Serendipita herbamans sp. nov.

    Directory of Open Access Journals (Sweden)

    Kai Riess

    Full Text Available Endophytic fungi are known to be commonly associated with herbaceous plants, however, there are few studies focusing on their occurrence and distribution in plant roots from ecosystems with different land uses. To explore the phylogenetic diversity and community structure of Sebacinales endophytes from agricultural and grassland habitats under different land uses, we analysed the roots of herbaceous plants using strain isolation, polymerase chain reaction (PCR, transmission electron microscopy (TEM and co-cultivation experiments. A new sebacinoid strain named Serendipita herbamans belonging to Sebacinales group B was isolated from the roots of Bistorta vivipara, which is characterized by colourless monilioid cells (chlamydospores that become yellow with age. This species was very common and widely distributed in association with a broad spectrum of herbaceous plant families in diverse habitats, independent of land use type. Ultrastructurally, the presence of S. herbamans was detected in the cortical cells of Plantago media, Potentilla anserina and Triticum aestivum. In addition, 13 few frequent molecular operational taxonomic units (MOTUs or species were found across agricultural and grassland habitats, which did not exhibit a distinctive phylogenetic structure. Laboratory-based assays indicate that S. herbamans has the ability to colonize fine roots and stimulate plant growth. Although endophytic Sebacinales are widely distributed across agricultural and grassland habitats, TEM and nested PCR analyses reinforce the observation that these microorganisms are present in low quantity in plant roots, with no evidence of host specificity.

  15. Thermal Stability Studies of Candidate Decontamination Agents for Hanford’s Plutonium Finishing Plant Plutonium-Contaminated Gloveboxes

    Energy Technology Data Exchange (ETDEWEB)

    Scheele, Randall D.; Cooper, Thurman D.; Jones, Susan A.; Ewalt, John R.; Compton, James A.; Trent, Donald S.; Edwards, Matthew K.; Kozelisky, Anne E.; Scott, Paul A.; Minette, Michael J.

    2005-09-29

    This report provides the results of PNNL's and Fluor's studies of the thermal stabilities of potential wastes arising from decontamination of Hanford's Plutonium Finishing Plant's plutonium contaminated gloveboxes. The candidate wastes arising from the decontamination technologies ceric nitrate/nitric acid, RadPro, Glygel, and Aspigel.

  16. Woody plant encroachment, and its removal, impact bacterial and fungal communities across stream and terrestrial habitats in a tallgrass prairie ecosystem.

    Science.gov (United States)

    Veach, Allison M; Dodds, Walter K; Jumpponen, Ari

    2015-10-01

    Woody plant encroachment has become a global threat to grasslands and has caused declines in aboveground richness and changes in ecosystem function; yet we have a limited understanding on the effects of these phenomena on belowground microbial communities. We completed riparian woody plant removals at Konza Prairie Biological Station, Kansas and collected soils spanning land-water interfaces in removal and woody vegetation impacted areas. We measured stream sediments and soils for edaphic variables (C and N pools, soil water content, pH) and bacterial (16S rRNA genes) and fungal (ITS2 rRNA gene repeat) communities using Illumina MiSeq metabarcoding. Bacterial richness and diversity decreased with distance from streams. Fungal richness decreased with distance from the stream in wooded areas, but was similar across landscape position while Planctomycetes and Basidiomycota relative abundance was lower in removal areas. Cyanobacteria, Ascomycota, Chytridiomycota and Glomeromycota relative abundance was greater in removal areas. Ordination analyses indicated that bacterial community composition shifted more across land-water interfaces than fungi yet both were marginally influenced by treatment. This study highlights the impacts of woody encroachment restoration on grassland bacterial and fungal communities which likely subsequently affects belowground processes and plant health in this ecosystem. © FEMS 2015. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

  17. Linking a Large-Watershed Hydrogeochemical Model to a Wetland Community-Ecosystem Model to Estimate Plant Invasion Risk in the Coastal Great Lakes Region, USA

    Science.gov (United States)

    Currie, W. S.; Bourgeau-Chavez, L. L.; Elgersma, K. J.; French, N. H. F.; Goldberg, D. E.; Hart, S.; Hyndman, D. W.; Kendall, A. D.; Martin, S. L.; Martina, J. P.

    2014-12-01

    In the Laurentian Great Lakes region of the Upper Midwest, USA, agricultural and urban land uses together with high N deposition are contributing to elevated flows of N in rivers and groundwater to coastal wetlands. The functioning of coastal wetlands, which provide a vital link between land and water, are imperative to maintaining the health of the entire Great Lakes Basin. Elevated N inflows are believed to facilitate the spread of large-stature invasive plants (cattails and Phragmites) that reduce biodiversity and have complex effects on other ecosystem services including wetland N retention and C accretion. We enhanced the ILHM (Integrated Landscape Hydrology Model) to simulate the effects of land use on N flows in streams, rivers, and groundwater throughout the Lower Peninsula of Michigan. We used the hydroperiods and N loading rates simulated by ILHM as inputs to the Mondrian model of wetland community-ecosystem processes to estimate invasion risk and other ecosystem services in coastal wetlands around the Michigan coast. Our linked models produced threshold behavior in the success of invasive plants in response to N loading, with the threshold ranging from ca. 8 to 12 g N/m2 y, depending on hydroperiod. Plant invasions increased wetland productivity 3-fold over historically oligotrophic native communities, decreased biodiversity but slightly increased wetland N retention. Regardless of invasion, elevated N loading resulted in significantly enhanced rates of C accretion, providing an important region-wide mechanism of C storage. The linked models predicted a general pattern of greater invasion risk in the southern basins of lakes Michigan and Huron relative to northern areas. The basic mechanisms of invasion have been partially validated in our field mesocosms constructed for this project. The general regional patterns of increased invasion risk have been validated through our field campaigns and remote sensing conducted for this project.

  18. Plants grown on sewage sludge in South China and its relevance to sludge stabilization and metal removal

    Institute of Scientific and Technical Information of China (English)

    SAMAKE Moussa; WU Qi-Tang; MO Ce-hui; MOREL Jean-Louis

    2003-01-01

    The production of sewage sludge in China has been increasing sharply in order to treat 40% of the municipal sewage in 2005 as planned by central government. The main sludge disposal method is landfill owing to heavy metal contamination, but it presents an attractive potential for agricultural land application. Experiments were carried out to study the simultaneous metal removal and sludge stabilization by plants. The sludge samples were collected from Datansha Wastewater Treatment Plant of Guangzhou, it contained excessive Cu and Zn compared with the Chinese National Standard for Agricultural Use of Sewage Sludge. Plants growing on sludge beds were investigated to follow their growth and metal uptake. 30 sludge plants were identified during 1 year's observation. A Zn high-accumulating and high growth rate plant(Alocasia macrorrhiza) was selected and grown on sludge beds in plots. The water, organic matter, heavy metals and nutrients contents, the E. coli number and the cress seed germination index were monitored for the sludge samples collected monthly. The plant growth parameters and its heavy metals contents were also determined. The sewage sludge treated by plants could be stabilized at about 5 months, the E. coli number was significantly decreased and the cress seed germination index attained 100%. Crop on sludge could ameliorate the sludge drying. The experiments are continuing to find out the appropriate plant combination for simultaneous sludge stabilization and metal removal for an acceptable period. Comparisons between the proposed processes and other methods for treating produced sludge such as composting, chemical and bacterial leaching were discussed.

  19. Stability analysis of the governor-turbine-hydraulic system of pumped storage plant during small load variation

    Science.gov (United States)

    Yu, X. D.; Zhang, J.; Chen, S.; Liu, J. C.

    2016-11-01

    Governor-turbine-hydraulic (GTH) system is complex because of strong couplings of hydraulic, mechanical and electrical system. This paper presents a convenient mathematical model of the GTH system of a pumped storage plant (PSP) during small load variation. By using state space method and eigenvalue method, the stability of the GTH system is analyzed and the stable regions of the system can be given as well, which would help to optimize system design or the turning of governors. The proposed method is used to analyze the stability of a practical pumped storage plant during small load variation, which is also simulated in time domain on the basis of characteristics method. The theoretical analysis is in good agreement with numerical simulations. Based on the proposed method, the effect of the system parameters and operating conditions on the stable regions is investigated. These results are useful for the design of the GTH system of pumped storage plants.

  20. Organic plant ingredients in the diet of Rainbow trout (Oncorhynchus mykiss): Impact on fish muscle composition and oxidative stability

    DEFF Research Database (Denmark)

    Baron, Caroline P.; Svendsen, Gry Hougaard; Lund, Ivar

    2013-01-01

    of the following organic plant oils; rapeseed (RO), linseed/flaxseed (LO), grape seed (GO), or sunflower (SO). The impact of these substitutionswas investigated by measuring fish muscle fatty acid profile as well as oxidative andcolor stability of the fillet during 14 days ice storage. The inclusion of plant......Rainbow trout were fed diets containing either fish meal and fish oil (FM‐FO) (control) or diets inwhich 40% of the fishmeal was substituted with a mixture of ingredients grown organically including plant protein concentrate (PP) in combination with either fish oil (FO) as lipid source, or one...... protein concentrate did not affect the fatty acid profile significantly but resulted in a slightly improved oxidative stability of the fish fillets as compared to the control diet. The fatty acid profile of the oil used was in general well reflected in the fish muscle fatty acid profile. Fish fed PP...

  1. Hormonal and metabolic regulation of source-sink relations under salinity and drought: from plant survival to crop yield stability.

    Science.gov (United States)

    Albacete, Alfonso A; Martínez-Andújar, Cristina; Pérez-Alfocea, Francisco

    2014-01-01

    Securing food production for the growing population will require closing the gap between potential crop productivity under optimal conditions and the yield captured by farmers under a changing environment, which is termed agronomical stability. Drought and salinity are major environmental factors contributing to the yield gap ultimately by inducing premature senescence in the photosynthetic source tissues of the plant and by reducing the number and growth of the harvestable sink organs by affecting the transport and use of assimilates between and within them. However, the changes in source-sink relations induced by stress also include adaptive changes in the reallocation of photoassimilates that influence crop productivity, ranging from plant survival to yield stability. While the massive utilization of -omic technologies in model plants is discovering hundreds of genes with potential impacts in alleviating short-term applied drought and salinity stress (usually measured as plant survival), only in relatively few cases has an effect on crop yield stability been proven. However, achieving the former does not necessarily imply the latter. Plant survival only requires water status conservation and delayed leaf senescence (thus maintaining source activity) that is usually accompanied by growth inhibition. However, yield stability will additionally require the maintenance or increase in sink activity in the reproductive structures, thus contributing to the transport of assimilates from the source leaves and to delayed stress-induced leaf senescence. This review emphasizes the role of several metabolic and hormonal factors influencing not only the source strength, but especially the sink activity and their inter-relations, and their potential to improve yield stability under drought and salinity stresses.

  2. Occurrence and removal of benzotriazole ultraviolet stabilizers in a wastewater treatment plant in China.

    Science.gov (United States)

    Song, Shanjun; Ruan, Ting; Wang, Thanh; Liu, Runzeng; Jiang, Guibin

    2014-05-01

    Benzotriazole ultraviolet stabilizers (BZT-UVs) have previously been found in sludge from wastewater treatment plants (WWTPs), which might be potential sources of BZT-UVs to the surrounding environment. In this work, the occurrence and fate of seven emerging 2-hydroxyphenyl substituted BZT-UVs were investigated in a Chinese WWTP. This group of hydrophobic BZT-UVs possess log Kow values ranging from 4.31 to 7.67 which could be associated with their fate in WWTPs. Field samples including 24 h flow composites of influent, effluent and grab sludge samples from different treatment processes were collected and analyzed. Concentrations of BZT-UVs dissolved in aqueous-phases were in the range of 4.88±1.35 (UV-234) to 34.5±12.4 ng L(-1) (UV-P) in the primary influent, while only UV-P and UV-328 were detected in the final effluent at concentrations of 10.5±6.59 and 2.74±1.73 ng L(-1), respectively. Considering the amount of target BZT-UVs adsorbed to total suspended solids (TSS), the daily mass flux in the primary influent of the WWTP ranged from 22.3 g day(-1) (UV-P, 7.99%) to 74.0 g day(-1) (UV-234, 26.5%). Total removal efficiency of the integrated treatment process ranged from 89.7% for UV-P to 99.7% for UV-234 suggesting nearly complete removal. Organic solid sedimentation in primary and secondary clarifiers was the dominant elimination route for BZT-UV analogues, which constituted 96.3% of the total removal efficiency. Advanced treatment (using ultraviolet disinfection) in this plant might further contribute to the high removal efficiencies (ranging from 19.6% to 77.3%).

  3. Investigating Ecosystems in a Biobottle

    Science.gov (United States)

    Breene, Arnica; Gilewski, Donna

    2008-01-01

    Biobottles are miniature ecosystems made from 2-liter plastic soda bottles. They allow students to explore how organisms in an ecosystem are connected to each other, examine how biotic and abiotic factors influence plant and animal growth and development, and discover how important biodiversity is to an ecosystem. This activity was inspired by an…

  4. Investigating Ecosystems in a Biobottle

    Science.gov (United States)

    Breene, Arnica; Gilewski, Donna

    2008-01-01

    Biobottles are miniature ecosystems made from 2-liter plastic soda bottles. They allow students to explore how organisms in an ecosystem are connected to each other, examine how biotic and abiotic factors influence plant and animal growth and development, and discover how important biodiversity is to an ecosystem. This activity was inspired by an…

  5. Ecosystem development after mangrove creation: plant-soil change across a twenty-year chronosequence in Tampa Bay, FL

    Science.gov (United States)

    On a global scale, the loss of mangroves has been high (~1-2% loss per year in recent decades). Recognizing the important ecosystem services supported by mangroves, restoration and creation efforts are increasingly proposed as mechanisms to replace those services lost after mangr...

  6. Restoring longleaf pine wiregrass ecosystems: plant cover, diversity and biomass following low-rate hexazinone application on Florida sandhills

    Science.gov (United States)

    Dale G. Brockway; Kenneth W. Outcalt; R. Neal. Wilkins

    1998-01-01

    A longleaf pine wiregrass ecosystem in the sandhills of north central Florida, upon which turkey oak gained dominance following a wildfire, was treated with low rate (1.1 or 2.2 kg/ha) applications of the herbicide hexazinone during the 1991 growing season. All applications successfully reduced oak in the overstory and understory, mortality ranging from 83 to 93...

  7. Micro-topographic variation in soil respiration and its controlling factors vary with plant phenophases in a desert-shrub ecosystem

    Directory of Open Access Journals (Sweden)

    B. Wang

    2015-06-01

    Full Text Available Soil respiration (Rs and its biophysical controls were measured over a fixed sand dune in a desert-shrub ecosystem in northwest China in 2012 to explore the mechanisms controlling the spatial heterogeneity in Rs and to understand the plant effects on the spatial variation in Rs in different phenophases. The measurements were carried out on four slope orientations (i.e., windward, leeward, north- and south-face and three height positions on each slope (i.e., lower, upper, and top across the phenophases of the dominant shrub species (Artemisia ordosica. Coefficient of variation (i.e., standard deviation/mean of Rs across the 11 microsites over our measurement period was 23.5 %. Soil respiration was highest on the leeward slope, but lowest on the windward slope. Over the measurement period, plant-related factors, rather than micro-hydrometeorological factors, affected the topographic variation in Rs. During the flowering-bearing phase, root biomass affected Rs most, explaining 72 % of the total variation. During the leaf coloration-defoliation phase, soil nitrogen content affected Rs the most, explaining 56 % of the total variation. Our findings highlight that spatial pattern in Rs was dependent on plant distribution over a desert sand dune, and plant-related factors largely regulated topographic variation in Rs, and such regulations varied with plant phenology.

  8. Depletion of stratospheric ozone over the Antarctic and Arctic: Responses of plants of polar terrestrial ecosystems to enhanced UV-B, an overview

    Energy Technology Data Exchange (ETDEWEB)

    Rozema, Jelte [Department of Systems Ecology, Institute of Ecological Science, Climate Centre, Vrije Universiteit, De Boelelaan 1087, 1081 HV Amsterdam (Netherlands)]. E-mail: jelte.rozema@ecology.falw.vu.nl; Boelen, Peter [Department of Systems Ecology, Institute of Ecological Science, Climate Centre, Vrije Universiteit, De Boelelaan 1087, 1081 HV Amsterdam (Netherlands); Blokker, Peter [Department of Systems Ecology, Institute of Ecological Science, Climate Centre, Vrije Universiteit, De Boelelaan 1087, 1081 HV Amsterdam (Netherlands)

    2005-10-15

    Depletion of stratospheric ozone over the Antarctic has been re-occurring yearly since 1974, leading to enhanced UV-B radiation. Arctic ozone depletion has been observed since 1990. Ozone recovery has been predicted by 2050, but no signs of recovery occur. Here we review responses of polar plants to experimentally varied UV-B through supplementation or exclusion. In supplementation studies comparing ambient and above ambient UV-B, no effect on growth occurred. UV-B-induced DNA damage, as measured in polar bryophytes, is repaired overnight by photoreactivation. With UV exclusion, growth at near ambient may be less than at below ambient UV-B levels, which relates to the UV response curve of polar plants. UV-B screening foils also alter PAR, humidity, and temperature and interactions of UV with environmental factors may occur. Plant phenolics induced by solar UV-B, as in pollen, spores and lignin, may serve as a climate proxy for past UV. Since the Antarctic and Arctic terrestrial ecosystems differ essentially (e.g. higher species diversity and more trophic interactions in the Arctic), generalization of polar plant responses to UV-B needs caution. - Polar plant responses to UV-B may be different in the Arctic than Antarctic regions.

  9. Methylotrophic bacteria symbiosis with the higher plants as means of minimization of the lower hydrocarbons concentration during artificial ecosystem gas exchange

    Science.gov (United States)

    Berkovich, Yuliy; Smolyanina, Svetlana; Moukhamedieva, Lana; Mardanov, Robert; Doronina, Nina; Ivanova, Ekaterina

    Plant growth unit should be included in the LSS for the space vehicles for vitamin greens supply and psychological support of cosmonauts during long-term missions. The lower hydrocarbons such as methane, methanol, methylated sulfuric compounds and methylated amines, ethylene and so on, are the natural products of human and plant metabolism and usually considered as the air pollutions. It is shown, that one way to decrease the lower hydrocarbons concentration in the artificial ecosystems could be colonization of the plants by methylotrophic bacteria. The aerobic methylotrophic bacteria possess unique ability to use methane and its oxidized or replaced derivatives without food damage and human, animals or plants infection. We have found that methylotrophic bacteria are the phyto-symbiotic bacteria: they stimulate growth and development of the colonized plants because of synthesizing cytokinins and auxins, and vitamin B12.Two collection strains of the obligate methylotrophic bacteria - Methylovorus mays C and Methylomonas metanica S - were chosen because of their high activity to assimilate the lower hydrocarbons due to functioning of methanoldehydrogenase, methanmonooxigenase and ribulose monophosphate cycle enzymes system.Colonization of the leaf cabbage Brassica chinensis L. by these strains led to approximately 30 % reduce of methanol and methane concentration in the air inside phytotron. Experimental estimations of the influence of methylotrophic bacteria on leafy greens growth and development are obtained.

  10. Characterization, stability, and plant effects of kiln-produced wheat straw biochar.

    Science.gov (United States)

    O'Toole, A; Knoth de Zarruk, K; Steffens, M; Rasse, D P

    2013-01-01

    Biochar is a promising technology for improving soil quality and sequestering C in the long term. Although modern pyrolysis technologies are being developed, kiln technologies often remain the most accessible method for biochar production. The objective of the present study was to assess biochar characteristics, stability in soil, and agronomic effects of a kiln-produced biochar. Wheat-straw biochar was produced in a double-barrel kiln and analyzed by solid-state C nuclear magneticresonance spectroscopy. Two experiments were conducted with biochar mixed into an Ap-horizon sandy loam. In the first experiment, CO efflux was monitored for 3 mo in plant-free soil columns across four treatments (0, 10, 50, and 100 Mg biochar ha). In the second experiment, ryegrass was grown in pots having received 17 and 54 Mg biochar ha combined with four N rates from 144 to 288 kg N ha. Our kiln method generated a wheat-straw biochar with carbon content composed of 92% of aromatic structures. Our results suggest that the biochar lost impact on ryegrass yields.

  11. Effects of Alien Plants on Ecosystem Structure and Functioning and Implications for Restoration: Insights from Three Degraded Sites in South African Fynbos

    Science.gov (United States)

    Gaertner, Mirijam; Richardson, David M.; Privett, Sean D. J.

    2011-07-01

    We investigated the type and extent of degradation at three sites on the Agulhas Plain, South Africa: an old field dominated by the alien grass Pennisetum clandestinum Pers . (kikuyu), an abandoned Eucalyptus plantation, and a natural fynbos community invaded by nitrogen fixing—Australian Acacia species. These forms of degradation are representative of many areas in the region. By identifying the nature and degree of ecosystem degradation we aimed to determine appropriate strategies for restoration in this biodiversity hotspot. Vegetation surveys were conducted at degraded sites and carefully selected reference sites. Soil-stored propagule seed banks and macro- and micro-soil nutrients were determined. Species richness, diversity and native cover under Eucalyptus were extremely low compared to the reference site and alterations of the soil nutrients were the most severe. The cover of indigenous species under Acacia did not differ significantly from that in reference sites, but species richness was lower under Acacia and soils were considerably enriched. Native species richness was much lower in the kikuyu site, but soil nutrient status was similar to the reference site. Removal of the alien species alone may be sufficient to re-initiate ecosystem recovery at the kikuyu site, whereas active restoration is required to restore functioning ecosystems dominated by native species in the Acacia thicket and the Eucalyptus plantation. To restore native plant communities we suggest burning, mulching with sawdust and sowing of native species.

  12. Floating plant dominance as a stable state

    Science.gov (United States)

    Scheffer, Marten; Szabó, Sándor; Gragnani, Alessandra; van Nes, Egbert H.; Rinaldi, Sergio; Kautsky, Nils; Norberg, Jon; Roijackers, Rudi M. M.; Franken, Rob J. M.

    2003-01-01

    Invasion by mats of free-floating plants is among the most important threats to the functioning and biodiversity of freshwater ecosystems ranging from temperate ponds and ditches to tropical lakes. Dark, anoxic conditions under thick floating-plant cover leave little opportunity for animal or plant life, and they can have large negative impacts on fisheries and navigation in tropical lakes. Here, we demonstrate that floating-plant dominance can be a self-stabilizing ecosystem state, which may explain its notorious persistence in many situations. Our results, based on experiments, field data, and models, represent evidence for alternative domains of attraction in ecosystems. An implication of our findings is that nutrient enrichment reduces the resilience of freshwater systems against a shift to floating-plant dominance. On the other hand, our results also suggest that a single drastic harvest of floating plants can induce a permanent shift to an alternative state dominated by rooted, submerged growth forms. PMID:12634429

  13. Salt marsh-mangrove ecotones: using structural gradients to investigate the effects of woody plant encroachment on plant-soil interactions and ecosystem carbon pools

    Science.gov (United States)

    Yando, Erik S.; Osland, Michael J.; Willis, Jonathan M; Day, Richard H.; Krauss, Ken W.; Hester, Mark W.

    2016-01-01

    Changing winter climate extremes are expected to result in the poleward migration of mangrove forests at the expense of salt marshes. Although mangroves and marshes are both h