WorldWideScience

Sample records for plant community responses

  1. Plant community responses to climate change

    Energy Technology Data Exchange (ETDEWEB)

    Kongstad, J.

    2012-07-01

    ecosystem more resilient to the climatic treatments than expected. We also found that the amount of flowering culms of D. flexuosa increased in response to increased CO{sub 2}, whereas the seed germination success decreased. The bryophyte biomass and the nitrogen content decreased in response to nitrogen addition. Even such apparently minor changes might, given time, affect the plant composition and thereby possibly also the major ecosystem processes. Further, we observed changes in the aboveground plant composition in response to the climate manipulations at the Mols site, where C. vulgaris was regenerating after a disturbance. Here a decrease in biomass of the pioneer stage was seen, when subjected to the drought treatment compared to warmed and control treatments. I therefore conclude, that the stage of the C. vulgaris population as well as the magnitude and frequency of disturbances determine the effects of future climate change on the plant community in heathland ecosystems. (Author)

  2. Native plant community response to alien plant invasion and removal

    Directory of Open Access Journals (Sweden)

    Jara ANDREU

    2011-01-01

    Full Text Available Given the potential ecological impacts of invasive species, removal of alien plants has become an important management challenge and a high priority for environmental managers. To consider that a removal effort has been successful requires both, the effective elimination of alien plants and the restoration of the native plant community back to its historical composition and function. We present a conceptual framework based on observational and experimental data that compares invaded, non-invaded and removal sites to quantify invaders’ impacts and native plant recover after their removal. We also conduct a meta-analysis to quantitatively evaluate the impacts of plant invaders and the consequences of their removal on the native plant community, across a variety of ecosystems around the world. Our results that invasion by alien plants is responsible for a local decline in native species richness and abundance. Our analysis also provides evidence that after removal, the native vegetation has the potential to recover to a pre-invasion target state. Our review reveal that observational and experimental approaches are rarely used in concert, and that reference sites are scarcely employed to assess native species recovery after removal. However, we believe that comparing invaded, non-invaded and removal sites offer the opportunity to obtain scientific information with relevance for management.

  3. Plant community mediation of ecosystem responses to global change factors

    Science.gov (United States)

    Churchill, A. C.

    2017-12-01

    Human alteration of the numerous environmental drivers affecting ecosystem processes is unprecedented in the last century, including changes in climate regimes and rapid increases in the availability of biologically active nitrogen (N). Plant communities may offer stabilizing or amplifying feedbacks mediating potential ecosystem responses to these alterations, and my research seeks to examine the conditions associated with when plant feedbacks are important for ecosystem change. My dissertation research focused on the unintended consequences of N deposition into natural landscapes, including alpine ecosystems which are particularly susceptible to adverse environmental impacts. In particular, I examined alpine plant and soil responses to N deposition 1) across multiple spatial scales throughout the Southern Rocky Mountains, 2) among diverse plant communities associated with unique environmental conditions common in the alpine of this region, and 3) among ecosystem pools of N contributing to stabilization of N inputs within those communities. I found that communities responded to inputs of N differently, often associated with traits of dominant plant species but these responses were intimately linked with the abiotic conditions of each independent community. Even so, statistical models predicting metrics of N processing in the alpine were improved by encompassing both abiotic and biotic components of the main community types.

  4. Response of native insect communities to invasive plants.

    Science.gov (United States)

    Bezemer, T Martijn; Harvey, Jeffrey A; Cronin, James T

    2014-01-01

    Invasive plants can disrupt a range of trophic interactions in native communities. As a novel resource they can affect the performance of native insect herbivores and their natural enemies such as parasitoids and predators, and this can lead to host shifts of these herbivores and natural enemies. Through the release of volatile compounds, and by changing the chemical complexity of the habitat, invasive plants can also affect the behavior of native insects such as herbivores, parasitoids, and pollinators. Studies that compare insects on related native and invasive plants in invaded habitats show that the abundance of insect herbivores is often lower on invasive plants, but that damage levels are similar. The impact of invasive plants on the population dynamics of resident insect species has been rarely examined, but invasive plants can influence the spatial and temporal dynamics of native insect (meta)populations and communities, ultimately leading to changes at the landscape level.

  5. Herbicide and fertilizers promote analogous phylogenetic responses but opposite functional responses in plant communities

    DEFF Research Database (Denmark)

    Pellissier, Loïc; Wisz, Mary S.; Strandberg, Beate

    2014-01-01

    on long-term experiment we show that fertilizer and herbicides (glyphosate) have contrasting effects on functional structure, but can increase phylogenetic diversity in semi-natural plant communities. We found that an increase in nitrogen promoted an increase in the average specific leaf area and canopy...... height at the community level, but an increase in glyphosate promoted a decrease in those traits. Phylogenetic diversity of plant communities increased when herbicide and fertilizer were applied together, likely because functional traits facilitating plant success in those conditions were......Throughout the world, herbicides and fertilizers change species composition in agricultural communities, but how do the cumulative effects of these chemicals impact the functional and phylogenetic structure of non-targeted communities when they drift into adjacent semi-natural habitats? Based...

  6. Burn Severity Dominates Understory Plant Community Response to Fire in Xeric Jack Pine Forests

    Directory of Open Access Journals (Sweden)

    Bradley D. Pinno

    2016-04-01

    Full Text Available Fire is the most common disturbance in northern boreal forests, and large fires are often associated with highly variable burn severities across the burnt area. We studied the understory plant community response to a range of burn severities and pre-fire stand age four growing seasons after the 2011 Richardson Fire in xeric jack pine forests of northern Alberta, Canada. Burn severity had the greatest impact on post-fire plant communities, while pre-fire stand age did not have a significant impact. Total plant species richness and cover decreased with disturbance severity, such that the greatest richness was in low severity burns (average 28 species per 1-m2 quadrat and plant cover was lowest in the high severity burns (average 16%. However, the response of individual plant groups differed. Lichens and bryophytes were most common in low severity burns and were effectively eliminated from the regenerating plant community at higher burn severities. In contrast, graminoid cover and richness were positively related to burn severity, while forbs did not respond significantly to burn severity, but were impacted by changes in soil chemistry with increased cover at pH >4.9. Our results indicate the importance of non-vascular plants to the overall plant community in this harsh environment and that the plant community is environmentally limited rather than recruitment or competition limited, as is often the case in more mesic forest types. If fire frequency and severity increase as predicted, we may see a shift in plant communities from stress-tolerant species, such as lichens and ericaceous shrubs, to more colonizing species, such as certain graminoids.

  7. Lags in the response of mountain plant communities to climate change

    DEFF Research Database (Denmark)

    Alexander, Jake M; Chalmandrier, Loïc; Lenoir, Jonathan

    2018-01-01

    Rapid climatic changes and increasing human influence at high elevations around the world will have profound impacts on mountain biodiversity. However, forecasts from statistical models (e.g. species distribution models) rarely consider that plant community changes could substantially lag behind...... plant species' spread along elevational gradients, "establishment lags" following their arrival in recipient communities, and "extinction lags" of resident species. Variation in lags is explained by variation among species in physiological and demographic responses, by effects of altered biotic...... turnover in future communities might lag behind simple expectations based on species' range shifts with unlimited dispersal. The model shows a combined contribution of altered biotic interactions and dispersal lags to plant community turnover along an elevational gradient following climate warming. Our...

  8. Plant Community and Soil Environment Response to Summer Fire in the Northern Great Plains

    Science.gov (United States)

    Fire is a keystone process in many ecosystems, especially grasslands. However, documentation of plant community and soil environment responses to fire is limited for semiarid grasslands relative to that for mesic grasslands. Replicated summer fire research is lacking, but much needed because summe...

  9. Herbicide and fertilizers promote analogous phylogenetic responses but opposite functional responses in plant communities

    International Nuclear Information System (INIS)

    Pellissier, Loïc; Wisz, Mary S; Strandberg, Beate; Damgaard, Christian

    2014-01-01

    Throughout the world, herbicides and fertilizers change species composition in agricultural communities, but how do the cumulative effects of these chemicals impact the functional and phylogenetic structure of non-targeted communities when they drift into adjacent semi-natural habitats? Based on long-term experiment we show that fertilizer and herbicides (glyphosate) have contrasting effects on functional structure, but can increase phylogenetic diversity in semi-natural plant communities. We found that an increase in nitrogen promoted an increase in the average specific leaf area and canopy height at the community level, but an increase in glyphosate promoted a decrease in those traits. Phylogenetic diversity of plant communities increased when herbicide and fertilizer were applied together, likely because functional traits facilitating plant success in those conditions were not phylogenetically conserved. Species richness also decreased with increasing levels of nitrogen and glyphosate. Our results suggest that predicting the cumulative effects of agrochemicals is more complex than anticipated due to their distinct selection of traits that may or may not be conserved phylogenetically. Precautionary efforts to mitigate drift of agricultural chemicals into semi-natural habitats are warranted to prevent unforeseeable biodiversity shifts. (paper)

  10. Plant community responses to simultaneous changes in temperature, nitrogen availability, and invasion.

    Directory of Open Access Journals (Sweden)

    Elise S Gornish

    Full Text Available Increasing rates of change in climate have been observed across the planet and have contributed to the ongoing range shifts observed for many species. Although ecologists are now using a variety of approaches to study how much and through what mechanisms increasing temperature and nutrient pollution may influence the invasions inherent in range shifts, accurate predictions are still lacking.In this study, we conducted a factorial experiment, simultaneously manipulating warming, nitrogen addition and introduction of Pityopsis aspera, to determine how range-shifting species affect a plant community. We quantified the resident community using ordination scores, then used structural equation modeling to examine hypotheses related to how plants respond to a network of experimental treatments and environmental variables. Variation in soil pH explained plant community response to nitrogen addition in the absence of invasion. However, in the presence of invasion, the direct effect of nitrogen on the community was negligible and soil moisture was important for explaining nitrogen effects. We did not find effects of warming on the native plant community in the absence of invasion. In the presence of invasion, however, warming had negative effects on functional richness directly and invasion and herbivory explained the overall positive effect of warming on the plant community.This work highlights the variation in the biotic and abiotic factors responsible for explaining independent and collective climate change effects over a short time scale. Future work should consider the complex and non-additive relationships among factors of climate change and invasion in order to capture more ecologically relevant features of our changing environment.

  11. Community emergency response to nuclear power plant accidents: A selected and partially annotated bibliography

    Energy Technology Data Exchange (ETDEWEB)

    Youngen, G.

    1988-10-01

    The role of responding to emergencies at nuclear power plants is often considered the responsibility of the personnel onsite. This is true for most, if not all, of the incidents that may happen during the course of the plant`s operating lifetime. There is however, the possibility of a major accident occurring at anytime. Major nuclear accidents at Chernobyl and Three Mile Island have taught their respective countries and communities a significant lesson in local emergency preparedness and response. Through these accidents, the rest of the world can also learn a great deal about planning, preparing and responding to the emergencies unique to nuclear power. This bibliography contains books, journal articles, conference papers and government reports on emergency response to nuclear power plant accidents. It does not contain citations for ``onsite`` response or planning, nor does it cover the areas of radiation releases from transportation accidents. The compiler has attempted to bring together a sampling of the world`s collective written experience on dealing with nuclear reactor accidents on the sate, local and community levels. Since the accidents at Three Mile Island and Chernobyl, that written experience has grown enormously.

  12. Lags in the response of mountain plant communities to climate change.

    Science.gov (United States)

    Alexander, Jake M; Chalmandrier, Loïc; Lenoir, Jonathan; Burgess, Treena I; Essl, Franz; Haider, Sylvia; Kueffer, Christoph; McDougall, Keith; Milbau, Ann; Nuñez, Martin A; Pauchard, Aníbal; Rabitsch, Wolfgang; Rew, Lisa J; Sanders, Nathan J; Pellissier, Loïc

    2018-02-01

    Rapid climatic changes and increasing human influence at high elevations around the world will have profound impacts on mountain biodiversity. However, forecasts from statistical models (e.g. species distribution models) rarely consider that plant community changes could substantially lag behind climatic changes, hindering our ability to make temporally realistic projections for the coming century. Indeed, the magnitudes of lags, and the relative importance of the different factors giving rise to them, remain poorly understood. We review evidence for three types of lag: "dispersal lags" affecting plant species' spread along elevational gradients, "establishment lags" following their arrival in recipient communities, and "extinction lags" of resident species. Variation in lags is explained by variation among species in physiological and demographic responses, by effects of altered biotic interactions, and by aspects of the physical environment. Of these, altered biotic interactions could contribute substantially to establishment and extinction lags, yet impacts of biotic interactions on range dynamics are poorly understood. We develop a mechanistic community model to illustrate how species turnover in future communities might lag behind simple expectations based on species' range shifts with unlimited dispersal. The model shows a combined contribution of altered biotic interactions and dispersal lags to plant community turnover along an elevational gradient following climate warming. Our review and simulation support the view that accounting for disequilibrium range dynamics will be essential for realistic forecasts of patterns of biodiversity under climate change, with implications for the conservation of mountain species and the ecosystem functions they provide. © 2017 John Wiley & Sons Ltd.

  13. Lags in the response of mountain plant communities to climate change

    Science.gov (United States)

    Alexander, Jake M.; Chalmandrier, Loïc; Lenoir, Jonathan; Burgess, Treena I.; Essl, Franz; Haider, Sylvia; Kueffer, Christoph; McDougall, Keith; Milbau, Ann; Nuñez, Martin A.; Pauchard, Aníbal; Rabitsch, Wolfgang; Rew, Lisa J.; Sanders, Nathan J.; Pellissier, Loïc

    2018-01-01

    Rapid climatic changes and increasing human influence at high elevations around the world will have profound impacts on mountain biodiversity. However, forecasts from statistical models (e.g. species distribution models) rarely consider that plant community changes could substantially lag behind climatic changes, hindering our ability to make temporally realistic projections for the coming century. Indeed, the magnitudes of lags, and the relative importance of the different factors giving rise to them, remain poorly understood. We review evidence for three types of lag: “dispersal lags” affecting plant species’ spread along elevational gradients, “establishment lags” following their arrival in recipient communities, and “extinction lags” of resident species. Variation in lags is explained by variation among species in physiological and demographic responses, by effects of altered biotic interactions, and by aspects of the physical environment. Of these, altered biotic interactions could contribute substantially to establishment and extinction lags, yet impacts of biotic interactions on range dynamics are poorly understood. We develop a mechanistic community model to illustrate how species turnover in future communities might lag behind simple expectations based on species’ range shifts with unlimited dispersal. The model shows a combined contribution of altered biotic interactions and dispersal lags to plant community turnover along an elevational gradient following climate warming. Our review and simulation support the view that accounting for disequilibrium range dynamics will be essential for realistic forecasts of patterns of biodiversity under climate change, with implications for the conservation of mountain species and the ecosystem functions they provide. PMID:29112781

  14. Responses of prairie arthropod communities to fire and fertilizer: Balancing plant and arthropod conservation

    Science.gov (United States)

    Hartley, M.K.; Rogers, W.E.; Siemann, E.; Grace, J.

    2007-01-01

    Fire is an important tool for limiting woody plant invasions into prairies, but using fire management to maintain grassland plant communities may inadvertently reduce arthropod diversity. To test this, we established twenty-four 100 m2 plots in a tallgrass prairie in Galveston County, Texas, in spring 2000. Plots were assigned a fire (no burn, one time burn [2000], two time burn [2000, 2001]) and fertilization treatment (none, NPK addition) in a full factorial design. Fertilization treatments allowed us to examine the effects of fire at a different level of productivity. We measured plant cover by species and sampled arthropods with sweep nets during the 2001 growing season. Path analysis indicated that fertilization reduced while annual fires increased arthropod diversity via increases and decreases in woody plant abundance, respectively. There was no direct effect of fire on arthropod diversity or abundance. Diptera and Homoptera exhibited particularly strong positive responses to fires. Lepidoptera had a negative response to nutrient enrichment. Overall, the negative effects of fire on the arthropod community were minor in contrast to the strong positive indirect effects of small-scale burning on arthropod diversity if conservation of particular taxa is not a priority. The same fire regime that minimized woody plant invasion also maximized arthropod diversity.

  15. Community emergency response to nuclear power plant accidents: A selected and partially annotated bibliography

    International Nuclear Information System (INIS)

    Youngen, G.

    1988-10-01

    The role of responding to emergencies at nuclear power plants is often considered the responsibility of the personnel onsite. This is true for most, if not all, of the incidents that may happen during the course of the plant's operating lifetime. There is however, the possibility of a major accident occurring at anytime. Major nuclear accidents at Chernobyl and Three Mile Island have taught their respective countries and communities a significant lesson in local emergency preparedness and response. Through these accidents, the rest of the world can also learn a great deal about planning, preparing and responding to the emergencies unique to nuclear power. This bibliography contains books, journal articles, conference papers and government reports on emergency response to nuclear power plant accidents. It does not contain citations for ''onsite'' response or planning, nor does it cover the areas of radiation releases from transportation accidents. The compiler has attempted to bring together a sampling of the world's collective written experience on dealing with nuclear reactor accidents on the sate, local and community levels. Since the accidents at Three Mile Island and Chernobyl, that written experience has grown enormously

  16. Taxonomic and Functional Responses of Soil Microbial Communities to Annual Removal of Aboveground Plant Biomass

    Science.gov (United States)

    Guo, Xue; Zhou, Xishu; Hale, Lauren; Yuan, Mengting; Feng, Jiajie; Ning, Daliang; Shi, Zhou; Qin, Yujia; Liu, Feifei; Wu, Liyou; He, Zhili; Van Nostrand, Joy D.; Liu, Xueduan; Luo, Yiqi; Tiedje, James M.; Zhou, Jizhong

    2018-01-01

    Clipping, removal of aboveground plant biomass, is an important issue in grassland ecology. However, few studies have focused on the effect of clipping on belowground microbial communities. Using integrated metagenomic technologies, we examined the taxonomic and functional responses of soil microbial communities to annual clipping (2010–2014) in a grassland ecosystem of the Great Plains of North America. Our results indicated that clipping significantly (P microbial respiration rates. Annual temporal variation within the microbial communities was much greater than the significant changes introduced by clipping, but cumulative effects of clipping were still observed in the long-term scale. The abundances of some bacterial and fungal lineages including Actinobacteria and Bacteroidetes were significantly (P microbial communities were significantly correlated with soil respiration and plant productivity. Intriguingly, clipping effects on microbial function may be highly regulated by precipitation at the interannual scale. Altogether, our results illustrated the potential of soil microbial communities for increased soil organic matter decomposition under clipping land-use practices. PMID:29904372

  17. Riparian plant community responses to increased flooding: a meta-analysis.

    Science.gov (United States)

    Garssen, Annemarie G; Baattrup-Pedersen, Annette; Voesenek, Laurentius A C J; Verhoeven, Jos T A; Soons, Merel B

    2015-08-01

    A future higher risk of severe flooding of streams and rivers has been projected to change riparian plant community composition and species richness, but the extent and direction of the expected change remain uncertain. We conducted a meta-analysis to synthesize globally available experimental evidence and assess the effects of increased flooding on (1) riparian adult plant and seedling survival, (2) riparian plant biomass and (3) riparian plant species composition and richness. We evaluated which plant traits are of key importance for the response of riparian plant species to flooding. We identified and analysed 53 papers from ISI Web of Knowledge which presented quantitative experimental results on flooding treatments and corresponding control situations. Our meta-analysis demonstrated how longer duration of flooding, greater depth of flooding and, particularly, their combination reduce seedling survival of most riparian species. Plant height above water level, ability to elongate shoots and plasticity in root porosity were decisive for adult plant survival and growth during longer periods of flooding. Both 'quiescence' and 'escape' proved to be successful strategies promoting riparian plant survival, which was reflected in the wide variation in survival (full range between 0 and 100%) under fully submerged conditions, while plants that protrude above the water level (>20 cm) almost all survive. Our survey confirmed that the projected increase in the duration and depth of flooding periods is sufficient to result in species shifts. These shifts may lead to increased or decreased riparian species richness depending on the nutrient, climatic and hydrological status of the catchment. Species richness was generally reduced at flooded sites in nutrient-rich catchments and sites that previously experienced relatively stable hydrographs (e.g. rain-fed lowland streams). Species richness usually increased at sites in desert and semi-arid climate regions (e.g. intermittent

  18. Plant community structure regulates responses of prairie soil respiration to decadal experimental warming.

    Science.gov (United States)

    Xu, Xia; Shi, Zheng; Li, Dejun; Zhou, Xuhui; Sherry, Rebecca A; Luo, Yiqi

    2015-10-01

    Soil respiration is recognized to be influenced by temperature, moisture, and ecosystem production. However, little is known about how plant community structure regulates responses of soil respiration to climate change. Here, we used a 13-year field warming experiment to explore the mechanisms underlying plant community regulation on feedbacks of soil respiration to climate change in a tallgrass prairie in Oklahoma, USA. Infrared heaters were used to elevate temperature about 2 °C since November 1999. Annual clipping was used to mimic hay harvest. Our results showed that experimental warming significantly increased soil respiration approximately from 10% in the first 7 years (2000-2006) to 30% in the next 6 years (2007-2012). The two-stage warming stimulation of soil respiration was closely related to warming-induced increases in ecosystem production over the years. Moreover, we found that across the 13 years, warming-induced increases in soil respiration were positively affected by the proportion of aboveground net primary production (ANPP) contributed by C3 forbs. Functional composition of the plant community regulated warming-induced increases in soil respiration through the quantity and quality of organic matter inputs to soil and the amount of photosynthetic carbon (C) allocated belowground. Clipping, the interaction of clipping with warming, and warming-induced changes in soil temperature and moisture all had little effect on soil respiration over the years (all P > 0.05). Our results suggest that climate warming may drive an increase in soil respiration through altering composition of plant communities in grassland ecosystems. © 2015 John Wiley & Sons Ltd.

  19. Nematode community shifts in response to experimental warming and canopy conditions are associated with plant community changes in the temperate-boreal forest ecotone.

    Science.gov (United States)

    Thakur, Madhav Prakash; Reich, Peter B; Fisichelli, Nicholas A; Stefanski, Artur; Cesarz, Simone; Dobies, Tomasz; Rich, Roy L; Hobbie, Sarah E; Eisenhauer, Nico

    2014-06-01

    Global climate warming is one of the key forces driving plant community shifts, such as range shifts of temperate species into boreal forests. As plant community shifts are slow to observe, ecotones, boundaries between two ecosystems, are target areas for providing early evidence of ecological responses to warming. The role of soil fauna is poorly explored in ecotones, although their positive and negative effects on plant species can influence plant community structure. We studied nematode communities in response to experimental warming (ambient, +1.7, +3.4 °C) in soils of closed and open canopy forest in the temperate-boreal ecotone of Minnesota, USA and calculated various established nematode indices. We estimated species-specific coverage of understory herbaceous and shrub plant species from the same experimental plots and tested if changes in the nematode community are associated with plant cover and composition. Individual nematode trophic groups did not differ among warming treatments, but the ratio between microbial-feeding and plant-feeding nematodes increased significantly and consistently with warming in both closed and open canopy areas and at both experimental field sites. The increase in this ratio was positively correlated with total cover of understory plant species, perhaps due to increased predation pressure on soil microorganisms causing higher nutrient availability for plants. Multivariate analyses revealed that temperature treatment, canopy conditions and nematode density consistently shaped understory plant communities across experimental sites. Our findings suggest that warming-induced changes in nematode community structure are associated with shifts in plant community composition and productivity in the temperate-boreal forest ecotones.

  20. [Species, functional, structural diversity of typical plant communities and their responses to environmental factors in Miao Archipelago, China.

    Science.gov (United States)

    Zheng, Li Ting; Su, Tian; Liu, Xiang Yu; Yin, Fang; Guo, Chao; Tuo, Bin; Yan, En Rong

    2018-02-01

    Island vegetation plays an important role in biodiversity research across the world. The study of plant diversity in island is helpful for understanding the mechanism of plant diversity maintenance under land-sea interaction. Here, four typical plant communities (Quercus acutissima community, Robinia pseudoacacia community, Pinus thunbergii community and Vitex negundo community) in Miao Archipelago were selected to examine the species, functional and structural diversities and their responses to environmental factors at the community scale by using species diversity indices, functional diversity indices, as well as structural diversity indices. The results showed that the species richness and Rao index of P. thunbergii community was higher than that of Q. acutissima community and R. pseudoacacia community, but the structural diversity was lower. The species diversity and structural diversity of V. Negundo shrub were lower than that of forest community, but the functional diversity was higher than some forest communities. The relationship between the diversity of typical plant communities in island area illustrated a significant positive correlation between species richness with Rao index and tree height diversity, however the correlation with functional evenness was significantly negative. The structural diversity and functional evenness were determined by slope with negative and positive relationships, respectively. Functional heterogeneity, functional divergence and species diversity were affected largely by soil physical and chemical properties, displaying the positive relationship with soil bulk density and soil total carbon content, and a negative relationship with soil water content. In conclusion, diversity pattern of plant community in Miao Archipelago reflected not only the characteristics in mainland vegetation but also the special nature of the sea island.

  1. Predictive occurrence models for coastal wetland plant communities: delineating hydrologic response surfaces with multinomial logistic regression

    Science.gov (United States)

    Snedden, Gregg A.; Steyer, Gregory D.

    2013-01-01

    Understanding plant community zonation along estuarine stress gradients is critical for effective conservation and restoration of coastal wetland ecosystems. We related the presence of plant community types to estuarine hydrology at 173 sites across coastal Louisiana. Percent relative cover by species was assessed at each site near the end of the growing season in 2008, and hourly water level and salinity were recorded at each site Oct 2007–Sep 2008. Nine plant community types were delineated with k-means clustering, and indicator species were identified for each of the community types with indicator species analysis. An inverse relation between salinity and species diversity was observed. Canonical correspondence analysis (CCA) effectively segregated the sites across ordination space by community type, and indicated that salinity and tidal amplitude were both important drivers of vegetation composition. Multinomial logistic regression (MLR) and Akaike's Information Criterion (AIC) were used to predict the probability of occurrence of the nine vegetation communities as a function of salinity and tidal amplitude, and probability surfaces obtained from the MLR model corroborated the CCA results. The weighted kappa statistic, calculated from the confusion matrix of predicted versus actual community types, was 0.7 and indicated good agreement between observed community types and model predictions. Our results suggest that models based on a few key hydrologic variables can be valuable tools for predicting vegetation community development when restoring and managing coastal wetlands.

  2. Predictive occurrence models for coastal wetland plant communities: Delineating hydrologic response surfaces with multinomial logistic regression

    Science.gov (United States)

    Snedden, Gregg A.; Steyer, Gregory D.

    2013-02-01

    Understanding plant community zonation along estuarine stress gradients is critical for effective conservation and restoration of coastal wetland ecosystems. We related the presence of plant community types to estuarine hydrology at 173 sites across coastal Louisiana. Percent relative cover by species was assessed at each site near the end of the growing season in 2008, and hourly water level and salinity were recorded at each site Oct 2007-Sep 2008. Nine plant community types were delineated with k-means clustering, and indicator species were identified for each of the community types with indicator species analysis. An inverse relation between salinity and species diversity was observed. Canonical correspondence analysis (CCA) effectively segregated the sites across ordination space by community type, and indicated that salinity and tidal amplitude were both important drivers of vegetation composition. Multinomial logistic regression (MLR) and Akaike's Information Criterion (AIC) were used to predict the probability of occurrence of the nine vegetation communities as a function of salinity and tidal amplitude, and probability surfaces obtained from the MLR model corroborated the CCA results. The weighted kappa statistic, calculated from the confusion matrix of predicted versus actual community types, was 0.7 and indicated good agreement between observed community types and model predictions. Our results suggest that models based on a few key hydrologic variables can be valuable tools for predicting vegetation community development when restoring and managing coastal wetlands.

  3. Response of a Sphagnum bog plant community to elevated CO2 and N supply

    NARCIS (Netherlands)

    Heijmans, M.M.P.D.; Klees, H.; Visser, de W.; Berendse, F.

    2002-01-01

    The response of plant growth to rising CO2 levels appears to depend on nutrient availability, but it is not known whether the growth of bog plants reacts similarly. We therefore studied the effects of elevated CO2 in combination with N supply on the growth of Sphagnum mosses and vascular plants in

  4. Teasing apart plant community responses to N enrichment: the roles of resource limitation, competition and soil microbes.

    Science.gov (United States)

    Farrer, Emily C; Suding, Katharine N

    2016-10-01

    Although ecologists have documented the effects of nitrogen enrichment on productivity, diversity and species composition, we know little about the relative importance of the mechanisms driving these effects. We propose that distinct aspects of environmental change associated with N enrichment (resource limitation, asymmetric competition, and interactions with soil microbes) drive different aspects of plant response. We test this in greenhouse mesocosms, experimentally manipulating each factor across three ecosystems: tallgrass prairie, alpine tundra and desert grassland. We found that resource limitation controlled productivity responses to N enrichment in all systems. Asymmetric competition was responsible for diversity declines in two systems. Plant community composition was impacted by both asymmetric competition and altered soil microbes, with some contributions from resource limitation. Results suggest there may be generality in the mechanisms of plant community change with N enrichment. Understanding these links can help us better predict N response across a wide range of ecosystems. © 2016 John Wiley & Sons Ltd/CNRS.

  5. Forest Plant community changes during 1989-2007 in response to climate warming in the Jura Mountains (France and Switzerland)

    DEFF Research Database (Denmark)

    Lenoir, Jonathan; Gégout, J.C.; Dupouey, J.L.

    2010-01-01

    Question: How strong are climate warming-driven changes within mid-elevation forest communities? Observations of plant community change within temperate mountain forest ecosystems in response to recent warming are scarce in comparison to high-elevation alpine and nival ecosystems, perhaps...... reflecting the confounding influence of forest stand dynamics. Location: Jura Mountains (France and Switzerland). Methods: We assessed changes in plant community composition by surveying 154 Abies alba forest vegetation relevés (550-1,350 m a.s.l.) in 1989 and 2007. Over this period, temperatures increased...... while precipitation did not change. Correspondence analysis (CA) and ecological indicator values were used to measure changes in plant community composition. Relevés in even- and uneven-aged stands were analysed separately to determine the influence of forest stand dynamics. We also analysed changes...

  6. Fungal Communities in Rhizosphere Soil under Conservation Tillage Shift in Response to Plant Growth

    Directory of Open Access Journals (Sweden)

    Ziting Wang

    2017-07-01

    Full Text Available Conservation tillage is an extensively used agricultural practice in northern China that alters soil texture and nutrient conditions, causing changes in the soil microbial community. However, how conservation tillage affects rhizosphere and bulk soil fungal communities during plant growth remains unclear. The present study investigated the effect of long-term (6 years conservation (chisel plow, zero and conventional (plow tillage during wheat growth on the rhizosphere fungal community, using high-throughput sequencing of the internal transcribed spacer (ITS gene and quantitative PCR. During tillering, fungal alpha diversity in both rhizosphere and bulk soil were significantly higher under zero tillage compared to other methods. Although tillage had no significant effect during the flowering stage, fungal alpha diversity at this stage was significantly different between rhizosphere and bulk soils, with bulk soil presenting the highest diversity. This was also reflected in the phylogenetic structure of the communities, as rhizosphere soil communities underwent a greater shift from tillering to flowering compared to bulk soil communities. In general, less variation in community structure was observed under zero tillage compared to plow and chisel plow treatments. Changes in the relative abundance of the fungal orders Capnodiales, Pleosporales, and Xylariales contributed the highest to the dissimilarities observed. Structural equation models revealed that the soil fungal communities under the three tillage regimes were likely influenced by the changes in soil properties associated with plant growth. This study suggested that: (1 differences in nutrient resources between rhizosphere and bulk soils can select for different types of fungi thereby increasing community variation during plant growth; (2 tillage can alter fungal communities' variability, with zero tillage promoting more stable communities. This work suggests that long-term changes in

  7. Tracking fungal community responses to maize plants by DNA- and RNA-based pyrosequencing.

    Directory of Open Access Journals (Sweden)

    Eiko E Kuramae

    Full Text Available We assessed soil fungal diversity and community structure at two sampling times (t1 = 47 days and t2 = 104 days of plant age in pots associated with four maize cultivars, including two genetically modified (GM cultivars by high-throughput pyrosequencing of the 18S rRNA gene using DNA and RNA templates. We detected no significant differences in soil fungal diversity and community structure associated with different plant cultivars. However, DNA-based analyses yielded lower fungal OTU richness as compared to RNA-based analyses. Clear differences in fungal community structure were also observed in relation to sampling time and the nucleic acid pool targeted (DNA versus RNA. The most abundant soil fungi, as recovered by DNA-based methods, did not necessary represent the most "active" fungi (as recovered via RNA. Interestingly, RNA-derived community compositions at t1 were highly similar to DNA-derived communities at t2, based on presence/absence measures of OTUs. We recovered large proportions of fungal sequences belonging to arbuscular mycorrhizal fungi and Basidiomycota, especially at the RNA level, suggesting that these important and potentially beneficial fungi are not affected by the plant cultivars nor by GM traits (Bt toxin production. Our results suggest that even though DNA- and RNA-derived soil fungal communities can be very different at a given time, RNA composition may have a predictive power of fungal community development through time.

  8. Contrasting trait responses in plant communities to experimental and geographic variation in precipitation

    DEFF Research Database (Denmark)

    Sandel, Brody Steven; Goldstein, Leah; Kraft, Nathan

    2010-01-01

    Patterns of precipitation are likely to change significantly in the coming century, with important but poorly understood consequences for plant communities. Experimental and correlative studies may provide insight into expected changes, but little research has addressed the degree of concordance...... between these approaches. We synthesized results from four experimental water addition studies with a correlative analysis of community changes across a large natural precipitation gradient in the United States. We investigated whether community composition, summarized with plant functional traits......, responded similarly to increasing precipitation among studies and sites. In field experiments, increased precipitation favored species with small seed size,short leaf life span and high leaf nitrogen (N) concentration. However, with increasing precipitation along the natural gradient, community composition...

  9. MBS Native Plant Communities

    Data.gov (United States)

    Minnesota Department of Natural Resources — This data layer contains results of the Minnesota County Biological Survey (MCBS). It includes polygons representing the highest quality native plant communities...

  10. Dissimilar response of plant and soil biota communities to long-term nutrient adition in grasslands

    NARCIS (Netherlands)

    Wal, van der A.; Geerts, R.H.E.M.; Korevaar, H.; Schouten, A.J.; Jagers op Akkerhuis, G.A.J.M.; Rutgers, M.; Mulder, C.

    2009-01-01

    The long-term effect of fertilizers on plant diversity and productivity is well known, but long-term effects on soil biota communities have received relatively little attention. Here, we used an exceptional long-lasting (>40 years) grassland fertilization experiment to investigate the long-term

  11. Moving forward on facilitation research: response to changing environments and effects on the diversity, functioning and evolution of plant communities

    Science.gov (United States)

    Soliveres, Santiago; Smit, Christian; Maestre, Fernando T.

    2015-01-01

    Once seen as anomalous, facilitative interactions among plants and their importance for community structure and functioning are now widely recognized. The growing body of modelling, descriptive and experimental studies on facilitation covers a wide variety of terrestrial and aquatic systems throughout the globe. However, the lack of a general body of theory linking facilitation among different types of organisms and biomes and their responses to environmental changes prevents further advances in our knowledge regarding the evolutionary and ecological implications of facilitation in plant communities. Moreover, insights gathered from alternative lines of inquiry may substantially improve our understanding of facilitation, but these have been largely neglected thus far. Despite over 15 years of research and debate on this topic, there is no consensus on the degree to which plant–plant interactions change predictably along environmental gradients (i.e. the stress-gradient hypothesis), and this hinders our ability to predict how plant–plant interactions may affect the response of plant communities to ongoing global environmental change. The existing controversies regarding the response of plant–plant interactions across environmental gradients can be reconciled when clearly considering and determining the species-specificity of the response, the functional or individual stress type, and the scale of interest (pairwise interactions or community-level response). Here, we introduce a theoretical framework to do this, supported by multiple lines of empirical evidence. We also discuss current gaps in our knowledge regarding how plant–plant interactions change along environmental gradients. These include the existence of thresholds in the amount of species-specific stress that a benefactor can alleviate, the linearity or non-linearity of the response of pairwise interactions across distance from the ecological optimum of the beneficiary, and the need to explore

  12. Modeling dynamics of tundra plant communities on the Yamal Peninsula, Russia, in response to climate change and grazing pressure

    International Nuclear Information System (INIS)

    Yu, Q; Epstein, H E; Frost, G V; Walker, D A; Forbes, B C

    2011-01-01

    Understanding the responses of the arctic tundra biome to a changing climate requires knowledge of the complex interactions among the climate, soils and biological system. This study investigates the individual and interaction effects of climate change and reindeer grazing across a variety of climate zones and soil texture types on tundra vegetation community dynamics using an arctic vegetation model that incorporates the reindeer diet, where grazing is a function of both foliar nitrogen concentration and reindeer forage preference. We found that grazing is important, in addition to the latitudinal climate gradient, in controlling tundra plant community composition, explaining about 13% of the total variance in model simulations for all arctic tundra subzones. The decrease in biomass of lichen, deciduous shrub and graminoid plant functional types caused by grazing is potentially dampened by climate warming. Moss biomass had a nonlinear response to increased grazing intensity, and such responses were stronger when warming was present. Our results suggest that evergreen shrubs may benefit from increased grazing intensity due to their low palatability, yet a growth rate sensitivity analysis suggests that changes in nutrient uptake rates may result in different shrub responses to grazing pressure. Heavy grazing caused plant communities to shift from shrub tundra toward moss, graminoid-dominated tundra in subzones C and D when evergreen shrub growth rates were decreased in the model. The response of moss, lichen and forbs to warming varied across the different subzones. Initial vegetation responses to climate change during transient warming are different from the long term equilibrium responses due to shifts in the controlling mechanisms (nutrient limitation versus competition) within tundra plant communities.

  13. Is fire exclusion in mountain big sagebrush communities prudent? Soil nutrient, plant diversity, and arthropod response to burning

    Science.gov (United States)

    Fire has largely been excluded from many mountain big sagebrush (Artemisia tridentata Nutt. ssp. vaseyana (Rydb.) Beetle) communities. Land and wildlife managers are especially reluctant to reintroduce fire in mountain big sagebrush plant communities, especially those communities without significan...

  14. Mountain Plant Community Sentinels: AWOL

    Science.gov (United States)

    Malanson, G. P.

    2017-12-01

    Mountain plant communities are thought to be sensitive to climate change. Because climatic gradients are steep on mountain slopes, the spatial response of plant communities to climate change should be compressed and easier to detect. These expectations have led to identifying mountain plant communities as sentinels for climate change. This idea has, however, been criticized. Two critiques, for alpine treeline and alpine tundra, are rehearsed and supplemented. The critique of alpine treeline as sentinel is bolstered with new model results on the confounding role of dispersal mechanisms and sensitivity to climatic volatility. In alpine tundra, for which background turnover rates have yet to be established, community composition may reflect environmental gradients only for extremes where effects of climate are most indirect. Both plant communities, while primarily determined by energy at broad scales, may respond to water as a proximate driver at local scales. These plant communities may not be in equilibrium with climate, and differently scaled time lags may mean that ongoing vegetation change may not signal ongoing climate change (or lack thereof). In both cases a double-whammy is created by scale dependence for time lags and for drivers leading to confusion, but these cases present opportunities for insights into basic ecology.

  15. Modeled subalpine plant community response to climate change and atmospheric nitrogen deposition in Rocky Mountain National Park, USA

    International Nuclear Information System (INIS)

    McDonnell, T.C.; Belyazid, S.; Sullivan, T.J.; Sverdrup, H.; Bowman, W.D.; Porter, E.M.

    2014-01-01

    To evaluate potential long-term effects of climate change and atmospheric nitrogen (N) deposition on subalpine ecosystems, the coupled biogeochemical and vegetation community competition model ForSAFE-Veg was applied to a site at the Loch Vale watershed of Rocky Mountain National Park, Colorado. Changes in climate and N deposition since 1900 resulted in pronounced changes in simulated plant species cover as compared with ambient and estimated future community composition. The estimated critical load (CL) of N deposition to protect against an average future (2010–2100) change in biodiversity of 10% was between 1.9 and 3.5 kg N ha −1  yr −1 . Results suggest that the CL has been exceeded and vegetation at the study site has already undergone a change of more than 10% as a result of N deposition. Future increases in air temperature are forecast to cause further changes in plant community composition, exacerbating changes in response to N deposition alone. - Highlights: • A novel calibration step was introduced for modeling biodiversity with ForSAFE-Veg. • Modeled increases in tree cover are consistent with empirical studies. • Reductions in N deposition decreased future graminoid percent cover. • Critical loads of N to protect biodiversity should consider climate change effects. - Subalpine plant biodiversity in Rocky Mountain National Park has already been impacted by N deposition and climate change and is expected to experience significant future effects

  16. Soil microbial community structure and function responses to successive planting of Eucalyptus.

    Science.gov (United States)

    Chen, Falin; Zheng, Hua; Zhang, Kai; Ouyang, Zhiyun; Li, Huailin; Wu, Bing; Shi, Qian

    2013-10-01

    Many studies have shown soil degradation after the conversion of native forests to exotic Eucalyptus plantations. However, few studies have investigated the long-term impacts of short-rotation forestry practices on soil microorganisms. The impacts of Eucalyptus successive rotations on soil microbial communities were evaluated by comparing phospholipid fatty acid (PLFA) abundances, compositions, and enzyme activities of native Pinus massoniana plantations and adjacent 1st, 2nd, 3rd, 4th generation Eucalyptus plantations. The conversion from P. massoniana to Eucalyptus plantations significantly decreased soil microbial community size and enzyme activities, and increased microbial physiological stress. However, the PLFA abundances formed "u" shaped quadratic functions with Eucalyptus plantation age. Alternatively, physiological stress biomarkers, the ratios of monounsaturated to saturated fatty acid and Gram+ to Gram- bacteria, formed "n"' shaped quadratic functions, and the ratio of cy17:0 to 16:1omega7c decreased with plantation age. The activities of phenol oxidase, peroxidase, and acid phosphatase increased with Eucalyptus plantation age, while the cellobiohydrolase activity formed "u" shaped quadratic functions. Soil N:P, alkaline hydrolytic nitrogen, soil organic carbon, and understory cover largely explained the variation in PLFA profiles while soil N:P, alkaline hydrolytic nitrogen, and understory cover explained most of the variability in enzyme activity. In conclusion, soil microbial structure and function under Eucalyptus plantations were strongly impacted by plantation age. Most of the changes could be explained by altered soil resource availability and understory cover associated with successive planting of Eucalyptus. Our results highlight the importance of plantation age for assessing the impacts of plantation conversion as well as the importance of reducing disturbance for plantation management.

  17. Community attitudes toward nuclear plants

    International Nuclear Information System (INIS)

    Peelle, E.

    1982-01-01

    Among the many effects of the accident at Three Mile Island are impacts upon other communities that currently host nuclear-power reactors. Because studies on communities' reactions not immediately available, this chapter reviews existing studies and speculates about possible effects. The patterns and variations in impacts on and responses of nuclear host communities have been the subject of studies at Oak Ridge National Laboratory (Oak Ridge, Tennessee) since 1972. This essay presents results from four post-licensing studies of host communities - Plymouth, Massachusetts, and Waterford, Connecticut (PL-1), and Brunswick, North Carolina, and Appling-Toombs counties, Georgia (PL-2) - along with case study and attitude survey information from two additional communities in which reactors are under construction: Hartsville, Tennessee, and Cherokee County, South Carolina. Differences and similarities between the sites have been assessed in terms of differences in input and social structure; factors affecting the generally favorable attitudes toward local nuclear plants are discussed

  18. Responses of Ammonia-Oxidising Bacterial Communities to Nitrogen, Lime, and Plant Species in Upland Grassland Soil

    International Nuclear Information System (INIS)

    Rooney, D.C.; Kennedy, N.M.; Clipson, N.J.W.; Rooney, D.C.; Kennedy, N.M.; Gleeson, D.B.

    2010-01-01

    Agricultural improvement of semi natural grasslands has been shown to result in changes to plant and microbial diversity, with consequences for ecosystem functioning. A microcosm approach was used to elucidate the effects of two key components of agricultural improvement (nitrogen addition and liming) on ammonia-oxidising bacterial (AOB) communities in an upland grassland soil. Plant species characteristic of unimproved and improved pastures (A. capillaries and L. perenne) were planted in microcosms, and lime, nitrogen (NH 4 NO 3 ), or lime plus nitrogen added. The AOB community was profiled using terminal restriction fragment length polymorphism (TRFLP) of the amoA gene. AOB community structure was largely altered by NH 4 NO 3 addition, rather than liming, although interactions between nitrogen addition and plant species were also evident. Results indicate that nitrogen addition drives shifts in the structure of key microbial communities in upland grassland soils, and that plant species may play a significant role in determining AOB community structure

  19. Moving forward on facilitation research : Response to changing environments and effects on the diversity, functioning and evolution of plant communities

    NARCIS (Netherlands)

    Soliveres, Santiago; Smit, Christian; Maestre, Fernando T

    Once seen as anomalous, facilitative interactions among plants and their importance for community structure and functioning are now widely recognized. The growing body of modelling, descriptive and experimental studies on facilitation covers a wide variety of terrestrial and aquatic systems

  20. Responses of a constructed plant community to combinations of herbicides, a model for field tests?

    Science.gov (United States)

    As part of its regulation of pesticides, the US Environmental Protection Agency considers environmental risks, including impacts to nontarget plants exposed to pesticide drift. Normally these risk assessments consider impacts to individual species, using greenhouse, exposure-res...

  1. Response of herbaceous plant community diversity and composition to overstorey harvest within riparian management zones in Northern Hardwoods

    Science.gov (United States)

    Eric K. Zenner; Michelle A. Martin; Brian J. Palik; Jerilynn E. Peck; Charles R. Blinn

    2013-01-01

    Partial timber harvest within riparian management zones (RMZs) may permit active management of riparian forests while protecting stream ecosystems, but impacts on herbaceous communities are poorly understood. We compared herbaceous plant community abundance, diversity and composition in RMZs along small streams in northern Minnesota, USA, among four treatments before...

  2. Plants, birds and butterflies: short-term responses of species communities to climate warming vary by taxon and with altitude.

    Science.gov (United States)

    Roth, Tobias; Plattner, Matthias; Amrhein, Valentin

    2014-01-01

    As a consequence of climate warming, species usually shift their distribution towards higher latitudes or altitudes. Yet, it is unclear how different taxonomic groups may respond to climate warming over larger altitudinal ranges. Here, we used data from the national biodiversity monitoring program of Switzerland, collected over an altitudinal range of 2500 m. Within the short period of eight years (2003-2010), we found significant shifts in communities of vascular plants, butterflies and birds. At low altitudes, communities of all species groups changed towards warm-dwelling species, corresponding to an average uphill shift of 8 m, 38 m and 42 m in plant, butterfly and bird communities, respectively. However, rates of community changes decreased with altitude in plants and butterflies, while bird communities changed towards warm-dwelling species at all altitudes. We found no decrease in community variation with respect to temperature niches of species, suggesting that climate warming has not led to more homogenous communities. The different community changes depending on altitude could not be explained by different changes of air temperatures, since during the 16 years between 1995 and 2010, summer temperatures in Switzerland rose by about 0.07°C per year at all altitudes. We discuss that land-use changes or increased disturbances may have prevented alpine plant and butterfly communities from changing towards warm-dwelling species. However, the findings are also consistent with the hypothesis that unlike birds, many alpine plant species in a warming climate could find suitable habitats within just a few metres, due to the highly varied surface of alpine landscapes. Our results may thus support the idea that for plants and butterflies and on a short temporal scale, alpine landscapes are safer places than lowlands in a warming world.

  3. Responses of constructed plant community to combinations of herbicides, a model for field tests?

    Science.gov (United States)

    As part of its regulation of pesticides, the US Environmental Protection Agency must consider environmental risks, including impacts to non-target plants exposed to pesticide drift. Normally these risk assessments consider impacts to individual species, using greenhouse, dose-re...

  4. 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.

  5. Evolution of resistance to a multiple-herbivore community: genetic correlations, diffuse coevolution, and constraints on the plant's response to selection.

    Science.gov (United States)

    Wise, Michael J; Rausher, Mark D

    2013-06-01

    Although plants are generally attacked by a community of several species of herbivores, relatively little is known about the strength of natural selection for resistance in multiple-herbivore communities-particularly how the strength of selection differs among herbivores that feed on different plant organs or how strongly genetic correlations in resistance affect the evolutionary responses of the plant. Here, we report on a field study measuring natural selection for resistance in a diverse community of herbivores of Solanum carolinense. Using linear phenotypic-selection analyses, we found that directional selection acted to increase resistance to seven species. Selection was strongest to increase resistance to fruit feeders, followed by flower feeders, then leaf feeders. Selection favored a decrease in resistance to a stem borer. Bootstrapping analyses showed that the plant population contained significant genetic variation for each of 14 measured resistance traits and significant covariances in one-third of the pairwise combinations of resistance traits. These genetic covariances reduced the plant's overall predicted evolutionary response for resistance against the herbivore community by about 60%. Diffuse (co)evolution was widespread in this community, and the diffuse interactions had an overwhelmingly constraining (rather than facilitative) effect on the plant's evolution of resistance. © 2013 The Author(s). Evolution © 2013 The Society for the Study of Evolution.

  6. Functional traits drive plant community and ecosystem response to global change across arctic and alpine environments

    DEFF Research Database (Denmark)

    Chisholm, Chelsea Lee

    hierarchical Bayesian modelling. Here I found that competition is generally stronger in warmer climates, and that functional traits do not consistently predict growth across climate space. I also demonstrated that the inclusion of functional trait information as stabilizing niche differences in competition...... delayed in ice-rich areas. Finally, colleagues and I used an observational approach to assess changes in nutrient dynamics across replicated treeline transects in temperate regions around the globe, where we found consistent temperature-mediated changes in both ground-layer plant and soil nutrients across...

  7. Plant responses to multiple herbivory

    NARCIS (Netherlands)

    Li, Yehua

    2016-01-01

    This thesis explores whether aphid-infestation interferes with the plant response to chewing herbivores and whether this impacts performance and behaviour of individual chewing insect herbivores and their natural enemies, as well as the entire insect community. I investigated this using three

  8. THE EUROPEAN POSITION OF DUTCH PLANT COMMUNITIES

    Directory of Open Access Journals (Sweden)

    J.A.M. JANSSEN

    2007-04-01

    Full Text Available In this paper it is analyzed for which plant communities (alliances the Netherlands has an international responsibility. Data has been brought together on the range and distribution of alliances in Europe, the area of plant communities in the Netherlands and surrounding countries and the occurrence of endemic associations in the Netherlands. The analysis resulted in a list of 34 out of 93 alliances in the Netherlands which are important from an international point of view.

  9. Litter quality and its response to water level drawdown in boreal peatlands at plant species and community level

    Science.gov (United States)

    Straková, Petra; Anttila, Jani; Spetz, Peter; Kitunen, Veikko; Tapanila, Tarja; Laiho, Raija

    2010-05-01

    There is increasing evidence that changes in the species composition and structure of plant communities induced by global change will have much more impact on plant-mediated carbon cycling than any phenotypic responses. These impacts are largely mediated by shifts in litter quality. There are few documentations of these changes so far, due to the relatively long time scale required for their direct observation. Here, we examine the changes in litter inputs induced by persistent water-level drawdown in boreal peatland sites. Peatlands contain a major proportion of the terrestrial carbon pool, and it is thus important to be able to predict their behaviour and role in the global C cycle under different global change factors. We studied the effects of short-term (ca. 4 years) and long-term (ca. 40 years) persistent water level (WL) drawdown on the quantity and chemical quality of above-ground plant litter inputs at three sites: bog, oligotrophic fen and mesotrophic fen. The parameters used to characterize litter quality included various extractable substances, cellulose, holocellulose, composition of hemicellulose (neutral sugars, uronic acids), lignin, CuO oxidation phenolic products, and concentrations of C, nitrogen (N), phosphorus (P), potassium, magnesium, manganese and calcium. Four different groups of litter were clearly distinct based on their chemical quality: foliar litters, graminoids, mosses and woody litters. The pristine conditions were characterized by Sphagnum moss and graminoid litter. Following short-term WL drawdown, changes in the quality and quantity of litter inputs were small. Following long-term WL drawdown, total litter inputs dramatically increased, due to increased tree litter inputs, and the litter type composition greatly changed. These changes resulted in annual inputs of 1901-2010 kg•ha-1 C, 22-24 kg•ha-1 N, 1.5-2.2 kg•ha-1 P, 967-1235 kg•ha-1 lignin and lignin-like compounds and 254-300 kg•ha-1 water solubles after long-term WL

  10. Rhizosphere bacterial communities of dominant steppe plants shift in response to a gradient of simulated nitrogen deposition

    Directory of Open Access Journals (Sweden)

    An eYang

    2015-08-01

    Full Text Available We evaluated effects of 9-year simulation of simulated nitrogen (N deposition on microbial composition and diversity in the rhizosphere of two dominant temperate grassland species: grass Stipa krylovii and forb Artemisia frigida. Microbiomes in S. krylovii and A.frigida rhizosphere differed, but changed consistently along the N gradient. These changes were correlated to N-induced shifts to plant community. Hence, as plant biomass changed, so did bacterial rhizosphere communities, a result consistent with the role that N fertilizer has been shown to play in altering plant-microbial mutualisms. A total of 23 bacterial phyla were detected in the two rhizospheric soils by pyrosequencing, with Proteobacteria, Acidobacteria and Bacteroidetes dominating the sequences of all samples. Bacterioidetes and Proteobacteria tended to increase, while Acidobacteria declined with increase in N addition rates. TM7 increased >5-fold in the high N addition rates, especially in S. krylovii rhizosphere. Nitrogen addition also decreased diversity of OTUs (operational taxonomic units, Shannon and Chao1 indices of rhizospheric microbes regardless of plant species. These results suggest that there were both similar but also specific changes in microbial communities of temperate steppes due to N deposition.

  11. Isolated and Community Contexts Produce Distinct Responses by Host Plants to the Presence of Ant-Aphid Interaction: Plant Productivity and Seed Viability

    Science.gov (United States)

    Santiago, Graziele Silva; Zurlo, Luana Fonseca; Ribas, Carla Rodrigues; Carvalho, Rafaela Pereira; Alves, Guilherme Pereira; Carvalho, Mariana Comanucci Silva; Souza, Brígida

    2017-01-01

    Ant-aphid interactions may affect host plants in several ways, however, most studies measure only the amount of fruit and seed produced, and do not test seed viability. Therefore, the aim of this study was to assess the effects of the presence of ant-aphid interactions upon host plant productivity and seed viability in two different contexts: isolated and within an arthropod community. For this purpose we tested the hypothesis that in both isolated and community contexts, the presence of an ant-aphid interaction will have a positive effect on fruit and seed production, seed biomass and rate of seed germination, and a negative effect on abnormal seedling rates, in comparison to plants without ants. We performed a field mesocosm experiment containing five treatments: Ant-aphid, Aphid, Community, Ant-free community and Control. We counted fruits and seeds produced by each treatment, and conducted experiments for seed biomass and germinability. We found that in the community context the presence of an ant-aphid interaction negatively affected fruit and seed production. We think this may be because aphid attendance by tending-ants promotes aphid damage to the host plant, but without an affect on seed weight and viability. On the other hand, when isolated, the presence of an ant-aphid interaction positively affected fruit and seed production. These positive effects are related to the cleaning services offered to aphids by tending-ants, which prevent the development of saprophytic fungi on the surface of leaves, which would cause a decrease in photosynthetic rates. Our study is important because we evaluated some parameters of plant fitness that have not been addressed very well by other studies involving the effects of ant-aphid interactions mainly on plants with short life cycles. Lastly, our context dependent approach sheds new light on how ecological interactions can vary among different methods of crop management. PMID:28141849

  12. Isolated and Community Contexts Produce Distinct Responses by Host Plants to the Presence of Ant-Aphid Interaction: Plant Productivity and Seed Viability.

    Directory of Open Access Journals (Sweden)

    Ernesto Oliveira Canedo-Júnior

    Full Text Available Ant-aphid interactions may affect host plants in several ways, however, most studies measure only the amount of fruit and seed produced, and do not test seed viability. Therefore, the aim of this study was to assess the effects of the presence of ant-aphid interactions upon host plant productivity and seed viability in two different contexts: isolated and within an arthropod community. For this purpose we tested the hypothesis that in both isolated and community contexts, the presence of an ant-aphid interaction will have a positive effect on fruit and seed production, seed biomass and rate of seed germination, and a negative effect on abnormal seedling rates, in comparison to plants without ants. We performed a field mesocosm experiment containing five treatments: Ant-aphid, Aphid, Community, Ant-free community and Control. We counted fruits and seeds produced by each treatment, and conducted experiments for seed biomass and germinability. We found that in the community context the presence of an ant-aphid interaction negatively affected fruit and seed production. We think this may be because aphid attendance by tending-ants promotes aphid damage to the host plant, but without an affect on seed weight and viability. On the other hand, when isolated, the presence of an ant-aphid interaction positively affected fruit and seed production. These positive effects are related to the cleaning services offered to aphids by tending-ants, which prevent the development of saprophytic fungi on the surface of leaves, which would cause a decrease in photosynthetic rates. Our study is important because we evaluated some parameters of plant fitness that have not been addressed very well by other studies involving the effects of ant-aphid interactions mainly on plants with short life cycles. Lastly, our context dependent approach sheds new light on how ecological interactions can vary among different methods of crop management.

  13. Early response of ground layer plant communities to wildfire and harvesting disturbance in forested peatland ecosystems in northern Minnesota, USA

    Science.gov (United States)

    Erika R. Rowe; Anthony W. D' Amato; Brian J. Palik; John C. Almendinger

    2017-01-01

    A rare, stand-replacing fire in northern Minnesota, USA provided the opportunity to compare the effects of wildfire and timber harvesting in two peatland forest communities, nutrient-poor black spruce (Picea mariana) bogs (BSB) and nutrient-rich tamarack (Larix laricina) swamps (RTS). We found the response between the two...

  14. Responses of soil N-fixing bacteria communities to invasive plant species under different types of simulated acid deposition

    Science.gov (United States)

    Wang, Congyan; Zhou, Jiawei; Jiang, Kun; Liu, Jun; Du, Daolin

    2017-06-01

    Biological invasions have incurred serious threats to native ecosystems in China, and soil N-fixing bacteria communities (SNB) may play a vital role in the successful plant invasion. Meanwhile, anthropogenic acid deposition is increasing in China, which may modify or upgrade the effects that invasive plant species can cause on SNB. We analyzed the structure and diversity of SNB by means of new generation sequencing technology in soils with different simulated acid deposition (SAD), i.e., different SO4 2- to NO3 - ratios, and where the invasive ( Amaranthus retroflexus L.) and the native species ( Amaranthus tricolor L.) grew mixed or isolated for 3 months. A. retroflexus itself did not exert significant effects on the diversity and richness of SNB but did it under certain SO4 2- to NO3 - ratios. Compared to soils where the native species grew isolated, the soils where the invasive A. retroflexus grew isolated showed lower relative abundance of some SNB classes under certain SAD treatments. Some types of SAD can alter soil nutrient content which in turn could affect SNB diversity and abundance. Specifically, greater SO4 2- to NO3 - ratios tended to have more toxic effects on SNB likely due to the higher exchange capacity of hydroxyl groups (OH-) between SO4 2- and NO3 -. As a conclusion, it can be expected a change in the structure of SNB after A. retroflexus invasion under acid deposition rich in sulfuric acid. This change may create a plant soil feedback favoring future A. retroflexus invasions.

  15. Soil mineral composition matters: response of microbial communities to phenanthrene and plant litter addition in long-term matured artificial soils.

    Science.gov (United States)

    Babin, Doreen; Vogel, Cordula; Zühlke, Sebastian; Schloter, Michael; Pronk, Geertje Johanna; Heister, Katja; Spiteller, Michael; Kögel-Knabner, Ingrid; Smalla, Kornelia

    2014-01-01

    The fate of polycyclic aromatic hydrocarbons (PAHs) in soil is determined by a suite of biotic and abiotic factors, and disentangling their role in the complex soil interaction network remains challenging. Here, we investigate the influence of soil composition on the microbial community structure and its response to the spiked model PAH compound phenanthrene and plant litter. We used long-term matured artificial soils differing in type of clay mineral (illite, montmorillonite) and presence of charcoal or ferrihydrite. The soils received an identical soil microbial fraction and were incubated for more than two years with two sterile manure additions. The matured artificial soils and a natural soil were subjected to the following spiking treatments: (I) phenanthrene, (II) litter, (III) litter + phenanthrene, (IV) unspiked control. Total community DNA was extracted from soil sampled on the day of spiking, 7, 21, and 63 days after spiking. Bacterial 16S rRNA gene and fungal internal transcribed spacer amplicons were quantified by qPCR and subjected to denaturing gradient gel electrophoresis (DGGE). DGGE analysis revealed that the bacterial community composition, which was strongly shaped by clay minerals after more than two years of incubation, changed in response to spiked phenanthrene and added litter. DGGE and qPCR showed that soil composition significantly influenced the microbial response to spiking. While fungal communities responded only in presence of litter to phenanthrene spiking, the response of the bacterial communities to phenanthrene was less pronounced when litter was present. Interestingly, microbial communities in all artificial soils were more strongly affected by spiking than in the natural soil, which might indicate the importance of higher microbial diversity to compensate perturbations. This study showed the influence of soil composition on the microbiota and their response to phenanthrene and litter, which may increase our understanding of

  16. Saltmarsh plant responses to eutrophication.

    Science.gov (United States)

    Johnson, David Samuel; Warren, R Scott; Deegan, Linda A; Mozdzer, Thomas J

    2016-12-01

    In saltmarsh plant communities, bottom-up pressure from nutrient enrichment is predicted to increase productivity, alter community structure, decrease biodiversity, and alter ecosystem functioning. Previous work supporting these predictions has been based largely on short-term, plot-level (e.g., 1-300 m 2 ) studies, which may miss landscape-level phenomena that drive ecosystem-level responses. We implemented an ecosystem-scale, nine-year nutrient experiment to examine how saltmarsh plants respond to simulated conditions of coastal eutrophication. Our study differed from previous saltmarsh enrichment studies in that we applied realistic concentrations of nitrate (70-100 μM NO 3 - ), the most common form of coastal nutrient enrichment, via tidal water at the ecosystem scale (~60,000 m 2 creeksheds). Our enrichments added a total of 1,700 kg N·creek -1 ·yr -1 , which increased N loading 10-fold vs. reference creeks (low-marsh, 171 g N·m -2 ·yr -1 ; high-marsh, 19 g N·m -2 ·yr -1 ). Nutrients increased the shoot mass and height of low marsh, tall Spartina alterniflora; however, declines in stem density resulted in no consistent increase in aboveground biomass. High-marsh plants S. patens and stunted S. alterniflora did not respond consistently to enrichment. Nutrient enrichment did not shift community structure, contrary to the prediction of nutrient-driven dominance of S. alterniflora and Distichlis spicata over S. patens. Our mild responses may differ from the results of previous studies for a number of reasons. First, the limited response of the high marsh may be explained by loading rates orders of magnitude lower than previous work. Low loading rates in the high marsh reflect infrequent inundation, arguing that inundation patterns must be considered when predicting responses to estuarine eutrophication. Additionally, we applied nitrate instead of the typically used ammonium, which is energetically favored over nitrate for plant uptake. Thus, the

  17. Soil microbial abundance, activity and diversity response in two different altitude-adapted plant communities affected by wildfire in Sierra Nevada National Park (Granada, Spain)

    Science.gov (United States)

    Bárcenas-Moreno, Gema; Zavala, Lorena; Jordan, Antonio; Bååth, Erland; Mataix-Beneyto, Jorge

    2013-04-01

    Plant communities can play an important role in fire severity and post-fire ecosystem recovery due to their role as combustible and different plant-soil microorganisms interactions. Possible differences induced by plant and microorganisms response after fire could affect the general ecosystem short and long-term response and its sustainability. The main objective of this work was the evaluation of the effect of wildfire on soil microbial abundance, activity and diversity in two different plant communities associated to different altitudes in Sierra Nevada National Park (Granada, Spain). Samples were collected in two areas located on the Sierra Nevada Mountain between 1700 and 2000 m above sea level which were affected by a large wildfire in 2005. Two samplings were carried out 8 and 20 months after fire and samples were collected in both burned and unburned (control) zones in each plant community area. Area A is located at 1700m and it is formed by Quercus rotundifolia forest while area B is located at 2000 m altitude and is composed of alpine vegetation formed by creeping bearing shrubs. Microbial biomass measured by Fumigation-Extraction method followed the same trend in both areas showing slight and no significant differences between burned and unburned area during the study period while viable and cultivable bacteria abundance were markedly higher in fire affected samples than in the control ones in both samplings. Viable and cultivable filamentous fungi had different behavior depending of plant vegetation community studied showing no differences between burned and unburned area in area A while was significantly higher in burned samples than in the control ones in area B. Microbial activity monitoring with soil microbial respiration appears to had been affected immediately after fire since microbial respiration was lower in burned samples from area A than in unburned one only 8 months after fire and no significant differences were observed between burned and

  18. Changes in root-associated microbial communities are determined by species-specific plant growth responses to stress and disturbance

    Czech Academy of Sciences Publication Activity Database

    Bouasria, A.; Mustafa, T.; de Bello, Francesco; Zinger, L.; Lemperiere, G.; Geremia, R. A.; Choler, P.

    2012-01-01

    Roč. 52, Sep-Oct 2012 (2012), s. 59-66 ISSN 1164-5563 Institutional support: RVO:67985939 Keywords : ecosystem function * bacterial communities * grassland communities Subject RIV: EF - Botanics Impact factor: 1.838, year: 2012

  19. Responses of Plant Community Composition to Long-term Changes in Snow Depth at the Great Basin Desert - Sierra Nevada ecotone.

    Science.gov (United States)

    Loik, M. E.

    2015-12-01

    Snowfall is the dominant hydrologic input for many high-elevation ecosystems of the western United States. Many climate models envision changes in California's Sierra Nevada snow pack characteristics, which would severely impact the storage and release of water for one of the world's largest economies. Given the importance of snowfall for future carbon cycling in high elevation ecosystems, how will these changes affect seedling recruitment, plant mortality, and community composition? To address this question, experiments utilize snow fences to manipulate snow depth and melt timing at a desert-montane ecotone in eastern California, USA. Long-term April 1 snow pack depth averages 1344 mm (1928-2015) but is highly variable from year to year. Snow fences increased equilibrium drift snow depth by 100%. Long-term changes in snow depth and melt timing are associated with s shift from shurbs to graminoids where snow depth was increased for >50 years. Changes in snow have impacted growth for only three plant species. Moreover, annual growth ring increments of the conifers Pinus jeffreyi and Pi. contorta were not equally sensitive to snow depth. There were over 8000 seedlings of the shrubs Artemisia tridentata and Purshia tridentata found in 6300 m2 in summer 2009, following about 1400 mm of winter snow and spring rain. The frequency of seedlings of A. tridentata and P. tridentata were much lower on increased-depth plots compared to ambient-depth, and reduced-depth plots. Survival of the first year was lowest for A. tridentata. Survival of seedlings from the 2008 cohort was much higher for P. tridentata than A. tridentata during the 2011-2015 drought. Results indicate complex interactions between snow depth and plant community characteristics, and that responses of plants at this ecotone may not respond similarly to increases vs. decreases in snow depth. These changes portend altered carbon uptake in this region under future snowfall scenarios.

  20. Structural and functional responses of plant communities to climate change-mediated alterations in the hydrology of riparian areas in temperate Europe.

    Science.gov (United States)

    Baattrup-Pedersen, Annette; Garssen, Annemarie; Göthe, Emma; Hoffmann, Carl Christian; Oddershede, Andrea; Riis, Tenna; van Bodegom, Peter M; Larsen, Søren E; Soons, Merel

    2018-04-01

    The hydrology of riparian areas changes rapidly these years because of climate change-mediated alterations in precipitation patterns. In this study, we used a large-scale in situ experimental approach to explore effects of drought and flooding on plant taxonomic diversity and functional trait composition in riparian areas in temperate Europe. We found significant effects of flooding and drought in all study areas, the effects being most pronounced under flooded conditions. In near-stream areas, taxonomic diversity initially declined in response to both drought and flooding (although not significantly so in all years) and remained stable under drought conditions, whereas the decline continued under flooded conditions. For most traits, we found clear indications that the functional diversity also declined under flooded conditions, particularly in near-stream areas, indicating that fewer strategies succeeded under flooded conditions. Consistent changes in community mean trait values were also identified, but fewer than expected. This can have several, not mutually exclusive, explanations. First, different adaptive strategies may coexist in a community. Second, intraspecific variability was not considered for any of the traits. For example, many species can elongate shoots and petioles that enable them to survive shallow, prolonged flooding but such abilities will not be captured when applying mean trait values. Third, we only followed the communities for 3 years. Flooding excludes species intolerant of the altered hydrology, whereas the establishment of new species relies on time-dependent processes, for instance the dispersal and establishment of species within the areas. We expect that altered precipitation patterns will have profound consequences for riparian vegetation in temperate Europe. Riparian areas will experience loss of taxonomic and functional diversity and, over time, possibly also alterations in community trait responses that may have cascading effects

  1. Changes in bird community composition in response to growth changes in short-rotation woody crop planting

    International Nuclear Information System (INIS)

    Tolbert, V.R.; Hanowski, J.; Schiller, A.; Hoffman, W.; Christian, D.; Lindberg, J.

    1997-01-01

    Hybrid poplar established as intensively managed short-rotation woody crops (SRWC) on former agricultural lands can provide habitat for wildlife. Studies of bird use of SRWC for nesting and during fall migration have shown that the numbers and kinds of breeding birds using mature plantings of hybrid poplar are similar to natural forested lands. In Minnesota, the number of species of breeding birds using habitat provided by clonal-trial plantings and young larger-scale plantings (12-64 ha) of hybrid poplar were initially most similar to those using grasslands and row-crops. As the plantings approached canopy closure, successional species became predominant. In the Pacific Northwest, breeding bird composition and density were very similar for mature plantings and forested areas; however, fall migrants were found primarily in forested areas. In the Southeast, preliminary comparisons of breeding bird use of plantings of sweetgum and sycamore with naturally regenerating forests of different ages and sizes and vegetation structure are showing no size effect on use. As with hybrid poplar, species use of the more mature plantings of sweetgum and sycamore was most similar to that of natural forests. (author)

  2. Plant diversity and plant identity influence Fusarium communities in soil.

    Science.gov (United States)

    LeBlanc, Nicholas; Kinkel, Linda; Kistler, H Corby

    2017-01-01

    Fusarium communities play important functional roles in soil and in plants as pathogens, endophytes, and saprotrophs. This study tests how rhizosphere Fusarium communities may vary with plant species, changes in the diversity of the surrounding plant community, and soil physiochemical characteristics. Fusarium communities in soil associated with the roots of two perennial prairie plant species maintained as monocultures or growing within polyculture plant communities were characterized using targeted metagenomics. Amplicon libraries targeting the RPB2 locus were generated from rhizosphere soil DNAs and sequenced using pyrosequencing. Sequences were clustered into operational taxonomic units (OTUs) and assigned a taxonomy using the Evolutionary Placement Algorithm. Fusarium community composition was differentiated between monoculture and polyculture plant communities, and by plant species in monoculture, but not in polyculture. Taxonomic classification of the Fusarium OTUs showed a predominance of F. tricinctum and F. oxysporum as well of the presence of a clade previously only found in the Southern Hemisphere. Total Fusarium richness was not affected by changes in plant community richness or correlated with soil physiochemical characteristics. However, OTU richness within two predominant phylogenetic lineages within the genus was positively or negatively correlated with soil physiochemical characteristics among samples within each lineage. This work shows that plant species, plant community richness, and soil physiochemical characteristics may all influence the composition and richness of Fusarium communities in soil.

  3. Invasiveness does not predict impact: response of native land snail communities to plant invasions in riparian habitats

    Czech Academy of Sciences Publication Activity Database

    Horáčková, J.; Juřičková, L.; Šizling, A. L.; Jarošík, Vojtěch; Pyšek, Petr

    2014-01-01

    Roč. 9, č. 9 (2014), s. 1-10, e108296 E-ISSN 1932-6203 Institutional support: RVO:67985939 Keywords : plant invasions * land snails * impact Subject RIV: EF - Botanics Impact factor: 3.234, year: 2014

  4. Response of Vascular Plant Communities to Harvest in Southern Appalachian Mixed-Oak Forests: Two-Year Results

    Science.gov (United States)

    Bryan W. Wender; Sharon M. Hood; David W. Smith; Shepard M. Zedaker; David L. Loftis

    1999-01-01

    A long-term study has been established to monitor the effects of seven silvicultural prescriptions on vascular flora community attributes. Treatments include a control, understory vegetation control, group selection, two levels of shelterwoods, leave-tree, and clearcut. Second growing season. post-treatment results are compared to pre-harvest values for residual~...

  5. Integrating quantitative morphological and qualitative molecular methods to analyse soil nematode community responses to plant range expansion

    NARCIS (Netherlands)

    Geisen, S.; Snoek, B.; Ten Hooven, F.C.; Duyts, H.; Kostenko, O.; Bloem, Janneke; Martens, H.J.; Quist, C.W.; Helder, Johannes; van der Putten, W.H.

    2018-01-01

    Below‐ground nematodes are important for soil functioning, as they are ubiquitous and operate at various trophic levels in the soil food web. However, morphological nematode community analysis is time consuming and requires ample training. qPCR‐based nematode identification techniques are well

  6. Embracing community ecology in plant microbiome research

    NARCIS (Netherlands)

    Dini-Andreote, F.; Raaijmakers, J.M.

    2018-01-01

    Community assembly is mediated by selection, dispersal, drift, and speciation. Environmental selection is mostly used to date to explain patterns in plant microbiome assembly, whereas the influence of the other processes remains largely elusive. Recent studies highlight that adopting community

  7. Scaling environmental change through the community-level: a trait-based response-and-effect framework for plants.

    NARCIS (Netherlands)

    Suding, K.N.; Lavorel, S.; Chapin III, F.S.; Cornelissen, J.H.C.; Diaz, S.; Garnier, E.; Goldberg, D.; Hooper, D.U.; Jackson, S.T.; Navas, M.-L.

    2008-01-01

    Predicting ecosystem responses to global change is a major challenge in ecology. A critical step in that challenge is to understand how changing environmental conditions influence processes across levels of ecological organization. While direct scaling from individual to ecosystem dynamics can lead

  8. Scaling environmental change through the community level: a trait-based response-and-effect framework for plants

    Science.gov (United States)

    Katharine N. Suding; Sandra Lavorel; F. Stuart Chapin; Johannes H.C. Cornelissen; Sandra Diaz; Eric Garnier; Deborah Goldberg; David U. Hooper; Stephen T. Jackson; Marie-Laure. Navas

    2008-01-01

    Predicting ecosystem responses to global change is a major challenge in ecology. A critical step in that challenge is to understand how changing environmental conditions influence processes across levels of ecological organization. While direct scaling from individual to ecosystem dynamics can lead to robust and mechanistic predictions, new approaches are needed to...

  9. Interaction of historical and nonhistorical disturbances maintains native plant communities.

    Science.gov (United States)

    Davies, K W; Svejcar, T J; Bates, J D

    2009-09-01

    Historical disturbance regimes are often considered a critical element in maintaining native plant communities. However, the response of plant communities to disturbance may be fundamentally altered as a consequence of invasive plants, climate change, or prior disturbances. The appropriateness of historical disturbance patterns under modern conditions and the interactions among disturbances are issues that ecologists must address to protect and restore native plant communities. We evaluated the response of Artemisia tridentata ssp. wyomingensis (Beetle & A. Young) S.L. Welsh plant communities to their historical disturbance regime compared to other disturbance regimes. The historical disturbance regime of these plant communities was periodic fires with minimal grazing by large herbivores. We also investigated the influence of prior disturbance (grazing) on the response of these communities to subsequent disturbance (burning). Treatments were: (1) ungrazed (livestock grazing excluded since 1936) and unburned, (2) grazed and unburned, (3) ungrazed and burned (burned in 1993), and (4) grazed and burned. The ungrazed-burned treatment emulated the historical disturbance regime. Vegetation cover, density, and biomass production were measured the 12th, 13th, and 14th year post-burning. Prior to burning the presence of Bromus tectorum L., an exotic annual grass, was minimal (resilience to more severe disturbances. Modern deviations from historical conditions can alter ecosystem response to disturbances, thus restoring the historical disturbance regime may not be an appropriate strategy for all ecosystems.

  10. Catastrophic flood disturbance and a community's response to plant resilience in the heart of the Texas Hill Country

    Science.gov (United States)

    Meitzen, Kimberly M.; Phillips, John N.; Perkins, Thaïs; Manning, Aspen; Julian, Jason P.

    2018-03-01

    The Blanco River, which flows through the limestone Balcones Canyonlands of central Texas (USA), experienced catastrophic flooding in May 2015 that resulted in significant biogeomorphic disturbance to its riparian corridor. High-resolution aerial and satellite imagery from pre- and post-flooding for a 55-km reach of river were used to map and categorize patterns of disturbance by degree of severity ranging from complete floodplain stripping to no disturbance. The most severe disturbance occurred within the floodway near the channel and decreased with lateral distance into the 100- and 500-year floodplains. Disturbance patterns previously identified in the literature including meander scour, parallel chute scour, convex bank erosion, and macroturbulent scour were all present following this event, as well as substantial disturbance proximal to tributary confluences. In the aftermath of this event, TreeFolks, a local nonprofit organization, engaged with the community to actively replant and restore the riparian corridor of the Blanco River on public and private lands. These reforestation efforts supplement the natural passive recovery of the riparian corridor, enabling the system to recover more quickly and be resilient to future flood events.

  11. Plant succession and approaches to community restoration

    Science.gov (United States)

    Bruce A. Roundy

    2005-01-01

    The processes of vegetation change over time, or plant succession, are also the processes involved in plant community restoration. Restoration efforts attempt to use designed disturbance, seedbed preparation and sowing methods, and selection of adapted and compatible native plant materials to enhance ecological function. The large scale of wildfires and weed invasion...

  12. Plant response to butterfly eggs

    NARCIS (Netherlands)

    Griese, Eddie; Dicke, Marcel; Hilker, Monika; Fatouros, Nina E.

    2017-01-01

    Plants employ various defences killing the insect attacker in an early stage. Oviposition by cabbage white butterflies (Pieris spp.) on brassicaceous plants, including Brassica nigra, induces a hypersensitive response (HR) - like leaf necrosis promoting desiccation of eggs. To gain a deeper insight

  13. Modelling asymmetric growth in crowded plant communities

    DEFF Research Database (Denmark)

    Damgaard, Christian

    2010-01-01

    A class of models that may be used to quantify the effect of size-asymmetric competition in crowded plant communities by estimating a community specific degree of size-asymmetric growth for each species in the community is suggested. The model consists of two parts: an individual size......-asymmetric growth part, where growth is assumed to be proportional to a power function of the size of the individual, and a term that reduces the relative growth rate as a decreasing function of the individual plant size and the competitive interactions from other plants in the neighbourhood....

  14. Plant Responses to Nanoparticle Stress

    Directory of Open Access Journals (Sweden)

    Zahed Hossain

    2015-11-01

    Full Text Available With the rapid advancement in nanotechnology, release of nanoscale materials into the environment is inevitable. Such contamination may negatively influence the functioning of the ecosystems. Many manufactured nanoparticles (NPs contain heavy metals, which can cause soil and water contamination. Proteomic techniques have contributed substantially in understanding the molecular mechanisms of plant responses against various stresses by providing a link between gene expression and cell metabolism. As the coding regions of genome are responsible for plant adaptation to adverse conditions, protein signatures provide insights into the phytotoxicity of NPs at proteome level. This review summarizes the recent contributions of plant proteomic research to elaborate the complex molecular pathways of plant response to NPs stress.

  15. Responses of plants to air pollution

    National Research Council Canada - National Science Library

    Mudd, J. Brian; Kozlowski, T. T

    1975-01-01

    .... KOZLOWSKI Pollution, 1975 ELROY L. RICE. Allelopathy, (Eds.). Fire and Ecosystems, 1974 (Eds.). Responses of Plants to Air Responses of Plants to Air PollutionRESPONSES OF PLANTS TO AIR POLLUTION E...

  16. Microbial Community Dynamics and Response to Plant Growth-Promoting Microorganisms in the Rhizosphere of Four Common Food Crops Cultivated in Hydroponics.

    Science.gov (United States)

    Sheridan, C; Depuydt, P; De Ro, M; Petit, C; Van Gysegem, E; Delaere, P; Dixon, M; Stasiak, M; Aciksöz, S B; Frossard, E; Paradiso, R; De Pascale, S; Ventorino, V; De Meyer, T; Sas, B; Geelen, D

    2017-02-01

    Plant growth promoting microorganisms (PGPMs) of the plant root zone microbiome have received limited attention in hydroponic cultivation systems. In the framework of a project aimed at the development of a biological life support system for manned missions in space, we investigated the effects of PGPMs on four common food crops (durum and bread wheat, potato and soybean) cultivated in recirculating hydroponic systems for a whole life cycle. Each crop was inoculated with a commercial PGPM mixture and the composition of the microbial communities associated with their root rhizosphere, rhizoplane/endosphere and with the recirculating nutrient solution was characterised through 16S- and ITS-targeted Illumina MiSeq sequencing. PGPM addition was shown to induce changes in the composition of these communities, though these changes varied both between crops and over time. Microbial communities of PGPM-treated plants were shown to be more stable over time. Though additional development is required, this study highlights the potential benefits that PGPMs may confer to plants grown in hydroponic systems, particularly when cultivated in extreme environments such as space.

  17. Soil bacterial community responses to global changes

    DEFF Research Database (Denmark)

    Bergmark, Lasse

    competing and very contrasting plant types (Calluna and Deschampsia) dominated the vegetation. This led to Manuscript 3 where the impact and responses of the climate change manipulations on the microbial community composition was investigated under the contrasting vegetation types. Our results show a high......Soil bacteria and archaea are essential for ecosystem functioning and plant growth through their degradation of organic matter and turnover of nutrients. But since the majority of soil bacteria and archaea are unclassified and “nonculturable” the functionality of the microbial community and its...... overall importance for ecosystem function in soil is poorly understood. Global change factors may affect the diversity and functioning of soil prokaryotes and thereby ecosystem functioning. To gain a better understanding of the effects of global changes it is of fundamental importance to classify...

  18. Community patterns of tropical tree phenology derived from Unmanned Aerial Vehicle images: intra- and interspecific variation, association with species plant traits, and response to interannual climate variation

    Science.gov (United States)

    Bohlman, Stephanie; Rifai, Sami; Park, John; Dandois, Jonathan; Muller-Landau, Helene

    2017-04-01

    identities of 2000 crowns in the images by linking the crowns to stem tags in the field, thus producing a time series of cumulative annual deciduousness for 65 species. Deciduousness showed continuous variation among species rather than distinct phenological categories (ie evergreen and deciduous) that are commonly used in physiological, ecosystem and modeling studies. Some species labelled as evergreen by expert-based classification had annual deciduousness higher than those labelled as deciduous. We found significant, positive relationships between species mean deciduousness and species' leaf phosphorous, photosynthetic capacity and adult relative growth rate, suggesting that higher deciduousness is associated with greater resource acquisition. Comparing May 2015 (during an El Nino drought) and May 2014 (an non El Nino year with normal rainfall), mean deciduousness values for nearly all species was greater in 2015 but with differing levels of intraspecific variation. We discuss how the variation in deciduousness among species, its relationship with plant traits and response to the drought might be incorporated into terrestrial biosphere models of tropical forests to more accurately represent phenology and understand the consequences of community-level variation in phenology for ecosystem processes.

  19. Field response of aboveground non-target arthropod community to transgenic Bt-Cry1Ab rice plant residues in postharvest seasons.

    Science.gov (United States)

    Bai, Yao-Yu; Yan, Rui-Hong; Ye, Gong-Yin; Huang, Fangneng; Wangila, David S; Wang, Jin-Jun; Cheng, Jia-An

    2012-10-01

    Risk assessments of ecological effects of transgenic rice expressing lepidoptera-Cry proteins from Bacillus thuringiensis (Bt) on non-target arthropods have primarily focused on rice plants during cropping season, whereas few studies have investigated the effects in postharvest periods. Harvested rice fallow fields provide a critical over-wintering habitat for arthropods in the Chinese rice ecosystems, particularly in the southern region of the country. During 2006-08, two independent field trials were conducted in Chongqing, China to investigate the effects of transgenic Cry1Ab rice residues on non-target arthropod communities. In each trial, pitfall traps were used to sample arthropods in field plots planted with one non-Bt variety and two Bt rice lines expressing the Cry1Ab protein. Aboveground arthropods in the trial plots during the postharvest season were abundant, while community densities varied significantly between the two trials. A total of 52,386 individual insects and spiders, representing 93 families, was captured in the two trials. Predominant arthropods sampled were detritivores, which accounted for 91.9% of the total captures. Other arthropods sampled included predators (4.2%), herbivores (3.2%), and parasitoids (0.7%). In general, there were no significant differences among non-Bt and Bt rice plots in all arthropod community-specific parameters for both trials, suggesting no adverse impact of the Bt rice plant residues on the aboveground non-target arthropod communities during the postharvest season. The results of this study provide additional evidence that Bt rice is safe to non-target arthropod communities in the Chinese rice ecosystems.

  20. Seed bank characteristics of Dutch plant communities

    NARCIS (Netherlands)

    Bekker, RM; Schaminee, JHJ; Bakker, JP; Thompson, K

    With the recent appearances of a new and well-documented classification of the Dutch plant communities (Schaminee et al 1995a,b; 1996) and a database on the seed longevity of plant species of North West Europe (Thompson ct al. 1997a) it was possible to investigate patterns of seed longevity in Dutch

  1. Ozone sensitivity of plants in natural communities

    Energy Technology Data Exchange (ETDEWEB)

    Treshow, M; Stewart, D

    1973-07-01

    Field fumigation studies conducted in grassland, oak, aspen, and conifer, communities established the injury threshold of prevalent plant species to ozone. Several important species, including Bromus tectorum, Quercus gambelii, and Populus tremuloides, were injured by a single 2-hours exposure to 15 pphM ozone. Over half the perennial forbs and woody species studied were visibly injured at concentrations of 30 pphM ozone or less. It is postulated that lower concentrations at prolonged or repeated exposures to ozone may impair growth and affect community vigor and stability. Continued exposure of natural plant communities to ozone is expected to initiate major shifts in the plant composition of communities. 10 references, 4 figures, 1 table.

  2. Plant-plant competition outcomes are modulated by plant effects on the soil bacterial community.

    Science.gov (United States)

    Hortal, S; Lozano, Y M; Bastida, F; Armas, C; Moreno, J L; Garcia, C; Pugnaire, F I

    2017-12-19

    Competition is a key process that determines plant community structure and dynamics, often mediated by nutrients and water availability. However, the role of soil microorganisms on plant competition, and the links between above- and belowground processes, are not well understood. Here we show that the effects of interspecific plant competition on plant performance are mediated by feedbacks between plants and soil bacterial communities. Each plant species selects a singular community of soil microorganisms in its rhizosphere with a specific species composition, abundance and activity. When two plant species interact, the resulting soil bacterial community matches that of the most competitive plant species, suggesting strong competitive interactions between soil bacterial communities as well. We propose a novel mechanism by which changes in belowground bacterial communities promoted by the most competitive plant species influence plant performance and competition outcome. These findings emphasise the strong links between plant and soil communities, paving the way to a better understanding of plant community dynamics and the effects of soil bacterial communities on ecosystem functioning and services.

  3. Plant responses to metal toxicity

    Energy Technology Data Exchange (ETDEWEB)

    Briat, J.F. [Montpellier-2 Univ., 34 (France). Biochimie et physiologie moleculaire des plantes, CNRS, URA 2133; Lebrun, M. [Montpellier-2 Univ., 34 (France). Biochimie et physiologie vegetale appliquee

    1999-01-01

    Increased metal concentration in the soils, up to toxic levels, is becoming an important environmental problem. Safety rule evolution will require solutions in order to cope with food safety rules, and to freeze metal leakage from heavily metal-poisoned soils, such as those from industrial fallows. In this context, plants could serve to develop bio-assays in order to promote new standards, more realistic than the mass of a given metal per kg of soil, that does not consider the metal bio-disponibility. Plants could also be used for phyto-extraction and/or phyto-stabilization. To reach these objectives, a genetic approach could be useful to generate metal-tolerant plants with enough biomass. In this work is more particularly studied the plant responses to metal toxicity. Metal toxicity for living organisms involves oxidative and /or genotoxic mechanisms. Plant protection against metal toxicity occurs, at least in part, through control of root metal uptake and of long distance metal transport. Inside cells, proteins such as ferritins and metallothioneins, and glutathione-derived peptides named phyto-chelatins, participate in excess metal storage and detoxification. Low molecular weight organic molecules, mainly organic acids and amino acids and their derivatives, also play an important role in plant metal homeostasis. When these systems are overloaded, oxidative stress defense mechanisms are activated. Molecular and cellular knowledge of these processes will be necessary to improve plant metal resistance. Occurrence of naturally tolerant plants which hyper accumulate metals provides helpful tools for this research. (authors) 130 refs.

  4. PLANT COMMUNITIES OF ALBANIA - A PRELIMINARY OVERVIEW

    Directory of Open Access Journals (Sweden)

    J. DRING

    2002-04-01

    Full Text Available The phytosociological analysis of Albania was initiated by F. Markgraf in the 30ies, but still remains incomplete. This is a preliminary list of the plant communities resulting from the literature and from field research carried out during the last years and may represent a first contribution for further research. Many communities are described only by dominant species, other are quoted as nomina nuda. Some further syntaxa. probably present in the study area, are added.

  5. Plant responses to water stress

    Science.gov (United States)

    Kar, Rup Kumar

    2011-01-01

    Terrestrial plants most often encounter drought stress because of erratic rainfall which has become compounded due to present climatic changes.Responses of plants to water stress may be assigned as either injurious change or tolerance index. One of the primary and cardinal changes in response to drought stress is the generation of reactive oxygen species (ROS), which is being considered as the cause of cellular damage. However, recently a signaling role of such ROS in triggering the ROS scavenging system that may confer protection or tolerance against stress is emerging. Such scavenging system consists of antioxidant enzymes like SOD, catalase and peroxidases, and antioxidant compounds like ascorbate, reduced glutathione; a balance between ROS generation and scavenging ultimately determines the oxidative load. As revealed in case of defence against pathogen, signaling via ROS is initiated by NADPH oxidase-catalyzed superoxide generation in the apoplastic space (cell wall) followed by conversion to hydrogen peroxide by the activity of cell wall-localized SOD. Wall peroxidase may also play role in ROS generation for signaling. Hydrogen peroxide may use Ca2+ and MAPK pathway as downstream signaling cascade. Plant hormones associated with stress responses like ABA and ethylene play their role possibly via a cross talk with ROS towards stress tolerance, thus projecting a dual role of ROS under drought stress. PMID:22057331

  6. Response of aboveground carbon balance to long-term, experimental shifts in precipitation seasonality is contingent on plant community type in cold-desert rangelands

    Science.gov (United States)

    Reinhardt, K.; McAbee, K.; Germino, M. J.; Bosworth, A.

    2016-12-01

    Semi-arid rangelands have been identified as potential carbon (C) sinks. However, the degree of net C storage or release in water-limited systems is a function of precipitation amount and timing, as well as plant community composition. In northern latitudes of western North America, climate models predict increases in wintertime precipitation and decreases in summertime precipitation. In theory, this should boost C storage in cold-desert ecosystems that have deep-rooted woody plants due to greater wintertime soil water storage that enhances summertime productivity. However, there are few long-term, manipulative field-based studies investigating how shrub- and grass-dominated rangelands will respond to changing precipitation patterns. We measured aboveground C pools and fluxes at leaf, soil, and ecosystem scales over the 2014 growing season on plots that had supplemental precipitation added in either winter or summer for 21 years, in shrub- and exotic-bunchgrass-dominated plots. We hypothesized that increased winter precipitation would stimulate aboveground C uptake and storage relative to ambient conditions, in our cold-desert-adapted plant species. We further hypothesized that long-term gains in aboveground C storage due to precipitation manipulations would be greater in plots containing shrubs. Our hypotheses were generally supported: ecosystem C uptake and long-term biomass accumulation were greater in winter- and summer-irrigated plots compared to control plots in both vegetation communities. However, substantial increases in aboveground biomass occurred only in winter-irrigated plots that contained shrubs. Our findings suggest that increases in winter precipitation will enhance C storage of this widespread ecosystem, provided that the ecosystems have resisted conversion to exotic grassland.

  7. Nuclear power plant and the host community

    Energy Technology Data Exchange (ETDEWEB)

    Olsson, G

    1978-10-27

    A councillor from a small Swedish community (Kaevlinge) in the vicinity of the Barsebaeck nuclear power plant describes the effects which the plant has had on neighbouring communities. The effect on the labour market has been small at Kaevlinge, both during routine operation and construction phases. This is however, a fairly densely populated area with a population of half a million in a radius of 30 km. The situation is different at Oskarshamn or Oesthammar. Neither has there been any special economic benefit, due to Swedish taxation laws. There has been little local anxiety due to the proximity of the nuclear power plant. Certain local planning problems have been caused by restricted zones and power cables. Cooperation between the local authorities and the utility has been good.

  8. Licensee responsibility for nuclear power plant safety

    International Nuclear Information System (INIS)

    Schneider, Horst

    2010-01-01

    Simple sentences easy to grasp are desirable in regulations and bans. However, in a legal system, their meaning must be unambiguous. Article 6, Paragraph 1 of the EURATOM Directive on a community framework for the nuclear safety of nuclear facilities of June 2009 states that 'responsibility for the nuclear safety of a nuclear facility is incumbent primarily on the licensee.' The draft 'Safety Criteria for Nuclear Power Plants, Revision D, April 2009' of the German Federal Ministry for the Environment, Nature Conservation, and Nuclear Safety (BMU) (A Module 1, 'Safety Criteria for Nuclear Power Plants: Basic Safety Criteria' / '0 Principles' Paragraph 2) reads: 'Responsibility for ensuring safety rests with the licensee. He shall give priority to compliance with the safety goal over the achievement of other operational objectives.' In addition, the existing rules and regulations, whose rank is equivalent to that of international regulations, assign priority to the safety goal to be pursued by the licensee over all other objectives of the company. The operator's responsibility for nuclear safety can be required and achieved only on the basis of permits granted, which must meet legal requirements. The operator's proximity to plant operation is the reason for his 'primary responsibility.' Consequently, verbatim incorporation of Article 6, Paragraph 1 of the EURATOM Directive would only be a superscript added to existing obligations of the operator - inclusive of a safety culture designed as an incentive to further 'the spirit of safety-related actions' - without any new legal contents and consequences. In the reasons of the regulation, this would have to be clarified in addition to the cryptic wording of 'responsibility.. primarily,' at the same time expressing that operators and authorities work together in a spirit of openness and trust. (orig.)

  9. Plant interactions with multiple insect herbivores: from community to genes

    NARCIS (Netherlands)

    Stam, J.M.; Kroes, A.; Li, Y.; Gols, R.; Loon, van J.J.A.; Poelman, E.H.; Dicke, M.

    2014-01-01

    Every plant is a member of a complex insect community that consists of tens to hundreds of species that belong to different trophic levels. The dynamics of this community are critically influenced by the plant, which mediates interactions between community members that can occur on the plant

  10. Changes in plant species richness induce functional shifts in soil nematode communities in experimental grassland.

    Directory of Open Access Journals (Sweden)

    Nico Eisenhauer

    Full Text Available Changes in plant diversity may induce distinct changes in soil food web structure and accompanying soil feedbacks to plants. However, knowledge of the long-term consequences of plant community simplification for soil animal food webs and functioning is scarce. Nematodes, the most abundant and diverse soil Metazoa, represent the complexity of soil food webs as they comprise all major trophic groups and allow calculation of a number of functional indices.We studied the functional composition of nematode communities three and five years after establishment of a grassland plant diversity experiment (Jena Experiment. In response to plant community simplification common nematode species disappeared and pronounced functional shifts in community structure occurred. The relevance of the fungal energy channel was higher in spring 2007 than in autumn 2005, particularly in species-rich plant assemblages. This resulted in a significant positive relationship between plant species richness and the ratio of fungal-to-bacterial feeders. Moreover, the density of predators increased significantly with plant diversity after five years, pointing to increased soil food web complexity in species-rich plant assemblages. Remarkably, in complex plant communities the nematode community shifted in favour of microbivores and predators, thereby reducing the relative abundance of plant feeders after five years.The results suggest that species-poor plant assemblages may suffer from nematode communities detrimental to plants, whereas species-rich plant assemblages support a higher proportion of microbivorous nematodes stimulating nutrient cycling and hence plant performance; i.e. effects of nematodes on plants may switch from negative to positive. Overall, food web complexity is likely to decrease in response to plant community simplification and results of this study suggest that this results mainly from the loss of common species which likely alter plant-nematode interactions.

  11. Restructuring of endophytic bacterial communities in grapevine yellows-diseased and recovered Vitis vinifera L. plants.

    Science.gov (United States)

    Bulgari, Daniela; Casati, Paola; Crepaldi, Paola; Daffonchio, Daniele; Quaglino, Fabio; Brusetti, Lorenzo; Bianco, Piero Attilio

    2011-07-01

    Length heterogeneity-PCR assays, combined with statistical analyses, highlighted that the endophytic bacterial community associated with healthy grapevines was characterized by a greater diversity than that present in diseased and recovered plants. The findings suggest that phytoplasmas can restructure the bacterial community by selecting endophytic strains that could elicit a plant defense response.

  12. Gender Responsive Community Based Planning and Budgeting ...

    International Development Research Centre (IDRC) Digital Library (Canada)

    ... Responsive Community Based Planning and Budgeting Tool for Local Governance ... in data collection, and another module that facilitates gender responsive and ... In partnership with UNESCO's Organization for Women in Science for the ...

  13. 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

  14. Corporate Social Responsibility Agreements Model for Community ...

    African Journals Online (AJOL)

    Corporate Social Responsibility Agreements Model for Community ... their host communities with concomitant adverse effect on mining operations. ... sustainable community development an integral part of the mining business. This paper presents the evolutionary strategic models, with differing principles and action plans, ...

  15. Modeling wetland plant community response to assess water-level regulation scenarios in the Lake Ontario-St. Lawrence River basin

    Science.gov (United States)

    Hudon, Christiane; Wilcox, Douglas; Ingram, Joel

    2006-01-01

    The International Joint Commission has recently completed a five-year study (2000-2005) to review the operation of structures controlling the flows and levels of the Lake Ontario - St. Lawrence River system. In addition to addressing the multitude of stakeholder interests, the regulation plan review also considers environmental sustainability and integrity of wetlands and various ecosystem components. The present paper outlines the general approach, scientific methodology and applied management considerations of studies quantifying the relationships between hydrology and wetland plant assemblages (% occurrence, surface area) in Lake Ontario and the Upper and Lower St. Lawrence River. Although similar study designs were used across the study region, different methodologies were required that were specifically adapted to suit the important regional differences between the lake and river systems, range in water-level variations, and confounding factors (geomorphic types, exposure, sediment characteristics, downstream gradient of water quality, origin of water masses in the Lower River). Performance indicators (metrics), such as total area of wetland in meadow marsh vegetation type, that link wetland response to water levels will be used to assess the effects of different regulation plans under current and future (climate change) water-supply scenarios.

  16. Differential responses of soil bacteria, fungi, archaea and protists to plant species richness and plant functional group identity.

    Science.gov (United States)

    Dassen, Sigrid; Cortois, Roeland; Martens, Henk; de Hollander, Mattias; Kowalchuk, George A; van der Putten, Wim H; De Deyn, Gerlinde B

    2017-08-01

    Plants are known to influence belowground microbial community structure along their roots, but the impacts of plant species richness and plant functional group (FG) identity on microbial communities in the bulk soil are still not well understood. Here, we used 454-pyrosequencing to analyse the soil microbial community composition in a long-term biodiversity experiment at Jena, Germany. We examined responses of bacteria, fungi, archaea, and protists to plant species richness (communities varying from 1 to 60 sown species) and plant FG identity (grasses, legumes, small herbs, tall herbs) in bulk soil. We hypothesized that plant species richness and FG identity would alter microbial community composition and have a positive impact on microbial species richness. Plant species richness had a marginal positive effect on the richness of fungi, but we observed no such effect on bacteria, archaea and protists. Plant species richness also did not have a large impact on microbial community composition. Rather, abiotic soil properties partially explained the community composition of bacteria, fungi, arbuscular mycorrhizal fungi (AMF), archaea and protists. Plant FG richness did not impact microbial community composition; however, plant FG identity was more effective. Bacterial richness was highest in legume plots and lowest in small herb plots, and AMF and archaeal community composition in legume plant communities was distinct from that in communities composed of other plant FGs. We conclude that soil microbial community composition in bulk soil is influenced more by changes in plant FG composition and abiotic soil properties, than by changes in plant species richness per se. © 2017 The Authors. Molecular Ecology Published by John Wiley & Sons Ltd.

  17. The effects of glyphosate and aminopyralid on an artifical plant communities

    Science.gov (United States)

    The US EPA has responsibility for registration of pesticides under the Federal Insecticide, Fungicide, and Rodenticide Act (FIFRA). The potential adverse effects of pesticides to nontarget terrestrial plant communities are a concern that must be addressed in the pesticide regist...

  18. Plants having modified response to ethylene

    Science.gov (United States)

    Meyerowitz, E.M.; Chang, C.; Bleecker, A.B.

    1997-11-18

    The invention includes transformed plants having at least one cell transformed with a modified ETR nucleic acid. Such plants have a phenotype characterized by a decrease in the response of at least one transformed plant cell to ethylene as compared to a plant not containing the transformed plant cell. Tissue and/or temporal specificity for expression of the modified ETR nucleic acid is controlled by selecting appropriate expression regulation sequences to target the location and/or time of expression of the transformed nucleic acid. The plants are made by transforming at least one plant cell with an appropriate modified ETR nucleic acid, regenerating plants from one or more of the transformed plant cells and selecting at least one plant having the desired phenotype. 31 figs.

  19. Plant responses to insect egg deposition

    NARCIS (Netherlands)

    Hilker, M.; Fatouros, N.E.

    2015-01-01

    Plants can respond to insect egg deposition and thus resist attack by herbivorous insects from the beginning of the attack, egg deposition. We review ecological effects of plant responses to insect eggs and differentiate between egg-induced plant defenses that directly harm the eggs and indirect

  20. Investigating Effects of Invasive Species on Plant Community Structure

    Science.gov (United States)

    Franklin, Wilfred

    2008-01-01

    In this article, the author presents a field study project that explores factors influencing forest community structure and lifts the veil off of "plant blindness." This ecological study consists of three laboratories: (1) preliminary field trip to the study site; (2) plant survey; and (3) analyzing plant community structure with descriptive…

  1. Corporate Social Responsibility Agreements Model for Community ...

    African Journals Online (AJOL)

    Michael

    2016-06-01

    Jun 1, 2016 ... aspect of Corporate Social Responsibility (CSR), to the extent that often .... intentions and implemented some community development projects, the .... Environmental Protection Agency, Police and civil society to solicit their ...

  2. Community and ecosystem responses to elevational gradients

    DEFF Research Database (Denmark)

    Sundqvist, Maja K.; Sanders, Nate; Wardle, David A.

    2013-01-01

    Community structure and ecosystem processes often vary along elevational gradients. Their responses to elevation are commonly driven by changes in temperature, and many community- and ecosystem-level variables therefore frequently respond similarly to elevation across contrasting gradients...... elevational gradients for understanding community and ecosystem responses to global climate change at much larger spatial and temporal scales than is possible through conventional ecological experiments. However, future studies that integrate elevational gradient approaches with experimental manipulations...... will provide powerful information that can improve predictions of climate change impacts within and across ecosystems....

  3. Biochar and Ecosystem Restoration: Plant Ecophysiological Responses

    Science.gov (United States)

    Gale, N.; Halim, M. A.; Thomas, S. C.

    2017-12-01

    Charcoal is thought to facilitate rapid plant regeneration following fires by increasing the retention and availability of nutrients and water, increasing soil pH, and by sorbing toxic and inhibitory soil compounds - responses that have recently encouraged research on "biochar," or charcoal used as a soil amendment. Interest in biochar for use in the restoration of disturbed systems is growing; however, investigations of the effects of biochar on wild plants and trees are lacking. We present results from two experiments testing the influence of biochar on the growth and physiology of pioneers. In the first study, in a glasshouse, we examined the effects of maple biochar (10 and 20 t/ha) applied to a temperate managed forest soil on the ecophysiology of 13 herbaceous old-field species. In the second study, in field trials in Bangladesh (15 x 15 m plots), we examined the effects of acacia biochar (7.5 t/ha) on the growth of regenerating dipterocarp secondary forests. In both experiments, we measured changes in nutrient availability to help explain ecophysiological responses. Biochars enhanced the performance of early successional old-field pioneers: increasing aboveground biomass (37%), photosynthesis (17%), reproductive biomass (100%), and water use efficiency (44%), but with high species-specific variation that included negative responses. In tropical forests, biochars marginally improved the growth and recruitment of canopy dipterocarps and increased the photosynthetic performance and abundance of some, but not all, of the dominant understory species. In both experiments, growth enhancement was due to pulses of PO4-and K+ supplied by biochar in the short term; while null and negative responses were the result of nitrogen immobilization for species with high photosynthetic capacities. These results suggest that by providing a pulse of P and base cations, biochar can improve the restoration of disturbed landscapes by enhancing the physiological performance of

  4. Herbivore-induced plant responses in Brassica oleracea prevail over effects of constitutive resistance and result in enhanced herbivore attack

    NARCIS (Netherlands)

    Poelman, E.H.; van Loon, J.J.A.; Van Dam, N.M.; Dicke, M.; Vet, L.E.M.

    2010-01-01

    1. Plant responses to herbivore attack may have community-wide effects on the composition of the plant-associated insect community. Thereby, plant responses to an early-season herbivore may have profound consequences for the amount and type of future attack. 2. Here we studied the effect of

  5. Plants' responses to drought and shade environments

    African Journals Online (AJOL)

    전병기

    factors affect plants' growth, morphology, physiology and biochemistry. Many research works .... Hardwood and Conifer tree species n central Wisconsin: Influence of light regime and .... Ecotypic variation in response to light spectra in Scots ...

  6. Environmental pollution and plant responses

    Energy Technology Data Exchange (ETDEWEB)

    Agrawal, S.B.; Agrawal, M. [Banaras Hindu Univ. (India)

    1999-11-01

    This is a comprehensive book that presents and analyses the most current research on the causal factors contributing to the deteriorating environmental quality and its effect on plant performance. It presents a holistic approach to environmental problem throughout the world; covers recent trends in understanding mechanism of action individually and in combination with other factors; evaluates recent trends of information on global climatic change issues and its consequences; and gives management strategies to be followed for abating the problem.

  7. Conceptual hierarchical modeling to describe wetland plant community organization

    Science.gov (United States)

    Little, A.M.; Guntenspergen, G.R.; Allen, T.F.H.

    2010-01-01

    Using multivariate analysis, we created a hierarchical modeling process that describes how differently-scaled environmental factors interact to affect wetland-scale plant community organization in a system of small, isolated wetlands on Mount Desert Island, Maine. We followed the procedure: 1) delineate wetland groups using cluster analysis, 2) identify differently scaled environmental gradients using non-metric multidimensional scaling, 3) order gradient hierarchical levels according to spatiotem-poral scale of fluctuation, and 4) assemble hierarchical model using group relationships with ordination axes and post-hoc tests of environmental differences. Using this process, we determined 1) large wetland size and poor surface water chemistry led to the development of shrub fen wetland vegetation, 2) Sphagnum and water chemistry differences affected fen vs. marsh / sedge meadows status within small wetlands, and 3) small-scale hydrologic differences explained transitions between forested vs. non-forested and marsh vs. sedge meadow vegetation. This hierarchical modeling process can help explain how upper level contextual processes constrain biotic community response to lower-level environmental changes. It creates models with more nuanced spatiotemporal complexity than classification and regression tree procedures. Using this process, wetland scientists will be able to generate more generalizable theories of plant community organization, and useful management models. ?? Society of Wetland Scientists 2009.

  8. Plant community variability on a small area in southeastern Montana

    Science.gov (United States)

    James G. MacCracken; Daniel W. Uresk; Richard M. Hansen

    1984-01-01

    Plant communities are inherently variable due to a number of environmental and biological forces. Canopy cover and aboveground biomass were determined for understory vegetation in plant communities of a prairie grassland-forest ecotone in southeastern Montana. Vegetation units were described using polar ordination and stepwise discriminant analysis. Nine of a total of...

  9. Plant community analysis and ecology of afromontane and ...

    African Journals Online (AJOL)

    The plant communities of the forests of southwestern Ethiopia were described based on floristic analysis of the data collected between February 1995 and May 1996. Floristic analysis is based on the cover-abundance values of both woody and herbaceous species. Plant community-environment relationship was assessed ...

  10. Global environmental change effects on plant community composition trajectories depend upon management legacies

    NARCIS (Netherlands)

    Perring, Michael P.; Bernhardt-Römermann, Markus; Baeten, Lander; Midolo, Gabriele; Blondeel, Haben; Depauw, Leen; Landuyt, Dries; Maes, Sybryn L.; Lombaerde, De Emiel; Carón, Maria Mercedes; Vellend, Mark; Brunet, Jörg; Chudomelová, Markéta; Decocq, Guillaume; Diekmann, Martin; Dirnböck, Thomas; Dörfler, Inken; Durak, Tomasz; Frenne, De Pieter; Gilliam, Frank S.; Hédl, Radim; Heinken, Thilo; Hommel, Patrick; Jaroszewicz, Bogdan; Kirby, Keith J.; Kopecký, Martin; Lenoir, Jonathan; Li, Daijiang; Máliš, František; Mitchell, Fraser J.G.; Naaf, Tobias; Newman, Miles; Petřík, Petr; Reczyńska, Kamila; Schmidt, Wolfgang; Standovár, Tibor; Świerkosz, Krzysztof; Calster, Van Hans; Vild, Ondřej; Wagner, Eva Rosa; Wulf, Monika; Verheyen, Kris

    2018-01-01

    The contemporary state of functional traits and species richness in plant communities depends on legacy effects of past disturbances. Whether temporal responses of community properties to current environmental changes are altered by such legacies is, however, unknown. We expect global environmental

  11. Assessing plant community composition fails to capture impacts of white-tailed deer on native and invasive plant species.

    Science.gov (United States)

    Nuzzo, Victoria; Dávalos, Andrea; Blossey, Bernd

    2017-07-01

    Excessive herbivory can have transformative effects on forest understory vegetation, converting diverse communities into depauperate ones, often with increased abundance of non-native plants. White-tailed deer are a problematic herbivore throughout much of eastern North America and alter forest understory community structure. Reducing (by culling) or eliminating (by fencing) deer herbivory is expected to return understory vegetation to a previously diverse condition. We examined this assumption from 1992 to 2006 at Fermilab (Batavia, IL) where a cull reduced white-tailed deer ( Odocoileus virginianus ) abundance in 1998/1999 by 90 % from 24.6 to 2.5/km 2 , and at West Point, NY, where we assessed interactive effects of deer, earthworms, and invasive plants using 30 × 30 m paired fenced and open plots in 12 different forests from 2009 to 2012. We recorded not only plant community responses (species presence and cover) within 1 m 2 quadrats, but also responses of select individual species (growth, reproduction). At Fermilab, introduced Alliaria petiolata abundance initially increased as deer density increased, but then declined after deer reduction. The understory community responded to the deer cull by increased cover, species richness and height, and community composition changed but was dominated by early successional native forbs. At West Point plant community composition was affected by introduced earthworm density but not deer exclusion. Native plant cover increased and non-native plant cover decreased in fenced plots, thus keeping overall plant cover similar. At both sites native forb cover increased in response to deer reduction, but the anticipated response of understory vegetation failed to materialize at the community level. Deer-favoured forbs ( Eurybia divaricata , Maianthemum racemosum , Polygonatum pubescens and Trillium recurvatum ) grew taller and flowering probability increased in the absence of deer. Plant community monitoring fails to capture

  12. Reduction of seismic response in breeder plants

    International Nuclear Information System (INIS)

    Tajirian, F.F.; Somes, N.F.; Todeschini, R.A.

    1984-01-01

    Thin-walled vessels to be used in the Nuclear Steam Supply Systems (NSSS) of future LMFBR's will be more sensitive to seismic excitation than their equivalents used in conventional LWR plants. Optimization studies of building arrangement have indicated that embedment of future plants may be one feasible strategy for reducing seismic response. This paper presents the results of a three-dimensional soil-structure interaction analysis using the computer program SASSI. Two types of embedded buildings are considered: full embedment of the nuclear island, and embedment of the reactor cavity alone. A comparison, between the response of the embedded structure with that of a plant supported on the surface, indicates that the seismic response at the reactor vessel support ledge can be lowered by embedment of either the entire nuclear island or the reactor cavity alone. This reduction is larger when the plant is embedded in a softer site due to the increased effect of soil-structure interaction

  13. Site and plant species are important determinants of the Methylobacterium community composition in the plant phyllosphere.

    Science.gov (United States)

    Knief, Claudia; Ramette, Alban; Frances, Lisa; Alonso-Blanco, Carlos; Vorholt, Julia A

    2010-06-01

    The plant phyllosphere constitutes a habitat for numerous microorganisms; among them are members of the genus Methylobacterium. Owing to the ubiquitous occurrence of methylobacteria on plant leaves, they represent a suitable target for studying plant colonization patterns. The influence of the factor site, host plant species, time and the presence of other phyllosphere bacteria on Methylobacterium community composition and population size were evaluated in this study. Leaf samples were collected from Arabidopsis thaliana or Medicago truncatula plants and from the surrounding plant species at several sites. The abundance of cultivable Methylobacterium clearly correlated with the abundance of other phyllosphere bacteria, suggesting that methylobacteria constitute a considerable and rather stable fraction of the phyllosphere microbiota under varying environmental conditions. Automated ribosomal intergenic spacer analysis (ARISA) was applied to characterize the Methylobacterium community composition and showed the presence of similar communities on A. thaliana plants at most sites in 2 consecutive years of sampling. A substantial part of the observed variation in the community composition was explained by site and plant species, especially in the case of the plants collected at the Arabidopsis sites (50%). The dominating ARISA peaks that were detected on A. thaliana plants were found on other plant species grown at the same site, whereas some different peaks were detected on A. thaliana plants from other sites. This indicates that site-specific factors had a stronger impact on the Methylobacterium community composition than did plant-specific factors and that the Methylobacterium-plant association is not highly host plant species specific.

  14. Plant community resistance to invasion by Bromus species: The roles of community attributes, Bromus interactions with plant communities, and Bromus traits [Chapter 10

    Science.gov (United States)

    Jeanne C. Chambers; Matthew J. Germino; Jayne Belnap; Cynthia S. Brown; Eugene W. Schupp; Samuel B. St. Clair

    2016-01-01

    The factors that determine plant community resistance to exotic annual Bromus species (Bromus hereafter) are diverse and context specific. They are influenced by the environmental characteristics and attributes of the community, the traits of Bromus species, and the direct and indirect interactions of Bromus with the plant community. Environmental factors, in...

  15. Plant Invasions Associated with Change in Root-Zone Microbial Community Structure and Diversity.

    Directory of Open Access Journals (Sweden)

    Richard R Rodrigues

    Full Text Available The importance of plant-microbe associations for the invasion of plant species have not been often tested under field conditions. The research sought to determine patterns of change in microbial communities associated with the establishment of invasive plants with different taxonomic and phenetic traits. Three independent locations in Virginia, USA were selected. One site was invaded by a grass (Microstegium vimineum, another by a shrub (Rhamnus davurica, and the third by a tree (Ailanthus altissima. The native vegetation from these sites was used as reference. 16S rRNA and ITS regions were sequenced to study root-zone bacterial and fungal communities, respectively, in invaded and non-invaded samples and analyzed using Quantitative Insights Into Microbial Ecology (QIIME. Though root-zone microbial community structure initially differed across locations, plant invasion shifted communities in similar ways. Indicator species analysis revealed that Operational Taxonomic Units (OTUs closely related to Proteobacteria, Acidobacteria, Actinobacteria, and Ascomycota increased in abundance due to plant invasions. The Hyphomonadaceae family in the Rhodobacterales order and ammonia-oxidizing Nitrospirae phylum showed greater relative abundance in the invaded root-zone soils. Hyphomicrobiaceae, another bacterial family within the phyla Proteobacteria increased as a result of plant invasion, but the effect associated most strongly with root-zones of M. vimineum and R. davurica. Functional analysis using Phylogenetic Investigation of Communities by Reconstruction of Unobserved States (PICRUSt showed bacteria responsible for nitrogen cycling in soil increased in relative abundance in association with plant invasion. In agreement with phylogenetic and functional analyses, greater turnover of ammonium and nitrate was associated with plant invasion. Overall, bacterial and fungal communities changed congruently across plant invaders, and support the hypothesis that

  16. Identification of the Bacterial Community Responsible for ...

    African Journals Online (AJOL)

    Identification of bacteria community responsible for decontaminating Eleme petrochemical industrial effluent using 16S PCR denaturing gradient gel electrophoresis (DGGE) was determined. Gene profiles were determined by extracting DNA from bacterial isolates and amplified by polymerase chain reaction (PCR) using ...

  17. Strengthening Community Land Rights and Responses to ...

    International Development Research Centre (IDRC) Digital Library (Canada)

    Strengthening Community Land Rights and Responses to Involuntary Displacement Caused by Development Projects in Zimbabwe ... The construction of hydro-electric dams and other large mining and agricultural projects, for example, have led to negative consequences due to weak land tenure rights and a more general ...

  18. Advancing High Spatial and Spectral Resolution Remote Sensing for Observing Plant Community Response to Environmental Variability and Change in the Alaskan Arctic

    Science.gov (United States)

    Vargas Zesati, Sergio A.

    The Arctic is being impacted by climate change more than any other region on Earth. Impacts to terrestrial ecosystems have the potential to manifest through feedbacks with other components of the Earth System. Of particular concern is the potential for the massive store of soil organic carbon to be released from arctic permafrost to the atmosphere where it could exacerbate greenhouse warming and impact global climate and biogeochemical cycles. Even though substantial gains to our understanding of the changing Arctic have been made, especially over the past decade, linking research results from plot to regional scales remains a challenge due to the lack of adequate low/mid-altitude sampling platforms, logistic constraints, and the lack of cross-scale validation of research methodologies. The prime motivation of this study is to advance observational capacities suitable for documenting multi-scale environmental change in arctic terrestrial landscapes through the development and testing of novel ground-based and low altitude remote sensing methods. Specifically this study addressed the following questions: • How well can low-cost kite aerial photography and advanced computer vision techniques model the microtopographic heterogeneity of changing tundra surfaces? • How does imagery from kite aerial photography and fixed time-lapse digital cameras (pheno-cams) compare in their capacity to monitor plot-level phenological dynamics of arctic vegetation communities? • Can the use of multi-scale digital imaging systems be scaled to improve measurements of ecosystem properties and processes at the landscape level? • How do results from ground-based and low altitude digital remote sensing of the spatiotemporal variability in ecosystem processes compare with those from satellite remote sensing platforms? Key findings from this study suggest that cost-effective alternative digital imaging and remote sensing methods are suitable for monitoring and quantifying plot to

  19. Molecular mechanisms of plant competition: neighbour detection and response strategies

    NARCIS (Netherlands)

    Pierik, R.; Mommer, L.; Voesenek, L.A.C.J.

    2013-01-01

    Plant competition determines the diversity and species abundance of natural communities as well as potential yields in agricultural systems. Understanding the mechanisms of plant competition is instrumental to understanding plant performance in true vegetations. In this review, we will address

  20. Does a decade of elevated [CO2] affect a desert perennial plant community?

    Science.gov (United States)

    Newingham, Beth A; Vanier, Cheryl H; Kelly, Lauren J; Charlet, Therese N; Smith, Stanley D

    2014-01-01

    Understanding the effects of elevated [CO2 ] on plant community structure is crucial to predicting ecosystem responses to global change. Early predictions suggested that productivity in deserts would increase via enhanced water-use efficiency under elevated [CO2], but the response of intact arid plant communities to elevated [CO2 ] is largely unknown. We measured changes in perennial plant community characteristics (cover, species richness and diversity) after 10 yr of elevated [CO2] exposure in an intact Mojave Desert community at the Nevada Desert Free-Air CO2 Enrichment (FACE) Facility. Contrary to expectations, total cover, species richness, and diversity were not affected by elevated [CO2]. Over the course of the experiment, elevated [CO2] had no effect on changes in cover of the evergreen C3 shrub, Larrea tridentata; alleviated decreases in cover of the C4 bunchgrass, Pleuraphis rigida; and slightly reduced the cover of C3 drought-deciduous shrubs. Thus, we generally found no effect of elevated [CO2] on plant communities in this arid ecosystem. Extended drought, slow plant growth rates, and highly episodic germination and recruitment of new individuals explain the lack of strong perennial plant community shifts after a decade of elevated [CO2]. © 2013 The Authors. New Phytologist © 2013 New Phytologist Trust.

  1. Plant toxicity, adaptive herbivory, and plant community dynamics

    Science.gov (United States)

    Feng, Z.; Liu, R.; DeAngelis, D.L.; Bryant, J.P.; Kielland, K.; Stuart, Chapin F.; Swihart, R.K.

    2009-01-01

    We model effects of interspecific plant competition, herbivory, and a plant's toxic defenses against herbivores on vegetation dynamics. The model predicts that, when a generalist herbivore feeds in the absence of plant toxins, adaptive foraging generally increases the probability of coexistence of plant species populations, because the herbivore switches more of its effort to whichever plant species is more common and accessible. In contrast, toxin-determined selective herbivory can drive plant succession toward dominance by the more toxic species, as previously documented in boreal forests and prairies. When the toxin concentrations in different plant species are similar, but species have different toxins with nonadditive effects, herbivores tend to diversify foraging efforts to avoid high intakes of any one toxin. This diversification leads the herbivore to focus more feeding on the less common plant species. Thus, uncommon plants may experience depensatory mortality from herbivory, reducing local species diversity. The depensatory effect of herbivory may inhibit the invasion of other plant species that are more palatable or have different toxins. These predictions were tested and confirmed in the Alaskan boreal forest. ?? 2009 Springer Science+Business Media, LLC.

  2. A plant's perspective of extremes: terrestrial plant responses to changing climatic variability.

    Science.gov (United States)

    Reyer, Christopher P O; Leuzinger, Sebastian; Rammig, Anja; Wolf, Annett; Bartholomeus, Ruud P; Bonfante, Antonello; de Lorenzi, Francesca; Dury, Marie; Gloning, Philipp; Abou Jaoudé, Renée; Klein, Tamir; Kuster, Thomas M; Martins, Monica; Niedrist, Georg; Riccardi, Maria; Wohlfahrt, Georg; de Angelis, Paolo; de Dato, Giovanbattista; François, Louis; Menzel, Annette; Pereira, Marízia

    2013-01-01

    We review observational, experimental, and model results on how plants respond to extreme climatic conditions induced by changing climatic variability. Distinguishing between impacts of changing mean climatic conditions and changing climatic variability on terrestrial ecosystems is generally underrated in current studies. The goals of our review are thus (1) to identify plant processes that are vulnerable to changes in the variability of climatic variables rather than to changes in their mean, and (2) to depict/evaluate available study designs to quantify responses of plants to changing climatic variability. We find that phenology is largely affected by changing mean climate but also that impacts of climatic variability are much less studied, although potentially damaging. We note that plant water relations seem to be very vulnerable to extremes driven by changes in temperature and precipitation and that heat-waves and flooding have stronger impacts on physiological processes than changing mean climate. Moreover, interacting phenological and physiological processes are likely to further complicate plant responses to changing climatic variability. Phenological and physiological processes and their interactions culminate in even more sophisticated responses to changing mean climate and climatic variability at the species and community level. Generally, observational studies are well suited to study plant responses to changing mean climate, but less suitable to gain a mechanistic understanding of plant responses to climatic variability. Experiments seem best suited to simulate extreme events. In models, temporal resolution and model structure are crucial to capture plant responses to changing climatic variability. We highlight that a combination of experimental, observational, and/or modeling studies have the potential to overcome important caveats of the respective individual approaches. © 2012 Blackwell Publishing Ltd.

  3. Can biomass responses to warming at plant to ecosystem levels be predicted by leaf-level responses?

    Science.gov (United States)

    Xia, J.; Shao, J.; Zhou, X.; Yan, W.; Lu, M.

    2015-12-01

    Global warming has the profound impacts on terrestrial C processes from leaf to ecosystem scales, potentially feeding back to climate dynamics. Although numerous studies had investigated the effects of warming on C processes from leaf to plant and ecosystem levels, how leaf-level responses to warming scale up to biomass responses at plant, population, and community levels are largely unknown. In this study, we compiled a dataset from 468 papers at 300 experimental sites and synthesized the warming effects on leaf-level parameters, and plant, population and ecosystem biomass. Our results showed that responses of plant biomass to warming mainly resulted from the changed leaf area rather than the altered photosynthetic capacity. The response of ecosystem biomass to warming was weaker than those of leaf area and plant biomass. However, the scaling functions from responses of leaf area to plant biomass to warming were different in diverse forest types, but functions were similar in non-forested biomes. In addition, it is challenging to scale the biomass responses from plant up to ecosystem. These results indicated that leaf area might be the appropriate index for plant biomass response to warming, and the interspecific competition might hamper the scaling of the warming effects on plant and ecosystem levels, suggesting that the acclimation capacity of plant community should be incorporated into land surface models to improve the prediction of climate-C cycle feedback.

  4. Restructuring of Endophytic Bacterial Communities in Grapevine Yellows-Diseased and Recovered Vitis vinifera L. Plants

    Science.gov (United States)

    Bulgari, Daniela; Casati, Paola; Crepaldi, Paola; Daffonchio, Daniele; Quaglino, Fabio; Brusetti, Lorenzo; Bianco, Piero Attilio

    2011-01-01

    Length heterogeneity-PCR assays, combined with statistical analyses, highlighted that the endophytic bacterial community associated with healthy grapevines was characterized by a greater diversity than that present in diseased and recovered plants. The findings suggest that phytoplasmas can restructure the bacterial community by selecting endophytic strains that could elicit a plant defense response. PMID:21622794

  5. Integrating plant ecological responses to climate extremes from individual to ecosystem levels.

    Science.gov (United States)

    Felton, Andrew J; Smith, Melinda D

    2017-06-19

    Climate extremes will elicit responses from the individual to the ecosystem level. However, only recently have ecologists begun to synthetically assess responses to climate extremes across multiple levels of ecological organization. We review the literature to examine how plant responses vary and interact across levels of organization, focusing on how individual, population and community responses may inform ecosystem-level responses in herbaceous and forest plant communities. We report a high degree of variability at the individual level, and a consequential inconsistency in the translation of individual or population responses to directional changes in community- or ecosystem-level processes. The scaling of individual or population responses to community or ecosystem responses is often predicated upon the functional identity of the species in the community, in particular, the dominant species. Furthermore, the reported stability in plant community composition and functioning with respect to extremes is often driven by processes that operate at the community level, such as species niche partitioning and compensatory responses during or after the event. Future research efforts would benefit from assessing ecological responses across multiple levels of organization, as this will provide both a holistic and mechanistic understanding of ecosystem responses to increasing climatic variability.This article is part of the themed issue 'Behavioural, ecological and evolutionary responses to extreme climatic events'. © 2017 The Author(s).

  6. Effects of migratory geese on plant communities of an Alaskan salt marsh

    Science.gov (United States)

    Zacheis, Amy B.; Hupp, Jerry W.; Ruess, Roger W.

    2001-01-01

    1. We studied the effects of lesser snow geese (Anser caerulescens caerulescens) and Canada geese (Branta canadensis) on two salt marsh plant communities in Cook Inlet, Alaska, a stopover area used during spring migration. From 1995 to 1997 we compared plant species composition and biomass on plots where geese were excluded from feeding with paired plots where foraging could occur. 2. Foraging intensity was low (650-1930 goose-days km-2) compared to other goose-grazing systems. 3. Canada geese fed mainly on above-ground shoots of Triglochin maritimum, Puccinellia spp. and Carex ramenskii, whereas the majority of the snow goose diet consisted of below-ground tissues of Plantago maritima and Triglochin maritimum. 4. Plant communities responded differently to goose herbivory. In the sedge meadow community, where feeding was primarily on above-ground shoots, there was no effect of grazing on the dominant species Carex ramenskii and Triglochin maritimum. In the herb meadow community, where snow geese fed on Plantago maritima roots and other below-ground tissues, there was a difference in the relative abundance of plant species between treatments. Biomass of Plantago maritima and Potentilla egedii was lower on grazed plots compared with exclosed, whereas biomass of Carex ramenskii was greater on grazed plots. There was no effect of herbivory on total standing crop biomass in either community. The variable effect of herbivory on Carex ramenskii between communities suggests that plant neighbours and competitive interactions are important factors in a species' response to herbivory. In addition, the type of herbivory (above- or below-ground) was important in determining plant community response to herbivory. 5. Litter accumulation was reduced in grazed areas compared with exclosed in both communities. Trampling of the previous year's litter into the soil surface by geese incorporated more litter into soils in grazed areas. 6. This study illustrates that even light herbivore

  7. Community stakeholder responses to advocacy advertising

    Energy Technology Data Exchange (ETDEWEB)

    Miller, B.; Sinclair, J. [Elon University, Elon, NC (United States). School Community

    2009-07-01

    Focus group research was used to examine how community stakeholders, a group with local industry experience, responded to coal industry advocacy messages. The stakeholders expressed beliefs about both the advertiser and the coal industry, and while their knowledge led to critical consideration of the industry campaign, they also expressed a desire to identify with positive messages about their community. Applying a postpositivist research perspective, a new model is introduced to integrate these beliefs in terms of advertiser trust and industry accountability under the existing theoretical framework of persuasion knowledge. Agent and topic knowledge are combined in this model based on responses to the industry advocacy campaign. In doing so, this study integrates a priori theory within a new context, extending the current theoretical framework to include an understanding of how community stakeholders - a common target for marketplace advocacy - interpret industry messages.

  8. Gap Assessment in the Emergency Response Community

    Energy Technology Data Exchange (ETDEWEB)

    Barr, Jonathan L.; Burtner, Edwin R.; Pike, William A.; Peddicord, Annie M Boe; Minsk, Brian S.

    2010-09-27

    This report describes a gap analysis of the emergency response and management (EM) community, performed during the fall of 2009. Pacific Northwest National Laboratory (PNNL) undertook this effort to identify potential improvements to the functional domains in EM that could be provided by the application of current or future technology. To perform this domain-based gap analysis, PNNL personnel interviewed subject matter experts (SMEs) across the EM domain; to make certain that the analyses reflected a representative view of the community, the SMEs were from a variety of geographic areas and from various sized communities (urban, suburban, and rural). PNNL personnel also examined recent and relevant after-action reports and U.S. Government Accountability Office reports.

  9. Abiotic drivers of Chihuahuan Desert plant communities

    Science.gov (United States)

    Laura Marie Ladwig

    2014-01-01

    Within grasslands, precipitation, fire, nitrogen (N) addition, and extreme temperatures influence community composition and ecosystem function. The differential influences of these abiotic factors on Chihuahuan Desert grassland communities was examined within the Sevilleta National Wildlife Refuge, located in central New Mexico, U.S.A. Although fire is a natural...

  10. Augmenting Plant Immune Responses and Biological Control by Microbial Determinants

    Directory of Open Access Journals (Sweden)

    Sang Moo Lee

    2015-09-01

    Full Text Available Plant have developed sophisticated defence mechanisms against microbial pathogens. The recent accumulated information allow us to understand the nature of plant immune responses followed by recognition of microbial factors/determinants through cutting-edge genomics and multi-omics techniques. However, the practical approaches to sustain plant health using enhancement of plant immunity is yet to be fully appreciated. Here, we overviewed the general concept and representative examples on the plant immunity. The fungal, bacterial, and viral determinants that was previously reported as the triggers of plant immune responses are introduced and described as the potential protocol of biological control. Specifically, the role of chitin, glucan, lipopolysaccharides/extracellular polysaccharides, microbe/pathogen-associated molecular pattern, antibiotics, mimic-phytohormones, N-acyl homoserine lactone, harpin, vitamins, and volatile organic compounds are considered. We hope that this review stimulates scientific community and farmers to broaden their knowledge on the microbial determinant-based biological control and to apply the technology on the integrated pest management program.

  11. Herbivory and dominance shifts among exotic and congeneric native plant species during plant community establishment

    DEFF Research Database (Denmark)

    Engelkes, Tim; Meisner, Annelein; Morriën, Elly

    2016-01-01

    in a riparian ecosystem during early establishment of invaded communities. We planted ten plant communities each consisting of three individuals of each of six exotic plant species as well as six phylogenetically related natives. Exotic plant species were selected based on a rapid recent increase in regional...... abundance, the presence of a congeneric native species, and their co-occurrence in the riparian ecosystem. All plant communities were covered by tents with insect mesh. Five tents were open on the leeward side to allow herbivory. The other five tents were completely closed in order to exclude insects...... and vertebrates. Herbivory reduced aboveground biomass by half and influenced which of the plant species dominated the establishing communities. Exposure to herbivory did not reduce the total biomass of natives more than that of exotics, so aboveground herbivory did not selectively enhance exotics during...

  12. Dynamic Frequency Response of Wind Power Plants

    DEFF Research Database (Denmark)

    Altin, Müfit

    according to their grid codes. In these scenarios particularly with high wind power penetration cases, conventional power plants (CPPs) such as old thermal power plants are planned to be replaced with wind power plants (WPPs). Consequently, the power system stability will be affected and the control...... to maintain sustainable and reliable operation of the power system for these targets, transmission system operators (TSOs) have revised the grid code requirements. Also, the TSOs are planning the future development of the power system with various wind penetration scenarios to integrate more wind power...... capability of WPPs would be investigated. The objective of this project is to analyze and identify the power system requirements for the synchronizing power support and inertial response control of WPPs in high wind power penetration scenarios. The dynamic frequency response of WPPs is realized...

  13. Measuring competition in plant communities where it is difficult to distinguish individual plants

    DEFF Research Database (Denmark)

    Damgaard, Christian

    2011-01-01

    A novel method for measuring plant-plant interactions in undisturbed semi-natural and natural plant communities where it is difficult to distinguish individual plants is discussed. It is assumed that the ecological success of the different plant species in the plant community may be adequately...... measured by plant cover and vertical density (a measure that is correlated to the 3-dimensional space occupancy and biomass). Both plant cover and vertical density are measured in a standard pin-point analysis in the beginning and at the end of the growing season. In the outlined competition model....... The method allows direct measurements of the competitive effects of neighbouringzplants on plant performance and the estimation of parameters that describe the ecological processes of plantplant interactions during the growing season as well as the process of survival and recruitment between growing seasons...

  14. Evapotranspiration in three plant communities of a Rhigozum ...

    African Journals Online (AJOL)

    Evapotranspiration losses in three Rhigozum trichotomum plant communities namely, pure grass, pure R. trichotomum and a mixed stand of grass and R. trichotomum were determined during the 1985-86 growing season. Three hydrologically isolated plots in each community type were irrigated and changes in soil water ...

  15. Vertebrate herbivores influence soil nematodes by modifying plant communities

    NARCIS (Netherlands)

    Veen, G. F. (Ciska); Olff, Han; Duyts, Henk; van der Putten, Wim H.

    Abiotic soil properties, plant community composition, and herbivory all have been reported as important factors influencing the composition of soil communities. However, most studies thus far have considered these factors in isolation, whereas they strongly interact in the field. Here, we study how

  16. Structure and composition of oligohaline marsh plant communities exposed to salinity pulses

    Science.gov (United States)

    Howard, R.J.; Mendelssohn, I.A.

    2000-01-01

    The response of two oligohaline marsh macrophyte communities to pulses of increased salinity was studied over a single growing season in a greenhouse experiment. The plant communities were allowed a recovery period in freshwater following the pulse events. The experimental treatments included: (1) salinity influx rate (rate of salinity increase from 0 to 12 gl-1); (2) duration of exposure to elevated salinity; and (3) water depth. The communities both included Sagittaria lancifolia L.; the codominant species were Eleocharis palustris (L.) Roemer and J.A. Schultes in community 1 and Schoenoplectus americanus (Pers.) Volk. ex Schinz and R. Keller in community 2. Effects of the treatments on sediment chemical characteristics (salinity, pH, redox potential, and sulfide and ammonium concentrations) and plant community attributes (aboveground and belowground biomass, stem density, leaf tissue nutrients, and species richness) were examined. The treatment effects often interacted to influence sediment and plant communities characteristics following recovery in fresh water. Salinity influx rate per se, however, had little effect on the abiotic or biotic response variables; significant influx effects were found when the 0 gl-1 (zero influx) treatment was compared to the 12 gl-1 treatments, regardless of the rate salinity was raised. A salinity level of 12 gl-1 had negative effects on plant community structure and composition; these effects were usually associated with 3 months of salinity exposure. Water depth often interacted with exposure duration, but increased water depth did independently decrease the values of some community response measures. Community 1 was affected more than community 2 in the most extreme salinity treatment (3 months exposure/15-cm water depth). Although species richness in both communities was reduced, structural changes were more dramatic in community 1. Biomass and stem density were reduced in community 1 overall and in both dominant species

  17. Conservation and restoration of indigenous plants to improve community livelihoods: the Useful Plants Project

    Science.gov (United States)

    Ulian, Tiziana; Sacandé, Moctar; Mattana, Efisio

    2014-05-01

    Kew's Millennium Seed Bank partnership (MSBP) is one of the largest ex situ plant conservation initiatives, which is focused on saving plants in and from regions most at risk, particularly in drylands. Seeds are collected and stored in seed banks in the country of origin and duplicated in the Millennium Seed Bank in the UK. The MSBP also strengthens the capacity of local communities to successfully conserve and sustainably use indigenous plants, which are important for their wellbeing. Since 2007, high quality seed collections and research information have been gathered on ca. 700 useful indigenous plant species that were selected by communities in Botswana, Kenya, Mali, Mexico and South Africa through Project MGU - The Useful Plants Project. These communities range from various farmer's groups and organisations to traditional healers, organic cotton/crop producers and primary schools. The information on seed conservation and plant propagation was used to train communities and to propagate ca. 200 species that were then planted in local gardens, and as species reintroduced for reforestation programmes and enriching village forests. Experimental plots have also been established to further investigate the field performance (plant survival and growth rate) of indigenous species, using low cost procedures. In addition, the activities support revenue generation for local communities directly through the sustainable use of plant products or indirectly through wider environmental and cultural services. This project has confirmed the potential of biodiversity conservation to improve food security and human health, enhance community livelihoods and strengthen the resilience of land and people to the changing climate. This approach of using indigenous species and having local communities play a central role from the selection of species to their planting and establishment, supported by complementary research, may represent a model for other regions of the world, where

  18. Rural and school community in appreciating knowledge on medical plants

    Directory of Open Access Journals (Sweden)

    Marcílio Souza Carneiro

    2016-05-01

    Isolated communities in the urban environment still use medicinal plants, but such knowledge is not always passed on to new generations. In this scenario, we propose a study with students, teachers, and community residents from Córrego da Ema, Amontada, Ceará, Brazil, aiming to know the wisdom of medicinal plants in a small rural community in the Brazilian semi-arid region. We interviewed the medicinal plant connoisseurs, named as local experts, by using the “snow ball” method. We applied questionnaires to investigate Elementary School students’ knowledge on medicinal plants (pre-tour. These actions provided a basis for planning guided-tours, activities aimed at 51 students, which we carried out along with the 10 experts and 2 local school teachers, whose results (post-tour were assessed by using the same pre-tour questionnaire. Most local experts were women (80%, their families had many people and low education level, factors that contribute to using medicinal plants. Experts cited 35 medicinal plant species. Students cited 24 pre-tour plant species and 28 post-tour plant species. Students increased their knowledge, as there was also a post-tour increase in therapeutic indications and preparation methods, as mentioned. The school played an important role in appreciating this intangible heritage, because it enabled actions involving formal and informal education.

  19. Rural and school community in appreciating knowledge on medical plants

    Directory of Open Access Journals (Sweden)

    Marcílio Souza Carneiro

    2016-05-01

    Full Text Available Isolated communities in the urban environment still use medicinal plants, but such knowledge is not always passed on to new generations. In this scenario, we propose a study with students, teachers, and community residents from Córrego da Ema, Amontada, Ceará, Brazil, aiming to know the wisdom of medicinal plants in a small rural community in the Brazilian semi-arid region. We interviewed the medicinal plant connoisseurs, named as local experts, by using the “snow ball” method. We applied questionnaires to investigate Elementary School students’ knowledge on medicinal plants (pre-tour. These actions provided a basis for planning guided-tours, activities aimed at 51 students, which we carried out along with the 10 experts and 2 local school teachers, whose results (post-tour were assessed by using the same pre-tour questionnaire. Most local experts were women (80%, their families had many people and low education level, factors that contribute to using medicinal plants. Experts cited 35 medicinal plant species. Students cited 24 pre-tour plant species and 28 post-tour plant species. Students increased their knowledge, as there was also a post-tour increase in therapeutic indications and preparation methods, as mentioned. The school played an important role in appreciating this intangible heritage, because it enabled actions involving formal and informal education.

  20. Coal mining activities change plant community structure due to air pollution and soil degradation.

    Science.gov (United States)

    Pandey, Bhanu; Agrawal, Madhoolika; Singh, Siddharth

    2014-10-01

    The aim of this study was to investigate the effects of coal mining activities on the community structures of woody and herbaceous plants. The response of individual plants of community to defilement caused by coal mining was also assessed. Air monitoring, soil physico-chemical and phytosociological analyses were carried around Jharia coalfield (JCF) and Raniganj coalfield. The importance value index of sensitive species minified and those of tolerant species enhanced with increasing pollution load and altered soil quality around coal mining areas. Although the species richness of woody and herbaceous plants decreased with higher pollution load, a large number of species acclimatized to the stress caused by the coal mining activities. Woody plant community at JCF was more affected by coal mining than herbaceous community. Canonical correspondence analysis revealed that structure of herbaceous community was mainly driven by soil total organic carbon, soil nitrogen, whereas woody layer community was influenced by sulphur dioxide in ambient air, soil sulphate and soil phosphorus. The changes in species diversity observed at mining areas indicated an increase in the proportion of resistant herbs and grasses showing a tendency towards a definite selection strategy of ecosystem in response to air pollution and altered soil characteristics.

  1. Plant control impact on IFR power plant passive safety response

    International Nuclear Information System (INIS)

    Vilim, R.B.

    1993-01-01

    A method is described for optimizing the closed-loop plant control strategy with respect to safety margins sustained in the unprotected upset response of a liquid metal reactor. The optimization is performed subject to the normal requirements for reactor startup, load change and compensation for reactivity changes over the cycle. The method provides a formal approach to the process of exploiting the innate self-regulating property of a metal fueled reactor to make it less dependent on operator action and less vulnerable to automatic control system fault and/or operator error

  2. Root-associated fungal community response to drought-associated changes in vegetation community.

    Science.gov (United States)

    Dean, Sarah L; Warnock, Daniel D; Litvak, Marcy E; Porras-Alfaro, Andrea; Sinsabaugh, Robert

    2015-01-01

    Recent droughts in southwestern USA have led to large-scale mortality of piñon (Pinus edulis) in piñon-juniper woodlands. Piñon mortality alters soil moisture, nutrient and carbon availability, which could affect the root-associated fungal (RAF) communities and therefore the fitness of the remaining plants. We collected fine root samples at a piñon-juniper woodland and a juniper savannah site in central New Mexico. Roots were collected from piñon and juniper (Juniperus monosperma) trees whose nearest neighbors were live piñon, live juniper or dead piñon. RAF communities were analyzed by 454 pyrosequencing of the universal fungal ITS region. The most common taxa were Hypocreales and Chaetothyriales. More than 10% of ITS sequences could not be assigned taxonomy at the phylum level. Two of the unclassified OTUs significantly differed between savanna and woodland, had few like sequences in GenBank and formed new fungal clades with other unclassified RAF from arid plants, highlighting how little study has been done on the RAF of arid ecosystems. Plant host or neighbor did not affect RAF community composition. However, there was a significant difference between RAF communities from woodland vs. savanna, indicating that abiotic factors such as temperature and aridity might be more important in structuring these RAF communities than biotic factors such as plant host or neighbor identity. Ectomycorrhizal fungi (EM) were present in juniper as well as piñon in the woodland site, in contrast with previous research, but did not occur in juniper savanna, suggesting a potential shared EM network with juniper. RAF richness was lower in hosts that were neighbors of the opposite host. This may indicate competitive exclusion between fungi from different hosts. Characterizing these communities and their responses to environment and plant neighborhood is a step toward understanding the effects of drought on a biome that spans 19,000,000 ha of southwestern USA. © 2015 by The

  3. Linking above and belowground responses to global change at community and ecosystem scales.

    Energy Technology Data Exchange (ETDEWEB)

    Antoninka, Anita [Northern Arizona University; Wolf, Julie [Northern Arizona University; Bowker, Matt [Northern Arizona University; Classen, Aimee T [ORNL; JohnsonPhD, Dr Nancy C [Northern Arizona University

    2009-01-01

    Cryptic belowground organisms are difficult to observe and their responses to global changes are not well understood. Nevertheless, there is reason to believe that interactions among above- and belowground communities may mediate ecosystem responses to global change. We used grassland mesocosms to manipulate the abundance of one important group of soil organisms, arbuscular mycorrhizal (AM) fungi, and to study community and ecosystem responses to CO2 and N enrichment. After two growing seasons, biomass responses of plant communities were recorded, and soil community responses were measured using microscopy, phospholipid fatty acids (PLFA) and community-level physiological profiles (CLPP). Ecosystem responses were examined by measuring net primary production (NPP), evapotranspiration, total soil organic matter (SOM), and extractable mineral N. Structural equation modeling was used to examine the causal relationships among treatments and response variables. We found that while CO2 and N tended to directly impact ecosystem functions (evapotranspiration and NPP, respectively), AM fungi indirectly impacted ecosystem functions by strongly influencing the composition of plant and soil communities. For example, the presence of AM fungi had a strong influence on other root and soil fungi and soil bacteria. We found that the mycotrophic status of the dominant plant species in the mesocosms determined whether the presence of AM fungi increased or decreased NPP. Mycotrophic grasses dominated the mesocosm communities during the first growing season, and thus, the mycorrhizal treatments had the highest NPP. In contrast, non-mycotrophic forbs were dominant during the second growing season and thus, the mycorrhizal treatments had the lowest NPP. The composition of the plant community strongly influenced soil N; and the composition of the soil organisms strongly influenced SOM accumulation in the mesocosms. These results show how linkages between above- and belowground communities

  4. Genetic diversity within a dominant plant outweighs plant species diversity in structuring an arthropod community.

    Science.gov (United States)

    Crawford, Kerri M; Rudgers, Jennifer A

    2013-05-01

    Plant biodiversity is being lost at a rapid rate. This has spurred much interest in elucidating the consequences of this loss for higher trophic levels. Experimental tests have shown that both plant species diversity and genetic diversity within a plant species can influence arthropod community structure. However, the majority of these studies have been conducted in separate systems, so their relative importance is currently unresolved. Furthermore, potential interactions between the two levels of diversity, which likely occur in natural systems, have not been investigated. To clarify these issues, we conducted three experiments in a freshwater sand dune ecosystem. We (1) independently manipulated plant species diversity, (2) independently manipulated genetic diversity within the dominant plant species, Ammophila breviligulata, and (3) jointly manipulated genetic diversity within the dominant plant and species diversity. We found that genetic diversity within the dominant plant species, Ammophila breviligulata, more strongly influenced arthropod communities than plant species diversity, but this effect was dependent on the presence of other species. In species mixtures, A. breviligulata genetic diversity altered overall arthropod community composition, and arthropod richness and abundance peaked at the highest level of genetic diversity. Positive nonadditive effects of diversity were detected, suggesting that arthropods respond to emergent properties of diverse plant communities. However, in the independent manipulations where A. breviligulata was alone, effects of genetic diversity were weaker, with only arthropod richness responding. In contrast, plant species diversity only influenced arthropods when A. breviligulata was absent, and then only influenced herbivore abundance. In addition to showing that genetic diversity within a dominant plant species can have large effects on arthropod community composition, these results suggest that understanding how species

  5. Plant reproduction is altered by simulated herbicide drift to constructed plant communities

    Science.gov (United States)

    Herbicide drift may have unintended impacts on native vegetation, adversely affecting structure and function of plant communities. However, these potential effects have been rarely studied or quantified. To determine potential ecological effects of herbicide drift, we construct...

  6. Management of plant communities on set-aside land and its effects on earthworm communities

    Czech Academy of Sciences Publication Activity Database

    Gormsen, D.; Hedlund, K.; Korthals, G. W.; Mortimer, S. R.; Pižl, Václav; Šmilauerová, M.; Sugg, E.

    2004-01-01

    Roč. 40, 3-4 (2004), s. 123-128 ISSN 1164-5563 Grant - others:Evropská unie(XE) ENV4-CT95-0002 Keywords : earthworm community * plant community * land use Subject RIV: EH - Ecology, Behaviour Impact factor: 0.776, year: 2004

  7. Evolutionary responses of native plant species to invasive plants : a review

    OpenAIRE

    Oduor, Ayub M. O.

    2013-01-01

    Strong competition from invasive plant species often leads to declines in abundances and may,in certain cases, cause localized extinctions of native plant species. Nevertheless, studies have shown that certain populations of native plant species can co-exist with invasive plant species, suggesting the possibility of adaptive evolutionary responses of those populations to the invasive plants. Empirical inference of evolutionary responses of the native plant species to invasive plants has invol...

  8. Does responsiveness to arbuscular mycorrhizas depend on plant invasive status?

    Science.gov (United States)

    1. Some posit invasive alien plants are less dependent on mycorrhizal associations than native plants, and thus weak mycorrhizal responsiveness may be a general mechanism of plant invasion. 2. Here, we tested whether mycorrhizal responsiveness varies by plant invasive status while controlling for ph...

  9. Negative Plant-Soil Feedback and Positive Species Interaction in a Herbaceous Plant Community

    NARCIS (Netherlands)

    Bonanomi, G.; Rietkerk, M.; Dekker, S.C.; Mazzoleni, S.

    2005-01-01

    Increasing evidence shows that facilitative interaction and negative plant¿soil feedback are driving factors of plant population dynamics and community processes. We studied the intensity and the relative impact of negative feedback on clonal growth and seed germination of Scirpus holoschoenus, a

  10. Plant Communities Suitable for Green Roofs in Arid Regions

    Directory of Open Access Journals (Sweden)

    Rachel Gioannini

    2018-05-01

    Full Text Available In extensive green roof settings, plant communities can be more robust than monocultures. In addition, native plants might be hardier and more ecologically sound choices than non-native plants in green roof systems. The objectives of this research were to (1 compare the performance of plant communities with that of monocultures and (2 compare the growth of natives to non-natives in a simulated green roof setting. We conducted a two-year experiment at an outdoor site in a desert environment using four plant morphological types (groundcover, forb, succulent and grass. Native plants selected were Chrysactinia mexicana, Melampodium leucanthum, Euphorbia antisyphilitica, and Nassella tenuissima, and non-natives were Delosperma nubigenum, Stachys byzantina, Sedum kamtschiaticum and Festuca glauca. Plants were assigned randomly to either monoculture or community and grown in 1 m × 1 m custom-built trays filled with 15 cm of a proprietary blend of 50/20/30 lightweight aggregate/sand/compost (by volume. Native forb, Melampodium, in community had greater coverage for four of the five measurements in the first year over native forb in monoculture and non-native forb regardless of setting. Native forb coverage was also greater than non-native forb for three of the four measurements in year 2, regardless of setting. Coverage of native grass was significantly greater than non-native grasses throughout the experiment. Coverage was also greater for eight of nine measurements for native succulent over non-natives succulent. However, non-native groundcover coverage was significantly greater than native groundcover for seven of nine measurements. On 1 November 2016, relative water content (RWC for succulents (p = 0.0424 was greatest for native Euphorbia in monoculture at 88%. Native Euphorbia also had greater RWC than non-native Sedum on 4 April 2017 (78% and 4 July 2017 (80%. However, non-native Sedum had greater root length (6548 cm, root dry weight (12.1 g

  11. Summer freezing resistance: a critical filter for plant community assemblies in Mediterranean high mountains

    Directory of Open Access Journals (Sweden)

    David Sánchez Pescador

    2016-02-01

    Full Text Available Assessing freezing community response and whether freezing resistance is related to other functional traits is essential for understanding alpine community assemblages, particularly in Mediterranean environments where plants are exposed to freezing temperatures and summer droughts. Thus, we characterized the leaf freezing resistance of 42 plant species in 38 plots at Sierra de Guadarrama (Spain by measuring their ice nucleation temperature, freezing point (FP, and low-temperature damage (LT50, as well as determining their freezing resistance mechanisms (i.e., tolerance or avoidance. The community response to freezing was estimated for each plot as community weighted means (CWMs and functional diversity, and we assessed their relative importance with altitude. We established the relationships between freezing resistance, growth forms, and four key plant functional traits (i.e., plant height, specific leaf area, leaf dry matter content, and seed mass. There was a wide range of freezing resistance responses and more than in other alpine habitats. At the community level, the CWMs of FP and LT50 responded negatively to altitude, whereas the functional diversity of both traits increased with altitude. The proportion of freezing-tolerant species also increased with altitude. The ranges of FP and LT50 varied among growth forms, and only the leaf dry matter content correlated negatively with freezing-resistance traits. Summer freezing events represent important abiotic filters for assemblies of Mediterranean high mountain communities, as suggested by the CWMs. However, a concomitant summer drought constraint may also explain the high freezing resistance of species that thrive in these areas and the lower functional diversity of freezing resistance traits at lower altitudes. Leaves with high dry matter contents may maintain turgor at lower water potential and enhance drought tolerance in parallel to freezing resistance. This adaptation to drought seems to

  12. Macrophyte Community Response to Nitrogen Loading and ...

    Science.gov (United States)

    Empirical determination of nutrient loading thresholds that negatively impact seagrass communities have been elusive due to the multitude of factors involved. Using a mesocosm system that simulated Pacific Northwest estuaries, we evaluated macrophyte metrics across gradients of NO3 loading (0, 1.5, 3 and 6x ambient) and temperature (10 and 20 °C). Macroalgal growth, biomass, and C:N responded positively to increased NO3 load and floating algal mats developed at 20 ºC. Zostera japonica metrics, including C:N, responded more to temperature than to NO3 loading. Z. marina biomass exhibited a negative temperature effect and in some cases a negative NO3 effect, while growth rate increased with temperature. Shoot survival decreased at 20 ºC but was not influenced by NO3 loading. Wasting disease index exhibited a significant temperature by NO3 interaction consistent with increased disease susceptibility. Community shifts observed were consistent with the nutrient loading hypothesis at 20 ºC, but there was no evidence of other eutrophication symptoms due to the short residence time. The Nutrient Pollution Index tracked the NO3 gradient at 10 ºC but exhibited no response at 20 ºC. We suggest that systems characterized by cool temperatures, high NO3 loads, and short residence time may be resilient to many symptoms of eutrophication. Estuarine systems characterized by cool temperatures, high nutrient loads and rapid flushing may be resilient to some symptoms

  13. Community functional responses to soil and climate at multiple spatial scales: when does intraspecific variation matter?

    Directory of Open Access Journals (Sweden)

    Andrew Siefert

    Full Text Available Despite increasing evidence of the importance of intraspecific trait variation in plant communities, its role in community trait responses to environmental variation, particularly along broad-scale climatic gradients, is poorly understood. We analyzed functional trait variation among early-successional herbaceous plant communities (old fields across a 1200-km latitudinal extent in eastern North America, focusing on four traits: vegetative height, leaf area, specific leaf area (SLA, and leaf dry matter content (LDMC. We determined the contributions of species turnover and intraspecific variation to between-site functional dissimilarity at multiple spatial scales and community trait responses to edaphic and climatic factors. Among-site variation in community mean trait values and community trait responses to the environment were generated by a combination of species turnover and intraspecific variation, with species turnover making a greater contribution for all traits. The relative importance of intraspecific variation decreased with increasing geographic and environmental distance between sites for SLA and leaf area. Intraspecific variation was most important for responses of vegetative height and responses to edaphic compared to climatic factors. Individual species displayed strong trait responses to environmental factors in many cases, but these responses were highly variable among species and did not usually scale up to the community level. These findings provide new insights into the role of intraspecific trait variation in plant communities and the factors controlling its relative importance. The contribution of intraspecific variation to community trait responses was greatest at fine spatial scales and along edaphic gradients, while species turnover dominated at broad spatial scales and along climatic gradients.

  14. The Significance of Community to Business Social Responsibility.

    Science.gov (United States)

    Besser, Terry L.

    1998-01-01

    Interviews with 1008 business owners and managers in 30 small Iowa communities found that the majority were committed to their community and provided support to youth programs, local schools, or community development activities. Business social responsibility was related to operator age, education, success, and perceptions of community collective…

  15. Plant Community Diversity After Herbicide Control of Spotted Knapweed

    OpenAIRE

    United States Department of Agriculture, Forest Service

    1992-01-01

    Herbicides were applied to four west-central Montana sites with light to moderate spotted knapweed (Centaurea maculosa Lam.) infestations. Althought knapweed suppression was high, 2 years after the spraying the communities were not converted to grass monocultures. No large declines in plant diversity were caused by the herbicides, and small depressions were probably transitory. By the third year, diversity had increased.

  16. Vascular plant diversity and community Structure of nandi forests ...

    African Journals Online (AJOL)

    Abundance data of species was used for species diversity, similarity, species richness estimation and plant community analysis. PC-ORD, CANOCO and EstimateS were used to analyze the data. A total of 321 species ... Keywords: floristic composition, ordination, rarefaction, species accumulation, species richness.

  17. Functional diversity in plant communities: Theory and analysis ...

    African Journals Online (AJOL)

    Plant functional diversity in community has become a key point in ecology studies recently. The development of species functional diversity was reviewed in the present work. Based on the former original research papers and reviews, we discussed the concept and connotation and put forward a new definition of functional ...

  18. A baseline classification of riparian woodland plant communities in ...

    African Journals Online (AJOL)

    The plots were placed along a gradient from the main water body to the drier fringe of the riparian zone. Plant species present in each plot were recorded with their estimated percentage cover using the Braun–Blanquet cover abundance scale. Hierarchical cluster analysis was used to determine vegetation communities.

  19. Plant community development is affected by nutrients and soil biota

    NARCIS (Netherlands)

    De Deyn, G.B.; Raaijmakers, C.E.; Van der Putten, W.H.

    2004-01-01

    1 Plant community development depends to a great extent on the availability of soil nutrients, but recent studies underline the role of symbiotic, herbivorous and pathogenic soil biota. We tested for interactions between these biotic and abiotic factors by studying the effects of additional

  20. Andean shrublands of Moquegua, South Peru: Prepuna plant communities

    NARCIS (Netherlands)

    Montesinos, D.B.; Cleef, A.M.; Sykora, K.V.

    2012-01-01

    A syntaxonomic overview of shrubland vegetation in the southern Andean regions of Peru is presented. For each plant community, information is given on physiognomy, floristic diversity, ecology and geographical distribution. The shrub vegetation on the slopes of the upper Tambo river valley includes

  1. The nuclear power plant and the host community

    International Nuclear Information System (INIS)

    Olsson, G.

    1978-01-01

    A councillor from a small Swedish community (Kaevlinge) in the vicinity of the Barsebaeck nuclear power plant describes the effects which the plant has had on neighbouring communities. The effect on the labour market has been small at Kaevlinge, both during routine operation and construction phases. This is however, a fairly densely populated area with a population of half a million in a radius of 30 km. The situation is different at Oskarshamn or Oesthammar. Neither has there been any special economic benefit, due to Swedish taxation laws. There has been little local anxiety due to the proximity of the nuclear power plant. Certain local planning problems have been caused by restricted zones and power cables. Cooperation between the local authorities and the utility has been good. (JIW)

  2. Effects of Trampling Limitation on Coastal Dune Plant Communities

    Science.gov (United States)

    Santoro, Riccardo; Jucker, Tommaso; Prisco, Irene; Carboni, Marta; Battisti, Corrado; Acosta, Alicia T. R.

    2012-03-01

    Sandy coastlines are sensitive ecosystems where human activities can have considerable negative impacts. In particular, trampling by beach visitors is a disturbance that affects dune vegetation both at the species and community level. In this study we assess the effects of the limitation of human trampling on dune vegetation in a coastal protected area of Central Italy. We compare plant species diversity in two recently fenced sectors with that of an unfenced area (and therefore subject to human trampling) using rarefaction curves and a diversity/dominance approach during a two year study period. Our results indicate that limiting human trampling seems to be a key factor in driving changes in the plant diversity of dune systems. In 2007 the regression lines of species abundance as a function of rank showed steep slopes and high Y-intercept values in all sectors, indicating a comparable level of stress and dominance across the entire study site. On the contrary, in 2009 the regression lines of the two fenced sectors clearly diverge from that of the open sector, showing less steep slopes. This change in the slopes of the tendency lines, evidenced by the diversity/dominance diagrams and related to an increase in species diversity, suggests the recovery of plant communities in the two fences between 2007 and 2009. In general, plant communities subject to trampling tended to be poorer in species and less structured, since only dominant and tolerant plant species persisted. Furthermore, limiting trampling appears to have produced positive changes in the dune vegetation assemblage after a period of only two years. These results are encouraging for the management of coastal dune systems. They highlight how a simple and cost-effective management strategy, based on passive recovery conservation measures (i.e., fence building), can be a quick (1-2 years) and effective method for improving and safeguarding the diversity of dune plant communities.

  3. Ethnobotany of dye plants in Dong communities of China.

    Science.gov (United States)

    Liu, Yujing; Ahmed, Selena; Liu, Bo; Guo, Zhiyong; Huang, Weijuan; Wu, Xianjin; Li, Shenghua; Zhou, Jiangju; Lei, Qiyi; Long, Chunlin

    2014-02-19

    Dyes derived from plants have an extensive history of use for coloring food and clothing in Dong communities and other indigenous areas in the uplands of China. In addition to use as coloring agents, Dong communities have historically utilized dye plants for their value for enhancing the nutritive, medicinal and preservative properties of foods. However, the persistence of plant-derived dyes and associated cultural practices and traditional knowledge is threatened with rapid socio-economic change in China. Research is needed to document the ethnobotany of dye plants in indigenous communities towards their conservation and potential commercialization as a sustainable means of supporting local development initiatives. Semi-structured surveys on plants used for coloring agents and associated traditional knowledge were conducted in fifteen Dong villages of Tongdao County in Hunan Province of South Central China during 2011-2012. Transect walks were carried out with key informants identified from semi-structured surveys to collect samples and voucher specimens for each documented plant species for taxonomic identification. Dong households at the study sites utilize the flowers, bark, stems, tubers and roots of 13 plant species from 9 families as dyes to color their customary clothing and food. Out of the documented plants, a total of 7 are used for coloring food, 3 for coloring clothing and 3 for both food and clothing. Documented plants consist of 3 species that yield black pigments, 3 for brownish red/russet pigments, 3 for red pigments, 2 for dark blue pigments and 2 for yellow pigments. In addition to dyes, the plants have multiple uses including medicinal, ornamental, sacrificial, edible, and for timber. The use of dyes derived from plants persists at the study sites for their important role in expressing Dong cultural identity through customary clothing and food. Further research is needed to evaluate the safety of dye plants, their efficacy in enhancing food

  4. Habitat Fragmentation Drives Plant Community Assembly Processes across Life Stages

    Science.gov (United States)

    Hu, Guang; Feeley, Kenneth J.; Yu, Mingjian

    2016-01-01

    Habitat fragmentation is one of the principal causes of biodiversity loss and hence understanding its impacts on community assembly and disassembly is an important topic in ecology. We studied the relationships between fragmentation and community assembly processes in the land-bridge island system of Thousand Island Lake in East China. We focused on the changes in species diversity and phylogenetic diversity that occurred between life stages of woody plants growing on these islands. The observed diversities were compared with the expected diversities from random null models to characterize assembly processes. Regression tree analysis was used to illustrate the relationships between island attributes and community assembly processes. We found that different assembly processes predominate in the seedlings-to-saplings life-stage transition (SS) vs. the saplings-to-trees transition (ST). Island area was the main attribute driving the assembly process in SS. In ST, island isolation was more important. Within a fragmented landscape, the factors driving community assembly processes were found to differ between life stage transitions. Environmental filtering had a strong effect on the seedlings-to-saplings life-stage transition. Habitat isolation and dispersal limitation influenced all plant life stages, but had a weaker effect on communities than area. These findings add to our understanding of the processes driving community assembly and species coexistence in the context of pervasive and widespread habitat loss and fragmentation. PMID:27427960

  5. Community Connections. Time Warner Community Responsibility Report, 1998-2000.

    Science.gov (United States)

    Owens, Jane; Stein, Carol

    This report highlights efforts by Time Warner personnel to strengthen community connections through various programs and services aimed at supporting: education, the arts, volunteerism, diversity, and business-community action. The report is divided into sections focusing on each of these areas. The first section, Education, describes programs…

  6. Plant community resistance to invasion by Bromus species – the roles of community attributes, Bromus Interactions with plant communities, and Bromus traits

    Science.gov (United States)

    Chambers, Jeanne; Germino, Matthew; Belnap, Jayne; Brown, Cynthia; Schupp, Eugene W.; St. Clair, Samuel B

    2016-01-01

    The factors that determine plant community resistance to exotic annual Bromus species (Bromushereafter) are diverse and context specific. They are influenced by the environmental characteristics and attributes of the community, the traits of Bromus species, and the direct and indirect interactions of Bromus with the plant community. Environmental factors, in particular ambient and soil temperatures, have significant effects on the ability of Bromus to establish and spread. Seasonality of precipitation relative to temperature influences plant community resistance toBromus through effects on soil water storage, timing of water and nutrient availability, and dominant plant life forms. Differences among plant communities in how well soil resource use by the plant community matches resource supply rates can influence the magnitude of resource fluctuations due to either climate or disturbance and thus the opportunities for invasion. The spatial and temporal patterns of resource availability and acquisition of growth resources by Bromus versus native species strongly influence resistance to invasion. Traits of Bromus that confer a “priority advantage” for resource use in many communities include early-season germination and high growth and reproductive rates. Resistance to Bromus can be overwhelmed by high propagule supply, low innate seed dormancy, and large, if short-lived, seed banks. Biological crusts can inhibit germination and establishment of invasive annual plants, including several annual Bromus species, but are effective only in the absence of disturbance. Herbivores can have negative direct effects on Bromus, but positive indirect effects through decreases in competitors. Management strategies can be improved through increased understanding of community resistance to exotic annual Bromus species.

  7. [A phylogenetic analysis of plant communities of Teberda Biosphere Reserve].

    Science.gov (United States)

    Shulakov, A A; Egorov, A V; Onipchenko, V G

    2016-01-01

    Phylogenetic analysis of communities is based on the comparison of distances on the phylogenetic tree between species of a community under study and those distances in random samples taken out of local flora. It makes it possible to determine to what extent a community composition is formed by more closely related species (i.e., "clustered") or, on the opposite, it is more even and includes species that are less related with each other. The first case is usually interpreted as a result of strong influence caused by abiotic factors, due to which species with similar ecology, a priori more closely related, would remain: In the second case, biotic factors, such as competition, may come to the fore and lead to forming a community out of distant clades due to divergence of their ecological niches: The aim of this' study Was Ad explore the phylogenetic structure in communities of the northwestern Caucasus at two spatial scales - the scale of area from 4 to 100 m2 and the smaller scale within a community. The list of local flora of the alpine belt has been composed using the database of geobotanic descriptions carried out in Teberda Biosphere Reserve at true altitudes exceeding.1800 m. It includes 585 species of flowering plants belonging to 57 families. Basal groups of flowering plants are.not represented in the list. At the scale of communities of three classes, namely Thlaspietea rotundifolii - commumties formed on screes and pebbles, Calluno-Ulicetea - alpine meadow, and Mulgedio-Aconitetea subalpine meadows, have not demonstrated significant distinction of phylogenetic structure. At intra level, for alpine meadows the larger share of closely related species. (clustered community) is detected. Significantly clustered happen to be those communities developing on rocks (class Asplenietea trichomanis) and alpine (class Juncetea trifidi). At the same time, alpine lichen proved to have even phylogenetic structure at the small scale. Alpine (class Salicetea herbaceae) that

  8. Plant responses to plant growth-promoting rhizobacteria

    NARCIS (Netherlands)

    Loon, L.C. van

    2007-01-01

    Non-pathogenic soilborne microorganisms can promote plant growth, as well as suppress diseases. Plant growth promotion is taken to result from improved nutrient acquisition or hormonal stimulation. Disease suppression can occur through microbial antagonism or induction of resistance in the plant.

  9. Insect herbivory and plant adaptation in an early successional community.

    Science.gov (United States)

    Agrawal, Anurag A; Hastings, Amy P; Fines, Daniel M; Bogdanowicz, Steve; Huber, Meret

    2018-05-01

    To address the role of insect herbivores in adaptation of plant populations and the persistence of selection through succession, we manipulated herbivory in a long-term field experiment. We suppressed insects in half of 16 plots over nine years and examined the genotypic structure and chemical defense of common dandelion (Taraxacum officinale), a naturally colonizing perennial apomictic plant. Insect suppression doubled dandelion abundance in the first few years, but had negligible effects thereafter. Using microsatellite DNA markers, we genotyped >2500 plants and demonstrate that insect suppression altered the genotypic composition of plots in both sampling years. Phenotypic and genotypic estimates of defensive terpenes and phenolics from the field plots allowed us to infer phenotypic plasticity and the response of dandelion populations to insect-mediated natural selection. The effects of insect suppression on plant chemistry were, indeed, driven both by plasticity and plant genotypic identity. In particular, di-phenolic inositol esters were more abundant in plots exposed to herbivory (due to the genotypic composition of the plots) and were also induced in response to herbivory. This field experiment thus demonstrates evolutionary sorting of plant genotypes in response to insect herbivores that was in same direction as the plastic defensive response within genotypes. © 2018 The Author(s). Evolution © 2018 The Society for the Study of Evolution.

  10. Plant Cell Adaptive Responses to Microgravity

    Science.gov (United States)

    Kordyum, Elizabeth; Kozeko, Liudmyla; Talalaev, Alexandr

    simulated microgravity and temperature elevation have different effects on the small HSP genes belonging to subfamilies with different subcellular localization: cytosol/nucleus - PsHSP17.1-CII and PsHSP18.1-CI, cloroplasts - PsHSP26.2-Cl, endoplasmatic reticulum - PsHSP22.7-ER and mitochondria - PsHSP22.9-M: unlike high temperature, clinorotation does not cause denaturation of cell proteins, that confirms the sHSP chaperone function. Dynamics of investigated gene expression in pea seedlings growing 5 days after seed germination under clinorotation was similar to that in the stationary control. Similar patterns in dynamics of sHSP gene expression in the stationary control and under clinorotation may be one of mechanisms providing plant adaptation to simulated microgravity. It is pointed that plant cell responses in microgravity and under clinorotation vary according to growth phase, physiological state, and taxonomic position of the object. At the same time, the responses have, to some degree, a similar character reflecting the changes in cell organelle functional load. Thus, next certain changes in the structure and function of plant cells may be considered as adaptive: 1) an increase in the unsaturated fatty acid content in the plasmalemma, 2) rearrangements of organelle ultrastructure and an increase in their functional load, 3) an increase in cortical F-actin under destabilization of tubulin microtubules, 4) the level of gene expression and synthesis of heat shock proteins, 5) alterations of the enzyme and antioxidant system activity. The dynamics of these patterns demonstrated that the adaptation occurs on the principle of self-regulating systems in the limits of physiological norm reaction. The very importance of changed expression of genes involved in different cellular processes, especially HSP genes, in cell adaptation to altered gravity is discussed.

  11. Community-level plant-soil feedbacks explain landscape distribution of native and non-native plants.

    Science.gov (United States)

    Kulmatiski, Andrew

    2018-02-01

    Plant-soil feedbacks (PSFs) have gained attention for their potential role in explaining plant growth and invasion. While promising, most PSF research has measured plant monoculture growth on different soils in short-term, greenhouse experiments. Here, five soil types were conditioned by growing one native species, three non-native species, or a mixed plant community in different plots in a common-garden experiment. After 4 years, plants were removed and one native and one non-native plant community were planted into replicate plots of each soil type. After three additional years, the percentage cover of each of the three target species in each community was measured. These data were used to parameterize a plant community growth model. Model predictions were compared to native and non-native abundance on the landscape. Native community cover was lowest on soil conditioned by the dominant non-native, Centaurea diffusa , and non-native community cover was lowest on soil cultivated by the dominant native, Pseudoroegneria spicata . Consistent with plant growth on the landscape, the plant growth model predicted that the positive PSFs observed in the common-garden experiment would result in two distinct communities on the landscape: a native plant community on native soils and a non-native plant community on non-native soils. In contrast, when PSF effects were removed, the model predicted that non-native plants would dominate all soils, which was not consistent with plant growth on the landscape. Results provide an example where PSF effects were large enough to change the rank-order abundance of native and non-native plant communities and to explain plant distributions on the landscape. The positive PSFs that contributed to this effect reflected the ability of the two dominant plant species to suppress each other's growth. Results suggest that plant dominance, at least in this system, reflects the ability of a species to suppress the growth of dominant competitors

  12. Diversity of MAPs in some plant communities of Stara Planina

    Directory of Open Access Journals (Sweden)

    Obratov-Petković Dragica

    2006-01-01

    Full Text Available The high floristic diversity of Stara Planina was the starting base for the research of medicinal and aromatic plants (MAPs in individual forest and meadow communities. The sites Javor and Prelesje, forest community Fagetum moesiacae montanum B. Jov. 1953, pioneer community of birch Betuletum verrucosae s.l. and meadow community Agrostietum vulgaris (capillaris Pavlović, Z. 1955, were researched as follows: soil types, floristic composition and structure of the community, percentage of MAPs, as well as the selection of species which, according to the predetermined criteria can be recommended for further exploitation. The study shows that the soil of the forest communities is eutric brown, and meadow soils are dystric and eutric humus-siliceous. The percentage of MAPs in the floristic structure of the study sites in forest and meadow communities is 32.35%. The following species can be recommended for the collection and utilisation: Hypericum perforatum L., Asperula odorata L., Dryopteris filix-mas (L Schott. Urtica dioica L., Euphorbia amygdaloides L., Prunella grandiflora L. Tanacetum vulgare L., Achillea millefolium L., Rumex acetosa L., Campanula glomerata L., Stachys officinalis (L Trevis., Plantago lanceolata W. et K., Potentilla erecta (L Rauchel, Chamaespartium sagittale (L P. Gibbs. Cynanchum vincetoxicum (L Pers., Euphrasia stricta Host., Fagus moesiaca (Matt Liebl. and Fragaria vesca L.

  13. Molecular responses in root-associative rhizospheric bacteria to variations in plant exudates

    Science.gov (United States)

    Abdoun, Hamid; McMillan, Mary; Pereg, Lily

    2015-04-01

    Plant exudates are a major factor in the interface of plant-soil-microbe interactions and it is well documented that the microbial community structure in the rhizosphere is largely influenced by the particular exudates excreted by various plants. Azospirillum brasilense is a plant growth promoting rhizobacterium that is known to interact with a large number of plants, including important food crops. The regulatory gene flcA has an important role in this interaction as it controls morphological differentiation of the bacterium that is essential for attachment to root surfaces. Being a response regulatory gene, flcA mediates the response of the bacterial cell to signals from the surrounding rhizosphere. This makes this regulatory gene a good candidate for analysis of the response of bacteria to rhizospheric alterations, in this case, variations in root exudates. We will report on our studies on the response of Azospirillum, an ecologically, scientifically and agriculturally important bacterial genus, to variations in the rhizosphere.

  14. Herbivory and eutrophication mediate grassland plant nutrient responses across a global climatic gradient

    Science.gov (United States)

    Anderson, T. Michael; Griffith, Daniel M.; Grace, James B.; Lind, Eric M.; Adler, Peter B.; Biederman, Lori A.; Blumenthal, Dana M.; Daleo, Pedro; Firn, Jennifer; Hagenah, Nicole; Harpole, W. Stanley; MacDougall, Andrew S.; McCulley, Rebecca L.; Prober, Suzanne M.; Risch, Anita C.; Sankaran, Mahesh; Schütz, Martin; Seabloom, Eric W.; Stevens, Carly J.; Sullivan, Lauren; Wragg, Peter; Borer, Elizabeth T.

    2018-01-01

    Plant stoichiometry, the relative concentration of elements, is a key regulator of ecosystem functioning and is also being altered by human activities. In this paper we sought to understand the global drivers of plant stoichiometry and compare the relative contribution of climatic vs. anthropogenic effects. We addressed this goal by measuring plant elemental (C, N, P and K) responses to eutrophication and vertebrate herbivore exclusion at eighteen sites on six continents. Across sites, climate and atmospheric N deposition emerged as strong predictors of plot‐level tissue nutrients, mediated by biomass and plant chemistry. Within sites, fertilization increased total plant nutrient pools, but results were contingent on soil fertility and the proportion of grass biomass relative to other functional types. Total plant nutrient pools diverged strongly in response to herbivore exclusion when fertilized; responses were largest in ungrazed plots at low rainfall, whereas herbivore grazing dampened the plant community nutrient responses to fertilization. Our study highlights (1) the importance of climate in determining plant nutrient concentrations mediated through effects on plant biomass, (2) that eutrophication affects grassland nutrient pools via both soil and atmospheric pathways and (3) that interactions among soils, herbivores and eutrophication drive plant nutrient responses at small scales, especially at water‐limited sites.

  15. Water table and species identity outweigh carbon and nitrogen availability in a softwater plant community

    Science.gov (United States)

    Vanderhaeghe, Floris; Smolders, Alfons J. P.; Roelofs, Jan G. M.; Hoffmann, Maurice

    2013-02-01

    Performance of aquatic macrophytes is driven by many environmental factors, and a major challenge is to understand how aquatic macrophyte communities are structured in various environments. In softwater lakes in Western Europe, hydrological state (submersed/emersed), carbon dioxide and ammonium levels and species interactions are considered as driving forces in structuring amphibious plant communities. In this study we aimed at evaluating the relative importance of these factors for four species in a competitive neighbourhood. Softwater lake habitat was simulated during one growing season in laboratory conditions, mimicking water level fluctuation, photoperiod and temperature. Artificial communities consisted of small populations of four softwater macrophyte species: Luronium natans, Baldellia ranunculoides ssp. repens, Eleocharis multicaulis and Hydrocotyle vulgaris. These communities were subjected to two levels of carbon dioxide and ammonium. Additionally, monocultures of Baldellia and Eleocharis were grown at a higher nutrient level combination in order to measure their competitive response in a community. Time (hydrological state) and species identity turned out to be the only consistently significant factors determining community composition. Plant performance was clearly species-dependent, while carbon dioxide and ammonium did not have major effects. The competitive response was significant in both Eleocharis and Baldellia. Competition intensity was highest in the emersed state. Carbon dioxide had a supplementary effect on the within-species performance in Luronium, Baldellia and Eleocharis, with high carbon dioxide level mainly resulting in more flowers and more stolons. Community outcomes and competitive responses in aquatic macrophytes appear difficult to predict, because of mixed life strategies and morphological and functional plasticity. We conclude that hydrological state was the only important environmental factor. The identity of the species that

  16. The role of plant mycorrhizal type and status in modulating the relationship between plant and arbuscular mycorrhizal fungal communities.

    Science.gov (United States)

    Neuenkamp, Lena; Moora, Mari; Öpik, Maarja; Davison, John; Gerz, Maret; Männistö, Minna; Jairus, Teele; Vasar, Martti; Zobel, Martin

    2018-01-25

    Interactions between communities of plants and arbuscular mycorrhizal (AM) fungi shape fundamental ecosystem properties. Experimental evidence suggests that compositional changes in plant and AM fungal communities should be correlated, but empirical data from natural ecosystems are scarce. We investigated the dynamics of covariation between plant and AM fungal communities during three stages of grassland succession, and the biotic and abiotic factors shaping these dynamics. Plant communities were characterised using vegetation surveys. AM fungal communities were characterised by 454-sequencing of the small subunit rRNA gene and identification against the AM fungal reference database MaarjAM. AM fungal abundance was estimated using neutral-lipid fatty acids (NLFAs). Multivariate correlation analysis (Procrustes) revealed a significant relationship between plant and AM fungal community composition. The strength of plant-AM fungal correlation weakened during succession following cessation of grassland management, reflecting changes in the proportion of plants exhibiting different AM status. Plant-AM fungal correlation was strong when the abundance of obligate AM plants was high, and declined as the proportion of facultative AM plants increased. We conclude that the extent to which plants rely on AM symbiosis can determine how tightly communities of plants and AM fungi are interlinked, regulating community assembly of both symbiotic partners. © 2018 The Authors. New Phytologist © 2018 New Phytologist Trust.

  17. Diversity reduces invasibility in experimental plant communities: the role of plant species

    NARCIS (Netherlands)

    Van Ruijven, J.; De Deyn, G.B.; Berendse, F.

    2003-01-01

    Several studies have presented experimental evidence that diversity reduces invasibility in grassland communities. The interpretation of these results has been disputed recently and it was proposed that sampling effects were responsible for the observed decrease of invasibility with diversity. The

  18. Interactions for pollinator visitation and their consequences for reproduction in a plant community

    Science.gov (United States)

    Hegland, Stein Joar; Totland, Ørjan

    2012-08-01

    Competition and facilitation in species interactions attract much attention in ecology, but their relative importance has seldom been evaluated in a community context. We assessed competitive and facilitative interactions for pollinator visitation among co-flowering species in a plant community, investigated the subsequent consequences for plant reproduction, and investigated whether effects could be trait-based. We removed the flowers of two species attractive to pollinators, in two separate experiments and assessed the effects on pollinator visitation rates and components of reproductive success in 11 co-flowering focal herb species. Overall, most focal species appear not to interact with the removal species with respect to pollinator visitation and subsequent reproduction (neutral interactions). Three focal species in the community had significantly higher reproductive responses (fruit production and seed weight) in the presence of the attractive removal species (facilitative interactions), but species interaction effects were less pronounced in species' flower visitation rates. A community-wide meta-analysis demonstrated that the two experiments did not have a significant effect on either facilitation or competition, and that there was no overall correlation between effect sizes for visitation and reproduction. Based on species-specific responses, it seems likely that floral traits such as similar flower colors contribute to interspecific facilitation of pollinator visitation and, in particular, that high pollinator dependence for plant reproduction, and associated pollen limitation, may contribute to subsequent interaction effects on reproduction in the focal species.

  19. Metagenomic analysis of an ecological wastewater treatment plant's microbial communities and their potential to metabolize pharmaceuticals.

    Science.gov (United States)

    Balcom, Ian N; Driscoll, Heather; Vincent, James; Leduc, Meagan

    2016-01-01

    Pharmaceuticals and other micropollutants have been detected in drinking water, groundwater, surface water, and soil around the world. Even in locations where wastewater treatment is required, they can be found in drinking water wells, municipal water supplies, and agricultural soils. It is clear conventional wastewater treatment technologies are not meeting the challenge of the mounting pressures on global freshwater supplies. Cost-effective ecological wastewater treatment technologies have been developed in response. To determine whether the removal of micropollutants in ecological wastewater treatment plants (WWTPs) is promoted by the plant-microbe interactions, as has been reported for other recalcitrant xenobiotics, biofilm microbial communities growing on the surfaces of plant roots were profiled by whole metagenome sequencing and compared to the microbial communities residing in the wastewater. In this study, the concentrations of pharmaceuticals and personal care products (PPCPs) were quantified in each treatment tank of the ecological WWTP treating human wastewater at a highway rest stop and visitor center in Vermont. The concentrations of detected PPCPs were substantially greater than values reported for conventional WWTPs likely due to onsite recirculation of wastewater. The greatest reductions in PPCPs concentrations were observed in the anoxic treatment tank where Bacilli dominated the biofilm community. Benzoate degradation was the most abundant xenobiotic metabolic category identified throughout the system. Collectively, the microbial communities residing in the wastewater were taxonomically and metabolically more diverse than the immersed plant root biofilm. However, greater heterogeneity and higher relative abundances of xenobiotic metabolism genes was observed for the root biofilm.

  20. Mapping of aggregated floodplain plant communities using image fusion of CASI and LiDAR data

    NARCIS (Netherlands)

    Verrelst, J.; Geerling, G.W.; Sykora, K.V.; Clevers, J.G.P.W.

    2009-01-01

    Combined optical and laser altimeter data offer the potential to map and monitor plant communities based on their spectral and structural characteristics. A problem unresolved is, however, that narrowly defined plant communities, i.e. plant communities at a low hierarchical level of classification

  1. Evolutionary History Underlies Plant Physiological Responses to Global Change Since the Last Glacial Maximum

    Science.gov (United States)

    Becklin, K. M.; Medeiros, J. S.; Sale, K. R.; Ward, J. K.

    2014-12-01

    Assessing family and species-level variation in physiological responses to global change across geologic time is critical for understanding factors that underlie changes in species distributions and community composition. Ancient plant specimens preserved within packrat middens are invaluable in this context since they allow for comparisons between co-occurring plant lineages. Here we used modern and ancient plant specimens preserved within packrat middens from the Snake Range, NV to investigate the physiological responses of a mixed montane conifer community to global change since the last glacial maximum. We used a conceptual model to infer relative changes in stomatal conductance and maximum photosynthetic capacity from measures of leaf carbon isotopes, stomatal characteristics, and leaf nitrogen content. Our results indicate that most of the sampled taxa decreased stomatal conductance and/or photosynthetic capacity from glacial to modern times. However, plant families differed in the timing and magnitude of these physiological responses. Additionally, leaf-level responses were more similar within plant families than within co-occurring species assemblages. This suggests that adaptation at the level of leaf physiology may not be the main determinant of shifts in community composition, and that plant evolutionary history may drive physiological adaptation to global change over recent geologic time.

  2. Plant responses to variable timing of aboveground clipping and belowground herbivory depend on plant age

    NARCIS (Netherlands)

    Wang, Minggang; Bezemer, T. Martijn; van der Putten, W.H.; Brinkman, Pella; Biere, Arjen

    2017-01-01

    Aims Plants use different types of responses such as tolerance and induced defense to mitigate the effects of herbivores. The direction and magnitude of both these plant responses can vary with plant age. However, most studies have focused on aboveground herbivory, whereas important feeding occurs

  3. Community responses to extreme climatic conditions

    Directory of Open Access Journals (Sweden)

    Frédéric JIGUET, Lluis BROTONS, Vincent DEVICTOR

    2011-06-01

    Full Text Available Species assemblages and natural communities are increasingly impacted by changes in the frequency and severity of extreme climatic events. Here we propose a brief overview of expected and demonstrated direct and indirect impacts of extreme events on animal communities. We show that differential impacts on basic biological parameters of individual species can lead to strong changes in community composition and structure with the potential to considerably modify the functional traits of the community. Sudden disequilibria have even been shown to induce irreversible shifts in marine ecosystems, while cascade effects on various taxonomic groups have been highlighted in Mediterranean forests. Indirect effects of extreme climatic events are expected when event-induced habitat changes (e.g. soil stability, vegetation composition, water flows altered by droughts, floods or hurricanes have differential consequences on species assembled within the communities. Moreover, in increasing the amplitude of trophic mismatches, extreme events are likely to turn many systems into ecological traps under climate change. Finally, we propose a focus on the potential impacts of an extreme heat wave on local assemblages as an empirical case study, analysing monitoring data on breeding birds collected in France. In this example, we show that despite specific populations were differently affected by local temperature anomalies, communities seem to be unaffected by a sudden heat wave. These results suggest that communities are tracking climate change at the highest possible rate [Current Zoology 57 (3: 406–413, 2011].

  4. Development of an improved compact package plant for small community waste-water treatment

    CSIR Research Space (South Africa)

    Hulsman, A

    1993-01-01

    Full Text Available The challenges facing the design and operation of small community wastewater treatment plants are discussed. The package plant concept is considered and the consequent development of a compact intermittently aerated activated sludge package plant...

  5. Bird community responses to the edge between suburbs and reserves.

    Science.gov (United States)

    Ikin, Karen; Barton, Philip S; Knight, Emma; Lindenmayer, David B; Fischer, Joern; Manning, Adrian D

    2014-02-01

    New insights into community-level responses at the urban fringe, and the mechanisms underlying them, are needed. In our study, we investigated the compositional distinctiveness and variability of a breeding bird community at both sides of established edges between suburban residential areas and woodland reserves in Canberra, Australia. Our goals were to determine if: (1) community-level responses were direct (differed with distance from the edge, independent of vegetation) or indirect (differed in response to edge-related changes in vegetation), and (2) if guild-level responses provided the mechanism underpinning community-level responses. We found that suburbs and reserves supported significantly distinct bird communities. The suburban bird community, characterised by urban-adapted native and exotic species, had a weak direct edge response, with decreasing compositional variability with distance from the edge. In comparison, the reserve bird community, characterised by woodland-dependent species, was related to local tree and shrub cover. This was not an indirect response, however, as tree and shrub cover was not related to edge distance. We found that the relative richness of nesting, foraging and body size guilds also displayed similar edge responses, indicating that they underpinned the observed community-level responses. Our study illustrates how community-level responses provide valuable insights into how communities respond to differences in resources between two contrasting habitats. Further, the effects of the suburban matrix penetrate into reserves for greater distances than previously thought. Suburbs and adjacent reserves, however, provided important habitat resources for many native species and the conservation of these areas should not be discounted from continued management strategies.

  6. Ecological surveys of certain plant communities around urban areas ...

    African Journals Online (AJOL)

    It was also observed that certain edaphic and human activity, discharge of pollutants with out any pretreatment was found responsible for variation in the nature, structure and composition of vegetation. The plant growth and their continuity was in danger in many disturb areas, especially in some coastal areas where salinity ...

  7. Soil fungal community responses to global changes

    DEFF Research Database (Denmark)

    Haugwitz, Merian Skouw

    Global change will affect the functioning and structure of terrestrial ecosystems and since soil fungi are key players in organic matter decomposition and nutrient turnover, shifts in fungal community composition might have a strong impact on soil functioning. The main focus of this thesis...... was therefore to investigate the impact of global environmental changes on soil fungal communities in a temperate and subartic heath ecosystem. The objective was further to determine global change effects on major functional groups of fungi and analyze the influence of fungal community changes on soil carbon...... and nutrient availability and storage. By combining molecular methods such as 454 pyrosequencing and quantitative PCR of fungal ITS amplicons with analyses of soil enzymes, nutrient pools of carbon, nitrogen and phosphorus we were able to characterize soil fungal communities as well as their impact on nutrient...

  8. Exclusion, Violence, and Community Responses in Central ...

    International Development Research Centre (IDRC) Digital Library (Canada)

    Personal

    2015-05-13

    May 13, 2015 ... similar conditions of social exclusion, different levels of violence can be explained because communities capacities to face violence. • Methodology: ... in El Salvador. • Mix of quantitative and qualitative techniques of research.

  9. Plant responses to precipitation in desert ecosystems: integrating functional types, pulses, thresholds, and delays.

    Science.gov (United States)

    Ogle, Kiona; Reynolds, James F

    2004-10-01

    The 'two-layer' and 'pulse-reserve' hypotheses were developed 30 years ago and continue to serve as the standard for many experiments and modeling studies that examine relationships between primary productivity and rainfall variability in aridlands. The two-layer hypothesis considers two important plant functional types (FTs) and predicts that woody and herbaceous plants are able to co-exist in savannas because they utilize water from different soil layers (or depths). The pulse-reserve model addresses the response of individual plants to precipitation and predicts that there are 'biologically important' rain events that stimulate plant growth and reproduction. These pulses of precipitation may play a key role in long-term plant function and survival (as compared to seasonal or annual rainfall totals as per the two-layer model). In this paper, we re-evaluate these paradigms in terms of their generality, strengths, and limitations. We suggest that while seasonality and resource partitioning (key to the two-layer model) and biologically important precipitation events (key to the pulse-reserve model) are critical to understanding plant responses to precipitation in aridlands, both paradigms have significant limitations. Neither account for plasticity in rooting habits of woody plants, potential delayed responses of plants to rainfall, explicit precipitation thresholds, or vagaries in plant phenology. To address these limitations, we integrate the ideas of precipitation thresholds and plant delays, resource partitioning, and plant FT strategies into a simple 'threshold-delay' model. The model contains six basic parameters that capture the nonlinear nature of plant responses to pulse precipitation. We review the literature within the context of our threshold-delay model to: (i) develop testable hypotheses about how different plant FTs respond to pulses; (ii) identify weaknesses in the current state-of-knowledge; and (iii) suggest future research directions that will

  10. Annual glyphosate treatments alter growth of unaffected bentgrass (Agrostis weeds and plant community composition.

    Directory of Open Access Journals (Sweden)

    Collin W Ahrens

    Full Text Available Herbicide resistance is becoming more common in weed ecotypes and crop species including turfgrasses, but current gaps in knowledge limit predictive ecological risk assessments and risk management plans. This project examined the effect of annual glyphosate applications on the vegetative growth and reproductive potential of two weedy bentgrasses, creeping bentgrass (CB and redtop (RT, where the glyphosate resistance (GR trait was mimicked by covering the bentgrass plants during glyphosate application. Five field plots were studied in habitats commonly inhabited by weedy bentgrasses including an agricultural hayfield, natural meadow, and wasteland. Results showed that annual glyphosate treatment improved bentgrass survivorship, vegetative growth, and reproductive potential compared with bentgrass in unsprayed subplots. In the second year of growth, RT plants had an 86-fold increase in flower number in glyphosate-treated subplots versus controls, while CB plants had a 20-fold increase. At the end of the three year study, plant community composition had changed in glyphosate-treated subplots in hayfield and meadow plots compared to controls. Soils in subplots receiving glyphosate had higher nitrate concentrations than controls. This is the first study to mimic the GR trait in bentgrass plants with the goal of quantifying bentgrass response to glyphosate selection pressure and understanding the impacts on surrounding plant communities.

  11. The impact of plant chemical diversity on plant-herbivore interactions at the community level.

    Science.gov (United States)

    Salazar, Diego; Jaramillo, Alejandra; Marquis, Robert J

    2016-08-01

    Understanding the role of diversity in ecosystem processes and species interactions is a central goal of ecology. For plant-herbivore interactions, it has been hypothesized that when plant species diversity is reduced, loss of plant biomass to herbivores increases. Although long-standing, this hypothesis has received mixed support. Increasing plant chemical diversity with increasing plant taxonomic diversity is likely to be important for plant-herbivore interactions at the community level, but the role of chemical diversity is unexplored. Here we assess the effect of volatile chemical diversity on patterns of herbivore damage in naturally occurring patches of Piper (Piperaceae) shrubs in a Costa Rican lowland wet forest. Volatile chemical diversity negatively affected total, specialist, and generalist herbivore damage. Furthermore, there were differences between the effects of high-volatility and low-volatility chemical diversity on herbivore damage. High-volatility diversity reduced specialist herbivory, while low-volatility diversity reduced generalist herbivory. Our data suggest that, although increased plant diversity is expected to reduce average herbivore damage, this pattern is likely mediated by the diversity of defensive compounds and general classes of anti-herbivore traits, as well as the degree of specialization of the herbivores attacking those plants.

  12. Abandoned floodplain plant communities along a regulated dryland river

    Science.gov (United States)

    Reynolds, L. V.; Shafroth, Patrick B.; House, P. K.

    2014-01-01

    Rivers and their floodplains worldwide have changed dramatically over the last century because of regulation by dams, flow diversions and channel stabilization. Floodplains no longer inundated by river flows following dam-induced flood reduction comprise large areas of bottomland habitat, but the effects of abandonment on plant communities are not well understood. Using a hydraulic flow model, geomorphic mapping and field surveys, we addressed the following questions along the Bill Williams River, Arizona: (i) What per cent of the bottomland do abandoned floodplains comprise? and (ii) Are abandoned floodplains quantitatively different from adjacent xeric and riparian surfaces in terms of vegetation composition and surface sediment? We found that nearly 70% of active channel and floodplain area was abandoned following dam installation. Abandoned floodplains along the Bill Williams River tend to be similar to each other yet distinct from neighbouring habitats: they have been altered physically from their historic state, leading to distinct combinations of surface sediments, hydrology and plant communities. Abandoned floodplains may transition to xeric communities over time but are likely to retain some riparian qualities as long as there is access to relatively shallow ground water. With expected increases in water demand and drying climatic conditions in many regions, these surfaces and associated vegetation will continue to be extensive in riparian landscapes worldwide

  13. Agroecology: Implications for plant response to climate change

    Science.gov (United States)

    Agricultural ecosystems (agroecosystems) represent the balance between the physiological responses of plants and plant canopies and the energy exchanges. Rising temperature and increasing CO2 coupled with an increase in variability of precipitation will create a complex set of interactions on plant ...

  14. Pivoting from Arabidopsis to wheat to understand how agricultural plants integrate responses to biotic stress

    Science.gov (United States)

    Here we argue for a research initiative on gene-for-gene (g-f-g) interactions between wheat and its parasites. One aim is to begin a conversation between the disparate communities of plant pathology and entomology. Another is to understand how responses to biotic stress are integrated in an import...

  15. Bacterial endophyte communities of three agricultural important grass species differ in their response towards management regimes

    Science.gov (United States)

    Wemheuer, Franziska; Kaiser, Kristin; Karlovsky, Petr; Daniel, Rolf; Vidal, Stefan; Wemheuer, Bernd

    2017-01-01

    Endophytic bacteria are critical for plant growth and health. However, compositional and functional responses of bacterial endophyte communities towards agricultural practices are still poorly understood. Hence, we analyzed the influence of fertilizer application and mowing frequency on bacterial endophytes in three agriculturally important grass species. For this purpose, we examined bacterial endophytic communities in aerial plant parts of Dactylis glomerata L., Festuca rubra L., and Lolium perenne L. by pyrotag sequencing of bacterial 16S rRNA genes over two consecutive years. Although management regimes influenced endophyte communities, observed responses were grass species-specific. This might be attributed to several bacteria specifically associated with a single grass species. We further predicted functional profiles from obtained 16S rRNA data. These profiles revealed that predicted abundances of genes involved in plant growth promotion or nitrogen metabolism differed between grass species and between management regimes. Moreover, structural and functional community patterns showed no correlation to each other indicating that plant species-specific selection of endophytes is driven by functional rather than phylogenetic traits. The unique combination of 16S rRNA data and functional profiles provided a holistic picture of compositional and functional responses of bacterial endophytes in agricultural relevant grass species towards management practices.

  16. Do competitors modulate rare plant response to precipitation change?

    Science.gov (United States)

    Levine, J.M.; Kathryn, Mceachern A.; Cowan, C.

    2010-01-01

    Ecologists increasingly suspect that climate change will directly impact species physiology, demography, and phenology, but also indirectly affect these measures via changes to the surrounding community. Unfortunately, few studies examine both the direct and indirect pathways of impact. Doing so is important because altered competitive pressures can reduce or magnify the direct responses of a focal species to climate change. Here, we examine the effects of changing rainfall on three rare annual plant species in the presence and absence of competition on the California Channel Islands. We used rain-out shelters and hand watering to exclude and augment early, late, and season-long rainfall, spanning the wide range of precipitation change forecast for the region. In the absence of competition, droughts reduced the population growth rates of two of three focal annuals, while increased rainfall was only sometimes beneficial, As compared to the focal species, the dominant competitors were more sensitive to the precipitation treatments, benefiting from increased season-long precipitation and harmed by droughts. Importantly, the response of two of three competitors to the precipitation treatments tended to be positively correlated with those of the focal annuals. Although this leads to the expectation that increased competition will counter the direct benefits of favorable conditions, such indirect effects of precipitation change proved weak to nonexistent in our experiment. Competitors had little influence on the precipitation response of two focal species, due to their low sensitivity to competition and highly variable precipitation responses. Competition did affect how our third focal species responded to precipitation change, but this effect only approached significance, and whether it truly resulted from competitor response to precipitation change was unclear. Our work suggests that even when competitors respond to climate change, these responses may have little

  17. Agrobacterium tumefaciens responses to plant-derived signaling molecules

    Science.gov (United States)

    Subramoni, Sujatha; Nathoo, Naeem; Klimov, Eugene; Yuan, Ze-Chun

    2014-01-01

    As a special phytopathogen, Agrobacterium tumefaciens infects a wide range of plant hosts and causes plant tumors also known as crown galls. The complexity of Agrobacterium–plant interaction has been studied for several decades. Agrobacterium pathogenicity is largely attributed to its evolved capabilities of precise recognition and response to plant-derived chemical signals. Agrobacterium perceives plant-derived signals to activate its virulence genes, which are responsible for transferring and integrating its Transferred DNA (T-DNA) from its Tumor-inducing (Ti) plasmid into the plant nucleus. The expression of T-DNA in plant hosts leads to the production of a large amount of indole-3-acetic acid (IAA), cytokinin (CK), and opines. IAA and CK stimulate plant growth, resulting in tumor formation. Agrobacterium utilizes opines as nutrient sources as well as signals in order to activate its quorum sensing (QS) to further promote virulence and opine metabolism. Intriguingly, Agrobacterium also recognizes plant-derived signals including γ-amino butyric acid and salicylic acid (SA) to activate quorum quenching that reduces the level of QS signals, thereby avoiding the elicitation of plant defense and preserving energy. In addition, Agrobacterium hijacks plant-derived signals including SA, IAA, and ethylene to down-regulate its virulence genes located on the Ti plasmid. Moreover, certain metabolites from corn (Zea mays) also inhibit the expression of Agrobacterium virulence genes. Here we outline the responses of Agrobacterium to major plant-derived signals that impact Agrobacterium–plant interactions. PMID:25071805

  18. Agrobacterium tumefaciens responses to plant-derived signaling molecules

    Directory of Open Access Journals (Sweden)

    Sujatha eSubramoni

    2014-07-01

    Full Text Available As a special phytopathogen, Agrobacterium tumefaciens infects a wide range of plant hosts and causes plant tumors also known as crown galls. The complexity of Agrobacterium-plant interaction has been studied for several decades. Agrobacterium pathogenicity is largely attributed to its evolved capabilities of precise recognition and response to plant-derived chemical signals. Agrobacterium perceives plant-derived signals to activate its virulence genes, which are responsible for transferring and integrating its T-DNA (Transferred DNA from its Tumour-inducing (Ti plasmid into the plant nucleus. The expression of T-DNA in plant hosts leads to the production of a large amount of indole-3-acetic acid (IAA, cytokinin (CK and opines. IAA and CK stimulate plant growth, resulting in tumor formation. Agrobacterium utilizes opines as nutrient sources as well as signals in order to activate its quorum sensing (QS to further promote virulence and opine metabolism. Intriguingly, Agrobacterium also recognizes plant-derived signals including -amino butyric acid (GABA and salicylic acid (SA to activate quorum quenching that reduces the level of QS signals, thereby avoiding the elicitation of plant defense and preserving energy. In addition, Agrobacterium hijacks plant-derived signals including SA, IAA, and ethylene (ET to down-regulate its virulence genes located on the Ti plasmid. Moreover, certain metabolites from corn (Zea mays also inhibit the expression of Agrobacterium virulence genes. Here we outline the responses of Agrobacterium to major plant-derived signals that impact Agrobacterium-plant interactions.

  19. Evolutionary responses of native plant species to invasive plants: a review.

    Science.gov (United States)

    Oduor, Ayub M O

    2013-12-01

    Strong competition from invasive plant species often leads to declines in abundances and may, in certain cases, cause localized extinctions of native plant species. Nevertheless, studies have shown that certain populations of native plant species can co-exist with invasive plant species,suggesting the possibility of adaptive evolutionary responses of those populations to the invasive plants. Empirical inference of evolutionary responses of the native plant species to invasive plants has involved experiments comparing two conspecific groups of native plants for differences in expression of growth/reproductive traits: populations that have experienced competition from the invasive plant species (i.e. experienced natives) versus populations with no known history of interactions with the invasive plant species (i.e. naıve natives). Here, I employ a meta-analysis to obtain a general pattern of inferred evolutionary responses of native plant species from 53 such studies. In general, the experienced natives had significantly higher growth/reproductive performances than naıve natives, when grown with or without competition from invasive plants.While the current results indicate that certain populations of native plant species could potentially adapt evolutionarily to invasive plant species, the ecological and evolutionary mechanisms that probably underlie such evolutionary responses remain unexplored and should be the focus of future studies.

  20. Emergency response training with the BNL plant analyzer

    International Nuclear Information System (INIS)

    Cheng, H.S.; Guppy, J.G.; Mallen, A.N.; Wulff, W.

    1987-01-01

    Presented is the experience in the use of the BNL Plant Analyzer for NRC emergency response training to simulated accidents in a BWR. The unique features of the BNL Plant Analyzer that are important for the emergency response training are summarized. A closed-loop simulation of all the key systems of a power plant in question was found essential to the realism of the emergency drills conducted at NRC. The faster than real-time simulation speeds afforded by the BNL Plant Analyzer have demonstrated its usefulness for the timely conduct of the emergency response training

  1. Physiological response of soybean genotypes to plant density

    NARCIS (Netherlands)

    Gan, Y; Stulen, [No Value; van Keulen, H; Kuiper, PJC

    2002-01-01

    Response of soybean (Glycine max (L.) Merr.) to plant density has occupied a segment of agronomic research for most of the century. Genotype differences have been noted especially in response to planting date, lodging problems and water limitation. There is limited information on the physiological

  2. Responses of potatoes plants inoculated with arbuscular ...

    African Journals Online (AJOL)

    A pot experiment was set to examine the impact of the foliar litter (Hardwickia binata and Azadirachta indica) and an arbuscular mycorrhizal (AM) fungus on the development of two varieties of potato plants (Aida, Atlas). Three litter doses (0, 25 and 50 g) were applied to the pots after bedding plantlets. The plants were ...

  3. Development programmes in rural communities affected by industrial sites. The case of nuclear plants in Spain

    International Nuclear Information System (INIS)

    Yuncal, A.

    2000-01-01

    A socioeconomic analysis performed for rural communities affected by industrial sites, namely for the case of nuclear power plants in Spain a common proposal for all the European countries is made. Existence of a common European program that could cover the following aspects: Creation of a Committee to enhance the participation in decision making process on different aspects, information policies, security, transport, waste management, investments, economic development; Contract between local authorities, State and companies responsibilities and financing; Legal framework of political organization; common socio-economic program including environment, employment, companies activities, responsibilities, taxes

  4. Priming of antiherbivore defensive responses in plants

    Institute of Scientific and Technical Information of China (English)

    Jinwon Kim; Gary W.Felton

    2013-01-01

    Defense priming is defined as increased readiness of defense induction.A growing body of literature indicates that plants (or intact parts of a plant) are primed in anticipation of impending environmental stresses,both biotic and abiotic,and upon the following stimulus,induce defenses more quickly and strongly.For instance,some plants previously exposed to herbivore-inducible plant volatiles (HIPVs) from neighboring plants under herbivore attack show faster or stronger defense activation and enhanced insect resistance when challenged with secondary insect feeding.Research on priming of antiherbivore defense has been limited to the HIPV-mediated mechanism until recently,but significant advances were made in the past three years,including non-HIPV-mediated defense priming,epigenetic modifications as the molecular mechanism of priming,and others.It is timely to consider the advances in research on defense priming in the plantinsect interactions.

  5. Population and community ecology of the rare plant amsinckia grandiflora

    Energy Technology Data Exchange (ETDEWEB)

    Carlsen, T.M.

    1996-11-01

    Research was conducted between the fall of 1992 and the spring on the population and community ecology of the rare annual plant, Amsinckia glandiflora (Gray) Kleeb. ex Greene (Boraginaceae). The research goal was to investigate the causes of the species rarity, data useful to restorative efforts. The work focused on the examination of competitive suppression by exotic annual grasses; comparisons with common, weedy congener; and the role of litter cover and seed germination and seedling establishment. Annual exotic grasses reduced A. grandiflora reproductive output to a greater extent than did the native perennial bunch grass.

  6. A review of major factors influencing plant responses to recreation impacts

    Science.gov (United States)

    Kuss, Fred R.

    1986-09-01

    This article reviews some of the more important factors found to influence the susceptibility of plants to trampling impacts associated with recreational use of natural areas. A three-way interaction mediates plant responses to impacts: plant x environment x stress level(s). Plant responses vary in part according to the genetic constitution of the plant, life and growth form, the adaptive flexibility of the plant, and anatomical differences inherent to growth habit and morphology. Other factors that influence plant sensitivities to impacts are the habitat environments in which plants grow, since a number of conditions such as moisture excesses or deficiencies, nitrogen or oxygen starvation, late frosts, etc., cause physiological injury and may increase plant sensitivity to impacts. Among the environmental factors that may increase or lessen plant sensitivities to impacts are soil moisture levels, canopy density, elevation, aspect, microclimate, soil drainage, texture, fertility and productivity. Seasonal influences also bear consideration since environmental changes and phonological and physiological events are mediated by time of year. Stresses are caused by both direct and indirect forms of impact and vary according to season of use, frequency and amount of use, and the type of activity. These interactions are further complicated by evidence that inter- and intraspecific competition, antagonism, and commensalism may influence differences in the sensitivity of plant communities to impacts.

  7. 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

  8. Plant response to nutrient availability across variable bedrock geologies

    Science.gov (United States)

    Castle, S.C.; Neff, J.C.

    2009-01-01

    We investigated the role of rock-derived mineral nutrient availability on the nutrient dynamics of overlying forest communities (Populus tremuloides and Picea engelmanni-Abies lasiocarpa v. arizonica) across three parent materials (andesite, limestone, and sandstone) in the southern Rocky Mountains of Colorado. Broad geochemical differences were observed between bedrock materials; however, bulk soil chemistries were remarkably similar between the three different sites. In contrast, soil nutrient pools were considerably different, particularly for P, Ca, and Mg concentrations. Despite variations in nutrient stocks and nutrient availability in soils, we observed relatively inflexible foliar concentrations and foliar stoichiometries for both deciduous and coniferous species. Foliar nutrient resorption (P and K) in the deciduous species followed patterns of nutrient content across substrate types, with higher resorption corresponding to lower bedrock concentrations. Work presented here indicates a complex plant response to available soil nutrients, wherein plant nutrient use compensates for variations in supply gradients and results in the maintenance of a narrow range in foliar stoichiometry. ?? 2008 Springer Science+Business Media, LLC.

  9. Plant response to biotic stress: Is there a common epigenetic response during plant-pathogenic and symbiotic interactions?

    Science.gov (United States)

    Zogli, Prince; Libault, Marc

    2017-10-01

    Plants constantly interact with pathogenic and symbiotic microorganisms. Recent studies have revealed several regulatory mechanisms controlling these interactions. Among them, the plant defense system is activated not only in response to pathogenic, but also in response to symbiotic microbes. Interestingly, shortly after symbiotic microbial recognition, the plant defense system is suppressed to promote plant infection by symbionts. Research studies have demonstrated the influence of the plant epigenome in modulating both pathogenic and symbiotic plant-microbe interactions, thereby influencing plant survival, adaptation and evolution of the plant response to microbial infections. It is however unclear if plant pathogenic and symbiotic responses share similar epigenomic profiles or if epigenomic changes differentially regulate plant-microbe symbiosis and pathogenesis. In this mini-review, we provide an update of the current knowledge of epigenomic control on plant immune responses and symbiosis, with a special attention being paid to knowledge gap and potential strategies to fill-in the missing links. Copyright © 2017 Elsevier B.V. All rights reserved.

  10. Subtle variation in shade avoidance responses may have profound consequences for plant competitiveness.

    Science.gov (United States)

    Bongers, Franca J; Pierik, Ronald; Anten, Niels P R; Evers, Jochem B

    2017-12-21

    Although phenotypic plasticity has been shown to be beneficial for plant competitiveness for light, there is limited knowledge on how variation in these plastic responses plays a role in determining competitiveness. A combination of detailed plant experiments and functional-structural plant (FSP) modelling was used that captures the complex dynamic feedback between the changing plant phenotype and the within-canopy light environment in time and 3-D space. Leaf angle increase (hyponasty) and changes in petiole elongation rates in response to changes in the ratio between red and far-red light, two important shade avoidance responses in Arabidopsis thaliana growing in dense population stands, were chosen as a case study for plant plasticity. Measuring and implementing these responses into an FSP model allowed simulation of plant phenotype as an emergent property of the underlying growth and response mechanisms. Both the experimental and model results showed that substantial differences in competitiveness may arise between genotypes with only marginally different hyponasty or petiole elongation responses, due to the amplification of plant growth differences by small changes in plant phenotype. In addition, this study illustrated that strong competitive responses do not necessarily have to result in a tragedy of the commons; success in competition at the expense of community performance. Together, these findings indicate that selection pressure could probably have played a role in fine-tuning the sensitive shade avoidance responses found in plants. The model approach presented here provides a novel tool to analyse further how natural selection could have acted on the evolution of plastic responses.

  11. Culturally Responsive Leadership for Community Empowerment

    Science.gov (United States)

    Johnson, Lauri

    2014-01-01

    Culturally responsive leadership, derived from the concept of culturally responsive pedagogy, incorporates those leadership philosophies, practices, and policies that create inclusive schooling environments for students and families from ethnically and culturally diverse backgrounds. In this essay I extend the tenets of culturally responsive…

  12. Responsibility and Generativity in Online Learning Communities

    Science.gov (United States)

    Beth, Alicia D.; Jordan, Michelle E.; Schallert, Diane L.; Reed, JoyLynn H.; Kim, Minseong

    2015-01-01

    The purpose of this study was to investigate whether and how students enact "responsibility" and "generativity" through their comments in asynchronous online discussions. "Responsibility" referred to discourse markers indicating participants' sense that their contributions are required in order to uphold their…

  13. Impacts of extreme winter warming events on plant physiology in a sub-Arctic heath community.

    Science.gov (United States)

    Bokhorst, Stef; Bjerke, Jarle W; Davey, Matthew P; Taulavuori, Kari; Taulavuori, Erja; Laine, Kari; Callaghan, Terry V; Phoenix, Gareth K

    2010-10-01

    Insulation provided by snow cover and tolerance of freezing by physiological acclimation allows Arctic plants to survive cold winter temperatures. However, both the protection mechanisms may be lost with winter climate change, especially during extreme winter warming events where loss of snow cover from snow melt results in exposure of plants to warm temperatures and then returning extreme cold in the absence of insulating snow. These events cause considerable damage to Arctic plants, but physiological responses behind such damage remain unknown. Here, we report simulations of extreme winter warming events using infrared heating lamps and soil warming cables in a sub-Arctic heathland. During these events, we measured maximum quantum yield of photosystem II (PSII), photosynthesis, respiration, bud swelling and associated bud carbohydrate changes and lipid peroxidation to identify physiological responses during and after the winter warming events in three dwarf shrub species: Empetrum hermaphroditum, Vaccinium vitis-idaea and Vaccinium myrtillus. Winter warming increased maximum quantum yield of PSII, and photosynthesis was initiated for E. hermaphroditum and V. vitis-idaea. Bud swelling, bud carbohydrate decreases and lipid peroxidation were largest for E. hermaphroditum, whereas V. myrtillus and V. vitis-idaea showed no or less strong responses. Increased physiological activity and bud swelling suggest that sub-Arctic plants can initiate spring-like development in response to a short winter warming event. Lipid peroxidation suggests that plants experience increased winter stress. The observed differences between species in physiological responses are broadly consistent with interspecific differences in damage seen in previous studies, with E. hermaphroditum and V. myrtillus tending to be most sensitive. This suggests that initiation of spring-like development may be a major driver in the damage caused by winter warming events that are predicted to become more

  14. University-Community Engagement: Case Study of University Social Responsibility

    Science.gov (United States)

    Chile, Love M.; Black, Xavier M.

    2015-01-01

    Corporatisation of universities has drawn parallels between contemporary universities and business corporations, and extended analysis of corporate social responsibility to universities. This article reports on a case study of university-community engagement with schools and school communities through youth engagement programmes to enhance…

  15. Experience with RTD response time testing in nuclear power plants

    International Nuclear Information System (INIS)

    Hashemian, H.M.; Kerlin, T.W.

    1985-01-01

    The reactor coolant temperatures in pressurized water reactors are measured with platinum resistance temperature detectors (RTDs). The information furnished by these RTDs is used for plant protection as well as control. As a part of the plant protection system, the RTDs must respond to temperature changes in a timely fashion. The RTD response time requirements are different for the various plant types. These requirements are specified in the plant technical specifications in terms of an RTd time constant. The current time constant requirements for nuclear plant RTDs varies from 0.5 seconds to 13.0 seconds depending on the type of the plant. Therefore, different types of RTDs are used in different plants to achieve the required time constants. In addition, in-situ response time tests are periodically performed on protective system RTDs to ensure that the in-service time constants are within acceptable limits as the plant is operating. The periodic testing is important because response time degradation may occur while the RTD ages in the process. Recent response time tests in operating plants revealed unacceptable time constants for several protection system RTDs. As a result, these plants had to be shut down to resolve the problem which in one case was due to improper installation and in another case was because of degradation of a thermal compound used in the thermowell

  16. Plant Community Richness Mediates Inhibitory Interactions and Resource Competition between Streptomyces and Fusarium Populations in the Rhizosphere.

    Science.gov (United States)

    Essarioui, Adil; LeBlanc, Nicholas; Kistler, Harold C; Kinkel, Linda L

    2017-07-01

    Plant community characteristics impact rhizosphere Streptomyces nutrient competition and antagonistic capacities. However, the effects of Streptomyces on, and their responses to, coexisting microorganisms as a function of plant host or plant species richness have received little attention. In this work, we characterized antagonistic activities and nutrient use among Streptomyces and Fusarium from the rhizosphere of Andropogon gerardii (Ag) and Lespedeza capitata (Lc) plants growing in communities of 1 (monoculture) or 16 (polyculture) plant species. Streptomyces from monoculture were more antagonistic against Fusarium than those from polyculture. In contrast, Fusarium isolates from polyculture had greater inhibitory capacities against Streptomyces than isolates from monoculture. Although Fusarium isolates had on average greater niche widths, the collection of Streptomyces isolates in total used a greater diversity of nutrients for growth. Plant richness, but not plant host, influenced the potential for resource competition between the two taxa. Fusarium isolates had greater niche overlap with Streptomyces in monoculture than polyculture, suggesting greater potential for Fusarium to competitively challenge Streptomyces in monoculture plant communities. In contrast, Streptomyces had greater niche overlap with Fusarium in polyculture than monoculture, suggesting that Fusarium experiences greater resource competition with Streptomyces in polyculture than monoculture. These patterns of competitive and inhibitory phenotypes among Streptomyces and Fusarium populations are consistent with selection for Fusarium-antagonistic Streptomyces populations in the presence of strong Fusarium resource competition in plant monocultures. Similarly, these results suggest selection for Streptomyces-inhibitory Fusarium populations in the presence of strong Streptomyces resource competition in more diverse plant communities. Thus, landscape-scale variation in plant species richness may be

  17. Using Remote Sensing Mapping and Growth Response to Environmental Variability to Aide Aquatic Invasive Plant Management

    Science.gov (United States)

    Bubenheim, David L.; Schlick, Greg; Genovese, Vanessa; Wilson, Kenneth D.

    2018-01-01

    Management of aquatic weeds in complex watersheds and river systems present many challenges to assessment, planning and implementation of management practices for floating and submerged aquatic invasive plants. The Delta Region Areawide Aquatic Weed Project (DRAAWP), a USDA sponsored area-wide project, is working to enhance planning, decision-making and operational efficiency in the California Sacramento-San Joaquin Delta. Satellite and airborne remote sensing are used map (area coverage and biomass density), direct operations, and assess management impacts on plant communities. Archived satellite records enable review of results following previous climate and management events and aide in developing long-term strategies. Examples of remote sensing aiding effectiveness of aquatic weed management will be discussed as well as areas for potential technological improvement. Modeling at local and watershed scales using the SWAT modeling tool provides insight into land-use effects on water quality (described by Zhang in same Symposium). Controlled environment growth studies have been conducted to quantify the growth response of invasive aquatic plants to water quality and other environmental factors. Environmental variability occurs across a range of time scales from long-term climate and seasonal trends to short-term water flow mediated variations. Response time for invasive species response are examined at time scales of weeks, day, and hours using a combination of study duration and growth assessment techniques to assess water quality, temperature (air and water), nitrogen, phosphorus, and light effects. These provide response parameters for plant growth models in response to the variation and interact with management and economic models associated with aquatic weed management. Plant growth models are to be informed by remote sensing and applied spatially across the Delta to balance location and type of aquatic plant, growth response to altered environments and

  18. Guidelines for nuclear plant response to an earthquake

    International Nuclear Information System (INIS)

    1989-12-01

    Guidelines have been developed to assist nuclear plant personnel in the preparation of earthquake response procedures for nuclear power plants. The objectives of the earthquake response procedures are to determine (1) the immediate effects of an earthquake on the physical condition of the nuclear power plant, (2) if shutdown of the plant is appropriate based on the observed damage to the plant or because the OBE has been exceeded, and (3) the readiness of the plant to resume operation following shutdown due to an earthquake. Readiness of a nuclear power plant to restart is determined on the basis of visual inspections of nuclear plant equipment and structures, and the successful completion of surveillance tests which demonstrate that the limiting conditions for operation as defined in the plant Technical Specifications are met. The guidelines are based on information obtained from a review of earthquake response procedures from numerous US and foreign nuclear power plants, interviews with nuclear plant operations personnel, and a review of reports of damage to industrial equipment and structures in actual earthquakes. 7 refs., 4 figs., 4 tabs

  19. Effects of Nonnative Ungulate Removal on Plant Communities and Soil Biogeochemistry in Tropical Forests

    Science.gov (United States)

    Cole, R. J.; Litton, C. M.; Giardina, C. P.; Sparks, J. P.

    2014-12-01

    Non-native ungulates have substantial impacts on native ecosystems globally, altering both plant communities and soil biogeochemistry. Across tropical and temperate ecosystems, land managers fence and remove non-native ungulates to conserve native biodiversity, a costly management action, yet long-term outcomes are not well quantified. Specifically, knowledge gaps include: (i) the magnitude and time frame of plant community recovery; (ii) the response of non-native invasive plants; and (iii) changes to soil biogeochemistry. In 2010, we established a series of paired ungulate presence vs. removal plots that span a 20 yr. chronosequence in tropical montane wet forests on the Island of Hawaii to quantify the impacts and temporal legacy of feral pig removal on plant communities and soil biogeochemistry. We also compared soil biogeochemistry in targeted areas of low and high feral pig impact. Our work shows that both native and non-native vegetation respond positively to release from top-down control following removal of feral pigs, but species of high conservation concern recover only if initially present at the time of non-native ungulate removal. Feral pig impacts on soil biogeochemistry appear to last for at least 20 years following ungulate removal. We observed that both soil physical and chemical properties changed with feral pig removal. Soil bulk density and volumetric water content decreased while extractable base cations and inorganic N increased in low vs. high feral pig impact areas. We hypothesize that altered soil biogeochemistry facilitates continued invasions by non-native plants, even decades after non-native ungulate removal. Future work will concentrate on comparisons between wet and dry forest ecosystems and test whether manipulation of soil nutrients can be used to favor native vs. non-native plant establishment.

  20. Community leaders' perspectives on socio-economic impacts of power-plant development

    International Nuclear Information System (INIS)

    Hastings, M.; Cawley, M.E.

    1981-01-01

    The primary focus of this research effort was to identify and measure the socioeconomic impacts of power plant development on non-metropolitan host communities. A mail survey, distributed to community leaders in 100 power plant communities east of the Mississippi River, was utilized to gather information from 713 respondents. Community leaders were questioned as to the plant's impact on (a) community groups, (b) aspects of community life, (c) overall community acceptance and (d) attitudes toward power plant development. Overall, the trends and patterns of plant impact on the host communities were found to be largely positive. Specifically, local employment opportunities were generally enhanced with the advent of the power plant. Directly related to power plant development was the overall improvement of the local economic situation. Off-shoots from such in the economic area included related general improvements in the community quality of life. While the vast majority of community leaders responded with positive comments on power plant presence, adverse impacts were also mentioned. Negative comments focused on environmental problems, deterioration of roads and traffic conditions, and the possibility of nuclear accidents. Despite these negative impacts, almost two-thirds of the community leaders would definitely support the reconstruction of the same energy facility. Power plant development, therefore, is generally perceived as both a positive and beneficial asset for the host area. (author)

  1. On-line acquisition of plant related and environmental parameters (plant monitoring) in gerbera: determining plant responses

    NARCIS (Netherlands)

    Baas, R.; Slootweg, G.

    2004-01-01

    For on-line plant monitoring equipment to be functional in commercial glasshouse horticulture, relations between sensor readings and plant responses on both the short (days) and long term (weeks) are required. For this reason, systems were installed to monitor rockwool grown gerbera plants on a

  2. Response of pest control by generalist predators to local-scale plant diversity: a meta-analysis.

    Science.gov (United States)

    Dassou, Anicet Gbèblonoudo; Tixier, Philippe

    2016-02-01

    Disentangling the effects of plant diversity on the control of herbivores is important for understanding agricultural sustainability. Recent studies have investigated the relationships between plant diversity and arthropod communities at the landscape scale, but few have done so at the local scale. We conducted a meta-analysis of 32 papers containing 175 independent measures of the relationship between plant diversity and arthropod communities. We found that generalist predators had a strong positive response to plant diversity, that is, their abundance increased as plant diversity increased. Herbivores, in contrast, had an overall weak and negative response to plant diversity. However, specialist and generalist herbivores differed in their response to plant diversity, that is, the response was negative for specialists and not significant for generalists. While the effects of scale remain unclear, the response to plant diversity tended to increase for specialist herbivores, but decrease for generalist herbivores as the scale increased. There was no clear effect of scale on the response of generalist predators to plant diversity. Our results suggest that the response of herbivores to plant diversity at the local scale is a balance between habitat and trophic effects that vary according to arthropod specialization and habitat type. Synthesis and applications. Positive effects of plant diversity on generalist predators confirm that, at the local scale, plant diversification of agroecosystems is a credible and promising option for increasing pest regulation. Results from our meta-analysis suggest that natural control in plant-diversified systems is more likely to occur for specialist than for generalist herbivores. In terms of pest management, our results indicate that small-scale plant diversification (via the planting of cover crops or intercrops and reduced weed management) is likely to increase the control of specialist herbivores by generalist predators.

  3. Community response grids: using information technology to help communities respond to bioterror emergencies.

    Science.gov (United States)

    Jaeger, Paul T; Fleischmann, Kenneth R; Preece, Jennifer; Shneiderman, Ben; Wu, Philip Fei; Qu, Yan

    2007-12-01

    Access to accurate and trusted information is vital in preparing for, responding to, and recovering from an emergency. To facilitate response in large-scale emergency situations, Community Response Grids (CRGs) integrate Internet and mobile technologies to enable residents to report information, professional emergency responders to disseminate instructions, and residents to assist one another. CRGs use technology to help residents and professional emergency responders to work together in community response to emergencies, including bioterrorism events. In a time of increased danger from bioterrorist threats, the application of advanced information and communication technologies to community response is vital in confronting such threats. This article describes CRGs, their underlying concepts, development efforts, their relevance to biosecurity and bioterrorism, and future research issues in the use of technology to facilitate community response.

  4. Interspecific nutrient transfer in a tallgrass prairie plant community

    International Nuclear Information System (INIS)

    Walter, L.E.F.; Hartnett, D.C.; Hetrick, B.A.D.; Schwab, A.P.

    1996-01-01

    Interplant nutrient transfer may be an important ecological process in grasslands, and may significantly influence plant neighborhood interactions. We investigated the potential for phosphorus transfer between the dominant grass Andropogon gerardii and several neighboring plant species in tallgrass prairie via a field 32PO4 labelling experiment. The mean amount of 32P received from donor shoots differed significantly among neighboring species and decreased with increasing distance from the donor. In general, forbs and cool-season C3 grasses received more labelled 32P than warm-season C4 grasses. Phosphorus transfer occurred over distances up to 0.5 m. The effects of species and distance on movement of phosphorus changed with increasing time after labelling. The relative mass of receiver and donor shoots did not affect amounts of 32P transfer. A benomyl fungicide treatment, applied to suppress mycorrhizal activity, likely did not affect existing vegetative hyphae and did not affect the amount of 32P transferred. These studies demonstrate that: (1) phosphorus is transferred among neighboring species in tallgrass prairie plant communities, (2) phosphorus may be transferred over significantly greater distances than reported in other grasslands, and (3) there is differential transfer among co-occurring species. Hypothesized mechanisms accounting for these patterns in tallgrass prairie include mycorrhizal hyphal interconnections and/or extensive and differential root and rhizosphere overlap among neighboring species

  5. Regulation of abiotic and biotic stress responses by plant hormones

    DEFF Research Database (Denmark)

    Grosskinsky, Dominik Kilian; van der Graaff, Eric; Roitsch, Thomas Georg

    2016-01-01

    Plant hormones (phytohormones) are signal molecules produced within the plant, and occur in very low concentrations. In the present chapter, the current knowledge on the regulation of biotic and biotic stress responses by plant hormones is summarized with special focus on the novel insights...... into the complex hormonal crosstalk of classical growth stimulating plant hormones within the naturally occurring biotic and abiotic multistress environment of higher plants. The MAPK- and phytohormone-cascades which comprise a multitude of single molecules on different signalling levels, as well as interactions...

  6. Ecology of some mire and bog plant communities in the Western Italian Alps

    Directory of Open Access Journals (Sweden)

    Giorgio BUFFA

    2003-02-01

    Full Text Available During a mire vegetation study, conducted mainly in the subalpine-alpine sector of the Western Italian Alps, the ecology of several plant communities and numerous moss species of this kind of vegetation was evaluated. The study area covered the Piedmontese sector of the Graian Alps, the eastern sector of the Aosta Valley as well as certain localities of the Pennine Alps, the Canavese district and the Maritime Alps. They have a rocky substratum representative of the various regional lithologies and include the main sectors characterised by the highest precipitation. Three hundred and twenty two relevées were made using the phytosociological method and the pH and the conductivity of the water table and its depth were measured directly. Cluster Analysis allowed a classification of the samples and the identification of various groups of plant communities. Ordination performed by DCA and CCA allowed us to identify the ecological features of the various plant communities by using the values of the main environmental parameters, measured directly in the field, and certain climatic parameters (altitude and mean annual precipitation available. The use of climatic parameters is an important result for identifying communities which show greater oceanicity, something that is underlined also by the presence of indicator species such as Sphagnum papillosum and S. subnitens. Furthermore the communities are arranged in a "poor-rich" gradient, and are also profoundly influenced by depth to water table which is inversely correlated to the pH. Therefore we find certain kinds of communities all with a very low water table and which are little affected by its chemistry. Other groups share the fact that the water table is outcropping or near the surface and are distinguishable for their pH values and conductivity. We discuss the different response of the bryophytes and vascular plants of these communities to the environmental parameters considered, in light of their

  7. Higher Plants in Space: Microgravity Perception, Response, and Adaptation

    Science.gov (United States)

    Zheng, Hui Qiong; Han, Fei; Le, Jie

    2015-11-01

    Microgravity is a major abiotic stress in space. Its effects on plants may depend on the duration of exposure. We focused on two different phases of microgravity responses in space. When higher plants are exposed to short-term (seconds to hours) microgravity, such as on board parabolic flights and sounding rockets, their cells usually exhibit abiotic stress responses. For example, Ca 2+-, lipid-, and pH-signaling are rapidly enhanced, then the production of reactive oxygen species and other radicals increase dramatically along with changes in metabolism and auxin signaling. Under long-term (days to months) microgravity exposure, plants acclimatize to the stress by changing their metabolism and oxidative response and by enhancing other tropic responses. We conclude by suggesting that a systematic analysis of regulatory networks at the molecular level of higher plants is needed to understand the molecular signals in the distinct phases of the microgravity response and adaptation.

  8. Divergent composition but similar function of soil food webs of individual plants: plant species and community effects

    NARCIS (Netherlands)

    Bezemer, T.M.; Fountain, T.; Barea, J.M.; Christensen, S.; Dekker, S.C.; Duyts, H.; Hal, van R.; Harvey, J.A.; Hedlund, K.; Maraun, M.; Mikola, J.; Mladenov, A.G.; Robin, C.; Ruiter, de P.C.; Scheu, H.; Setälä, S.; šmilauer, P.; Putten, van der W.H.

    2010-01-01

    Soils are extremely rich in biodiversity, and soil organisms play pivotal roles in supporting terrestrial life, but the role that individual plants and plant communities play in influencing the diversity and functioning of soil food webs remains highly debated. Plants, as primary producers and

  9. Divergent composition but similar function of soil food webs beneath individual plants: plant species and community effects

    NARCIS (Netherlands)

    Bezemer, T.M.; Fountain, M.T.; Barea, J.M.; Christensen, S.; Dekker, S.C.; Duyts, H.; van Hal, R.; Harvey, J.A.; Hedlund, K.; Maraun, M.; Mikola, J.; Mladenov, A.G.; Robin, C.; de Ruiter, P.C.; Scheu, S.; Setälä, H.; Milauer, P.; Van der Putten, W.H.

    2010-01-01

    Soils are extremely rich in biodiversity, and soil organisms play pivotal roles in supporting terrestrial life, but the role that individual plants and plant communities play in influencing the diversity and functioning of soil food webs remains highly debated. Plants, as primary producers and

  10. Defining groundwater-dependent ecosystems and assessing critical water needs for their foundational plant communities

    Science.gov (United States)

    Stella, J. C.

    2017-12-01

    In many water-limited regions, human water use in conjunction with increased climate variability threaten the sustainability of groundwater-dependent plant communities and the ecosystems that depend on them (GDEs). Identifying and delineating vulnerable GDEs and determining critical functional thresholds for their foundational species has proved challenging, but recent research across several disciplines shows great promise for reducing scientific uncertainty and increasing applicability to ecosystem and groundwater management. Combining interdisciplinary approaches provides insights into indicators that may serve as early indicators of ecosystem decline, or alternatively demonstrate lags in responses depending on scale or sensitivity, or that even may decouple over time (Fig. 1). At the plant scale, miniaturization of plant sap flow sensors and tensiometers allow for non-destructive, continual measurements of plant water status in response to environmental stressors. Novel applications of proven tree-ring and stable isotope methods provide multi-decadal chronologies of radial growth, physiological function (using d13C ratios) and source water use (using d18O ratios) in response to annual variation in climate and subsurface water availability to plant roots. At a landscape scale, integration of disparate geospatial data such as hyperspectral imagery and LiDAR, as well as novel spectral mixing analysis promote the development of novel water stress indices such as vegetation greenness and non-photosynthetic (i.e., dead) vegetation (Fig. 2), as well as change detection using time series (Fig. 3). Furthermore, increases in data resolution across numerous data types can increasingly differentiate individual plant species, including sensitive taxa that serve as early warning indicators of ecosystem impairment. Combining and cross-calibrating these approaches provide insight into the full range of GDE response to environmental change, including increased climate drought

  11. A Plant's Response to Gravity as a Wave Guide Phenomenon

    Science.gov (United States)

    Wagner, Orvin

    1997-11-01

    Plant experimental data provides a unifying wave theory (W-wave theory) for the growth and development of plants. A plant's response to gravity is an important aspect of this theory. It appears that a plant part is tuned to the angle with which it initially grew with respect to the gravitational field and changes produce correction responses. This is true because the velocity of W-waves (whose standing waves determine plant structure) within plant tissue is found to be different in different directions (angle a) with respect to the gravitational field. I found that there are preferred values of a, namely integral multiples of near 5 degrees for some plants. Conifers apparently are more sensitive to the gravitational field than deciduous trees, in the cases studied, so their structure is determined in more detail by the gravitational field. A plant's response to gravity appears to be a fundamental phenomenon and may provide a new model for gravity that can be experimentally verified in the laboratory. Along these same lines accelerometers placed in plant tissue indicate that plants produce gravity related forces that facilitate sap flow. See the

  12. Inter-plant communication through mycorrhizal networks mediates complex adaptive behaviour in plant communities.

    Science.gov (United States)

    Gorzelak, Monika A; Asay, Amanda K; Pickles, Brian J; Simard, Suzanne W

    2015-05-15

    Adaptive behaviour of plants, including rapid changes in physiology, gene regulation and defence response, can be altered when linked to neighbouring plants by a mycorrhizal network (MN). Mechanisms underlying the behavioural changes include mycorrhizal fungal colonization by the MN or interplant communication via transfer of nutrients, defence signals or allelochemicals. We focus this review on our new findings in ectomycorrhizal ecosystems, and also review recent advances in arbuscular mycorrhizal systems. We have found that the behavioural changes in ectomycorrhizal plants depend on environmental cues, the identity of the plant neighbour and the characteristics of the MN. The hierarchical integration of this phenomenon with other biological networks at broader scales in forest ecosystems, and the consequences we have observed when it is interrupted, indicate that underground 'tree talk' is a foundational process in the complex adaptive nature of forest ecosystems. Published by Oxford University Press on behalf of the Annals of Botany Company.

  13. Perceptions about Homeless Elders and Community Responsibility

    Science.gov (United States)

    Kane, Michael N.; Green, Diane; Jacobs, Robin

    2013-01-01

    Human service students were surveyed ("N" = 207) to determine their perceptions about homeless elders and communal responsibility for their well-being. Using a backward regression analysis, a final model ("F" = 15.617, "df" = 7, "p" < 0.001) for Perceptions about Homeless Persons and Community…

  14. Penerapan Corporate Social Responsibility dengan Konsep Community Based Tourism

    Directory of Open Access Journals (Sweden)

    Linda Suriany

    2013-12-01

    Full Text Available Abstract: Business is not only economic institution, but social institution too. As social institution, business has responsibility to help society in solving social problem. This responsibility called Corporate Social Responsibility (CSR. CSR pays attention about social problem and environment, so CSR support continuous development to help government role. Nowadays, our government has national development’s agenda. One of them is tourism sector (Visit Indonesia Year 2008 programmed. But tourism sector has challenge in human resources. In this case, business role in practice CSR is needed to help tourism sector. With CSR activities, the quality of local community will increase to participate in tourism activities. CSR activities include training that based on research. When the quality of local community increase, local community can practice the concept of community based tourism (CBT. In the future, Indonesia has a power to compete with other countries.

  15. Soil microbial community structure and nitrogen cycling responses to agroecosystem management and carbon substrate addition

    Science.gov (United States)

    Berthrong, S. T.; Buckley, D. H.; Drinkwater, L. E.

    2011-12-01

    Fertilizer application in conventional agriculture leads to N saturation and decoupled soil C and N cycling, whereas organic practices, e.g. complex rotations and legume incorporation, often results in increased SOM and tightly coupled cycles of C and N. These legacy effects of management on soils likely affect microbial community composition and microbial process rates. This project tested if agricultural management practices led to distinct microbial communities and if those communities differed in ability to utilize labile plant carbon substrates and to produce more plant available N. We addressed several specific questions in this project. 1) Do organic and conventional management legacies on similar soils produce distinct soil bacterial and fungal community structures and abundances? 2) How do these microbial community structures change in response to carbon substrate addition? 3) How do the responses of the microbial communities influence N cycling? To address these questions we conducted a laboratory incubation of organically and conventionally managed soils. We added C-13 labelled glucose either in one large dose or several smaller pulses. We extracted genomic DNA from soils before and after incubation for TRFLP community fingerprinting. We measured C in soil pools and respiration and N in soil extracts and leachates. Management led to different compositions of bacteria and fungi driven by distinct components in organic soils. Biomass did not differ across treatments indicating that differences in cycling were due to composition rather than abundance. C substrate addition led to convergence in bacterial communities; however management still strongly influenced the difference in communities. Fungal communities were very distinct between managements and plots with substrate addition not altering this pattern. Organic soils respired 3 times more of the glucose in the first week than conventional soils (1.1% vs 0.4%). Organic soils produced twice as much

  16. Plants' responses to drought and shade environments

    African Journals Online (AJOL)

    전병기

    Among them, drought is widely known as the main factor that limits plants' growth, productivity and development (Reddy et al., 2004; Shao et al., 2008; Li et al., 2009). Recently, drought occured frequently all over the globe due to climate changes (Khaine and Woo, 2015). Light and shade are very important environements ...

  17. WRKY transcription factors in plant responses to stresses.

    Science.gov (United States)

    Jiang, Jingjing; Ma, Shenghui; Ye, Nenghui; Jiang, Ming; Cao, Jiashu; Zhang, Jianhua

    2017-02-01

    The WRKY gene family is among the largest families of transcription factors (TFs) in higher plants. By regulating the plant hormone signal transduction pathway, these TFs play critical roles in some plant processes in response to biotic and abiotic stress. Various bodies of research have demonstrated the important biological functions of WRKY TFs in plant response to different kinds of biotic and abiotic stresses and working mechanisms. However, very little summarization has been done to review their research progress. Not just important TFs function in plant response to biotic and abiotic stresses, WRKY also participates in carbohydrate synthesis, senescence, development, and secondary metabolites synthesis. WRKY proteins can bind to W-box (TGACC (A/T)) in the promoter of its target genes and activate or repress the expression of downstream genes to regulate their stress response. Moreover, WRKY proteins can interact with other TFs to regulate plant defensive responses. In the present review, we focus on the structural characteristics of WRKY TFs and the research progress on their functions in plant responses to a variety of stresses. © 2016 Institute of Botany, Chinese Academy of Sciences.

  18. Responses of Two Invasive Plants Under Various Microclimate Conditions in the Seoul Metropolitan Region

    Science.gov (United States)

    Song, Uhram; Mun, Saeromi; Ho, Chang-Hoi; Lee, Eun Ju

    2012-06-01

    The possible consequences of global warming on plant communities and ecosystems have wide-ranging ramifications. We examined how environmental change affects plant growth as a function of the variations in the microclimate along an urban-suburban climate gradient for two allergy-inducing, invasive plants, Humulus japonicus and Ambrosia artemisiifolia var. elatior. The environmental factors and plant growth responses were measured at two urban sites (Gangbuk and Seongbuk) and two suburban sites (Goyang and Incheon) around Seoul, South Korea. The mean temperatures and CO2 concentrations differed significantly between the urban (14.8 °C and 439 ppm CO2) and suburban (13.0 °C and 427 ppm CO2) sites. The soil moisture and nitrogen contents of the suburban sites were higher than those at the urban sites, especially for the Goyang site. The two invasive plants showed significantly higher biomasses and nitrogen contents at the two urban sites. We conducted experiments in a greenhouse to confirm the responses of the plants to increased temperatures, and we found consistently higher growth rates under conditions of higher temperatures. Because we controlled the other factors, the better performance of the two invasive plants appears to be primarily attributable to their responses to temperature. Our study demonstrates that even small temperature changes in the environment can confer significant competitive advantages to invasive species. As habitats become urbanized and warmer, these invasive plants should be able to displace native species, which will adversely affect people living in these areas.

  19. Climate impacts on bird and plant communities from altered animal-plant interactions

    Science.gov (United States)

    Martin, Thomas E.; Maron, John L.

    2012-01-01

    The contribution of climate change to declining populations of organisms remains a question of outstanding concern. Much attention to declining populations has focused on how changing climate drives phenological mismatches between animals and their food. Effects of climate on plant communities may provide an alternative, but particularly powerful, influence on animal populations because plants provide their habitats. Here, we show that abundances of deciduous trees and associated songbirds have declined with decreasing snowfall over 22 years of study in montane Arizona, USA. We experimentally tested the hypothesis that declining snowfall indirectly influences plants and associated birds by allowing greater over-winter herbivory by elk (Cervus canadensis). We excluded elk from one of two paired snowmelt drainages (10 ha per drainage), and replicated this paired experiment across three distant canyons. Over six years, we reversed multi-decade declines in plant and bird populations by experimentally inhibiting heavy winter herbivory associated with declining snowfall. Moreover, predation rates on songbird nests decreased in exclosures, despite higher abundances of nest predators, demonstrating the over-riding importance of habitat quality to avian recruitment. Thus, our results suggest that climate impacts on plant–animal interactions can have forceful ramifying effects on plants, birds, and ecological interactions.

  20. Plant Communities Rather than Soil Properties Structure Arbuscular Mycorrhizal Fungal Communities along Primary Succession on a Mine Spoil

    Science.gov (United States)

    Krüger, Claudia; Kohout, Petr; Janoušková, Martina; Püschel, David; Frouz, Jan; Rydlová, Jana

    2017-01-01

    Arbuscular mycorrhizal fungal (AMF) community assembly during primary succession has so far received little attention. It remains therefore unclear, which of the factors, driving AMF community composition, are important during ecosystem development. We addressed this question on a large spoil heap, which provides a mosaic of sites in different successional stages under different managements. We selected 24 sites of c. 12, 20, 30, or 50 years in age, including sites with spontaneously developing vegetation and sites reclaimed by alder plantations. On each site, we sampled twice a year roots of the perennial rhizomatous grass Calamagrostis epigejos (Poaceae) to determine AMF root colonization and diversity (using 454-sequencing), determined the soil chemical properties and composition of plant communities. AMF taxa richness was unaffected by site age, but AMF composition variation increased along the chronosequences. AMF communities were unaffected by soil chemistry, but related to the composition of neighboring plant communities of the sampled C. epigejos plants. In contrast, the plant communities of the sites were more distinctively structured than the AMF communities along the four successional stages. We conclude that AMF and plant community successions respond to different factors. AMF communities seem to be influenced by biotic rather than by abiotic factors and to diverge with successional age. PMID:28473828

  1. Informal Learning in Online Knowledge Communities: Predicting Community Response to Visitor Inquiries

    NARCIS (Netherlands)

    Nistor, Nicolae; Dascalu, Mihai; Stavarache, Lucia Larise; Serafin, Yvonne; Trausan-Matu, Stefan

    2016-01-01

    Nistor, N., Dascalu, M., Stavarache, L.L., Serafin, Y., & Trausan-Matu, S. (2015). Informal Learning in Online Knowledge Communities: Predicting Community Response to Visitor Inquiries. In G. Conole, T. Klobucar, C. Rensing, J. Konert & É. Lavoué (Eds.), 10th European Conf. on Technology Enhanced

  2. The social responsibility commitment to the community and care environment

    Directory of Open Access Journals (Sweden)

    Martha Elena López Regalado

    2015-12-01

    Full Text Available The concept of csr has evolved in recent years, currently the main objective of the Company cannot lie only meet the monetary needs of the shareholders, but to seek the participation of all stakeholders in the company, with the different stakeholders that interact with the environment either customers, suppliers, employees and society at large, impacting the community with socially responsible actions. Because the concept has acquired new shades as social, economic and environmental responsibility among others, being on the great responsibility of the actions of companies to make social or common good acts to achieve their objectives without harming their economies community, the next job is presented focusing especially on two major indicators of social responsibility such as environmental care, and welfare of the community.

  3. Review of Signal Crosstalk in Plant Stress Responses

    Science.gov (United States)

    This book was prepared to summarize the current understanding of the dynamics of plant response to biotic and abiotic stresses. The preface of the book sets the stage for the contents of the different chapters by outlining that plants defend themselves from various environmental stresses through a v...

  4. Plant Responses to Pathogen Attack: Small RNAs in Focus.

    Science.gov (United States)

    Islam, Waqar; Noman, Ali; Qasim, Muhammad; Wang, Liande

    2018-02-08

    Small RNAs (sRNA) are a significant group of gene expression regulators for multiple biological processes in eukaryotes. In plants, many sRNA silencing pathways produce extensive array of sRNAs with specialized roles. The evidence on record advocates for the functions of sRNAs during plant microbe interactions. Host sRNAs are reckoned as mandatory elements of plant defense. sRNAs involved in plant defense processes via different pathways include both short interfering RNA (siRNA) and microRNA (miRNA) that actively regulate immunity in response to pathogenic attack via tackling pathogen-associated molecular patterns (PAMPs) and other effectors. In response to pathogen attack, plants protect themselves with the help of sRNA-dependent immune systems. That sRNA-mediated plant defense responses play a role during infections is an established fact. However, the regulations of several sRNAs still need extensive research. In this review, we discussed the topical advancements and findings relevant to pathogen attack and plant defense mediated by sRNAs. We attempted to point out diverse sRNAs as key defenders in plant systems. It is hoped that sRNAs would be exploited as a mainstream player to achieve food security by tackling different plant diseases.

  5. Plant natriuretic peptides are apoplastic and paracrine stress response molecules

    KAUST Repository

    Wang, Yuhua; Gehring, Christoph A; Irving, Helen R.

    2011-01-01

    plant stress responses and that, much like in animals, peptide signaling molecules can create diverse and modular signals essential for growth, development and defense under rapidly changing environmental conditions. © 2011 The Author.

  6. Photosynthetic responses of pea plants (Pisum sativum L. cv. Little ...

    African Journals Online (AJOL)

    STORAGESEVER

    2008-08-04

    Aug 4, 2008 ... (O3) have fundamental effects on CO2 exchange by plants. ... produce responses such as reduced photosynthetic rates and earlier senescence .... quality localities treatments and two soil regimes in Riyadh city, KSA. Pn rates.

  7. Comparing herbaceous plant communities in active and passive riparian restoration.

    Directory of Open Access Journals (Sweden)

    Elise S Gornish

    Full Text Available Understanding the efficacy of passive (reduction or cessation of environmental stress and active (typically involving planting or seeding restoration strategies is important for the design of successful revegetation of degraded riparian habitat, but studies explicitly comparing restoration outcomes are uncommon. We sampled the understory herbaceous plant community of 103 riparian sites varying in age since restoration (0 to 39 years and revegetation technique (active, passive, or none to compare the utility of different approaches on restoration success across sites. We found that landform type, percent shade, and summer flow helped explain differences in the understory functional community across all sites. In passively restored sites, grass and forb cover and richness were inversely related to site age, but in actively restored sites forb cover and richness were inversely related to site age. Native cover and richness were lower with passive restoration compared to active restoration. Invasive species cover and richness were not significantly different across sites. Although some of our results suggest that active restoration would best enhance native species in degraded riparian areas, this work also highlights some of the context-dependency that has been found to mediate restoration outcomes. For example, since the effects of passive restoration can be quite rapid, this approach might be more useful than active restoration in situations where rapid dominance of pioneer species is required to arrest major soil loss through erosion. As a result, we caution against labeling one restoration technique as better than another. Managers should identify ideal restoration outcomes in the context of historic and current site characteristics (as well as a range of acceptable alternative states and choose restoration approaches that best facilitate the achievement of revegetation goals.

  8. Humans as long-distance dispersers of rural plant communities.

    Directory of Open Access Journals (Sweden)

    Alistair G Auffret

    Full Text Available Humans are known for their capacity to disperse organisms long distances. Long-distance dispersal can be important for species threatened by habitat destruction, but research into human-mediated dispersal is often focused upon few and/or invasive species. Here we use citizen science to identify the capacity for humans to disperse seeds on their clothes and footwear from a known species pool in a valuable habitat, allowing for an assessment of the fraction and types of species dispersed by humans in an alternative context. We collected material from volunteers cutting 48 species-rich meadows throughout Sweden. We counted 24,354 seeds of 197 species, representing 34% of the available species pool, including several rare and protected species. However, 71 species (36% are considered invasive elsewhere in the world. Trait analysis showed that seeds with hooks or other appendages were more likely to be dispersed by humans, as well as those with a persistent seed bank. More activity in a meadow resulted in more dispersal, both in terms of species and representation of the source communities. Average potential dispersal distances were measured at 13 km. We consider humans capable seed dispersers, transporting a significant proportion of the plant communities in which they are active, just like more traditional vectors such as livestock. When rural populations were larger, people might have been regular and effective seed dispersers, and the net rural-urban migration resulting in a reduction in humans in the landscape may have exacerbated the dispersal failure evident in declining plant populations today. With the fragmentation of habitat and changes in land use resulting from agricultural change, and the increased mobility of humans worldwide, the dispersal role of humans may have shifted from providers of regular local and landscape dispersal to providers of much rarer long-distance and regional dispersal, and international invasion.

  9. Genetic and epigenetic control of plant heat responses

    Directory of Open Access Journals (Sweden)

    Junzhong eLiu

    2015-04-01

    Full Text Available Plants have evolved sophisticated genetic and epigenetic regulatory systems to respond quickly to unfavorable environmental conditions such as heat, cold, drought, and pathogen infections. In particular, heat greatly affects plant growth and development, immunity and circadian rhythm, and poses a serious threat to the global food supply. According to temperatures exposing, heat can be usually classified as warm ambient temperature (about 22-27℃, high temperature (27-30℃ and extremely high temperature (37-42℃, also known as heat stress for the model plant Arabidopsis thaliana. The genetic mechanisms of plant responses to heat have been well studied, mainly focusing on elevated ambient temperature-mediated morphological acclimation and acceleration of flowering, modulation of plant immunity and circadian clock by high temperatures, and thermotolerance to heat stress. Recently, great progress has been achieved on epigenetic regulation of heat responses, including DNA methylation, histone modifications, histone variants, ATP-dependent chromatin remodeling, histone chaperones, small RNAs, long non-coding RNAs and other undefined epigenetic mechanisms. These epigenetic modifications regulate the expression of heat-responsive genes and function to prevent heat-related damage. This review focuses on recent progresses regarding the genetic and epigenetic control of heat responses in plants, and pays more attention to the role of the major epigenetic mechanisms in plant heat responses. Further research perspectives are also discussed.

  10. Phylogenetic composition of host plant communities drives plant-herbivore food web structure.

    Science.gov (United States)

    Volf, Martin; Pyszko, Petr; Abe, Tomokazu; Libra, Martin; Kotásková, Nela; Šigut, Martin; Kumar, Rajesh; Kaman, Ondřej; Butterill, Philip T; Šipoš, Jan; Abe, Haruka; Fukushima, Hiroaki; Drozd, Pavel; Kamata, Naoto; Murakami, Masashi; Novotny, Vojtech

    2017-05-01

    Insects tend to feed on related hosts. The phylogenetic composition of host plant communities thus plays a prominent role in determining insect specialization, food web structure, and diversity. Previous studies showed a high preference of insect herbivores for congeneric and confamilial hosts suggesting that some levels of host plant relationships may play more prominent role that others. We aim to quantify the effects of host phylogeny on the structure of quantitative plant-herbivore food webs. Further, we identify specific patterns in three insect guilds with different life histories and discuss the role of host plant phylogeny in maintaining their diversity. We studied herbivore assemblages in three temperate forests in Japan and the Czech Republic. Sampling from a canopy crane, a cherry picker and felled trees allowed a complete census of plant-herbivore interactions within three 0·1 ha plots for leaf chewing larvae, miners, and gallers. We analyzed the effects of host phylogeny by comparing the observed food webs with randomized models of host selection. Larval leaf chewers exhibited high generality at all three sites, whereas gallers and miners were almost exclusively monophagous. Leaf chewer generality dropped rapidly when older host lineages (5-80 myr) were collated into a single lineage but only decreased slightly when the most closely related congeneric hosts were collated. This shows that leaf chewer generality has been maintained by feeding on confamilial hosts while only a few herbivores were shared between more distant plant lineages and, surprisingly, between some congeneric hosts. In contrast, miner and galler generality was maintained mainly by the terminal nodes of the host phylogeny and dropped immediately after collating congeneric hosts into single lineages. We show that not all levels of host plant phylogeny are equal in their effect on structuring plant-herbivore food webs. In the case of generalist guilds, it is the phylogeny of deeper

  11. Plant pathogens structure arthropod communities across multiple spatial and temporal scales

    NARCIS (Netherlands)

    Tack, A.J.M.; Dicke, M.

    2013-01-01

    Plant pathogens and herbivores frequently co-occur on the same host plants. Despite this, little is known about the impact of their interactions on the structure of plant-based ecological communities. Here, we synthesize evidence that indicates that plant pathogens may profoundly impact arthropod

  12. Plant Responses to Abiotic Stress Regulated by Histone Deacetylases

    Directory of Open Access Journals (Sweden)

    Ming Luo

    2017-12-01

    Full Text Available In eukaryotic cells, histone acetylation and deacetylation play an important role in the regulation of gene expression. Histone acetylation levels are modulated by histone acetyltransferases and histone deacetylases (HDACs. Recent studies indicate that HDACs play essential roles in the regulation of gene expression in plant response to environmental stress. In this review, we discussed the recent advance regarding the plant HDACs and their functions in the regulation of abiotic stress responses. The role of HDACs in autophagy was also discussed.

  13. Herbivory of an invasive slug is affected by earthworms and the composition of plant communities.

    Science.gov (United States)

    Zaller, Johann G; Parth, Myriam; Szunyogh, Ilona; Semmelrock, Ines; Sochurek, Susanne; Pinheiro, Marcia; Frank, Thomas; Drapela, Thomas

    2013-05-13

    Biodiversity loss and species invasions are among the most important human-induced global changes. Moreover, these two processes are interlinked as ecosystem invasibility is considered to increase with decreasing biodiversity. In temperate grasslands, earthworms serve as important ecosystem engineers making up the majority of soil faunal biomass. Herbivore behaviour has been shown to be affected by earthworms, however it is unclear whether these effects differ with the composition of plant communities. To test this we conducted a mesocosm experiment where we added earthworms (Annelida: Lumbricidae) to planted grassland communities with different plant species composition (3 vs. 12 plant spp.). Plant communities had equal plant densities and ratios of the functional groups grasses, non-leguminous forbs and legumes. Later, Arion vulgaris slugs (formerly known as A. lusitanicus; Gastropoda: Arionidae) were added and allowed to freely choose among the available plant species. This slug species is listed among the 100 worst alien species in Europe. We hypothesized that (i) the food choice of slugs would be altered by earthworms' specific effects on the growth and nutrient content of plant species, (ii) slug herbivory will be less affected by earthworms in plant communities containing more plant species than in those with fewer plant species because of a more readily utilization of plant resources making the impacts of earthworms less pronounced. Slug herbivory was significantly affected by both earthworms and plant species composition. Slugs damaged 60% less leaves when earthworms were present, regardless of the species composition of the plant communities. Percent leaf area consumed by slugs was 40% lower in communities containing 12 plant species; in communities containing only three species earthworms increased slug leaf area consumption. Grasses were generally avoided by slugs. Leaf length and number of tillers was increased in mesocosms containing more plant

  14. Responsiveness of performance and morphological traits to experimental submergence predicts field distribution pattern of wetland plants

    NARCIS (Netherlands)

    Luo, Fang-Li; Huang, Lin; Lei, Ting; Xue, Wei; Li, Hong-Li; Yu, Fei-Hai; Cornelissen, J.H.C.

    2016-01-01

    Question: Plant trait mean values and trait responsiveness to different environmental regimes are both important determinants of plant field distribution, but the degree to which plant trait means vs trait responsiveness predict plant distribution has rarely been compared quantitatively. Because

  15. Pesticides from wastewater treatment plant effluents affect invertebrate communities.

    Science.gov (United States)

    Münze, Ronald; Hannemann, Christin; Orlinskiy, Polina; Gunold, Roman; Paschke, Albrecht; Foit, Kaarina; Becker, Jeremias; Kaske, Oliver; Paulsson, Elin; Peterson, Märit; Jernstedt, Henrik; Kreuger, Jenny; Schüürmann, Gerrit; Liess, Matthias

    2017-12-01

    We quantified pesticide contamination and its ecological impact up- and downstream of seven wastewater treatment plants (WWTPs) in rural and suburban areas of central Germany. During two sampling campaigns, time-weighted average pesticide concentrations (c TWA ) were obtained using Chemcatcher® passive samplers; pesticide peak concentrations were quantified with event-driven samplers. At downstream sites, receiving waters were additionally grab sampled for five selected pharmaceuticals. Ecological effects on macroinvertebrate structure and ecosystem function were assessed using the biological indicator system SPEAR pesticides (SPEcies At Risk) and leaf litter breakdown rates, respectively. WWTP effluents substantially increased insecticide and fungicide concentrations in receiving waters; in many cases, treated wastewater was the exclusive source for the neonicotinoid insecticides acetamiprid and imidacloprid in the investigated streams. During the ten weeks of the investigation, five out of the seven WWTPs increased in-stream pesticide toxicity by a factor of three. As a consequence, at downstream sites, SPEAR values and leaf litter degradation rates were reduced by 40% and 53%, respectively. The reduced leaf litter breakdown was related to changes in the macroinvertebrate communities described by SPEAR pesticides and not to altered microbial activity. Neonicotinoids showed the highest ecological relevance for the composition of invertebrate communities, occasionally exceeding the Regulatory Acceptable Concentrations (RACs). In general, considerable ecological effects of insecticides were observed above and below regulatory thresholds. Fungicides, herbicides and pharmaceuticals contributed only marginally to acute toxicity. We conclude that pesticide retention of WWTPs needs to be improved. Copyright © 2017 Elsevier B.V. All rights reserved.

  16. Site response calculations for nuclear power plants

    International Nuclear Information System (INIS)

    Wight, L.H.

    1975-01-01

    Six typical sites consisting of three soil profiles with average shear wave velocities of 800, 1800, and 5000 ft/sec as well as two soil depths of 200 and 400 ft were considered. Seismic input to these sites was a synthetic accelerogram applied at the surface and corresponding to a statistically representative response spectrum. The response of each of these six sites to this input was calculated with the SHAKE program. The results of these calculations are presented

  17. Plant community structure in an oligohaline tidal marsh

    Science.gov (United States)

    Brewer, J.S.; Grace, J.B.

    1990-01-01

    An oligohaline tidal marsh on the northern shore of Lake Pontchartrain, LA was characterized with respect to the distributions and abundances of plant species over spatial and temporal gradients using Detrended Correspondence Analysis (DCA). In addition, the species distributions were correlated to several physical environmental factors using Detrended Canonical Correspondence Analysis (DCCA). The distributions of species were best correlated with distance from Lake Pontchartrain, and to a lesser extent with elevation and substrate organic matter. They were least correlated with mean soil salinity (referred to here as background salinity). Of the three mid-seasonal dominant species, the perennial grass, Spartina patens, is the most salt tolerant and was found closest to the lake. Further inland the dominant perennial was Sagittaria lancifolia, which has a salt tolerance less than that of Spartina patens. The perennial sedge, Cladium jamaicense, which is the least salt tolerant of the three, was dominant furthest inland. Background salinity levels were generally low (interactions likely also play a role in structuring the plant community. The distributions of several annuals depended on the size and life history of the mid-seasonal dominant perennials. Most of the annuals frequently co-occurred with Sagittaria lancifolia, which was the shortest in stature and had the least persistent canopy of the three mid-seasonal dominant perennials.

  18. Plant response to heavy metals and organic pollutants in cell culture and at whole plant level

    Energy Technology Data Exchange (ETDEWEB)

    Golan-Goldhirsh, A.; Barazani, O. [Ben-Gurion Univ. of The Negev, The Jacob Blaustein Inst. for Desert Research, Albert Katz Dept. of Dryland Biotechnologies, Desert Plant Biotechnology Lab., Sede Boqer Campus (Israel); Nepovim, A.; Soudek, P.; Vanek, T. [Inst. of Organic Chemistry and Biochemistry (Czech Republic); Smrcek, S.; Dufkova, L.; Krenkova, S. [Faculty of Natural Sciences, Charles Univ. (Czech Republic); Yrjala, K. [Univ. of Helsinki, Dept. of Biosciences, Div. of General Microbiology, Helsinki (Finland); Schroeder, P. [Inst. for Soil Ecology, GSF National Research Center for Environment and Health, Neuherberg, Oberschleissheim (Germany)

    2004-07-01

    Background. Increasing awareness in the last decade concerning environmental quality had prompted research into 'green solutions' for soil and water remediation, progressing from laboratory in vitro experiments to pot and field trials. In vitro cell culture experiments provide a convenient system to study basic biological processes, by which biochemical pathways, enzymatic activity and metabolites can be specifically studied. However, it is difficult to relate cell cultures, calli or even hydroponic experiments to the whole plant response to pollutant stress. In the field, plants are exposed to additional a-biotic and biotic factors, which complicate further plant response. Hence, we often see that in vitro selected species perform poorly under soil and field conditions. Soil physical and chemical properties, plant-mycorrhizal association and soil-microbial activity affect the process of contaminant degradation by plants and/or microorganisms, pointing to the importance of pot and field experiments. Objective. This paper is a joint effort of a group of scientists in COST action 837. It represents experimental work and an overview on plant response to environmental stress from in vitro tissue culture to whole plant experiments in soil. Results. Results obtained from in vitro plant tissue cultures and whole plant hydroponic experiments indicate the phytoremediation potential of different plant species and the biochemical mechanisms involved in plant tolerance. In pot experiments, several selected desert plant species, which accumulated heavy metal in hydroponic systems, succeeded in accumulating the heavy metal in soil conditions as well. Conclusions and recommendations. In vitro plant tissue cultures provide a useful experimental system for the study of the mechanisms involved in the detoxification of organic and heavy metal pollutants. However, whole plant experimental systems, as well as hydroponics followed by pot and field trials, are essential when

  19. Differential responses of soil bacteria, fungi, archaea and protists to plant species richness and plant functional group identity

    NARCIS (Netherlands)

    Dassen, S.; Cortois, R.; Martens, Henk; De Hollander, M.; Kowalchuk, G.A.; van der Putten, W.H.; De Deyn, G.B.

    2017-01-01

    Plants are known to influence belowground microbial community structure along their roots, but the impacts of plant species richness and plant functional group (FG) identity on microbial communities in the bulk soil are still not well understood. Here, we used 454-pyrosequencing to analyse the soil

  20. The acceptability of community leaders in establishing a nuclear power plant in Thailand: a case study of Chumphon province

    International Nuclear Information System (INIS)

    Aukaravarothai, A.

    1998-01-01

    Acceptability of community leaders regarding the establishment of a nuclear power plant in Amphoe Pathiu of Chumphon Province in studied. The objectives are to investigate the level of understanding, the attitudes of acceptance and the possible benefits the community expects from the establishment of a nuclear power plant in the province. The study method involved interviewing the selected 118 community leaders and then applying the statistical method to analysis their responses and obtain a general description of the acceptability. The Chi-quire method was used to test the hypothesis at the confidence levels of 95% and 99%. The results revealed that 88.1% of the respondents were male and 11.9% were female, 88.2% have lived there permanently, 39.8% were university graduates and 48.3% are government officials, 48.3% were acceptable about the establishment of the nuclear power plant, 54.2% were not acceptable and 29.7% were ambiguous because they were afraid and uncertain about the safety of the power plant. In the acceptable group there was no correlation between the responses and the general Background of the respondents, i.e. age, occupation, education and field of study. However, in the unacceptable and ambiguous groups, a correlation was found between their responses and general background. This could be due to an information drive in the community prior to this study

  1. Mineralogical composition changes of postagrogenic soils under different plant communities.

    Science.gov (United States)

    Churilin, Nikita; Chizhikova, Natalia; Varlamov, Evgheni; Churilina, Alexandra

    2017-04-01

    Plant communities play the leading role in transformation of soil. The need of studying former arable lands increases due to large number of abandoned lands in Russia. It is necessary to study mineralogical composition of soils involved into natural processes to understand the trends of their development after agricultural activities in the past. The aim of the study is to identify changes in mineralogical composition of soils under the influence of different plant communities. Soils were sampled in the south of Arkhangelsk region, Ustyansky district, near Akichkin Pochinok village. Soils are formed on clay moraine of Moscow glaciation. Soil profiles were dug on interfluve. We selected 4 plant communities on different stages of succession: upland meadow with domination of sod grasses (Phleum pratense, Agrostis tenuis), 16-year-old birch forest where dominants are herbaceous plants such as Poa sp., Chamerion angustiflium, Agrostis tenuis, 16-year-old spruce forest with no herbaceous vegetation and 70-year-old bilberry spruce forest with domination of Vaccinium myrtillus and Vaccinium vitis-idaea. To separate soil fractions mineral content. We noticed a clear differentiation of studied soils both in the content of fraction and composition of minerals. Mineralogical composition and major mineral phases correlation of profiles under 70 years and 16 years of spruce forests are different. Mineralogical content in upper part of profile under the young spruce is more differentiated than in old spruce forest: the amount of quartz and kaolinite increases in upper horizon, although in this case the overall pattern of profile formation of clay material during podzolization remains unchanged. There is more substantial desilting under the birch forest, compared with profile under the spruce of same age within top 50 cm. Under the meadow vegetation we've discovered differentiation in mineral composition. Upper horizons contain smectite phase and differ from the underlying

  2. Plant hydraulic diversity buffers forest ecosystem responses to drought

    Science.gov (United States)

    Anderegg, W.; Konings, A. G.; Trugman, A. T.; Pacala, S. W.; Yu, K.; Sulman, B. N.; Sperry, J.; Bowling, D. R.

    2017-12-01

    Drought impacts carbon, water, and energy cycles in forests and may pose a fundamental threat to forests in future climates. Plant hydraulic transport of water is central to tree drought responses, including curtailing of water loss and the risk of mortality during drought. The effect of biodiversity on ecosystem function has typically been examined in grasslands, yet the diversity of plant hydraulic strategies may influence forests' response to drought. In a combined analysis of eddy covariance measurements, remote-sensing data of plant water content variation, model simulations, and plant hydraulic trait data, we test the degree to which plant water stress schemes influence the carbon cycle and how hydraulic diversity within and across ecosystems affects large-scale drought responses. We find that current plant functional types are not well-suited to capture hydraulic variation and that higher hydraulic diversity buffers ecosystem variation during drought. Our results demonstrate that tree functional diversity, particularly hydraulic diversity, may be critical to simulate in plant functional types in current land surface model projections of future vegetation's response to climate extremes.

  3. Do plants modulate biomass allocation in response to petroleum pollution?

    Science.gov (United States)

    Nie, Ming; Yang, Qiang; Jiang, Li-Fen; Fang, Chang-Ming; Chen, Jia-Kuan; Li, Bo

    2010-01-01

    Biomass allocation is an important plant trait that responds plastically to environmental heterogeneities. However, the effects on this trait of pollutants owing to human activities remain largely unknown. In this study, we investigated the response of biomass allocation of Phragmites australis to petroleum pollution by a 13CO2 pulse-labelling technique. Our data show that plant biomass significantly decreased under petroleum pollution, but the root–shoot ratio for both plant biomass and 13C increased with increasing petroleum concentration, suggesting that plants could increase biomass allocation to roots in petroleum-polluted soil. Furthermore, assimilated 13C was found to be significantly higher in soil, microbial biomass and soil respiration after soils were polluted by petroleum. These results suggested that the carbon released from roots is rapidly turned over by soil microbes under petroleum pollution. This study found that plants can modulate biomass allocation in response to petroleum pollution. PMID:20484231

  4. Temperature sensitivity of soil respiration rates enhanced by microbial community response.

    Science.gov (United States)

    Karhu, Kristiina; Auffret, Marc D; Dungait, Jennifer A J; Hopkins, David W; Prosser, James I; Singh, Brajesh K; Subke, Jens-Arne; Wookey, Philip A; Agren, Göran I; Sebastià, Maria-Teresa; Gouriveau, Fabrice; Bergkvist, Göran; Meir, Patrick; Nottingham, Andrew T; Salinas, Norma; Hartley, Iain P

    2014-09-04

    Soils store about four times as much carbon as plant biomass, and soil microbial respiration releases about 60 petagrams of carbon per year to the atmosphere as carbon dioxide. Short-term experiments have shown that soil microbial respiration increases exponentially with temperature. This information has been incorporated into soil carbon and Earth-system models, which suggest that warming-induced increases in carbon dioxide release from soils represent an important positive feedback loop that could influence twenty-first-century climate change. The magnitude of this feedback remains uncertain, however, not least because the response of soil microbial communities to changing temperatures has the potential to either decrease or increase warming-induced carbon losses substantially. Here we collect soils from different ecosystems along a climate gradient from the Arctic to the Amazon and investigate how microbial community-level responses control the temperature sensitivity of soil respiration. We find that the microbial community-level response more often enhances than reduces the mid- to long-term (90 days) temperature sensitivity of respiration. Furthermore, the strongest enhancing responses were observed in soils with high carbon-to-nitrogen ratios and in soils from cold climatic regions. After 90 days, microbial community responses increased the temperature sensitivity of respiration in high-latitude soils by a factor of 1.4 compared to the instantaneous temperature response. This suggests that the substantial carbon stores in Arctic and boreal soils could be more vulnerable to climate warming than currently predicted.

  5. Investigating the Effect of Livestock Grazing and Associated Plant Community Shifts on Carbon and Nutrient Cycling in Alberta, Canada

    Science.gov (United States)

    Hewins, D. B.; Chuan, S.; Stolnikova, E.; Bork, E. W.; Carlyle, C. N.; Chang, S. X.

    2015-12-01

    Grassland ecosystems are ubiquitous across the globe covering an estimated 40 % of Earth's terrestrial landmass. These ecosystems are widely valued for providing forage for domestic livestock and a suite of important ecosystem goods and services including carbon (C) storage. Despite storing more than 30 % of soil C globally, the effect of both livestock grazing and the associated change in plant community structure in response to grazing on C and nutrient cycling remains uncertain. To gain a quantitative understanding of the direct and indirect effects of livestock grazing on C and nutrient cycling, we established study sites at 15 existing site localities with paired long-term grazing (ca. 30 y) and non-grazed treatments (totaling 30 unique plant communities). Our sites were distributed widely across Alberta in three distinct grassland bioclimatic zones allowing us to make comparisons across the broad range of climate variability typical of western Canadian grasslands. In each plant community we decomposed 5 common plant species that are known to increase or decrease in response to grazing pressure, a unique plant community sample, and a cellulose paper control. We measured mass loss, initial lignin, C and N concentrations at 0, 1, 3, 6 and 12 months of field incubation. In addition we assayed hydrolytic and oxidative extracellular enzymes associated with for C (n= 5 hydrolytic; phenoloxidase and peroxidase) and nutrients (i.e. N and P; n=1 ea.) cycling from each litter sample at each collection. Our results suggest that by changing the plant community structure, grazing can affect rates of decomposition and associated biogeochemical cycling by changing plant species and associated litter inputs. Moreover, measures of microbial function are controlled by site-specific conditions (e.g. temperature and precipitation), litter chemistry over the course of our incubation.

  6. Mitigating community impacts of energy development: some examples for coal and nuclear generating plants in the U.S

    International Nuclear Information System (INIS)

    Peelle, E.

    1979-01-01

    Three mitigation plans aimed at internalizing community-level social costs are examined at the Tennessee Valley Authority four-unit nuclear plant in Hartsville, Tennessee; the Puget Sound Power and Light two-unit nuclear plant in Skagit, Washington; and the Missouri Basin Power Project three-unit coal plant in Wheatland, Wyoming. Viewed as new institutional responses to social impact mitigation planning, these plans are analyzed in terms of their origins, scope, goals, local participation, financing, and costs. The significance of the plans derives from: (1) their pioneer status; (2) their similarity of scope despite highly diverse regulatory environments; and (3) their custom tailoring to local circumstances

  7. Plant traits determine the phylogenetic structure of arbuscular mycorrhizal fungal communities.

    Science.gov (United States)

    López-García, Álvaro; Varela-Cervero, Sara; Vasar, Martti; Öpik, Maarja; Barea, José M; Azcón-Aguilar, Concepción

    2017-12-01

    Functional diversity in ecosystems has traditionally been studied using aboveground plant traits. Despite the known effect of plant traits on the microbial community composition, their effects on the microbial functional diversity are only starting to be assessed. In this study, the phylogenetic structure of arbuscular mycorrhizal (AM) fungal communities associated with plant species differing in life cycle and growth form, that is, plant life forms, was determined to unravel the effect of plant traits on the functional diversity of this fungal group. The results of the 454 pyrosequencing showed that the AM fungal community composition differed across plant life forms and this effect was dependent on the soil collection date. Plants with ruderal characteristics tended to associate with phylogenetically clustered AM fungal communities. By contrast, plants with resource-conservative traits associated with phylogenetically overdispersed AM fungal communities. Additionally, the soil collected in different seasons yielded AM fungal communities with different phylogenetic dispersion. In summary, we found that the phylogenetic structure, and hence the functional diversity, of AM fungal communities is dependent on plant traits. This finding adds value to the use of plant traits for the evaluation of belowground ecosystem diversity, functions and processes. © 2017 John Wiley & Sons Ltd.

  8. A plant’s perspective of extremes: Terrestrial plant responses to changing climatic variability

    Science.gov (United States)

    Reyer, C.; Leuzinger, S.; Rammig, A.; Wolf, A.; Bartholomeus, R. P.; Bonfante, A.; de Lorenzi, F.; Dury, M.; Gloning, P.; Abou Jaoudé, R.; Klein, T.; Kuster, T. M.; Martins, M.; Niedrist, G.; Riccardi, M.; Wohlfahrt, G.; de Angelis, P.; de Dato, G.; François, L.; Menzel, A.; Pereira, M.

    2013-01-01

    We review observational, experimental and model results on how plants respond to extreme climatic conditions induced by changing climatic variability. Distinguishing between impacts of changing mean climatic conditions and changing climatic variability on terrestrial ecosystems is generally underrated in current studies. The goals of our review are thus (1) to identify plant processes that are vulnerable to changes in the variability of climatic variables rather than to changes in their mean, and (2) to depict/evaluate available study designs to quantify responses of plants to changing climatic variability. We find that phenology is largely affected by changing mean climate but also that impacts of climatic variability are much less studied but potentially damaging. We note that plant water relations seem to be very vulnerable to extremes driven by changes in temperature and precipitation and that heatwaves and flooding have stronger impacts on physiological processes than changing mean climate. Moreover, interacting phenological and physiological processes are likely to further complicate plant responses to changing climatic variability. Phenological and physiological processes and their interactions culminate in even more sophisticated responses to changing mean climate and climatic variability at the species and community level. Generally, observational studies are well suited to study plant responses to changing mean climate, but less suitable to gain a mechanistic understanding of plant responses to climatic variability. Experiments seem best suited to simulate extreme events. In models, temporal resolution and model structure are crucial to capture plant responses to changing climatic variability. We highlight that a combination of experimental, observational and /or modeling studies have the potential to overcome important caveats of the respective individual approaches. PMID:23504722

  9. Water and Nitrogen Limitations of Ecosystem Processes Across Three Dryland Plant Communities

    Science.gov (United States)

    Beltz, C.; Lauenroth, W. K.; Burke, I. C.

    2017-12-01

    The availability of water and nitrogen (N) play a major role in controlling the distribution of ecosystem types and the rates of ecosystem processes across the globe. Both these resources are being altered by human activity. Anthropogenic fixation of N has increased inputs into the biosphere from 0.5 kg N ha-1 yr-1 to upwards of 10 kg N ha-1 yr-1, while the amount and seasonality of precipitation are expected to continue to change. Within dryland environments, the relationships between increasingly available N and ecosystem processes are especially complex due to dryland's characteristic strong limitation by low and highly variable precipitation. Other experiments have shown that this interplay between N and water can cause temporally complex co-limitation and spatially complex responses with variable effects on ecosystems, such as those to net primary productivity, soil respiration, and plant community composition. Research spanning multiple dryland plant communities is critical for generalizing findings to the 40% of the Earth's terrestrial surface covered in dryland ecosystems. Given IPCC projections in which both N availability and precipitation are altered, examining their interactive effect across multiple plant communities is critical to increasing our understanding of the limitations to ecosystem process in drylands. We are studying a gradient of three plant communities representing a C4 grassland (shortgrass steppe), a C3/C4 grassland (mixed grass prairie), and a shrub-dominated ecosystem with C3 and C4 grasses (sagebrush steppe). We added two levels of N (10 kg N ha-1 and 100 kg N ha-1) and increased summer monthly precipitation by 20%. Sites responded differently to treatments, with the scale of effect varying by treatment. The high-level nitrogen increased soil N availability and soil respiration, while decreasing soil carbon in the labile pool in the upper soil layers. These results will allow for better understanding of increased N in combination with

  10. Using Plant Functional Traits and Phylogenies to Understand Patterns of Plant Community Assembly in a Seasonal Tropical Forest in Lao PDR.

    Directory of Open Access Journals (Sweden)

    Manichanh Satdichanh

    Full Text Available Plant functional traits reflect different evolutionary responses to environmental variation, and among extant species determine the outcomes of interactions between plants and their environment, including other plant species. Thus, combining phylogenetic and trait-based information can be a powerful approach for understanding community assembly processes across a range of spatial scales. We used this approach to investigate tree community composition at Phou Khao Khouay National Park (18°14'-18°32'N; 102°38'- 102°59'E, Laos, where several distinct forest types occur in close proximity. The aim of our study was to examine patterns of plant community assembly across the strong environmental gradients evident at our site. We hypothesized that differences in tree community composition were being driven by an underlying gradient in soil conditions. Thus, we predicted that environmental filtering would predominate at the site and that the filtering would be strongest on sandier soil with low pH, as these are the conditions least favorable to plant growth. We surveyed eleven 0.25 ha (50x50 m plots for all trees above 10 cm dbh (1221 individual trees, including 47 families, 70 genera and 123 species and sampled soils in each plot. For each species in the community, we measured 11 commonly studied plant functional traits covering both the leaf and wood economic spectrum traits and we reconstructed a phylogenetic tree for 115 of the species in the community using rbcL and matK sequences downloaded from Genebank (other species were not available. Finally we compared the distribution of trait values and species at two scales (among plots and 10x10m subplots to examine trait and phylogenetic community structures. Although there was strong evidence that an underlying soil gradient was determining patterns of species composition at the site, our results did not support the hypothesis that the environmental filtering dominated community assembly processes

  11. On-line acquisition of plant related and environmental parameters (plant monitoring) in gerbera: determining plant responses

    OpenAIRE

    Baas, R.; Slootweg, G.

    2004-01-01

    For on-line plant monitoring equipment to be functional in commercial glasshouse horticulture, relations between sensor readings and plant responses on both the short (days) and long term (weeks) are required. For this reason, systems were installed to monitor rockwool grown gerbera plants on a minute-to-minute basis from July 2002 until April 2003. Data collected included, amongst others, crop transpiration from lysimeter data (2 m2), canopy temperature using infrared sensors, rockwool water...

  12. On the brink of change: plant responses to climate on the Colorado Plateau

    Science.gov (United States)

    Munson, Seth M.; Belnap, Jayne; Schelz, Charles D.; Moran, Mary; Carolin, Tara W.

    2011-01-01

    The intensification of aridity due to anthropogenic climate change in the southwestern U.S. is likely to have a large impact on the growth and survival of plant species that may already be vulnerable to water stress. To make accurate predictions of plant responses to climate change, it is essential to determine the long-term dynamics of plant species associated with past climate conditions. Here we show how the plant species and functional types across a wide range of environmental conditions in Colorado Plateau national parks have changed with climate variability over the last twenty years. During this time, regional mean annual temperature increased by 0.18°C per year from 1989–1995, 0.06°C per year from 1995–2003, declined by 0.14°C from 2003–2008, and there was high interannual variability in precipitation. Non-metric multidimensional scaling of plant species at long-term monitoring sites indicated five distinct plant communities. In many of the communities, canopy cover of perennial plants was sensitive to mean annual temperature occurring in the previous year, whereas canopy cover of annual plants responded to cool season precipitation. In the perennial grasslands, there was an overall decline of C3 perennial grasses, no change of C4 perennial grasses, and an increase of shrubs with increasing temperature. In the shrublands, shrubs generally showed no change or slightly increased with increasing temperature. However, certain shrub species declined where soil and physical characteristics of a site limited water availability. In the higher elevation woodlands, Juniperus osteosperma and shrub canopy cover increased with increasing temperature, while Pinus edulis at the highest elevation sites was unresponsive to interannual temperature variability. These results from well-protected national parks highlight the importance of temperature to plant responses in a water-limited region and suggest that projected increases in aridity are likely to promote

  13. Plant-plant interactions mediate the plastic and genotypic response of Plantago asiatica to CO

    NARCIS (Netherlands)

    Loon, Van Marloes P.; Rietkerk, Max; Dekker, Stefan C.; Hikosaka, Kouki; Ueda, Miki U.; Anten, Niels P.R.

    2016-01-01

    Background and Aims The rising atmospheric CO2 concentration ([CO2]) is a ubiquitous selective force that may strongly impact species distribution and vegetation functioning. Plant-plant interactions could mediate the trajectory of vegetation responses to elevated

  14. Interactions between plant and rhizosphere microbial communities in a metalliferous soil

    International Nuclear Information System (INIS)

    Epelde, Lur; Becerril, Jose M.; Barrutia, Oihana; Gonzalez-Oreja, Jose A.; Garbisu, Carlos

    2010-01-01

    In the present work, the relationships between plant consortia, consisting of 1-4 metallicolous pseudometallophytes with different metal-tolerance strategies (Thlaspi caerulescens: hyperaccumulator; Jasione montana: accumulator; Rumex acetosa: indicator; Festuca rubra: excluder), and their rhizosphere microbial communities were studied in a mine soil polluted with high levels of Cd, Pb and Zn. Physiological response and phytoremediation potential of the studied pseudometallophytes were also investigated. The studied metallicolous populations are tolerant to metal pollution and offer potential for the development of phytoextraction and phytostabilization technologies. T. caerulescens appears very tolerant to metal stress and most suitable for metal phytoextraction; the other three species enhance soil functionality. Soil microbial properties had a stronger effect on plant biomass rather than the other way around (35.2% versus 14.9%). An ecological understanding of how contaminants, ecosystem functions and biological communities interact in the long-term is needed for proper management of these fragile metalliferous ecosystems. - Rhizosphere microbial communities in highly polluted mine soils are determinant for the growth of pseudometallophytes.

  15. Interactions between plant and rhizosphere microbial communities in a metalliferous soil

    Energy Technology Data Exchange (ETDEWEB)

    Epelde, Lur [NEIKER-Tecnalia, Department of Ecosystems, c/Berreaga 1, E-48160 Derio (Spain); Becerril, Jose M.; Barrutia, Oihana [Department of Plant Biology and Ecology, University of the Basque Country, UPV/EHU, P.O. Box 644, E-48080 Bilbao (Spain); Gonzalez-Oreja, Jose A. [NEIKER-Tecnalia, Department of Ecosystems, c/Berreaga 1, E-48160 Derio (Spain); Garbisu, Carlos, E-mail: cgarbisu@neiker.ne [NEIKER-Tecnalia, Department of Ecosystems, c/Berreaga 1, E-48160 Derio (Spain)

    2010-05-15

    In the present work, the relationships between plant consortia, consisting of 1-4 metallicolous pseudometallophytes with different metal-tolerance strategies (Thlaspi caerulescens: hyperaccumulator; Jasione montana: accumulator; Rumex acetosa: indicator; Festuca rubra: excluder), and their rhizosphere microbial communities were studied in a mine soil polluted with high levels of Cd, Pb and Zn. Physiological response and phytoremediation potential of the studied pseudometallophytes were also investigated. The studied metallicolous populations are tolerant to metal pollution and offer potential for the development of phytoextraction and phytostabilization technologies. T. caerulescens appears very tolerant to metal stress and most suitable for metal phytoextraction; the other three species enhance soil functionality. Soil microbial properties had a stronger effect on plant biomass rather than the other way around (35.2% versus 14.9%). An ecological understanding of how contaminants, ecosystem functions and biological communities interact in the long-term is needed for proper management of these fragile metalliferous ecosystems. - Rhizosphere microbial communities in highly polluted mine soils are determinant for the growth of pseudometallophytes.

  16. Long-term hydrologic effects on marsh plant community structure in the southern Everglades

    Science.gov (United States)

    Busch, David E.; Loftus, W.F.; Bass, O.L.

    1998-01-01

    Although large-scale transformation of Everglades landscapes has occurred during the past century, the patterns of association among hydrologic factors and southern Everglades freshwater marsh vegetation have not been well-defined. We used a 10-year data base on the aquatic biota of Shark Slough to classify vegetation and describe plant community change in intermediate- to long-hydroperiod Everglades marshes. Study area marsh vegetation was quantitatively grouped into associations dominated by 1) Cladium jamaicense, 2) a group of emergents including Eleocharis cellulosa, Sagittaria lancifolia, and Rhyncospora tracyi, 3) taxa associated with algal mats (Utricularia spp. and Bacopa caroliniana), and 4) the grasses Panicum hemitomon and Paspalidium geminatum. During the decade evaluated, the range of water depths that characterized our study sites approached both extremes depicted in the 40-year hydrologic record for the region. Water depths were near the long-term average during the mid-1980s, declined sharply during a late 1980s drought, and underwent a prolonged increase from 1991 through 1995. Overall macrophyte cover varied inversely with water depth, while the response of periphyton was more complex. An ordination analysis, based on plant species abundance, revealed that study area vegetation structure was associated with hydrologic patterns. Marsh plant community structure showed evidence of cyclic interannual variation corresponding to hydrologic change over the decade evaluated. Lower water depths, the occurrence of marl substrates, and high periphyton cover were correlated. These factors contributed to reduced macrophyte cover in portions of the study area from which water had been diverted.

  17. Alien roadside species more easily invade alpine than lowland plant communities in a subarctic mountain ecosystem.

    Directory of Open Access Journals (Sweden)

    Jonas J Lembrechts

    Full Text Available 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.

  18. 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.

  19. A Post Licensing Study of Community Effects at Two Operating Nuclear Power Plants. Final Report.

    Science.gov (United States)

    Purdy, Bruce J.; And Others

    In an effort to identify and assess the social, economic, and political effects of nuclear power plant construction and operation upon two host communities (Plymouth, Massachusetts and Waterford, Connecticut), a post-licensing review revealed that the primary impact of the nuclear power plants in both communities was an increase in the property…

  20. Microbial community structure elucidates performance of Glyceria maxima plant microbial fuel cell

    NARCIS (Netherlands)

    Timmers, R.A.; Rothballer, M.; Strik, D.P.B.T.B.; Engel, M.; Schulz, M.; Hartmann, A.; Hamelers, H.V.M.; Buisman, C.J.N.

    2012-01-01

    The plant microbial fuel cell (PMFC) is a technology in which living plant roots provide electron donor, via rhizodeposition, to a mixed microbial community to generate electricity in a microbial fuel cell. Analysis and localisation of the microbial community is necessary for gaining insight into

  1. Corporate social responsibility along pipelines: communities and corporations working together

    Energy Technology Data Exchange (ETDEWEB)

    Carvalho, Edison D.R.; Lopes, Luciano E.; Danciguer, Lucilene; Macarini, Samuel; Souza, Maira de [Grupo de Aplicacao Interdisciplinar a Aprendizagem (GAIA), Campinas, SP (Brazil)

    2009-07-01

    In this paper we present GAIA's findings in three corporate social responsibility projects along pipelines owned by three Brazilian companies in gas, oil and mining sectors. The projects had as the main goal to improve the relationship with communities in the companies' direct influence areas. Clearly, the relationship with communities along pipelines is essential to prevent and reduce industrial hazards. The damage in pipelines due to agriculture, buildings, intentional perforations and traffic of heavy vehicles may cause fatal accidents, environmental and material losses. Such accidents have negative consequences with regard to economy, image and relationship with communities and environmental agencies. From communities' perspective, pipelines deteriorate their life quality due to risk of industrial hazards nearby their houses. The lack of proper information about the pipelines remarkably increases insecurity feelings and discourses against the companies among community leaders. The methodology developed by GAIA comprises companies' and communities' interests and encompasses nine stages. 1. Socio-environmental appraisal or inventory, mapping main risks, communities' needs and their leaders. 2. Communication plan, defining strategies, languages and communication vehicles for each stakeholder group. 3. Inter-institutional meetings to include other institutions in the program. 4. Launching seminar in partnership with local authorities, divulging companies' actions in the cities with pipelines. 5. Multiplier agents formation, enabling teachers, local leaders and government representatives to disseminate correct information about the pipelines such as their functioning, hazard prevention, maintenance actions, and restrictions of activities over the pipelines. 6. Formation on project management, enabling teachers, local leaders and government representatives to elaborate, fund raise and manage socio environmental projects aimed at

  2. Stomatal Blue Light Response Is Present in Early Vascular Plants.

    Science.gov (United States)

    Doi, Michio; Kitagawa, Yuki; Shimazaki, Ken-ichiro

    2015-10-01

    Light is a major environmental factor required for stomatal opening. Blue light (BL) induces stomatal opening in higher plants as a signal under the photosynthetic active radiation. The stomatal BL response is not present in the fern species of Polypodiopsida. The acquisition of a stomatal BL response might provide competitive advantages in both the uptake of CO2 and prevention of water loss with the ability to rapidly open and close stomata. We surveyed the stomatal opening in response to strong red light (RL) and weak BL under the RL with gas exchange technique in a diverse selection of plant species from euphyllophytes, including spermatophytes and monilophytes, to lycophytes. We showed the presence of RL-induced stomatal opening in most of these species and found that the BL responses operated in all euphyllophytes except Polypodiopsida. We also confirmed that the stomatal opening in lycophytes, the early vascular plants, is driven by plasma membrane proton-translocating adenosine triphosphatase and K(+) accumulation in guard cells, which is the same mechanism operating in stomata of angiosperms. These results suggest that the early vascular plants respond to both RL and BL and actively regulate stomatal aperture. We also found three plant species that absolutely require BL for both stomatal opening and photosynthetic CO2 fixation, including a gymnosperm, C. revoluta, and the ferns Equisetum hyemale and Psilotum nudum. © 2015 American Society of Plant Biologists. All Rights Reserved.

  3. Effects of plant diversity on primary production and species interactions in brackish water angiosperm communities

    DEFF Research Database (Denmark)

    Salo, Tiina; Gustafsson, Camilla; Boström, Christoffer

    2009-01-01

    Research on plant biodiversity and ecosystem functioning has mainly focused on terrestrial ecosystems, and our understanding of how plant species diversity and interactions affect processes in marine ecosystems is still limited. To investigate if plant species richness and composition influence...... plant productivity in brackish water angiosperm communities, a 14 wk field experiment was conducted. Using a replacement design with a standardized initial aboveground biomass, shoots of Zostera marina, Potamogeton filiformis and P. perfoliatus were planted on a shallow, sandy bottom in replicated...

  4. Climate Effects on Plant Range Distributions and Community Structure of Pacific Northwest Prairies

    Energy Technology Data Exchange (ETDEWEB)

    Bridgham, Scott D. [Univ. of Oregon, Eugene, OR (United States); Johnson, Bart [Univ. of Oregon, Eugene, OR (United States)

    2013-09-26

    was negatively impacted by increased temperatures, but for species planted north of their current range, increased temperature was neutral. However, for surviving plants climate treatments and site-specific factors (e.g., nutrient availability) were the strongest predictors of plant growth and seed set. When recruitment and plant growth are considered together, increased temperatures are negative within a species current range but beyond this range they become positive. Germination was the most critical stage for plant response across all sites and climate treatments. Our results underscore the importance of including plant vital rates into models that are examining climate change effects on plant ranges. Warming altered plant community composition, decreased diversity, and increased total cover, with warmed northern communities over time becoming more like ambient communities further south. In particular, warming increased the cover of annual introduced species, suggesting that the observed biogeographic pattern of increasing invasion by this plant functional group in US West Coast prairies as one moves further south is at least in part due to climate. Our results suggest that with the projected increase in drought severity with climate change, Pacific Northwest prairies may face an increase of invasion by annuals, similar to what has been observed in California, resulting in novel species assemblages and shifts in functional composition, which in turn may alter ecosystem function. Warming generally increased nutrient availability and plant productivity across all sites. The seasonality of soil respiration responses to heating were strongly dependent on the Mediterranean climate gradient in the PNW, with heating responses being generally positive during periods of adequate soil moisture and becoming neutral to negative during periods of low soil moisture. The asynchrony between temperature and precipitation may make soils less sensitive to warming. Precipitation

  5. ROLE OF ETHYLENE IN RESPONSES OF PLANTS TO NITROGEN AVAILABILITY

    Directory of Open Access Journals (Sweden)

    M Iqbal R Khan

    2015-10-01

    Full Text Available Ethylene is a plant hormone involved in several physiological processes and regulates the plant development during the whole life. Stressful conditions usually activate ethylene biosynthesis and signalling in plants. The availability of nutrients, shortage or excess, influences plant metabolism and ethylene plays an important role in plant adaptation under suboptimal conditions. Among the plant nutrients, the nitrogen (N is one the most important mineral element required for plant growth and development. The availability of N significantly influences plant metabolism, including ethylene biology. The interaction between ethylene and N affects several physiological process such as leaf gas exchanges, roots architecture, leaf, fruits and flowers development. Low plant N use efficiency leads to N loss and N deprivation, which affect ethylene biosynthesis and tissues sensitivity, inducing cell damage and ultimately lysis. Plants may respond differently to N availability balancing ethylene production through its signalling network. This review discusses the recent advances in the interaction between N availability and ethylene at whole plant and different organ levels, and explores how N availability induces ethylene biology and plant responses. Exogenously applied ethylene seems to cope the stress conditions and improves plant physiological performance. This can be explained considering the expression of ethylene biosynthesis and signalling genes under different N availability. A greater understanding of the regulation of N by means of ethylene modulation may help to increase N use efficiency and directly influence crop productivity under conditions of limited N availability, leading to positive effects on the environment. Moreover, efforts should be focused on the effect of N deficiency or excess in fruit trees, where ethylene can have detrimental effects especially during postharvest.

  6. Meteorological considerations in emergency response capability at nuclear power plant

    International Nuclear Information System (INIS)

    Fairobent, J.E.

    1985-01-01

    Meteorological considerations in emergency response at nuclear power plants are discussed through examination of current regulations and guidance documents, including discussion of the rationale for current regulatory requirements related to meteorological information for emergency response. Areas discussed include: major meteorological features important to emergency response; onsite meteorological measurements programs, including redundant and backup measurements; access to offsite sources of meteorological information; consideration of real-time and forecast conditions and atmospheric dispersion modeling

  7. Aquatic emergency response model at the Savannah River Plant

    International Nuclear Information System (INIS)

    Hayes, D.W.

    1987-01-01

    The Savannah River Plant emergency response plans include a stream/river emergency response model to predict travel times, maximum concentrations, and concentration distributions as a function of time at selected downstream/river locations from each of the major SRP installations. The menu driven model can be operated from any of the terminals that are linked to the real-time computer monitoring system for emergency response

  8. Links between plant and fungal communities across a deforestation chronosequence in the Amazon rainforest.

    Science.gov (United States)

    Mueller, Rebecca C; Paula, Fabiana S; Mirza, Babur S; Rodrigues, Jorge L M; Nüsslein, Klaus; Bohannan, Brendan J M

    2014-07-01

    Understanding the interactions among microbial communities, plant communities and soil properties following deforestation could provide insights into the long-term effects of land-use change on ecosystem functions, and may help identify approaches that promote the recovery of degraded sites. We combined high-throughput sequencing of fungal rDNA and molecular barcoding of plant roots to estimate fungal and plant community composition in soil sampled across a chronosequence of deforestation. We found significant effects of land-use change on fungal community composition, which was more closely correlated to plant community composition than to changes in soil properties or geographic distance, providing evidence for strong links between above- and below-ground communities in tropical forests.

  9. Changing expectations: a longitudinal study of community attitudes toward a nuclear power plant

    International Nuclear Information System (INIS)

    Hughey, J.B.; Lounsbury, J.W.; Sundstrom, E.; Mattingly, T.J. Jr.

    1983-01-01

    Initial and 5-year follow-up interviews were conducted with 213 residents of the host community for a nuclear power plant. The purpose was to determine possible changes in attitudes toward the plant and expectations about potential outcomes associated with construction. Large negative changes in attitudes toward the plant were noted and were accompanied most notably by decreased expectations of positive outcomes. The structure of the expectations remained essentially stable over the 5-year period. Perceptions of hazards, community disruption, and economic benefits as measured early in construction and during peak construction were found to be the best predictors of acceptance of the nuclear plant. Initial expectations were found to predict overall attitude toward the plant 5 years later. Results were discussed in terms of implications for social impact assessment, large-scale community change, and the predictability of community attitudes toward nuclear power plant construction

  10. Effects of diversity and identity of the neighbouring plant community on the abundance of arthropods on individual ragwort (Jacobaea vulgaris) plants

    NARCIS (Netherlands)

    Kostenko, O.; Grootemaat, Saskia S.; Van der Putten, W.H.; Bezemer, T.M.

    2012-01-01

    The diversity of plant community can greatly affect the abundance and diversity of arthropods associated to that community, but can also influence the composition or abundance of arthropods on individual plants growing in that community. We sampled arthropods and recorded plant size of individual

  11. Methodology for Assessment of Inertial Response from Wind Power Plants

    DEFF Research Database (Denmark)

    Altin, Müfit; Teodorescu, Remus; Bak-Jensen, Birgitte

    2012-01-01

    High wind power penetration levels result in additional requirements from wind power in order to improve frequency stability. Replacement of conventional power plants with wind power plants reduces the power system inertia due to the wind turbine technology. Consequently, the rate of change...... of frequency and the maximum frequency deviation increase after a disturbance such as generation loss, load increase, etc. Having no inherent inertial response, wind power plants need additional control concepts in order to provide an additional active power following a disturbance. Several control concepts...... have been implemented in the literature, but the assessment of these control concepts with respect to power system requirements has not been specified. In this paper, a methodology to assess the inertial response from wind power plants is proposed. Accordingly, the proposed methodology is applied...

  12. Interactions between plant hormones and heavy metals responses.

    Science.gov (United States)

    Bücker-Neto, Lauro; Paiva, Ana Luiza Sobral; Machado, Ronei Dorneles; Arenhart, Rafael Augusto; Margis-Pinheiro, Marcia

    2017-01-01

    Heavy metals are natural non-biodegradable constituents of the Earth's crust that accumulate and persist indefinitely in the ecosystem as a result of human activities. Since the industrial revolution, the concentration of cadmium, arsenic, lead, mercury and zinc, amongst others, have increasingly contaminated soil and water resources, leading to significant yield losses in plants. These issues have become an important concern of scientific interest. Understanding the molecular and physiological responses of plants to heavy metal stress is critical in order to maximize their productivity. Recent research has extended our view of how plant hormones can regulate and integrate growth responses to various environmental cues in order to sustain life. In the present review we discuss current knowledge about the role of the plant growth hormones abscisic acid, auxin, brassinosteroid and ethylene in signaling pathways, defense mechanisms and alleviation of heavy metal toxicity.

  13. Interactions between plant hormones and heavy metals responses

    Directory of Open Access Journals (Sweden)

    Lauro Bücker-Neto

    2017-04-01

    Full Text Available Abstract Heavy metals are natural non-biodegradable constituents of the Earth's crust that accumulate and persist indefinitely in the ecosystem as a result of human activities. Since the industrial revolution, the concentration of cadmium, arsenic, lead, mercury and zinc, amongst others, have increasingly contaminated soil and water resources, leading to significant yield losses in plants. These issues have become an important concern of scientific interest. Understanding the molecular and physiological responses of plants to heavy metal stress is critical in order to maximize their productivity. Recent research has extended our view of how plant hormones can regulate and integrate growth responses to various environmental cues in order to sustain life. In the present review we discuss current knowledge about the role of the plant growth hormones abscisic acid, auxin, brassinosteroid and ethylene in signaling pathways, defense mechanisms and alleviation of heavy metal toxicity.

  14. A role for SR proteins in plant stress responses.

    Science.gov (United States)

    Duque, Paula

    2011-01-01

    Members of the SR (serine/arginine-rich) protein gene family are key players in the regulation of alternative splicing, an important means of generating proteome diversity and regulating gene expression. In plants, marked changes in alternative splicing are induced by a wide variety of abiotic stresses, suggesting a role for this highly versatile gene regulation mechanism in the response to environmental cues. In support of this notion, the expression of plant SR proteins is stress-regulated at multiple levels, with environmental signals controlling their own alternative splicing patterns, phosphorylation status and subcellular distribution. Most importantly, functional links between these RNA-binding proteins and plant stress tolerance are beginning to emerge, including a role in the regulation of abscisic acid (ABA) signaling. Future identification of the physiological mRNA targets of plant SR proteins holds much promise for the elucidation of the molecular mechanisms underlying their role in the response to abiotic stress.

  15. Principal response curves: analysis of time-dependent multivariate responses of biological community to stress

    NARCIS (Netherlands)

    Brink, van den P.J.; Braak, ter C.J.F.

    1999-01-01

    In this paper a novel multivariate method is proposed for the analysis of community response data from designed experiments repeatedly sampled in time. The long-term effects of the insecticide chlorpyrifos on the invertebrate community and the dissolved oxygen (DO)–pH–alkalinity–conductivity

  16. Responses of lichen communities to 18 years of natural and experimental warming.

    Science.gov (United States)

    Alatalo, Juha M; Jägerbrand, Annika K; Chen, Shengbin; Molau, Ulf

    2017-07-01

    Climate change is expected to have major impacts on high alpine and arctic ecosystems in the future, but empirical data on the impact of long-term warming on lichen diversity and richness are sparse. This study report the effects of 18 years of ambient and experimental warming on lichens and vascular plant cover in two alpine plant communities, a dry heath with sparse canopy cover (54 %) and a mesic meadow with a more developed (67 %) canopy cover, in sub-arctic Sweden. The effects of long-term passive experimental warming using open top chambers (OTCs) on lichens and total vascular plant cover, and the impact of plant cover on lichen community parameters, were analysed. Between 1993 and 2013, mean annual temperature increased about 2 °C. Both site and experimental warming had a significant effect on cover, species richness, effective number of species evenness of lichens, and total plant canopy cover. Lichen cover increased in the heath under ambient conditions, and remained more stable under experimental warming. The negative effect on species richness and effective number of species was driven by a decrease in lichens under experimental warming in the meadow. Lichen cover, species richness, effective number of species evenness were negatively correlated with plant canopy cover. There was a significant negative impact on one species and a non-significant tendency of lower abundance of the most common species in response to experimental warming. The results from the long-term warming study imply that arctic and high alpine lichen communities are likely to be negatively affected by climate change and an increase in plant canopy cover. Both biotic and abiotic factors are thus important for future impacts of climate change on lichens. © The Author 2017. Published by Oxford University Press on behalf of the Annals of Botany Company. All rights reserved. For Permissions, please email: journals.permissions@oup.com

  17. A "community as resource" strategy for disaster response.

    OpenAIRE

    Lichterman, J D

    2000-01-01

    Natural and technological disasters present significant threats to the public's health. The emergency response capabilities of government and private relief organizations are limited. With a strategy in which residents of urban areas are trained in search and rescue, first aid, fire suppression, care and shelter, emergency communications, and disaster mental health, the community becomes a "resource" rather than a "victim."

  18. Facilitating Student Engagement: Social Responsibility and Freshmen Learning Communities

    Science.gov (United States)

    Kingston, Lindsey N.; MacCartney, Danielle; Miller, Andrea

    2014-01-01

    Human rights education is advanced as a method for promoting social responsibility, with an emphasis on promoting ideals of "global citizenship" among undergraduate students. At the same time, the practice of learning communities is widespread on college campuses for retaining freshmen and promoting student success. However, there is…

  19. Soil microbial community response to land use and various soil ...

    African Journals Online (AJOL)

    Soil microbial community response to land use and various soil elements in a city landscape of north China. ... African Journal of Biotechnology ... Legumes played an important role in stimulating the growth and reproduction of various soil microbial populations, accordingly promoting the microbial catabolic activity.

  20. Democracy, Community, Responsibility, and Influence in Teacher Education.

    Science.gov (United States)

    Chamberlin, C.; Sawada, Daiyo

    1987-01-01

    This paper examines a large undergraduate teacher education program which had as a major goal allaying students' feelings of depersonalization and alienation. Specifically looked at are: (1) processes leading to a sense of community, responsibility, and influence among students and staff and (2) processes countering such development. (Author/MT)

  1. The role of biotic interactions in plant community assembly: What is the community species pool?

    Science.gov (United States)

    Švamberková, Eva; Vítová, Alena; Lepš, Jan

    2017-11-01

    Differences in plant species composition between a community and its species pool are considered to reflect the effect of community filters. If we define the species pool as a set of species able to reach a site and form a viable population in a given abiotic environment (i.e. to pass the dispersal and abiotic filter), the difference in species composition should correspond to the effect of biotic interactions. However, most of the operational definitions of the species pool are based on co-occurrence patterns and thus also reflect the effect of biotic relationships, including definitions based on functional plant traits, Ellenberg indicator values or Beals index. We conducted two seed introduction experiments in an oligotrophic wet meadow with the aim of demonstrating that many species excluded, according to the above definitions, from a species pool are in fact able to establish there successfully if competition is removed. In sowing experiments, we studied the establishment and survival of species after the removal of competition (i.e. in artificial gaps) and in intact vegetation. We also investigated inter-annual variability of seed germination and seedling establishment and competitive exclusion of sown species. The investigated species also included those from very different habitats (i.e. species with very low corresponding Beals index or Ellenberg indicator values that were different from the target community weighted mean). Many of these species were able to grow in the focal wet meadow if competition was removed, but they did not establish and survive in the intact community. These species are thus not limited by abiotic conditions, but by the biotic filter. We also recorded a great inter-annual variability in seed germination and seedling establishment. Competitive exclusion of species with different ecological requirements could be quite fast (one and half seasons) in some species, but some non-resident species were able to survive several seasons; the

  2. Influences of Plant Species, Season and Location on Leaf Endophytic Bacterial Communities of Non-Cultivated Plants.

    Science.gov (United States)

    Ding, Tao; Melcher, Ulrich

    2016-01-01

    Bacteria are known to be associated endophytically with plants. Research on endophytic bacteria has identified their importance in food safety, agricultural production and phytoremediation. However, the diversity of endophytic bacterial communities and the forces that shape their compositions in non-cultivated plants are largely uncharacterized. In this study, we explored the diversity, community structure, and dynamics of endophytic bacteria in different plant species in the Tallgrass Prairie Preserve of northern Oklahoma, USA. High throughput sequencing of amplified segments of bacterial rDNA from 81 samples collected at four sampling times from five plant species at four locations identified 335 distinct OTUs at 97% sequence similarity, representing 16 phyla. Proteobacteria was the dominant phylum in the communities, followed by the phyla Bacteriodetes and Actinobacteria. Bacteria from four classes of Proteobacteria were detected with Alphaproteobacteria as the dominant class. Analysis of molecular variance revealed that host plant species and collecting date had significant influences on the compositions of the leaf endophytic bacterial communities. The proportion of Alphaproteobacteria was much higher in the communities from Asclepias viridis than from other plant species and differed from month to month. The most dominant bacterial groups identified in LDA Effect Size analysis showed host-specific patterns, indicating mutual selection between host plants and endophytic bacteria and that leaf endophytic bacterial compositions were dynamic, varying with the host plant's growing season in three distinct patterns. In summary, next generation sequencing has revealed variations in the taxonomic compositions of leaf endophytic bacterial communities dependent primarily on the nature of the plant host species.

  3. Influences of Plant Species, Season and Location on Leaf Endophytic Bacterial Communities of Non-Cultivated Plants.

    Directory of Open Access Journals (Sweden)

    Tao Ding

    Full Text Available Bacteria are known to be associated endophytically with plants. Research on endophytic bacteria has identified their importance in food safety, agricultural production and phytoremediation. However, the diversity of endophytic bacterial communities and the forces that shape their compositions in non-cultivated plants are largely uncharacterized. In this study, we explored the diversity, community structure, and dynamics of endophytic bacteria in different plant species in the Tallgrass Prairie Preserve of northern Oklahoma, USA. High throughput sequencing of amplified segments of bacterial rDNA from 81 samples collected at four sampling times from five plant species at four locations identified 335 distinct OTUs at 97% sequence similarity, representing 16 phyla. Proteobacteria was the dominant phylum in the communities, followed by the phyla Bacteriodetes and Actinobacteria. Bacteria from four classes of Proteobacteria were detected with Alphaproteobacteria as the dominant class. Analysis of molecular variance revealed that host plant species and collecting date had significant influences on the compositions of the leaf endophytic bacterial communities. The proportion of Alphaproteobacteria was much higher in the communities from Asclepias viridis than from other plant species and differed from month to month. The most dominant bacterial groups identified in LDA Effect Size analysis showed host-specific patterns, indicating mutual selection between host plants and endophytic bacteria and that leaf endophytic bacterial compositions were dynamic, varying with the host plant's growing season in three distinct patterns. In summary, next generation sequencing has revealed variations in the taxonomic compositions of leaf endophytic bacterial communities dependent primarily on the nature of the plant host species.

  4. Real-time information support for managing plant emergency responses

    International Nuclear Information System (INIS)

    Cain, D.G.; Lord, R.J.; Wilkinson, C.D.

    1983-01-01

    The Three Mile Island Unit 2 accident highlighted the need to develop a systematic approach to managing plant emergency responses, to identify a better decision-making process, and to implement real-time information support for decision-making. The overall process management function is described and general information requirements for management of plant emergencies are identified. Basic information systems are being incorporated and future extensions and problem areas are discussed. (U.K.)

  5. Microbial community structure elucidates performance of Glyceria maxima plant microbial fuel cell

    OpenAIRE

    Timmers, R.A.; Rothballer, M.; Strik, D.P.B.T.B.; Engel, M.; Schulz, M.; Hartmann, A.; Hamelers, H.V.M.; Buisman, C.J.N.

    2012-01-01

    The plant microbial fuel cell (PMFC) is a technology in which living plant roots provide electron donor, via rhizodeposition, to a mixed microbial community to generate electricity in a microbial fuel cell. Analysis and localisation of the microbial community is necessary for gaining insight into the competition for electron donor in a PMFC. This paper characterises the anode-rhizosphere bacterial community of a Glyceria maxima (reed mannagrass) PMFC. Electrochemically active bacteria (EAB) w...

  6. Microbial community structure elucidates performance of Glyceria maxima plant microbial fuel cell

    OpenAIRE

    Timmers, Ruud A.; Rothballer, Michael; Strik, David P. B. T. B.; Engel, Marion; Schulz, Stephan; Schloter, Michael; Hartmann, Anton; Hamelers, Bert; Buisman, Cees

    2012-01-01

    The plant microbial fuel cell (PMFC) is a technology in which living plant roots provide electron donor, via rhizodeposition, to a mixed microbial community to generate electricity in a microbial fuel cell. Analysis and localisation of the microbial community is necessary for gaining insight into the competition for electron donor in a PMFC. This paper characterises the anode–rhizosphere bacterial community of a Glyceria maxima (reed mannagrass) PMFC. Electrochemically active bacteria (EAB) w...

  7. Transcriptional plant responses critical for resistance towards necrotrophic pathogens

    Directory of Open Access Journals (Sweden)

    Rainer P. Birkenbihl

    2011-11-01

    Full Text Available Plant defenses aimed at necrotrophic pathogens appear to be genetically complex. Despite the apparent lack of a specific recognition of such necrotrophs by products of major R genes, biochemical, molecular, and genetic studies, in particular using the model plant Arabidopsis, have uncovered numerous host components critical for the outcome of such interactions. Although the JA signaling pathway plays a central role in plant defense towards necrotrophs additional signaling pathways contribute to the plant response network. Transcriptional reprogramming is a vital part of the host defense machinery and several key regulators have recently been identified. Some of these transcription factors positively affect plant resistance whereas others play a role in enhancing host susceptibility towards these phytopathogens.

  8. ‘Omics’ and Plant Responses to Botrytis cinerea

    Directory of Open Access Journals (Sweden)

    Synan F. AbuQamar

    2016-11-01

    Full Text Available Botrytis cinerea is a dangerous plant pathogenic fungus with wide host ranges. This aggressive pathogen uses multiple weapons to invade and cause serious damages on its host plants. The continuing efforts of how to solve the puzzle of the multigenic nature of B. cinerea’s pathogenesis and plant defense mechanisms against the disease caused by this mold, the integration of omic approaches, including genomics, transcriptomics, proteomics and metabolomics, along with functional analysis could be a potential solution. Omic studies will provide a foundation for development of genetic manipulation and breeding programs that will eventually lead to crop improvement and protection. In this mini-review, we will highlight the current progresses in research in plant stress responses to B. cinerea using high-throughput omic technologies. We also discuss the opportunities that omic technologies can provide to research on B. cinerea-plant interactions as an example showing the impacts of omics on agricultural research.

  9. Broad-Scale Comparison of Photosynthesis in Terrestrial and Aquatic Plant Communities

    DEFF Research Database (Denmark)

    Sand-Jensen, Kaj; Krause-Jensen, D.

    1997-01-01

    Comparisons of photosynthesis in terrestrial and aquatic habitats have been impaired by differences in methods and time-scales of measurements. We compiled information on gross photosynthesis at high irradiance and photosynthetic efficiency at low irradiance from 109 published terrestrial studies...... communities probably due to more efficient light utilization and gas exchange in the terrestrial habitats. By contrast only small differences were found within different aquatic plant communities or within different terrestrial plant communities....... of forests, grasslands and crops and 319 aquatic studies of phytoplankton, macrophyte and attached microalgal communities to test if specific differences existed between the communities. Maximum gross photosynthesis and photosynthetic efficiency were systematically higher in terrestrial than in aquatic...

  10. Changes in uranium plant community leaders' attitudes toward nuclear power: before and after TMI

    International Nuclear Information System (INIS)

    Winfield-Laird, I.; Hastings, M.; Cawley, M.E.

    1982-01-01

    The results of an investigation of the reactions of community leaders in nuclear power plant host communities toward nuclear power following the accident at Three Mile Island (TMI) are reported. Public and private sector officials were surveyed in ten general areas covering their attitudes toward and the continued use of nuclear power as compared to other fuel types, and the reassessment of the local plant impact on different community groups and aspects of community life. Information is compared with findings from a similar study conducted with the same community leaders prior to the TMI accident. The results indicate that community leaders' attitudes remained highly favorable toward the continued use of nuclear power. Three-fourths of the sample indicated that they would probably or definitely allow the continued use of nuclear power as compared to other fuel types, and the reassessment of the local majority still view the plant presence as having a positive impact on their communities. (author)

  11. Recent Molecular Advances on Downstream Plant Responses to Abiotic Stress

    Directory of Open Access Journals (Sweden)

    Cláudia Regina Batista de Souza

    2012-07-01

    Full Text Available Abiotic stresses such as extremes of temperature and pH, high salinity and drought, comprise some of the major factors causing extensive losses to crop production worldwide. Understanding how plants respond and adapt at cellular and molecular levels to continuous environmental changes is a pre-requisite for the generation of resistant or tolerant plants to abiotic stresses. In this review we aimed to present the recent advances on mechanisms of downstream plant responses to abiotic stresses and the use of stress-related genes in the development of genetically engineered crops.

  12. Plant responsiveness to root-root communication of stress cues.

    Science.gov (United States)

    Falik, Omer; Mordoch, Yonat; Ben-Natan, Daniel; Vanunu, Miriam; Goldstein, Oron; Novoplansky, Ariel

    2012-07-01

    Phenotypic plasticity is based on the organism's ability to perceive, integrate and respond to multiple signals and cues informative of environmental opportunities and perils. A growing body of evidence demonstrates that plants are able to adapt to imminent threats by perceiving cues emitted from their damaged neighbours. Here, the hypothesis was tested that unstressed plants are able to perceive and respond to stress cues emitted from their drought- and osmotically stressed neighbours and to induce stress responses in additional unstressed plants. Split-root Pisum sativum, Cynodon dactylon, Digitaria sanguinalis and Stenotaphrum secundatum plants were subjected to osmotic stress or drought while sharing one of their rooting volumes with an unstressed neighbour, which in turn shared its other rooting volume with additional unstressed neighbours. Following the kinetics of stomatal aperture allowed testing for stress responses in both the stressed plants and their unstressed neighbours. In both P. sativum plants and the three wild clonal grasses, infliction of osmotic stress or drought caused stomatal closure in both the stressed plants and in their unstressed neighbours. While both continuous osmotic stress and drought induced prolonged stomatal closure and limited acclimation in stressed plants, their unstressed neighbours habituated to the stress cues and opened their stomata 3-24 h after the beginning of stress induction. The results demonstrate a novel type of plant communication, by which plants might be able to increase their readiness to probable future osmotic and drought stresses. Further work is underway to decipher the identity and mode of operation of the involved communication vectors and to assess the potential ecological costs and benefits of emitting and perceiving drought and osmotic stress cues under various ecological scenarios.

  13. Genetics-based interactions among plants, pathogens, and herbivores define arthropod community structure.

    Science.gov (United States)

    Busby, Posy E; Lamit, Louis J; Keith, Arthur R; Newcombe, George; Gehring, Catherine A; Whitham, Thomas G; Dirzo, Rodolfo

    2015-07-01

    Plant resistance to pathogens or insect herbivores is common, but its potential for indirectly influencing plant-associated communities is poorly known. Here, we test whether pathogens' indirect effects on arthropod communities and herbivory depend on plant resistance to pathogens and/or herbivores, and address the overarching interacting foundation species hypothesis that genetics-based interactions among a few highly interactive species can structure a much larger community. In a manipulative field experiment using replicated genotypes of two Populus species and their interspecific hybrids, we found that genetic variation in plant resistance to both pathogens and insect herbivores modulated the strength of pathogens' indirect effects on arthropod communities and insect herbivory. First, due in part to the pathogens' differential impacts on leaf biomass among the two Populus species and the hybrids, the pathogen most strongly impacted arthropod community composition, richness, and abundance on the pathogen-susceptible tree species. Second, we found similar patterns comparing pathogen-susceptible and pathogen-resistant genotypes within species. Third, within a plant species, pathogens caused a fivefold greater reduction in herbivory on insect-herbivore-susceptible plant genotypes than on herbivore-resistant genotypes, demonstrating that the pathogen-herbivore interaction is genotype dependent. We conclude that interactions among plants, pathogens, and herbivores can structure multitrophic communities, supporting the interacting foundation species hypothesis. Because these interactions are genetically based, evolutionary changes in genetic resistance could result in ecological changes in associated communities, which may in turn feed back to affect plant fitness.

  14. Temporal dynamics of soil nematode communities in a grassland plant diversity experiment.

    NARCIS (Netherlands)

    Viketoft, M.; Sohlenius, B.; Bostrom, S.; Palmborg, C.; Bengtsson, J.; Berg, M.P.; Kuss-Danell, K.

    2011-01-01

    We report here on an 8-year study examining links between plant and nematode communities in a grassland plant diversity experiment, located in the north of Sweden on previous agricultural soil. The examined plots contained 1, 4 and 12 common grassland plant species from three functional groups;

  15. Long-term effects of plant diversity and composition on soil nematode communities in grassland.

    NARCIS (Netherlands)

    Viketoft, M.; Bengtsson, J.; Sohlenius, B.; Berg, M.P.; Petchey, O.; Palmborg, C.; Huss-Daniel, K.

    2009-01-01

    An important component of plant-soil feedbacks is how plant species identity and diversity influence soil organism communities. We examine the effects of grassland plant species growing alone and together up to a richness of 12 species on nematode diversity and feeding group composition, eight years

  16. Comparing arbuscular mycorrhizal communities of individual plants in a grassland biodiversity experiment

    NARCIS (Netherlands)

    Van de Voorde, T.F.J.; Van der Putten, W.H.; Gamper, H.A.; Hol, W.H.G.; Bezemer, T.M.

    2010-01-01

    Plants differ greatly in the soil organisms colonizing their roots. However, how soil organism assemblages of individual plant roots can be influenced by plant community properties remains poorly understood. We determined the composition of arbuscular mycorrhizal fungi (AMF) in Jacobaea vulgaris

  17. Fire and invasive exotic plant species in eastern oak communities: an assessment of current knowledge

    Science.gov (United States)

    Cynthia D. Huebner

    2006-01-01

    Successful regeneration of oak-dominated communities in the Eastern United States historically requires disturbance such as fire, making them vulnerable to invasion by exotic plants. Little is currently known about the effects of fire on invasive plant species and the effects of invasive plant species on fire regimes of this region. Seventeen common eastern invaders...

  18. Interspecific Plant Interactions Reflected in Soil Bacterial Community Structure and Nitrogen Cycling in Primary Succession.

    Science.gov (United States)

    Knelman, Joseph E; Graham, Emily B; Prevéy, Janet S; Robeson, Michael S; Kelly, Patrick; Hood, Eran; Schmidt, Steve K

    2018-01-01

    Past research demonstrating the importance plant-microbe interactions as drivers of ecosystem succession has focused on how plants condition soil microbial communities, impacting subsequent plant performance and plant community assembly. These studies, however, largely treat microbial communities as a black box. In this study, we sought to examine how emblematic shifts from early successional Alnus viridus ssp. sinuata (Sitka alder) to late successional Picea sitchensis (Sitka spruce) in primary succession may be reflected in specific belowground changes in bacterial community structure and nitrogen cycling related to the interaction of these two plants. We examined early successional alder-conditioned soils in a glacial forefield to delineate how alders alter the soil microbial community with increasing dominance. Further, we assessed the impact of late-successional spruce plants on these early successional alder-conditioned microbiomes and related nitrogen cycling through a leachate addition microcosm experiment. We show how increasingly abundant alder select for particular bacterial taxa. Additionally, we found that spruce leachate significantly alters the composition of these microbial communities in large part by driving declines in taxa that are enriched by alder, including bacterial symbionts. We found these effects to be spruce specific, beyond a general leachate effect. Our work also demonstrates a unique influence of spruce on ammonium availability. Such insights bolster theory relating the importance of plant-microbe interactions with late-successional plants and interspecific plant interactions more generally.

  19. A mesocosm approach for detecting stream invertebrate community responses to treated wastewater effluent

    International Nuclear Information System (INIS)

    Grantham, Theodore E.; Cañedo-Argüelles, Miguel; Perrée, Isabelle; Rieradevall, Maria; Prat, Narcís

    2012-01-01

    The discharge of wastewater from sewage treatment plants is one of the most common forms of pollution to river ecosystems, yet the effects on aquatic invertebrate assemblages have not been investigated in a controlled experimental setting. Here, we use a mesocosm approach to evaluate community responses to exposure to different concentrations of treated wastewater effluents over a two week period. Multivariate analysis using Principal Response Curves indicated a clear, dose-effect response to the treatments, with significant changes in macroinvertebrate assemblages after one week when exposed to 30% effluent, and after two weeks in the 15% and 30% effluent treatments. Treatments were associated with an increase in nutrient concentrations (ammonium, sulfate, and phosphate) and reduction of dissolved oxygen. These findings indicate that exposure to wastewater effluent cause significant changes in abundance and composition of macroinvertebrate taxa and that effluent concentration as low as 5% can have detectable ecological effects. - Highlights: ► Stream invertebrate communities are altered by exposure to wastewater effluent. ► Principal Response Curves indicate a dose-effect response to effluent treatment. ► Biotic quality indices decline with increasing effluent concentration and exposure time. ► Effluent concentrations as low as 5% have detectable ecological effects. - Exposure to treated effluent in a stream mesocosm caused a dose-dependent response in the aquatic invertebrate community and led to declines in biological quality indices.

  20. Responses of riparian reptile communities to damming and urbanization

    Science.gov (United States)

    Hunt, Stephanie D.; Guzy, Jacquelyn C.; Price, Steven J.; Halstead, Brian J.; Eskew, Evan A.; Dorcas, Michael E.

    2013-01-01

    Various anthropogenic pressures, including habitat loss, threaten reptile populations worldwide. Riparian zones are critical habitat for many reptile species, but these habitats are also frequently modified by anthropogenic activities. Our study investigated the effects of two riparian habitat modifications-damming and urbanization-on overall and species-specific reptile occupancy patterns. We used time-constrained search techniques to compile encounter histories for 28 reptile species at 21 different sites along the Broad and Pacolet Rivers of South Carolina. Using a hierarchical Bayesian analysis, we modeled reptile occupancy responses to a site's distance upstream from dam, distance downstream from dam, and percent urban land use. The mean occupancy response by the reptile community indicated that reptile occupancy and species richness were maximized when sites were farther upstream from dams. Species-specific occupancy estimates showed a similar trend of lower occupancy immediately upstream from dams. Although the mean occupancy response of the reptile community was positively related to distance downstream from dams, the occupancy response to distance downstream varied among species. Percent urban land use had little effect on the occupancy response of the reptile community or individual species. Our results indicate that the conditions of impoundments and subsequent degradation of the riparian zones upstream from dams may not provide suitable habitat for a number of reptile species.

  1. Characterizing changes in soil bacterial community structure in response to short-term warming

    Energy Technology Data Exchange (ETDEWEB)

    Xiong, Jinbo [State Key Laboratory of Soil and Sustainable Agriculture, Institute of Soil Science, Chinese Academy of Sciences, Nanjing China; School of Marine Sciences, Ningbo University, Ningbo China; Sun, Huaibo [State Key Laboratory of Soil and Sustainable Agriculture, Institute of Soil Science, Chinese Academy of Sciences, Nanjing China; Peng, Fei [Key Laboratory of Desert and Desertification, Cold and Arid Regions Environmental and Engineering Research Institute, Chinese Academy of Sciences, Lanzhou China; Zhang, Huayong [State Key Laboratory of Soil and Sustainable Agriculture, Institute of Soil Science, Chinese Academy of Sciences, Nanjing China; Xue, Xian [Key Laboratory of Desert and Desertification, Cold and Arid Regions Environmental and Engineering Research Institute, Chinese Academy of Sciences, Lanzhou China; Gibbons, Sean M. [Argonne National Laboratory Biosciences Division, Argonne IL USA; Graduate Program in Biophysical Sciences, University of Chicago, Chicago IL USA; Gilbert, Jack A. [Argonne National Laboratory Biosciences Division, Argonne IL USA; Department of Ecology and Evolution, University of Chicago, Chicago IL USA; Chu, Haiyan [State Key Laboratory of Soil and Sustainable Agriculture, Institute of Soil Science, Chinese Academy of Sciences, Nanjing China

    2014-02-18

    High altitude alpine meadows are experiencing considerably greater than average increases in soil surface temperature, potentially as a result of ongoing climate change. The effects of warming on plant productivity and soil edaphic variables have been established previously, but the influence of warming on soil microbial community structure has not been well characterized. Here, the impact of 15 months of soil warming (both + 1 and + 2 degrees C) on bacterial community structure was examined in a field experiment on a Tibetan plateau alpine meadow using bar-coded pyrosequencing. Warming significantly changed (P < 0.05) the structure of the soil bacterial community, but the alpha diversity was not dramatically affected. Changes in the abundance of the Actinobacteria and Alphaproteobacteria were found to contribute the most to differences between ambient (AT) and artificially warmed conditions. A variance partitioning analysis (VPA) showed that warming directly explained 7.15% variation in bacterial community structure, while warming-induced changes in soil edaphic and plant phenotypic properties indirectly accounted for 28.3% and 20.6% of the community variance, respectively. Interestingly, certain taxa showed an inconsistent response to the two warming treatments, for example Deltaproteobacteria showed a decreased relative abundance at + 1 degrees C, but a return to AT control relative abundance at + 2 degrees C. This suggests complex microbial dynamics that could result from conditional dependencies between bacterial taxa.

  2. Coral community response to bleaching on a highly disturbed reef.

    Science.gov (United States)

    Guest, J R; Low, J; Tun, K; Wilson, B; Ng, C; Raingeard, D; Ulstrup, K E; Tanzil, J T I; Todd, P A; Toh, T C; McDougald, D; Chou, L M; Steinberg, P D

    2016-02-15

    While many studies of coral bleaching report on broad, regional scale responses, fewer examine variation in susceptibility among coral taxa and changes in community structure, before, during and after bleaching on individual reefs. Here we report in detail on the response to bleaching by a coral community on a highly disturbed reef site south of mainland Singapore before, during and after a major thermal anomaly in 2010. To estimate the capacity for resistance to thermal stress, we report on: a) overall bleaching severity during and after the event, b) differences in bleaching susceptibility among taxa during the event, and c) changes in coral community structure one year before and after bleaching. Approximately two thirds of colonies bleached, however, post-bleaching recovery was quite rapid and, importantly, coral taxa that are usually highly susceptible were relatively unaffected. Although total coral cover declined, there was no significant change in coral taxonomic community structure before and after bleaching. Several factors may have contributed to the overall high resistance of corals at this site including Symbiodinium affiliation, turbidity and heterotrophy. Our results suggest that, despite experiencing chronic anthropogenic disturbances, turbid shallow reef communities may be remarkably resilient to acute thermal stress.

  3. Inoculation effects on root-colonizing arbuscular mycorrhizal fungal communities spread beyond directly inoculated plants.

    Directory of Open Access Journals (Sweden)

    Martina Janoušková

    Full Text Available Inoculation with arbuscular mycorrhizal fungi (AMF may improve plant performance at disturbed sites, but inoculation may also suppress root colonization by native AMF and decrease the diversity of the root-colonizing AMF community. This has been shown for the roots of directly inoculated plants, but little is known about the stability of inoculation effects, and to which degree the inoculant and the inoculation-induced changes in AMF community composition spread into newly emerging seedlings that were not in direct contact with the introduced propagules. We addressed this topic in a greenhouse experiment based on the soil and native AMF community of a post-mining site. Plants were cultivated in compartmented pots with substrate containing the native AMF community, where AMF extraradical mycelium radiating from directly inoculated plants was allowed to inoculate neighboring plants. The abundances of the inoculated isolate and of native AMF taxa were monitored in the roots of the directly inoculated plants and the neighboring plants by quantitative real-time PCR. As expected, inoculation suppressed root colonization of the directly inoculated plants by other AMF taxa of the native AMF community and also by native genotypes of the same species as used for inoculation. In the neighboring plants, high abundance of the inoculant and the suppression of native AMF were maintained. Thus, we demonstrate that inoculation effects on native AMF propagate into plants that were not in direct contact with the introduced inoculum, and are therefore likely to persist at the site of inoculation.

  4. Inoculation effects on root-colonizing arbuscular mycorrhizal fungal communities spread beyond directly inoculated plants

    Science.gov (United States)

    Krak, Karol; Vosátka, Miroslav; Püschel, David; Štorchová, Helena

    2017-01-01

    Inoculation with arbuscular mycorrhizal fungi (AMF) may improve plant performance at disturbed sites, but inoculation may also suppress root colonization by native AMF and decrease the diversity of the root-colonizing AMF community. This has been shown for the roots of directly inoculated plants, but little is known about the stability of inoculation effects, and to which degree the inoculant and the inoculation-induced changes in AMF community composition spread into newly emerging seedlings that were not in direct contact with the introduced propagules. We addressed this topic in a greenhouse experiment based on the soil and native AMF community of a post-mining site. Plants were cultivated in compartmented pots with substrate containing the native AMF community, where AMF extraradical mycelium radiating from directly inoculated plants was allowed to inoculate neighboring plants. The abundances of the inoculated isolate and of native AMF taxa were monitored in the roots of the directly inoculated plants and the neighboring plants by quantitative real-time PCR. As expected, inoculation suppressed root colonization of the directly inoculated plants by other AMF taxa of the native AMF community and also by native genotypes of the same species as used for inoculation. In the neighboring plants, high abundance of the inoculant and the suppression of native AMF were maintained. Thus, we demonstrate that inoculation effects on native AMF propagate into plants that were not in direct contact with the introduced inoculum, and are therefore likely to persist at the site of inoculation. PMID:28738069

  5. Litter Accumulation and Nutrient Content of Roadside Plant Communities in Sichuan Basin, China.

    Science.gov (United States)

    He, Huiqin; Monaco, Thomas

    2017-08-30

    It is widely recognized that feedbacks exist between plant litter and plant community species composition, but this relationship is difficult to interpret over heterogeneous conditions typical of modified environments such as roadways. Given the need to expedite natural recovery of disturbed areas through restoration interventions, we characterized litter accumulation and nutrient content (i.e., organic carbon, total N, and P) and quantified their association with key plant species. Plant species cover and litter characteristics were sampled at 18 successional forest plant communities along major roadways in Sichuan Basin, western China. Variation in litter across communities was assessed with principal component analysis (PCA) and species with the highest correlation to PCA axes were determined with Pearson's r coefficients. Plant communities with the longest time since road construction (i.e., 70 years) were distinctly different in litter total N and organic carbon compared to plant communities with a shorter disturbance history. We encountered 59 plant species across sampling plots, but only four rare species (i.e., frequency plant litter across heavily disturbed landscapes and how litter characteristics and rare plant species are correlated.

  6. Microbial Community Activity And Plant Biomass Are Insensitive To Passive Warming In A Semiarid Ecosystem

    Science.gov (United States)

    Espinosa, N. J.; Fehmi, J. S.; Rasmussen, C.; Gallery, R. E.

    2017-12-01

    Soil microorganisms drive biogeochemical and nutrient cycling through the production of extracellular enzymes that facilitate organic matter decomposition and the flux of large amounts of carbon dioxide to the atmosphere. Although dryland ecosystems occupy over 40% of land cover and are projected to expand due to climate change, much of our current understanding of these processes comes from mesic temperate ecosystems. Understanding the responses of these globally predominant dryland ecosystems is therefore important yet complicated by co-occurring environmental changes. For example, the widespread and pervasive transition from grass to woody dominated landscapes is changing the hydrology, fire regimes, and carbon storage potential of semiarid ecosystems. In this study, we used a novel passive method of warming to conduct a warming experiment with added plant debris as either woodchip or biochar, to simulate different long-term carbon additions that accompany woody plant encroachment in semiarid ecosystems. The response of heterotrophic respiration, plant biomass, and microbial activity was monitored bi-annually. We hypothesized that the temperature manipulations would have direct and indirect effects on microbial activity. Warmer soils directly reduce the activity of soil extracellular enzymes through denaturation and dehydration of soil pores and indirectly through reducing microbe-available substrates and plant inputs. Overall, reduction in extracellular enzyme activity may reduce decomposition of coarse woody debris and potentially enhance soil carbon storage in semiarid ecosystems. For all seven hydrolytic enzymes examined as well as heterotrophic respiration, there was no consistent or significant response to experimental warming, regardless of seasonal climatic and soil moisture variation. The enzyme results observed here are consistent with the few other experimental results for warming in semiarid ecosystems and indicate that the controls over soil

  7. Plant responses to Agrobacterium tumefaciens and crown gall development

    Science.gov (United States)

    Gohlke, Jochen; Deeken, Rosalia

    2014-01-01

    Agrobacterium tumefaciens causes crown gall disease on various plant species by introducing its T-DNA into the genome. Therefore, Agrobacterium has been extensively studied both as a pathogen and an important biotechnological tool. The infection process involves the transfer of T-DNA and virulence proteins into the plant cell. At that time the gene expression patterns of host plants differ depending on the Agrobacterium strain, plant species and cell-type used. Later on, integration of the T-DNA into the plant host genome, expression of the encoded oncogenes, and increase in phytohormone levels induce a fundamental reprogramming of the transformed cells. This results in their proliferation and finally formation of plant tumors. The process of reprogramming is accompanied by altered gene expression, morphology and metabolism. In addition to changes in the transcriptome and metabolome, further genome-wide (“omic”) approaches have recently deepened our understanding of the genetic and epigenetic basis of crown gall tumor formation. This review summarizes the current knowledge about plant responses in the course of tumor development. Special emphasis is placed on the connection between epigenetic, transcriptomic, metabolomic, and morphological changes in the developing tumor. These changes not only result in abnormally proliferating host cells with a heterotrophic and transport-dependent metabolism, but also cause differentiation and serve as mechanisms to balance pathogen defense and adapt to abiotic stress conditions, thereby allowing the coexistence of the crown gall and host plant. PMID:24795740

  8. Exploring the Response of Plants Grown under Uranium Stress

    Energy Technology Data Exchange (ETDEWEB)

    Doustaly, Fany; Berthet, Serge; Bourguignon, Jacques [CEA, iRTSV, Laboratoire de Physiologie Cellulaire Vegetale, UMR 5168 CEA-CNRS-INRA-Univ. Grenoble Alpes (France); Combes, Florence; Vandenbrouck, Yves [CEA, iRTSV, Laboratoire de Biologie a Grande Echelle, EDyP, CEA-Grenoble (France); Carriere, Marie [CEA, INAC, LAN, UMR E3 CEA-Universite Joseph Fourier, Grenoble (France); Vavasseur, Alain [CEA, IBEB, LBDP, Saint Paul lez Durance, CEA Cadarache (France)

    2014-07-01

    Uranium is a natural element which is mainly redistributed in the environment due to human activity, including accidents and spillages. Plants may be useful in cleaning up after incidents, although little is yet known about the relationship between uranium speciation and plant response. We analyzed the impact of different uranium (U) treatments on three plant species namely sunflower, oilseed rape and wheat. Using inductively coupled plasma mass spectrometry elemental analysis, together with a panel of imaging techniques including scanning electron microscopy coupled with energy dispersive spectroscopy, transmission electron microscopy and particle-induced X-ray emission spectroscopy, we have recently shown how chemical speciation greatly influences the accumulation and distribution of U in plants. Uranyl (UO{sub 2}{sup 2+} free ion) is the predominant mobile form in soil surface at low pH in absence of ligands. With the aim to characterize the early plant response to U exposure, complete Arabidopsis transcriptome microarray experiments were conducted on plants exposed to 50 μM uranyl nitrate for 2, 6 and 30 h and highlighted a set of 111 genes with modified expression at these three time points. Quantitative real-time RT-PCR experiments confirmed and completed CATMA micro-arrays results allowing the characterization of biological processes perturbed by U. Functional categorization of deregulated genes emphasizes oxidative stress, cell wall biosynthesis and hormone biosynthesis and signaling. We showed that U stress is perceived by plant cells like a phosphate starvation stress since several phosphate deprivation marker genes were deregulated by U and also highlighted perturbation of iron homeostasis by U. Hypotheses are presented to explain how U perturbs the iron uptake and signaling response. These results give preliminary insights into the pathways affected by uranyl uptake, which will be of interest for engineering plants to help clean areas contaminated with

  9. Regulation of phosphate starvation responses in higher plants.

    Science.gov (United States)

    Yang, Xiao Juan; Finnegan, Patrick M

    2010-04-01

    Phosphorus (P) is often a limiting mineral nutrient for plant growth. Many soils worldwide are deficient in soluble inorganic phosphate (P(i)), the form of P most readily absorbed and utilized by plants. A network of elaborate developmental and biochemical adaptations has evolved in plants to enhance P(i) acquisition and avoid starvation. Controlling the deployment of adaptations used by plants to avoid P(i) starvation requires a sophisticated sensing and regulatory system that can integrate external and internal information regarding P(i) availability. In this review, the current knowledge of the regulatory mechanisms that control P(i) starvation responses and the local and long-distance signals that may trigger P(i) starvation responses are discussed. Uncharacterized mutants that have P(i)-related phenotypes and their potential to give us additional insights into regulatory pathways and P(i) starvation-induced signalling are also highlighted and assessed. An impressive list of factors that regulate P(i) starvation responses is now available, as is a good deal of knowledge regarding the local and long-distance signals that allow a plant to sense and respond to P(i) availability. However, we are only beginning to understand how these factors and signals are integrated with one another in a regulatory web able to control the range of responses demonstrated by plants grown in low P(i) environments. Much more knowledge is needed in this agronomically important area before real gains can be made in improving P(i) acquisition in crop plants.

  10. Ionic signaling in plant responses to gravity and touch

    Science.gov (United States)

    Fasano, Jeremiah M.; Massa, Gioia D.; Gilroy, Simon

    2002-01-01

    Touch and gravity are two of the many stimuli that plants must integrate to generate an appropriate growth response. Due to the mechanical nature of both of these signals, shared signal transduction elements could well form the basis of the cross-talk between these two sensory systems. However, touch stimulation must elicit signaling events across the plasma membrane whereas gravity sensing is thought to represent transformation of an internal force, amyloplast sedimentation, to signal transduction events. In addition, factors such as turgor pressure and presence of the cell wall may also place unique constraints on these plant mechanosensory systems. Even so, the candidate signal transduction elements in both plant touch and gravity sensing, changes in Ca2+, pH and membrane potential, do mirror the known ionic basis of signaling in animal mechanosensory cells. Distinct spatial and temporal signatures of Ca2+ ions may encode information about the different mechanosignaling stimuli. Signals such as Ca2+ waves or action potentials may also rapidly transfer information perceived in one cell throughout a tissue or organ leading to the systemic reactions characteristic of plant touch and gravity responses. Longer-term growth responses are likely sustained via changes in gene expression and asymmetries in compounds such as inositol-1,4,5-triphosphate (IP3) and calmodulin. Thus, it seems likely that plant mechanoperception involves both spatial and temporal encoding of information at all levels, from the cell to the whole plant. Defining this patterning will be a critical step towards understanding how plants integrate information from multiple mechanical stimuli to an appropriate growth response.

  11. Plant species' origin predicts dominance and response to nutrient enrichment and herbivores in global grasslands

    Science.gov (United States)

    Seabloom, Eric W.; Borer, Elizabeth T.; Buckley, Yvonne M.; Cleland, Elsa E.; Davies, Kendi F.; Firn, Jennifer; Harpole, W. Stanley; Hautier, Yann; Lind, Eric M.; MacDougall, Andrew S.; Orrock, John L.; Prober, Suzanne M.; Adler, Peter B.; Anderson, T. Michael; Bakker, Jonathan D.; Biederman, Lori A.; Blumenthal, Dana M.; Brown, Cynthia S.; Brudvig, Lars A.; Cadotte, Marc; Chu, Chengjin; Cottingham, Kathryn L.; Crawley, Michael J.; Damschen, Ellen I.; Dantonio, Carla M.; DeCrappeo, Nicole M.; Du, Guozhen; Fay, Philip A.; Frater, Paul; Gruner, Daniel S.; Hagenah, Nicole; Hector, Andy; Hillebrand, Helmut; Hofmockel, Kirsten S.; Humphries, Hope C.; Jin, Virginia L.; Kay, Adam; Kirkman, Kevin P.; Klein, Julia A.; Knops, Johannes M. H.; La Pierre, Kimberly J.; Ladwig, Laura; Lambrinos, John G.; Li, Qi; Li, Wei; Marushia, Robin; McCulley, Rebecca L.; Melbourne, Brett A.; Mitchell, Charles E.; Moore, Joslin L.; Morgan, John; Mortensen, Brent; O'Halloran, Lydia R.; Pyke, David A.; Risch, Anita C.; Sankaran, Mahesh; Schuetz, Martin; Simonsen, Anna; Smith, Melinda D.; Stevens, Carly J.; Sullivan, Lauren; Wolkovich, Elizabeth; Wragg, Peter D.; Wright, Justin; Yang, Louie

    2015-01-01

    Exotic species dominate many communities; however the functional significance of species' biogeographic origin remains highly contentious. This debate is fuelled in part by the lack of globally replicated, systematic data assessing the relationship between species provenance, function and response to perturbations. We examined the abundance of native and exotic plant species at 64 grasslands in 13 countries, and at a subset of the sites we experimentally tested native and exotic species responses to two fundamental drivers of invasion, mineral nutrient supplies and vertebrate herbivory. Exotic species are six times more likely to dominate communities than native species. Furthermore, while experimental nutrient addition increases the cover and richness of exotic species, nutrients decrease native diversity and cover. Native and exotic species also differ in their response to vertebrate consumer exclusion. These results suggest that species origin has functional significance, and that eutrophication will lead to increased exotic dominance in grasslands. PMID:26173623

  12. Plant species and soil type cooperatively shape the structure and function of microbial communities in the rhizosphere.

    Science.gov (United States)

    Berg, Gabriele; Smalla, Kornelia

    2009-04-01

    The rhizosphere is of central importance not only for plant nutrition, health and quality but also for microorganism-driven carbon sequestration, ecosystem functioning and nutrient cycling in terrestrial ecosystems. A multitude of biotic and abiotic factors are assumed to influence the structural and functional diversity of microbial communities in the rhizosphere. In this review, recent studies on the influence of the two factors, plant species and soil type, on rhizosphere-associated microbial communities are discussed. Root exudates and the response of microorganisms to the latter as well as to root morphology were shown to shape rhizosphere microbial communities. All studies revealed that soil is the main reservoir for rhizosphere microorganisms. Many secrets of microbial life in the rhizosphere were recently uncovered due to the enormous progress in molecular and microscopic tools. Physiological and molecular data on the factors that drive selection processes in the rhizosphere are presented here. Furthermore, implications for agriculture, nature conservation and biotechnology will also be discussed.

  13. Workforce diversity and community-responsive health-care institutions.

    Science.gov (United States)

    Nivet, Marc A; Berlin, Anne

    2014-01-01

    While the levers for the social determinants of health reside largely outside institutional walls, this does not absolve health professional schools from exercising their influence to improve the communities in which they are located. Fulfilling this charge will require a departure from conventional thinking, particularly when it comes to educating future health professionals. We describe efforts within medical education to transform recruitment, admissions, and classroom environments to emphasize diversity and inclusion. The aim is to cultivate a workforce with the perspectives, aptitudes, and skills needed to fuel community-responsive health-care institutions.

  14. Plant-phytopathogen interactions: bacterial responses to environmental and plant stimuli.

    Science.gov (United States)

    Leonard, Simon; Hommais, Florence; Nasser, William; Reverchon, Sylvie

    2017-05-01

    Plant pathogenic bacteria attack numerous agricultural crops, causing devastating effects on plant productivity and yield. They survive in diverse environments, both in plants, as pathogens, and also outside their hosts as saprophytes. Hence, they are confronted with numerous changing environmental parameters. During infection, plant pathogens have to deal with stressful conditions, such as acidic, oxidative and osmotic stresses; anaerobiosis; plant defenses; and contact with antimicrobial compounds. These adverse conditions can reduce bacterial survival and compromise disease initiation and propagation. Successful bacterial plant pathogens must detect potential hosts and also coordinate their possibly conflicting programs for survival and virulence. Consequently, these bacteria have a strong and finely tuned capacity for sensing and responding to environmental and plant stimuli. This review summarizes our current knowledge of the signals and genetic circuits that affect survival and virulence factor expression in three important and well-studied plant pathogenic bacteria with wide host ranges and the capacity for long-term environmental survival. These are: Ralstonia solanacerarum, a vascular pathogen that causes wilt disease; Agrobacterium tumefaciens, a biotrophic tumorigenic pathogen responsible for crown gall disease and Dickeya, a brute force apoplastic pathogen responsible for soft-rot disease. © 2016 Society for Applied Microbiology and John Wiley & Sons Ltd.

  15. Plant surface wax affects parasitoid's response to host footprints

    Science.gov (United States)

    Rostás, Michael; Ruf, Daniel; Zabka, Vanessa; Hildebrandt, Ulrich

    2008-10-01

    The plant surface is the substrate upon which herbivorous insects and natural enemies meet and thus represents the stage for interactions between the three trophic levels. Plant surfaces are covered by an epicuticular wax layer which is highly variable depending on species, cultivar or plant part. Differences in wax chemistry may modulate ecological interactions. We explored whether caterpillars of Spodoptera frugiperda, when walking over a plant surface, leave a chemical trail (kairomones) that can be detected by the parasitoid Cotesia marginiventris. Chemistry and micromorphology of cuticular waxes of two barley eceriferum wax mutants ( cer-za.126, cer-yp.949) and wild-type cv. Bonus (wt) were assessed. The plants were then used to investigate potential surface effects on the detectability of caterpillar kairomones. Here we provide evidence that C. marginiventris responds to chemical footprints of its host. Parasitoids were able to detect the kairomone on wild-type plants and on both cer mutants but the response to cer-yp.949 (reduced wax, high aldehyde fraction) was less pronounced. Experiments with caterpillar-treated wt and mutant leaves offered simultaneously, confirmed this observation: no difference in wasp response was found when wt was tested against cer-za.126 (reduced wax, wt-like chemical composition) but wt was significantly more attractive than cer-yp.949. This demonstrates for the first time that the wax layer can modulate the detectability of host kairomones.

  16. Glutathione-dependent responses of plants to drought: a review

    Directory of Open Access Journals (Sweden)

    Mateusz Labudda

    2014-02-01

    Full Text Available Water is a renewable resource. However, with the human population growth, economic development and improved living standards, the world’s supply of fresh water is steadily decreasing and consequently water resources for agricultural production are limited and diminishing. Water deficiency is a significant problem in agriculture and increasing efforts are currently being made to understand plant tolerance mechanisms and to develop new tools (especially molecular that could underpin plant breeding and cultivation. However, the biochemical and molecular mechanisms of plant water deficit tolerance are not fully understood, and the data available is incomplete. Here, we review the significance of glutathione and its related enzymes in plant responses to drought. Firstly, the roles of reduced glutathione and reduced/oxidized glutathione ratio, are discussed, followed by an extensive discussion of glutathione related enzymes, which play an important role in plant responses to drought. Special attention is given to the S-glutathionylation of proteins, which is involved in cell metabolism regulation and redox signaling in photosynthetic organisms subjected to abiotic stress. The review concludes with a brief overview of future perspectives for the involvement of glutathione and related enzymes in drought stress responses.

  17. Gender-related traits in the dioecious shrub Empetrum rubrum in two plant communities in the Magellanic steppe

    Science.gov (United States)

    Díaz-Barradas, Mari Cruz; Zunzunegui, María; Collantes, Marta; Álvarez-Cansino, Leonor; García Novo, Francisco

    2014-10-01

    Following the theory on costs of reproduction, sexually dimorphic plants may exhibit several trade-offs in energy and resources that can determine gender dimorphism in morphological or physiological traits, especially during the reproductive period. In this study we assess whether the sexes of the dioecious species Empetrum rubrum differ in morphological and ecophysiological traits related to water economy and photochemical efficiency and whether these differences change in nearby populations with contrasting plant communities. We conducted physiological, morphological, sex ratio, and cover measurements in E. rubrum plants in the Magellanic steppe, North-Eastern part of Tierra del Fuego (Argentina), from two types of heathlands with differing community composition. We found differences between sites in soil pH and wind speed at the canopy level. E. rubrum plants exhibited lower photosynthetic height and higher LAI (leaf area index), lower RWC (relative water content) and higher water-use efficiency (lower Δ13C) in the heathland with harsher environmental conditions. Gender dimorphism in the physiological response was patent for photochemical efficiency and water use (RWC and Δ13C discrimination), with males showing a more conservative strategy in relation to females. Accordingly, male-biased sex ratio in the stress-prone community suggested a better performance of male plants under stressful environmental conditions. The integrated analysis of all variables (photochemical efficiency, RWC, leaf dry matter content (LDMC), pigments, and Δ13C) indicated an interaction between gender and heathland community effects in the physiological response. We suggest that female plants may exhibit compensatory mechanisms to face their higher reproductive costs.

  18. An Overview of the Genetics of Plant Response to Salt Stress: Present Status and the Way Forward.

    Science.gov (United States)

    Kaleem, Fawad; Shabir, Ghulam; Aslam, Kashif; Rasul, Sumaira; Manzoor, Hamid; Shah, Shahid Masood; Khan, Abdul Rehman

    2018-04-02

    Salinity is one of the major threats faced by the modern agriculture today. It causes multidimensional effects on plants. These effects depend upon the plant growth stage, intensity, and duration of the stress. All these lead to stunted growth and reduced yield, ultimately inducing economic loss to the farming community in particular and to the country in general. The soil conditions of agricultural land are deteriorating at an alarming rate. Plants assess the stress conditions, transmit the specific stress signals, and then initiate the response against that stress. A more complete understanding of plant response mechanisms and their practical incorporation in crop improvement is an essential step towards achieving the goal of sustainable agricultural development. Literature survey shows that investigations of plant stresses response mechanism are the focus area of research for plant scientists. Although these efforts lead to reveal different plant response mechanisms against salt stress, yet many questions still need to be answered to get a clear picture of plant strategy to cope with salt stress. Moreover, these studies have indicated the presence of a complicated network of different integrated pathways. In order to work in a progressive way, a review of current knowledge is critical. Therefore, this review aims to provide an overview of our understanding of plant response to salt stress and to indicate some important yet unexplored dynamics to improve our knowledge that could ultimately lead towards crop improvement.

  19. Litter Accumulation and Nutrient Content of Roadside Plant Communities in Sichuan Basin, China

    OpenAIRE

    He, Huiqin; Monaco, Thomas

    2017-01-01

    It is widely recognized that feedbacks exist between plant litter and plant community species composition, but this relationship is difficult to interpret over heterogeneous conditions typical of modified environments such as roadways. Given the need to expedite natural recovery of disturbed areas through restoration interventions, we characterized litter accumulation and nutrient content (i.e., organic carbon, total N, and P) and quantified their association with key plant species. Plant spe...

  20. Allelopathy and resource competition: the effects of Phragmites australis invasion in plant communities

    OpenAIRE

    Uddin, Md Nazim; Robinson, Randall William

    2017-01-01

    Background Phragmites australis, a ubiquitous wetland plant, has been considered one of the most invasive species in the world. Allelopathy appears to be one of the invasion mechanisms, however, the effects could be masked by resource competition among target plants. The difficulty of distinguishing allelopathy from resource competition among plants has hindered investigations of the role of phytotoxic allelochemicals in plant communities. This has been addressed via experiments conducted in ...

  1. Jasmonate-responsive transcription factors regulating plant secondary metabolism.

    Science.gov (United States)

    Zhou, Meiliang; Memelink, Johan

    2016-01-01

    Plants produce a large variety of secondary metabolites including alkaloids, glucosinolates, terpenoids and phenylpropanoids. These compounds play key roles in plant-environment interactions and many of them have pharmacological activity in humans. Jasmonates (JAs) are plant hormones which induce biosynthesis of many secondary metabolites. JAs-responsive transcription factors (TFs) that regulate the JAs-induced accumulation of secondary metabolites belong to different families including AP2/ERF, bHLH, MYB and WRKY. Here, we give an overview of the types and functions of TFs that have been identified in JAs-induced secondary metabolite biosynthesis, and highlight their similarities and differences in regulating various biosynthetic pathways. We review major recent developments regarding JAs-responsive TFs mediating secondary metabolite biosynthesis, and provide suggestions for further studies. Copyright © 2016 Elsevier Inc. All rights reserved.

  2. Grape marc extract acts as elicitor of plant defence responses.

    Science.gov (United States)

    Goupil, Pascale; Benouaret, Razik; Charrier, Olivia; Ter Halle, Alexandra; Richard, Claire; Eyheraguibel, Boris; Thiery, Denis; Ledoigt, Gérard

    2012-07-01

    Plant protection based on novel alternative strategies is a major concern in agriculture to sustain pest management. The marc extract of red grape cultivars reveals plant defence inducer properties. Treatment with grape marc extract efficiently induced hypersensitive reaction-like lesions with cell death evidenced by Evans Blue staining of tobacco leaves. Examination of the infiltration zone and the surrounding areas under UV light revealed the accumulation of autofluorescent compounds. Both leaf infiltration and a foliar spray of the red grape extract on tobacco leaves induced defence gene expression. The PR1 and PR2 target genes were upregulated locally and systemically in tobacco plants following grape marc extract treatment. The grape extract elicited an array of plant defence responses making this natural compound a potential phytosanitary product with a challenging issue and a rather attractive option for sustainable agriculture and environmentally friendly practices.

  3. Introducing cattle grazing to a noxious weed-dominated rangeland shifts plant communities

    Directory of Open Access Journals (Sweden)

    Josh S. Davy

    2015-10-01

    Full Text Available Invasive weed species in California's rangelands can reduce herbaceous diversity, forage quality and wildlife habitat. Small-scale studies (5 acres or fewer have shown reductions of medusahead and yellow starthistle using prescribed grazing on rangelands, but little is published on the effects of pasture-scale (greater than 80 acres prescribed grazing on weed control and plant community responses. We report the results of a 6-year collaborative study of manager-applied prescribed grazing implemented on rangeland that had not been grazed for 4 years. Grazing reduced medusahead but did not alter yellow starthistle cover. Medusahead reductions were only seen in years that did not have significant late spring rainfall, suggesting that it is able to recover from heavy grazing if soil moisture is present. Later season grazing appears to have the potential to suppress medusahead in all years. In practice, however, such grazing is constrained by livestock drinking water availability and forage quality, which were limited even in years with late spring rainfall. Thus, we expect that grazing treatments under real-world constraints would reduce medusahead only in years with little late spring rainfall. After 10 years of grazing exclusion, the ungrazed plant communities began to shift, replacing medusahead with species that have little value, such as ripgut and red brome.

  4. Field Guide to the Plant Community Types of Voyageurs National Park

    Science.gov (United States)

    Faber-Langendoen, Don; Aaseng, Norman; Hop, Kevin; Lew-Smith, Michael

    2007-01-01

    INTRODUCTION The objective of the U.S. Geological Survey-National Park Service Vegetation Mapping Program is to classify, describe, and map vegetation for most of the park units within the National Park Service (NPS). The program was created in response to the NPS Natural Resources Inventory and Monitoring Guidelines issued in 1992. Products for each park include digital files of the vegetation map and field data, keys and descriptions to the plant communities, reports, metadata, map accuracy verification summaries, and aerial photographs. Interagency teams work in each park and, following standardized mapping and field sampling protocols, develop products and vegetation classification standards that document the various vegetation types found in a given park. The use of a standard national vegetation classification system and mapping protocol facilitate effective resource stewardship by ensuring compatibility and widespread use of the information throughout the NPS as well as by other Federal and state agencies. These vegetation classifications and maps and associated information support a wide variety of resource assessment, park management, and planning needs, and provide a structure for framing and answering critical scientific questions about plant communities and their relation to environmental processes across the landscape. This field guide is intended to make the classification accessible to park visitors and researchers at Voyageurs National Park, allowing them to identify any stand of natural vegetation and showing how the classification can be used in conjunction with the vegetation map (Hop and others, 2001).

  5. Physiological blockage in plants in response to postharvest stress

    African Journals Online (AJOL)

    Marcos

    2013-03-13

    Mar 13, 2013 ... response of the plant to cut stem (Ichimura et al., 1999). When the vessel is blocked, ... E-mail: m.r.s.v@hotmail.com. of complex physiological ... of cells which protrude into the vessel lumen xylem whose shape is similar to a.

  6. Physiological blockage in plants in response to postharvest stress

    African Journals Online (AJOL)

    Marcos

    2013-03-13

    Mar 13, 2013 ... response of the plant to cut stem (Ichimura et al., 1999). When the vessel is ... blockage due to microbial growth and blockage caused by formation of .... HQS) and chlorine, are used to assess its actions in the microorganisms ...

  7. Responses of soilless grown tomato plants to arbuscular ...

    African Journals Online (AJOL)

    STORAGESEVER

    2008-10-20

    Oct 20, 2008 ... Full Length Research Paper. Responses of soilless grown tomato plants to arbuscular mycorrhizal fungal (Glomus fasciculatum) colonization in re-cycling and open systems. H. Yildiz Dasgan1*, Sebnem Kusvuran1 and Ibrahim Ortas2. 1Cukurova University, Faculty of Agriculture, Department of Horticulture ...

  8. Bottom-up and top-down effects on plant communities

    DEFF Research Database (Denmark)

    Souza, Lara; Zelikova, Tamara Jane; Sanders, Nate

    2016-01-01

    -down) and soil nitrogen (bottom-up) were manipulated over six years in an existing old-field community. We tracked plant α and β diversity - within plot richness and among plot biodiversity- and aboveground net primary productivity (ANPP) over the course of the experiment. We found that bottom-up factors...... affected ANPP while top-down factors influenced plant community structure. Across years, while N reduction lowered ANPP by 10%, N reduction did not alter ANPP relative to control plots. Further, N reduction lowered ANPP by 20% relative to N addition plots. On the other hand, the reduction of insect...... community composition via shifts in plant dominance....

  9. Holocene Substrate Influences on Plant and Fire Response to Climate Change

    Science.gov (United States)

    Briles, C.; Whitlock, C. L.

    2011-12-01

    The role of substrates in facilitating plant responses to climate change in the past has received little attention. Ecological studies, documenting the relative role of fertile and infertile substrates in mediating the effects of climate change, lack the temporal information that paleoecological lake studies provide on how plants have responded under equal, larger and more rapid past climate events than today. In this paper, pollen and macroscopic charcoal preserved in the sediments of eight lakes surrounded by infertile ultramafic soils and more fertile soils in the Klamath Mountains of northern California were analyzed. Comparison of late-Quaternary paleoecological sites suggests that infertile and fertile substrates supported distinctly different plant communities. Trees and shrubs on infertile substrates were less responsive to climate change than those on fertile substrates, with the only major compositional change occurring at the glacial/interglacial transition (~11.5ka), when temperature rose 5oC. Trees and shrubs on fertile substrates were more responsive to climate changes, and tracked climate by moving along elevational gradients, including during more recent climate events such as the Little Ice Age and Medieval Climate Anomaly. Fire regimes were similar until 4ka on both substrate types. After 4ka, understory fuels on infertile substrates became sparse and fire activity decreased, while on fertile substrates forests became increasingly denser and fire activity increased. The complacency of plant communities on infertile sites to climate change contrasts with the individualistic and rapid adjustments of species on fertile sites. The findings differ from observations on shorter time scales that show the most change in herb cover and richness in the last 60 years on infertile substrates. Thus, the paleorecord provides unique long-term ecological data necessary to evaluate the response of plants to future climate change under different levels of soil

  10. Evolutionary history and novel biotic interactions determine plant responses to elevated CO2 and nitrogen fertilization.

    Directory of Open Access Journals (Sweden)

    Rachel Wooliver

    Full Text Available A major frontier in global change research is predicting how multiple agents of global change will alter plant productivity, a critical component of the carbon cycle. Recent research has shown that plant responses to climate change are phylogenetically conserved such that species within some lineages are more productive than those within other lineages in changing environments. However, it remains unclear how phylogenetic patterns in plant responses to changing abiotic conditions may be altered by another agent of global change, the introduction of non-native species. Using a system of 28 native Tasmanian Eucalyptus species belonging to two subgenera, Symphyomyrtus and Eucalyptus, we hypothesized that productivity responses to abiotic agents of global change (elevated CO2 and increased soil N are unique to lineages, but that novel interactions with a non-native species mediate these responses. We tested this hypothesis by examining productivity of 1 native species monocultures and 2 mixtures of native species with an introduced hardwood plantation species, Eucalyptus nitens, to experimentally manipulated soil N and atmospheric CO2. Consistent with past research, we found that N limits productivity overall, especially in elevated CO2 conditions. However, monocultures of species within the Symphyomyrtus subgenus showed the strongest response to N (gained 127% more total biomass in elevated CO2 conditions, whereas those within the Eucalyptus subgenus did not respond to N. Root:shoot ratio (an indicator of resource use was on average greater in species pairs containing Symphyomyrtus species, suggesting that functional traits important for resource uptake are phylogenetically conserved and explaining the phylogenetic pattern in plant response to changing environmental conditions. Yet, native species mixtures with E. nitens exhibited responses to CO2 and N that differed from those of monocultures, supporting our hypothesis and highlighting that both

  11. Warming increases plant biomass and reduces diversity across continents, latitudes, and species migration scenarios in experimental wetland communities.

    Science.gov (United States)

    Baldwin, Andrew H; Jensen, Kai; Schönfeldt, Marisa

    2014-03-01

    Atmospheric warming may influence plant productivity and diversity and induce poleward migration of species, altering communities across latitudes. Complicating the picture is that communities from different continents deviate in evolutionary histories, which may modify responses to warming and migration. We used experimental wetland plant communities grown from seed banks as model systems to determine whether effects of warming on biomass production and species richness are consistent across continents, latitudes, and migration scenarios. We collected soil samples from each of three tidal freshwater marshes in estuaries at three latitudes (north, middle, south) on the Atlantic coasts of Europe and North America. In one experiment, we exposed soil seed bank communities from each latitude and continent to ambient and elevated (+2.8 °C) temperatures in the greenhouse. In a second experiment, soil samples were mixed either within each estuary (limited migration) or among estuaries from different latitudes in each continent (complete migration). Seed bank communities of these migration scenarios were also exposed to ambient and elevated temperatures and contrasted with a no-migration treatment. In the first experiment, warming overall increased biomass (+16%) and decreased species richness (-14%) across latitudes in Europe and North America. Species richness and evenness of south-latitude communities were less affected by warming than those of middle and north latitudes. In the second experiment, warming also stimulated biomass and lowered species richness. In addition, complete migration led to increased species richness (+60% in North America, + 100% in Europe), but this higher diversity did not translate into increased biomass. Species responded idiosyncratically to warming, but Lythrum salicaria and Bidens sp. increased significantly in response to warming in both continents. These results reveal for the first time consistent impacts of warming on biomass and

  12. Soil microbial community structure is unaltered by plant invasion, vegetation clipping, and nitrogen fertilization in experimental semi-arid grasslands

    Directory of Open Access Journals (Sweden)

    Chelsea J Carey

    2015-05-01

    Full Text Available Global and regional environmental changes often co-occur, creating complex gradients of disturbance on the landscape. Soil microbial communities are an important component of ecosystem response to environmental change, yet little is known about how microbial structure and function respond to multiple disturbances, or whether multiple environmental changes lead to unanticipated interactive effects. Our study used experimental semi-arid grassland plots in a Mediterranean-climate to determine how soil microbial communities in a seasonally variable ecosystem respond to one, two, or three simultaneous environmental changes: exotic plant invasion, plant invasion + vegetation clipping (to simulate common management practices like mowing or livestock grazing, plant invasion + nitrogen (N fertilization, and plant invasion + clipping + N fertilization. We examined microbial community structure 5-6 years after plot establishment via sequencing of >1 million 16S rRNA genes. Abiotic soil properties (soil moisture, temperature, pH, and inorganic N and microbial functioning (nitrification and denitrification potentials were also measured and showed treatment-induced shifts, including altered NO3- availability, temperature, and nitrification potential. Despite these changes, bacterial and archaeal communities showed little variation in composition and diversity across treatments. Even communities in plots exposed to three interacting environmental changes were similar to those in restored native grassland plots. Historical exposure to large seasonal and inter-annual variations in key soil properties, in addition to prior site cultivation, may select for a functionally plastic or largely dormant microbial community, resulting in a microbial community that is structurally robust to single and multiple environmental changes.

  13. Responses to invasion and invader removal differ between native and exotic plant groups in a coastal dune.

    Science.gov (United States)

    Magnoli, Susan M; Kleinhesselink, Andrew R; Cushman, J Hall

    2013-12-01

    The spread of exotic, invasive species is a global phenomenon that is recognized as a major source of environmental change. Although many studies have addressed the effects of exotic plants on the communities they invade, few have quantified the effects of invader removal on plant communities, or considered the degree to which different plant groups vary in response to invasion and invader removal. We evaluated the effects of an exotic succulent, iceplant (Carpobrotus edulis), on a coastal dune plant community in northern California, as well as the community responses to its removal. To assess possible mechanisms by which iceplant affects other plants, we also evaluated its above- and belowground influences on the germination and growth of a dominant exotic annual grass, Bromus diandrus. We found that iceplant invasion was associated with reduced native plant cover as well as increased cover and density of some exotic plants-especially exotic annual grasses. However, iceplant removal did not necessarily lead to a reversal of these effects: removal increased the cover and density of both native and exotic species. We also found that B. diandrus grown in iceplant patches, or in soil where iceplant had been removed, had poorer germination and growth than B. diandrus grown in soil not influenced by iceplant. This suggests that the influence of iceplant on this dune plant community occurs, at least in part, due to belowground effects, and that these effects remain after iceplant has been removed. Our study demonstrates the importance of considering how exotic invasive plants affect not only native species, but also co-occurring exotic taxa. It also shows that combining observational studies with removal experiments can lead to important insights into the influence of invaders and the mechanisms of their effects.

  14. Relative Importance and Knowledge Distribution of Medicinal Plants in a Kichwa Community in the Ecuadorian Amazon

    Directory of Open Access Journals (Sweden)

    Brian Joseph Doyle

    2017-01-01

    Full Text Available Traditional knowledge, such as knowledge of the use of plants as medicine, influences how indigenous people manage forest resources. Gender and age-associated differences in traditional knowledge may impact forest resource management because of the traditional division of labor. We interviewed 18 men and 18 women between 9 and 74 years old in San José de Payamino, an indigenous community of the Kichwa ethnicity in the Ecuadorian Amazon, to determine if there are gender or age-associated differences in medicinal plant knowledge among the Payamino people and to identify the most important species from a sample of medicinal plants. Individuals were interviewed using a tablet that displayed images of 34 plants, which had been cited by traditional healers in the community. Quantitative analysis provided insight into the relative importance of plants in the sample as well as the distribution of medicinal plant knowledge among members of the community. The most important plants were Tradescantia zanonia and Monolena primuliflora. These plants should be considered candidates for further investigation. There was a positive correlation between age and knowledge of medicinal plants, but no significant difference between genders. Our results suggest that an interview method that relies on digital images can reveal differences in the importance of medicinal plants as well as provide insight into the distribution of traditional medical knowledge. While men and women are likely to manage forest resources similarly, younger members of the community may not have the same regard for forest resources as their elder counterparts.

  15. Petroleum Contamination and Plant Identity Influence Soil and Root Microbial Communities While AMF Spores Retrieved from the Same Plants Possess Markedly Different Communities.

    Science.gov (United States)

    Iffis, Bachir; St-Arnaud, Marc; Hijri, Mohamed

    2017-01-01

    Phytoremediation is a promising in situ green technology based on the use of plants to cleanup soils from organic and inorganic pollutants. Microbes, particularly bacteria and fungi, that closely interact with plant roots play key roles in phytoremediation processes. In polluted soils, the root-associated microbes contribute to alleviation of plant stress, improve nutrient uptake and may either degrade or sequester a large range of soil pollutants. Therefore, improving the efficiency of phytoremediation requires a thorough knowledge of the microbial diversity living in the rhizosphere and in close association with plant roots in both the surface and the endosphere. This study aims to assess fungal ITS and bacterial 16S rRNA gene diversity using high-throughput sequencing in rhizospheric soils and roots of three plant species ( Solidago canadensis, Populus balsamifera , and Lycopus europaeus ) growing spontaneously in three petroleum hydrocarbon polluted sedimentation basins. Microbial community structures of rhizospheric soils and roots were compared with those of microbes associated with arbuscular mycorrhizal fungal (AMF) spores to determine the links between the root and rhizosphere communities and those associated with AMF. Our results showed a difference in OTU richness and community structure composition between soils and roots for both bacteria and fungi. We found that petroleum hydrocarbon pollutant (PHP) concentrations have a significant effect on fungal and bacterial community structures in both soils and roots, whereas plant species identity showed a significant effect only on the roots for bacteria and fungi. Our results also showed that the community composition of bacteria and fungi in soil and roots varied from those associated with AMF spores harvested from the same plants. This let us to speculate that in petroleum hydrocarbon contaminated soils, AMF may release chemical compounds by which they recruit beneficial microbes to tolerate or degrade the

  16. Petroleum Contamination and Plant Identity Influence Soil and Root Microbial Communities While AMF Spores Retrieved from the Same Plants Possess Markedly Different Communities

    Directory of Open Access Journals (Sweden)

    Bachir Iffis

    2017-08-01

    Full Text Available Phytoremediation is a promising in situ green technology based on the use of plants to cleanup soils from organic and inorganic pollutants. Microbes, particularly bacteria and fungi, that closely interact with plant roots play key roles in phytoremediation processes. In polluted soils, the root-associated microbes contribute to alleviation of plant stress, improve nutrient uptake and may either degrade or sequester a large range of soil pollutants. Therefore, improving the efficiency of phytoremediation requires a thorough knowledge of the microbial diversity living in the rhizosphere and in close association with plant roots in both the surface and the endosphere. This study aims to assess fungal ITS and bacterial 16S rRNA gene diversity using high-throughput sequencing in rhizospheric soils and roots of three plant species (Solidago canadensis, Populus balsamifera, and Lycopus europaeus growing spontaneously in three petroleum hydrocarbon polluted sedimentation basins. Microbial community structures of rhizospheric soils and roots were compared with those of microbes associated with arbuscular mycorrhizal fungal (AMF spores to determine the links between the root and rhizosphere communities and those associated with AMF. Our results showed a difference in OTU richness and community structure composition between soils and roots for both bacteria and fungi. We found that petroleum hydrocarbon pollutant (PHP concentrations have a significant effect on fungal and bacterial community structures in both soils and roots, whereas plant species identity showed a significant effect only on the roots for bacteria and fungi. Our results also showed that the community composition of bacteria and fungi in soil and roots varied from those associated with AMF spores harvested from the same plants. This let us to speculate that in petroleum hydrocarbon contaminated soils, AMF may release chemical compounds by which they recruit beneficial microbes to tolerate

  17. Petroleum Contamination and Plant Identity Influence Soil and Root Microbial Communities While AMF Spores Retrieved from the Same Plants Possess Markedly Different Communities

    Science.gov (United States)

    Iffis, Bachir; St-Arnaud, Marc; Hijri, Mohamed

    2017-01-01

    Phytoremediation is a promising in situ green technology based on the use of plants to cleanup soils from organic and inorganic pollutants. Microbes, particularly bacteria and fungi, that closely interact with plant roots play key roles in phytoremediation processes. In polluted soils, the root-associated microbes contribute to alleviation of plant stress, improve nutrient uptake and may either degrade or sequester a large range of soil pollutants. Therefore, improving the efficiency of phytoremediation requires a thorough knowledge of the microbial diversity living in the rhizosphere and in close association with plant roots in both the surface and the endosphere. This study aims to assess fungal ITS and bacterial 16S rRNA gene diversity using high-throughput sequencing in rhizospheric soils and roots of three plant species (Solidago canadensis, Populus balsamifera, and Lycopus europaeus) growing spontaneously in three petroleum hydrocarbon polluted sedimentation basins. Microbial community structures of rhizospheric soils and roots were compared with those of microbes associated with arbuscular mycorrhizal fungal (AMF) spores to determine the links between the root and rhizosphere communities and those associated with AMF. Our results showed a difference in OTU richness and community structure composition between soils and roots for both bacteria and fungi. We found that petroleum hydrocarbon pollutant (PHP) concentrations have a significant effect on fungal and bacterial community structures in both soils and roots, whereas plant species identity showed a significant effect only on the roots for bacteria and fungi. Our results also showed that the community composition of bacteria and fungi in soil and roots varied from those associated with AMF spores harvested from the same plants. This let us to speculate that in petroleum hydrocarbon contaminated soils, AMF may release chemical compounds by which they recruit beneficial microbes to tolerate or degrade the

  18. The Effects of Timing of Grazing on Plant and Arthropod Communities in High-Elevation Grasslands

    Science.gov (United States)

    Davis, Stacy C.; Burkle, Laura A.; Cross, Wyatt F.; Cutting, Kyle A.

    2014-01-01

    Livestock grazing can be used as a key management tool for maintaining healthy ecosystems. However, the effectiveness of using grazing to modify habitat for species of conservation concern depends on how the grazing regime is implemented. Timing of grazing is one grazing regime component that is less understood than grazing intensity and grazer identity, but is predicted to have important implications for plant and higher trophic level responses. We experimentally assessed how timing of cattle grazing affected plant and arthropod communities in high-elevation grasslands of southwest Montana to better evaluate its use as a tool for multi-trophic level management. We manipulated timing of grazing, with one grazing treatment beginning in mid-June and the other in mid-July, in two experiments conducted in different grassland habitat types (i.e., wet meadow and upland) in 2011 and 2012. In the upland grassland experiment, we found that both early and late grazing treatments reduced forb biomass, whereas graminoid biomass was only reduced with late grazing. Grazing earlier in the growing season versus later did not result in greater recovery of graminoid or forb biomass as expected. In addition, the density of the most ubiquitous grassland arthropod order (Hemiptera) was reduced by both grazing treatments in upland grasslands. A comparison of end-of-season plant responses to grazing in upland versus wet meadow grasslands revealed that grazing reduced graminoid biomass in the wet meadow and forb biomass in the upland, irrespective of timing of grazing. Both grazing treatments also reduced end-of-season total arthropod and Hemiptera densities and Hemiptera biomass in both grassland habitat types. Our results indicate that both early and late season herbivory affect many plant and arthropod characteristics in a similar manner, but grazing earlier may negatively impact species of conservation concern requiring forage earlier in the growing season. PMID:25338008

  19. Interspecific Plant Interactions Reflected in Soil Bacterial Community Structure and Nitrogen Cycling in Primary Succession

    Directory of Open Access Journals (Sweden)

    Joseph E. Knelman

    2018-02-01

    Full Text Available Past research demonstrating the importance plant–microbe interactions as drivers of ecosystem succession has focused on how plants condition soil microbial communities, impacting subsequent plant performance and plant community assembly. These studies, however, largely treat microbial communities as a black box. In this study, we sought to examine how emblematic shifts from early successional Alnus viridus ssp. sinuata (Sitka alder to late successional Picea sitchensis (Sitka spruce in primary succession may be reflected in specific belowground changes in bacterial community structure and nitrogen cycling related to the interaction of these two plants. We examined early successional alder-conditioned soils in a glacial forefield to delineate how alders alter the soil microbial community with increasing dominance. Further, we assessed the impact of late-successional spruce plants on these early successional alder-conditioned microbiomes and related nitrogen cycling through a leachate addition microcosm experiment. We show how increasingly abundant alder select for particular bacterial taxa. Additionally, we found that spruce leachate significantly alters the composition of these microbial communities in large part by driving declines in taxa that are enriched by alder, including bacterial symbionts. We found these effects to be spruce specific, beyond a general leachate effect. Our work also demonstrates a unique influence of spruce on ammonium availability. Such insights bolster theory relating the importance of plant–microbe interactions with late-successional plants and interspecific plant interactions more generally.

  20. Green thermoelectrics: Observation and analysis of plant thermoelectric response

    Directory of Open Access Journals (Sweden)

    Goupil Christophe

    2016-01-01

    Full Text Available Plants are sensitive to thermal and electrical effects; yet the coupling of both, known as thermoelectricity, and its quantitative measurement in vegetal systems never were reported. We recorded the thermoelectric response of bean sprouts under various thermal conditions and stress. The obtained experimental data unambiguously demonstrate that a temperature difference between the roots and the leaves of a bean sprout induces a thermoelectric voltage between these two points. Basing our analysis of the data on the force-flux formalism of linear response theory, we found that the strength of the vegetal equivalent to the thermoelectric coupling is one order of magnitude larger than that in the best thermoelectric materials. Experimental data also show the importance of the thermal stress variation rate in the plant’s electrophysiological response. therefore, thermoelectric effects are sufficiently important to partake in the complex and intertwined processes of energy and matter transport within plants.

  1. Unraveling plant responses to bacterial pathogens through proteomics

    KAUST Repository

    Zimaro, Tamara

    2011-11-03

    Plant pathogenic bacteria cause diseases in important crops and seriously and negatively impact agricultural production. Therefore, an understanding of the mechanisms by which plants resist bacterial infection at the stage of the basal immune response or mount a successful specific R-dependent defense response is crucial since a better understanding of the biochemical and cellular mechanisms underlying these interactions will enable molecular and transgenic approaches to crops with increased biotic resistance. In recent years, proteomics has been used to gain in-depth understanding of many aspects of the host defense against pathogens and has allowed monitoring differences in abundance of proteins as well as posttranscriptional and posttranslational processes, protein activation/inactivation, and turnover. Proteomics also offers a window to study protein trafficking and routes of communication between organelles. Here, we summarize and discuss current progress in proteomics of the basal and specific host defense responses elicited by bacterial pathogens. Copyright 2011 Tamara Zimaro et al.

  2. Unraveling plant responses to bacterial pathogens through proteomics

    KAUST Repository

    Zimaro, Tamara; Gottig, Natalia; Garavaglia, Betiana S.; Gehring, Christoph A; Ottado, Jorgelina

    2011-01-01

    Plant pathogenic bacteria cause diseases in important crops and seriously and negatively impact agricultural production. Therefore, an understanding of the mechanisms by which plants resist bacterial infection at the stage of the basal immune response or mount a successful specific R-dependent defense response is crucial since a better understanding of the biochemical and cellular mechanisms underlying these interactions will enable molecular and transgenic approaches to crops with increased biotic resistance. In recent years, proteomics has been used to gain in-depth understanding of many aspects of the host defense against pathogens and has allowed monitoring differences in abundance of proteins as well as posttranscriptional and posttranslational processes, protein activation/inactivation, and turnover. Proteomics also offers a window to study protein trafficking and routes of communication between organelles. Here, we summarize and discuss current progress in proteomics of the basal and specific host defense responses elicited by bacterial pathogens. Copyright 2011 Tamara Zimaro et al.

  3. Impacts of atmospheric pollution on the plant communities of British acid grasslands

    Energy Technology Data Exchange (ETDEWEB)

    Payne, Richard J., E-mail: r.payne@mmu.ac.uk [School of Science and the Environment, Manchester Metropolitan University, Chester St., Manchester M1 5GD (United Kingdom); Geography, School of Environment and Development, University of Manchester, Oxford Road, Manchester M13 9PL (United Kingdom); Stevens, Carly J. [Faculty of Science, Open University, Walton Hall, Milton Keynes MK7 6AA (United Kingdom); Lancaster Environment Centre, Lancaster University, Bailrigg, Lancaster LA1 4YQ (United Kingdom); Dise, Nancy B. [School of Science and the Environment, Manchester Metropolitan University, Chester St., Manchester M1 5GD (United Kingdom); Gowing, David J. [Faculty of Science, Open University, Walton Hall, Milton Keynes MK7 6AA (United Kingdom); Pilkington, Michael G.; Phoenix, Gareth K. [Department of Animal and Plant Sciences, Alfred Denny Building, University of Sheffield, Sheffield S10 2TN (United Kingdom); Emmett, Bridget A. [Centre for Ecology and Hydrology, Environment Centre Wales, Deiniol Road, Bangor, Gwynedd LL57 2UW (United Kingdom); Ashmore, Michael R. [Environment Department, University of York, Heslington, York YO10 5DD (United Kingdom)

    2011-10-15

    Air pollutants are recognised as important agents of ecosystem change but few studies consider the effects of multiple pollutants and their interactions. Here we use ordination, constrained cluster analysis and indicator value analyses to identify potential environmental controls on species composition, ecological groupings and indicator species in a gradient study of UK acid grasslands. The community composition of these grasslands is related to climate, grazing, ozone exposure and nitrogen deposition, with evidence for an interaction between the ecological impacts of base cation and nitrogen deposition. Ozone is a key agent in species compositional change but is not associated with a reduction in species richness or diversity indices, showing the subtly different drivers on these two aspects of ecosystem degradation. Our results demonstrate the effects of multiple interacting pollutants, which may collectively have a greater impact than any individual agent. - Highlights: > Ozone exposure, N and base cation deposition modify UK acid grassland composition. > Ozone influences community composition without reducing species richness. > Nitrogen and base cation deposition have interacting impacts. > Distinct species responses to pollutants suggest potential for bioindication. - Ozone exposure and nitrogen deposition have distinct but additive impacts on the plant communities of British acid grasslands.

  4. Impacts of atmospheric pollution on the plant communities of British acid grasslands

    International Nuclear Information System (INIS)

    Payne, Richard J.; Stevens, Carly J.; Dise, Nancy B.; Gowing, David J.; Pilkington, Michael G.; Phoenix, Gareth K.; Emmett, Bridget A.; Ashmore, Michael R.

    2011-01-01

    Air pollutants are recognised as important agents of ecosystem change but few studies consider the effects of multiple pollutants and their interactions. Here we use ordination, constrained cluster analysis and indicator value analyses to identify potential environmental controls on species composition, ecological groupings and indicator species in a gradient study of UK acid grasslands. The community composition of these grasslands is related to climate, grazing, ozone exposure and nitrogen deposition, with evidence for an interaction between the ecological impacts of base cation and nitrogen deposition. Ozone is a key agent in species compositional change but is not associated with a reduction in species richness or diversity indices, showing the subtly different drivers on these two aspects of ecosystem degradation. Our results demonstrate the effects of multiple interacting pollutants, which may collectively have a greater impact than any individual agent. - Highlights: → Ozone exposure, N and base cation deposition modify UK acid grassland composition. → Ozone influences community composition without reducing species richness. → Nitrogen and base cation deposition have interacting impacts. → Distinct species responses to pollutants suggest potential for bioindication. - Ozone exposure and nitrogen deposition have distinct but additive impacts on the plant communities of British acid grasslands.

  5. Understanding the Posttranscriptional Regulation of Plant Responses to Abiotic Stress

    KAUST Repository

    AlShareef, Sahar A.

    2017-06-01

    Constitutive and alternative splicing of pre-mRNAs from multiexonic genes controls the diversity of the proteome; these precisely regulated processes also fine-tune responses to cues related to growth, development, and biotic and abiotic stresses. Recent work showed that AS is pervasive across plant species, with more than 60% of intron-containing genes producing different isoforms. Mammalian cell-based assays have discovered various AS small-molecule inhibitors that perturb splicing and thereby provide invaluable tools for use as chemical probes to uncover the molecular underpinnings of splicing regulation and as potential anticancer compounds. Here, I show that the macrolide Pladienolide B (PB) and herboxidiene (GEX1A) inhibits both constitutive and alternative splicing, mimics an abiotic stress signal, and activates the abscisic acid (ABA) pathway in plants. Moreover, PB and GEX1A activate genome-wide transcriptional patterns involved in abiotic stress responses in plants. PB and GEX1A treatment triggered the ABA signaling pathway, activated ABA-inducible promoters, and led to stomatal closure. Interestingly, PB and GEX1A elicited similar cellular changes, including alterations in the patterns of transcription and splicing, suggesting that these compounds might target the same spliceosome complex in plant cells. This work establishes PB and GEX1A as potent splicing inhibitors in plants that can be used to probe the assembly, dynamics, and molecular functions of the spliceosome and to study the interplay between splicing stress and abiotic stresses, as well as having potential biotechnological applications.

  6. Assessing Cd-induced stress from plant spectral response

    Science.gov (United States)

    Kancheva, Rumiana; Georgiev, Georgi

    2014-10-01

    Remote sensing plays a significant role in local, regional and global monitoring of land covers. Ecological concerns worldwide determine the importance of remote sensing applications for the assessment of soil conditions, vegetation health and identification of stress-induced changes. The extensive industrial growth and intensive agricultural land-use arise the serious ecological problem of environmental pollution associated with the increasing anthropogenic pressure on the environment. Soil contamination is a reason for degradation processes and temporary or permanent decrease of the productive capacity of land. Heavy metals are among the most dangerous pollutants because of their toxicity, persistent nature, easy up-take by plants and long biological half-life. This paper takes as its focus the study of crop species spectral response to Cd pollution. Ground-based experiments were performed, using alfalfa, spring barley and pea grown in Cd contaminated soils and in different hydroponic systems under varying concentrations of the heavy metal. Cd toxicity manifested itself by inhibition of plant growth and synthesis of photosynthetic pigments. Multispectral reflectance, absorbance and transmittance, as well as red and far red fluorescence were measured and examined for their suitability to detect differences in plant condition. Statistical analysis was performed and empirical relationships were established between Cd concentration, plant growth variables and spectral response Various spectral properties proved to be indicators of plant performance and quantitative estimators of the degree of the Cd-induced stress.

  7. Karrikins Identified in Biochars Indicate Post-Fire Chemical Cues Can Influence Community Diversity and Plant Development.

    Directory of Open Access Journals (Sweden)

    Jitka Kochanek

    Full Text Available Karrikins are smoke-derived compounds that provide strong chemical cues to stimulate seed germination and seedling growth. The recent discovery in Arabidopsis that the karrikin perception system may be present throughout angiosperms implies a fundamental plant function. Here, we identify the most potent karrikin, karrikinolide (KAR1, in biochars and determine its role in species unique plant responses.Biochars were prepared by three distinct commercial-scale pyrolysis technologies using systematically selected source material and their chemical properties, including karrikinolide, were quantified. Dose-response assays determined the effects of biochar on seed germination for two model species that require karrikinolide to break dormancy (Solanum orbiculatum, Brassica tourneforttii and on seedling growth using two species that display plasticity to karrikins, biochar and phytotoxins (Lactuca sativa, Lycopersicon esculentum. Multivariate analysis examined relationships between biochar properties and the plant phenotype.Results showed that karrikin abundant biochars stimulated dormant seed germination and seedling growth via mechanisms analogous to post-fire chemical cues. The individual species response was associated with its sensitivity to karrikinolide and inhibitory compounds within the biochars. These findings are critical for understanding why biochar influences community composition and plant physiology uniquely for different species and reaffirms that future pyrolysis technologies promise by-products that concomitantly sequester carbon and enhance plant growth for ecological and broader plant related applications.

  8. Nectar-living yeasts of a tropical host plant community: diversity and effects on community-wide floral nectar traits

    Science.gov (United States)

    2017-01-01

    We characterize the diversity of nectar-living yeasts of a tropical host plant community at different hierarchical sampling levels, measure the associations between yeasts and nectariferous plants, and measure the effect of yeasts on nectar traits. Using a series of hierarchically nested sampling units, we extracted nectar from an assemblage of host plants that were representative of the diversity of life forms, flower shapes, and pollinator types in the tropical area of Yucatan, Mexico. Yeasts were isolated from single nectar samples; their DNA was identified, the yeast cell density was estimated, and the sugar composition and concentration of nectar were quantified using HPLC. In contrast to previous studies from temperate regions, the diversity of nectar-living yeasts in the plant community was characterized by a relatively high number of equally common species with low dominance. Analyses predict highly diverse nectar yeast communities in a relatively narrow range of tropical vegetation, suggesting that the diversity of yeasts will increase as the number of sampling units increases at the level of the species, genera, and botanical families of the hosts. Significant associations between specific yeast species and host plants were also detected; the interaction between yeasts and host plants impacted the effect of yeast cell density on nectar sugars. This study provides an overall picture of the diversity of nectar-living yeasts in tropical host plants and suggests that the key factor that affects the community-wide patterns of nectar traits is not nectar chemistry, but rather the type of yeasts interacting with host plants. PMID:28717591

  9. Nectar-living yeasts of a tropical host plant community: diversity and effects on community-wide floral nectar traits

    Directory of Open Access Journals (Sweden)

    Azucena Canto

    2017-07-01

    Full Text Available We characterize the diversity of nectar-living yeasts of a tropical host plant community at different hierarchical sampling levels, measure the associations between yeasts and nectariferous plants, and measure the effect of yeasts on nectar traits. Using a series of hierarchically nested sampling units, we extracted nectar from an assemblage of host plants that were representative of the diversity of life forms, flower shapes, and pollinator types in the tropical area of Yucatan, Mexico. Yeasts were isolated from single nectar samples; their DNA was identified, the yeast cell density was estimated, and the sugar composition and concentration of nectar were quantified using HPLC. In contrast to previous studies from temperate regions, the diversity of nectar-living yeasts in the plant community was characterized by a relatively high number of equally common species with low dominance. Analyses predict highly diverse nectar yeast communities in a relatively narrow range of tropical vegetation, suggesting that the diversity of yeasts will increase as the number of sampling units increases at the level of the species, genera, and botanical families of the hosts. Significant associations between specific yeast species and host plants were also detected; the interaction between yeasts and host plants impacted the effect of yeast cell density on nectar sugars. This study provides an overall picture of the diversity of nectar-living yeasts in tropical host plants and suggests that the key factor that affects the community-wide patterns of nectar traits is not nectar chemistry, but rather the type of yeasts interacting with host plants.

  10. Growth Response and Tolerance to Heavy Metals of two Swamp Species inoculated with a Plant Growth-Promoting Rhizobacteria

    International Nuclear Information System (INIS)

    Rodriguez-Dorantes, A.; Labra-Cardon, D.; Guerrero-Zuniga, A.; Montes-Villafan, S.

    2009-01-01

    Due to the sensitivity and the sequestration ability of the microbial communities to heavy metals, microbes have been used for bioremediation. Recently the application of plant growth-promoting rhizobacteria (PGPR) for the bioremediation of this kind of contaminants has been done. This study evaluated the growth response and the tolerance to heavy metals of two swamp species. (Author)

  11. Signalling network construction for modelling plant defence response.

    Directory of Open Access Journals (Sweden)

    Dragana Miljkovic

    Full Text Available Plant defence signalling response against various pathogens, including viruses, is a complex phenomenon. In resistant interaction a plant cell perceives the pathogen signal, transduces it within the cell and performs a reprogramming of the cell metabolism leading to the pathogen replication arrest. This work focuses on signalling pathways crucial for the plant defence response, i.e., the salicylic acid, jasmonic acid and ethylene signal transduction pathways, in the Arabidopsis thaliana model plant. The initial signalling network topology was constructed manually by defining the representation formalism, encoding the information from public databases and literature, and composing a pathway diagram. The manually constructed network structure consists of 175 components and 387 reactions. In order to complement the network topology with possibly missing relations, a new approach to automated information extraction from biological literature was developed. This approach, named Bio3graph, allows for automated extraction of biological relations from the literature, resulting in a set of (component1, reaction, component2 triplets and composing a graph structure which can be visualised, compared to the manually constructed topology and examined by the experts. Using a plant defence response vocabulary of components and reaction types, Bio3graph was applied to a set of 9,586 relevant full text articles, resulting in 137 newly detected reactions between the components. Finally, the manually constructed topology and the new reactions were merged to form a network structure consisting of 175 components and 524 reactions. The resulting pathway diagram of plant defence signalling represents a valuable source for further computational modelling and interpretation of omics data. The developed Bio3graph approach, implemented as an executable language processing and graph visualisation workflow, is publically available at http://ropot.ijs.si/bio3graph/and can be

  12. Physiological and biochemical responses of thyme plants to some antioxidants

    Directory of Open Access Journals (Sweden)

    SALWA A. ORABI

    2014-11-01

    Full Text Available Orabi SA, Talaat IM, Balbaa LK. 2014. Physiological and biochemical responses of thyme plants to some antioxidants. Nusantara Bioscience 6: 118-125. Two pot experiments were conducted to investigate the effect of tryptophan, nicotinamide and α-tocopherol (each at 50 and 100 mg/L on plant growth, essential oil yield and its main constituents. All treatments significantly promoted plant height, and increased fresh and dry mass (g/plant of thyme (Thymus vulgaris L.. The treatment with 100 mg/L nicotinamide showed increasing in total potassium mainly in the first cut. Total soluble sugars, oil percentage and oil yield and protein recorded increments with tryptophan treatments. Treatment of Thymus plants with 100 mg/L nicotinamide observed the highest percentage of thymol (67.61%. Oxygenated compounds recorded the highest value with 50 mg/L α-tocopherol treatment, while the maximum non-oxygenated ones resulted from the application of 100 mg/L nicotinamide. All treatments under study significantly affected the activity of oxidoreductase enzymes (POX and PPO. Nicotinamide at the concentration of 100 mg/L recorded the highest increments in APX and GR and the lowest values in oxidoreductase enzyme activities added to the lowest values of lipid peroxidation to enhance the best protection of thyme plants.

  13. Seismic response analysis for a deeply embedded nuclear power plant

    International Nuclear Information System (INIS)

    Chen, W.W.H.; Chatterjee, M.; Day, S.M.

    1979-01-01

    One of the important aspect of the aseimic design of nuclear power plants is the evaluation of the seismic soil-structure interaction effect due to design earthquakes. The soil-structure interaction effect can initiate rocking and result in different soil motions compared to the free field motions, thus significantly affecting the structural response. Two methods are generally used to solve the seismic soil-structure interaction problems: the direct finite element method (FLUSH) and the substructure or impedance approach. This paper presents the results of the horizontal seismic soil-structure interaction analysis using the impedance aproach and the direct finite element method for a deeply embedded nuclear power plant. (orig.)

  14. Response of plant species to coal-mine soil materials

    Energy Technology Data Exchange (ETDEWEB)

    Day, A.D.; Tucker, T.C.; Thames, J.L.

    1983-03-01

    The two-year Black Mesa Coal Mine Research Study on the area near Kayenta, Arizona investigating the growth and establishment of seven plant species in unmined soil and coal-mined soils found that plant species grew better in unmined soil and that irrigation is essential during seedling establishment for the effective stabilization of coal-mined soils in a semi-arid environment. Differences among the species included variations in germination, response to irrigation, seedling establishment, and stem growth. 12 references, 2 figures, 2 tables.

  15. In response to community violence: coping strategies and involuntary stress responses among Latino adolescents.

    Science.gov (United States)

    Epstein-Ngo, Quyen; Maurizi, Laura K; Bregman, Allyson; Ceballo, Rosario

    2013-01-01

    Among poor, urban adolescents, high rates of community violence are a pressing public health concern. This study relies on a contextual framework of stress and coping to investigate how coping strategies and involuntary stress responses may both mediate and moderate the relation between exposure to community violence and psychological well-being. Our sample consists of 223 ninth grade Latino adolescents from poor, urban families. In response to community violence, these adolescents reported using an array of coping strategies as well as experiencing a number of involuntary stress responses; the most frequent coping responses were turning to religion and seeking social support. Hierarchical regression analyses demonstrated that involuntary stress responses mediated the relations between both witnessing or being victimized by violence and poorer psychological functioning, while coping strategies moderated these relations. These findings suggest that the negative psychological effects of exposure to community violence may, in part, be explained by involuntary stress responses, while religious-based coping may serve as a protective factor.

  16. Notification: Hotline Complaint – Drinking Water Treatment Plant at the Fort Belknap Indian Community

    Science.gov (United States)

    Project #OA-FY13-0076, November 13, 2012. On March 22, 2012, the Office of Inspector General (OIG) received a hotline complaint on the construction of the Drinking Water Treatment Plant (DWTP) at the Fort Belknap Indian Community.

  17. Large grazers modify effects of aboveground-belowground interactions on small-scale plant community composition

    NARCIS (Netherlands)

    Veen, G. F. (Ciska); Geuverink, Elzemiek; Olff, Han; Schmid, Bernhard

    Aboveground and belowground organisms influence plant community composition by local interactions, and their scale of impact may vary from millimeters belowground to kilometers aboveground. However, it still poorly understood how large grazers that select their forage on large spatial scales

  18. Large grazers modify effects of aboveground–belowground interactions on small-scale plant community composition

    NARCIS (Netherlands)

    Veen, G.F.; Geuverink, E.; Olff, H.

    2012-01-01

    Aboveground and belowground organisms influence plant community composition by local interactions, and their scale of impact may vary from millimeters belowground to kilometers aboveground. However, it still poorly understood how large grazers that select their forage on large spatial scales

  19. Drivers of spatial heterogeneity in nitrogen processing among three alpine plant communities in the Rocky Mountains

    Science.gov (United States)

    Churchill, A. C.; Beers, A.; Grinath, J.; Bowman, W. D.

    2017-12-01

    Nitrogen cycling across the globe has been fundamentally altered due to regional elevated N deposition and there is a cascade of ecosystem consequences including shifts in species composition, eutrophication, and soil acidification. Making predictions that encompass the factors that drive these ecosystem changes has frequently been limited to single ecosystem types, or areas with fairly homogenous abiotic conditions. The alpine is an ecosystem type that exhibits changes under relatively low levels of N depositions due to short growing seasons and shallow soils limiting N storage. While recent work provided estimates for the magnitude of N associated with ecosystem changes, less is known about the within-site factors that may interact to stabilize or amplify the differential response of N pools under future conditions of resource deposition. To examine numerous potential within-site and regional factors (both biotic and abiotic) affecting ecosystem N pools we examined the relationship between those factors and a suite of ecosystem pools of N followed by model selection procedures and structural equation modelling. Measurements were conducted at Niwot Ridge Long Term Ecological Research site and in Rocky Mountain National Park in three distinct alpine meadow ecosystems (dry, moist, and wet meadows). These meadows span a moisture gradient as well as plant community composition, thereby providing high variability of potential biotic and abiotic drivers across small spatial scales in the alpine. In general, regional scale abiotic factors such as site levels of annual average N deposition or precipitation were poor predictors of seasonal pools of N, while spring soil water pools of N were negatively correlated with elevation. Models containing multiple abiotic and biotic drivers, however, were best at predicting soil and plant pools of N across the two sites. Future analysis will include highlight interactions among with-site factors affecting N pools in the alpine using

  20. Plant Nucleolar Stress Response, a New Face in the NAC-Dependent Cellular Stress Responses.

    Science.gov (United States)

    Ohbayashi, Iwai; Sugiyama, Munetaka

    2017-01-01

    The nucleolus is the most prominent nuclear domain, where the core processes of ribosome biogenesis occur vigorously. All these processes are finely orchestrated by many nucleolar factors to build precisely ribosome particles. In animal cells, perturbations of ribosome biogenesis, mostly accompanied by structural disorders of the nucleolus, cause a kind of cellular stress to induce cell cycle arrest, senescence, or apoptosis, which is called nucleolar stress response. The best-characterized pathway of this stress response involves p53 and MDM2 as key players. p53 is a crucial transcription factor that functions in response to not only nucleolar stress but also other cellular stresses such as DNA damage stress. These cellular stresses release p53 from the inhibition by MDM2, an E3 ubiquitin ligase targeting p53, in various ways, which leads to p53-dependent activation of a set of genes. In plants, genetic impairments of ribosome biogenesis factors or ribosome components have been shown to cause characteristic phenotypes, including a narrow and pointed leaf shape, implying a common signaling pathway connecting ribosomal perturbations and certain aspects of growth and development. Unlike animals, however, plants have neither p53 nor MDM2 family proteins. Then the question arises whether plant cells have a nucleolar stress response pathway. In recent years, it has been reported that several members of the plant-specific transcription factor family NAC play critical roles in the pathways responsive to various cellular stresses. In this mini review, we outline the plant cellular stress response pathways involving NAC transcription factors with reference to the p53-MDM2-dependent pathways of animal cells, and discuss the possible involvement of a plant-unique, NAC-mediated pathway in the nucleolar stress response in plants.

  1. Plant Nucleolar Stress Response, a New Face in the NAC-Dependent Cellular Stress Responses

    Directory of Open Access Journals (Sweden)

    Iwai Ohbayashi

    2018-01-01

    Full Text Available The nucleolus is the most prominent nuclear domain, where the core processes of ribosome biogenesis occur vigorously. All these processes are finely orchestrated by many nucleolar factors to build precisely ribosome particles. In animal cells, perturbations of ribosome biogenesis, mostly accompanied by structural disorders of the nucleolus, cause a kind of cellular stress to induce cell cycle arrest, senescence, or apoptosis, which is called nucleolar stress response. The best-characterized pathway of this stress response involves p53 and MDM2 as key players. p53 is a crucial transcription factor that functions in response to not only nucleolar stress but also other cellular stresses such as DNA damage stress. These cellular stresses release p53 from the inhibition by MDM2, an E3 ubiquitin ligase targeting p53, in various ways, which leads to p53-dependent activation of a set of genes. In plants, genetic impairments of ribosome biogenesis factors or ribosome components have been shown to cause characteristic phenotypes, including a narrow and pointed leaf shape, implying a common signaling pathway connecting ribosomal perturbations and certain aspects of growth and development. Unlike animals, however, plants have neither p53 nor MDM2 family proteins. Then the question arises whether plant cells have a nucleolar stress response pathway. In recent years, it has been reported that several members of the plant-specific transcription factor family NAC play critical roles in the pathways responsive to various cellular stresses. In this mini review, we outline the plant cellular stress response pathways involving NAC transcription factors with reference to the p53-MDM2-dependent pathways of animal cells, and discuss the possible involvement of a plant-unique, NAC-mediated pathway in the nucleolar stress response in plants.

  2. The Community's research and development programme on decommissioning of nuclear power plants

    International Nuclear Information System (INIS)

    1982-01-01

    The programme, adopted by the Council of the European Communities, seeks to promote a number of research and development projects as well as the identification of guiding principles. The projects concern the following subjects: long-term integrity of buildings and systems; decontaminations for decommissioning purposes; dismantling techniques; treatment of specific waste materials (steel, concrete and graphite); large transport containers for radioactive waste arising from decommissioning of nuclear power plants in the Community; and influence of nuclear power plant design features on decommissioning

  3. Relationships between phyllosphere bacterial communities and plant functional traits in a neotropical forest

    Science.gov (United States)

    Kembel, Steven W.; O’Connor, Timothy K.; Arnold, Holly K.; Hubbell, Stephen P.; Wright, S. Joseph; Green, Jessica L.

    2014-01-01

    The phyllosphere—the aerial surfaces of plants, including leaves—is a ubiquitous global habitat that harbors diverse bacterial communities. Phyllosphere bacterial communities have the potential to influence plant biogeography and ecosystem function through their influence on the fitness and function of their hosts, but the host attributes that drive community assembly in the phyllosphere are poorly understood. In this study we used high-throughput sequencing to quantify bacterial community structure on the leaves of 57 tree species in a neotropical forest in Panama. We tested for relationships between bacterial communities on tree leaves and the functional traits, taxonomy, and phylogeny of their plant hosts. Bacterial communities on tropical tree leaves were diverse; leaves from individual trees were host to more than 400 bacterial taxa. Bacterial communities in the phyllosphere were dominated by a core microbiome of taxa including Actinobacteria, Alpha-, Beta-, and Gammaproteobacteria, and Sphingobacteria. Host attributes including plant taxonomic identity, phylogeny, growth and mortality rates, wood density, leaf mass per area, and leaf nitrogen and phosphorous concentrations were correlated with bacterial community structure on leaves. The relative abundances of several bacterial taxa were correlated with suites of host plant traits related to major axes of plant trait variation, including the leaf economics spectrum and the wood density–growth/mortality tradeoff. These correlations between phyllosphere bacterial diversity and host growth, mortality, and function suggest that incorporating information on plant–microbe associations will improve our ability to understand plant functional biogeography and the drivers of variation in plant and ecosystem function. PMID:25225376

  4. The effect of environmental change on vascular plant and cryptogam communities from the Falkland Islands and the Maritime Antarctic

    Directory of Open Access Journals (Sweden)

    Convey Peter

    2007-12-01

    Full Text Available Abstract Background Antarctic terrestrial vegetation is subject to one of the most extreme climates on Earth. Currently, parts of Antarctica are one of the fastest warming regions on the planet. During 3 growing seasons, we investigated the effect of experimental warming on the diversity and abundance of coastal plant communities in the Maritime Antarctic region (cryptogams only and the Falkland Islands (vascular plants only. We compared communities from the Falkland Islands (51°S, mean annual temperature 7.9°C, with those of Signy Island (60°S, -2.1°C and Anchorage Island (67°S, -2.6°C, and experimental temperature manipulations at each of the three islands using Open Top Chambers (OTCs. Results Despite the strong difference in plant growth form dominance between the Falkland Islands and the Maritime Antarctic, communities across the gradient did not differ in total diversity and species number. During the summer months, the experimental temperature increase at 5 cm height in the vegetation was similar between the locations (0.7°C across the study. In general, the response to this experimental warming was low. Total lichen cover showed a non-significant decreasing trend at Signy Island (p Conclusion These results suggest that small temperature increases may rapidly lead to decreased soil moisture, resulting in more stressful conditions for plants. The more open plant communities (grass and lichen appeared more negatively affected by such changes than dense communities (dwarf shrub and moss.

  5. Belowground Carbon Allocation and Plant-Microbial Interactions Drive Resistance and Resilience of Mountain Grassland Communities to Drought

    Science.gov (United States)

    Karlowsky, S.; Augusti, A.; Ingrisch, J.; Hasibeder, R.; Lavorel, S.; Bahn, M.; Gleixner, G.

    2016-12-01

    Belowground carbon allocation (BCA) and plant-microbial interactions are crucial for the functioning of terrestrial ecosystems. Recent research suggests that extreme events can have severe effects on these processes but it is unknown how land use intensity potentially modifies their responses. We studied the resistance and resilience of mountain grassland communities to prolonged drought and investigated the role of plant C allocation and soil microbial communities in mediating drought resistance and immediate recovery. In a common garden experiment we exposed monoliths from an abandoned grassland and a hay meadow to an early summer drought. Two independent 13C pulse labeling experiments were conducted, the first during peak drought and the second during the recovery phase. The 13C incorporation was analyzed in above- and belowground plant parts and in phospho- and neutral lipid fatty acids of soil microorganisms. In addition, a 15N label was added at the rewetting to determine plant N uptake. We found that C uptake, BCA and C transfer to soil microorganisms were less strongly reduced by drought in the abandoned grassland than in the meadow. Moreover, drought induced an increase of arbuscular mycorrhiza fungi (AMF) marker in the abandoned grassland. Nevertheless, C uptake and related parameters were quickly recovered and N uptake increased in the meadow during recovery. Unexpectedly, AMF and their C uptake were generally reduced during recovery, while bacteria increased and quickly recovered C uptake, particularly in the meadow. Our results showed a negative relation between high resistance and fast recovery. The more resistant abandoned grassland plant communities seemed to invest more C below ground and into interactions with AMF during drought, likely to access water through their hyphal network. Conversely, meadow communities invested more C from recent photosynthesis into bacterial communities during recovery, obviously to gain more nutrients for regrowth

  6. Volatile-Mediated within-Plant Signaling in Hybrid Aspen: Required for Systemic Responses.

    Science.gov (United States)

    Li, Tao; Blande, James D

    2017-04-01

    Plant volatiles play crucial roles in signaling between plants and their associated community members, but their role in within-plant signaling remains largely unexplored, particularly under field conditions. Using a system comprising the hybrid aspen (Populus tremula x tremuloides) and the specialized herbivorous leaf beetle (Phratora laticollis) and, combining field, greenhouse and laboratory experiments, we examined whether local damage triggered systemic responses in undamaged branches that lack vascular connection to the damaged branches, and to what extent this was caused by airborne volatile signals versus internal signals. An experiment tracing dye through the vasculature of saplings revealed no downward movement of the dye from upper to lower branches, suggesting a lack of vascular connectivity among branches. However, we found under both field and laboratory conditions that herbivore feeding on upper branches elicited volatile emissions by undamaged lower branches. Greenhouse experiments manipulating air contact between damaged and undamaged branches showed that systemic induction of volatiles was almost eliminated when air contact was interrupted. Our findings clearly demonstrate that herbivore-induced volatiles overcome vascular constraints and mediate within-plant signaling. Further, we found that volatile signaling led to induction of different classes of volatiles under field and environment controlled conditions, with a weaker response observed in the field. This difference not only reflects the dose- and time-dependent nature of volatile signaling, but also points out that future studies should focus more on field observations to better understand the ecological role of volatile-mediated within-plant signaling.

  7. Responses of plant nutrient resorption to phosphorus addition in freshwater marsh of Northeast China

    Science.gov (United States)

    Mao, Rong; Zeng, De-Hui; Zhang, Xin-Hou; Song, Chang-Chun

    2015-01-01

    Anthropogenic activities have increased phosphorus (P) inputs to most aquatic and terrestrial ecosystems. However, the relationship between plant nutrient resorption and P availability is still unclear, and much less is known about the underlying mechanisms. Here, we used a multi-level P addition experiment (0, 1.2, 4.8, and 9.6 g P m−2 year−1) to assess the effect of P enrichment on nutrient resorption at plant organ, species, and community levels in a freshwater marsh of Northeast China. The response of nutrient resorption to P addition generally did not vary with addition rates. Moreover, nutrient resorption exhibited similar responses to P addition across the three hierarchical levels. Specifically, P addition decreased nitrogen (N) resorption proficiency, P resorption efficiency and proficiency, but did not impact N resorption efficiency. In addition, P resorption efficiency and proficiency were linearly related to the ratio of inorganic P to organic P and organic P fraction in mature plant organs, respectively. Our findings suggest that the allocation pattern of plant P between inorganic and organic P fractions is an underlying mechanism controlling P resorption processes, and that P enrichment could strongly influence plant-mediated biogeochemical cycles through altered nutrient resorption in the freshwater wetlands of Northeast China. PMID:25631373

  8. Rapid plant evolution in the presence of an introduced species alters community composition.

    Science.gov (United States)

    Smith, David Solance; Lau, Matthew K; Jacobs, Ryan; Monroy, Jenna A; Shuster, Stephen M; Whitham, Thomas G

    2015-10-01

    Because introduced species may strongly interact with native species and thus affect their fitness, it is important to examine how these interactions can cascade to have ecological and evolutionary consequences for whole communities. Here, we examine the interactions among introduced Rocky Mountain elk, Cervus canadensis nelsoni, a common native plant, Solidago velutina, and the diverse plant-associated community of arthropods. While introduced species are recognized as one of the biggest threats to native ecosystems, relatively few studies have investigated an evolutionary mechanism by which introduced species alter native communities. Here, we use a common garden design that addresses and supports two hypotheses. First, native S. velutina has rapidly evolved in the presence of introduced elk. We found that plants originating from sites with introduced elk flowered nearly 3 weeks before plants originating from sites without elk. Second, evolution of S. velutina results in a change to the plant-associated arthropod community. We found that plants originating from sites with introduced elk supported an arthropod community that had ~35 % fewer total individuals and a different species composition. Our results show that the impacts of introduced species can have both ecological and evolutionary consequences for strongly interacting species that subsequently cascade to affect a much larger community. Such evolutionary consequences are likely to be long-term and difficult to remediate.

  9. Seed bank and big sagebrush plant community composition in a range margin for big sagebrush

    Science.gov (United States)

    Martyn, Trace E.; Bradford, John B.; Schlaepfer, Daniel R.; Burke, Ingrid C.; Laurenroth, William K.

    2016-01-01

    The potential influence of seed bank composition on range shifts of species due to climate change is unclear. Seed banks can provide a means of both species persistence in an area and local range expansion in the case of increasing habitat suitability, as may occur under future climate change. However, a mismatch between the seed bank and the established plant community may represent an obstacle to persistence and expansion. In big sagebrush (Artemisia tridentata) plant communities in Montana, USA, we compared the seed bank to the established plant community. There was less than a 20% similarity in the relative abundance of species between the established plant community and the seed bank. This difference was primarily driven by an overrepresentation of native annual forbs and an underrepresentation of big sagebrush in the seed bank compared to the established plant community. Even though we expect an increase in habitat suitability for big sagebrush under future climate conditions at our sites, the current mismatch between the plant community and the seed bank could impede big sagebrush range expansion into increasingly suitable habitat in the future.

  10. Exploring mHealth Participation for Emergency Response Communities

    Directory of Open Access Journals (Sweden)

    David G. Schwartz

    2017-03-01

    Full Text Available We explore the challenges of participation by members of emergency response communities who share a similar condition and treatment, and are called upon to participate in emergency events experienced by fellow members. Smartphones and location-based social networking technologies present an opportunity to re-engineer certain aspects of emergency medical response. Life-saving prescription medication extended in an emergency by one individual to another occurs on a micro level, anecdotally documented. We illustrate the issues and our approach through the example of an app to support patients prone to anaphylaxis and prescribed to carry epinephrine auto-injectors. We address unique participation challenges in an mHealth environment in which interventions are primarily short-term interactions which require clear and precise decision-making and constant tracking of potential participants in responding to an emergency medical event. The conflicting effects of diffused responsibility and shared identity are identified as key factors in modeling participation.

  11. Community-Weighted Mean Plant Traits Predict Small Scale Distribution of Insect Root Herbivore Abundance.

    Directory of Open Access Journals (Sweden)

    Ilja Sonnemann

    Full Text Available Small scale distribution of insect root herbivores may promote plant species diversity by creating patches of different herbivore pressure. However, determinants of small scale distribution of insect root herbivores, and impact of land use intensity on their small scale distribution are largely unknown. We sampled insect root herbivores and measured vegetation parameters and soil water content along transects in grasslands of different management intensity in three regions in Germany. We calculated community-weighted mean plant traits to test whether the functional plant community composition determines the small scale distribution of insect root herbivores. To analyze spatial patterns in plant species and trait composition and insect root herbivore abundance we computed Mantel correlograms. Insect root herbivores mainly comprised click beetle (Coleoptera, Elateridae larvae (43% in the investigated grasslands. Total insect root herbivore numbers were positively related to community-weighted mean traits indicating high plant growth rates and biomass (specific leaf area, reproductive- and vegetative plant height, and negatively related to plant traits indicating poor tissue quality (leaf C/N ratio. Generalist Elaterid larvae, when analyzed independently, were also positively related to high plant growth rates and furthermore to root dry mass, but were not related to tissue quality. Insect root herbivore numbers were not related to plant cover, plant species richness and soil water content. Plant species composition and to a lesser extent plant trait composition displayed spatial autocorrelation, which was not influenced by land use intensity. Insect root herbivore abundance was not spatially autocorrelated. We conclude that in semi-natural grasslands with a high share of generalist insect root herbivores, insect root herbivores affiliate with large, fast growing plants, presumably because of availability of high quantities of food. Affiliation of

  12. Comparison of bacterial and fungal communities between natural and planted pine forests in subtropical China.

    Science.gov (United States)

    Nie, Ming; Meng, Han; Li, Ke; Wan, Jia-Rong; Quan, Zhe-Xue; Fang, Chang-Ming; Chen, Jia-Kuan; Li, Bo

    2012-01-01

    To improve our understanding of the changes in bacterial and fungal diversity in natural pine and planted forests in subtropical region of China, we examined bacterial and fungal communities from a native and a nearby planted pine forest of the Mt. Lushan by constructing clone libraries of 16S and 18S rRNA genes. For bacterial communities, Proteobacteria and Acidobacteria were dominant bacterial taxa in both two types of forest soils. The Shannon-Wiener diversity index, rarefaction curve analysis, and LibShuff analysis suggest that these two forests contained similar diversity of bacterial communities. Low soil acidity (pH ≈ 4) of our study forests might be one of the most important selection factors determining growth of acidophilic Acidobacteria and Proteobacteria. However, the natural forest harbored greater level of fungal diversity than the planted forest according to the Shannon-Wiener diversity index and rarefaction curve analysis. Basidiomycota and Ascomycota were dominant fungal taxa in the soils of natural and planted forests, respectively. Our results suggest that fungal community was more sensitive than the bacterial community in characterizing the differences in plant cover impacts on the microbial flora in the natural and planted forests. The natural and planted forests may function differently due to the differences in soil fungal diversity and relative abundance.

  13. Plant genotype shapes ant-aphid interactions: implications for community structure and indirect plant defense.

    Science.gov (United States)

    Mooney, Kailen A; Agrawal, Anurag A

    2008-06-01

    Little is known about the mechanisms by which plant genotype shapes arthropod community structure. In a field experiment, we measured the effects of milkweed (Asclepias syriaca) genotype and ants on milkweed arthropods. Populations of the ant-tended aphid Aphis asclepiadis and the untended aphid Myzocallis asclepiadis varied eight- to 18-fold among milkweed genotypes, depending on aphid species and whether ants were present. There was no milkweed effect on predatory arthropods. Ants increased Aphis abundance 59%, decreased Myzocallis abundance 52%, and decreased predator abundance 56%. Milkweed genotype indirectly influenced ants via direct effects on Aphis and Myzocallis abundance. Milkweed genotype also modified ant-aphid interactions, influencing the number of ants attracted per Aphis and Myzocallis. While ant effects on Myzocallis were consistently negative, effects on Aphis ranged from antagonistic to mutualistic among milkweed genotypes. As a consequence of milkweed effects on ant-aphid interactions, ant abundance varied 13-fold among milkweed genotypes, and monarch caterpillar survival was negatively correlated with genetic variation in ant abundance. We speculate that heritable variation in milkweed phloem sap drives these effects on aphids, ants, and caterpillars. In summary, milkweed exerts genetic control over the interactions between aphids and an ant that provides defense against foliage-feeding caterpillars.

  14. Species richness and floristic composition of Choco Region plant communities Species richness and floristic composition of Choco Region plant communities

    Directory of Open Access Journals (Sweden)

    Gentry Alwyn H.

    1986-12-01

    Full Text Available The Chocó phytogeographical region of coastal Colombia and adjacent Ecuador is well known as a region of unusually high endemism in plants (GENTRY, 1982a, 1986b, birds (TERBORGH & WINTER, 1982, and butterflies (BROWN, 1975, 1982. The region is also reputed to be unusually diverse biologically (GENTRY, 1978, 1982a but much of the data base for this assumption is rather anecdotal and for birds and heliconiinae butterflies (probably the best known groups of organisms it is clear that faunistic community diversity of the coastal Chocó is substantially less than in much of upper Amazonia (J. TERBORGH, pers. comm., K. BROWN, pers. comm.. El Choco la región fitogeográfica de la costa de Colombia y adyacente al Ecuador es conocido como una región de inusualmente alto endemismo en plantas (Gentry, 1982a, 1986b, pájaros (Terborgh y Winter, 1982, y las mariposas (Brown, 1975, 1982. La región también es conocida por ser inusualmente diversa biológicamente (Gentry, 1978, 1982a, pero gran parte de la base de datos para estesuposición es bastante anecdótico y para las aves y mariposas Heliconiinae (prooably los grupos más conocidos de organismos, está claro que la diversidad faunística comunidad del Chaco costera es sustancialmente menor que en gran parte de la Amazonia superior (J. Terborgh, com. pers., K . BROWN, com. pers..El único dato de nivel comunitario disponible para las plantas de la costa Colombia es la forma incompleta analizado 1000 m2 muestra de todas las plantas de más de2.5 cm dbh procedente de Tutunendó, incluido en Gentry (1982b de los patrones de diversidad neotropicales. Choco muestra de Gentry tenía el más alto número de especies de una serie de sitios de muestra y similares que llegaron a la conclusión de que nivel de riqueza de especies vegetales comunidad aumenta directamente con la precipitación. Muchos 1.000 m2 adicionales están disponibles, tanto desde el Chocoregión y de las especies ricas en bosques de Alto

  15. Purple pitcher plant (Sarracenia rosea Dieback and partial community disassembly following experimental storm surge in a coastal pitcher plant bog.

    Directory of Open Access Journals (Sweden)

    Matthew J Abbott

    Full Text Available Sea-level rise and frequent intense hurricanes associated with climate change will result in recurrent flooding of inland systems such as Gulf Coastal pitcher plant bogs by storm surges. These surges can transport salt water and sediment to freshwater bogs, greatly affecting their biological integrity. Purple pitcher plants (Sarracenia rosea are Gulf Coast pitcher plant bog inhabitants that could be at a disadvantage under this scenario because their pitcher morphology may leave them prone to collection of saline water and sediment after a surge. We investigated the effects of storm surge water salinity and sediment type on S. rosea vitality, plant community structure, and bog soil-water conductivity. Plots (containing ≥1 ramet of S. rosea were experimentally flooded with fresh or saline water crossed with one of three sediment types (local, foreign, or no sediment. There were no treatment effects on soil-water conductivity; nevertheless, direct exposure to saline water resulted in significantly lower S. rosea cover until the following season when a prescribed fire and regional drought contributed to the decline of all the S. rosea to near zero percent cover. There were also significant differences in plant community structure between treatments over time, reflecting how numerous species increased in abundance and a few species decreased in abundance. However, in contrast to S. rosea, most of the other species in the community appeared resilient to the effects of storm surge. Thus, although the community may be somewhat affected by storm surge, those few species that are particularly sensitive to the storm surge disturbance will likely drop out of the community and be replaced by more resilient species. Depending on the longevity of these biological legacies, Gulf Coastal pitcher plant bogs may be incapable of fully recovering if they become exposed to storm surge more frequently due to climate change.

  16. Plant Communities Rather than Soil Properties Structure Arbuscular Mycorrhizal Fungal Communities along Primary Succession on a Mine Spoil

    Czech Academy of Sciences Publication Activity Database

    Krüger, C.; Kohout, Petr; Janoušková, M.; Püschel, D.; Frouz, J.; Rydlová, J.

    2017-01-01

    Roč. 8, APR 20 (2017), s. 1-16, č. článku 719. ISSN 1664-302X Institutional support: RVO:61388971 Keywords : biodiversity * community ecology * fungal and plant succession Subject RIV: EE - Microbiology, Virology OBOR OECD: Microbiology Impact factor: 4.076, year: 2016

  17. Earthworms drive succession of both plant and Collembola communities in post-mining sites

    Czech Academy of Sciences Publication Activity Database

    Mudrák, Ondřej; Uteseny, Karoline; Frouz, Jan

    2016-01-01

    Roč. 18, April (2016), EGU2016-8464 ISSN 1607-7962. [European Geosciences Union General Assembly 2016. 17.04.2016-22.04.2016, Vienna] Institutional support: RVO:60077344 ; RVO:67985939 Keywords : earthworms * succession * plant communities * Collembola communities * post-mining sites Subject RIV: DF - Soil Science

  18. Effects of changes in plant species richness and community traits on carabid assemblages and feeding guilds

    NARCIS (Netherlands)

    Harvey, J.A.; Putten, van der W.H.; Turin, H.; Wagenaar, R.; Bezemer, T.M.

    2008-01-01

    Experiments were conducted between 2001 and 2003 in constructed plant communities that were set up in 1996 on abandoned agricultural land. The primary aim of the experiment was to study how different secondary vegetation succession scenarios influence community development of invertebrates in

  19. Plant genetic and molecular responses to water deficit

    Directory of Open Access Journals (Sweden)

    Silvio Salvi

    2011-02-01

    Full Text Available Plant productivity is severely affected by unfavourable environmental conditions (biotic and abiotic stresses. Among others, water deficit is the plant stress condition which mostly limits the quality and the quantity of plant products. Tolerance to water deficit is a polygenic trait strictly dependent on the coordinated expression of a large set of genes coding for proteins directly involved in stress-induced protection/repair mechanisms (dehydrins, chaperonins, enzymes for the synthesis of osmoprotectants and detoxifying compounds, and others as well as genes involved in transducing the stress signal and regulating gene expression (transcription factors, kinases, phosphatases. Recently, research activities in the field evolved from the study of single genes directly involved in cellular stress tolerance (functional genes to the identification and characterization of key regulatory genes involved in stress perception and transduction and able to rapidly and efficiently activate the complex gene network involved in the response to stress. The complexity of the events occurring in response to stress have been recently approached by genomics tools; in fact the analysis of transcriptome, proteome and metabolome of a plant tissue/cell in response to stress already allowed to have a global view of the cellular and molecular events occurring in response to water deficit, by the identification of genes activated and co-regulated by the stress conditions and the characterization of new signalling pathways. Moreover the recent application of forward and reverse genetic approaches, trough mutant collection development, screening and characterization, is giving a tremendous impulse to the identification of gene functions with key role in stress tolerance. The integration of data obtained by high-throughput genomic approaches, by means of powerful informatic tools, is allowing nowadays to rapidly identify of major genes/QTLs involved in stress tolerance

  20. Nanosecond electric pulses trigger actin responses in plant cells

    International Nuclear Information System (INIS)

    Berghoefer, Thomas; Eing, Christian; Flickinger, Bianca; Hohenberger, Petra; Wegner, Lars H.; Frey, Wolfgang; Nick, Peter

    2009-01-01

    We have analyzed the cellular effects of nanosecond pulsed electrical fields on plant cells using fluorescently tagged marker lines in the tobacco cell line BY-2 and confocal laser scanning microscopy. We observe a disintegration of the cytoskeleton in the cell cortex, followed by contraction of actin filaments towards the nucleus, and disintegration of the nuclear envelope. These responses are accompanied by irreversible permeabilization of the plasma membrane manifest as uptake of Trypan Blue. By pretreatment with the actin-stabilizing drug phalloidin, the detachment of transvacuolar actin from the cell periphery can be suppressed, and this treatment can also suppress the irreversible perforation of the plasma membrane. We discuss these findings in terms of a model, where nanosecond pulsed electric fields trigger actin responses that are key events in the plant-specific form of programmed cell death.

  1. Ethnoveterinary medicinal plants used by the Maale and Ari ethnic communities in southern Ethiopia

    NARCIS (Netherlands)

    Kidane, B.; Maesen, van der L.J.G.; Andel, van T.; Asfaw, Z.

    2014-01-01

    Ethnopharmacological relevance: Livestock production is an integral part of the agricultural system in Ethiopia. Medicinal plants are used and are important for rural communities for the treatment of livestock diseases. We studied and analysed the traditional medicinal plants used for the treatment

  2. Competition for light and nutrients in layered communities of aquatic plants

    NARCIS (Netherlands)

    Van Gerven, Luuk P.A.; de Klein, J.J.M; Gerla, Daan J.; Kooi, B.W.; Kuiper, Jan J.; Mooij, Wolf M.

    2015-01-01

    Dominance of free-floating plants poses a threat to biodiversity in many freshwater ecosystems. Here we propose a theoretical framework to understand this dominance, by modeling the competition for light and nutrients in a layered community of floating and submerged plants. The model shows that at

  3. Competition for Light and Nutrients in Layered Communities of Aquatic Plants

    NARCIS (Netherlands)

    van Gerven, L.P.A.; de Klein, J.J.M.; Gerla, D.J.; Kooi, B.W.; Kuiper, J.J.; Mooij, W.M.

    2015-01-01

    Dominance of free-floating plants poses a threat to biodiversity in many freshwater ecosystems. Here we propose a theoretical framework to understand this dominance, by modeling the competition for light and nutrients in a layered community of floating and submerged plants. The model shows that at

  4. Competition for light and nutrients in layered communities of aquatic plants

    NARCIS (Netherlands)

    Gerven, van Luuk P.A.; Klein, de Jeroen J.M.; Gerla, Daan J.; Kooi, Bob W.; Kuiper, Jan J.; Mooij, Wolf M.

    2015-01-01

    Dominance of free-floating plants poses a threat to biodiversity in many freshwater ecosystems. Here we propose a theoretical framework to understand this dominance, by modeling the competition for light and nutrients in a layered community of floating and submerged plants. The model shows that

  5. Hierarchical spatial point process analysis for a plant community with high biodiversity

    DEFF Research Database (Denmark)

    Illian, Janine B.; Møller, Jesper; Waagepetersen, Rasmus

    2009-01-01

    A complex multivariate spatial point pattern of a plant community with high biodiversity is modelled using a hierarchical multivariate point process model. In the model, interactions between plants with different post-fire regeneration strategies are of key interest. We consider initially a maxim...

  6. Microbial Communities in Danish Wastewater Treatment Plants with Nutrient Removal

    DEFF Research Database (Denmark)

    Mielczarek, Artur Tomasz

    Activated sludge treatment plants are the most used wastewater treatment systems worldwide for biological nutrient removal from wastewater. Nevertheless, the treatment systems have been for many years operated as so called “black-box”, where specific process parameters were adjusted without...... that plants with return sludge Side-Stream Hydrolysis (SSH) instead of the normal anaerobic process tank tended to have significantly fewer unwanted GAOs in contrast to many plants with traditional mainstream anaerobic tank and thus it was proposed that this system might be an effective strategy of control...

  7. Unique phytochrome responses of the holoparasitic plant Orobanche minor.

    Science.gov (United States)

    Takagi, Kazuteru; Okazawa, Atsushi; Wada, Yu; Mongkolchaiyaphruek, Anchaya; Fukusaki, Eiichiro; Yoneyama, Koichi; Takeuchi, Yasutomo; Kobayashi, Akio

    2009-06-01

    Holoparasitic plants such as Orobanche spp. have lost their photosynthetic ability, so photoresponses to optimize photosynthesis are not necessary in these plants. Photoresponses are also involved in the regulation of plant development but the photoresponses of holoparasites have not been characterized in detail. In this study, the phytochrome (phy)-related photoresponse of Orobanche minor was investigated. Its photoreceptor, phytochrome A (OmphyA), was also characterized. Light effects on germination, shoot elongation, anthocyanin biosynthesis, and OmphyA expression and subcellular localization were analyzed. Red light (R):far-red light (FR) reversible inhibition of O. minor seed germination demonstrated that phy-mediated responses are retained in this holoparasite. Shoot elongation was inhibited by FR but not by R. This pattern is unique among known patterns of plant photoresponses. Additionally, molecular analysis showed that OmphyA is able to respond to the light signals. Interestingly, the unique pattern of photoresponses in O. minor seems to have been modified for adaptation to its parasitic life cycle. We hypothesize that this alteration has resulted from the loss or alteration of some phy-signaling components. Elucidation of altered components in phy signaling in this parasite will provide useful information not only about its physiological characteristics but also about general plant photoreception systems.

  8. The Venturia Apple Pathosystem: Pathogenicity Mechanisms and Plant Defense Responses

    Directory of Open Access Journals (Sweden)

    Gopaljee Jha

    2009-01-01

    Full Text Available Venturia inaequalis is the causal agent of apple scab, a devastating disease of apple. We outline several unique features of this pathogen which are useful for molecular genetics studies intended to understand plant-pathogen interactions. The pathogenicity mechanisms of the pathogen and overview of apple defense responses, monogenic and polygenic resistance, and their utilization in scab resistance breeding programs are also reviewed.

  9. 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.

    2013-01-01

    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.

  10. Effectors from Wheat Rust Fungi Suppress Multiple Plant Defense Responses.

    Science.gov (United States)

    Ramachandran, Sowmya R; Yin, Chuntao; Kud, Joanna; Tanaka, Kiwamu; Mahoney, Aaron K; Xiao, Fangming; Hulbert, Scot H

    2017-01-01

    Fungi that cause cereal rust diseases (genus Puccinia) are important pathogens of wheat globally. Upon infection, the fungus secretes a number of effector proteins. Although a large repository of putative effectors has been predicted using bioinformatic pipelines, the lack of available high-throughput effector screening systems has limited functional studies on these proteins. In this study, we mined the available transcriptomes of Puccinia graminis and P. striiformis to look for potential effectors that suppress host hypersensitive response (HR). Twenty small (wheat, confirming its activity in a homologous system. Overall, this study provides the first evidence for the presence of effectors in Puccinia species suppressing multiple plant defense responses.

  11. Wetland Plants of Great Salt Lake, A Guide to Identification, Communities, & Bird Habitat

    OpenAIRE

    Downard, Rebekah; Frank, Maureen; Perkins, Jennifer; Kettenring, Karin; Larese-Casanova, Mark

    2017-01-01

    Wetland Plants of Great Salt Lake: a guide to identification, communities, & bird habitat is a wetland plant identification guide, resulting from collaborative research efforts about Great Salt Lake (GSL) wetland conditions and bird habitat. Dr. Rebekah Downard collected dissertation field data from GSL wetlands during 2012–2015, the majority of which informed this work. Dr. Maureen Frank contributed her guide to GSL wetland vegetation and how to manage native plants as high-quality habitat f...

  12. THE CONCENTRATION OF PHOTOSINTHESIS PIGMENTS IN THE ANTHROPOGENIC PLANT COMMUNITIES IN TOBOLSK TOWN

    OpenAIRE

    Еlena Ivanovna Popova

    2016-01-01

    Photosynthesis means a lot in the life of a plant body. For the normal photosynthesis process it is necessary to have certain external and internal conditions. The topic of the research is the study of photosynthesis pigments in anthropogenic plant communities. The aim of our work was to study the pigment composition plants of anthropogenic phytocenoses. Methods: we have used the spectrophotometric method to define the concentration of pigments. Results: the research has shown that the concen...

  13. Unraveling the response of plant cells to cytotoxic saponins

    Science.gov (United States)

    Balestrazzi, Alma; Macovei, Anca; Tava, Aldo; Avato, Pinarosa; Raimondi, Elena

    2011-01-01

    A wide range of pharmacological properties are ascribed to natural saponins, in addition to their biological activities against herbivores, plant soil-borne pathogens and pests. As for animal cells, the cytotoxicity and the chemopreventive role of saponins are mediated by a complex network of signal transduction pathways which include reactive oxygen species (ROS) and nitric oxide (NO). The involvement of other relevant components of the saponin-related signaling routes, such as the Tumor Necrosis Factor (TNF)α, the interleukin (IL)-6 and the Nuclear Transcription FactorκB (NFκB), has been highlighted in animal cells. By contrast, information concerning the response of plant cells to saponins and the related signal transduction pathways is almost missing. To date, there are only a few common features which link plant and animal cells in their response to saponins, such as the early burst in ROS and NO production and the induction of metallothioneins (MTs), small cysteine-rich, metal-binding proteins. This aspect is discussed in the present paper in view of the recent hypothesis that MTs and NO are part of a novel signal transduction pathway participating in the cell response to oxidative stress. PMID:21673512

  14. The Root-Associated Microbial Community of the World's Highest Growing Vascular Plants.

    Science.gov (United States)

    Angel, Roey; Conrad, Ralf; Dvorsky, Miroslav; Kopecky, Martin; Kotilínek, Milan; Hiiesalu, Inga; Schweingruber, Fritz; Doležal, Jiří

    2016-08-01

    Upward migration of plants to barren subnival areas is occurring worldwide due to raising ambient temperatures and glacial recession. In summer 2012, the presence of six vascular plants, growing in a single patch, was recorded at an unprecedented elevation of 6150 m.a.s.l. close to the summit of Mount Shukule II in the Western Himalayas (Ladakh, India). Whilst showing multiple signs of stress, all plants have managed to establish stable growth and persist for several years. To learn about the role of microbes in the process of plant upward migration, we analysed the root-associated microbial community of the plants (three individuals from each) using microscopy and tagged amplicon sequencing. No mycorrhizae were found on the roots, implying they are of little importance to the establishment and early growth of the plants. However, all roots were associated with a complex bacterial community, with richness and diversity estimates similar or even higher than the surrounding bare soil. Both soil and root-associated communities were dominated by members of the orders Sphingomonadales and Sphingobacteriales, which are typical for hot desert soils, but were different from communities of temperate subnival soils and typical rhizosphere communities. Despite taxonomic similarity on the order level, the plants harboured a unique set of highly dominant operational taxonomic units which were not found in the bare soil. These bacteria have been likely transported with the dispersing seeds and became part of the root-associated community following germination. The results indicate that developing soils act not only as a source of inoculation to plant roots but also possibly as a sink for plant-associated bacteria.

  15. Experimental restoration of a fen plant community after peat mining

    Energy Technology Data Exchange (ETDEWEB)

    Cobbaert, D.; Rochefort, L.; Price, J.S. [Univ. Laval, Sainte-Foy (Canada). Dept. de Phytologie

    2004-11-01

    Methods: The effectiveness of introducing fen plants with the application of donor diaspore material was tested. The donor diaspore material, containing seeds, rhizomes, moss fragments, and other plant propagules, was collected from two different types of natural fens. We tested whether the application of straw mulch would increase fen species cover and biodiversity compared to control plots without straw mulch. Terrace levels of different peat depths (15 cm, 40 cm, and 56 cm) were created to test the effects of different environmental site conditions on the success of re-vegetation. Results: Applying donor seed bank from natural fens was found to significantly increase fen plant cover and richness after the two growing seasons. Straw mulch proved to significantly increase fen plant richness. The intermediate terrace level (40 cm) had the highest fen plant establishment. Compared to reference sites, the low terrace level (15 cm) was richer in base cations, whereas the high terrace level (56 cm) was much drier. Conclusions: The application of donor diaspore material was demonstrated as an effective technique for establishing vascular fen plants. Further rewetting measures are considered necessary at the restoration site to create a fen ecosystem rather than simply restoring some fen species (Location: Riviere-du-Loup peatland, southern Quebec, Canada at 100 m a.s.l.)

  16. Indigenous knowledge of medicinal plants used by Saperas community of Khetawas, Jhajjar District, Haryana, India

    Directory of Open Access Journals (Sweden)

    Kumar Sunil

    2010-01-01

    Full Text Available Abstract Background Plants have traditionally been used as a source of medicine in India by indigenous people of different ethnic groups inhabiting various terrains for the control of various ailments afflicting human and their domestic animals. The indigenous community of snake charmers belongs to the 'Nath' community in India have played important role of healers in treating snake bite victims. Snake charmers also sell herbal remedies for common ailments. In the present paper an attempt has been made to document on ethno botanical survey and traditional medicines used by snake charmers of village Khetawas located in district Jhajjar of Haryana, India as the little work has been made in the past to document the knowledge from this community. Methods Ethno botanical data and traditional uses of plants information was obtained by semi structured oral interviews from experienced rural folk, traditional herbal medicine practitioners of the 'Nath' community. A total of 42 selected inhabitants were interviewed, 41 were male and only one woman. The age of the healers was between 25 years and 75 years. The plant specimens were identified according to different references concerning the medicinal plants of Haryana and adjoining areas and further confirmation from Forest Research Institute, Dehradun. Results The present study revealed that the people of the snake charmer community used 57 medicinal plants species that belonged to 51 genera and 35 families for the treatment of various diseases. The study has brought to light that the main diseases treated by this community was snakebite in which 19 different types of medicinal plants belongs to 13 families were used. Significantly higher number of medicinal plants was claimed by men as compared to women. The highest numbers of medicinal plants for traditional uses utilized by this community were belonging to family Fabaceae. Conclusion This community carries a vast knowledge of medicinal plants but as

  17. Invasion of Opuntia humifusa and O. phaeacantha (Cactaceae into plant communities of the Karadag Nature Reserve

    Directory of Open Access Journals (Sweden)

    Valentina V. Fateryga

    2017-11-01

    Full Text Available The results of a study of Opuntia humifusa and O. phaeacantha naturalised in the Karadag Nature Reserve (southeastern part of the Crimean Peninsula are presented. There, the largest coenopopulations of Opuntia plants are confined to the «biostation» territory (bordering with the park, administrative buildings and housing estate. Twelve localities were described in the Karadag Reserve. These differ by phytocoenotic characteristics, area and floristic composition. Seven localities include only O. humifusa plants; four ones include only O. phaeacantha individuals; and both the species are present on the twelfth locality. The total number of individuals of each species and ontogenetic structure of the population were studied in each locality. The total number of O. humifusa individuals in the Karadag Reserve is more than 600 plants within the «biostation» territory, while the total number of O. phaeacantha plants is about 400 individuals. Studying of the plant communities has been carried out according to the Braun-Blanquet method. Opuntia plants form derivate communities within degraded steppes, phryganoid-steppes, and semi-desert badland phytocoenoses almost at all studied localities. A significant number of synanthropic species (including alien plants was found within these communities. Opuntia plants are able to self-reproduce predominantly vegetatively. Self-seeding reproduction occurs less frequently. Both species can be considered as invasive plants because they have a high adaptive capacity.

  18. Neonicotinoid insecticides induce salicylate-associated plant defense responses

    Science.gov (United States)

    Ford, Kevin A.; Casida, John E.; Chandran, Divya; Gulevich, Alexander G.; Okrent, Rachel A.; Durkin, Kathleen A.; Sarpong, Richmond; Bunnelle, Eric M.; Wildermuth, Mary C.

    2010-01-01

    Neonicotinoid insecticides control crop pests based on their action as agonists at the insect nicotinic acetylcholine receptor, which accepts chloropyridinyl- and chlorothiazolyl-analogs almost equally well. In some cases, these compounds have also been reported to enhance plant vigor and (a)biotic stress tolerance, independent of their insecticidal function. However, this mode of action has not been defined. Using Arabidopsis thaliana, we show that the neonicotinoid compounds, imidacloprid (IMI) and clothianidin (CLO), via their 6-chloropyridinyl-3-carboxylic acid and 2-chlorothiazolyl-5-carboxylic acid metabolites, respectively, induce salicylic acid (SA)-associated plant responses. SA is a phytohormone best known for its role in plant defense against pathogens and as an inducer of systemic acquired resistance; however, it can also modulate abiotic stress responses. These neonicotinoids effect a similar global transcriptional response to that of SA, including genes involved in (a)biotic stress response. Furthermore, similar to SA, IMI and CLO induce systemic acquired resistance, resulting in reduced growth of a powdery mildew pathogen. The action of CLO induces the endogenous synthesis of SA via the SA biosynthetic enzyme ICS1, with ICS1 required for CLO-induced accumulation of SA, expression of the SA marker PR1, and fully enhanced resistance to powdery mildew. In contrast, the action of IMI does not induce endogenous synthesis of SA. Instead, IMI is further bioactivated to 6-chloro-2-hydroxypyridinyl-3-carboxylic acid, which is shown here to be a potent inducer of PR1 and inhibitor of SA-sensitive enzymes. Thus, via different mechanisms, these chloropyridinyl- and chlorothiazolyl-neonicotinoids induce SA responses associated with enhanced stress tolerance. PMID:20876120

  19. Plants of the fynbos biome harbour host species-specific bacterial communities.

    Science.gov (United States)

    Miyambo, Tsakani; Makhalanyane, Thulani P; Cowan, Don A; Valverde, Angel

    2016-08-01

    The fynbos biome in South Africa is globally recognised as a plant biodiversity hotspot. However, very little is known about the bacterial communities associated with fynbos plants, despite interactions between primary producers and bacteria having an impact on the physiology of both partners and shaping ecosystem diversity. This study reports on the structure, phylogenetic composition and potential roles of the endophytic bacterial communities located in the stems of three fynbos plants (Erepsia anceps, Phaenocoma prolifera and Leucadendron laureolum). Using Illumina MiSeq 16S rRNA sequencing we found that different subpopulations of Deinococcus-Thermus, Alphaproteobacteria, Acidobacteria and Firmicutes dominated the endophytic bacterial communities. Alphaproteobacteria and Actinobacteria were prevalent in P. prolifera, whereas Deinococcus-Thermus dominated in L. laureolum, revealing species-specific host-bacteria associations. Although a high degree of variability in the endophytic bacterial communities within hosts was observed, we also detected a core microbiome across the stems of the three plant species, which accounted for 72% of the sequences. Altogether, it seems that both deterministic and stochastic processes shaped microbial communities. Endophytic bacterial communities harboured putative plant growth-promoting bacteria, thus having the potential to influence host health and growth. © FEMS 2016. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

  20. Forest understory plant and soil microbial response to an experimentally induced drought and heat-pulse event: the importance of maintaining the continuum

    Science.gov (United States)

    Isabell von Rein; Arthur Gessler; Katrin Premke; Claudia Keitel; Andreas Ulrich; Zachary E. Kayler

    2016-01-01

    Drought duration and intensity are expected to increase with global climate change. How changes in water availability and temperature affect the combined plant–soil–microorganism response remains uncertain. We excavated soil monoliths from a beech (Fagus sylvatica L.) forest, thus keeping the understory plant–microbe communities intact, imposed an...

  1. Responses of bacterial community structure and denitrifying bacteria in biofilm to submerged macrophytes and nitrate

    Science.gov (United States)

    Zhang, Songhe; Pang, Si; Wang, Peifang; Wang, Chao; Guo, Chuan; Addo, Felix Gyawu; Li, Yi

    2016-10-01

    Submerged macrophytes play important roles in constructed wetlands and natural water bodies, as these organisms remove nutrients and provide large surfaces for biofilms, which are beneficial for nitrogen removal, particularly from submerged macrophyte-dominated water columns. However, information on the responses of biofilms to submerged macrophytes and nitrogen molecules is limited. In the present study, bacterial community structure and denitrifiers were investigated in biofilms on the leaves of four submerged macrophytes and artificial plants exposed to two nitrate concentrations. The biofilm cells were evenly distributed on artificial plants but appeared in microcolonies on the surfaces of submerged macrophytes. Proteobacteria was the most abundant phylum in all samples, accounting for 27.3-64.8% of the high-quality bacterial reads, followed by Chloroflexi (3.7-25.4%), Firmicutes (3.0-20.1%), Acidobacteria (2.7-15.7%), Actinobacteria (2.2-8.7%), Bacteroidetes (0.5-9.7%), and Verrucomicrobia (2.4-5.2%). Cluster analysis showed that bacterial community structure can be significantly different on macrophytes versus from those on artificial plants. Redundancy analysis showed that electrical conductivity and nitrate concentration were positively correlated with Shannon index and operational taxonomic unit (OTU) richness (log10 transformed) but somewhat negatively correlated with microbial density. The relative abundances of five denitrifying genes were positively correlated with nitrate concentration and electrical conductivity but negatively correlated with dissolved oxygen.

  2. The community response to aircraft noise around six Spanish airports

    Science.gov (United States)

    Garcia, A.; Faus, L. J.; Garcia, A. M.

    1993-06-01

    The community response to aircraft noise has been studied through a social survey. A total of 1800 persons living in the vicinity of six major Spanish airports have been interviewed at their homes concerning the environmental quality of the area, dissatisfaction with road traffic noise and aircraft noise, activities interfered with by noise, most disturbing aircraft types, and subjective evaluation of airport impact. All the responses obtained in this survey have been compared with aircraft noise levels corresponding to the residence locations of the people interviewed (values of NEF levels were calculated with the INM model). The results obtained in this work allow one to evaluate the impact of aircraft noise under a wide range of different situations.

  3. Granivory of invasive, naturalized, and native plants in communities differentially susceptible to invasion.

    Science.gov (United States)

    Connolly, B M; Pearson, D E; Mack, R N

    2014-07-01

    Seed predation is an important biotic filter that can influence abundance and spatial distributions of native species through differential effects on recruitment. This filter may also influence the relative abundance of nonnative plants within habitats and the communities' susceptibility to invasion via differences in granivore identity, abundance, and food preference. We evaluated the effect of postdispersal seed predators on the establishment of invasive, naturalized, and native species within and between adjacent forest and steppe communities of eastern Washington, USA that differ in severity of plant invasion. Seed removal from trays placed within guild-specific exclosures revealed that small mammals were the dominant seed predators in both forest and steppe. Seeds of invasive species (Bromus tectorum, Cirsium arvense) were removed significantly less than the seeds of native (Pseudoroegneria spicata, Balsamorhiza sagittata) and naturalized (Secale cereale, Centaurea cyanus) species. Seed predation limited seedling emergence and establishment in both communities in the absence of competition in a pattern reflecting natural plant abundance: S. cereale was most suppressed, B. tectorum was least suppressed, and P. spicata was suppressed at an intermediate level. Furthermore, seed predation reduced the residual seed bank for all species. Seed mass correlated with seed removal rates in the forest and their subsequent effects on plant recruitment; larger seeds were removed at higher rates than smaller seeds. Our vegetation surveys indicate higher densities and canopy cover of nonnative species occur in the steppe compared with the forest understory, suggesting the steppe may be more susceptible to invasion. Seed predation alone, however, did not result in significant differences in establishment for any species between these communities, presumably due to similar total small-mammal abundance between communities. Consequently, preferential seed predation by small

  4. Lineage-specific responses of microbial communities to environmental change.

    Science.gov (United States)

    Youngblut, Nicholas D; Shade, Ashley; Read, Jordan S; McMahon, Katherine D; Whitaker, Rachel J

    2013-01-01

    A great challenge facing microbial ecology is how to define ecologically relevant taxonomic units. To address this challenge, we investigated how changing the definition of operational taxonomic units (OTUs) influences the perception of ecological patterns in microbial communities as they respond to a dramatic environmental change. We used pyrosequenced tags of the bacterial V2 16S rRNA region, as well as clone libraries constructed from the cytochrome oxidase C gene ccoN, to provide additional taxonomic resolution for the common freshwater genus Polynucleobacter. At the most highly resolved taxonomic scale, we show that distinct genotypes associated with the abundant Polynucleobacter lineages exhibit divergent spatial patterns and dramatic changes over time, while the also abundant Actinobacteria OTUs are highly coherent. This clearly demonstrates that different bacterial lineages demand different taxonomic definitions to capture ecological patterns. Based on the temporal distribution of highly resolved taxa in the hypolimnion, we demonstrate that change in the population structure of a single genotype can provide additional insight into the mechanisms of community-level responses. These results highlight the importance and feasibility of examining ecological change in microbial communities across taxonomic scales while also providing valuable insight into the ecological characteristics of ecologically coherent groups in this system.

  5. Advances in modeling trait-based plant community assembly.

    Science.gov (United States)

    Laughlin, Daniel C; Laughlin, David E

    2013-10-01

    In this review, we examine two new trait-based models of community assembly that predict the relative abundance of species from a regional species pool. The models use fundamentally different mathematical approaches and the predictions can differ considerably. Maxent obtains the most even probability distribution subject to community-weighted mean trait constraints. Traitspace predicts low probabilities for any species whose trait distribution does not pass through the environmental filter. Neither model maximizes functional diversity because of the emphasis on environmental filtering over limiting similarity. Traitspace can test for the effects of limiting similarity by explicitly incorporating intraspecific trait variation. The range of solutions in both models could be used to define the range of natural variability of community composition in restoration projects. Copyright © 2013 Elsevier Ltd. All rights reserved.

  6. Stubble field plant communities of the Mazowiecki Landscape Park

    Directory of Open Access Journals (Sweden)

    Teresa Skrajna

    2012-12-01

    Full Text Available The characteristics of communities found in unploughed stubble fields of the Mazowiecki Landscape Park and its agricultural buffer zone are presented in the paper. The association Echinochloo-Setarietum divided into a typical variant, the variant with Galinsoga parviflora, and the variant with Bidens tripartite, was the most frequently noted and floristically differentiated association. Patches of Digitarietum ischaemi were also frequently observed in stubble fields on the poorest habitats. Rarely, on fertile soils, small patches of floristically rich communities with Veronica agrestis were recorded. Periodically, excessively wet habitats were seldom occupied by the speciesrichest phytocoenoses of Centunculo-Anthoceretum punctati. Single patches of the community with Setaria pumila, the form with Aphanes arvensis, were observed only in the south-eastern part of the Park.

  7. Transcriptional responses of Arabidopsis thaliana plants to As (V stress

    Directory of Open Access Journals (Sweden)

    Yuan Joshua S

    2008-08-01

    Full Text Available Abstract Background Arsenic is toxic to plants and a common environmental pollutant. There is a strong chemical similarity between arsenate [As (V] and phosphate (Pi. Whole genome oligonucleotide microarrays were employed to investigate the transcriptional responses of Arabidopsis thaliana plants to As (V stress. Results Antioxidant-related genes (i.e. coding for superoxide dismutases and peroxidases play prominent roles in response to arsenate. The microarray experiment revealed induction of chloroplast Cu/Zn superoxide dismutase (SOD (at2g28190, Cu/Zn SOD (at1g08830, as well as an SOD copper chaperone (at1g12520. On the other hand, Fe SODs were strongly repressed in response to As (V stress. Non-parametric rank product statistics were used to detect differentially expressed genes. Arsenate stress resulted in the repression of numerous genes known to be induced by phosphate starvation. These observations were confirmed with qRT-PCR and SOD activity assays. Conclusion Microarray data suggest that As (V induces genes involved in response to oxidative stress and represses transcription of genes induced by phosphate starvation. This study implicates As (V as a phosphate mimic in the cell by repressing genes normally induced when available phosphate is scarce. Most importantly, these data reveal that arsenate stress affects the expression of several genes with little or unknown biological functions, thereby providing new putative gene targets for future research.

  8. Rhizosphere microbial community structure in relation to root location and plant iron nutritional status.

    Science.gov (United States)

    Yang, C H; Crowley, D E

    2000-01-01

    Root exudate composition and quantity vary in relation to plant nutritional status, but the impact of the differences on rhizosphere microbial communities is not known. To examine this question, we performed an experiment with barley (Hordeum vulgare) plants under iron-limiting and iron-sufficient growth conditions. Plants were grown in an iron-limiting soil in root box microcosms. One-half of the plants were treated with foliar iron every day to inhibit phytosiderophore production and to alter root exudate composition. After 30 days, the bacterial communities associated with different root zones, including the primary root tips, nonelongating secondary root tips, sites of lateral root emergence, and older roots distal from the tip, were characterized by using 16S ribosomal DNA (rDNA) fingerprints generated by PCR-denaturing gradient gel electrophoresis (DGGE). Our results showed that the microbial communities associated with the different root locations produced many common 16S rDNA bands but that the communities could be distinguished by using correspondence analysis. Approximately 40% of the variation between communities could be attributed to plant iron nutritional status. A sequence analysis of clones generated from a single 16S rDNA band obtained at all of the root locations revealed that there were taxonomically different species in the same band, suggesting that the resolving power of DGGE for characterization of community structure at the species level is limited. Our results suggest that the bacterial communities in the rhizosphere are substantially different in different root zones and that a rhizosphere community may be altered by changes in root exudate composition caused by changes in plant iron nutritional status.

  9. Effects of water table position and plant functional group on plant community, aboveground production, and peat properties in a peatland mesocosm experiment (PEATcosm)

    Science.gov (United States)

    Lynette R. Potvin; Evan S. Kane; Rodney A. Chimner; Randall K. Kolka; Erik A. Lilleskov

    2015-01-01

    Aims Our objective was to assess the impacts of water table position and plant functional type on peat structure, plant community composition and aboveground plant production. Methods We initiated a full factorial experiment with 2 water table (WT) treatments (high and low) and 3 plant functional groups (PFG: sedge, Ericaceae,...

  10. Community Visions for the Paducah Gaseous Diffusion Plant Site

    Energy Technology Data Exchange (ETDEWEB)

    Ormsbee, Lindell e [Civil Engineering, Univ. of KY; Kipp, James A [Univ. of KY, Kentucky water research Institute

    2011-09-01

    This report focuses on assessing community preferences for the future use of the PGDP site, given the site's pending closure by US DOE. The project approach fostered interaction and engagement with the public based on lessons learned at other complex DOE environmental cleanup sites and upon the integration of a number of principles and approaches to public engagement from the Project Team's local, state, regional and international public engagement experience. The results of the study provide the community with a record of the diversity of values and preferences related to the environmental cleanup and future use of the site.

  11. Bacterial community structure and diversity responses to the direct revegetation of an artisanal zinc smelting slag after 5 years.

    Science.gov (United States)

    Luo, Youfa; Wu, Yonggui; Wang, Hu; Xing, Rongrong; Zheng, Zhilin; Qiu, Jing; Yang, Lian

    2018-05-01

    This comparative field study examined the responses of bacterial community structure and diversity to the revegetation of zinc (Zn) smelting waste slag with eight plant species after 5 years. The microbial community structure of waste slag with and without vegetation was evaluated using high-throughput sequencing. The physiochemical properties of Zn smelting slag after revegetation with eight plant rhizospheres for 5 years were improved compared to those of bulk slag. Revegetation significantly increased the microbial community diversity in plant rhizospheres, and at the phylum level, Proteobacteria, Acidobacteria, and Bacteroidetes were notably more abundant in rhizosphere slags than those in bulk waste slag. Additionally, revegetation increased the relative abundance of plant growth-promoting rhizobacteria such as Flavobacterium, Streptomyces, and Arthrobacter as well as symbiotic N 2 fixers such as Bradyrhizobium. Three dominant native plant species (Arundo donax, Broussonetia papyrifera, and Robinia pseudoacacia) greatly increased the quality of the rhizosphere slags. Canonical correspondence analysis showed that the differences in bacterial community structure between the bulk and rhizosphere slags were explained by slag properties, i.e., pH, available copper (Cu) and lead (Pb), moisture, available nitrogen (N), phosphorus (P), and potassium (K), and organic matter (OM); however, available Zn and cadmium (Cd) contents were the slag parameters that best explained the differences between the rhizosphere communities of the eight plant species. The results suggested that revegetation plays an important role in enhancing bacterial community abundance and diversity in rhizosphere slags and that revegetation may also regulate microbiological properties and diversity mainly through changes in heavy metal bioavailability and physiochemical slag characteristics.

  12. Litter drives ecosystem and plant community changes in cattail invasion.

    Science.gov (United States)

    Farrer, Emily C; Goldberg, Deborah E

    2009-03-01

    Invaded systems are commonly associated with a change in ecosystem processes and a decline in native species diversity; however, many different causal pathways linking invasion, ecosystem change, and native species decline could produce this pattern. The initial driver of environmental change may be anthropogenic, or it may be the invader itself; and the mechanism behind native species decline may be the human-induced environmental change, competition from the invader, or invader-induced environmental change (non-trophic effects). We examined applicability of each of these alternate pathways in Great Lakes coastal marshes invaded by hybrid cattail (Typha x glauca). In a survey including transects in three marshes, we found that T. x glauca was associated with locally high soil nutrients, low light, and large amounts of litter, and that native diversity was highest in areas of shallow litter depth. We tested whether live T. x glauca plants or their litter induced changes in the environment and in diversity with a live plant and litter transplant experiment. After one year, Typha litter increased soil NH4+ and N mineralization twofold, lowered light levels, and decreased the abundance and diversity of native plants, while live Typha plants had no effect on the environment or on native plants. This suggests that T. x glauca, through its litter production, can cause the changes in ecosystem processes that we commonly attribute to anthropogenic nutrient loading and that T. x glauca does not displace native species through competition for resources, but rather affects them non-trophically through its litter. Moreover, because T. x glauca plants were taller when grown with their own litter, we suggest that this invader may produce positive feedbacks and change the environment in ways that benefit itself and may promote its own invasion.

  13. The Importance of Biotic vs. Abiotic Drivers of Local Plant Community Composition Along Regional Bioclimatic Gradients.

    Directory of Open Access Journals (Sweden)

    Kari Klanderud

    Full Text Available We assessed if the relative importance of biotic and abiotic factors for plant community composition differs along environmental gradients and between functional groups, and asked which implications this may have in a warmer and wetter future. The study location is a unique grid of sites spanning regional-scale temperature and precipitation gradients in boreal and alpine grasslands in southern Norway. Within each site we sampled vegetation and associated biotic and abiotic factors, and combined broad- and fine-scale ordination analyses to assess the relative explanatory power of these factors for species composition. Although the community responses to biotic and abiotic factors did not consistently change as predicted along the bioclimatic gradients, abiotic variables tended to explain a larger proportion of the variation in species composition towards colder sites, whereas biotic variables explained more towards warmer sites, supporting the stress gradient hypothesis. Significant interactions with precipitation suggest that biotic variables explained more towards wetter climates in the sub alpine and boreal sites, but more towards drier climates in the colder alpine. Thus, we predict that biotic interactions may become more important in alpine and boreal grasslands in a warmer future, although more winter precipitation may counteract this trend in oceanic alpine climates. Our results show that both local and regional scales analyses are needed to disentangle the local vegetation-environment relationships and their regional-scale drivers, and biotic interactions and precipitation must be included when predicting future species assemblages.

  14. Fate of polycyclic aromatic hydrocarbons in plant-soil systems: Plant responses to a chemical stress in the root zone

    Energy Technology Data Exchange (ETDEWEB)

    Hoylman, Anne M. [Univ. of Tennessee, Knoxville, TN (United States)

    1994-01-01

    Under laboratory conditions selected to maximize root uptake, plant tissue distribution of PAH-derived 14C was largely limited to root tissue of Malilotus alba. These results suggest that plant uptake of PAHs from contaminated soil via roots, and translocation to aboveground plant tissues (stems and leaves), is a limited mechanism for transport into terrestrial food chains. However, these data also indicate that root surface sorption of PAHs may be important for plants grown in soils containing elevated concentration PAHs. Root surface sorption of PAHs may be an important route of exposure for plants in soils containing elevated concentrations of PAHS. Consequently, the root-soil interface may be the site of plant-microbial interactions in response to a chemical stress. In this study, evidence of a shift in carbon allocation to the root zone of plants exposed to phenanthrene and corresponding increases in soil respiration and heterotrophic plate counts provide evidence of a plant-microbial response to a chemical stress. The results of this study establish the importance of the root-soil interface for plants growing in PAH contaminated soil and indicate the existence of plant-microbial interactions in response to a chemical stress. These results may provide new avenues of inquiry for studies of plant toxicology, plant-microbial interactions in the rhizosphere, and environmental fates of soil contaminants. In addition, the utilization of plants to enhance the biodegradation of soil contaminants may require evaluation of plant physiological changes and plant shifts in resource allocation.

  15. Simulation of plant communities with a cellular automaton

    Energy Technology Data Exchange (ETDEWEB)

    Gassmann, F [Paul Scherrer Inst. (PSI), Villigen (Switzerland)

    1999-08-01

    With a modelling approach based on cellular automata, five observed types of plant development can be simulated. In addition, the proposed model shows a strong tendency towards the formation of patches and a high degree of dynamical and structural instability leading to limits of predictability for the asymptotic solution chosen by the system among several possible metastable patterns (multistability). Further, external fluctuations can be shown to have advantages for certain plant types. The presented model unifies the fundamental dichotomy in vegetation dynamics between determinism (understood as predictability) and disorder (chance effects) by showing the outcome of both classical theories as special cases. (author) 2 figs., 4 refs.

  16. Life form succession in plant communities on colliery waste tips

    Energy Technology Data Exchange (ETDEWEB)

    Down, C G

    1973-01-01

    Five disused colliery waste tips in the Somerset Coalfield, 12, 15, 21, 55 and 98 years old, respectively, were examined to determine the life forms of the naturally-occurring vascular plant species. Hemicryptophytes comprised between 68 and 79% of the number of species on each tip. Rosette hemicryptophytes comprised 31.8% of the species on the 12-year tip, declining to 11.8% on the 98-year tip. It is suggested that artificial planting of rosette hemicryptophytes may be beneficial in reclamation schemes. 3 tables.

  17. Contrasting growth responses of dominant peatland plants to warming and vegetation composition.

    Science.gov (United States)

    Walker, Tom N; Ward, Susan E; Ostle, Nicholas J; Bardgett, Richard D

    2015-05-01

    There is growing recognition that changes in vegetation composition can strongly influence peatland carbon cycling, with potential feedbacks to future climate. Nevertheless, despite accelerated climate and vegetation change in this ecosystem, the growth responses of peatland plant species to combined warming and vegetation change are unknown. Here, we used a field warming and vegetation removal experiment to test the hypothesis that dominant species from the three plant functional types present (dwarf-shrubs: Calluna vulgaris; graminoids: Eriophorum vaginatum; bryophytes: Sphagnum capillifolium) contrast in their growth responses to warming and the presence or absence of other plant functional types. Warming was accomplished using open top chambers, which raised air temperature by approximately 0.35 °C, and we measured air and soil microclimate as potential mechanisms through which both experimental factors could influence growth. We found that only Calluna growth increased with experimental warming (by 20%), whereas the presence of dwarf-shrubs and bryophytes increased growth of Sphagnum (46%) and Eriophorum (20%), respectively. Sphagnum growth was also negatively related to soil temperature, which was lower when dwarf-shrubs were present. Dwarf-shrubs may therefore promote Sphagnum growth by cooling the peat surface. Conversely, the effect of bryophyte presence on Eriophorum growth was not related to any change in microclimate, suggesting other factors play a role. In conclusion, our findings reveal contrasting abiotic and biotic controls over dominant peatland plant growth, suggesting that community composition and carbon cycling could be modified by simultaneous climate and vegetation change.

  18. Effects of silver sulfide nanomaterials on mycorrhizal colonization of tomato plants and soil microbial communities in biosolid-amended soil

    International Nuclear Information System (INIS)

    Judy, Jonathan D.; Kirby, Jason K.; Creamer, Courtney; McLaughlin, Mike J.; Fiebiger, Cathy; Wright, Claire; Cavagnaro, Timothy R.; Bertsch, Paul M.

    2015-01-01

    We investigated effects of Ag_2S engineered nanomaterials (ENMs), polyvinylpyrrolidone (PVP) coated Ag ENMs (PVP-Ag), and Ag"+ on arbuscular mycorrhizal fungi (AMF), their colonization of tomato (Solanum lycopersicum), and overall microbial community structure in biosolids-amended soil. Concentration-dependent uptake was measured in all treatments. Plants exposed to 100 mg kg"−"1 PVP-Ag ENMs and 100 mg kg"−"1 Ag"+ exhibited reduced biomass and greatly reduced mycorrhizal colonization. Bacteria, actinomycetes and fungi were inhibited by all treatment classes, with the largest reductions measured in 100 mg kg"−"1 PVP-Ag ENMs and 100 mg kg"−"1 Ag"+. Overall, Ag_2S ENMs were less toxic to plants, less disruptive to plant-mycorrhizal symbiosis, and less inhibitory to the soil microbial community than PVP-Ag ENMs or Ag"+. However, significant effects were observed at 1 mg kg"−"1 Ag_2S ENMs, suggesting that the potential exists for microbial communities and the ecosystem services they provide to be disrupted by environmentally relevant concentrations of Ag_2S ENMs. - Highlights: • PVP-Ag and Ag"+ inhibited AMF colonization more readily than Ag_2S ENMs. • Impact of PVP-Ag ENMs and Ag"+ on microbial communities larger than for Ag_2S ENMs. • Significant changes in microbial communities in response to Ag_2S ENMs at 1 mg kg"−"1. - Although Ag_2S ENMs are less toxic to soil microorganisms than pristine nanomaterials or ions, some effects are observed on soil microbial communities at relevant concentrations.

  19. [Soil catalase activity of main plant communities in Leymus chinensis grassland in northeast China].

    Science.gov (United States)

    Lu, Ping; Guo, Jixun; Zhu, Li

    2002-06-01

    The seasonal dynamics of soil catalase activity of three different plants communities in Leymus chinensis grassland in northeast China were in a parabolas shape. The seasonal variation of Chloris virgata community was greater than those of Leymus chinensis community and Puccinellia tenuiflora community, and "seed effect" might be the main reason. The correlation between the activity of soil catalase in different soil layers and environmental factors were analyzed. The results showed that the activity of soil catalase was decreased gradually with depth of soil layer. The activity of soil catalase was closely correlated with rainfall and air temperature, and it was affected by soil temperature, soil moisture, and their interactions. The correlation between the activity and aboveground vegetation was very significant, and the growing condition of plant communities could be reflected by the activity of soil catalase.

  20. Soil microbial community responses to acid exposure and neutralization treatment.

    Science.gov (United States)

    Shin, Doyun; Lee, Yunho; Park, Jeonghyun; Moon, Hee Sun; Hyun, Sung Pil

    2017-12-15

    Changes in microbial community induced by acid shock were studied in the context of potential release of acids to the environment due to chemical accidents. The responses of microbial communities in three different soils to the exposure to sulfuric or hydrofluoric acid and to the subsequent neutralization treatment were investigated as functions of acid concentration and exposure time by using 16S-rRNA gene based pyrosequencing and DGGE (Denaturing Gradient Gel Electrophoresis). Measurements of soil pH and dissolved ion concentrations revealed that the added acids were neutralized to different degrees, depending on the mineral composition and soil texture. Hydrofluoric acid was more effectively neutralized by the soils, compared with sulfuric acid at the same normality. Gram-negative ß-Proteobacteria were shown to be the most acid-sensitive bacterial strains, while spore-forming Gram-positive Bacilli were the most acid-tolerant. The results of this study suggest that the Gram-positive to Gram-negative bacterial ratio may serve as an effective bio-indicator in assessing the impact of the acid shock on the microbial community. Neutralization treatments helped recover the ratio closer to their original values. The findings of this study show that microbial community changes as well as geochemical changes such as pH and dissolved ion concentrations need to be considered in estimating the impact of an acid spill, in selecting an optimal remediation strategy, and in deciding when to end remedial actions at the acid spill impacted site. Copyright © 2017 Elsevier Ltd. All rights reserved.

  1. Avian community responses to variability in river hydrology.

    Science.gov (United States)

    Royan, Alexander; Hannah, David M; Reynolds, S James; Noble, David G; Sadler, Jonathan P

    2013-01-01

    River flow is a major driver of morphological structure and community dynamics in riverine-floodplain ecosystems. Flow influences in-stream communities through changes in water velocity, depth, temperature, turbidity and nutrient fluxes, and perturbations in the organisation of lower trophic levels are cascaded through the food web, resulting in shifts in food availability for consumer species. River birds are sensitive to spatial and phenological mismatches with aquatic prey following flow disturbances; however, the role of flow as a determinant of riparian ecological structure remains poorly known. This knowledge is crucial to help to predict if, and how, riparian communities will be influenced by climate-induced changes in river flow characterised by more extreme high (i.e. flood) and/or low (i.e. drought) flow events. Here, we combine national-scale datasets of river bird surveys and river flow archives to understand how hydrological disturbance has affected the distribution of riparian species at higher trophic levels. Data were analysed for 71 river locations using a Generalized Additive Model framework and a model averaging procedure. Species had complex but biologically interpretable associations with hydrological indices, with species' responses consistent with their ecology, indicating that hydrological-disturbance has implications for higher trophic levels in riparian food webs. Our quantitative analysis of river flow-bird relationships demonstrates the potential vulnerability of riparian species to the impacts of changing flow variability and represents an important contribution in helping to understand how bird communities might respond to a climate change-induced increase in the intensity of floods and droughts. Moreover, the success in relating parameters of river flow variability to species' distributions highlights the need to include river flow data in climate change impact models of species' distributions.

  2. Plant natriuretic peptides are apoplastic and paracrine stress response molecules

    KAUST Repository

    Wang, Yuhua

    2011-04-07

    Higher plants contain biologically active proteins that are recognized by antibodies against human atrial natriuretic peptide (ANP). We identified and isolated two Arabidopsis thaliana immunoreactive plant natriuretic peptide (PNP)-encoding genes, AtPNP-A and AtPNP-B, which are distantly related members of the expansin superfamily and have a role in the regulation of homeostasis in abiotic and biotic stresses, and have shown that AtPNP-A modulates the effects of ABA on stomata. Arabidopsis PNP (PNP-A) is mainly expressed in leaf mesophyll cells, and in protoplast assays we demonstrate that it is secreted using AtPNP-A:green fluorescent protein (GFP) reporter constructs and flow cytometry. Transient reporter assays provide evidence that AtPNP-A expression is enhanced by heat, osmotica and salt, and that AtPNP-A itself can enhance its own expression, thereby generating a response signature diagnostic for paracrine action and potentially also autocrine effects. Expression of native AtPNP-A is enhanced by osmotica and transiently by salt. Although AtPNP-A expression is induced by salt and osmotica, ABA does not significantly modulate AtPNP-A levels nor does recombinant AtPNP-A affect reporter expression of the ABA-responsive RD29A gene. Together, these results provide experimental evidence that AtPNP-A is stress responsive, secreted into the apoplastic space and can enhance its own expression. Furthermore, our findings support the idea that AtPNP-A, together with ABA, is an important component in complex plant stress responses and that, much like in animals, peptide signaling molecules can create diverse and modular signals essential for growth, development and defense under rapidly changing environmental conditions. © 2011 The Author.

  3. Herboxidiene triggers splicing repression and abiotic stress responses in plants

    KAUST Repository

    Alshareef, Sahar

    2017-03-27

    Background Constitutive and alternative splicing of pre-mRNAs from multiexonic genes controls the diversity of the proteome; these precisely regulated processes also fine-tune responses to cues related to growth, development, and stresses. Small-molecule inhibitors that perturb splicing provide invaluable tools for use as chemical probes to uncover the molecular underpinnings of splicing regulation and as potential anticancer compounds. Results Here, we show that herboxidiene (GEX1A) inhibits both constitutive and alternative splicing. Moreover, GEX1A activates genome-wide transcriptional patterns involved in abiotic stress responses in plants. GEX1A treatment -activated ABA-inducible promoters, and led to stomatal closure. Interestingly, GEX1A and pladienolide B (PB) elicited similar cellular changes, including alterations in the patterns of transcription and splicing, suggesting that these compounds might target the same spliceosome complex in plant cells. Conclusions Our study establishes GEX1A as a potent splicing inhibitor in plants that can be used to probe the assembly, dynamics, and molecular functions of the spliceosome and to study the interplay between splicing stress and abiotic stresses, as well as having potential biotechnological applications.

  4. Plant responses to environmental stresses-from gene to biotechnology.

    Science.gov (United States)

    Ahanger, Mohammad Abass; Akram, Nudrat Aisha; Ashraf, Muhammad; Alyemeni, Mohammed Nasser; Wijaya, Leonard; Ahmad, Parvaiz

    2017-07-01

    Increasing global population, urbanization and industrialization are increasing the rate of conversion of arable land into wasteland. Supplying food to an ever-increasing population is one of the biggest challenges that agriculturalists and plant scientists are currently confronting. Environmental stresses make this situation even graver. Despite the induction of several tolerance mechanisms, sensitive plants often fail to survive under environmental extremes. New technological approaches are imperative. Conventional breeding methods have a limited potential to improve plant genomes against environmental stress. Recently, genetic engineering has contributed enormously to the development of genetically modified varieties of different crops such as cotton, maize, rice, canola and soybean. The identification of stress-responsive genes and their subsequent introgression or overexpression within sensitive crop species are now being widely carried out by plant scientists. Engineering of important tolerance pathways, like antioxidant enzymes, osmolyte accumulation, membrane-localized transporters for efficient compartmentation of deleterious ions and accumulation of essential elements and resistance against pests or pathogens is also an area that has been intensively researched. In this review, the role of biotechnology and its successes, prospects and challenges in developing stress-tolerant crop cultivars are discussed.

  5. [Relation between species distribution of plant community and soil factors under grazing in alpine meadow].

    Science.gov (United States)

    Niu, Yu Jie; Yang, Si Wei; Wang, Gui Zhen; Liu, Li; Du, Guo Zhen; Hua, Li Min

    2017-12-01

    The research selected the alpine meadow located in the northeastern margin of the Qinghai-Tibet Plateau to study the changes of vegetation community and soil properties under different grazing intensities, as well as the quantitative relation between the distribution patterns of plant species and the physical and chemical properties of soil. The results showed that the grazing caused the differentiation of the initial vegetation community with the dominant plants, Elymus nutans and Stipa grandis. In the plots with high and low grazing intensities, the dominant plants had changed to Kobresia humilis and Melissitus ruthenica, and E. nutans and Poa crymophila, respectively. With the increase of grazing intensity, the plant richness, importance value and biomass were significantly decreased. The sequence of plant species importance value in each plot against grazing intensity could be fitted by a logarithmic model. The number of required plant species was reduced while the importance value of the remaining plant species accounted for 50% of the importance value in the whole vegetation community. The available P, available K, soil compaction, soil water content, stable infiltration rate and large aggregate index were significantly changed with grazing intensity, however, the changes were different. The CCA ordination showed that the soil compaction was the key factor affecting the distribution pattern of the plant species under grazing. The variance decomposition indicated that the soil factors together explained 30.5% of the distribution of the plant species, in particular the soil physical properties alone explained 22.8% of the distribution of the plant species, which had the highest rate of contribution to the plant species distribution. The soil physical properties affected the distribution pattern of plant species on grazed alpine meadow.

  6. Dispersal and life span spectra in plant communities : a key to safe site dynamics, species coexistence and conservation

    NARCIS (Netherlands)

    Strykstra, RJ; Bekker, RM; Van Andel, J

    Dispersal and life span of individual plant species within five plant communities were assessed to obtain a characterization of these communities in this respect. Such a characterization is important in the context of restoration and maintenance. The most frequent species of five communities were

  7. Interior West community tree guide: benefits, costs, and strategic planting

    Science.gov (United States)

    Kelaine E. Vargas; Gregory E. McPherson; James R. Simpson; Paula J. Peper; Shelley L. Gardner; Qingfu. Xiao

    2007-01-01

    Even as they increase the beauty of our surroundings, trees provide us with a great many ecosystem services, including air quality improvement, energy conservation, stormwater interception, and atmospheric carbon dioxide reduction. These benefits must be weighed against the costs of maintaining trees, including planting, pruning, irrigation, administration, pest...

  8. Central Florida community tree guide: benefits, costs, and strategic planting

    Science.gov (United States)

    Paula J. Peper; E. Gregory McPherson; James R. Simpson; Shannon N. Albers; Qingfu Xiao

    2010-01-01

    Trees make our cities more attractive and provide many ecosystem services, including air quality improvement, energy conservation, stormwater interception, and atmospheric carbon dioxide reduction. These benefits must be weighed against the costs of maintaining trees, including planting, pruning, irrigation, administration, pest control, liability, cleanup, and removal...

  9. Desert Southwest Community Tree Guide: Benefits, Costs and Strategic Planting

    Science.gov (United States)

    Greg McPherson; J.R. Simpson; P.J. Peper; S.E. Maco; Q. Xiao; E. Mulrean

    2004-01-01

    This report quantifies benefits and costs for typical large-, medium-, small-stature, deciduous trees (Fraxinus uhdei, Prosopis chilensis, Acacia farnesiana), as well as a conifer (Pinus halapensis). The analysis assumed that trees were planted in a residential yard site or a public (street/park) site, a 40-year time frame, and...

  10. Lower Midwest community tree guide: benefits, costs, and strategic planting

    Science.gov (United States)

    Paula J. Peper; E. Gregory McPherson; James R. Simpson; Kelaine E. Vargas; Qingfu Xiao

    2009-01-01

    Even as they increase the beauty of our surroundings, trees provide us with a great many ecosystem services, including air quality improvement, energy conservation, stormwater interception, and atmospheric carbon dioxide reduction. These benefits must be weighed against the costs of maintaining trees, including planting, pruning, irrigation, administration, pest...

  11. Tropical community tree guide: benefits, costs, and strategic planting

    Science.gov (United States)

    Kelaine E. Vargas; Gregory E. McPherson; James R. Simpson; Paula J. Peper; Shelley L. Gardner; Qingfu Xiao

    2008-01-01

    Even as they increase the beauty of our surroundings, trees provide us with a great many ecosystem services, including air quality improvement, energy conservation, stormwater interception, and atmospheric carbon dioxide reduction. These benefits must be weighed against the costs of maintaining trees, including planting, pruning, irrigation, administration, pest...

  12. Midwest community tree guide: benefits, costs, and strategic planting

    Science.gov (United States)

    E. Gregory McPherson; James R. Simpson; Paula J. Peper; Scott E. Maco; Shelley L. Gardner; Shauna K. Cozad; Qingfu Xiao

    2006-01-01

    This report quantifies benefits and costs for typical small, medium, and large deciduous (losing their leaves every autumn) trees: crabapple, red oak, and hackberry (see "Common and Scientific Names" section). The analysis assumed that trees were planted in a residential yard or public site (streetside or park) with a 60 percent survival rate over a 40-year...

  13. Northeast community tree guide: benefits, costs, and strategic planting

    Science.gov (United States)

    E. Gregory McPherson; James R. Simpson; Paula J. Peper; Shelley L. Gardner; Kelaine E. Vargas; Qingfu Xiao

    2007-01-01

    Trees make our cities more attractive and provide many ecosystem services, including air quality improvement, energy conservation, stormwater interception, and atmospheric carbon dioxide reduction. These benefits must be weighed against the costs of maintaining trees, including planting, pruning, irrigation, administration, pest control, liability, cleanup, and removal...

  14. Validation on wheat response to irrigation, CO2 and nitrogen fertilization in the Community Land Model

    Science.gov (United States)

    Lu, Y.

    2016-12-01

    Wheat is a staple crop for global food security, and is the dominant vegetation cover for a significant fraction of earth's croplands. As such, it plays an important role in soil carbon balance, and land-atmosphere interactions in these key regions. Understanding whether the Community Land Model (CLM) appropriate response to elevated CO2 and different levels of nitrogen fertilization and irrigation is a crucial question. We participated the AgMIP-wheat project and run 72 simulations at Maricopa spring wheat FACE sites and five winter wheat sites in North America forcing with site observed meteorology data. After calibration on the phenology, carbon allocation, and soil hydrology parameters, wheat in CLM45 has reasonable response to irrigation and elevated CO2. However, wheat in CLM45 has no response to low or high N fertilization because the low amount of N fertilization is sufficient for wheat growth in CLM45. We plan to further extend the same simulations for CLM5 (will release in Fall 2016), which has substantial improvements on soil hydrology (improved soil evaporation and plant hydraulic parameterization) and nitrogen dynamics (flexible leaf CN ratio and Vcmax25, plant pays for carbon to get nitrogen). We will evaluate the uncertainties of wheat response to nitrogen fertilization, irrigation, CO2 due to model improvements.

  15. Disease resistance or growth: the role of plant hormones in balancing immune responses and fitness costs

    NARCIS (Netherlands)

    Denance, N.; Sanchez Vallet, A.; Goffner, D.; Molina, A.

    2013-01-01

    Plant growth and response to environmental cues are largely governed by phytohormones. The plant hormones ethylene, jasmonic acid, and salicylic acid (SA) play a central role in the regulation of plant immune responses. In addition, other plant hormones, such as auxins, abscisic acid (ABA),

  16. Crossfit analysis: a novel method to characterize the dynamics of induced plant responses

    NARCIS (Netherlands)

    Jansen, J.J.; Van Dam, N.M.; Hoefsloot, H.C.J.; Smilde, A.K.

    2009-01-01

    Background Many plant species show induced responses that protect them against exogenous attacks. These responses involve the production of many different bioactive compounds. Plant species belonging to the Brassicaceae family produce defensive glucosinolates, which may greatly influence their

  17. Crossfit analysis: a novel method to characterize the dynamics of induced plant responses

    NARCIS (Netherlands)

    Jansen, J.J.; van Dam, N.M.; Hoefsloot, H.C.J.; Smilde, A.K.

    2009-01-01

    Background: Many plant species show induced responses that protect them against exogenous attacks. These responses involve the production of many different bioactive compounds. Plant species belonging to the Brassicaceae family produce defensive glucosinolates, which may greatly influence their

  18. Response of equipment in nuclear power plants to airplane crash

    International Nuclear Information System (INIS)

    Schalk, M.; Woelfel, H.

    1976-01-01

    Nuclear power plants in Germany are to be designed against airplane crash. Two problems arise: first, the local problem of penetration as well as local destruction of the building and secondly the airplane induced vibrations of the whole building which cause loadings for secondary systems (equipment). This paper deals especially with the second problem. Floor response spectra due to airplane crash are presented for two different power plant buildings. The influence of various parameters (time history of excitation, direction and location of impact, mathematical model, soil, damping, etc.) are discussed. A comparison with the results of earthquake loading is given. Suggestions are made for developing suitable floor design spectra and using them to analyse multidegree-of-freedom systems. However, the paper gives only a partial answer to the questions arising because of some important restrictions which had to be made. Studies concerning these restrictions are still being conducted and will be presented in a separate paper. (Auth.)

  19. Carbon cost of plant nitrogen acquisition: global carbon cycle impact from an improved plant nitrogen cycle in the Community Land Model.

    Science.gov (United States)

    Shi, Mingjie; Fisher, Joshua B; Brzostek, Edward R; Phillips, Richard P

    2016-03-01

    Plants typically expend a significant portion of their available carbon (C) on nutrient acquisition - C that could otherwise support growth. However, given that most global terrestrial biosphere models (TBMs) do not include the C cost of nutrient acquisition, these models fail to represent current and future constraints to the land C sink. Here, we integrated a plant productivity-optimized nutrient acquisition model - the Fixation and Uptake of Nitrogen Model - into one of the most widely used TBMs, the Community Land Model. Global plant nitrogen (N) uptake is dynamically simulated in the coupled model based on the C costs of N acquisition from mycorrhizal roots, nonmycorrhizal roots, N-fixing microbes, and retranslocation (from senescing leaves). We find that at the global scale, plants spend 2.4 Pg C yr(-1) to acquire 1.0 Pg N yr(-1) , and that the C cost of N acquisition leads to a downregulation of global net primary production (NPP) by 13%. Mycorrhizal uptake represented the dominant pathway by which N is acquired, accounting for ~66% of the N uptake by plants. Notably, roots associating with arbuscular mycorrhizal (AM) fungi - generally considered for their role in phosphorus (P) acquisition - are estimated to be the primary source of global plant N uptake owing to the dominance of AM-associated plants in mid- and low-latitude biomes. Overall, our coupled model improves the representations of NPP downregulation globally and generates spatially explicit patterns of belowground C allocation, soil N uptake, and N retranslocation at the global scale. Such model improvements are critical for predicting how plant responses to altered N availability (owing to N deposition, rising atmospheric CO2 , and warming temperatures) may impact the land C sink. © 2015 John Wiley & Sons Ltd.

  20. Plant communities as drivers of soil respiration: pathways, mechanisms, and significance for global change

    Science.gov (United States)

    Metcalfe, D. B.; Fisher, R. A.; Wardle, D. A.

    2011-08-01

    Understanding the impacts of plant community characteristics on soil carbon dioxide efflux (R) is a key prerequisite for accurate prediction of the future carbon (C) balance of terrestrial ecosystems under climate change. However, developing a mechanistic understanding of the determinants of R is complicated by the presence of multiple different sources of respiratory C within soil - such as soil microbes, plant roots and their mycorrhizal symbionts - each with their distinct dynamics and drivers. In this review, we synthesize relevant information from a wide spectrum of sources to evaluate the current state of knowledge about plant community effects on R, examine how this information is incorporated into global climate models, and highlight priorities for future research. Despite often large variation amongst studies and methods, several general trends emerge. Mechanisms whereby plants affect R may be grouped into effects on belowground C allocation, aboveground litter properties and microclimate. Within vegetation types, the amount of C diverted belowground, and hence R, may be controlled mainly by the rate of photosynthetic C uptake, while amongst vegetation types this should be more dependent upon the specific C allocation strategies of the plant life form. We make the case that plant community composition, rather than diversity, is usually the dominant control on R in natural systems. Individual species impacts on R may be largest where the species accounts for most of the biomass in the ecosystem, has very distinct traits to the rest of the community and/or modulates the occurrence of major natural disturbances. We show that climate vegetation models incorporate a number of pathways whereby plants can affect R, but that simplifications regarding allocation schemes and drivers of litter decomposition may limit model accuracy. We also suggest that under a warmer future climate, many plant communities may shift towards dominance by fast growing plants which

  1. Transcriptional Responses in the Hemiparasitic Plant Triphysaria versicolor to Host Plant Signals1[w

    Science.gov (United States)

    Matvienko, Marta; Torres, Manuel J.; Yoder, John I.

    2001-01-01

    Parasitic plants in the Scrophulariaceae use chemicals released by host plant roots to signal developmental processes critical for heterotrophy. Haustoria, parasitic plant structures that attach to and invade host roots, develop on roots of the hemiparasitic plant Triphysaria versicolor within a few hours of exposure to either maize (Zea mays) root exudate or purified haustoria-inducing factors. We prepared a normalized, subtractive cDNA library enriched for transcripts differentially abundant in T. versicolor root tips treated with the allelopathic quinone 2,6-dimethoxybenzoquinone (DMBQ). Northern analyses estimated that about 10% of the cDNAs represent transcripts strongly up-regulated in roots exposed to DMBQ. Northern and reverse northern analyses demonstrated that most DMBQ-responsive messages were similarly up-regulated in T. versicolor roots exposed to maize root exudates. From the cDNA sequences we assembled a unigene set of 137 distinct transcripts and assigned functions by homology comparisons. Many of the proteins encoded by the transcripts are predicted to function in quinone detoxification, whereas others are more likely associated with haustorium development. The identification of genes transcriptionally regulated by haustorium-inducing factors provides a framework for dissecting genetic pathways recruited by parasitic plants during the transition to heterotrophic growth. PMID:11553755

  2. Climate change drives a shift in peatland ecosystem plant community: implications for ecosystem function and stability.

    Science.gov (United States)

    Dieleman, Catherine M; Branfireun, Brian A; McLaughlin, James W; Lindo, Zoë

    2015-01-01

    The composition of a peatland plant community has considerable effect on a range of ecosystem functions. Peatland plant community structure is predicted to change under future climate change, making the quantification of the direction and magnitude of this change a research priority. We subjected intact, replicated vegetated poor fen peat monoliths to elevated temperatures, increased atmospheric carbon dioxide (CO2 ), and two water table levels in a factorial design to determine the individual and synergistic effects of climate change factors on the poor fen plant community composition. We identify three indicators of a regime shift occurring in our experimental poor fen system under climate change: nonlinear decline of Sphagnum at temperatures 8 °C above ambient conditions, concomitant increases in Carex spp. at temperatures 4 °C above ambient conditions suggesting a weakening of Sphagnum feedbacks on peat accumulation, and increased variance of the plant community composition and pore water pH through time. A temperature increase of +4 °C appeared to be a threshold for increased vascular plant abundance; however the magnitude of change was species dependent. Elevated temperature combined with elevated CO2 had a synergistic effect on large graminoid species abundance, with a 15 times increase as compared to control conditions. Community analyses suggested that the balance between dominant plant species was tipped from Sphagnum to a graminoid-dominated system by the combination of climate change factors. Our findings indicate that changes in peatland plant community composition are likely under future climate change conditions, with a demonstrated shift toward a dominance of graminoid species in poor fens. © 2014 John Wiley & Sons Ltd.

  3. Changes in soil bacterial communities induced by the invasive plant Pennisetum setaceum in a semiarid environment

    Science.gov (United States)

    Rodriguez-Caballero, Gema; Caravaca, Fuensanta; del Mar Alguacil, María; Fernández-López, Manuel; José Fernández-González, Antonio; García-Orenes, Fuensanta; Roldán, Antonio

    2016-04-01

    Invasive alien species are considered as a global threat being among the main causes of biodiversity loss. Plant invasions have been extensively studied from different disciplines with the purpose of identifying predictor traits of invasiveness and finding solutions. However, less is known about the implication of the rhizosphere microbiota in these processes, even when it is well known the importance of the interaction between plant rhizosphere and microbial communities. The objective of this study was to determine whether native and invasive plants support different bacterial communities in their rhizospheres and whether there are bacterial indicator species that might be contributing to the invasion process of these ecosystems. We carried out a study in five independent locations under Mediterranean semiarid conditions, where the native Hyparrhenia hirta is being displaced by Pennisetum setaceum, an aggressive invasive Poaceae and soil bacterial communities were amplified and 454-pyrosequenced. Changes in the composition and structure of the bacterial communities, owing to the invasive status of the plant, were detected when the richness and alpha-diversity estimators were calculated as well as when we analyzed the PCoA axes scores. The Indicator Species Analysis results showed a higher number of indicators for invaded communities at all studied taxonomic levels. In conclusion, the effect of the invasiveness and its interaction with the soil location has promoted shifts in the rhizosphere bacterial communities which might be facilitating the invader success in these ecosystems.

  4. Wastewater treatment plant effluent introduces recoverable shifts in microbial community composition in urban streams

    Science.gov (United States)

    Ledford, S. H.; Price, J. R.; Ryan, M. O.; Toran, L.; Sales, C. M.

    2017-12-01

    New technologies are allowing for intense scrutiny of the impact of land use on microbial communities in stream networks. We used a combination of analytical chemistry, real-time polymerase chain reaction (qPCR) and targeted amplicon sequencing for a preliminary study on the impact of wastewater treatment plant effluent discharge on urban streams. Samples were collected on two dates above and below treatment plants on the Wissahickon Creek, and its tributary, Sandy Run, in Montgomery County, PA, USA. As expected, effluent was observed to be a significant source of nutrients and human and non-specific fecal associated taxa. There was an observed increase in the alpha diversity at locations immediately below effluent outflows, which contributed many taxa involved in wastewater treatment processes and nutrient cycling to the stream's microbial community. Unexpectedly, modeling of microbial community shifts along the stream was not controlled by concentrations of measured nutrients. Furthermore, partial recovery, in the form of decreasing abundances of bacteria and nutrients associated with wastewater treatment plant processes, nutrient cycling bacteria, and taxa associated with fecal and sewage sources, was observed between effluent sources. Antecedent moisture conditions impacted overall microbial community diversity, with higher diversity occurring after rainfall. These findings hint at resilience in stream microbial communities to recover from wastewater treatment plant effluent and are vital to understanding the impacts of urbanization on microbial stream communities.

  5. Planting Seeds to Grow Healthy Children: Strategic Community Partnerships.

    Science.gov (United States)

    Alicea-Planas, Jessica; Sullivan, Kelly; Tran, Hang; Cruz, Anna

    2018-02-01

    More than one third of U.S adults are considered obese, and childhood obesity has more than doubled in the past 30 years. Food security can influence obesity, in particular, within inner cities where access to healthy food is often limited. The use of a mobile food truck program (with refrigeration) was implemented in two large inner cities in Connecticut as part of an initiative aimed at helping low-income families with young children gain access to healthy food and nutrition education. Collaborating with community child care centers was used. The experiences of the families who participated in the program were assessed via focus groups. Main ideas derived from the focus groups were participant satisfaction with money saving suggestions, ideas for how to make healthier choices, and excitement about opportunities to receive foods that they would not normally buy. This innovative mobile food truck program demonstrated the value of strategic community partnerships to influence health.

  6. Herbivore Impact on Tundra Plant Community Dynamics Using Long-term Remote Sensing Observation

    Science.gov (United States)

    Yu, Q.; Engstrom, R.; Shiklomanov, N. I.

    2014-12-01

    Arctic tundra biome is now experiencing dramatic environmental changes accentuated by summer sea-ice decline, permafrost thaw, and shrub expansion. Multi-decadal time-series of the Normalized Difference Vegetation Index (NDVI, a spectral metric of vegetation productivity) shows an overall "greening" trend across the Arctic tundra biome. Regional trends in climate plausibly explain large-scale patterns of increasing plant productivity, as diminished summer sea-ice extent warms the adjacent land causing tundra vegetation to respond positively (increased photosynthetic aboveground biomass). However, at more local scales, there is a great deal of spatial variability in NDVI trends that likely reflects differences in hydrology and soil conditions, disturbance history, and use by wildlife and humans. Particularly, habitat use by large herbivores, such as reindeer and caribou, has large impacts on vegetation dynamics at local and regional scales, but the role of herbivores in modulating the response of vegetation to warming climate has received little attention. This study investigates regional tundra plant community dynamics within inhabits of different sizes of wild caribou/reindeer herds across the Arctic using GIMMS NDVI (Normalized Difference Vegetation Index) 3g data product. The Taimyr herd in Russia is one of the largest herds in the world with a population increase from 450,000 in 1975 to about 1 million animals in 2000. The population of the porcupine caribou herd has fluctuated in the past three decades between 100,000 and 180,000. Time-series of the maximum NDVI within the inhabit area of the Taimyr herd has increased about 2% per decade over the past three decades, while within the inhabit area of the Porcupine herd the maximum NDVI has increased about 5% per decade. Our results indicate that the impact of large herbivores can be detected from space and further analyses on seasonal dynamics of vegetation indices and herbivore behavior may provide more

  7. Sensitivity of nuclear power plant structural response to aircraft impact

    International Nuclear Information System (INIS)

    Buchhardt, F.; Magiera, G.; Matthees, W.; Weber, M.

    1984-01-01

    In this paper a sensitivity study for aircraft impact is performed concerning the excitation of internal components, with particular regard to nonlinear structural material behaviour in the impact area. The nonlinear material values are varied within the bandwidth of suitable material strength, depending on local stiffness pre-calculations. The analyses are then performed on a globally discretized three-dimensional finite element model of a nuclear power plant, using a relatively fine mesh. For specified nodal points results are evaluated by comparing their response spectra. (Author) [pt

  8. The Upper Mississippi River floodscape: spatial patterns of flood inundation and associated plant community distributions

    Science.gov (United States)

    DeJager, Nathan R.; Rohweder, Jason J.; Yin, Yao; Hoy, Erin E.

    2016-01-01

    Questions How is the distribution of different plant communities associated with patterns of flood inundation across a large floodplain landscape? Location Thirty-eight thousand nine hundred and seventy hectare of floodplain, spanning 320 km of the Upper Mississippi River (UMR). Methods High-resolution elevation data (Lidar) and 30 yr of daily river stage data were integrated to produce a ‘floodscape’ map of growing season flood inundation duration. The distributions of 16 different remotely sensed plant communities were quantified along the gradient of flood duration. Results Models fitted to the cumulative frequency of occurrence of different vegetation types as a function of flood duration showed that most types exist along a continuum of flood-related occurrence. The diversity of community types was greatest at high elevations (0–10 d of flooding), where both upland and lowland community types were found, as well as at very low elevations (70–180 d of flooding), where a variety of lowland herbaceous communities were found. Intermediate elevations (20–60 d of flooding) tended to be dominated by floodplain forest and had the lowest diversity of community types. Conclusions Although variation in flood inundation is often considered to be the main driver of spatial patterns in floodplain plant communities, few studies have quantified flood–vegetation relationships at broad scales. Our results can be used to identify targets for restoration of historical hydrological regimes or better anticipate hydro-ecological effects of climate change at broad scales.

  9. [Effects of alien species Robinia pseudoacacia on plant community functional structure in hilly-gully region of Loess Plateau, China.

    Science.gov (United States)

    Zhu, Duo Ju; Wen, Zhong Ming; Zhang, Jing; Tao, Yu; Zeng, Hong Wen; Tang, Yang

    2018-02-01

    To investigate the effects of the introduction of Robinia pseudoacacia on the functional structure of plant communities, we selected paired-plots of R. pseudoacacia communities and native plant communities across different vegetation zones, i.e., steppe zone, forest-steppe zone, forest zone in hilly-gully region of Loess Plateau, China. We measured several functional characteristics and then compared the functional structures of R. pseudoacacia and native plant communities in different vegetation zones. The results showed that the variation of the functional traits across different vegetation zones were consistent in R. pseudoacacia community and native plant community, including leaf carbon concentration, leaf nitrogen concentration, leaf phosphorus concentration, specific leaf area, and leaf tissue density. The leaf carbon concentration, leaf nitrogen concentration, and specific leaf area of the R. pseudoacacia community were significantly higher than those of the native plant community. The trend of change that the functional diversity indices, i.e., FR ic , FE ve , FD iv , FD is , Rao of the R. pseudoacacia community and the native plant community with vegetation zones were different. The introduction of R. pseudoacacia enhanced the plant community functional diversity in the forest zone but reduced community functional diversity in the steppe zone.

  10. Plant Communities Rather than Soil Properties Structure Arbuscular Mycorrhizal Fungal Communities along Primary Succession on a Mine Spoil

    Czech Academy of Sciences Publication Activity Database

    Krüger, Claudia; Kohout, Petr; Janoušková, Martina; Püschel, David; Frouz, J.; Rydlová, Jana

    2017-01-01

    Roč. 8, APR 20 (2017), s. 1-16, č. článku 719. ISSN 1664-302X R&D Projects: GA ČR GA13-10377S; GA ČR GA15-05466S Institutional support: RVO:67985939 Keywords : biodiversity * community ecology * fungal and plant succession Subject RIV: EH - Ecology, Behaviour OBOR OECD: Ecology Impact factor: 4.076, year: 2016

  11. Ignored fungal community in activated sludge wastewater treatment plants: diversity and altitudinal characteristics.

    Science.gov (United States)

    Niu, Lihua; Li, Yi; Xu, Lingling; Wang, Peifang; Zhang, Wenlong; Wang, Chao; Cai, Wei; Wang, Linqiong

    2017-02-01

    Fungi are important contributors to the various functions of activated sludge wastewater treatment plants (WWTPs); however, the diversity and geographic characteristics of fungal populations have remained vastly unexplored. Here, quantitative polymerase chain reaction and 454 pyrosequencing were combined to investigate the abundance and diversity of the activated sludge fungal communities from 18 full-scale municipal WWTPs in China. Phylogenetic taxonomy revealed that the members of the fungal communities were assigned to 7 phyla and 195 genera. Ascomycota and Basidiomycota were the most abundant phyla, dominated by Pluteus, Wickerhamiella, and Penicillium. Twenty-three fungal genera, accounting for 50.1 % of the total reads, were shared by 18 WWTPs and constituted a core fungal community. The fungal communities presented similar community diversity but different community structures across the WWTPs. Significant distance decay relationships were observed for the dissimilarity in fungal community structure and altitudinal distance between WWTPs. Additionally, the community evenness increased from 0.25 to 0.7 as the altitude increased. Dissolved oxygen and the C/N ratio were determined to be the most dominant contributors to the variation in fungal community structure via redundancy analysis. The observed data demonstrated the diverse occurrence of fungal species and gave a marked view of fungal community characteristics based on the previously unexplored fungal communities in activated sludge WWTPs.

  12. Biomass, Leaf Area, and Resource Availability of Kudzu Dominated Plant Communities Following Herbicide Treatment

    Energy Technology Data Exchange (ETDEWEB)

    L.T. Rader

    2001-10-01

    Kudzu is an exotic vine that threatens the forests of the southern U.S. Five herbicides were tested with regard to their efficacy in controlling kudzu, community recover was monitored, and interactions with planted pines were studied. The sites selected were old farm sites dominated by kudzu.These were burned following herbicide treatment. The herbicides included triclopyr, clopyralid, metsulfuron, tebuthiuron, and picloram plus 2,4-D. Pine seedlings were planted the following year. Regression equations were developed for predicting biomass and leaf area. Four distinct plant communities resulted from the treatments. The untreated check continued to be kudzu dominated. Blackberry dominated the clopyradid treatment. Metsulfron, trychlopyr and picloram treated sites resulted in herbaceous dominated communities. The tebuthiuron treatment maintained all vegetation low.

  13. Quantifying human response capabilities towards tsunami threats at community level

    Science.gov (United States)

    Post, J.; Mück, M.; Zosseder, K.; Wegscheider, S.; Taubenböck, H.; Strunz, G.; Muhari, A.; Anwar, H. Z.; Birkmann, J.; Gebert, N.

    2009-04-01

    Decision makers at the community level need detailed information on tsunami risks in their area. Knowledge on potential hazard impact, exposed elements such as people, critical facilities and lifelines, people's coping capacity and recovery potential are crucial to plan precautionary measures for adaptation and to mitigate potential impacts of tsunamis on society and the environment. A crucial point within a people-centred tsunami risk assessment is to quantify the human response capabilities towards tsunami threats. Based on this quantification and spatial representation in maps tsunami affected and safe areas, difficult-to-evacuate areas, evacuation target points and evacuation routes can be assigned and used as an important contribution to e.g. community level evacuation planning. Major component in the quantification of human response capabilities towards tsunami impacts is the factor time. The human response capabilities depend on the estimated time of arrival (ETA) of a tsunami, the time until technical or natural warning signs (ToNW) can be received, the reaction time (RT) of the population (human understanding of a tsunami warning and the decision to take appropriate action), the evacuation time (ET, time people need to reach a safe area) and the actual available response time (RsT = ETA - ToNW - RT). If RsT is larger than ET, people in the respective areas are able to reach a safe area and rescue themselves. Critical areas possess RsT values equal or even smaller ET and hence people whin these areas will be directly affected by a tsunami. Quantifying the factor time is challenging and an attempt to this is presented here. The ETA can be derived by analyzing pre-computed tsunami scenarios for a respective area. For ToNW we assume that the early warning center is able to fulfil the Indonesian presidential decree to issue a warning within 5 minutes. RT is difficult as here human intrinsic factors as educational level, believe, tsunami knowledge and experience

  14. Plant transducers of the endoplasmic reticulum unfolded protein response

    KAUST Repository

    Iwata, Yuji; Koizumi, Nozomu

    2012-01-01

    The unfolded protein response (UPR) activates a set of genes to overcome accumulation of unfolded proteins in the endoplasmic reticulum (ER), a condition termed ER stress, and constitutes an essential part of ER protein quality control that ensures efficient maturation of secretory and membrane proteins in eukaryotes. Recent studies on Arabidopsis and rice identified the signaling pathway in which the ER membrane-localized ribonuclease IRE1 (inositol-requiring enzyme 1) catalyzes unconventional cytoplasmic splicing of mRNA, thereby producing the active transcription factor Arabidopsis bZIP60 (basic leucine zipper 60) and its ortholog in rice. Here we review recent findings identifying the molecular components of the plant UPR, including IRE1/bZIP60 and the membrane-bound transcription factors bZIP17 and bZIP28, and implicating its importance in several physiological phenomena such as pathogen response. © 2012 Elsevier Ltd.

  15. Plant transducers of the endoplasmic reticulum unfolded protein response

    KAUST Repository

    Iwata, Yuji

    2012-12-01

    The unfolded protein response (UPR) activates a set of genes to overcome accumulation of unfolded proteins in the endoplasmic reticulum (ER), a condition termed ER stress, and constitutes an essential part of ER protein quality control that ensures efficient maturation of secretory and membrane proteins in eukaryotes. Recent studies on Arabidopsis and rice identified the signaling pathway in which the ER membrane-localized ribonuclease IRE1 (inositol-requiring enzyme 1) catalyzes unconventional cytoplasmic splicing of mRNA, thereby producing the active transcription factor Arabidopsis bZIP60 (basic leucine zipper 60) and its ortholog in rice. Here we review recent findings identifying the molecular components of the plant UPR, including IRE1/bZIP60 and the membrane-bound transcription factors bZIP17 and bZIP28, and implicating its importance in several physiological phenomena such as pathogen response. © 2012 Elsevier Ltd.

  16. Community based bioremediation: grassroots responses to urban soil contamination

    Directory of Open Access Journals (Sweden)

    Scott Kellogg

    2016-12-01

    Full Text Available The past 150 years of industrial processes have left a legacy of toxicity in the soils of today’s urban environments. Exposure to soil based pollutants disproportionately affects low-income communities who are frequently located within formerly industrialized zones. Both gardeners, who come into direct contact with soil, as well as those who eat the products grown in the soil, are at risk to exposure from industrial contaminants. Options for low-income communities for remediating contaminated soils are limited, with most remediation work being carried out by costly engineering firms. Even more problematic is the overall lack of awareness and available information regarding safety and best practices with soils. In response to these challenges, a grassroots movement has emerged that seeks to empower urban residents with the tools and information necessary to address residual industrial toxicity in their ecosystems. Focusing on methods that are simple and affordable, this movement wishes to remove the barriers of cost and technical expertise that may be otherwise prohibitive. This paper will give an overview of this exemplar of generative justice, looking at case studies of organizations that have been successful in implementing these strategies.

  17. Gender differentiation in community responses to AIDS in rural Uganda.

    Science.gov (United States)

    Kanyamurwa, J M; Ampek, G T

    2007-01-01

    AIDS has been reported in Africa to push households into poverty and chronic food insecurity. At the same time there are reports of significant household resilience to AIDS. This study explored how a mature epidemic in rural Uganda has affected rural farming households. It focused on gender differences in the experience of AIDS and, in particular, household capabilities to sustain livelihoods. The study compared the vulnerability of male- and female-headed households in relation to their ability to mitigate human resource losses, as well as their access to natural and physical resources, to social networks and to finance capital for production. The findings suggest that when rural households are affected by AIDS, depleting productive resources and directing resources towards immediate needs, there are gender differences in responses to, and in impacts of, the epidemic due to the different resources available to male- and female- headed households. Female-headed households were found to be more vulnerable to AIDS than male-headed counterparts. Women's remarriage opportunities were lower than men's, they faced greater risk of losing control over land and livestock and they accessed less state and private sector support. Women-headed households were more dependent on livelihood support from non-governmental organizations, which were found to provide both welfare and credit support to female-headed households affected by AIDS. Women were found to play an important role in social networks and resources at community level but themselves received little support from many formal community networks and services.

  18. RESPONSE OF TOMATO PLANTS EXPOSED TO TREATMENT WITH NANOPARTICLES

    Directory of Open Access Journals (Sweden)

    Tommaso Giordani

    2012-07-01

    Full Text Available In this work the response of Tomato plants cv. Micro-Tom to nanoparticles (NPs treatment was investigated. Tomato seedlings were grown in hydroponic condition and NPs treatments were carried out by adding Fe3O4 or TiO2 NPs to nutrient solution. At the end of treatments, NPs root uptake and tissue deposition were investigated using Environmental Scanning Electron Microscope, equipped with energy dispersive spectroscopy for chemical identification. At morphological level, one week after the beginning of NP treatment, seedlings grown with high concentration of TiO2 NPs showed an abnormal proliferation of root hairs, as compared to the control seedlings and to the seedlings exposed to Fe3O4 NPs, Shoot morphology did not differ in tomato seedlings grown under different conditions and no symptoms of toxicity were observed in NP-treated plants. In order to analyse genetic effects of NPs treatments, RNA transcription was studied in roots of NP-exposed and control plants by Illumina RNA sequencing, evidencing the induction of transposable elements.

  19. Evapotranspiration over spatially extensive plant communities in the Big Cypress National Preserve, southern Florida, 2007-2010

    Science.gov (United States)

    Shoemaker, W. Barclay; Lopez, Christian D.; Duever, Michael J.

    2011-01-01

    Evapotranspiration (ET) was quantified over plant communities within the Big Cypress National Preserve (BCNP) using the eddy covariance method for a period of 3 years from October 2007 to September 2010. Plant communities selected for study included Pine Upland, Wet Prairie, Marsh, Cypress Swamp, and Dwarf Cypress. These plant communities are spatially extensive in southern Florida, and thus, the ET measurements described herein can be applied to other humid subtropical locations such as the Everglades.

  20. Use of Medical Plants in Schools Communities from Sinop, Mato Grosso.

    Directory of Open Access Journals (Sweden)

    A. C. M. Urtado

    2013-03-01

    Full Text Available Abstract: This study was conducted in Sinop, Mato Grosso, on two school communities. It was applied semi-structured questionnaires with questions focused on socioeconomic and the use of medicinal plants. It has as finality proved the effective use of medicinal plants on the everyday and a levy of the most used plant. The general profile of the respondents has shown that the women detain the major part of the knowledge, and that pass this uses to the future generations and friends, and find these plants on specialty stores, backyards, supermarket, root stores, bush and fairs. The plants that were found more frequently was (Ruta graveolens L., Babosa (Aloe vera L., Erva-Cidreira (Lippia alba Mill., Erva-Santa-Maria (Chenopodium ambrosioides L., Boldo (Plectranthus amboinicus Sp