Rapid Increases in forest understory diversity and productivity following a mountain pine beetle (Dendroctonus ponderosae) outbreak in pine forests.

Science.gov (United States)

Pec, Gregory J; Karst, Justine; Sywenky, Alexandra N; Cigan, Paul W; Erbilgin, Nadir; Simard, Suzanne W; Cahill, James F

2015-01-01

The current unprecedented outbreak of mountain pine beetle (Dendroctonus ponderosae) in lodgepole pine (Pinus contorta) forests of western Canada has resulted in a landscape consisting of a mosaic of forest stands at different stages of mortality. Within forest stands, understory communities are the reservoir of the majority of plant species diversity and influence the composition of future forests in response to disturbance. Although changes to stand composition following beetle outbreaks are well documented, information on immediate responses of forest understory plant communities is limited. The objective of this study was to examine the effects of D. ponderosae-induced tree mortality on initial changes in diversity and productivity of understory plant communities. We established a total of 110 1-m2 plots across eleven mature lodgepole pine forests to measure changes in understory diversity and productivity as a function of tree mortality and below ground resource availability across multiple years. Overall, understory community diversity and productivity increased across the gradient of increased tree mortality. Richness of herbaceous perennials increased with tree mortality as well as soil moisture and nutrient levels. In contrast, the diversity of woody perennials did not change across the gradient of tree mortality. Understory vegetation, namely herbaceous perennials, showed an immediate response to improved growing conditions caused by increases in tree mortality. How this increased pulse in understory richness and productivity affects future forest trajectories in a novel system is unknown.

Rapid Increases in forest understory diversity and productivity following a mountain pine beetle (Dendroctonus ponderosae outbreak in pine forests.

Directory of Open Access Journals (Sweden)

Gregory J Pec

Full Text Available The current unprecedented outbreak of mountain pine beetle (Dendroctonus ponderosae in lodgepole pine (Pinus contorta forests of western Canada has resulted in a landscape consisting of a mosaic of forest stands at different stages of mortality. Within forest stands, understory communities are the reservoir of the majority of plant species diversity and influence the composition of future forests in response to disturbance. Although changes to stand composition following beetle outbreaks are well documented, information on immediate responses of forest understory plant communities is limited. The objective of this study was to examine the effects of D. ponderosae-induced tree mortality on initial changes in diversity and productivity of understory plant communities. We established a total of 110 1-m2 plots across eleven mature lodgepole pine forests to measure changes in understory diversity and productivity as a function of tree mortality and below ground resource availability across multiple years. Overall, understory community diversity and productivity increased across the gradient of increased tree mortality. Richness of herbaceous perennials increased with tree mortality as well as soil moisture and nutrient levels. In contrast, the diversity of woody perennials did not change across the gradient of tree mortality. Understory vegetation, namely herbaceous perennials, showed an immediate response to improved growing conditions caused by increases in tree mortality. How this increased pulse in understory richness and productivity affects future forest trajectories in a novel system is unknown.

Understory biomass from southern pine forests as a fuel source

Energy Technology Data Exchange (ETDEWEB)

Ku, T.T. [Univ. of Arkansas, Monticello, AR (United States); Baker, J.B. [USDA Forest Service, Monticello, AR (United States)

1993-12-31

The energy crisis in the US in the late 1970s led to accelerated research on renewable energy resources. The use of woody biomass, harvested from pine forests in the southern US, as a renewable energy source would not only provide an efficient energy alternative to forest industries, but its use would also reduce understory competition and accelerate growth of overstory crop trees. This study was initiated in the early 1980s to investigate the feasibility and applicability of the use of understory vegetation as a possible energy fuel resource. All woody understory vegetation [<14 cm (<5.5 in) in dbh], on 0.2 ha (0.5 ac) plots that represented a range of stand/site conditions of pine stands located in twelve southern Arkansas counties and two northern Louisiana parishes were characterized, quantified, and harvested. Based on the biomass yield from 720 subplots nested within 40 main plots, the top five dominant species in the understory, based on number and size were: Red maple, red oaks, pines, sweetgum, and winged elm. Some other species occurring, but in smaller proportions, were flowering dogwood, beautyberry, white oaks, black gum, wax myrtle, hickories, persimmon, and ashes. Most of these species are deciduous hardwoods that provide high BTU output upon burning. The average yield of chipped understory biomass was 23.5 T/ha with no difference occurring between summer and winter harvests. A predictive model of understory biomass production was developed using a step-wise multivariate regression analysis. In relation to forest type, high density pine stands produced 53% more understory biomass than high density pine-hardwood stands. The average moisture content of biomass was significantly lower when harvested in winter than when harvested in summer.

Nitrogen Addition and Understory Removal but Not Soil Warming Increased Radial Growth of Pinus cembra at Treeline in the Central Austrian Alps

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Andreas Gruber

2018-05-01

Full Text Available Beside low temperatures, limited tree growth at the alpine treeline may also be attributed to a lack of available soil nutrients and competition with understory vegetation. Although intra-annual stem growth of Pinus cembra has been studied intensively at the alpine treeline, the responses of radial growth to soil warming, soil fertilization, and below ground competition awaits clarification. In this study we quantified the effects of nitrogen (N fertilization, soil warming, and understory removal on stem radial growth of P. cembra at treeline. Soil warming was achieved by roofing the forest floor with a transparent polyvinyl skin, while understory competition was prevented by shading the forest floor with a non-transparent foil around six trees each. Six trees received N- fertilization and six other trees served as controls. Stem growth was monitored with band dendrometers during the growing seasons 2012–2014. Our 3 years experiment showed that soil warming had no considerable effect on radial growth. Though understory removal through shading was accompanied by root-zone cooling, understory removal as well as N fertilization led to a significant increase in radial growth. Hardly affected was tree root biomass, while N-fertilization and understory removal significantly increased in 100-needle surface area and 100-needle dry mass, implying a higher amount of N stored in needles. Overall, our results demonstrate that beside low temperatures, tree growth at cold-climate boundaries may also be limited by root competition for nutrients between trees and understory vegetation. We conclude that tree understory interactions may also control treeline dynamics in a future changing environment.

Variability in Light Use Efficiency With Changes in Vegetation Structure and Understory, Using a Temporally Changing Flux Footprint at the BERMS Old Jack Pine Site

Science.gov (United States)

Chasmer, L.; Barr, A.; Black, A.; Hopkinson, C.; Kljun, N.; McCaughey, H.; Treitz, P.; Shashkov, A.; Zha, T.

2006-12-01

Satellite remote sensing algorithms of vegetation gross primary productivity (GPP) often include a light use efficiency (LUE) term that varies depending on meteorological constraints and biome type. LUE is defined as the carbon fixed per mole of photosynthetically active radiation (PAR) absorbed by the canopy (APAR). LUE estimated using GPP from eddy covariance data is complex and changes over short time periods as the available resources (soil moisture, light, temperature, and nitrogen) vary. An understanding of the variability in LUE will improve local to regional estimates of GPP within complex vegetated land cover types using the variety of remote sensing technologies now available. This study examines variability in LUE and GPP at a mature jack pine site within the Fluxnet-Canada BERMS (Boreal Ecosystem Research and Monitoring Sites) study area using a flux footprint model (Kljun et al. 2004) and airborne lidar data (e.g. Chasmer et al. 2006). Three separate weeks of high frequency eddy covariance data are analyzed for June, July, and August 2002 to capture changes in photosynthesis and carbon uptake through the growing season with variations in precipitation and soil moisture. Footprint estimates are derived in half-hourly resolution to provide information on the spatial and temporal variation of the sources of measured C-fluxes. Airborne lidar directly samples ground topography and vegetation structure (i.e., canopy and understory height, gaps between trees, base of canopy), and may provide information on soil moisture and drainage at the ground surface via absorbed and reflected laser pulse energy. Two questions will be addressed specific to net ecosystem productivity (NEP) of the site as a whole, including parts of the ecosystem that may not be properly represented using eddy covariance techniques. These are: 1. How does C uptake and respiration spatially and temporally vary across the jack pine site? 2. How do vegetation characteristics vary with

Airborne laser scanner (LiDAR) proxies for understory light conditions

DEFF Research Database (Denmark)

Alexander, Cici; Moeslund, Jesper Erenskjold; Bøcher, Peder Klith

2013-01-01

to community structure. Angular canopy closure is more closely related to the direct and indirect light experienced by a plant or an animal than vertical canopy cover, but more challenging to estimate. We used airborne laser scanner (ALS) data to estimate canopy cover for 210 5-m radius vegetation plots......Canopy cover and canopy closure are two closely related measures of vegetation structure. They are used for estimating understory light conditions and their influence on a broad range of biological components in forest ecosystems, from the demography and population dynamics of individual species...... of azimuth and zenith angle intervals which contained points. We compared these estimates with field-based estimates using densiometer for 60 vegetation plots in forest. Finally, we compared ALS-based estimates of canopy cover and canopy closure to field-based estimates of understory light, based...

Monoterpene emissions from an understory species, Pteridium aquilinum

Science.gov (United States)

Madronich, Monica B.; Greenberg, James P.; Wessman, Carol A.; Guenther, Alex B.

2012-07-01

Monoterpene emissions from the dominant understory species Pteridium aquilinum (Bracken fern) in a mixed temperate forest were measured in the field during the summers of 2006, 2007 and 2008. The results showed that Bracken fern emitted monoterpenes at different rates depending if the plants were located in the understory or in open areas. Understory plants emitted monoterpene levels ranging from 0.002 to 13 μgC gdw-1 h-1. Open area plants emitted monoterpene levels ranging from 0.005 to 2.21 μgC gdw-1 h-1. During the summer of 2008 greenhouse studies were performed to complement the field studies. Only 3% of the greenhouse Bracken fern plants emitted substantial amounts of monoterpenes. The average emission, 0.15 μgC gdw-1 h-1 ± 0.9 μgC gdw-1 h-1, was much lower than that observed in the field. The factors controlling monoterpene emissions are not clear, but this study provides evidence of the potential importance of understory vegetation to ecosystem total hydrocarbon emissions and emphasizes the need for longer-term field studies.

Structural and floristic changes caused by gamma radiation in understory vegetation of two forest types in northern Wisconsin

International Nuclear Information System (INIS)

Zavitkovski, J.

1977-01-01

Structural and floristic changes of the understory vegetation of gamma-irradiated aspen and maple-aspen-birch (MAB) communities in northern Wisconsin were quantified by comparing the pre- and postirradiation floristic composition and vegetational cover. A size-dependent radiosensitivity was determined among three vegetational strata, the tall shrubs being the most sensitive, low shrubs intermediate, and herbs the most resistant. Corylus cornuta, whose nuclear characteristics indicated that it could be resistant, was very sensitive and was completely eliminated at exposures of 500 r/20-hr day or higher. The cover of Rubus strigosus, minimal before irradiation, increased manifold and accounted for most of the shrub cover 2 years after the conclusion of irradiation. Among herbs, Carex pensylvanica and Luzula acuminata were very resistant, and Trillium grandiflorum, Aralia nudicaulis, Oryzopsis asperifolia, and Clintonia borealis were very sensitive. The herbaceous stratum of the aspen type appeared more resistant than that of the MAB. This difference apparently resulted from differences in floristic composition of the two communities

Simulating Various Terrestrial and Uav LIDAR Scanning Configurations for Understory Forest Structure Modelling

Science.gov (United States)

Hämmerle, M.; Lukač, N.; Chen, K.-C.; Koma, Zs.; Wang, C.-K.; Anders, K.; Höfle, B.

2017-09-01

Information about the 3D structure of understory vegetation is of high relevance in forestry research and management (e.g., for complete biomass estimations). However, it has been hardly investigated systematically with state-of-the-art methods such as static terrestrial laser scanning (TLS) or laser scanning from unmanned aerial vehicle platforms (ULS). A prominent challenge for scanning forests is posed by occlusion, calling for proper TLS scan position or ULS flight line configurations in order to achieve an accurate representation of understory vegetation. The aim of our study is to examine the effect of TLS or ULS scanning strategies on (1) the height of individual understory trees and (2) understory canopy height raster models. We simulate full-waveform TLS and ULS point clouds of a virtual forest plot captured from various combinations of max. 12 TLS scan positions or 3 ULS flight lines. The accuracy of the respective datasets is evaluated with reference values given by the virtually scanned 3D triangle mesh tree models. TLS tree height underestimations range up to 1.84 m (15.30 % of tree height) for single TLS scan positions, but combining three scan positions reduces the underestimation to maximum 0.31 m (2.41 %). Combining ULS flight lines also results in improved tree height representation, with a maximum underestimation of 0.24 m (2.15 %). The presented simulation approach offers a complementary source of information for efficient planning of field campaigns aiming at understory vegetation modelling.

SIMULATING VARIOUS TERRESTRIAL AND UAV LIDAR SCANNING CONFIGURATIONS FOR UNDERSTORY FOREST STRUCTURE MODELLING

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M. Hämmerle

2017-09-01

Full Text Available Information about the 3D structure of understory vegetation is of high relevance in forestry research and management (e.g., for complete biomass estimations. However, it has been hardly investigated systematically with state-of-the-art methods such as static terrestrial laser scanning (TLS or laser scanning from unmanned aerial vehicle platforms (ULS. A prominent challenge for scanning forests is posed by occlusion, calling for proper TLS scan position or ULS flight line configurations in order to achieve an accurate representation of understory vegetation. The aim of our study is to examine the effect of TLS or ULS scanning strategies on (1 the height of individual understory trees and (2 understory canopy height raster models. We simulate full-waveform TLS and ULS point clouds of a virtual forest plot captured from various combinations of max. 12 TLS scan positions or 3 ULS flight lines. The accuracy of the respective datasets is evaluated with reference values given by the virtually scanned 3D triangle mesh tree models. TLS tree height underestimations range up to 1.84 m (15.30 % of tree height for single TLS scan positions, but combining three scan positions reduces the underestimation to maximum 0.31 m (2.41 %. Combining ULS flight lines also results in improved tree height representation, with a maximum underestimation of 0.24 m (2.15 %. The presented simulation approach offers a complementary source of information for efficient planning of field campaigns aiming at understory vegetation modelling.

Biomass and element pools of understory vegetation in the catchments of Čertovo Lake and Plešné Lake in the Bohemian Forest

Czech Academy of Sciences Publication Activity Database

Svoboda, M.; Matějka, K.; Kopáček, Jiří

2006-01-01

Roč. 61, Suppl. 20 (2006), S509-S521 ISSN 0006-3088 R&D Projects: GA ČR GA206/03/1583 Grant - others:MA(CZ) NAZV QG50105 Institutional research plan: CEZ:AV0Z60170517 Keywords : Norway spruce forest * understory vegetation Subject RIV: EH - Ecology, Behaviour Impact factor: 0.213, year: 2006

Resource Limitations Influence Growth and Vigor of Idaho Fescue, a Common Understory Species in Pacific Northwest Ponderosa Pine Forests

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Craig A. Carr

2016-12-01

Full Text Available Alterations in under-canopy resource availability associated with elevated ponderosa pine (Pinus ponderosa Dougl. abundance can negatively influence understory vegetation. Experimental evidence linking under-canopy resource availability and understory vegetation is scarce. Yet this information would be beneficial in developing management strategies to recover desired understory species. We tested the effects of varying nitrogen (N and light availability on Idaho fescue (Festuca idahoensis Elmer, the dominant understory species in ponderosa pine/Idaho fescue plant associations in eastern Oregon. In a greenhouse experiment, two levels of N (50 kg∙N∙ha−1 and 0 kg∙N∙ha−1 and shade (80% shade and 0% shade were applied in a split-plot design to individual potted plants grown in soil collected from high abundance pine stands. Plants grown in unshaded conditions produced greater root (p = 0.0027 and shoot (p = 0.0017 biomass and higher cover values (p = 0.0378 compared to those in the shaded treatments. The addition of N had little effect on plant growth (p = 0.1602, 0.5129, and 0.0853 for shoot biomass, root biomass, and cover, respectively, suggesting that soils in high-density ponderosa pine stands that lack understory vegetation were not N deficient and Idaho fescue plants grown in these soils were not N limited. Management activities that increase under-canopy light availability will promote the conditions necessary for Idaho fescue recovery. However, successful restoration may be constrained by a lack of residual fescue or the invasion of more competitive understory vegetation.

Post-Fire Peat Land Understory Plant in Rimba Panjang, Sumatera, Indonesia

Science.gov (United States)

Firdaus, L. N.; Nursal; Wulandari, Sri; Syafi'i, Wan; Fauziah, Yuslim

2017-12-01

The existence of understory plants during early post-fire succession is essential in term of natural post-fire ecological restoration. More than fifty percent of fire incidents in Riau, Sumatera, Indonesia occurred in shallow peat lands which have the huge impact on vegetation damage. This study aims to explore the understory plants species and diversity in post-fire peat land at Rimba Panjang, Kampar Regency, Sumatera, Indonesia. By using survey method, the observations were conducted on 150 plots which were distributed randomly over four locations based on the year after fire: 2009, 2014, 2015 and 2016. We found respectively 12, 14, 19 and 17 species at that sites with respective Shannon Wiener diversity index were 1.72, 2.00, 2.14 and 2.40. All the sites were dominated by Stenochlaena palustris (Burm.). Coverage percentage of understory vegetation were respectively 28.87%, 25.50%, 51.60% and 54.13%. Overall, we found 31 species of 17 familia. The result showed that the species composition, diversity index and coverage percentage of understory plant are likely to decrease in line with the length of time after the fire. Post peatland fires in Rimba Panjang are still having the characteristics of the peat swamp habitat which was dominated by Stenochlaena palustris (Burm.). Ecological restoration of that habitat is still possible, but it is necessary to consider technological and socio-economical aspects of local communities.

Nitrogen-addition effects on leaf traits and photosynthetic carbon gain of boreal forest understory shrubs.

Science.gov (United States)

Palmroth, Sari; Bach, Lisbet Holm; Nordin, Annika; Palmqvist, Kristin

2014-06-01

Boreal coniferous forests are characterized by fairly open canopies where understory vegetation is an important component of ecosystem C and N cycling. We used an ecophysiological approach to study the effects of N additions on uptake and partitioning of C and N in two dominant understory shrubs: deciduous Vaccinium myrtillus in a Picea abies stand and evergreen Vaccinium vitis-idaea in a Pinus sylvestris stand in northern Sweden. N was added to these stands for 16 and 8 years, respectively, at rates of 0, 12.5, and 50 kg N ha(-1) year(-1). N addition at the highest rate increased foliar N and chlorophyll concentrations in both understory species. Canopy cover of P. abies also increased, decreasing light availability and leaf mass per area of V. myrtillus. Among leaves of either shrub, foliar N content did not explain variation in light-saturated CO2 exchange rates. Instead photosynthetic capacity varied with stomatal conductance possibly reflecting plant hydraulic properties and within-site variation in water availability. Moreover, likely due to increased shading under P. abies and due to water limitations in the sandy soil under P. sylvestris, individuals of the two shrubs did not increase their biomass or shift their allocation between above- and belowground parts in response to N additions. Altogether, our results indicate that the understory shrubs in these systems show little response to N additions in terms of photosynthetic physiology or growth and that changes in their performance are mostly associated with responses of the tree canopy.

Understory Structure and Vascular Plant Diversity in Naturally Regenerated Deciduous Forests and Spruce Plantations on Similar Clear-Cuts: Implications for Forest Regeneration Strategy Selection

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ZhiQiang Fang

2014-04-01

Full Text Available The active effect of natural regeneration on understory vegetation and diversity on clear-cut forestlands, in contrast to conifer reforestation, is still controversial. Here we investigated differences in understory vegetation by comparing naturally regenerated deciduous forests (NR and reforested spruce plantations (SP aged 20–40 years on 12 similar clear-cuts of subalpine old-growth spruce-fir forests from the eastern Tibetan Plateau. We found that 283 of the 334 vascular plant species recorded were present in NR plots, while only 264 species occurred in SP plots. This was consistent with richer species, higher cover, and stem (or shoot density of tree seedlings, shrubs, and ferns in the NR plots than in the SP plots. Moreover, understory plant diversity was limited under dense canopy cover, which occurred more frequently in the SP plots. Our findings implied that natural deciduous tree regeneration could better preserve understory vegetation and biodiversity than spruce reforestation after clear-cutting. This result further informed practices to reduce tree canopy cover for spruce plantations or to integrate natural regeneration and reforestation for clear-cuts in order to promote understory vegetation and species diversity conservation.

Understory response to disturbance: an investigation of prescribed burning and understory thinning treatments

Science.gov (United States)

Benjamin J. Dolan; George R. Parker

2003-01-01

Lack of disturbance in the Central Hardwood Region has caused a decrease in abundance of shade-intolerant species, such as oaks (Quercus spp.) and hickories (Carya spp.), in the forest understory, while shade-tolerant species have proliferated. The goal of this research is to determine how two disturbances, prescribed fire and...

Limits to understory plant restoration following fuel-reduction treatments in a piñon-juniper woodland.

Science.gov (United States)

Redmond, Miranda D; Zelikova, Tamara J; Barger, Nichole N

2014-11-01

National fuel-reduction programs aim to reduce the risk of wildland fires to human communities and to restore forest and rangeland ecosystems to resemble their historical structure, function, and diversity. There are a number of factors, such as seed bank dynamics, post-treatment climate, and herbivory, which determine whether this latter goal may be achieved. Here, we examine the short-term (2 years) vegetation response to fuel-reduction treatments (mechanical mastication, broadcast burn, and pile burn) and seeding of native grasses on understory vegetation in an upland piñon-juniper woodland in southeast Utah. We also examine how wildlife herbivory affects the success of fuel-reduction treatments. Herbaceous cover increased in response to fuel-reduction treatments in all seeded treatments, with the broadcast burn and mastication having greater increases (234 and 160 %, respectively) in herbaceous cover than the pile burn (32 %). In the absence of seeding, herbaceous cover only increased in the broadcast burn (32 %). Notably, fuel-reduction treatments, but not seeding, strongly affected herbaceous plant composition. All fuel-reduction treatments increased the relative density of invasive species, especially in the broadcast burn, which shifted the plant community composition from one dominated by perennial graminoids to one dominated by annual forbs. Herbivory by wildlife reduced understory plant cover by over 40 % and altered plant community composition. If the primary management goal is to enhance understory cover while promoting native species abundance, our study suggests that mastication may be the most effective treatment strategy in these upland piñon-juniper woodlands. Seed applications and wildlife exclosures further enhanced herbaceous cover following fuel-reduction treatments.

[Effects of understory removal on soil greenhouse gas emissions in Carya cathayensis stands].

Science.gov (United States)

Liu, Juan; Chen, Xue-shuang; Wu, Jia-sen; Jiang, Pei-kun; Zhou, Guo-mo; Li, Yong-fu

2015-03-01

CO2, N2O and CH4 are important greenhouse gases, and soils in forest ecosystems are their important sources. Carya cathayensis is a unique tree species with seeds used for high-grade dry fruit and oil production. Understory vegetation management plays an important role in soil greenhouse gases emission of Carya cathayensis stands. A one-year in situ experiment was conducted to study the effects of understory removal on soil CO2, N2O and CH4 emissions in C. cathayensis plantation by closed static chamber technique and gas chromatography method. Soil CO2 flux had a similar seasonal trend in the understory removal and preservation treatments, which was high in summer and autumn, and low in winter and spring. N2O emission occurred mainly in summer, while CH4 emission showed no seasonal trend. Understory removal significantly decreased soil CO, emission, increased N2O emission and CH4 uptake, but had no significant effect on soil water soluble organic carbon and microbial biomass carbon. The global warming potential of soil greenhouse gases emitted in the understory removal. treatment was 15.12 t CO2-e . hm-2 a-1, which was significantly lower than that in understory preservation treatment (17.04 t CO2-e . hm-2 . a-1).

Involvement of allelopathy in inhibition of understory growth in red pine forests.

Science.gov (United States)

Kato-Noguchi, Hisashi; Kimura, Fukiko; Ohno, Osamu; Suenaga, Kiyotake

2017-11-01

Japanese red pine (Pinus densiflora Sieb. et Zucc.) forests are characterized by sparse understory vegetation although sunlight intensity on the forest floor is sufficient for undergrowth. The possible involvement of pine allelopathy in the establishment of the sparse understory vegetation was investigated. The soil of the red pine forest floor had growth inhibitory activity on six test plant species including Lolium multiflorum, which was observed at the edge of the forest but not in the forest. Two growth inhibitory substances were isolated from the soil and characterized to be 15-hydroxy-7-oxodehydroabietate and 7-oxodehydroabietic acid. Those compounds are probably formed by degradation process of resin acids. Resin acids are produced by pine and delivered into the soil under the pine trees through balsam and defoliation. Threshold concentrations of 15-hydroxy-7-oxodehydroabietate and 7-oxodehydroabietic acid for the growth inhibition of L. multiflorum were 30 and 10μM, respectively. The concentrations of 15-hydroxy-7-oxodehydroabietate and 7-oxodehydroabietic acid in the soil were 312 and 397μM, respectively, which are sufficient concentrations to cause the growth inhibition because of the threshold. These results suggest that those compounds are able to work as allelopathic agents and may prevent from the invasion of herbaceous plants into the forests by inhibiting their growth. Therefore, allelopathy of red pine may be involved in the formation of the sparse understory vegetation. Copyright © 2017 Elsevier GmbH. All rights reserved.

Partitioning understory evapotranspiration in semi-arid ecosystems in Namibia using the isotopic composition of water vapour

Science.gov (United States)

de Blécourt, Marleen; Gaj, Marcel; Holtorf, Kim-Kirsten; Gröngröft, Alexander; Brokate, Ralph; Himmelsbach, Thomas; Eschenbach, Annette

2016-04-01

In dry environments with a sparse vegetation cover, understory evapotranspiration is a major component of the ecosystem water balance. Consequently, knowledge on the size of evapotranspiration fluxes and the driving factors is important for our understanding of the hydrological cycle. Understory evapotranspiration is made up of soil evaporation and plant transpiration. Soil evaporation can be measured directly from patches free of vegetation. However, when understory vegetation is present distinguishing between soil evaporation and plant transpiration is challenging. In this study, we aim to partition understory evapotranspiration based on an approach that combines the measurements of water-vapour fluxes using the closed chamber method with measurements of the isotopic composition of water vapour. The measurements were done in the framework of SASSCAL (Southern African Science Service Centre for Climate Change and Adaptive Land Management). The study sites were located in three different semi-arid ecosystems in Namibia: thornbush savanna, Baikiaea woodland and shrubland. At each site measurements were done under tree canopies as well as at unshaded areas between the canopies. We measured evaporation from the bare soil and evapotranspiration from patches covered with herbaceous species and shrubs using a transparent chamber connected with an infrared gas analyser (LI-8100A, LICOR Inc.). The stable isotope composition of water vapour inside the chamber and depth profiles of soil water stable isotopes were determined in-situ using a tuneable off-axis integrated cavity output spectroscope (OA-ICOS, Los Gatos Research, DLT 100). Xylem samples were extracted using the cryogenic vacuum extraction method and the isotopic composition of the extracted water was measured subsequently with a cavity-ring-down spectrometer (CRDS L2120-i, Picarro Inc.). We will present the quantified fluxes of understory evapotranspiration measured in the three different ecosystems, show the

Arthropod prey of Wilson's Warblers in the understory of Douglas-fir forests

Science.gov (United States)

Hagar, J.C.; Dugger, K.M.; Starkey, E.E.

2007-01-01

Availability of food resources is an important factor in avian habitat selection. Food resources for terrestrial birds often are closely related to vegetation structure and composition. Identification of plant species important in supporting food resources may facilitate vegetation management to achieve objectives for providing bird habitat. We used fecal analysis to describe the diet of adult Wilson's Warblers (Wilsonia pusilla) that foraged in the understory of Douglas-fir (Pseudotsuga menziesii) forests in western Oregon during the breeding season. We sampled arthropods at the same sites where diet data were collected, and compared abundance and biomass of prey among seven common shrub species. Wilson's Warblers ate more caterpillars (Lepidoptera larvae), flies (Diptera), beetles (Coleoptera), and Homoptera than expected based on availability. Deciduous shrubs supported higher abundances of arthropod taxa and size classes used as prey by Wilson's Warblers than did evergreen shrubs. The development and maintenance of deciduous understory vegetation in conifer forests of the Pacific Northwest may be fundamental for conservation of food webs that support breeding Wilson's Warblers and other shrub-associated, insectivorous songbirds.

Managing Understory Vegetation for Maintaining Productivity in Black Spruce Forests: A Synthesis within a Multi-Scale Research Model

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Gilles Joanisse

2013-07-01

Full Text Available Sustainable management of boreal ecosystems involves the establishment of vigorous tree regeneration after harvest. However, two groups of understory plants influence regeneration success in eastern boreal Canada. Ericaceous shrubs are recognized to rapidly dominate susceptible boreal sites after harvest. Such dominance reduces recruitment and causes stagnant conifer growth, lasting decades on some sites. Additionally, peat accumulation due to Sphagnum growth after harvest forces the roots of regenerating conifers out of the relatively nutrient rich and warm mineral soil into the relatively nutrient poor and cool organic layer, with drastic effects on growth. Shifts from once productive black spruce forests to ericaceous heaths or paludified forests affect forest productivity and biodiversity. Under natural disturbance dynamics, fires severe enough to substantially reduce the organic layer thickness and affect ground cover species are required to establish a productive regeneration layer on such sites. We succinctly review how understory vegetation influences black spruce ecosystem dynamics in eastern boreal Canada, and present a multi-scale research model to understand, limit the loss and restore productive and diverse ecosystems in this region. Our model integrates knowledge of plant-level mechanisms in the development of silvicultural tools to sustain productivity. Fundamental knowledge is integrated at stand, landscape, regional and provincial levels to understand the distribution and dynamics of ericaceous shrubs and paludification processes and to support tactical and strategic forest management. The model can be adapted and applied to other natural resource management problems, in other biomes.

Carbon dioxide and water vapour exchange from understory species in boreal forest.

NARCIS (Netherlands)

Heijmans, M.M.P.D.; Arp, W.J.; Chapin, F.S.

2004-01-01

Although recent eddy covariance measurements in boreal forests provide CO2 and energy exchange data for the whole ecosystem, very little is known about the role of the understory vegetation. We conducted chamber flux measurements in an Alaskan black spruce forest in order to compare CO2 and water

Effect of understory management on phenological responses of eastern black walnut on an alluvial Arkansas soil

Science.gov (United States)

Black walnut (Juglans nigra L.) is commonly grown in agroforestry practices for nuts and/or timber with little knowledge of how understory herbage management might affect tree phenology. We compared black walnut plant type (variety and wild-type) for phenological response in date of budburst, leaf ...

[Understory effects on overstory trees: A review.

Science.gov (United States)

Du, Zhong; Cai, Xiao Hu; Bao, Wei Kai; Chen, Huai; Pan, Hong Li

2016-03-01

Plant-plant interactions play a key role in regulating the composition and structure of communities and ecosystems. Studies of plant-plant interactions in forest ecosystems have traditionally concentrated on either tree-tree interactions or overstory species' impacts on understory plants. The possible effects of understory species on overstory trees have received less attention. We summarized the effects of understory species on soil physiological properties, soil fauna activities, leaf litter decomposition, and ecophysiology and growth of the overstory species. Then the effects of distur-bance on understory-overstory interactions were discussed. Finally, an ecophysiology-based concept model of understory effects on overstory trees was proposed. Understory removal experiments showed that the study area, overstory species age, soil fertility and understory species could significantly affect the understory-overstory interactions.

Fuels planning: science synthesis and integration; environmental consequences fact sheet 10: The Understory Response Model

Science.gov (United States)

Steve Sutherland; Melanie Miller

2005-01-01

The Understory Response Model is a species-specific computer model that qualitatively predicts change in total species biomass for grasses, forbs, and shrubs after thinning, prescribed fire, or wildfire. The model examines the effect of fuels management on plant survivorship and reproduction. This fact sheet identifies the intended users and uses, required inputs, what...

Influence of Afforestation on the Species Diversity of the Soil Seed Bank and Understory Vegetation in the Hill-Gullied Loess Plateau, China.

Science.gov (United States)

Wang, Ning; Jiao, Juying; Jia, Yanfeng; Wang, Dongli

2017-10-24

The Chinese Loess Plateau region has long been suffering from serious soil erosion. Thus, large-scale afforestation has continued during the past decades in order to control soil erosion. Afforestation can dramatically alter nutrient cycles, affect soil-carbon storage, and change hydrology. However, it is unknown how afforestation influences species diversity of the soil seed bank and understory vegetation compared with spontaneous restoration of abandoned land. Forest land with trees planted 30 years ago, abandoned slope land restored spontaneously for 30 years, and the corresponding slopes with remnant natural vegetation were selected as sampling sites. The species richness both in the soil seed bank and vegetation was significantly higher on the afforested slope compared to the spontaneously restored abandoned land. The species similarity between the afforested slope and the remnant slope land was high both in the soil seed bank and standing vegetation compared to the abandoned land. The soil seed bank density varied from 1778 ± 187 to 3896 ± 221 seeds/m², and more than half of it was constituted by annual and biennial species, with no significant difference among sampling habitats. However, the afforested slope had higher seed density of grass and shrub/subshrubs compared to the abandoned slope. The present study indicates that in the study region, characterized by serious soil erosion, afforestation can better facilitate vegetation succession compared to spontaneously restoration of abandoned slope land.

Photosynthetic responses to understory shade and elevated carbon dioxide concentration in 4 northern hardwood tree species

International Nuclear Information System (INIS)

Sefcik, L.T.; Zak, D.R.; Ellsworth, D.S.

2006-01-01

Stimulation of photosynthesis in response to elevated carbon dioxide (CO 2 ) varies among tree species and species groups. In this study, seedling responses to elevated atmospheric carbon dioxide (CO 2 ) concentrations and solar irradiance over 2 growing seasons were investigated for shade tolerant Acer saccharum Marsh.; Fagus grandifolia J.F. Ehrh; and shade-intolerant Prunus serotina. Seedlings were exposed to a combination of elevated and ambient concentrations of CO 2 and understory shade in open-top chambers placed in a forest understory. It was observed that the elevated CO 2 treatment increased mean light-saturated net photosynthetic rates by 63 per cent in the shade-tolerant species and 67 per cent in the shade-intolerant species. When measured at the elevated CO 2 , long-term enhancement of photosynthesis was 10 per cent lower than the instantaneous enhancement observed in ambient-CO 2 -grown plants. As the growth irradiance increased, proportional enhancement due to elevated CO 2 decreased from 97 per cent for plants grown in deep shade to 47 per cent for plants grown in moderate shade. Results indicated that in nitrogen (N) limited northern temperate forests, trees grown in deep shade may display greater photosynthetic gains from a CO 2 enriched atmosphere than trees growing in more moderate shade, due to greater down-regulation. It was concluded that if elevated CO 2 levels promote the survival of shade-intolerant species in dim understory light, the future composition and dynamics of successional forest communities may be altered. 70 refs., 2 tabs., 3 figs

Influence of Afforestation on the Species Diversity of the Soil Seed Bank and Understory Vegetation in the Hill-Gullied Loess Plateau, China

Science.gov (United States)

Wang, Ning; Jiao, Juying; Jia, Yanfeng; Wang, Dongli

2017-01-01

The Chinese Loess Plateau region has long been suffering from serious soil erosion. Thus, large-scale afforestation has continued during the past decades in order to control soil erosion. Afforestation can dramatically alter nutrient cycles, affect soil-carbon storage, and change hydrology. However, it is unknown how afforestation influences species diversity of the soil seed bank and understory vegetation compared with spontaneous restoration of abandoned land. Forest land with trees planted 30 years ago, abandoned slope land restored spontaneously for 30 years, and the corresponding slopes with remnant natural vegetation were selected as sampling sites. The species richness both in the soil seed bank and vegetation was significantly higher on the afforested slope compared to the spontaneously restored abandoned land. The species similarity between the afforested slope and the remnant slope land was high both in the soil seed bank and standing vegetation compared to the abandoned land. The soil seed bank density varied from 1778 ± 187 to 3896 ± 221 seeds/m2, and more than half of it was constituted by annual and biennial species, with no significant difference among sampling habitats. However, the afforested slope had higher seed density of grass and shrub/subshrubs compared to the abandoned slope. The present study indicates that in the study region, characterized by serious soil erosion, afforestation can better facilitate vegetation succession compared to spontaneously restoration of abandoned slope land. PMID:29064405

The influence of canopy-layer composition on understory plant diversity in southern temperate forests

Directory of Open Access Journals (Sweden)

Luciana Mestre

2017-05-01

Full Text Available Background Understory plants represents the largest component of biodiversity in most forest ecosystems and plays a key role in forest functioning. Despite their importance, the influence of overstory-layer composition on understory plant diversity is relatively poorly understood within deciduous-evergreen broadleaved mixed forests. The aim of this work was to evaluate how tree overstory-layer composition influences on understory-layer diversity in three forest types (monospecific deciduous Nothofagus pumilio (Np, monospecific evergreen Nothofagus betuloides (Nb, and mixed N. pumilio-N. betuloides (M forests, comparing also between two geographical locations (coast and mountain to estimate differences at landscape level. Results We recorded 46 plant species: 4 ferns, 12 monocots, and 30 dicots. Canopy-layer composition influences the herb-layer structure and diversity in two different ways: while mixed forests have greater similarity to evergreen forests in the understory structural features, deciduous and mixed were similar in terms of the specific composition of plant assemblage. Deciduous pure stands were the most diverse, meanwhile evergreen stands were least diverse. Lack of exclusive species of mixed forest could represent a transition where evergreen and deciduous communities meet and integrate. Moreover, landscape has a major influence on the structure, diversity and richness of understory vegetation of pure and mixed forests likely associated to the magnitude and frequency of natural disturbances, where mountain forest not only had highest herb-layer diversity but also more exclusive species. Conclusions Our study suggests that mixed Nothofagus forest supports coexistence of both pure deciduous and pure evergreen understory plant species and different assemblages in coastal and mountain sites. Maintaining the mixture of canopy patch types within mixed stands will be important for conserving the natural patterns of understory plant

Diet of Wilson's warblers and distribution of arthropod prey in the understory of Douglas-fir forests

Science.gov (United States)

Hagar, Joan C.; Dugger, Kate; Starkey, Edward E.

2007-01-01

Availability of food resources is an important factor in avian habitat selection. Food resources for terrestrial birds often are closely related to vegetation structure and composition. Identification of plant species important in supporting food resources may facilitate vegetation management to achieve objectives for providing bird habitat. We used fecal analysis to describe the diet of adult Wilson's Warblers (Wilsonia pusilla) that foraged in the understory of Douglas-fir (Pseudotsuga menziesii) forests in western Oregon during the breeding season. We sampled arthropods at the same sites where diet data were collected, and compared abundance and biomass of prey among seven common shrub species. Wilson's Warblers ate more caterpillars (Lepidoptera larvae), flies (Diptera), beetles (Coleoptera), and Homoptera than expected based on availability. Deciduous shrubs supported higher abundances of arthropod taxa and size classes used as prey by Wilson's Warblers than did evergreen shrubs. The development and maintenance of deciduous understory vegetation in conifer forests of the Pacific Northwest may be fundamental for conservation of food webs that support breeding Wilson's Warblers and other shrub-associated, insectivorous songbirds.

Radionuclide concentrations in vegetation at the Los Alamos National Laboratory in 1998

International Nuclear Information System (INIS)

Gonzales, G.J.; Fresquez, P.R.; Mullen, M.A.; Naranjo, L. Jr.

2000-01-01

This report summarizes and evaluates the concentrations of 3 H, 137 Cs, 238 Pu, 239,240 Pu, 241 Am, 90 Sr, and total U in understory and overstory vegetation collected from Los Alamos National Laboratory (LANL), its perimeter, and regional background areas in 1998. Comparisons to conservative toxicity reference value safe limits were also made. The arithmetic mean LANL radionuclide concentrations in understory were 501 pCi L -1 for 3 H, 0.581 pCi ash g -1 for 137 Cs, 0.001 pCi ash g -1 for 238 Pu, 0.008 pCi ash g -1 for 239,240 Pu, 0.007 pCi ash g -1 for 241 Am, 1.46 pCi ash g -1 for 90 Sr, and 0.233 microg ash g -1 for total uranium. The mean LANL radionuclide concentrations in overstory were 463 pCi L -1 for 3 H, 1.51 pCi ash g -1 for 137 Cs, 0.0004 pCi ash g -1 238 Pu, 0.008 pCi ash g -1 for 239,240 Pu, 0.014 pCi ash g -1 for 241 Am, 1.97 pCi ash g -1 for 90 Sr, and 0.388 microg ash g -1 for total uranium. Concentrations of radionuclides and total U in both understory and overstory vegetation at LANL generally were not statistically higher than in perimeter and regional background vegetation (α = 0.05). The exceptions were LANL 3 H > perimeter 3 H (understory) and LANL 3 H background 3 H (overstory). All maximum radionuclide concentrations were lower than toxicity reference values. With the exception of total U, the relationship between contaminant concentration in soil vs. vegetation was insignificant (α = 0.05). Generally, as the concentration of total U in soil decreased, the concentration in vegetation increased. This held true for both understory and overstory and regardless of whether data were separated by general location (LANL, perimeter, and background) or not. There was no apparent relationship between contaminant concentrations in understory vs. overstory

Radionuclide concentrations in soils and vegetation at radioactive-waste disposal Area G during the 1996 growing season. Progress report

International Nuclear Information System (INIS)

Fresquez, P.R.; Vold, E.L.; Naranjo, L. Jr.

1997-07-01

Soil and overstory and understory vegetation (washed and unwashed) collected at eight locations within and around Area G--a low-level radioactive solid-waste disposal facility at Los Alamos National laboratory--were analyzed for 3 H, 90 Sr, 238 Pu, 239 Pu, 137 Cs, 234 U, 235 U, 238 U, tot U, 228 Ac, 214 Bi, 60 Co, 40 K, 54 Mn, 22 Na, 214 Pb, and 208 Tl. Also, heavy metals (Ag, As, Ba, Be, Cd, Cr, Hg, Ni, Pb, Sb, Se, and Tl) in soil and vegetation were determined. In general, most radionuclide concentrations, with the exception of 3 H and 239 Pu, in soils and washed and unwashed overstory and understory vegetation collected from within and around Area G were within upper limit background concentrations. Tritium was detected as high as 14,744 pCi mL -1 in understory vegetation collected from transuranic (TRU) waste pad number-sign 4, and the TRU waste pad area contained the highest levels of 239 Pu in soils and in understory vegetation as compared to other areas at Area G

Understory Vegetative Diversity of Post-Thinned Pine Plantations Treated with Fertilizer, Fire and Herbicide in East Texas

International Nuclear Information System (INIS)

Oswald, B.P.; Williams, H.M.; Farrish, K.W.; Ott, B.; Van Kley, J.E.

2009-01-01

This study assessed biodiversity in the understory of two pine plantations where different management tools (fertilizer, prescribed burning, and herbicide application) were utilized. During three growing seasons, species, percent cover, and number of individuals, and physical characteristics were recorded. Responses to treatment were examined based on comparison of species richness, evenness, diversity, and importance. Two years after treatment, fertilized plots showed a decline in species richness, evenness, and diversity. Prescribed burning and herbicide treatments increased species richness but decreased species evenness, resulting in no change in diversity index. Herbicide treatment reduced the importance of dominant shrubs and increased the importance of disturbance-adapted species.

Understory Vegetative Diversity of Post-Thinned Pine Plantations Treated with Fertilizer, Fire and Herbicide in East Texas

Directory of Open Access Journals (Sweden)

Brian P. Oswald

2009-01-01

Full Text Available This study assessed biodiversity in the understory of two pine plantations where different management tools (fertilizer, prescribed burning, and herbicide application were utilized. During three growing seasons, species, percent cover, and number of individuals, and physical characteristics were recorded. Responses to treatment were examined based on comparison of species richness, evenness, diversity, and importance. Two years after treatment, fertilized plots showed a decline in species richness, evenness, and diversity. Prescribed burning and herbicide treatments increased species richness but decreased species evenness, resulting in no change in diversity index. Herbicide treatment reduced the importance of dominant shrubs and increased the importance of disturbance-adapted species.

Effects of understory vegetation and litter on plant nitrogen (N, phosphorus (P, N:P ratio and their relationships with growth rate of indigenous seedlings in subtropical plantations.

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Jun Wang

Full Text Available Establishing seedlings in subtropical plantations is very important for forest health, succession and management. Information on seedling nutrient concentrations is essential for both the selection of suitable indigenous tree species to accelerate succession of the established plantation and sustainable forest management. In this study, we investigated the concentrations of nitrogen ([N], phosphorus ([P], and N:P ratio in leaves, stems and roots of seedlings of three indigenous tree species (Castanopsis chinensis, Michelia chapensis and Psychotria rubra transplanted with removing or retaining understory vegetation and litter at two typical subtropical forest plantations (Eucalyptus plantation and native species plantation. We also measured the relative growth rate (RGR of seedling height, and developed the relationships between RGR and leaf [N], [P] and N:P ratio. Results showed that treatments of understory vegetation and associated litter (i.e. removal or retained generally had no significant effects on leaf [N], [P], N:P ratio and RGR of the transplanted tree seedlings for the experimental period. But among different species, there were significant differences in nutrient concentrations. M. chapensis and P. rubra had higher [N] and [P] compared to C. chinensis. [N] and [P] also varied among different plant tissues with much higher values in leaves than in roots for all indigenous species. RGR of indigenous tree seedlings was mostly positively correlated with leaf [N] and [P], but negatively correlated with leaf N:P ratio. Considering the low [P] and high N:P ratio observed in the introduced indigenous tree seedlings, we propose that the current experimental plantations might be P limited for plant growth.

Radionuclide concentrations in/on vegetation at radioactive-waste disposal Area G during the 1995 growing season. Progress report

International Nuclear Information System (INIS)

Fresquez, P.R.; Vold, E.L.; Naranjo, L. Jr.

1996-01-01

Overstory (pinon pine) and understory (grass and forb) vegetation were collected within and around selected points at Area G--a low- level radioactive solid-waste disposal facility at Los Alamos National Laboratory--for the analysis of tritium ( 3 H), strontium ( 90 Sr), plutonium ( 238 Pu and 239 Pu), cesium ( 137 Cs), and total uranium. Also, heavy metals (Ag, As, Ba, Be, Cd, Cr, Hg, Ni, Pb, Sb, Se, and Tl) in/on vegetation were determined. In general, most (unwashed) vegetation collected within and around Area G contained 3 H, uranium, 238 Pu, and 239 Pu in higher concentrations than vegetation collected from background areas. Tritium, in particular, was detected as high as 7300 pCi mL -1 in understory vegetation collected from the west side of the transuranic (TRU) pads. The south and west ends of the tritium shaft field also contained elevated levels of 3 H in overstory, and especially in understory vegetation, as compared to background; this suggests that 3 H may be migrating from this waste repository through surface and subsurface pathways. Also, understory vegetation collected north of the TRU pads (adjacent to the fence line of Area G) contained the highest values of 238 Pu and 239 Pu as compared to background, and may be a result of surface holding, storage, and/or disposal activities

Short-term light and leaf photosynthetic dynamics affect estimates of daily understory photosynthesis in four tree species.

Science.gov (United States)

Naumburg, Elke; Ellsworth, David S

2002-04-01

Instantaneous measurements of photosynthesis are often implicitly or explicitly scaled to longer time frames to provide an understanding of plant performance in a given environment. For plants growing in a forest understory, results from photosynthetic light response curves in conjunction with diurnal light data are frequently extrapolated to daily photosynthesis (A(day)), ignoring dynamic photosynthetic responses to light. In this study, we evaluated the importance of two factors on A(day) estimates: dynamic physiological responses to photosynthetic photon flux density (PPFD); and time-resolution of the PPFD data used for modeling. We used a dynamic photosynthesis model to investigate how these factors interact with species-specific photosynthetic traits, forest type, and sky conditions to affect the accuracy of A(day) predictions. Increasing time-averaging of PPFD significantly increased the relative overestimation of A(day) similarly for all study species because of the nonlinear response of photosynthesis to PPFD (15% with 5-min PPFD means). Depending on the light environment characteristics and species-specific dynamic responses to PPFD, understory tree A(day) can be overestimated by 6-42% for the study species by ignoring these dynamics. Although these overestimates decrease under cloudy conditions where direct sunlight and consequently understory sunfleck radiation is reduced, they are still significant. Within a species, overestimation of A(day) as a result of ignoring dynamic responses was highly dependent on daily sunfleck PPFD and the frequency and irradiance of sunflecks. Overall, large overestimates of A(day) in understory trees may cause misleading inferences concerning species growth and competition in forest understories with sunlight. We conclude that comparisons of A(day) among co-occurring understory species in deep shade will be enhanced by consideration of sunflecks by using high-resolution PPFD data and understanding the physiological

Understory succession in post-agricultural oak plantations

DEFF Research Database (Denmark)

Brunet, Jörg; Valtinat, Karin; Mayr, Marian Lajos

2011-01-01

The herbaceous understory forms the richest stratum in temperate broadleaved forests in terms of plant diversity. Understanding the process of understory succession is thus of critical importance for the development of management guidelines for biodiversity restoration in post-agricultural planta......The herbaceous understory forms the richest stratum in temperate broadleaved forests in terms of plant diversity. Understanding the process of understory succession is thus of critical importance for the development of management guidelines for biodiversity restoration in post...... forested stands, which maintained differences in species composition. The development of a shrub layer seemed to imply a competitive advantage for forest specialists compared to generalist species. For successful recovery of a rich understory, we suggest that post-arable plantations should be established......, and woody species. The group of forest specialists may approach the richness of continuously forested sites after 60-80 years in non-fragmented plantations, but many forest species were sensitive to habitat fragmentation. Open-land species richness decreased during succession, while the richness of woody...

Responses of Soil Organic Carbon to Long-Term Understory Removal in Subtropical Cinnamomum camphora Stands

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Yacong Wu

2014-01-01

Full Text Available We conducted a study on a 48-year-old Cinnamomum camphora plantation in the subtropics of China, by removing understory gradually and then comparing this treatment with a control (undisturbed. This study analyzed the content and storage soil organic carbon (SOC in a soil depth of 0–60 cm. The results showed that SOC content was lower in understory removal (UR treatment, with a decrease range from 5% to 34%, and a decline of 10.16 g·kg−1 and 8.58 g·kg−1 was noticed in 0–10 cm and 10–20 cm layers, respectively, with significant differences (P<0.05. Carbon storage was reduced in UR, ranging from 2% to 43%, with a particular drastic decline of 15.39 t·hm−2 and 11.58 t·hm−2 in 0–10 cm (P<0.01 and 10–20 cm (P<0.01 layers, respectively. Content of SOC had an extremely significant (P<0.01 correlation with soil nutrients in the two stands, and the correlation coefficients of CK were higher than those of UR. Our data showed that the presence of understory favored the accumulation of soil organic carbon to a large extent. Therefore, long-term practice of understory removal weakens the function of forest ecosystem as a carbon sink.

Understory fern community structure, growth and spore production responses to a large-scale hurricane experiment in a Puerto Rico rainforest

Science.gov (United States)

Joanne M. Sharpe; Aaron B. Shiels

2014-01-01

Ferns are abundant in most rainforest understories yet their responses to hurricanes have not been well studied. Fern community structure, growth and spore production were monitored for two years before and five years after a large-scale experiment that simulated two key components of severe hurricane disturbance: canopy openness and debris deposition. The canopy was...

BOREAS TE-9 In Situ Understory Spectral Reflectance Within the NSA

Science.gov (United States)

Hall, Forrest G. (Editor); Curd, Shelaine (Editor); Supronowicz, Jan; Edwards, Geoffrey; Viau, Alain; Thomson, Keith

2000-01-01

The Boreal Ecosystem-Atmospheric Study (BOREAS) TE-9 (Terrestrial Ecology) team collected several data sets related to chemical and photosynthetic properties of leaves in boreal forest tree species. Spectral reflection coefficients of the forest understory at the ground level, in three boreal forest sites of Northern Manitoba (56 N latitude and 98 W longitude), were obtained and analyzed in 1994. In particular, angular variation of the reflection coefficients in the old jack pine and young jack pine forests, as well as nadir reflection coefficient in the young aspen forest, were investigated. The complexity of understory composition and the light patterns limited quantitative conclusions; however, a number of interesting trends in the behavior of the measured values can be inferred. In particular, the unique spectral profiles of lichens show very strongly in the old jack pine understory, yet are definitely less conspicuous for young jack pine, and virtually absent in the aspen forest. The angular variation of the reflection coefficient by the young pine understory seems to be significantly toned down by fine-structured branches and their shadows. Our study also indicates how difficult the ground reflection coefficient problem in a forest is, compared to certain previously investigated areas that have a more uniform appearance, such as prairie grassland, bare soil, or agricultural crops. This is due to several factors, generally typical of a forest environment, that may influence the overall understory reflection coefficient, including: (1) a strong diversity of the forest floor due to the presence of dead tree trunks, holes in the ground, patches of different types of vegetation or litter, etc.; (2) pronounced 3-D structures at the ground level, such as shrubs, bushes, and young trees; and (3) an irregular shadow mosaic, which not only varies with the time of the day, causing intensity variations, but likely also effectively modifies the spectrum of the

Understory plant diversity in mixed and pure plantations of jatropha curcas vs. native vegetation in the lower-middle reaches of the lancang-meikong river watershed, china

International Nuclear Information System (INIS)

Ou, G.L.; Ma, H.C.; Tang, J.R.

2015-01-01

22 plots at the Xiaoheijiang base, located in the lower-middle reaches of the Lancang-Meikong River in China, were investigated to analyze the understory biodiversity of Jatropha curcas plantations. Two kinds of mixed modes of J. curcas (mixed plantation with Macadamia integrifolia and mixed plantation with shrub species) and a pure plantation of J. curcas were planted, while the native vegetation served as a control. The plots were distributed along the gradients of forest management, succession and elevation by CCA analysis. Species richness was not significantly different for the different types of plantation, but the evenness of species could be affected, especially for the total community and the understory by planting J. curcas. The diversity and evenness indices of species were affected for the mixed plantation with different proportions of M. integrifolia, especially for the shrub layer, the Shannon diversity index and Pilou evenness index showed significant differences. And for the different mixed shrub species, only the Shannon diversity index and Pilou evenness index were significantly different. Finally, from the perspective of biological diversity, J.curcas plantation with shrub species would be a recommended planting model for ecological restoration in a dry-hot valley area, while J. curcas plantation with M. integrifolia would be an effective planting model to balance crop yield and food security. (author)

Foliar moisture content of Pacific Northwest vegetation and its relation to wildland fire behavior.

Science.gov (United States)

James K. Agee; Clinton S. Wright; Nathan Williamson; Mark H. Huff

2002-01-01

Fotiar moisture was monitored for five conifers and associated understory vegetation in Pacific Northwest forests. Decline in foliar moisture of new foliage occurred over the dry season, while less variation was evident in older foliage. Late season foliar moisture ranged from 130 to 170%. In riparian-upland comparisons, largest differences were found for understory...

Growth responses of trees and understory plants to nitrogen fertilization in a subtropical forest in China

Science.gov (United States)

Tian, Di; Li, Peng; Fang, Wenjing; Xu, Jun; Luo, Yongkai; Yan, Zhengbing; Zhu, Biao; Wang, Jingjing; Xu, Xiaoniu; Fang, Jingyun

2017-07-01

Reactive nitrogen (N) increase in the biosphere has been a noteworthy aspect of global change, producing considerable ecological effects on the functioning and dynamics of the terrestrial ecosystems. A number of observational studies have explored responses of plants to experimentally simulated N enrichment in boreal and temperate forests. Here we investigate how the dominant trees and different understory plants respond to experimental N enrichment in a subtropical forest in China. We conducted a 3.4-year N fertilization experiment in an old-aged subtropical evergreen broad-leaved forest in eastern China with three treatment levels applied to nine 20 m × 20 m plots and replicated in three blocks. We divided the plants into trees, saplings, shrubs (including tree seedlings), and ground-cover plants (ferns) according to the growth forms, and then measured the absolute and relative basal area increments of trees and saplings and the aboveground biomass of understory shrubs and ferns. We further grouped individuals of the dominant tree species, Castanopsis eyrei, into three size classes to investigate their respective growth responses to the N fertilization. Our results showed that the plot-averaged absolute and relative growth rates of basal area and aboveground biomass of trees were not affected by N fertilization. Across the individuals of C. eyrei, the small trees with a DBH (diameter at breast height) of 5-10 cm declined by 66.4 and 59.5 %, respectively, in N50 (50 kg N ha-1 yr-1) and N100 fertilized plots (100 kg N ha-1 yr-1), while the growth of median and large trees with a DBH of > 10 cm did not significantly change with the N fertilization. The growth rate of small trees, saplings, and the aboveground biomass of understory shrubs and ground-cover ferns decreased significantly in the N-fertilized plots. Our findings suggested that N might not be a limiting nutrient in this mature subtropical forest, and that the limitation of other nutrients in the forest

Growth responses of trees and understory plants to nitrogen fertilization in a subtropical forest in China

Directory of Open Access Journals (Sweden)

D. Tian

2017-07-01

Full Text Available Reactive nitrogen (N increase in the biosphere has been a noteworthy aspect of global change, producing considerable ecological effects on the functioning and dynamics of the terrestrial ecosystems. A number of observational studies have explored responses of plants to experimentally simulated N enrichment in boreal and temperate forests. Here we investigate how the dominant trees and different understory plants respond to experimental N enrichment in a subtropical forest in China. We conducted a 3.4-year N fertilization experiment in an old-aged subtropical evergreen broad-leaved forest in eastern China with three treatment levels applied to nine 20 m  ×  20 m plots and replicated in three blocks. We divided the plants into trees, saplings, shrubs (including tree seedlings, and ground-cover plants (ferns according to the growth forms, and then measured the absolute and relative basal area increments of trees and saplings and the aboveground biomass of understory shrubs and ferns. We further grouped individuals of the dominant tree species, Castanopsis eyrei, into three size classes to investigate their respective growth responses to the N fertilization. Our results showed that the plot-averaged absolute and relative growth rates of basal area and aboveground biomass of trees were not affected by N fertilization. Across the individuals of C. eyrei, the small trees with a DBH (diameter at breast height of 5–10 cm declined by 66.4 and 59.5 %, respectively, in N50 (50 kg N ha−1 yr−1 and N100 fertilized plots (100 kg N ha−1 yr−1, while the growth of median and large trees with a DBH of  >  10 cm did not significantly change with the N fertilization. The growth rate of small trees, saplings, and the aboveground biomass of understory shrubs and ground-cover ferns decreased significantly in the N-fertilized plots. Our findings suggested that N might not be a limiting nutrient in this mature subtropical

Projecting avian responses to landscape managment along the middle RIO GRANDE, New Mexico

Science.gov (United States)

Lack of flooding due to river impoundments on the middle Rio Grande has contributed to the spread of exotic vegetation with dense understory fuel loads. Restoration has focused on understory vegetation thinning but it is unclear how these actions impact bird populations. We quantified densities of ...

Seasonal moisture fluctuations four species of pocosin vegetation

Science.gov (United States)

George W. Wendel; Theodore G. Storey

1962-01-01

During the most severe burning conditions practically all of the living understory vegetation on pocosins may be consumed by fire (9). Even under less severe conditions leaves and branch tips are readily consumed. Whether the moisture content in the living vegetation is high, as it is in the spring, or low, as in the winter, exerts a strong influence on fuel...

Variation in herbaceous vegetation and soil moisture under treated and untreated oneseed juniper trees

Science.gov (United States)

Hector Ramirez; Alexander Fernald; Andres Cibils; Michelle Morris; Shad Cox; Michael Rubio

2008-01-01

Clearing oneseed juniper (Juniperus monosperma) may make more water available for aquifer recharge or herbaceous vegetation growth, but the effects of tree treatment on soil moisture dynamics are not fully understood. This study investigated juniper treatment effects on understory herbaceous vegetation concurrently with soil moisture dynamics using vegetation sampling...

Radionuclide Concentrations in Soils and Vegetation at Low-Level Radioactive Waste Disposal Area G during the 1997 Growing Season

Energy Technology Data Exchange (ETDEWEB)

L. Naranjo, Jr.; P. R. Fresquez; R. J. Wechsler

1998-08-01

Soil and overstory and understory vegetation (washed and unwashed) collected at eight locations within and around Area G-a low-level radioactive solid-waste disposal facility at Los Alamos National Laboratory-were analyzed for 3H, 238Pu, 239Pu, 137CS, 234U, 235U, 228AC, Be, 214Bi, 60Co, 40& 54Mn, 22Na, 214Pb and 208Tl. In general, most radionuclide concentrations, with the exception of 3Ef and ~9Pu, in soils and overstory and understory vegetation collected from within and around Area G were within upper (95'%) level background concentrations. Although 3H concentrations in vegetation from most sites were significantly higher than background (>2 pCi mL-l), concentrations decreased markedly in comparison to last year's results. The highest `H concentration in vegetation was detected from a juniper tree that was growing over tritium shaft /+150; it contained 530,000 pCi 3H mL-l. Also, as in the pas~ the transuranic waste pad area contained the highest levels of 239Pu in soils and in understory vegetation as compared to other areas at Area G.

Infrared heater system for warming tropical forest understory plants and soils

Science.gov (United States)

Bruce A. Kimball; Aura M. Alonso-Rodríguez; Molly A. Cavaleri; Sasha C. Reed; Grizelle González; Tana E. Wood

2018-01-01

The response of tropical forests to global warming is one of the largest uncertainties in predicting the future carbon balance of Earth. To determine the likely effects of elevated temperatures on tropical forest understory plants and soils, as well as other ecosystems, an infrared (IR) heater system was developed to provide in situ warming for the Tropical Responses...

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...

Understory Plant Community Composition Is Associated with Fine-Scale Above- and Below-Ground Resource Heterogeneity in Mature Lodgepole Pine (Pinus contorta) Forests

Science.gov (United States)

McIntosh, Anne C. S.; Macdonald, S. Ellen; Quideau, Sylvie A.

2016-01-01

Understory plant communities play critical ecological roles in forest ecosystems. Both above- and below-ground ecosystem properties and processes influence these communities but relatively little is known about such effects at fine (i.e., one to several meters within-stand) scales, particularly for forests in which the canopy is dominated by a single species. An improved understanding of these effects is critical for understanding how understory biodiversity is regulated in such forests and for anticipating impacts of changing disturbance regimes. Our primary objective was to examine the patterns of fine-scale variation in understory plant communities and their relationships to above- and below-ground resource and environmental heterogeneity within mature lodgepole pine forests. We assessed composition and diversity of understory vegetation in relation to heterogeneity of both the above-ground (canopy tree density, canopy and tall shrub basal area and cover, downed wood biomass, litter cover) and below-ground (soil nutrient availability, decomposition, forest floor thickness, pH, and phospholipid fatty acids (PLFAs) and multiple carbon-source substrate-induced respiration (MSIR) of the forest floor microbial community) environment. There was notable variation in fine-scale plant community composition; cluster and indicator species analyses of the 24 most commonly occurring understory species distinguished four assemblages, one for which a pioneer forb species had the highest cover levels, and three others that were characterized by different bryophyte species having the highest cover. Constrained ordination (distance-based redundancy analysis) showed that two above-ground (mean tree diameter, litter cover) and eight below-ground (forest floor pH, plant available boron, microbial community composition and function as indicated by MSIR and PLFAs) properties were associated with variation in understory plant community composition. These results provide novel insights

Understory Plant Community Composition Is Associated with Fine-Scale Above- and Below-Ground Resource Heterogeneity in Mature Lodgepole Pine (Pinus contorta Forests.

Directory of Open Access Journals (Sweden)

Anne C S McIntosh

Full Text Available Understory plant communities play critical ecological roles in forest ecosystems. Both above- and below-ground ecosystem properties and processes influence these communities but relatively little is known about such effects at fine (i.e., one to several meters within-stand scales, particularly for forests in which the canopy is dominated by a single species. An improved understanding of these effects is critical for understanding how understory biodiversity is regulated in such forests and for anticipating impacts of changing disturbance regimes. Our primary objective was to examine the patterns of fine-scale variation in understory plant communities and their relationships to above- and below-ground resource and environmental heterogeneity within mature lodgepole pine forests. We assessed composition and diversity of understory vegetation in relation to heterogeneity of both the above-ground (canopy tree density, canopy and tall shrub basal area and cover, downed wood biomass, litter cover and below-ground (soil nutrient availability, decomposition, forest floor thickness, pH, and phospholipid fatty acids (PLFAs and multiple carbon-source substrate-induced respiration (MSIR of the forest floor microbial community environment. There was notable variation in fine-scale plant community composition; cluster and indicator species analyses of the 24 most commonly occurring understory species distinguished four assemblages, one for which a pioneer forb species had the highest cover levels, and three others that were characterized by different bryophyte species having the highest cover. Constrained ordination (distance-based redundancy analysis showed that two above-ground (mean tree diameter, litter cover and eight below-ground (forest floor pH, plant available boron, microbial community composition and function as indicated by MSIR and PLFAs properties were associated with variation in understory plant community composition. These results provide

Understory Plant Community Composition Is Associated with Fine-Scale Above- and Below-Ground Resource Heterogeneity in Mature Lodgepole Pine (Pinus contorta) Forests.

Science.gov (United States)

McIntosh, Anne C S; Macdonald, S Ellen; Quideau, Sylvie A

2016-01-01

Understory plant communities play critical ecological roles in forest ecosystems. Both above- and below-ground ecosystem properties and processes influence these communities but relatively little is known about such effects at fine (i.e., one to several meters within-stand) scales, particularly for forests in which the canopy is dominated by a single species. An improved understanding of these effects is critical for understanding how understory biodiversity is regulated in such forests and for anticipating impacts of changing disturbance regimes. Our primary objective was to examine the patterns of fine-scale variation in understory plant communities and their relationships to above- and below-ground resource and environmental heterogeneity within mature lodgepole pine forests. We assessed composition and diversity of understory vegetation in relation to heterogeneity of both the above-ground (canopy tree density, canopy and tall shrub basal area and cover, downed wood biomass, litter cover) and below-ground (soil nutrient availability, decomposition, forest floor thickness, pH, and phospholipid fatty acids (PLFAs) and multiple carbon-source substrate-induced respiration (MSIR) of the forest floor microbial community) environment. There was notable variation in fine-scale plant community composition; cluster and indicator species analyses of the 24 most commonly occurring understory species distinguished four assemblages, one for which a pioneer forb species had the highest cover levels, and three others that were characterized by different bryophyte species having the highest cover. Constrained ordination (distance-based redundancy analysis) showed that two above-ground (mean tree diameter, litter cover) and eight below-ground (forest floor pH, plant available boron, microbial community composition and function as indicated by MSIR and PLFAs) properties were associated with variation in understory plant community composition. These results provide novel insights

Radionuclide concentrations in vegetation at radioactive-waste disposal Area G during the 1994 growing season

International Nuclear Information System (INIS)

Fresquez, P.R.; Biggs, J.B.; Bennett, K.D.

1995-01-01

Overstory (pinon pine) and understory (grass and forb) vegetation samples were collected within and around selected points at Area G-a low-level radioactive solid-waste disposal facility at Los Alamos National Laboratory-for the analysis of tritium ( 3 H), strontium ( 90 Sr), plutonium ( 238 Pu and 239 Pu), cesium ( 137 Cs), americium ( 241 Am), and total uranium. In general, most vegetation samples collected within and around Area G contained radionuclide levels in higher concentrations than vegetation collected from background areas. Tritium, in particular, was detected as high as 5,800 pCi/mL in overstory vegetation collected outside the fence just west of the tritium shafts; this suggests that tritium is migrating from this waste repository through subsurface pathways. Also, understory vegetation collected north of the transuranic (TRU) pads (outside the fence of Area G) contained the highest values of 90 Sr, 238 Pu, 239 Pu, 137 Cs, and 241 Am, and may be a result of surface holding, storage, or disposal activities

Vegetation response to the 2016-2017 extreme Sierra Nevada snowfall event using multitemporal terrestrial laser scanning: initial results

Science.gov (United States)

Greenberg, J. A.; Hou, Z.; Ramirez, C.; Hart, R.; Marchi, N.; Parra, A. S.; Gutierrez, B.; Tompkins, R.; Harpold, A.; Sullivan, B. W.; Weisberg, P.

2017-12-01

The Sierra Nevada Mountains experienced record-breaking snowfall during the 2016-2017 winter after a prolonged period of drought. We hypothesized that at lower elevations, the increased snowmelt would result in a significant increase in biomass across vegetation strata, but at higher elevations, the snowpack would result in a diminished growing season, and yield a suppression of growth rates particularly in the understory vegetation. To test these hypotheses, we sampled sites across the Plumas National Forest and Lake Tahoe Basin using a terrestrial laser scanner (TLS) in the early growing season, and then rescanned these sites in the late growing season. Herein, we present initial, early results from this analysis, focusing on the biomass and height changes in trees.

Diversity patterns of ground beetles and understory vegetation in mature, secondary, and plantation forest regions of temperate northern China

NARCIS (Netherlands)

Zou, Yi; Sang, Weiguo; Wang, Shunzhong; Warren-Thomas, Eleanor; Liu, Yunhui; Yu, Zhenrong; Wang, Changliu; Axmacher, Jan Christoph

2015-01-01

Plantation and secondary forests form increasingly important components of the global forest cover, but our current knowledge about their potential contribution to biodiversity conservation is limited. We surveyed understory plant and carabid species assemblages at three distinct regions in

A Passive Microwave L-Band Boreal Forest Freeze/Thaw and Vegetation Phenology Study

Science.gov (United States)

Roy, A.; Sonnentag, O.; Pappas, C.; Mavrovic, A.; Royer, A.; Berg, A. A.; Rowlandson, T. L.; Lemay, J.; Helgason, W.; Barr, A.; Black, T. A.; Derksen, C.; Toose, P.

2016-12-01

The boreal forest is the second largest land biome in the world and thus plays a major role in the global and regional climate systems. The extent, timing and duration of seasonal freeze/thaw (F/T) state influences vegetation developmental stages (phenology) and, consequently, constitute an important control on how boreal forest ecosystems exchange carbon, water and energy with the atmosphere. The effective retrieval of seasonal F/T state from L-Band radiometry was demonstrated using satellite mission. However, disentangling the seasonally differing contributions from forest overstory and understory vegetation, and the soil surface to the satellite signal remains challenging. Here we present initial results from a radiometer field campaign to improve our understanding of the L-Band derived boreal forest F/T signal and vegetation phenology. Two L-Band surface-based radiometers (SBR) are installed on a micrometeorological tower at the Southern Old Black Spruce site in central Saskatchewan over the 2016-2017 F/T season. One radiometer unit is installed on the flux tower so it views forest including all overstory and understory vegetation and the moss-covered ground surface. A second radiometer unit is installed within the boreal forest overstory, viewing the understory and the ground surface. The objectives of our study are (i) to disentangle the L-Band F/T signal contribution of boreal forest overstory from the understory and ground surface, (ii) to link the L-Band F/T signal to related boreal forest structural and functional characteristics, and (iii) to investigate the use of the L-Band signal to characterize boreal forest carbon, water and energy fluxes. The SBR observations above and within the forest canopy are used to retrieve the transmissivity (γ) and the scattering albedo (ω), two parameters that describe the emission of the forest canopy though the F/T season. These two forest parameters are compared with boreal forest structural and functional

Vegetation assessment of forests of Pagan Island, Commonwealth of the Northern Mariana Islands

Science.gov (United States)

Pratt, Linda W.

2011-01-01

As part of the Marianas Expedition Wildlife Surveys-2010, the forest vegetation of the island of Pagan, Commonwealth of the Northern Mariana Islands (CNMI), was sampled with a series of systematic plots along 13 transects established for monitoring forest bird populations. Shrubland and grassland were also sampled in the northern half of the island. Data collected were woody plant density, tree diameter at breast height, woody plant density in height classes below 2 m, and ground cover measured with the point-intercept method. Coconut forests (Cocos nucifera) were generally found to have low native tree diversity, little regeneration of trees and shrubs in the forest understory, and little live ground cover. The sole exception was a coconut-dominated forest of the northeast side of the island that exhibited high native tree diversity and a large number of young native trees in the understory. Ironwood (Casuarina equisetifolia) forests on the northern half of the island were nearly monocultures with almost no trees other than ironwood in vegetation plots, few woody plants in the understory, and low ground cover dominated by native ferns. Mixed native forests of both northern and southern sections of the island had a diversity of native tree species in both the canopy and the sparse understory. Ground cover of native forests in the north had a mix of native and alien species, but that of the southern half of the island was dominated by native ferns and woody plants.

Can the Understory Affect the Hymenoptera Parasitoids in a Eucalyptus Plantation?

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Onice Teresinha Dall'Oglio

Full Text Available The understory in forest plantations can increase richness and diversity of natural enemies due to greater plant species richness. The objective of this study was to test the hypothesis that the presence of the understory and climatic season in the region (wet or dry can increase the richness and abundance of Hymenoptera parasitoids in Eucalyptus plantations, in the municipality of Belo Oriente, Minas Gerais State, Brazil. In each eucalyptus cultivation (five areas of cultivation ten Malaise traps were installed, five with the understory and five without it. A total of 9,639 individuals from 30 families of the Hymenoptera parasitoids were collected, with Mymaridae, Scelionidae, Encyrtidae and Braconidae being the most collected ones with 4,934, 1,212, 619 and 612 individuals, respectively. The eucalyptus stands with and without the understory showed percentage of individuals 45.65% and 54.35% collected, respectively. The understory did not represent a positive effect on the overall abundance of the individuals Hymenoptera in the E. grandis stands, but rather exerted a positive effect on the specific families of the parasitoids of this order.

Can the Understory Affect the Hymenoptera Parasitoids in a Eucalyptus Plantation?

Science.gov (United States)

Dall’Oglio, Onice Teresinha; Ribeiro, Rafael Coelho; Ramalho, Francisco de Souza; Fernandes, Flávio Lemes; Wilcken, Carlos Frederico; de Assis Júnior, Sebastião Lourenço; Rueda, Rosa Angélica Plata; Serrão, José Eduardo; Zanuncio, José Cola

2016-01-01

The understory in forest plantations can increase richness and diversity of natural enemies due to greater plant species richness. The objective of this study was to test the hypothesis that the presence of the understory and climatic season in the region (wet or dry) can increase the richness and abundance of Hymenoptera parasitoids in Eucalyptus plantations, in the municipality of Belo Oriente, Minas Gerais State, Brazil. In each eucalyptus cultivation (five areas of cultivation) ten Malaise traps were installed, five with the understory and five without it. A total of 9,639 individuals from 30 families of the Hymenoptera parasitoids were collected, with Mymaridae, Scelionidae, Encyrtidae and Braconidae being the most collected ones with 4,934, 1,212, 619 and 612 individuals, respectively. The eucalyptus stands with and without the understory showed percentage of individuals 45.65% and 54.35% collected, respectively. The understory did not represent a positive effect on the overall abundance of the individuals Hymenoptera in the E. grandis stands, but rather exerted a positive effect on the specific families of the parasitoids of this order. PMID:26954578

A Simple Method for Retrieving Understory NDVI in Sparse Needleleaf Forests in Alaska Using MODIS BRDF Data

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Wei Yang

2014-12-01

Full Text Available Global products of leaf area index (LAI usually show large uncertainties in sparsely vegetated areas because the understory contribution is not negligible in reflectance modeling for the case of low to intermediate canopy cover. Therefore, many efforts have been made to include understory properties in LAI estimation algorithms. Compared with the conventional data bank method, estimation of forest understory properties from satellite data is superior in studies at a global or continental scale over long periods. However, implementation of the current remote sensing method based on multi-angular observations is complicated. As an alternative, a simple method to retrieve understory NDVI (NDVIu for sparse boreal forests was proposed in this study. The method is based on the fact that the bidirectional variation in NDVIu is smaller than that in canopy-level NDVI. To retrieve NDVIu for a certain pixel, linear extrapolation was applied using pixels within a 5 × 5 target-pixel-centered window. The NDVI values were reconstructed from the MODIS BRDF data corresponding to eight different solar-view angles. NDVIu was estimated as the average of the NDVI values corresponding to the position in which the stand NDVI had the smallest angular variation. Validation by a noise-free simulation data set yielded high agreement between estimated and true NDVIu, with R2 and RMSE of 0.99 and 0.03, respectively. Using the MODIS BRDF data, we achieved an estimate of NDVIu close to the in situ measured value (0.61 vs. 0.66 for estimate and measurement, respectively and reasonable seasonal patterns of NDVIu in 2010 to 2013. The results imply a potential application of the retrieved NDVIu to improve the estimation of overstory LAI for sparse boreal forests and ultimately to benefit studies on carbon cycle modeling over high-latitude areas.

Spatial Heterogeneity of the Forest Canopy Scales with the Heterogeneity of an Understory Shrub Based on Fractal Analysis

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Catherine K. Denny

2017-04-01

Full Text Available Spatial heterogeneity of vegetation is an important landscape characteristic, but is difficult to assess due to scale-dependence. Here we examine how spatial patterns in the forest canopy affect those of understory plants, using the shrub Canada buffaloberry (Shepherdia canadensis (L. Nutt. as a focal species. Evergreen and deciduous forest canopy and buffaloberry shrub presence were measured with line-intercept sampling along ten 2-km transects in the Rocky Mountain foothills of west-central Alberta, Canada. Relationships between overstory canopy and understory buffaloberry presence were assessed for scales ranging from 2 m to 502 m. Fractal dimensions of both canopy and buffaloberry were estimated and then related using box-counting methods to evaluate spatial heterogeneity based on patch distribution and abundance. Effects of canopy presence on buffaloberry were scale-dependent, with shrub presence negatively related to evergreen canopy cover and positively related to deciduous cover. The effect of evergreen canopy was significant at a local scale between 2 m and 42 m, while that of deciduous canopy was significant at a meso-scale between 150 m and 358 m. Fractal analysis indicated that buffaloberry heterogeneity positively scaled with evergreen canopy heterogeneity, but was unrelated to that of deciduous canopy. This study demonstrates that evergreen canopy cover is a determinant of buffaloberry heterogeneity, highlighting the importance of spatial scale and canopy composition in understanding canopy-understory relationships.

Species-specific associations between overstory and understory tree species in a semideciduous tropical forest

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Flaviana Maluf Souza

2015-03-01

Full Text Available We investigated the occurrence of associations between overstory and understory tree species in a semideciduous tropical forest. We identified and measured all trees of nine canopy species with diameter at breast height ≥4.8 cm in a 10.24 ha plot and recorded all individuals beneath their canopies ("understory individuals" within the same diameter class. The total density of understory individuals did not significantly differ under different overstory species. One overstory species (Ceiba speciosa showed higher understory species richness compared with five other species. There was a strong positive association between three overstory species (Esenbeckia leiocarpa, Savia dictyocarpa, and C. speciosa and the density of seven understory species (Balfourodendron riedelianum, Chrysophyllum gonocarpum, E. leiocarpa, Holocalyx balansae, Machaerium stipitatum, Rhaminidium elaeocarpum, and S. dictyocarpa. These results probably reflect the outcome of a complex set of interactions including facilitation and competition, and further studies are necessary to better understand the magnitude and type of the effects of individual overstory species on understory species. The occurrence of species-specific associations shown here reinforces the importance of non-random processes in structuring plant communities and suggest that the influence of overstory species on understory species in high-diversity forests may be more significant than previously thought.

Dwarf Mistletoe on Red Fir . . . infection and control in understory stands

Science.gov (United States)

Robert F. Scharpf

1969-01-01

Height and age of understory red fir (Abies magnifica A. Murr.) were related to dwarf mistletoe (Arceuthobiilm campylopodum f. abietinum) infection from the surrounding overstory red fir on four National Forests in California. Percentage of trees infected and intensity of infection increased significantly as height of understory...

Static terrestrial laser scanning of juvenile understory trees for field phenotyping

Science.gov (United States)

Wang, Huanhuan; Lin, Yi

2014-11-01

This study was to attempt the cutting-edge 3D remote sensing technique of static terrestrial laser scanning (TLS) for parametric 3D reconstruction of juvenile understory trees. The data for test was collected with a Leica HDS6100 TLS system in a single-scan way. The geometrical structures of juvenile understory trees are extracted by model fitting. Cones are used to model trunks and branches. Principal component analysis (PCA) is adopted to calculate their major axes. Coordinate transformation and orthogonal projection are used to estimate the parameters of the cones. Then, AutoCAD is utilized to simulate the morphological characteristics of the understory trees, and to add secondary branches and leaves in a random way. Comparison of the reference values and the estimated values gives the regression equation and shows that the proposed algorithm of extracting parameters is credible. The results have basically verified the applicability of TLS for field phenotyping of juvenile understory trees.

Intraspecific variability and reaction norms of forest understory plant species traits

Science.gov (United States)

Burton, Julia I.; Perakis, Steven; McKenzie, Sean C.; Lawrence, Caitlin E.; Puettmann, Klaus J.

2017-01-01

Trait-based models of ecological communities typically assume intraspecific variation in functional traits is not important, though such variation can change species trait rankings along gradients in resources and environmental conditions, and thus influence community structure and function.We examined the degree of intraspecific relative to interspecific variation, and reaction norms of 11 functional traits for 57 forest understory plant species, including: intrinsic water-use efficiency (iWUE), Δ15N, 5 leaf traits, 2 stem traits and 2 root traits along gradients in light, nitrogen, moisture and understory cover.Our results indicate that interspecific trait variation exceeded intraspecific variation by at least 50% for most, but not all traits. Intraspecific variation in Δ15N, iWUE, leaf nitrogen content and root traits was high (47-70%) compared with most leaf traits and stem traits (13-38%).Δ15N varied primarily along gradients in abiotic conditions, while light and understory cover were relatively less important. iWUE was related primarily to light transmission, reflecting increases in photosynthesis relative to stomatal conductance. Leaf traits varied mainly as a function of light availability, with some reaction norms depending on understory cover. Plant height increased with understory cover, while stem specific density was related primarily to light. Resources, environmental conditions and understory cover did not contribute strongly to the observed variation in root traits.Gradients in resources, environmental conditions and competition all appear to control intraspecific variability in most traits to some extent. However, our results suggest that species cross-over (i.e., trait rank reversals) along the gradients measured here are generally not a concern.Intraspecific variability in understory plant species traits can be considerable. However, trait data collected under a narrow range of environmental conditions appears sufficient to establish species

Temperature and substrate controls on intra-annual variation in ecosystem respiration in two subarctic vegetation types

DEFF Research Database (Denmark)

Grogan, Paul; Jonasson, Sven Evert

2005-01-01

significantly to ecosystem respiration during most phases of winter and summer in the two vegetation types. Ecosystem respiration rates through the year did not differ significantly between vegetation types despite substantial differences in biomass pools, soil depth and temperature regime. Most (76...... contributions of bulk soil organic matter and plant-associated carbon pools to ecosystem respiration is critical to predicting the response of arctic ecosystem net carbon balance to climate change. In this study, we determined the variation in ecosystem respiration rates from birch forest understory and heath......-92%) of the intra-annual variation in ecosystem respiration rates from these two common mesic subarctic ecosystems was explained using a first-order exponential equation relating respiration to substrate chemical quality and soil temperature. Removal of plants and their current year's litter significantly reduced...

Enhancement of understory productivity by asynchronous phenology with overstory competitors in a temperate deciduous forest.

Science.gov (United States)

Jolly, William M; Nemani, Ramakrishna; Running, Steven W

2004-09-01

Some saplings and shrubs growing in the understory of temperate deciduous forests extend their periods of leaf display beyond that of the overstory, resulting in periods when understory radiation, and hence productivity, are not limited by the overstory canopy. To assess the importance of the duration of leaf display on the productivity of understory and overstory trees of deciduous forests in the north eastern United States, we applied the simulation model, BIOME-BGC with climate data for Hubbard Brook Experimental Forest, New Hampshire, USA and mean ecophysiological data for species of deciduous, temperate forests. Extension of the overstory leaf display period increased overstory leaf area index (LAI) by only 3 to 4% and productivity by only 2 to 4%. In contrast, extending the growing season of the understory relative to the overstory by one week in both spring and fall, increased understory LAI by 35% and productivity by 32%. A 2-week extension of the growing period in both spring and fall increased understory LAI by 53% and productivity by 55%.

Diversity patterns of ground beetles and understory vegetation in mature, secondary, and plantation forest regions of temperate northern China.

Science.gov (United States)

Zou, Yi; Sang, Weiguo; Wang, Shunzhong; Warren-Thomas, Eleanor; Liu, Yunhui; Yu, Zhenrong; Wang, Changliu; Axmacher, Jan Christoph

2015-02-01

Plantation and secondary forests form increasingly important components of the global forest cover, but our current knowledge about their potential contribution to biodiversity conservation is limited. We surveyed understory plant and carabid species assemblages at three distinct regions in temperate northeastern China, dominated by mature forest (Changbaishan Nature Reserve, sampled in 2011 and 2012), secondary forest (Dongling Mountain, sampled in 2011 and 2012), and forest plantation habitats (Bashang Plateau, sampled in 2006 and 2007), respectively. The α-diversity of both taxonomic groups was highest in plantation forests of the Bashang Plateau. Beetle α-diversity was lowest, but plant and beetle species turnover peaked in the secondary forests of Dongling Mountain, while habitats in the Changbaishan Nature Reserve showed the lowest turnover rates for both taxa. Changbaishan Nature Reserve harbored the highest proportion of forest specialists. Our results suggest that in temperate regions of northern China, the protected larch plantation forest established over extensive areas might play a considerable role in maintaining a high biodiversity in relation to understory herbaceous plant species and carabid assemblages, which can be seen as indicators of forest disturbance. The high proportion of phytophagous carabids and the rarity of forest specialists reflect the relatively homogenous, immature status of the forest ecosystems on the Bashang Plateau. China's last remaining large old-growth forests like the ones on Changbaishan represent stable, mature ecosystems which require particular conservation attention.

Prescribed burning for understory restoration

Science.gov (United States)

Kenneth W. Outcalt

2006-01-01

Because the longleaf ecosystem evolved with and is adapted to frequent fire, every 2 to 8 years, prescribed burning is often useful for restoring understory communities to a diverse ground layer of grasses, herbs, and small shrubs. This restoration provides habitat for a number of plant and animal species that are restricted to or found mostly in longleaf pine...

Laboratory measurements of nitric oxide release from forest soil with a thick organic layer under different understory types

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A. Bargsten

2010-05-01

Full Text Available Nitric oxide (NO plays an important role in the photochemistry of the troposphere. NO from soil contributes up to 40% to the global budget of atmospheric NO. Soil NO emissions are primarily caused by biological activity (nitrification and denitrification, that occurs in the uppermost centimeter of the soil, a soil region often characterized by high contents of organic material. Most studies of NO emission potentials to date have investigated mineral soil layers. In our study we sampled soil organic matter under different understories (moss, grass, spruce and blueberries in a humid mountainous Norway spruce forest plantation in the Fichtelgebirge (Germany. We performed laboratory incubation and flushing experiments using a customized chamber technique to determine the response of net potential NO flux to physical and chemical soil conditions (water content and temperature, bulk density, particle density, pH, C/N ratio, organic C, soil ammonium, soil nitrate. Net potential NO fluxes (in terms of mass of N from soil samples taken under different understories ranged from 1.7–9.8 ng m⁻² s⁻¹ (soil sampled under grass and moss cover, 55.4–59.3 ng m⁻² s⁻¹ (soil sampled under spruce cover, and 43.7–114.6 ng m⁻² s⁻¹ (soil sampled under blueberry cover at optimum water content and a soil temperature of 10 °C. The water content for optimum net potential NO flux ranged between 0.76 and 0.8 gravimetric soil moisture for moss covered soils, between 1.0 and 1.1 for grass covered soils, 1.1 and 1.2 for spruce covered soils, and 1.3 and 1.9 for blueberry covered soils. Effects of soil physical and chemical characteristics on net potential NO flux were statistically significant (0.01 probability level only for NH₄⁺. Therefore, as an alternative explanation for the differences in soil biogenic NO emission we consider more biological factors like understory

Vegetation survey of PEN Branch wetlands

Energy Technology Data Exchange (ETDEWEB)

1991-01-01

A survey was conducted of vegetation along Pen Branch Creek at Savannah River Site (SRS) in support of K-Reactor restart. Plants were identified to species by overstory, understory, shrub, and groundcover strata. Abundance was also characterized and richness and diversity calculated. Based on woody species basal area, the Pen Branch delta was the most impacted, followed by the sections between the reactor and the delta. Species richness for shrub and groundcover strata were also lowest in the delta. No endangered plant species were found. Three upland pine areas were also sampled. In support of K Reactor restart, this report summarizes a study of the wetland vegetation along Pen Branch. Reactor effluent enters Indian Grove Branch and then flows into Pen Branch and the Pen Branch Delta.

Presence of understory shrubs constrains carbon gain in sunflecks by advance-regeneration seedlings: evidence from Quercus Rubra seedling grouwing in understory forest patches with or without evergreen shrubs present

Science.gov (United States)

E.T. Nilsen; T.T. Lei; S.W. Semones

2009-01-01

We investigated whether dynamic photosynthesis of understory Quercus rubra L. (Fagaceae) seedlings can acclimate to the altered pattern of sunflecks in forest patches with Rhododendron maximum L. (Ericaceae), an understory evergreen shrub. Maximum photosynthesis (A) and total CO2 accumulated during lightflecks was greatest for 400-s lightflecks, intermediate for 150-s...

Vegetation Dynamics and Community Assembly in Post-Agricultural Heathland

DEFF Research Database (Denmark)

Kepfer Rojas, Sebastian

that land-use legacies are still present in the soil and were important determinants of vegetation dynamics and community assembly. However, the effects of land-use legacies were mostly mediated by the understory vegetation and differed according to the functional groups. The distance to the edge, a proxy...... for the proximity to external seed sources, was an important factor affecting different components of the structure of the vegetation, demonstrating the importance of dispersal in the development of the community. My results indicate that the effect of the biotic interactions varies along abiotic gradients (e......Summary This PhD study aims at understanding how biotic, abiotic and stochastic factors interact to structure a heathland vegetation community managed under different traditional land-use practices for centuries prior to abandonment ca. 120 years ago. This study is part of one of the longest...

The environment, not space, dominantly structures the landscape patterns of the richness and composition of the tropical understory vegetation.

Directory of Open Access Journals (Sweden)

Yue-Hua Hu

Full Text Available The mechanisms driving the spatial patterns of species richness and composition are essential to the understanding of biodiversity. Numerous studies separately identify the contributions of the environment (niche process and space (neutral process to the species richness or composition at different scales, but few studies have investigated the contributions of both types of processes in the two types of data at the landscape scale. In this study, we partitioned the spatial variations in all, exotic and native understory plant species richness and composition constrained by environmental variables and space in 134 plots that were spread across 10 counties in Hainan Island in southern China. The 134 plots included 70 rubber (Hevea brasiliensis plantation plots, 50 eucalyptus (Eucalyptus urophylla plantation plots, and 14 secondary forest plots. RDA based variation partitioning was run to assess the contribution of environment and space to species richness and composition. The results showed that the environmental variables alone explained a large proportion of the variations in both the species richness and composition of all, native, and exotic species. The RDA results indicated that overstory composition (forest type here plays a leading role in determining species richness and composition patterns. The alpha and beta diversities of the secondary forest plots were markedly higher than that of the two plantations. In conclusion, niche differentiation processes are the principal mechanisms that shape the alpha and beta diversities of understory plant species in Hainan Island.

Measuring Tree Seedlings and Associated Understory Vegetation in Pennsylvania's Forests

Science.gov (United States)

William H. McWilliams; Todd W. Bowersox; Patrick H. Brose; Daniel A. Devlin; James C. Finley; Kurt W. Gottschalk; Steve Horsley; Susan L. King; Brian M. LaPoint; Tonya W. Lister; Larry H. McCormick; Gary W. Miller; Charles T. Scott; Harry Steele; Kim C. Steiner; Susan L. Stout; James A. Westfall; Robert L. White

2005-01-01

The Northeastern Research Station's Forest Inventory and Analysis (NE-FIA) unit is conducting the Pennsylvania Regeneration Study (PRS) to evaluate composition and abundance of tree seedlings and associated vegetation. Sampling methods for the PRS were tested and developed in a pilot study to determine the appropriate number of 2-m microplots needed to capture...

Influence of microtopography on soil chemistry and understory riparian vegetation

Science.gov (United States)

Irene M. Unger; Rose-Marie Muzika

2008-01-01

The success of riparian forest restoration efforts depends in part on an understanding of the relationship between soil characteristics and vegetation patterns and how these change with site conditions. To examine these relationships for floodplains in northern Missouri, we chose three unchannelized streams as study areas. A sampling grid was established at two plots...

Influence of light and soil moisture on Sierran mixed-conifer understory communities.

Science.gov (United States)

Malcolm North; Brian Oakley; Rob Fiegener; Andrew Gray; Michael. Barbour

2005-01-01

Sierra Nevada forests have high understory species richness yet we do not know which site factors influence herb and shrub distribution or abundance. We examined the understory of an old-growth mixed-conifer Sierran forest and its distribution in relation to microsite conditions. The forest has high species richness (98 species sampled), most of which are herbs with...

Vegetation index anomaly response to varying lengths of drought across vegetation and climatic gradients in Hawaii

Science.gov (United States)

Lucas, M.; Miura, T.; Trauernicht, C.; Frazier, A. G.

2017-12-01

A drought which results in prolonged and extended deficit in naturally available water supply and creates multiple stresses across ecosystems is classified as an ecological drought. Detecting and understanding the dynamics and response of such droughts in tropical systems, specifically across various vegetation and climatic gradients is fairly undetermined, yet increasingly important for better understandings of the ecological effects of drought. To understanding the link between what lengths and intensities of known meteorological drought triggers detectable ecological vegetation responses, a landscape scale regression analysis evaluating the response (slope) and relationship strength (R-squared) of several cumulative SPI (standard precipitation index) lengths(1, 3, 6, 12, 18, 24, 36, 48, and 60 month), to various satellite derived monthly vegetation indices anomalies (NDVI, EVI, EVI2, and LSWI) was performed across a matrix of dominant vegetation covers (grassland, shrubland, and forest) and climatic moisture zones (arid, dry, mesic, and wet). The nine different SPI lags across these climactic and vegetation gradients was suggest that stronger relationships and steeper slopes were found in dryer climates (across all vegetation covers) and finer vegetation types (across all moisture zones). Overall NDVI, EVI and EVI2 showed the best utility in these dryer climatic zones across all vegetation types. Within arid and dry areas "best" fits showed increasing lengths of cumulative SPI were with increasing vegetation coarseness respectively. Overall these findings suggest that rainfall driven drought may have a stronger impact on the ecological condition of vegetation in water limited systems with finer vegetation types ecologically responding more rapidly to meteorological drought events than coarser woody vegetation systems. These results suggest that previously and newly documented trends of decreasing rainfall and increasing drought in Hawaiian drylands may have

Theory, methods and tools for determining environmental flows for riparian vegetation: Riparian vegetation-flow response guilds

Science.gov (United States)

Merritt, D.M.; Scott, M.L.; Leroy, Poff N.; Auble, G.T.; Lytle, D.A.

2010-01-01

Riparian vegetation composition, structure and abundance are governed to a large degree by river flow regime and flow-mediated fluvial processes. Streamflow regime exerts selective pressures on riparian vegetation, resulting in adaptations (trait syndromes) to specific flow attributes. Widespread modification of flow regimes by humans has resulted in extensive alteration of riparian vegetation communities. Some of the negative effects of altered flow regimes on vegetation may be reversed by restoring components of the natural flow regime. 2. Models have been developed that quantitatively relate components of the flow regime to attributes of riparian vegetation at the individual, population and community levels. Predictive models range from simple statistical relationships, to more complex stochastic matrix population models and dynamic simulation models. Of the dozens of predictive models reviewed here, most treat one or a few species, have many simplifying assumptions such as stable channel form, and do not specify the time-scale of response. In many cases, these models are very effective in developing alternative streamflow management plans for specific river reaches or segments but are not directly transferable to other rivers or other regions. 3. A primary goal in riparian ecology is to develop general frameworks for prediction of vegetation response to changing environmental conditions. The development of riparian vegetation-flow response guilds offers a framework for transferring information from rivers where flow standards have been developed to maintain desirable vegetation attributes, to rivers with little or no existing information. 4. We propose to organise riparian plants into non-phylogenetic groupings of species with shared traits that are related to components of hydrologic regime: life history, reproductive strategy, morphology, adaptations to fluvial disturbance and adaptations to water availability. Plants from any river or region may be grouped

Maintenance of a living understory enhances soil carbon sequestration in subtropical orchards.

Science.gov (United States)

Liu, Zhanfeng; Lin, Yongbiao; Lu, Hongfang; Ding, Mingmao; Tan, Yaowen; Xu, Shejin; Fu, Shenglei

2013-01-01

Orchard understory represents an important component of the orchards, performing numerous functions related to soil quality, water relations and microclimate, but little attention has been paid on its effect on soil C sequestration. In the face of global climate change, fruit producers also require techniques that increase carbon (C) sequestration in a cost-effective manner. Here we present a case study to compare the effects of understory management (sod culture vs. clean tillage) on soil C sequestration in four subtropical orchards. The results of a 10-year study indicated that the maintenance of sod significantly enhanced the soil C stock in the top 1 m of orchard soils. Relative to clean tillage, sod culture increased annual soil C sequestration by 2.85 t C ha(-1), suggesting that understory management based on sod culture offers promising potential for soil carbon sequestration. Considering that China has the largest area of orchards in the world and that few of these orchards currently have sod understories, the establishment and maintenance of sod in orchards can help China increase C sequestration and greatly contribute to achieving CO2 reduction targets at a regional scale and potentially at a national scale.

Effects of the interception of litterfall by the understory on carbon cycling in eucalyptus plantations of South China.

Science.gov (United States)

Yang, Long; Wang, Jun; Huang, Yuhui; Hui, Dafeng; Wen, Meili

2014-01-01

For the purposes of forest restoration, carbon (C) fixation, and economic improvement, eucalyptus (Eucalyptus urophylla) has been widely planted in South China. The understory of eucalyptus plantations is often occupied by a dense community of the fern Dicranopteris dichotoma, which intercepts tree canopy leaf litter before it reaches the ground. To understand the effects of this interception of litterfall on C cycling in eucalyptus plantations, we quantified the mass of intercepted litter and the influences of litterfall interception on litter decomposition and soil respiration. The total mass of E. urophylla litterfall collected on the understory was similar to that collected by the traditional litter trap method. All of the eucalyptus litterfall is intercepted by the D. dichotoma canopy. Of the litterfall that was intercepted by D. dichotoma, 20-40% and 60-80% was intercepted by the top (50-100 cm) and bottom (0-50 cm) of the understory canopy, respectively. Intercepted litterfall decomposed faster at the bottom of understory canopy (at the base of the plants) than at the top, and decomposition was slower on the soil surface in the absence of understory than on any location in the understory canopy. Soil respiration was highest when both the understory and litter were present and was lowest when both the understory and litter were absent. These results indicate that litterfall interception changed carbon flow between aboveground and belowground through litter decomposition and soil respiration, which changed carbon cycling in eucalyptus plantations. The effects of the understory on litter decomposition and soil respiration should be considered in ecosystem carbon models.

Effects of the interception of litterfall by the understory on carbon cycling in eucalyptus plantations of South China.

Directory of Open Access Journals (Sweden)

Long Yang

Full Text Available For the purposes of forest restoration, carbon (C fixation, and economic improvement, eucalyptus (Eucalyptus urophylla has been widely planted in South China. The understory of eucalyptus plantations is often occupied by a dense community of the fern Dicranopteris dichotoma, which intercepts tree canopy leaf litter before it reaches the ground. To understand the effects of this interception of litterfall on C cycling in eucalyptus plantations, we quantified the mass of intercepted litter and the influences of litterfall interception on litter decomposition and soil respiration. The total mass of E. urophylla litterfall collected on the understory was similar to that collected by the traditional litter trap method. All of the eucalyptus litterfall is intercepted by the D. dichotoma canopy. Of the litterfall that was intercepted by D. dichotoma, 20-40% and 60-80% was intercepted by the top (50-100 cm and bottom (0-50 cm of the understory canopy, respectively. Intercepted litterfall decomposed faster at the bottom of understory canopy (at the base of the plants than at the top, and decomposition was slower on the soil surface in the absence of understory than on any location in the understory canopy. Soil respiration was highest when both the understory and litter were present and was lowest when both the understory and litter were absent. These results indicate that litterfall interception changed carbon flow between aboveground and belowground through litter decomposition and soil respiration, which changed carbon cycling in eucalyptus plantations. The effects of the understory on litter decomposition and soil respiration should be considered in ecosystem carbon models.

Thermogravimetric analysis of forest understory grasses

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Thomas Elder; John S. Kush; Sharon M. Hermann

2011-01-01

Forest understory grasses are of significance in the initiation, establishment and maintenance of fire, whether used as a management tool or when occurring as wildfire. The fundamental thermal properties of such grasses are critical to their behavior in fire situations and have been investigated in the current work by the application of thermogravimetric analysis (TGA...

Understory Density Characteristics in Several Midlatitude Temperature Forests

National Research Council Canada - National Science Library

Krause, Paul

2003-01-01

Understory density can have impacts on such military activities as cross-country mobility, bivouac, cover and concealment, and line of sight Airborne sensors provide a fairly good mechanism for measuring the overstory...

Floristic conservation value, nested understory floras, and the development of second-growth forest.

Science.gov (United States)

Spyreas, Greg; Matthews, Jeffrey W

2006-08-01

Nestedness analysis can reveal patterns of plant composition and diversity among forest patches. For nested floral assemblages, the plants occupying any one patch are a nested subset of the plants present in successively more speciose patches. Elimination of sensitive understory plants with human disturbance is one of several mechanisms hypothesized to generate nonrandom, nested floral distributions. Hypotheses explaining distributions of understory plants remain unsubstantiated across broad landscapes of varying forest types and disturbance histories. We sampled the vegetation of 51 floodplain and 55 upland forests across Illinois (USA) to examine how the diversity, composition, and nestedness of understory floras related to their overstory growth and structure (basal area), and their overall floristic conservation value (mean C). We found that plant assemblages were nested with respect to site species richness, such that rare plants indicated diverse forests. Floras were also nested with respect to site mean C and basal area (BA). However, in an opposite pattern from what we had expected, floras of high-BA stands were nested subsets of those of low-BA stands. A set of early-successional plants restricted to low-BA stands, and more importantly, the absence of a set of true forest plants in high-BA stands, accounted for this pattern. Additionally, we observed a decrease in species richness with increasing BA. These results are consistent with the hypothesis that recovery of true forest plants does not occur concurrently with overstory regeneration following massive anthropogenic disturbance. Nestedness by site mean C indicates that high conservation value (conservative) plants co-occur in highly diverse stands; these forests are assumed to be less disturbed historically. Because site mean C was uncorrelated with BA, BA-neutral disturbances such as livestock usage are suggested as accounting for between-site differences in mean C. When considered individually

Long-term deer exclusion has complex effects on a suburban forest understory

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Faison, Edward K.; Foster, David R.; DeStefano, Stephen

2016-01-01

Herbivory by deer is one of the leading biotic disturbances on forest understories (i.e., herbs, small shrubs, and small tree seedlings). A large body of research has reported declines in height, abundance, and reproductive capacity of forbs and woody plants coupled with increases in abundance of graminoids, ferns, and exotic species due to deer herbivory. Less clear is the extent to which (and the direction in which) deer alter herbaceous layer diversity, where much of the plant diversity in a forest occurs. We examined the effect of 15 y of deer exclusion on the understory of a suburban hardwood forest in Connecticut exposed to decades of intensive herbivory by white-tailed deer (Odocoileus virginianus). We compared species richness (at subplot and plot scale), individual species and life form group abundance (% cover), and community composition between grazed and exclosure plots, as well as between mesic and wet soil blocks. Forb cover was more than twice as abundant in exclosure as in grazed plots, whereas sedge (Carex spp.) cover was 28 times more abundant, and exotic species cover generally higher in grazed than in exclosure plots. Native and exotic species richness were both higher in grazed than exclosure plots at the subplot scale, and native herbaceous richness was higher in grazed plots at both spatial scales. In contrast, native shrub richness increased with deer exclusion at the plot scale. Our results suggest that deer exclusion had contrasting effects on species richness, depending on plant life form, but that overall richness of both exotic and native plants declined with deer exclusion. In addition, site heterogeneity remained an important driver of vegetation dynamics even in the midst of high deer densities.

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

Surface fluxes and water balance of spatially varying vegetation within a small mountainous headwater catchment

Directory of Open Access Journals (Sweden)

G. N. Flerchinger

2010-06-01

Full Text Available Precipitation variability and complex topography often create a mosaic of vegetation communities in mountainous headwater catchments, creating a challenge for measuring and interpreting energy and mass fluxes. Understanding the role of these communities in modulating energy, water and carbon fluxes is critical to quantifying the variability in energy, carbon, and water balances across landscapes. The focus of this paper was: (1 to demonstrate the utility of eddy covariance (EC systems in estimating the evapotranspiration component of the water balance of complex headwater mountain catchments; and (2 to compare and contrast the seasonal surface energy and carbon fluxes across a headwater catchment characterized by large variability in precipitation and vegetation cover. Eddy covariance systems were used to measure surface fluxes over sagebrush (Artemesia arbuscula and Artemesia tridentada vaseyana, aspen (Populus tremuloides and the understory of grasses and forbs beneath the aspen canopy. Peak leaf area index of the sagebrush, aspen, and aspen understory was 0.77, 1.35, and 1.20, respectively. The sagebrush and aspen canopies were subject to similar meteorological forces, while the understory of the aspen was sheltered from the wind. Missing periods of measured data were common and made it necessary to extrapolate measured fluxes to the missing periods using a combination of measured and simulated data. Estimated cumulative evapotranspiratation from the sagebrush, aspen trees, and aspen understory were 384 mm, 314 mm and 185 mm. A water balance of the catchment indicated that of the 699 mm of areal average precipitation, 421 mm was lost to evapotranspiration, and 254 mm of streamflow was measured from the catchment; water balance closure for the catchment was within 22 mm. Fluxes of latent heat and carbon for all sites were minimal through the winter. Growing season fluxes of latent heat and carbon were consistently higher

Monitoring of vegetation dynamics and assessing vegetation response to drought in the Iberian Peninsula

Energy Technology Data Exchange (ETDEWEB)

Garcia-Haro, F. J.; Moreno, A.; Perez-Hoyos, A.; Gilabert, M. A.; Melia, J.; Belda, F.; Poquet, D.; Martinez, B.; Verger, A.

2009-07-01

Monitoring the vegetation activity over long time-scales is necessary to discern ecosystem response to climate variability. Spatial and temporally consistent estimates of the biophysical variables such as fractional vegetation cover (FVC) and leaf area index (LAI) have been obtained in the context of DULCINEA Project. We used long-term monthly climate statistics to build simple climatic indices (SPI, moisture index) at different time scales. From these indices, we estimated that the climatic disturbances affected both the growing season and the total amount of vegetation. This implies that the anomaly of vegetation cover is a good indicator of moisture condition and can be an important data source when used for detecting an monitoring drought in the Iberian Peninsula. The impact of climate variability on the vegetation dynamics has shown not to be the same for every region. We concluded that the relationships between vegetation anomaly and moisture availability are significant for the arid and semiarid areas. (Author) 6 refs.

Monitoring of vegetation dynamics and assessing vegetation response to drought in the Iberian Peninsula

International Nuclear Information System (INIS)

Garcia-Haro, F. J.; Moreno, A.; Perez-Hoyos, A.; Gilabert, M. A.; Melia, J.; Belda, F.; Poquet, D.; Martinez, B.; Verger, A.

2009-01-01

Monitoring the vegetation activity over long time-scales is necessary to discern ecosystem response to climate variability. Spatial and temporally consistent estimates of the biophysical variables such as fractional vegetation cover (FVC) and leaf area index (LAI) have been obtained in the context of DULCINEA Project. We used long-term monthly climate statistics to build simple climatic indices (SPI, moisture index) at different time scales. From these indices, we estimated that the climatic disturbances affected both the growing season and the total amount of vegetation. This implies that the anomaly of vegetation cover is a good indicator of moisture condition and can be an important data source when used for detecting an monitoring drought in the Iberian Peninsula. The impact of climate variability on the vegetation dynamics has shown not to be the same for every region. We concluded that the relationships between vegetation anomaly and moisture availability are significant for the arid and semiarid areas. (Author) 6 refs.

Radionuclide concentrations in soils and vegetation at Low-Level Radioactive Waste Disposal Area G during the 1998 growing season (with a cumulative summary of 3H and 239Pu over time)

International Nuclear Information System (INIS)

Fresquez, P.R.; Ebinger, M.H.; Wechsler, R.J.; Naranjo, L. Jr.

1999-01-01

Soils and unwashed overstory and understory vegetation were collected at eight locations within and around Area G, a disposal facility for low-level, radioactive solid waste at Los Alamos National Laboratory. The samples were analyzed for 3 H, 238 Pu, 239 Pu, 90 Sr, 241 Am, 137 Cs, tot U. Most of the radionuclide concentrations in soils and vegetation were within the upper 95% level of background concentrations except for 3 H and 239 Pu. Tritium concentrations in vegetation from most sites were greater than background concentrations of about 2 pCi mL -1 . The concentrations of 239 Pu in soils and understory vegetation were largest in samples collected several meters north of the transuranic waste pad area and were consistent with previous results. Based on 3 H and 239 Pu data through 1998, it was shown that concentrations were (1) significantly greater than background concentrations (p < 0.05) in soils and vegetation collected from most locations at Area G, and (2) there was no systematic increase or decrease in concentrations with time apparent in the data

Mapping snags and understory shrubs for LiDAR based assessment of wildlife habitat suitability

Science.gov (United States)

Sebastian Martinuzzi; Lee A. Vierling; William A. Gould; Michael J. Falkowski; Jeffrey S. Evans; Andrew T. Hudak; Kerri T. Vierling

2009-01-01

The lack of maps depicting forest three-dimensional structure, particularly as pertaining to snags and understory shrub species distribution, is a major limitation for managing wildlife habitat in forests. Developing new techniques to remotely map snags and understory shrubs is therefore an important need. To address this, we first evaluated the use of LiDAR data for...

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.

Lianas, tree ferns and understory species: indicators of conservation status in the Brazilian Atlantic Rainforest remnants, southeastern Brazil.

Science.gov (United States)

Castello, A C D; Coelho, S; Cardoso-Leite, E

2017-01-01

Indicators are applied faster and at lower costs than conventional surveys, providing quick and efficient responses that can facilitate protected areas management. Our aim was to select indicators from vegetation to monitor protected areas. For this purpose, we analyzed understory and quantified lianas and tree ferns in protected and non-protected areas, in order to find indicator species. Our study areas are located in Vale do Ribeira, southeastern São Paulo state, Brazil. One of the areas is under two protection categories (IUCN's categories II and V), and the other is a privately owned farm. Lianas with large diameters (> 13 cm) and tree ferns with great heights (> 19 m) were considered indicators of undisturbed areas (protected areas) because their growth is directly related to forest successional stage. Indicator species within the protected area were shade tolerant species, such as Bathysa australis (A.St.-Hil.) K.Schum., whereas outside the protected area were pioneer species, such as Pera glabrata (Schott) Poepp. ex Baill. e Nectandra oppositifolia Ness. All of the suggested indicators can be used in management actions, especially in protected areas, to guarantee forest maintenance and ensure fulfillment of the conservation objectives of these areas.

Lianas, tree ferns and understory species: indicators of conservation status in the Brazilian Atlantic Rainforest remnants, southeastern Brazil

Directory of Open Access Journals (Sweden)

A. C. D. Castello

Full Text Available Abstract Indicators are applied faster and at lower costs than conventional surveys, providing quick and efficient responses that can facilitate protected areas management. Our aim was to select indicators from vegetation to monitor protected areas. For this purpose, we analyzed understory and quantified lianas and tree ferns in protected and non-protected areas, in order to find indicator species. Our study areas are located in Vale do Ribeira, southeastern São Paulo state, Brazil. One of the areas is under two protection categories (IUCN's categories II and V, and the other is a privately owned farm. Lianas with large diameters (> 13 cm and tree ferns with great heights (> 19 m were considered indicators of undisturbed areas (protected areas because their growth is directly related to forest successional stage. Indicator species within the protected area were shade tolerant species, such as Bathysa australis (A.St.-Hil. K.Schum., whereas outside the protected area were pioneer species, such as Pera glabrata (Schott Poepp. ex Baill. e Nectandra oppositifolia Ness. All of the suggested indicators can be used in management actions, especially in protected areas, to guarantee forest maintenance and ensure fulfillment of the conservation objectives of these areas.

Assessing tolerance of longleaf pine understory herbaceous plants to herbicide applications in a container nursery

Science.gov (United States)

D. Paul Jackson; Scott A. Enebak; James West; Drew Hinnant

2015-01-01

Renewed efforts in longleaf pine (Pinus palustris Mill.) ecosystem restoration has increased interest in the commercial production of understory herbaceous species. Successful establishment of understory herbaceous species is enhanced when using quality nursery-grown plants that have a better chance of survival after outplanting. Nursery growing practices have not been...

Remotely Sensed Northern Vegetation Response to Changing Climate: Growing Season and Productivity Perspective

Science.gov (United States)

Ganguly, S.; Park, Taejin; Choi, Sungho; Bi, Jian; Knyazikhin, Yuri; Myneni, Ranga

2016-01-01

Vegetation growing season and maximum photosynthetic state determine spatiotemporal variability of seasonal total gross primary productivity of vegetation. Recent warming induced impacts accelerate shifts on growing season and physiological status over Northern vegetated land. Thus, understanding and quantifying these changes are very important. Here, we first investigate how vegetation growing season and maximum photosynthesis state are evolved and how such components contribute on inter-annual variation of seasonal total gross primary productivity. Furthermore, seasonally different response of northern vegetation to changing temperature and water availability is also investigated. We utilized both long-term remotely sensed data to extract larger scale growing season metrics (growing season start, end and duration) and productivity (i.e., growing season summed vegetation index, GSSVI) for answering these questions. We find that regionally diverged growing season shift and maximum photosynthetic state contribute differently characterized productivity inter-annual variability and trend. Also seasonally different response of vegetation gives different view of spatially varying interaction between vegetation and climate. These results highlight spatially and temporally varying vegetation dynamics and are reflective of biome-specific responses of northern vegetation to changing climate.

Effects of past logging and grazing on understory plant communities in a montane Colorado forest

Science.gov (United States)

Fornwalt, P.J.; Kaufmann, M.R.; Huckaby, L.S.; Stohlgren, T.J.

2009-01-01

Throughout Pinus ponderosa-Pseudotsuga menziesii forests of the southern Colorado Front Range, USA, intense logging and domestic grazing began at the time of Euro-American settlement in the late 1800s and continued until the early 1900s. We investigated the long-term impacts of these settlement-era activities on understory plant communities by comparing understory composition at a historically logged and grazed site to that of an environmentally similar site which was protected from past use. We found that species richness and cover within functional groups rarely differed between sites in either upland or riparian areas. Multivariate analyses revealed little difference in species composition between sites on uplands, though compositional differences were apparent in riparian zones. Our findings suggest that settlement-era logging and grazing have had only minor long-term impacts on understories of upland Front Range P. ponderosa-P. menziesii forests, though they have had a greater long-term influence on riparian understories, where these activities were likely the most intense. ?? 2008 Springer Science+Business Media B.V.

Influence of primitive Biłgoraj horses on the glossy buckthorn (Frangula alnus)-dominated understory in a mixed coniferous forest

Science.gov (United States)

Klich, Daniel

2018-02-01

Changes in the understory dominated by glossy buckthorn Frangula alnus via the influence of primitive horses were analyzed in a 28-year-old enclosure in the village of Szklarnia at the Biłgoraj Horse-Breeding Centre near Janów Lubelski (eastern Poland). The analysis was conducted in 20 circular plots (30 m2) defined in adjacent, similar forest stands (enclosed and control). Disturbance by the horses, mainly through trampling, caused numerous paths to form within the glossy buckthorn-dominated understory and led to a decrease in density of stems of lower height classes (30-80 and 81-130 cm, respectively). An increase in species diversity at the expense of glossy buckthorn density was also observed. The horses' trampling caused an increase in Padus avium density and the encroachment of other woody plant species that were less shade-tolerant and grew well in soils rich in nutrients. An increase in the density of woody plants over 180 cm above ground was observed within the enclosure, which was probably the result of the horses' excretion of feces. The results presented here provide new insight into the ecological role that horses play in forest-meadow landscape mosaics, which, via altering the development of vegetation, may contribute to an increase in biodiversity within forest habitats.

Effects of visitor pressure on understory vegetation in Warsaw forested parks (Poland).

Science.gov (United States)

Sikorski, Piotr; Szumacher, Iwona; Sikorska, Daria; Kozak, Marcin; Wierzba, Marek

2013-07-01

Visitor's access to understorey vegetation in park forest stands results in the impoverishment of plant species composition and a reduction in habitat quality. The phenomenon of biotic homogenisation is typical in urban landscapes, but it can proceed differently depending on the scale, a detail that has not been observed in previous studies. This research was carried out in seven Warsaw parks (both public and restricted access). Thirty-four forested areas were randomly selected, some subjected to strong visitors' pressure and some within restricted access areas, free of such impacts. The latter category included woodlands growing in old forest and secondary habitats. Public access to the study areas contributed to the disappearance of some forest species and their replacement by cosmopolitan non-forest species, leading to loss of floristic biodiversity in areas of high ecological importance at the city scale. Some human-induced factors, including soil compaction and changes in soil pH, moisture and capillary volume, were found to cause habitat changes that favoured native non-forest plants. Despite changes in species composition, the taxonomic similarity of understorey vegetation in both categories--public access and restricted access--was comparable. In a distance gradient of measurements taken around selected individual trees, there was found to be significant variation (in light, soil pH and compaction) affecting the quality and quantity of understorey vegetation (including rare species). In conclusion, the protection of rare forest species could be achieved by limiting access to forested areas, particularly in old forest fragments, and we highly recommend its consideration in the proposal of future park restoration plans.

Response of the Fine Root Production, Phenology, and Turnover Rate of Six Shrub Species from a Subtropical Forest to a Soil Moisture Gradient and Shading

Science.gov (United States)

Fu, X.; Dai, X.; Wang, H.

2015-12-01

Knowledge of the fine root dynamics of different life forms in forest ecosystems is critical to understanding how the overall belowground carbon cycling is affected by climate change. However, our current knowledge regarding how endogenous or exogenous factors regulate the root dynamics of understory vegetation is limited. We selected a suite of study sites representing different habitats with gradients of soil moisture and solar radiation (shading or no shading). We assessed the fine root production phenology, the total fine root production, and the turnover among six understory shrub species in a subtropical climate, and examined the responses of the fine root dynamics to gradients in the soil moisture and solar radiation. The shrubs included three evergreen species, Loropetalum chinense, Vaccinium bracteatum, and Adinandra millettii, and three deciduous species, Serissa serissoides, Rubus corchorifolius, and Lespedeza davidii. We observed that variations in the annual fine root production and turnover among species were significant in the deciduous group but not in the evergreen group. Notably, V. bracteatum and S. serissoides presented the greatest responses in terms of root phenology to gradients in the soil moisture and shading: high-moisture habitat led to a decrease and shade led to an increase in fine root production during spring. Species with smaller fine roots of the 1st+2nd-order diameter presented more sensitive responses in terms of fine root phenology to a soil moisture gradient. Species with a higher fine root nitrogen-to -carbon ratio exhibited more sensitive responses in terms of fine root annual production to shading. Soil moisture and shading did not change the annual fine root production as much as the turnover rate. The fine root dynamics of some understory shrubs varied significantly with soil moisture and solar radiation status and may be different from tree species. Our results emphasize the need to study the understory fine root dynamics

Terrestrial Feedbacks Incorporated in Global Vegetation Models through Observed Trait-Environment Responses

Science.gov (United States)

Bodegom, P. V.

2015-12-01

Most global vegetation models used to evaluate climate change impacts rely on plant functional types to describe vegetation responses to environmental stresses. In a traditional set-up in which vegetation characteristics are considered constant within a vegetation type, the possibility to implement and infer feedback mechanisms are limited as feedback mechanisms will likely involve a changing expression of community trait values. Based on community assembly concepts, we implemented functional trait-environment relationships into a global dynamic vegetation model to quantitatively assess this feature. For the current climate, a different global vegetation distribution was calculated with and without the inclusion of trait variation, emphasizing the importance of feedbacks -in interaction with competitive processes- for the prevailing global patterns. These trait-environmental responses do, however, not necessarily imply adaptive responses of vegetation to changing conditions and may locally lead to a faster turnover in vegetation upon climate change. Indeed, when running climate projections, simulations with trait variation did not yield a more stable or resilient vegetation than those without. Through the different feedback expressions, global and regional carbon and water fluxes were -however- strongly altered. At a global scale, model projections suggest an increased productivity and hence an increased carbon sink in the next decades to come, when including trait variation. However, by the end of the century, a reduced carbon sink is projected. This effect is due to a downregulation of photosynthesis rates, particularly in the tropical regions, even when accounting for CO2-fertilization effects. Altogether, the various global model simulations suggest the critical importance of including vegetation functional responses to changing environmental conditions to grasp terrestrial feedback mechanisms at global scales in the light of climate change.

Evergreen understory dynamics in Coweeta forest, North Carolina

Science.gov (United States)

M.M. Dobbs; Albert J. Parker

2004-01-01

A number of studies have elucidated the distributional patterns of various components of Southern Appalachian forests. The evergreen understory here is composed largely of a dominant ericaceous shrub, Rhododendron maximum L., which is believed to be expanding and inhibiting the development of other species with consequent impacts on overall forest...

Future vegetation ecosystem response to warming climate over the Tibetan Plateau

Science.gov (United States)

Bao, Y.; Gao, Y.; Wang, Y.

2017-12-01

The amplified vegetation response to climate variability has been found over the Tibetan Plateau (TP) in recent decades. In this study, the potential impacts of 21st century climate change on the vegetation ecosystem over the TP are assessed based on the dynamic vegetation outputs of models from Coupled Model Intercomparison Project Phase 5 (CMIP5), and the sensitivity of the TP vegetation in response to warming climate was investigated. Models project a continuous and accelerating greening in future, especially in the eastern TP, which closely associates with the plant type upgrade due to the pronouncing warming in growing season.Vegetation leaf area index (LAI) increase well follows the global warming, suggesting the warming climate instead of co2 fertilization controlls the future TP plant growth. The warming spring may advance the start of green-up day and extend the growing season length. More carbon accumulation in vegetation and soil will intensify the TP carbon cycle and will keep it as a carbon sink in future. Keywords: Leaf Area Index (LAI), Climate Change, Global Dynamic Vegetation Models (DGVMs), CMIP5, Tibetan Plateau (TP)

Semi-arid vegetation response to antecedent climate and water balance windows

Science.gov (United States)

Thoma, David P.; Munson, Seth M.; Irvine, Kathryn M.; Witwicki, Dana L.; Bunting, Erin

2016-01-01

Questions Can we improve understanding of vegetation response to water availability on monthly time scales in semi-arid environments using remote sensing methods? What climatic or water balance variables and antecedent windows of time associated with these variables best relate to the condition of vegetation? Can we develop credible near-term forecasts from climate data that can be used to prepare for future climate change effects on vegetation? Location Semi-arid grasslands in Capitol Reef National Park, Utah, USA. Methods We built vegetation response models by relating the normalized difference vegetation index (NDVI) from MODIS imagery in Mar–Nov 2000–2013 to antecedent climate and water balance variables preceding the monthly NDVI observations. We compared how climate and water balance variables explained vegetation greenness and then used a multi-model ensemble of climate and water balance models to forecast monthly NDVI for three holdout years. Results Water balance variables explained vegetation greenness to a greater degree than climate variables for most growing season months. Seasonally important variables included measures of antecedent water input and storage in spring, switching to indicators of drought, input or use in summer, followed by antecedent moisture availability in autumn. In spite of similar climates, there was evidence the grazed grassland showed a response to drying conditions 1 mo sooner than the ungrazed grassland. Lead times were generally short early in the growing season and antecedent window durations increased from 3 mo early in the growing season to 1 yr or more as the growing season progressed. Forecast accuracy for three holdout years using a multi-model ensemble of climate and water balance variables outperformed forecasts made with a naïve NDVI climatology. Conclusions We determined the influence of climate and water balance on vegetation at a fine temporal scale, which presents an opportunity to forecast vegetation

Wood and understory production under a range of ponderosa pine stocking levels, Black Hills, South Dakota

Science.gov (United States)

Daniel W. Uresk; Carleton B. Edminster; Kieth E. Severson

2000-01-01

Stemwood and understory production (kg ha-1) were estimated during 3 nonconsecutive years on 5 growing stock levels of ponderosa pine including clearcuts and unthinned stands. Stemwood production was consistently greater at mid- and higher pine stocking levels, and understory production was greater in stands with less pine; however, there were no...

Dense understory dwarf bamboo alters the retention of canopy tree seeds

Science.gov (United States)

Qian, Feng; Zhang, Tengda; Guo, Qinxue; Tao, Jianping

2016-05-01

Tree seed retention is thought to be an important factor in the process of forest community regeneration. Although dense understory dwarf bamboo has been considered to have serious negative effects on the regeneration of forest community species, little attention has been paid to the relationship between dwarf bamboo and seed retention. In a field experiment we manipulated the density of Fargesia decurvata, a common understory dwarf bamboo, to investigate the retention of seeds from five canopy tree species in an evergreen and deciduous broad-leaved mixed forest in Jinfoshan National Nature Reserve, SW China. We found that the median survival time and retention ratio of seeds increased with the increase in bamboo density. Fauna discriminately altered seed retention in bamboo groves of different densities. Arthropods reduced seed survival the most, and seeds removed decreased with increasing bamboo density. Birds removed or ate more seeds in groves of medium bamboo density and consumed fewer seeds in dense or sparse bamboo habitats. Rodents removed a greater number of large and highly profitable seeds in dense bamboo groves but more small and thin-husked seeds in sparse bamboo groves. Seed characteristics, including seed size, seed mass and seed profitability, were important factors affecting seed retention. The results suggested that dense understory dwarf bamboo not only increased seeds concealment and reduced the probability and speed of seed removal but also influenced the trade-off between predation and risk of animal predatory strategies, thereby impacting the quantity and composition of surviving seeds. Our results also indicated that dense understory dwarf bamboo and various seed characteristics can provide good opportunities for seed storage and seed germination and has a potential positive effect on canopy tree regeneration.

Species-specific growth responses to climate variations in understory trees of a Central African rain forest

NARCIS (Netherlands)

Couralet, C.; Sterck, F.J.; Sass-Klaassen, U.; Acker, Van J.; Beekman, H.

2010-01-01

Basic knowledge of the relationships between tree growth and environmental variables is crucial for understanding forest dynamics and predicting vegetation responses to climate variations. Trees growing in tropical areas with a clear seasonality in rainfall often form annual growth rings. In the

Radionuclide concentrations in soils and vegetation at Low-Level Radioactive Waste Disposal Area G during the 1998 growing season (with a cumulative summary of {sup 3}H and {sup 239}Pu over time)

Energy Technology Data Exchange (ETDEWEB)

P. R. Fresquez; M. H. Ebinger; R. J. Wechsler; L. Naranjo, Jr.

1999-11-01

Soils and unwashed overstory and understory vegetation were collected at eight locations within and around Area G, a disposal facility for low-level, radioactive solid waste at Los Alamos National Laboratory. The samples were analyzed for {sup 3}H, {sup 238}Pu, {sup 239}Pu, {sup 90}Sr, {sup 241}Am, {sup 137}Cs, {sup tot}U. Most of the radionuclide concentrations in soils and vegetation were within the upper 95% level of background concentrations except for {sup 3}H and {sup 239}Pu. Tritium concentrations in vegetation from most sites were greater than background concentrations of about 2 pCi mL{sup {minus}1}. The concentrations of {sup 239}Pu in soils and understory vegetation were largest in samples collected several meters north of the transuranic waste pad area and were consistent with previous results. Based on {sup 3}H and {sup 239}Pu data through 1998, it was shown that concentrations were (1) significantly greater than background concentrations (p < 0.05) in soils and vegetation collected from most locations at Area G, and (2) there was no systematic increase or decrease in concentrations with time apparent in the data.

Herbivores modify selection on plant functional traits in a temperate rainforest understory.

Science.gov (United States)

Salgado-Luarte, Cristian; Gianoli, Ernesto

2012-08-01

There is limited evidence regarding the adaptive value of plant functional traits in contrasting light environments. It has been suggested that changes in these traits in response to light availability can increase herbivore susceptibility. We tested the adaptive value of plant functional traits linked with carbon gain in contrasting light environments and also evaluated whether herbivores can modify selection on these traits in each light environment. In a temperate rainforest, we examined phenotypic selection on functional traits in seedlings of the pioneer tree Aristotelia chilensis growing in sun (canopy gap) and shade (forest understory) and subjected to either natural herbivory or herbivore exclusion. We found differential selection on functional traits depending on light environment. In sun, there was positive directional selection on photosynthetic rate and relative growth rate (RGR), indicating that selection favors competitive ability in a high-resource environment. Seedlings with high specific leaf area (SLA) and intermediate RGR were selected in shade, suggesting that light capture and conservative resource use are favored in the understory. Herbivores reduced the strength of positive directional selection acting on SLA in shade. We provide the first demonstration that natural herbivory rates can change the strength of selection on plant ecophysiological traits, that is, attributes whose main function is resource uptake. Research addressing the evolution of shade tolerance should incorporate the selective role of herbivores.

Broad-Scale Environmental Conditions Responsible for Post-Fire Vegetation Dynamics

OpenAIRE

Casady, Grant M.; Marsh, Stuart E.

2010-01-01

Ecosystem response to disturbance is influenced by environmental conditions at a number of scales. Changes in climate have altered fire regimes across the western United States, and have also likely altered spatio-temporal patterns of post-fire vegetation regeneration. Fire occurrence data and a vegetation index (NDVI) derived from the NOAA Advanced Very High Resolution Radiometer (AVHRR) were used to monitor post-fire vegetation from 1989 to 2007. We first investigated differences in post-fi...

Mechanisms for success after long-term nutrient enrichment in a boreal forest understory.

Directory of Open Access Journals (Sweden)

Tess Nahanni Grainger

Full Text Available Global levels of reactive nitrogen are predicted to rise in the coming decades as a result of increased deposition from the burning of fossil fuels and the large-scale conversion of nitrogen into a useable form for agriculture. Many plant communities respond strongly to increases in soil nitrogen, particularly in northern ecosystems where nitrogen levels are naturally very low. An experiment in northern Canada that was initiated in 1990 has been investigating the effects of long-term nutrient enrichment (fertilizer added annually on a boreal forest understory community. We used this experiment to investigate why some species increase in abundance under nutrient enrichment whereas others decline. We focused on four species that differed in their responses to fertilization: Mertensia paniculata and Epilobium angustifolium increased in abundance, Achillea millefolium remained relatively constant and Festuca altaica declined. We hypothesized that the two species that were successful in the new high-nutrient, light-limited environment would be taller, have higher specific leaf area, change phenology by growing earlier in the season and be more morphologically plastic than their less successful counterparts. We compared plant height, specific leaf area, growth spurt date and allocation to leaves in plants grown in control and fertilized plots. We demonstrated that each of the two species that came to dominate fertilized plots has a different combination of traits and responses that likely gave them a competitive advantage; M. paniculata has the highest specific leaf area of the four species whereas E. angustifolium is tallest and exhibits morphological plasticity when fertilized by increasing biomass allocation to leaves. These results indicate that rather than one strategy determining success when nutrients become available, a variety of traits and responses may contribute to a species' ability to persist in a nutrient-enriched boreal forest

Photochemical efficiency of adult and young leaves of the neotropical understory shrub Psychotria limonensis (Rubiaceaein response to changes in the light environment

Directory of Open Access Journals (Sweden)

Gerardo Avalos

2004-12-01

Full Text Available We explored the short-term adjustment in photochemical efficiency (Fv /Fm in adult and young leaves of the understory neotropical shrub Psychotria limonensis Krause (Rubiaceaein response to rapid changes in the light environment.Leaves were collected from 20 individual plants growing under sun and shade conditions on Gigante Peninsula,Barro Colorado Natural Monument (Republic of Panama,during the wet season of 1996. Leaves were distributed in four sequences of light treatments (AB leaves were expanded under sun and were transferred to shade,BA leaves experienced the opposite transfer,and the controls AA and BB leaves that were expanded and maintained under sun or shade conditions.Adult and young leaves did not differ in overall photochemical efficiency.Instead,differences were found among light environments,for which leaves transferred from shade to sun showed the lowest F v /F m ratios.There was no relationship between photochemical efficiency and leaf temperature.In P.limonensis,understory plants are susceptible of photoinhibition independently of the leaf ontogenetic stage.The approach utilized in this experiment allowed the rapid exploration of this capacity, and could be applied to poorly studied understory species. Rev.Biol.Trop.52(4:839-844.Epub 2005 Jun 24.Se exploró el ajuste a corto plazo en la eficiencia fotosintética (Fv /Fm en hojas jovenes y adultas del arbusto del sotobosque neotropical Psychotria limonensis Krause (Rubiaceaeen respuesta a cambios rápidos de luz ambiental. Las hojas fueron recolectadas de 20 plantas individuales bajo condiciones de sol y sombra en Peninsula Gigante, Monumento Natural Barro Colorado (Panamá,durante la estación lluviosa de 1996.Las hojas fueron distribuidas en una secuencia cuatro tratamientos de luz (AB las hojas fueron expandidas bajo el sol y fueron transferidas a la sombra,BA las hojas experimentaron la transferencia contraria,y las hojas controles AA y BB que fueron expandidas y mantenidas

Deforestation fires versus understory fires in the Amazon Basin: What can we learn from satellite-based CO measurements?

Science.gov (United States)

Martinez-Alonso, S.; Deeter, M. N.; Worden, H. M.; Gille, J. C.; Clerbaux, C.; George, M.

2014-12-01

Deforestation fires in the Amazon Basin abound during the dry season (July to October) and are mostly associated with "slash and burn" agricultural practices. Understory fires occur when fires escape from deforested areas into neighboring standing forests; they spread slowly below the canopy, affecting areas that may be comparable or even larger than clear-cut areas. The interannual variabilities of understory fires and deforestation rates appear to be uncorrelated. Areas burned in understory fires are particularly extensive during droughts. Because they progress below a canopy of living trees, understory fires and their effects are not as easily identifiable from space as deforestation fires. Here we analyze satellite remote sensing products for CO and fire to investigate differences between deforestation fires and understory fires in the Amazon Basin under varying climatic conditions. The MOPITT (Measurements Of Pollution In The Troposphere) instrument on board NASA's Terra satellite has been measuring tropospheric CO since 2000, providing the longest global CO record to date. IASI (the Infrared Atmospheric Sounding Interferometer) A and B are two instruments on board METOP-A and -B, respectively, measuring, among others, CO since 2006 and 2012. MODIS (the Moderate Resolution Imaging Spectroradiometer) instruments on board NASA's Terra and Aqua satellites provide, among other products, a daily record of fires and their effects since 2000 and 2002, respectively. The temporal extent of all these datasets allows for the detailed analysis of drought versus non-drought years. Initial results indicate that MOPITT CO emissions during the dry season peaked in 2005, 2007, and 2010. Those were draught years and coincide with peaks in area affected by understory fires.

The formation of dense understory layers in forests worldwide: consequences and implications for forest dynamics, biodiversity, and succession

Science.gov (United States)

Alejandro A. Royo; Walter P. Carson

2010-01-01

Alterations to natural herbivore and disturbance regimes often allow a select suite of forest understory plant species to dramatically spread and form persistent, mono-dominant thickets. Following their expansion, this newly established understory canopy can alter tree seedling recruitment rates and exert considerable control over the rate and direction of secondary...

Vegetation Response to Western Juniper Slash Treatments

Science.gov (United States)

O'Connor, Casey; Miller, Rick; Bates, Jonathan D.

2013-09-01

The expansion of piñon-juniper woodlands the past 100 years in the western United States has resulted in large scale efforts to kill trees and recover sagebrush steppe rangelands. It is important to evaluate vegetation recovery following woodland control to develop best management practices. In this study, we compared two fuel reduction treatments and a cut-and-leave (CUT) treatment used to control western juniper ( Juniperus occidentalis spp. occidentalis Hook.) of the northwestern United States. Treatments were; CUT, cut-and-broadcast burn (BURN), and cut-pile-and-burn the pile (PILE). A randomized complete block design was used with five replicates of each treatment located in a curl leaf mahogany ( Cercocarpus ledifolius Nutt. ex Torr. & A. Gray)/mountain big sagebrush ( Artemisia tridentata Nutt. spp. vaseyana (Rydb.) Beetle)/Idaho fescue ( Festuca idahoensis Elmer) association. In 2010, 4 years after tree control the cover of perennial grasses (PG) [Sandberg's bluegrass ( Poa secunda J. Pres) and large bunchgrasses] were about 4 and 5 % less, respectively, in the BURN (7.1 ± 0.6 %) than the PILE (11.4 ± 2.3 %) and CUT (12.4 ± 1.7 %) treatments ( P < 0.0015). In 2010, cover of invasive cheatgrass ( Bromus tectorum L.) was greater in the BURN (6.3 ± 1.0 %) and was 50 and 100 % greater than PILE and CUT treatments, respectively. However, the increase in perennial bunchgrass density and cover, despite cheatgrass in the BURN treatment, mean it unlikely that cheatgrass will persist as a major understory component. In the CUT treatment mahogany cover increased 12.5 % and density increased in from 172 ± 25 to 404 ± 123 trees/ha. Burning, killed most or all of the adult mahogany, and mahogany recovery consisted of 100 and 67 % seedlings in the PILE and BURN treatments, respectively. After treatment, juniper presence from untreated small trees (<1 m tall; PILE and CUT treatments) and seedling emergence (all treatments) represented 25-33 % of pre-treatment tree

Dry coniferous forest restoration and understory plant diversity: The importance of community heterogeneity and the scale of observation

Science.gov (United States)

Erich Kyle Dodson; David W. Peterson

2010-01-01

Maintaining understory plant species diversity is an important management goal as forest restoration and fuel reduction treatments are applied extensively to dry coniferous forests of western North America. However, understory diversity is a function of both local species richness (number of species in a sample unit) and community heterogeneity (beta diversity) at...

Spatial and temporal variability of canopy cover and understory light in a Cerrado of Southern Brazil

Directory of Open Access Journals (Sweden)

JP. Lemos-Filho

Full Text Available Canopy cover has significant effects on the understory environment, including upon light availability for seedling growth. The aim of the present study was to verify spatial heterogeneity and seasonal changes in the canopy cover of a dense Cerrado area, and their relationship to understory photosynthetic active radiation availability. Leaf area index (LAI values in the rainy season varied from 0.9 to 4.83, with 40% of the values ranging from 4.0 to 5.0, while in the dry season LAI varied from 0.74 to 3.3, with 53% of the values oscilating from 2.0 to 3.0. Understory light (Qi and the Lambert-Beer ratio (Qi/Qo were taken around noon on sunny days (between 11:00 AM and 1:00 PM. They were also statistically different (p < 0.01 between the dry and wet seasons, with 72% of sampled points in the rainy season presenting photosynthetic photon flux density (PPFD values lower than 250 μmol.m-2/s around noon, whereas in the dry season, most PPFD values varied from 1500 to 1817 μmol.m-2/s , thus providing high light availability for understory plants. In most of the studied sites, understory plants did not even receive enough light for 50% of their photosynthetic capacity in the wet season. In contrast during the dry season, Qi/Qo values of 0.8 to 1.0 were observed in more than 50% of the points, thereby allowing for photosynthetic light saturation. Thus, light variability around noon was higher during the dry season than in the wet season, its heterogeneity being related to spatial complexity in the canopy cover.

Examining spring phenology of forest understory using digital photography

Science.gov (United States)

Liang Liang; Mark D. Schwartz; Songlin Fei

2011-01-01

Phenology is an important indicator of forest health in relation to energy/nutrient cycles and species interactions. Accurate characterization of forest understory phenology is a crucial part of forest phenology observation. In this study, ground plots set up in a temperate mixed forest in Wisconsin were observed with a visible-light digital camera during spring 2007....

Vegetable parenting practices scale: Item response modeling analyses

Science.gov (United States)

Our objective was to evaluate the psychometric properties of a vegetable parenting practices scale using multidimensional polytomous item response modeling which enables assessing item fit to latent variables and the distributional characteristics of the items in comparison to the respondents. We al...

Variation of Vegetation Ecological Water Consumption and Its Response to Vegetation Coverage Changes in the Rocky Desertification Areas in South China.

Science.gov (United States)

Wan, Long; Tong, Jing; Zhou, Jinxing; Guo, Hongyan; Cui, Ming; Liu, Yuguo; Ning, Like; Tang, Fukai

2016-01-01

Over the past several decades, rocky desertification has led to severe ecological problems in karst areas in South China. After a rocky desertification treatment project was completed, the vegetation coverage changed greatly and, consequently, increased the ecology water consumption (approximately equal to the actual evapotranspiration) of the regional vegetation. Thus, it intensified the regional water stresses. This study explored the changes in the actual evapotranspiration (ETa) response to the vegetation coverage changes in the rocky desertification areas in South China based on the precipitation (P), potential evapotranspiration (ETp) and NDVI (the normalized difference vegetation index) datasets. The revised Bagrov model was used to simulate the actual evapotranspiration changes with the supposed increasing NDVI. The results indicated that the average NDVI value was lower when the rocky desertification was more severe. The ETa, evapotranspiration efficiency (ETa/ETp) and potential humidity (P/ETp) generally increased with the increasing NDVI. The sensitivity of the ETa response to vegetation coverage changes varied due to different precipitation conditions and different rocky desertification severities. The ETa was more sensitive under drought conditions. When a drought occurred, the ETa exhibited an average increase of 40~60 mm with the NDVI increasing of 0.1 in the rocky desertification areas. Among the 5 different severity categories of rocky desertification, the ETa values' responses to NDVI changes were less sensitive in the severe rocky desertification areas but more sensitive in the extremely and potential rocky desertification areas. For example, with the NDVI increasing of 0.025, 0.05, 0.075, and 0.1, the corresponding ETa changes increased by an average of 2.64 mm, 10.62 mm, 19.19 mm, and 27.58 mm, respectively, in severe rocky desertification areas but by 4.94 mm, 14.99 mm, 26.80, and 37.13 mm, respectively, in extremely severe rocky

Vegetation physiology controls continental water cycle responses to climate change

Science.gov (United States)

Lemordant, L. A.; Swann, A. L. S.; Cook, B.; Scheff, J.; Gentine, P.

2017-12-01

Abstract per se:Predicting how climate change will affect the hydrologic cycle is of utmost importance for ecological systems and for human life and activities. A typical perspective is that global warming will cause an intensification of the mean state, the so-called "dry gets drier, wet gets wetter" paradigm. While this result is robust over the oceans, recent works suggest it may be less appropriate for terrestrial regions. Using Earth System Models (ESMs) with decoupled surface (vegetation physiology, PHYS) and atmospheric (radiative, ATMO) CO2 responses, we show that the CO2 physiological response dominates the change in the continental hydrologic cycle compared to radiative and precipitation changes due to increased atmospheric CO2, counter to previous assumptions. Using multiple linear regression analysis, we estimate the individual contribution of each of the three main drivers, precipitation, radiation and physiological CO2 forcing (see attached figure). Our analysis reveals that physiological effects dominate changes for 3 key indicators of dryness and/or vegetation stress (namely LAI, P-ET and EF) over the largest fraction of the globe, except for soil moisture which exhibits a more complex response. This highlights the key role of vegetation in controlling future terrestrial hydrologic response.Legend of the Figure attached:Decomposition along the three main drivers of LAI (a), P-ET (b), EF (c) in the control run. Green quantifies the effect of the vegetation physiology based on the run PHYS; red and blue quantify the contribution of, respectively, net radiation and precipitation, based on multiple linear regression in ATMO. Pie charts show for each variable the fraction (labelled in %) of land under the main influence (more than 50% of the changes is attributed to this driver) of one the three main drivers (green for grid points dominated by vegetation physiology, red for grid points dominated by net radiation, and blue for grid points dominated by the

Forest soil CO2 fluxes as a function of understory removal and N-fixing species addition.

Science.gov (United States)

Li, Haifang; Fu, Shenglei; Zhao, Hongting; Xia, Hanping

2011-01-01

We report on the effects of forest management practices of understory removal and N-fixing species (Cassia alata) addition on soil CO2 fluxes in an Eucalyptus urophylla plantation (EUp), Acacia crassicarpa plantation (ACp), 10-species-mixed plantation (Tp), and 30-species-mixed plantation (THp) using the static chamber method in southern China. Four forest management treatments, including (1) understory removal (UR); (2) C. alata addition (CA); (3) understory removal and replacement with C. alata (UR+CA); and (4) control without any disturbances (CK), were applied in the above four forest plantations with three replications for each treatment. The results showed that soil CO2 fluxes rates remained at a high level during the rainy season (from April to September), followed by a rapid decrease after October reaching a minimum in February. Soil CO2 fluxes were significantly higher (P plantations under various management practices.

Broad-Scale Environmental Conditions Responsible for Post-Fire Vegetation Dynamics

Directory of Open Access Journals (Sweden)

Stuart E. Marsh

2010-11-01

Full Text Available Ecosystem response to disturbance is influenced by environmental conditions at a number of scales. Changes in climate have altered fire regimes across the western United States, and have also likely altered spatio-temporal patterns of post-fire vegetation regeneration. Fire occurrence data and a vegetation index (NDVI derived from the NOAA Advanced Very High Resolution Radiometer (AVHRR were used to monitor post-fire vegetation from 1989 to 2007. We first investigated differences in post-fire rates of vegetation regeneration between ecoregions. We then related precipitation, temperature, and elevation records at four temporal scales to rates of post-fire vegetation regeneration to ascertain the influence of climate on post-fire vegetation dynamics. We found that broad-scale climate factors are an important influence on post-fire vegetation regeneration. Most notably, higher rates of post-fire regeneration occurred with warmer minimum temperatures. Increases in precipitation also resulted in higher rates of post-fire vegetation growth. While explanatory power was slight, multiple statistical approaches provided evidence for real ecological drivers of post-fire regeneration that should be investigated further at finer scales. The sensitivity of post-disturbance vegetation dynamics to climatic drivers has important ramifications for the management of ecosystems under changing climatic conditions. Shifts in temperature and precipitation regimes are likely to result in changes in post-disturbance dynamics, which could represent important feedbacks into the global climate system.

Productivity and cost of conventional understory biomass harvesting systems

Science.gov (United States)

Douglas E. Miller; Thomas J. Straka; Bryce J. Stokes; William Watson

1987-01-01

Conventional harvesting equipment was tested for removing forest understory biomass (energywood) for use as fuel. Two types of systems were tested--a one-pass system and a two-pass system. In the one-pass system, the energywood and pulpwood were harvested simultaneously. In the two-pass system, the energywood was harvested in a first pass through the stand, and the...

Radionuclide Concentrations in soils an Vegetation at Low-Level Radioactive Waste Disposal Area G During 2004

International Nuclear Information System (INIS)

Fresquez, P.R.; Lopez, E.A.

2004-01-01

Soil samples were collected at 15 locations and unwashed overstory and understory vegetation samples were collected at nine locations within and around the perimeter of Area G, the primary disposal facility for low-level radioactive solid waste at Los Alamos National Laboratory (LANL). These samples were analyzed for 3 H, 238 Pu, 239,240 Pu, 90 Sr, 241 Am, 137 Cs, 234 U, 235 U, and 238 U. Soil samples collected at Area G contained detectable concentrations of 3H (27%), 239,240 Pu (60%), 238 Pu (40%), and 241 Am (47%) above regional statistical reference levels (RSRLs). In contrast, the levels of 137 Cs, 90 Sr, and U in all of the soil samples at Area G were either nondetectable or within RSRLs. The highest levels of 3 H in soils were detected in the southwestern portion of Area G near the 3 H shafts, whereas the highest concentrations of the Pu isotopes were detected in the northern and northeastern portions. All concentrations of 3 H and Pu in soils, however, were far below LANL screening action levels. As for vegetation, most radionuclides in/on plants were either nondetectable or within RSRLs. The exceptions were 3 H in overstory and some understory vegetation, particularly in the southwestern portion of Area G, which correlated very well with the soils data in that area. Also, there was some foliar contamination from 241 Am and Pu isotopes in/on a few plant samples--the highest concentrations occurring in the northern section of Area G

Changes in understory species occurrence of a secondary broadleaved forest after mass mortality of oak trees under deer foraging pressure

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Hiroki Itô

2016-12-01

Full Text Available The epidemic of mass mortality of oak trees by Japanese oak wilt has affected secondary deciduous broadleaved forests that have been used as coppices in Japan. The dieback of oak trees formed gaps in the crown that would be expected to enhance the regeneration of shade-intolerant pioneer species. However, foraging by sika deer Cervus nippon has also affected forest vegetation, and the compound effects of both on forest regeneration should be considered when they simultaneously occur. A field study was conducted in Kyôto City, Japan to investigate how these compound effects affected the vegetation of the understory layer of these forests. The presence/absence of seedlings and saplings was observed for 200 quadrats sized 5 m ×5 m for each species in 1992, before the mass mortality and deer encroachment, and in 2014 after these effects. A hierarchical Bayesian model was constructed to explain the occurrence, survival, and colonization of each species with their responses to the gaps that were created, expanded, or affected by the mass mortality of Quercus serrata trees. The species that occurred most frequently in 1992, Eurya japonica, Quercus glauca, and Cleyera japonica, also had the highest survival probabilities. Deer-unpalatable species such as Symplocos prunifolia and Triadica sebifera had higher colonization rates in the gaps, while the deer-palatable species Aucuba japonica had the smallest survival probability. The gaps thus promoted the colonization of deer-unpalatable plant species such as Symplocos prunifolia and Triadica sebifera. In the future, such deer-unpalatable species may dominate gaps that were created, expanded, or affected by the mass mortality of oak trees.

Opposing Responses of Bird Functional Diversity to Vegetation Structural Diversity in Wet and Dry Forest.

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Holly Sitters

Full Text Available Disturbance regimes are changing worldwide, and the consequences for ecosystem function and resilience are largely unknown. Functional diversity (FD provides a surrogate measure of ecosystem function by capturing the range, abundance and distribution of trait values in a community. Enhanced understanding of the responses of FD to measures of vegetation structure at landscape scales is needed to guide conservation management. To address this knowledge gap, we used a whole-of-landscape sampling approach to examine relationships between bird FD, vegetation diversity and time since fire. We surveyed birds and measured vegetation at 36 landscape sampling units in dry and wet forest in southeast Australia during 2010 and 2011. Four uncorrelated indices of bird FD (richness, evenness, divergence and dispersion were derived from six bird traits, and we investigated responses of these indices and species richness to both vertical and horizontal vegetation diversity using linear mixed models. We also considered the extent to which the mean and diversity of time since fire were related to vegetation diversity. Results showed opposing responses of FD to vegetation diversity in dry and wet forest. In dry forest, where fire is frequent, species richness and two FD indices (richness and dispersion were positively related to vertical vegetation diversity, consistent with theory relating to environmental variation and coexistence. However, in wet forest subject to infrequent fire, the same three response variables were negatively associated with vertical diversity. We suggest that competitive dominance by species results in lower FD as vegetation diversity increases in wet forest. The responses of functional evenness were opposite to those of species richness, functional richness and dispersion in both forest types, highlighting the value of examining multiple FD metrics at management-relevant scales. The mean and diversity of time since fire were uncorrelated

Opposing Responses of Bird Functional Diversity to Vegetation Structural Diversity in Wet and Dry Forest.

Science.gov (United States)

Sitters, Holly; York, Alan; Swan, Matthew; Christie, Fiona; Di Stefano, Julian

2016-01-01

Disturbance regimes are changing worldwide, and the consequences for ecosystem function and resilience are largely unknown. Functional diversity (FD) provides a surrogate measure of ecosystem function by capturing the range, abundance and distribution of trait values in a community. Enhanced understanding of the responses of FD to measures of vegetation structure at landscape scales is needed to guide conservation management. To address this knowledge gap, we used a whole-of-landscape sampling approach to examine relationships between bird FD, vegetation diversity and time since fire. We surveyed birds and measured vegetation at 36 landscape sampling units in dry and wet forest in southeast Australia during 2010 and 2011. Four uncorrelated indices of bird FD (richness, evenness, divergence and dispersion) were derived from six bird traits, and we investigated responses of these indices and species richness to both vertical and horizontal vegetation diversity using linear mixed models. We also considered the extent to which the mean and diversity of time since fire were related to vegetation diversity. Results showed opposing responses of FD to vegetation diversity in dry and wet forest. In dry forest, where fire is frequent, species richness and two FD indices (richness and dispersion) were positively related to vertical vegetation diversity, consistent with theory relating to environmental variation and coexistence. However, in wet forest subject to infrequent fire, the same three response variables were negatively associated with vertical diversity. We suggest that competitive dominance by species results in lower FD as vegetation diversity increases in wet forest. The responses of functional evenness were opposite to those of species richness, functional richness and dispersion in both forest types, highlighting the value of examining multiple FD metrics at management-relevant scales. The mean and diversity of time since fire were uncorrelated with vegetation

Disking and mid- and understory removal following an above-average acorn crop in three mature oak forests in southern Indiana

Science.gov (United States)

Ronald A. Rathfon; Nathanael I. Lichti; Robert K. Swihart

2008-01-01

We disked using small-scale equipment in the understory of three mature upland oak (Quercus) forests in southern Indiana immediately following acorn dispersal in an aboveaverage seed crop year as a means of improving oak seedling establishment. Three different mid- and understory removal treatments were also applied to create favorable light...

Loblolly pine seedling response to competition from exotic vs. native plants

Science.gov (United States)

Pedram Daneshgar; Shibu Jose; Craig Ramsey; Robin Collins

2006-01-01

A field study was conducted in Santa Rosa County, FL to test the hypothesis that an exotic understory would exert a higher degree of competition on tree seedling establishment and growth than native vegetation. The study site was a 60 ha cutover area infested with the invasive exotic cogongrass [Imperata cylindrica (L.) Raeusch.]. A completely...

Performance of tropical legumes grown as understory of a eucalypt plantation in a seasonally dry area of the Brazilian Cerrado

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Maria Luiza F. Nicodemo

2015-09-01

Full Text Available Nine tropical legumes were grown outside the canopy and in the understory of an 8-year-old Eucalyptus grandis stand in order to assess their seasonal production and forage quality for 4 evaluation periods. Incident photosynthetically active radiation in the understory was 18% of that outside the canopy. In the understory, production of Lablab purpureus, Centrosema schiedeanum, Clitoria ternatea, Pueraria phaseoloides, Alysicarpus vaginalis, Aeschynomene villosa, Estilosantes Campo Grande (Stylosanthes capitata + S. macrocephala, Calopogonium mucunoides and Arachis pintoi was <1 kg/ha/d for most samples. Even considering this low production, the large area available for animal production in forest plantations might justify the interest in legumes because of their high nutritive value. Lablab purpureus produced the greatest amount of dry matter in the understory in the establishment phase (12.1 kg/ha/d, but did not persist. It could be a suitable candidate for a cover legume species mixture to provide early growth. Centrosema schiedeanum developed rapidly and showed a high capacity for ground cover (>70% and persistence, and had high nitrogen concentration, thus demonstrating good potential for protecting soils and promoting nutrient cycling in forest plantations. Another species with potential is A. pintoi, which established slowly but towards the end of the experiment showed moderate to high understory ground cover.Keywords: Dry matter production, forage quality, shade, silvopastoral system.DOI: 10.17138/TGFT(3151-160

Physiological, morphological and allocational plasticity in understory deciduous trees: importance of plant size and light availability.

Science.gov (United States)

Delagrange, Sylvain; Messier, Christian; Lechowicz, Martin J; Dizengremel, Pierre

2004-07-01

In a 4-year study, we investigated changes in leaf physiology, crown morphology and whole-tree biomass allocation in seedlings and saplings of shade-tolerant sugar maple (Acer saccharum Marsh.) and intermediate shade-tolerant yellow birch (Betula alleghaniensis Britt.) growing in natural understory light (0.5 to 35% of full sunlight) or in understory light reduced by 50% with shade nets to simulate the effect of gap closure. Leaf physiological parameters were mainly influenced by the light gradient, whereas crown morphological and whole-tree allocational parameters were mainly influenced by tree size. No single physiological, morphological or allocational trait was identified that could explain the difference in shade tolerance between the species. Yellow birch had higher growth rates, biomass allocation to branches and leaf physiological plasticity and lower crown morphological plasticity in unmodified understory light than sugar maple. Sugar maple did not display significant physiological plasticity, but showed variation with tree size in both crown morphology and whole-tree biomass allocation. When sugar maple was small, a greater proportion of whole-tree biomass was allocated to roots. However, physiological differences between the species decreased with decreasing light and most morphological and allocational differences tended to disappear with increasing tree size, suggesting that many species differences in shade-tolerance are expressed mainly during the seedling stage. Understory trees of both species survived for 4 years under shade nets, possibly because of higher plasticity when small and the use of stored reserves when taller. Copyright 2004 Heron Publishing

Effect of removal of hesperis matronalis (Dame's rocket) on species cover of forest understory vegetation in NW indiana

Science.gov (United States)

Pavlovic, N.B.; Leicht-Young, S. A.; Frohnapple, K.J.; Grundel, R.

2009-01-01

Exotic invasive plant species differ in their effects on indigenous vegetation as evidenced by research evaluating community response to their removal. We used a removal approach to quantify the response of a mesic woodland to the removal versus retention of an invasive plant, Hesperis matronalis (dame's rocket) from paired treatment plots over 3 y. Cover of H. matronalis did not differ between control and treatment plots prior to removal, declined in the removal plots and remained significantly lower in cover compared to the control plots. Removal did not significantly affect species richness and species diversity (evenness, Shannon and Simpson) at the plot scale, but did result in increased species richness overall in the removal plots in the last sampling year when compared to control plots. Non-metric multidimensional scaling ordination analysis indicated a significant compositional change in the spring plant composition of plots over the 3 y, reflecting an increase in exotic woody species. Exotic woody plants, especially Rosa multiflora and Euonymus alatus, increased in cover in response to H. matronalis removal. In the 3 y, neither native nor exotic forbs, nor native woody plants responded to the removal of H. matronalis in a statistically significant manner. The increasing cover of woody invasive plants in response to the removal of H. matronalis has important management implications for restoration of degraded communities.

Woody riparian vegetation response to different alluvial water table regimes

Science.gov (United States)

Shafroth, P.B.; Stromberg, J.C.; Patten, D.T.

2000-01-01

Woody riparian vegetation in western North American riparian ecosystems is commonly dependent on alluvial groundwater. Various natural and anthropogenic mechanisms can cause groundwater declines that stress riparian vegetation, but little quantitative information exists on the nature of plant response to different magnitudes, rates, and durations of groundwater decline. We observed groundwater dynamics and the response of Populus fremontii, Salix gooddingii, and Tamarix ramosissima saplings at 3 sites between 1995 and 1997 along the Bill Williams River, Arizona. At a site where the lowest observed groundwater level in 1996 (-1.97 m) was 1.11 m lower than that in 1995 (-0.86 m), 92-100% of Populus and Salix saplings died, whereas 0-13% of Tamarix stems died. A site with greater absolute water table depths in 1996 (-2.55 m), but less change from the 1995 condition (0.55 m), showed less Populus and Salix mortality and increased basal area. Excavations of sapling roots suggest that root distribution is related to groundwater history. Therefore, a decline in water table relative to the condition under which roots developed may strand plant roots where they cannot obtain sufficient moisture. Plant response is likely mediated by other factors such as soil texture and stratigraphy, availability of precipitation-derived soil moisture, physiological and morphological adaptations to water stress, and tree age. An understanding of the relationships between water table declines and plant response may enable land and water managers to avoid activities that are likely to stress desirable riparian vegetation.

Effects of experimental nitrogen additions on plant diversity in tropical forests of contrasting disturbance regimes in southern China

International Nuclear Information System (INIS)

Lu Xiankai; Mo Jiangming; Gilliam, Frank S.; Yu Guirui; Zhang Wei; Fang Yunting; Huang Juan

2011-01-01

Responses of understory plant diversity to nitrogen (N) additions were investigated in reforested forests of contrasting disturbance regimes in southern China from 2003 to 2008: disturbed forest (with harvesting of understory vegetation and litter) and rehabilitated forest (without harvesting). Experimental additions of N were administered as the following treatments: Control, 50 kg N ha -1 yr -1 , and 100 kg N ha -1 yr -1 . Nitrogen additions did not significantly affect understory plant richness, density, and cover in the disturbed forest. Similarly, no significant response was found for canopy closure in this forest. In the rehabilitated forest, species richness and density showed no significant response to N additions; however, understory cover decreased significantly in the N-treated plots, largely a function of a significant increase in canopy closure. Our results suggest that responses of plant diversity to N deposition may vary with different land-use history, and rehabilitated forests may be more sensitive to N deposition. - Highlights: → Nitrogen addition had no significant effect on understory plant diversity in the disturbed forest. → Nitrogen addition significantly decreased understory plant cover. → Nitrogen addition had no effect on richness and density in the rehabilitated forest. → The decrease is largely a function of a significant increase in canopy closure. → Land-use practices may dominate the responses of plant diversity to N addition. - Research in disturbed forests of southeastern China demonstrates that land-use history can substantially alter effects of excess nitrogen deposition on plant diversity of tropical forest ecosystems.

Stable oxygen isotope analysis reveal vegetation influence on soil water movement and ecosystem water fluxes in a semi-arid oak woodland

Science.gov (United States)

Piayda, Arndt; Dubbert, Maren; Werner, Christiane; Cuntz, Matthias

2015-04-01

Mechanistically disentangling the role and function of vegetation within the hydrological cycle is one of the key questions in the interdisciplinary field of ecohydrology. The presence of vegetation can have various impacts on soil water relations: transpiration of active vegetation causes great water losses, rainfall is intercepted, soil evaporation can be reduced and infiltration, hydraulic redistribution and translatory flow might be altered. In drylands, covering around 40% of the global land surface, the carbon cycle is closely coupled to water availability due to (seasonal) droughts. Specifically savannah type ecosystems, which cover large areas worldwide, are, due to their bi-layered structure, very suitable to study the effects of distinct vegetation types on the ecosystem water cycle. Oxygen isotope signatures (δ18O) have been used to partition ecosystem evapotranspiration (ET ) because of the distinct isotopic compositions of water transpired by leaves relative to soil evaporated vapor. Recent developments in laser spectroscopy enable measurements of δ18O in the vapor phase with high temporal resolution in the field and bear a novel opportunity to trace water movement within the ecosystem. In the present study, the effects of distinct vegetation layers (i.e. trees and herbaceous vegetation) on soil water infiltration and redistribution as well as ecosystem water fluxes in a Mediterranean cork-oak woodland are disentangled. An irrigation experiment was carried out using δ18O labeled water to quantify the distinct effects of trees and herbaceous vegetation on 1) infiltration and redistribution of water in the soil profile and 2) to disentangle the effects of tree cover on the contribution of unproductive soil evaporation and understory transpiration to total ET . First results proof that stable δ18O isotopes measured onsite with laser spectroscopy is a valuable tool to trace water movement in the soil showing a much higher sensitivity than common TDR

Songbird response to alternative forest density management in young Douglas-fir stands

Science.gov (United States)

Joan C. Hagar

2013-01-01

Th inning has been increasingly used in the Pacifi c Northwest to restore structural and biological diversity to densely-stocked young- to mid-aged forests that have been previously intensively managed for timber production. In the short term, thinning promotes development of understory vegetation, which in turn can increase habitat diversity for wildlife, particularly...

Evapotranspiration patterns in complex upland forests reveal contrasting topographic thresholds of non-linearity

Science.gov (United States)

Metzen, D.; Sheridan, G. J.; Benyon, R. G.; Bolstad, P. V.; Nyman, P.; Lane, P. N. J.

2017-12-01

Large areas of forest are often treated as being homogeneous just because they fall in a single climate category. However, we observe strong vegetation patterns in relation to topography in SE Australian forests and thus hypothesise that ET will vary spatially as well. Spatial heterogeneity evolves over different temporal scales in response to climatic forcing with increasing time lag from soil moisture (sub-yearly), to vegetation (10s -100s of years) to soil properties and topography (>100s of years). Most importantly, these processes and time scales are not independent, creating feedbacks that result in "co-evolved stable states" which yield the current spatial terrain, vegetation and ET patterns. We used up-scaled sap flux and understory ET measurements from water-balance plots, as well as LiDAR derived terrain and vegetation information, to infer links between spatio-temporal energy and water fluxes, topography and vegetation patterns at small catchment scale. Topography caused variations in aridity index between polar and equatorial-facing slopes (1.3 vs 1.8), which in turn manifested in significant differences in sapwood area index (6.9 vs 5.8), overstory LAI (3.0 vs 2.3), understory LAI (0.5 vs 0.4), sub-canopy radiation load (4.6 vs 6.8 MJ m-2 d-1), overstory transpiration (501 vs 347 mm a-1) and understory ET (79 vs 155 mm a-1). Large spatial variation in overstory transpiration (195 to 891 mm a-1) was observed over very short distances (100s m); a range representative of diverse forests such as arid open woodlands and wet mountain ash forests. Contrasting, non-linear overstory and understory ET patterns were unveiled between aspects, and topographic thresholds were lower for overstory than understory ET. While ET partitioning remained stable on polar-facing slopes regardless of slope position, overstory contribution gradually decreased with increasing slope inclination on equatorial aspects. Further, we show that ET patterns and controls underlie strong

Site quality influence over understory plant diversity in old-growth and harvested Nothofagus pumilio forests

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E. A. Gallo

2013-04-01

Full Text Available Aim of study: The effects and interactions of shelterwood forest harvesting and site qualities over understory plant species diversity and composition were compared among primary and harvested Nothofagus pumilio forests.Area of study: Tierra del Fuego (Argentina, on three pure conditions (one and six year-old harvested, and primary without previous harvesting forests and three site qualities (high, medium and low.Material and Methods: Understory richness and cover (% were registered in five replicates of 1 hectare each per treatment. Taxonomic species were classified in categories (groups, origin and life forms. Two-way ANOVAs and multivariate analyses were conducted.Main results: Shelterwood harvesting and site quality significantly influenced understory cover and richness, which allow the introduction of native and exotic species and increasing of dicot and monocot covers. In dicots, monocots, exotics and total groups, higher richness and covers were related to time. Meanwhile, cover reached similar high values in all site qualities on dicot, native and total groups. On the other hand, monocot and exotic richness and cover remain similar in primary and recently harvested forests, and greatly increased in old harvested forests. Mosses and ferns were among the most sensitive groups.Research highlights: Impacts of shelterwood cut depend on site quality of the stands and time since harvesting occurs. For this, different site quality stands should received differential attention in the development of conservation strategies, as well as variations in the shelterwood implementation (as irregularity and patchiness should be considered to better promote understory plant species conservation inside managed areas.Key words: plant species conservation; years after harvesting; forest management; Tierra del Fuego.

Radionuclide Concentrations in soils an Vegetation at Low-Level Radioactive Waste Disposal Area G During 2004

Energy Technology Data Exchange (ETDEWEB)

P.R. Fresquez; E.A. Lopez

2004-11-01

Soil samples were collected at 15 locations and unwashed overstory and understory vegetation samples were collected at nine locations within and around the perimeter of Area G, the primary disposal facility for low-level radioactive solid waste at Los Alamos National Laboratory (LANL). These samples were analyzed for {sup 3}H, {sup 238}Pu, {sup 239,240}Pu, {sup 90}Sr, {sup 241}Am, {sup 137}Cs, {sup 234}U, {sup 235}U, and {sup 238}U. Soil samples collected at Area G contained detectable concentrations of 3H (27%), {sup 239,240}Pu (60%), {sup 238}Pu (40%), and {sup 241}Am (47%) above regional statistical reference levels (RSRLs). In contrast, the levels of {sup 137}Cs, {sup 90}Sr, and U in all of the soil samples at Area G were either nondetectable or within RSRLs. The highest levels of {sup 3}H in soils were detected in the southwestern portion of Area G near the {sup 3}H shafts, whereas the highest concentrations of the Pu isotopes were detected in the northern and northeastern portions. All concentrations of {sup 3}H and Pu in soils, however, were far below LANL screening action levels. As for vegetation, most radionuclides in/on plants were either nondetectable or within RSRLs. The exceptions were {sup 3}H in overstory and some understory vegetation, particularly in the southwestern portion of Area G, which correlated very well with the soils data in that area. Also, there was some foliar contamination from {sup 241}Am and Pu isotopes in/on a few plant samples--the highest concentrations occurring in the northern section of Area G.

Response of Sesamum radiatum Schum vegetable and seed yield ...

African Journals Online (AJOL)

Response of Sesamum radiatum Schum vegetable and seed yield to phosphorus ... Western region of Nigeria and Research Farm of the Bio-fuel and Alternate ... that 90 kg P2O5 ha-1 was appropriate with basal application of 80 kg N ha-1.

Unique competitive effects of lianas and trees in a tropical forest understory.

Science.gov (United States)

Wright, Alexandra; Tobin, Mike; Mangan, Scott; Schnitzer, Stefan A

2015-02-01

Lianas are an important component of tropical forests, contributing up to 25% of the woody stems and 35% of woody species diversity. Lianas invest less in structural support but more in leaves compared to trees of similar biomass. These physiological and morphological differences suggest that lianas may interact with neighboring plants in ways that are different from similarly sized trees. However, the vast majority of past liana competition studies have failed to identify the unique competitive effects of lianas by controlling for the amount of biomass removed. We assessed liana competition in the forest understory over the course of 3 years by removing liana biomass and an equal amount of tree biomass in 40 plots at 10 sites in a secondary tropical moist forest in central Panama. We found that growth of understory trees and lianas, as well as planted seedlings, was limited due to competitive effects from both lianas and trees, though the competitive impacts varied by species, season, and size of neighbors. The removal of trees resulted in greater survival of planted seedlings compared to the removal of lianas, apparently related to a greater release from competition for light. In contrast, lianas had a species-specific negative effect on drought-tolerant Dipteryx oleifera seedlings during the dry season, potentially due to competition for water. We conclude that, at local scales, lianas and trees have unique and differential effects on understory dynamics, with lianas potentially competing more strongly during the dry season, and trees competing more strongly for light.

Baseline concentrations of radionuclides and heavy metals in soils and vegetation around the DARHT facility: Construction phase (1996)

International Nuclear Information System (INIS)

Fresquez, P.R.; Haagenstad, H.T.; Naranjo, L. Jr.

1997-04-01

As part of the Department of Energy's Mitigation Action Plan for the Dual Axis Radiographic Hydrodynamic Test (DARHT) Facility at Los Alamos National Laboratory (LANL), baseline concentrations of radionuclides ( 3 H, 137 Cs, 90 Sr, 238 Pu, 239 Pu, 241 Am, total U), and heavy metals (Ag, As, Ba, Be, Cd, Cr, Cu, Hg, Ni, Pb, Sb, Se and Tl) in soil, sediment, and vegetation (overstory and understory) around the DARHT facility during the construction phase in 1996 were determined. Also, U and Be concentrations in soil samples collected in 1993 from within the proposed DARHT facility area are reported. Most radionuclides in soils, sediments, and vegetation were within current background and/or long-term regional statistical reference levels

Vegetation survey of Pen Branch and Four Mile Creek wetlands

Energy Technology Data Exchange (ETDEWEB)

1992-01-01

One hundred-fifty plots were recently sampled (vegetational sampling study) at the Savannah River Site (SRS). An extensive characterization of the vascular flora, in four predetermined strata (overstory, Understory, shrub layer, and ground cover), was undertaken to determine dominance, co-dominance, and the importance value (I.V.) of each species. These results will be used by the Savannah River Laboratory (SRL) to evaluate the environmental status of Four Mile Creek, Pen Branch, and two upland pine stands. Objectives of this study were to: Describe in detail the plant communities previously mapped with reference to the topography and drainage, including species of plants present: Examine the successional trends within each sampling area and describe the extent to which current vegetation communities have resulted from specific earlier vegetation disturbances (e.g., logging and grazing); describe in detail the botanical field techniques used to sample the flora; describe the habitat and location of protected and/or rare species of plants; and collect and prepare plant species as herbarium quality specimens. Sampling was conducted at Four Mile Creek and Pen Branch, and in two upland pine plantations of different age growth.

Vegetation survey of Pen Branch and Four Mile Creek wetlands

Energy Technology Data Exchange (ETDEWEB)

1992-10-01

One hundred-fifty plots were recently sampled (vegetational sampling study) at the Savannah River Site (SRS). An extensive characterization of the vascular flora, in four predetermined strata (overstory, Understory, shrub layer, and ground cover), was undertaken to determine dominance, co-dominance, and the importance value (I.V.) of each species. These results will be used by the Savannah River Laboratory (SRL) to evaluate the environmental status of Four Mile Creek, Pen Branch, and two upland pine stands. Objectives of this study were to: Describe in detail the plant communities previously mapped with reference to the topography and drainage, including species of plants present: Examine the successional trends within each sampling area and describe the extent to which current vegetation communities have resulted from specific earlier vegetation disturbances (e.g., logging and grazing); describe in detail the botanical field techniques used to sample the flora; describe the habitat and location of protected and/or rare species of plants; and collect and prepare plant species as herbarium quality specimens. Sampling was conducted at Four Mile Creek and Pen Branch, and in two upland pine plantations of different age growth.

The legacy of deer overabundance: long-term delays in herbaceous understory recovery

Science.gov (United States)

Thomas H. Pendergast; Shane M. Hanlon; Zachary M. Long; Alex Royo; Walter P. Carson

2016-01-01

Decades of white-tailed deer (Odocoileus virginianus (Zimmermann, 1780)) overpopulation have dramatically homogenized forests across much of the eastern United States, creating depauperate forest understory communities. The rate at which these communities recover once deer browsing has been reduced remains an open question. We evaluate overbrowsing...

Determining relative contributions of vegetation and topography to burn severity from LANDSAT imagery.

Science.gov (United States)

Wu, Zhiwei; He, Hong S; Liang, Yu; Cai, Longyan; Lewis, Bernard J

2013-10-01

Fire is a dominant process in boreal forest landscapes and creates a spatial patch mosaic with different burn severities and age classes. Quantifying effects of vegetation and topography on burn severity provides a scientific basis on which forest fire management plans are developed to reduce catastrophic fires. However, the relative contribution of vegetation and topography to burn severity is highly debated especially under extreme weather conditions. In this study, we hypothesized that relationships of vegetation and topography to burn severity vary with fire size. We examined this hypothesis in a boreal forest landscape of northeastern China by computing the burn severity of 24 fire patches as the difference between the pre- and post-fire Normalized Difference Vegetation Index obtained from two Landsat TM images. The vegetation and topography to burn severity relationships were evaluated at three fire-size levels of small (1,000 ha, n = 3). Our results showed that vegetation and topography to burn severity relationships were fire-size-dependent. The burn severity of small fires was primary controlled by vegetation conditions (e.g., understory cover), and the burn severity of large fires was strongly influenced by topographic conditions (e.g., elevation). For moderate fires, the relationships were complex and indistinguishable. Our results also indicated that the pattern trends of relative importance for both vegetation and topography factors were not dependent on fire size. Our study can help managers to design fire management plans according to vegetation characteristics that are found important in controlling burn severity and prioritize management locations based on the relative importance of vegetation and topography.

A Phenology-Based Method for Monitoring Woody and Herbaceous Vegetation in Mediterranean Forests from NDVI Time Series

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David Helman

2015-09-01

Full Text Available We present an efficient method for monitoring woody (i.e., evergreen and herbaceous (i.e., ephemeral vegetation in Mediterranean forests at a sub pixel scale from Normalized Difference Vegetation Index (NDVI time series derived from the Moderate Resolution Imaging Spectroradiometer (MODIS. The method is based on the distinct development periods of those vegetation components. In the dry season, herbaceous vegetation is absent or completely dry in Mediterranean forests. Thus the mean NDVI in the dry season was attributed to the woody vegetation (NDVIW. A constant NDVI value was assumed for soil background during this period. In the wet season, changes in NDVI were attributed to the development of ephemeral herbaceous vegetation in the forest floor and its maximum value to the peak green cover (NDVIH. NDVIW and NDVIH agreed well with field estimates of leaf area index and fraction of vegetation cover in two differently structured Mediterranean forests. To further assess the method’s assumptions, understory NDVI was retrieved form MODIS Bidirectional Reflectance Distribution Function (BRDF data and compared with NDVIH. After calibration, leaf area index and woody and herbaceous vegetation covers were assessed for those forests. Applicability for pre- and post-fire monitoring is presented as a potential use of this method for forest management in Mediterranean-climate regions.

Responses of selected biota after biostimulation of a vegetable oil ...

African Journals Online (AJOL)

Responses of selected biota after biostimulation of a vegetable oil spill in the Con Joubert Bird Sanctuary wetland: A pilot study. Mapurunyane C Selala, Paul J Oberholster, Karen AK Surridge, Arno R de Klerk, Anna-Maria Botha ...

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~...

Monitoring shifts in plant diversity in response to climate change: A method for landscapes

Science.gov (United States)

Stohlgren, T.J.; Owen, A.J.; Lee, M.

2000-01-01

Improved sampling designs are needed to detect, monitor, and predict plant migrations and plant diversity changes caused by climate change and other human activities. We propose a methodology based on multi-scale vegetation plots established across forest ecotones which provide baseline data on patterns of plant diversity, invasions of exotic plant species, and plant migrations at landscape scales in Rocky Mountain National Park, Colorado, USA. We established forty two 1000-m2 plots in relatively homogeneous forest types and the ecotones between them on 14 vegetation transects. We found that 64% of the variance in understory species distributions at landscape scales were described generally by gradients of elevation and under-canopy solar radiation. Superimposed on broad-scale climatic gradients are small-scale gradients characterized by patches of light, pockets of fertile soil, and zones of high soil moisture. Eighteen of the 42 plots contained at least one exotic species; monitoring exotic plant invasions provides a means to assess changes in native plant diversity and plant migrations. Plant species showed weak affinities to overstory vegetation types, with 43% of the plant species found in three or more vegetation types. Replicate transects along several environmental gradients may provide the means to monitor plant diversity and species migrations at landscape scales because: (1) ecotones may play crucial roles in expanding the geophysiological ranges of many plant species; (2) low affinities of understory species to overstory forest types may predispose vegetation types to be resilient to rapid environmental change; and (3) ecotones may help buffer plant species from extirpation and extinction.

Response of alpine vegetation growth dynamics to snow cover phenology on the Tibetan Plateau

Science.gov (United States)

Wang, X.; Wu, C.

2017-12-01

Alpine vegetation plays a crucial role in global energy cycles with snow cover, an essential component of alpine land cover showing high sensitivity to climate change. The Tibetan Plateau (TP) has a typical alpine vegetation ecosystem and is rich of snow resources. With global warming, the snow of the TP has undergone significant changes that will inevitably affect the growth of alpine vegetation, but observed evidence of such interaction is limited. In particular, a comprehensive understanding of the responses of alpine vegetation growth to snow cover variability is still not well characterized on TP region. To investigate this, we calculated three indicators, the start (SOS) and length (LOS) of growing season, and the maximum of normalized difference vegetation index (NDVImax) as proxies of vegetation growth dynamics from the Moderate Resolution Imaging Spectroradiometer (MODIS) data for 2000-2015. Snow cover duration (SCD) and melt (SCM) dates were also extracted during the same time frame from the combination of MODIS and the Interactive Multi-sensor Snow and Ice Mapping System (IMS) data. We found that the snow cover phenology had a strong control on alpine vegetation growth dynamics. Furthermore, the responses of SOS, LOS and NDVImax to snow cover phenology varied among plant functional types, eco-geographical zones, and temperature and precipitation gradients. The alpine steppes showed a much stronger negative correlation between SOS and SCD, and also a more evidently positive relationship between LOS and SCD than other types, indicating a longer SCD would lead to an earlier SOS and longer LOS. Most areas showed positive correlation between SOS and SCM, while a contrary response was also found in the warm but drier areas. Both SCD and SCM showed positive correlations with NDVImax, but the relationship became weaker with the increase of precipitation. Our findings provided strong evidences between vegetation growth and snow cover phenology, and changes in

Mapping Canopy Damage from Understory Fires in Amazon Forests Using Annual Time Series of Landsat and MODIS Data

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Morton, Douglas C.; DeFries, Ruth S.; Nagol, Jyoteshwar; Souza, Carlos M., Jr.; Kasischke, Eric S.; Hurtt, George C.; Dubayah, Ralph

2011-01-01

Understory fires in Amazon forests alter forest structure, species composition, and the likelihood of future disturbance. The annual extent of fire-damaged forest in Amazonia remains uncertain due to difficulties in separating burning from other types of forest damage in satellite data. We developed a new approach, the Burn Damage and Recovery (BDR) algorithm, to identify fire-related canopy damages using spatial and spectral information from multi-year time series of satellite data. The BDR approach identifies understory fires in intact and logged Amazon forests based on the reduction and recovery of live canopy cover in the years following fire damages and the size and shape of individual understory burn scars. The BDR algorithm was applied to time series of Landsat (1997-2004) and MODIS (2000-2005) data covering one Landsat scene (path/row 226/068) in southern Amazonia and the results were compared to field observations, image-derived burn scars, and independent data on selective logging and deforestation. Landsat resolution was essential for detection of burn scars less than 50 ha, yet these small burns contributed only 12% of all burned forest detected during 1997-2002. MODIS data were suitable for mapping medium (50-500 ha) and large (greater than 500 ha) burn scars that accounted for the majority of all fire-damaged forest in this study. Therefore, moderate resolution satellite data may be suitable to provide estimates of the extent of fire-damaged Amazon forest at a regional scale. In the study region, Landsat-based understory fire damages in 1999 (1508 square kilometers) were an order of magnitude higher than during the 1997-1998 El Nino event (124 square kilometers and 39 square kilometers, respectively), suggesting a different link between climate and understory fires than previously reported for other Amazon regions. The results in this study illustrate the potential to address critical questions concerning climate and fire risk in Amazon forests by

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.

Plant community responses to soil disturbance and herbicide treatments over 10 years on the Texas LTSP study

Science.gov (United States)

D. Andrew Scott; Richard H. Stagg

2013-01-01

Determining how anthropogenic disturbances affect site productivity through bioassays requires a complete understanding of both overstory and understory vegetation. This study was installed in 1997 to determine how soil compaction and intensive harvesting affected the inherent site productivity of pine stands on the western boundary of loblolly pine’s (Pinus...

Western dwarf mistletoe infects understory Jeffrey pine seedlings on Cleveland National Forest, California

Science.gov (United States)

Robert F. Scharpf; Detlev Vogler

1986-01-01

Many young, understory Jeffrey pines (Pinus jeffreyi Grev. & Balf.) were found to be infected by western dwarf mistletoe (Arceuthobium campylopodum Engelm.) on Laguna Mountain, Cleveland National Forest, in southern California. Under heavily infected overstory, about three-fourths of the young pines (about 15 years old on the...

Attempting to restore herbaceous understories in Wyoming big sagebrush communities with mowing and seeding

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Shrub steppe communities with depleted perennial herbaceous understories need to be restored to increase resilience, provide quality wildlife habitat, and improve ecosystem function. Mowing has been applied to Wyoming big sagebrush (Artemisia tridentata Nutt. ssp. wyomingensis Beetle &Young) steppe...

A Database of Herbaceous Vegetation Responses to Elevated Atmospheric CO{sub 2}

Energy Technology Data Exchange (ETDEWEB)

Jones, M.H.

1999-11-24

To perform a statistically rigorous meta-analysis of research results on the response by herbaceous vegetation to increased atmospheric CO{sub 2} levels, a multiparameter database of responses was compiled from the published literature. Seventy-eight independent CO{sub 2}-enrichment studies, covering 53 species and 26 response parameters, reported mean response, sample size, and variance of the response (either as standard deviation or standard error). An additional 43 studies, covering 25 species and 6 response parameters, did not report variances. This numeric data package accompanies the Carbon Dioxide Information Analysis Center's (CDIAC's) NDP-072, which provides similar information for woody vegetation. This numeric data package contains a 30-field data set of CO{sub 2}-exposure experiment responses by herbaceous plants (as both a flat ASCII file and a spreadsheet file), files listing the references to the CO{sub 2}-exposure experiments and specific comments relevant to the data in the data sets, and this documentation file (which includes SAS{reg_sign} and Fortran codes to read the ASCII data file). The data files and this documentation are available without charge on a variety of media and via the Internet from CDIAC.

Seasonality of Overstory and Understory Fluxes in a Semi-Arid Oak Savanna: What can be Learned from Comparing Measured and Modeled Fluxes?

Science.gov (United States)

Raz-Yaseef, N.; Sonnentag, O.; Kobayashi, H.; Chen, J. M.; Verfaillie, J. G.; Ma, S.; Baldocchi, D. D.

2011-12-01

precipitation events, likely produced by an adverse measurement effect. This analysis enabled to pinpoint specific areas where models break, and stress that model capability to reproduce fluxes vary among seasons and ecosystem components. The combined response was such, that comparison decreases when ecosystem fluxes were partitioned between overstory and understory fluxes. Model performance decreases with time scale; while performance was high for some seasons, models were less capable of reproducing the high variability in understory fluxes vs. the conservative overstory fluxes on annual scales. Discrepancies were not always a result of models' faults; comparison largely improved when measurements of overstory fluxes during precipitation events were excluded. Conclusions raised from this research enable to answer the critical question of the level and type of details needed in order to correctly predict ecosystem respond to environmental and climatic change.

Changes in Patterns of Understory Leaf Phenology and Herbivory following Hurricane Damage.

Science.gov (United States)

Pilar Angulo-Sandoval; H. Fernandez-Marin; J. K. Zimmerman; T. M. Aide

2004-01-01

Hurricanes are important disturbance events in many forested ecosystems. They can have strong effects on both forest structure and animal populations, and yet few studies have considered the impacts on plant–animal interactions. Reduction of canopy cover by severe winds increases light availability to understory plants, providing an opportunity for increased growth. An...

Model-generated air quality statistics for application in vegetation response models in Alberta

International Nuclear Information System (INIS)

McVehil, G.E.; Nosal, M.

1990-01-01

To test and apply vegetation response models in Alberta, air pollution statistics representative of various parts of the Province are required. At this time, air quality monitoring data of the requisite accuracy and time resolution are not available for most parts of Alberta. Therefore, there exists a need to develop appropriate air quality statistics. The objectives of the work reported here were to determine the applicability of model generated air quality statistics and to develop by modelling, realistic and representative time series of hourly SO 2 concentrations that could be used to generate the statistics demanded by vegetation response models

Indonesian vegetation response to changes in rainfall seasonality over the past 25,000 years

Science.gov (United States)

Dubois, Nathalie; Oppo, Delia W.; Galy, Valier V.; Mohtadi, Mahyar; van der Kaars, Sander; Tierney, Jessica E.; Rosenthal, Yair; Eglinton, Timothy I.; Lückge, Andreas; Linsley, Braddock K.

2014-07-01

The hydrologic response to climate forcing in the Indo-Pacific warm pool region has varied spatially over the past 25,000 years. For example, drier conditions are inferred on Java and Borneo for the period following the end of the Last Glacial Maximum, whereas wetter conditions are reconstructed for northwest Australia. The response of vegetation to these past rainfall variations is poorly constrained. Using a suite of 30 surface marine sediment samples from throughout the Indo-Pacific warm pool, we demonstrate that today the stable isotopic composition of vascular plant fatty acids (δ13CFA) reflects the regional vegetation composition. This in turn is controlled by the seasonality of rainfall consistent with dry season water stress. Applying this proxy in a sediment core from offshore northeast Borneo, we show broadly similar vegetation cover during the Last Glacial Maximum and the Holocene, suggesting that, despite generally drier glacial conditions, there was no pronounced dry season. In contrast, δ13CFA and pollen data from a core off the coast of Sumba indicate an expansion of C4 herbs during the most recent glaciation, implying enhanced aridity and water stress during the dry season. Holocene vegetation trends are also consistent with a response to dry season water stress. We therefore conclude that vegetation in tropical monsoon regions is susceptible to increases in water stress arising from an enhanced seasonality of rainfall, as has occurred in past decades.

Using MODIS-NDVI for the Modeling of Post-Wildfire Vegetation Response as a Function of Environmental Conditions and Pre-Fire Restoration Treatments

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Grant M. Casady

2012-03-01

Full Text Available Post-fire vegetation response is influenced by the interaction of natural and anthropogenic factors such as topography, climate, vegetation type and restoration practices. Previous research has analyzed the relationship of some of these factors to vegetation response, but few have taken into account the effects of pre-fire restoration practices. We selected three wildfires that occurred in Bandelier National Monument (New Mexico, USA between 1999 and 2007 and three adjacent unburned control areas. We used interannual trends in the Normalized Difference Vegetation Index (NDVI time series data derived from the Moderate Resolution Imaging Spectroradiometer (MODIS to assess vegetation response, which we define as the average potential photosynthetic activity through the summer monsoon. Topography, fire severity and restoration treatment were obtained and used to explain post-fire vegetation response. We applied parametric (Multiple Linear Regressions-MLR and non-parametric tests (Classification and Regression Trees-CART to analyze effects of fire severity, terrain and pre-fire restoration treatments (variable used in CART on post-fire vegetation response. MLR results showed strong relationships between vegetation response and environmental factors (p < 0.1, however the explanatory factors changed among treatments. CART results showed that beside fire severity and topography, pre-fire treatments strongly impact post-fire vegetation response. Results for these three fires show that pre-fire restoration conditions along with local environmental factors constitute key processes that modify post-fire vegetation response.

Understanding patterns of vegetation structure and distribution across Great Smoky Mountains National Park using LiDAR and meteorology data

Science.gov (United States)

Kumar, J.; Hargrove, W. W.; Norman, S. P.; Hoffman, F. M.

2017-12-01

Great Smoky Mountains National Park (GSMNP) in Tennessee is a biodiversity hotspot and home to a large number of plant, animal and bird species. Driven by gradients of climate (ex. temperature, precipitation regimes), topography (ex. elevation, slope, aspect), geology (ex. soil types, textures, depth), hydrology (ex. drainage, moisture availability) etc. GSMNP offers a diverse composition and distribution of vegetation which in turn supports an array of wildlife. Understanding the vegetation canopy structure is critical to understand, monitor and manage the complex forest ecosystems like the Great Smoky Mountain National Park (GSMNP). Vegetation canopies not only help understand the vegetation, but are also a critically important habitat characteristics of many threatened and endangered animal and bird species that GSMNP is home to. Using airborne Light Detection and Ranging (LiDAR) we characterize the three-dimensional structure of the vegetation. LiDAR based analysis gives detailed insight in the canopy structure (overstory and understory) and its spatial variability within and across forest types. Vegetation structure and spatial distribution show strong correlation with climate, topographic, and edaphic variables and our multivariate analysis not just mines rich and large LiDAR data but presents ecological insights and data for vegetation within the park that can be useful to forest managers in their management and conservation efforts.

Forest Understory Fire in the Brazilian Amazon in ENSO and Non-ENSO Years: Area Burned and Committed Carbon Emissions

Science.gov (United States)

Alencar, A.; Nepstad, D.; Ver-Diaz, M. Del. C.

2004-01-01

"Understory fires" that burn the floor of standing forests are one of the most important types of forest impoverishment in the Amazon, especially during the severe droughts of El Nino Southern Oscillation (ENSO) episodes. However, we are aware of no estimates of the areal extent of these fires for the Brazilian Amazon and, hence, of their contribution to Amazon carbon fluxes to the atmosphere. We calculated the area of forest understory fires for the Brazilian Amazon region during an El Nino (1998) and a non El Nino (1995) year based on forest fire scars mapped with satellite images for three locations in eastern and southern Amazon, where deforestation is concentrated. The three study sites represented a gradient of both forest types and dry season severity. The burning scar maps were used to determine how the percentage of forest that burned varied with distance from agricultural clearings. These spatial functions were then applied to similar forest/climate combinations outside of the study sites to derive an initial estimate for the Brazilian Amazon. Ninety-one percent of the forest area that burned in the study sites was within the first kilometer of a clearing for the non ENSO year and within the first four kilometers for the ENSO year. The area of forest burned by understory forest fire during the severe drought (ENSO) year (3.9 millions of hectares) was 13 times greater than the area burned during the average rainfall year (0.2 million hectares), and twice the area of annual deforestation rate. Dense forest was, proportionally, the forest area most affected by understory fires during the El Nino year, while understory fires were concentrated in transitional forests during the year of average rainfall. Our estimate of aboveground tree biomass killed by fire ranged from 0.06 Pg to 0.38 Pg during the ENSO and from 0,004 Pg to 0,024 Pg during the non ENSO.

Examining Severe Drought-Induced Vegetation Change and its Influence on Water Resources

Science.gov (United States)

White, A. B.; Springer, E. P.; Vivoni, E. R.

2007-12-01

A "global-change-type" drought that occurred in the southwestern U.S. from 2000 to 2003, accompanied by increased temperatures and bark beetle infestations, induced large-scale woodland overstory mortality, the consequent redistribution of water, radiation, and nutrients, as well as modification of the ecosystem phenology. Our objectives in this research are to examine these vegetation changes in detail and to determine whether they translated to changes in hydrological processes. We chose the Rio Ojo Caliente, a subbasin of the Rio Grande, as a study site since a significant portion of the woodland ecosystem (piñon-juniper) was affected. Examining a remotely-sensed vegetation index (1-km AVHRR NDVI from 1989 to 2006), there is an increasing trend in the mean NDVI from 1989 to 1998 (pre-drought period), a decreasing trend from 1999 to 2003 (drought period), and a dramatic increasing trend from 2004 to 2006 (post-drought period) in which the mean NDVI rebounds to pre- drought magnitudes. Streamflow records from 1932 to 2006 show the watershed to be primarily spring snowmelt-driven, although monsoonal summer precipitation also plays a significant role. We compare the temporal variability in the streamflow to the NDVI, including the mean, anomalies from the mean, and seasonally- based duration curves, and find significant correlations (correlation coefficient ρ = -0.61) between the streamflow and NDVI at approximately a three-month lag (NDVI lagging streamflow). In analyzing the three phases of the drought, the correlation is slightly stronger during the pre-drought (ρ = -0.64) and drought (ρ = -0.65) periods, yet markedly stronger during the post-drought period (ρ = -0.74). This suggests that the coupling between vegetation water use and streamflow is tighter after the drought. This may be attributable to the reduction in the less-responsive overstory (pinñon mortality) and increase in the more-responsive understory (grasses and shrubs exploiting newly

Long-term vegetation changes in a temperate forest impacted by climate change

Science.gov (United States)

Lauren E. Oakes; Paul E. Hennon; Kevin L. O' Hara; Rodolfo Dirzo

2014-01-01

Pervasive forest mortality is expected to increase in future decades as a result of increasing temperatures. Climate-induced forest dieback can have consequences on ecosystem services, potentially mediated by changes in forest structure and understory community composition that emerge in response to tree death. Although many dieback events around the world have been...

Response of spatial vegetation distribution in China to climate changes since the Last Glacial Maximum (LGM)

Science.gov (United States)

Wang, Siyang; Xu, Xiaoting; Shrestha, Nawal; Zimmermann, Niklaus E.; Tang, Zhiyao; Wang, Zhiheng

2017-01-01

Analyzing how climate change affects vegetation distribution is one of the central issues of global change ecology as this has important implications for the carbon budget of terrestrial vegetation. Mapping vegetation distribution under historical climate scenarios is essential for understanding the response of vegetation distribution to future climatic changes. The reconstructions of palaeovegetation based on pollen data provide a useful method to understand the relationship between climate and vegetation distribution. However, this method is limited in time and space. Here, using species distribution model (SDM) approaches, we explored the climatic determinants of contemporary vegetation distribution and reconstructed the distribution of Chinese vegetation during the Last Glacial Maximum (LGM, 18,000 14C yr BP) and Middle-Holocene (MH, 6000 14C yr BP). The dynamics of vegetation distribution since the LGM reconstructed by SDMs were largely consistent with those based on pollen data, suggesting that the SDM approach is a useful tool for studying historical vegetation dynamics and its response to climate change across time and space. Comparison between the modeled contemporary potential natural vegetation distribution and the observed contemporary distribution suggests that temperate deciduous forests, subtropical evergreen broadleaf forests, temperate deciduous shrublands and temperate steppe have low range fillings and are strongly influenced by human activities. In general, the Tibetan Plateau, North and Northeast China, and the areas near the 30°N in Central and Southeast China appeared to have experienced the highest turnover in vegetation due to climate change from the LGM to the present. PMID:28426780

Fine-spatial scale predictions of understory species using climate- and LiDAR-derived terrain and canopy metrics

Science.gov (United States)

Nijland, Wiebe; Nielsen, Scott E.; Coops, Nicholas C.; Wulder, Michael A.; Stenhouse, Gordon B.

2014-01-01

Food and habitat resources are critical components of wildlife management and conservation efforts. The grizzly bear (Ursus arctos) has diverse diets and habitat requirements particularly for understory plant species, which are impacted by human developments and forest management activities. We use light detection and ranging (LiDAR) data to predict the occurrence of 14 understory plant species relevant to bear forage and compare our predictions with more conventional climate- and land cover-based models. We use boosted regression trees to model each of the 14 understory species across 4435 km2 using occurrence (presence-absence) data from 1941 field plots. Three sets of models were fitted: climate only, climate and basic land and forest covers from Landsat 30-m imagery, and a climate- and LiDAR-derived model describing both the terrain and forest canopy. Resulting model accuracies varied widely among species. Overall, 8 of 14 species models were improved by including the LiDAR-derived variables. For climate-only models, mean annual precipitation and frost-free periods were the most important variables. With inclusion of LiDAR-derived attributes, depth-to-water table, terrain-intercepted annual radiation, and elevation were most often selected. This suggests that fine-scale terrain conditions affect the distribution of the studied species more than canopy conditions.

Extension of virtual flux decomposition model to the case of two vegetation layers: FDM-2

International Nuclear Information System (INIS)

Kallel, Abdelaziz

2012-01-01

As an approximation, the forest could be assumed a discrete media composed of three main components: trees, understory vegetation and soil background. To describe the reflectance of such a canopy in the optical wavelength domain, it is necessary to develop a radiative transfer model which considers two vegetation layers (understory and trees). In this article, we propose a new model, FDM-2, an extension of the flux decomposition model (FDM), to take into account such a canopy architecture. Like FDM, FDM-2 models the diffuse flux anisotropy and takes into account the hot spot effect as well as conserves energy. The hot spot which corresponds to an increase of the probability of photon escape after first collision close to the backscattering direction is modeled as a decrease of “the effective vegetation density” encountered by the diffuse flux (E + 1 ) and the radiance both created by first order scattering of the direct sun radiation. Compared to the turbid case (for which our model is equivalent to SAIL++ and therefore accurately conserving energy), such a density variation redistributes energy but does not affect the budget. Energy remains well conserved in the discrete case as well. To solve the RT problem, FDM-2 separates E + 1 from the high order diffuse flux. As E + 1 corresponding effective density is not constant function of the altitude (when traveling along the canopy) therefore it is decomposed into sub-fluxes of constant densities. The sub-flux RT problems are linear and simply solved based on SAIL++ formalism. The global RT solution is obtained summing the contribution of the sub-fluxes. Simulation tests confirm that FDM-2 conserves energy (i.e., radiative budget closes to zero in the purist corner case with an error due to the discretization less than 0.5%). Compared to the Rayspread model (among the best 3-D models of the RAMI Exercise third phase), our model provides similar performance.

Holocene fire activity and vegetation response in South-Eastern Iberia

Science.gov (United States)

Gil-Romera, Graciela; Carrión, José S.; Pausas, Juli G.; Sevilla-Callejo, Miguel; Lamb, Henry F.; Fernández, Santiago; Burjachs, Francesc

2010-05-01

Since fire has been recognized as an essential disturbance in Mediterranean landscapes, the study of long-term fire ecology has developed rapidly. We have reconstructed a sequence of vegetation dynamics and fire changes across south-eastern Iberia by coupling records of climate, fire, vegetation and human activities. We calculated fire activity anomalies (FAAs) in relation to 3 ka cal BP for 10-8 ka cal BP, 6 ka cal BP, 4 ka cal BP and the present. For most of the Early to the Mid-Holocene uneven, but low fire events were the main vegetation driver at high altitudes where broadleaved and coniferous trees presented a highly dynamic post-fire response. At mid-altitudes in the mainland Segura Mountains, fire activity remained relatively stable, at similar levels to recent times. We hypothesize that coastal areas, both mountains and lowlands, were more fire-prone landscapes as biomass was more likely to have accumulated than in the inland regions, triggering regular fire events. The wet and warm phase towards the Mid-Holocene (between ca 8 and 6 ka cal BP) affected the whole region and promoted the spread of mesophytic forest co-existing with Pinus, as FAAs appear strongly negative at 6 ka cal BP, with a less important role of fire. Mid and Late Holocene landscapes were shaped by an increasing aridity trend and the rise of human occupation, especially in the coastal mountains where forest disappeared from ca 2 ka cal BP. Mediterranean-type vegetation (evergreen oaks and Pinus pinaster- halepensis types) showed the fastest post-fire vegetation dynamics over time.

Influence of vegetable diets on physiological and immune responses to thermal stress in Senegalese sole (Solea senegalensis)

DEFF Research Database (Denmark)

Conde-Sieira, Marta; Gesto, Manuel; Batista, Sónia

2018-01-01

quality parameters. However, scarce information is available regarding the long-term impact of vegetable diets (combining the inclusion of both vegetable protein and oils) on the stress response and immunity of this fish species. This study aims to evaluate the concomitant effect of the extended use...... of vegetable protein-based diets with fish oil (FO) replacement (0, 50 or 100%) by vegetable oils (VO), on the response to acute (10 min) or prolonged (4 days) stress, induced by thermal shock. Plasma levels of cortisol, glucose and lactate as well as hepatic levels of glucose, glycogen and lactate were......The substitution of fish resources as ingredients for aquafeeds by those based on vegetable sources is needed to ensure aquaculture sustainability in the future. It is known that Senegalese sole (Solea senegalensis) accepts high dietary content of plant ingredients without altering growth or flesh...

Understory plant diversity in riparian alder-conifer stands after logging in southeast Alaska.

Science.gov (United States)

Robert L. Deal

1997-01-01

Stand structure, tree height growth, and understory plant diversity were assessed in five mixed alder-conifer stands after logging in southeast Alaska. Tree species composition ranged from 7- to 91-percent alder, and basal area ranged from 30 to 55 m2/ha. The alder exhibited rapid early height growth, but recent growth has slowed considerably. Some conifers have...

Fruit and vegetables consumption and incident hypertension: dose-response meta-analysis of prospective cohort studies.

Science.gov (United States)

Wu, L; Sun, D; He, Y

2016-10-01

The role of dietary factors on chronic diseases seems essential in the potentially adverse or preventive effects. However, no evidence of dose-response meta-analysis of prospective cohort studies has verified the association between the intake of fruit and/or vegetables and the risk of developing hypertension. The PubMed and Embase were searched for prospective cohort studies. A generic inverse-variance method with random effects model was used to calculate the pooled relative risks (RRs) and 95% confidence intervals (CIs). Generalized least squares trend estimation model was used to calculate the study-specific slopes for the dose-response analyses. Seven articles comprised nine cohorts involving 185 676 participants were assessed. The highest intake of fruit or vegetables separately, and total fruit and vegetables were inversely associated with the incident risk of hypertension compared with the lowest level, and the pooled RRs and 95% CIs were 0.87 (0.79, 0.95), 0.88 (0.79, 0.99) and 0.90 (0.84, 0.98), respectively. We also found an inverse dose-response relation between the risk of developing hypertension and fruit intake, and total fruit and vegetables consumption. The incident risk of hypertension was decreased by 1.9% for each serving per day of fruit consumption, and decreased by 1.2% for each serving per day of total fruit and vegetables consumption. Our results support the recommendation to increase the consumption of fruit and vegetables with respect to preventing the risk of developing hypertension. However, further large prospective studies and long-term high-quality randomized controlled trials are still needed to confirm the observed association.

Contrasts between bryophyte and vascular plant synecological responses in an SO/sub 2/-stressed white spruce association in Central Alberta

Energy Technology Data Exchange (ETDEWEB)

Winner, W.E.; Bewley, J.D.

1978-01-01

Canopy coverage analysis was used to examine the synecological changes exhibited by vascular plants and terrestrial mosses in a white spruce association exposed to SO/sub 2/ fumigation. Both these understory components were found to decline in coverage as SO/sub 2/ stress increased, but mosses were more sensitive to SO/sub 2/ in the more heavily stressed areas. This was observed along both an angle-dependent and a distance-dependent gradient of pollution stress. Diversity steadily declined with increasing SO/sub 2/ stress along the angle-dependent gradient but some localized increases in diversity occurred with increasing stress along the distance-dependent gradient. This was due to invasion of openings resulting from attrition of SO/sub 2/-sensitive species by weedy angiosperms and by vegetative growth of moss species more tolerant of pollution stress. Conclusions have been drawn about the productive strategy of vascular plants and mosses subjected to increasing concentrations of SO/sub 2/. We have elucidated the ecological consequences for community structure of the systematic removal of pollution-sensitive understory species from an otherwise stable vegetation unit.

Response of vegetation phenology to urbanization in the conterminous United States

Energy Technology Data Exchange (ETDEWEB)

Li, Xuecao [Department of Geological and Atmospheric Sciences, Iowa State University, Ames IA 50011 USA; Zhou, Yuyu [Department of Geological and Atmospheric Sciences, Iowa State University, Ames IA 50011 USA; Asrar, Ghassem R. [Pacific Northwest National Laboratory, Joint Global Change Research Institute, College Park MD 20740 USA; Mao, Jiafu [Climate Change Science Institute, Oak Ridge National Laboratory, Oak Ridge TN 37831 USA; Li, Xiaoma [Department of Geological and Atmospheric Sciences, Iowa State University, Ames IA 50011 USA; Li, Wenyu [Ministry of Education Key Laboratory for Earth System Modeling, Center for Earth System Science, Tsinghua University, Beijing 100084 China

2016-12-18

The influence of urbanization on vegetation phenology is gaining considerable attention due to its implications for human health, cycling of carbon and other nutrients in Earth system. In this study, we examined the relationship between change in vegetation phenology and urban size, an indicator of urbanization, for the conterminous United States. We studied more than 4500 urban clusters of varying size to determine the impact of urbanization on plant phenology, with the aids of remotely sensed observations since 2003–2012. We found that phenology cycle (changes in vegetation greenness) in rural areas starts earlier (start of season, SOS) and ends later (end of season, EOS), resulting in a longer growing season length (GSL), when compared to the respective surrounding urban areas. The average difference of GSL between urban and rural areas over all vegetation types, considered in this study, is about 9 days. Also, the extended GSL in urban area is consistent among different climate zones in the United States, whereas their magnitudes are varying across regions. We found that a tenfold increase in urban size could result in an earlier SOS of about 1.3 days and a later EOS of around 2.4 days. As a result, the GSL could be extended by approximately 3.6 days with a range of 1.6–6.5 days for 25th ~ 75th quantiles, with a median value of about 2.1 days. For different vegetation types, the phenology response to urbanization, as defined by GSL, ranges from 1 to 4 days. The quantitative relationship between phenology and urbanization is of great use for developing improved models of vegetation phenology dynamics under future urbanization, and for developing change indicators to assess the impacts of urbanization on vegetation phenology.

Radionuclide and heavy metal concentrations in soil, vegetation, and fish collected around and within Tsicoma Lake in Santa Clara Canyon

International Nuclear Information System (INIS)

Fresquez, P.R.; Armstrong, D.R.; Naranjo, L. Jr.

1996-03-01

Radionuclide ( 3 H, 90 Sr, 137 Cs, 238 Pu, 239 Pu, total U) and heavy metal (Ag, As, Ba, Be, Cd, Cr, Hg, Ni, Pb, Sb, Se, Tl) contents were determined in soil, vegetation (overstory and understory), and fish (rainbow trout) collected around and within Tsicoma Lake in Santa Clara Canyon in 1995. All heavy metal and most radionuclide contents around or within the lake, except for U in soil, vegetation, and fish, were within or just above upper limit background. Detectable levels (where the analytical result was greater than two times counting uncertainty) of U in soils, vegetation, and fish were found in slightly higher concentrations than in background samples. Overall, however, maximum total committed effective dose equivalent (CEDE)(95% confidence level)--based on consumption of 46 lb of fish--from Tsicoma Lake (0.066 mrem/y) was within the maximum total CEDE from the ingestion of fish from the Mescalero National Fish Hatchery (background)(0.113 mrem/y)

Disaggregating tree and grass phenology in tropical savannas

Science.gov (United States)

Zhou, Qiang

Savannas are mixed tree-grass systems and as one of the world's largest biomes represent an important component of the Earth system affecting water and energy balances, carbon sequestration and biodiversity as well as supporting large human populations. Savanna vegetation structure and its distribution, however, may change because of major anthropogenic disturbances from climate change, wildfire, agriculture, and livestock production. The overstory and understory may have different water use strategies, different nutrient requirements and have different responses to fire and climate variation. The accurate measurement of the spatial distribution and structure of the overstory and understory are essential for understanding the savanna ecosystem. This project developed a workflow for separating the dynamics of the overstory and understory fractional cover in savannas at the continental scale (Australia, South America, and Africa). Previous studies have successfully separated the phenology of Australian savanna vegetation into persistent and seasonal greenness using time series decomposition, and into fractions of photosynthetic vegetation (PV), non-photosynthetic vegetation (NPV) and bare soil (BS) using linear unmixing. This study combined these methods to separate the understory and overstory signal in both the green and senescent phenological stages using remotely sensed imagery from the MODIS (MODerate resolution Imaging Spectroradiometer) sensor. The methods and parameters were adjusted based on the vegetation variation. The workflow was first tested at the Australian site. Here the PV estimates for overstory and understory showed best performance, however NPV estimates exhibited spatial variation in validation relationships. At the South American site (Cerrado), an additional method based on frequency unmixing was developed to separate green vegetation components with similar phenology. When the decomposition and frequency methods were compared, the frequency

Simulated Vegetation Response to Climate Change in California: The Importance of Seasonal Production Patterns

Science.gov (United States)

Kim, J. B.; Pitts, B.

2013-12-01

MC1 dynamic global vegetation model simulates vegetation response to climate change by simulating vegetation production, soil biogeochemistry, plant biogeography and fire. It has been applied at a wide range of spatial scales, yet the spatio-temporal patterns of simulated vegetation production, which drives the model's response to climate change, has not been examined in detail. We ran MC1 for California at a relatively fine scale, 30 arc-seconds, for the historical period (1895-2006) and for the future (2007-2100), using downscaled data from four CMIP3-based climate projections: A2 and B1 GHG emissions scenarios simulated by PCM and GFDL GCMs. The use of these four climate projections aligns our work with a body of climate change research work commissioned by the California Public Interest Energy Research (PIER) Program. The four climate projections vary not only in terms of changes in their annual means, but in the seasonality of projected climate change. We calibrated MC1 using MODIS NPP data for 2000-2011 as a guide, and adapting a published technique for adjusting simulated vegetation production by increasing the simulated plant rooting depths. We evaluated the simulation results by comparing the model output for the historical period with several benchmark datasets, summarizing by EPA Level 3 Ecoregions. Multi-year summary statistics of model predictions compare moderately well with Kuchler's potential natural vegetation map, National Biomass and Carbon Dataset, Leenhouts' compilation of fire return intervals, and, of course, the MODIS NPP data for 2000-2011. When we compared MC1's monthly NPP values with MODIS monthly GPP data (2000-2011), however, the seasonal patterns compared very poorly, with NPP/GPP ratio for spring (Mar-Apr-May) often exceeding 1, and the NPP/GPP ratio for summer (Jun-Jul-Aug) often flattening to zero. This suggests MC1's vegetation production algorithms are overly biased for spring production at the cost of summer production. We

Land-Use History and Contemporary Management Inform an Ecological Reference Model for Longleaf Pine Woodland Understory Plant Communities.

Energy Technology Data Exchange (ETDEWEB)

Brudvig, Lars A. [Department of Plant Biology, Michigan State University; Orrock, John L. [Department of Zoology, University of Wisconsin; Damschen, Ellen I. [Department of Zoology, University of Wisconsin; et al, et al

2014-01-23

Ecological restoration is frequently guided by reference conditions describing a successfully restored ecosystem; however, the causes and magnitude of ecosystem degradation vary, making simple knowledge of reference conditions insufficient for prioritizing and guiding restoration. Ecological reference models provide further guidance by quantifying reference conditions, as well as conditions at degraded states that deviate from reference conditions. Many reference models remain qualitative, however, limiting their utility. We quantified and evaluated a reference model for southeastern U.S. longleaf pine woodland understory plant communities. We used regression trees to classify 232 longleaf pine woodland sites at three locations along the Atlantic coastal plain based on relationships between understory plant community composition, soils lol(which broadly structure these communities), and factors associated with understory degradation, including fire frequency, agricultural history, and tree basal area. To understand the spatial generality of this model, we classified all sites together. and for each of three study locations separately. Both the regional and location-specific models produced quantifiable degradation gradients–i.e., progressive deviation from conditions at 38 reference sites, based on understory species composition, diversity and total cover, litter depth, and other attributes. Regionally, fire suppression was the most important degrading factor, followed by agricultural history, but at individual locations, agricultural history or tree basal area was most important. At one location, the influence of a degrading factor depended on soil attributes. We suggest that our regional model can help prioritize longleaf pine woodland restoration across our study region; however, due to substantial landscape-to-landscape variation, local management decisions should take into account additional factors (e.g., soil attributes). Our study demonstrates the utility

Land-Use History and Contemporary Management Inform an Ecological Reference Model for Longleaf Pine Woodland Understory Plant Communities

Science.gov (United States)

Brudvig, Lars A.; Orrock, John L.; Damschen, Ellen I.; Collins, Cathy D.; Hahn, Philip G.; Mattingly, W. Brett; Veldman, Joseph W.; Walker, Joan L.

2014-01-01

Ecological restoration is frequently guided by reference conditions describing a successfully restored ecosystem; however, the causes and magnitude of ecosystem degradation vary, making simple knowledge of reference conditions insufficient for prioritizing and guiding restoration. Ecological reference models provide further guidance by quantifying reference conditions, as well as conditions at degraded states that deviate from reference conditions. Many reference models remain qualitative, however, limiting their utility. We quantified and evaluated a reference model for southeastern U.S. longleaf pine woodland understory plant communities. We used regression trees to classify 232 longleaf pine woodland sites at three locations along the Atlantic coastal plain based on relationships between understory plant community composition, soils (which broadly structure these communities), and factors associated with understory degradation, including fire frequency, agricultural history, and tree basal area. To understand the spatial generality of this model, we classified all sites together and for each of three study locations separately. Both the regional and location-specific models produced quantifiable degradation gradients–i.e., progressive deviation from conditions at 38 reference sites, based on understory species composition, diversity and total cover, litter depth, and other attributes. Regionally, fire suppression was the most important degrading factor, followed by agricultural history, but at individual locations, agricultural history or tree basal area was most important. At one location, the influence of a degrading factor depended on soil attributes. We suggest that our regional model can help prioritize longleaf pine woodland restoration across our study region; however, due to substantial landscape-to-landscape variation, local management decisions should take into account additional factors (e.g., soil attributes). Our study demonstrates the utility of

Land-use history and contemporary management inform an ecological reference model for longleaf pine woodland understory plant communities.

Directory of Open Access Journals (Sweden)

Lars A Brudvig

Full Text Available Ecological restoration is frequently guided by reference conditions describing a successfully restored ecosystem; however, the causes and magnitude of ecosystem degradation vary, making simple knowledge of reference conditions insufficient for prioritizing and guiding restoration. Ecological reference models provide further guidance by quantifying reference conditions, as well as conditions at degraded states that deviate from reference conditions. Many reference models remain qualitative, however, limiting their utility. We quantified and evaluated a reference model for southeastern U.S. longleaf pine woodland understory plant communities. We used regression trees to classify 232 longleaf pine woodland sites at three locations along the Atlantic coastal plain based on relationships between understory plant community composition, soils (which broadly structure these communities, and factors associated with understory degradation, including fire frequency, agricultural history, and tree basal area. To understand the spatial generality of this model, we classified all sites together and for each of three study locations separately. Both the regional and location-specific models produced quantifiable degradation gradients-i.e., progressive deviation from conditions at 38 reference sites, based on understory species composition, diversity and total cover, litter depth, and other attributes. Regionally, fire suppression was the most important degrading factor, followed by agricultural history, but at individual locations, agricultural history or tree basal area was most important. At one location, the influence of a degrading factor depended on soil attributes. We suggest that our regional model can help prioritize longleaf pine woodland restoration across our study region; however, due to substantial landscape-to-landscape variation, local management decisions should take into account additional factors (e.g., soil attributes. Our study demonstrates

Spatial Autocorrelation Patterns of Understory Plant Species in a Subtropical Rainforest at Lanjenchi, Southern Taiwan

Directory of Open Access Journals (Sweden)

Su-Wei Fan

2010-06-01

Full Text Available Many studies described relationships between plant species and intrinsic or exogenous factors, but few quantified spatial scales of species patterns. In this study, quantitative methods were used to explore the spatial scale of understory species (including resident and transient species, in order to identify the influential factors of species distribution. Resident species (including herbaceous species, climbers and tree ferns < 1 m high were investigated on seven transects, each 5-meter wide and 300-meter long, at Lanjenchi plot in Nanjenshan Reserve, southern Taiwan. Transient species (seedling of canopy, subcanopy and shrub species < 1 cm diameter at breast height were censused in three of the seven transects. The herb coverage and seedling abundance were calculated for each 5 × 5 m quadrat along the transects, and Moran’s I and Galiano’s new local variance (NLV indices were then used to identify the spatial scale of autocorrelation for each species. Patterns of species abundance of understory layer varied among species at fine scale within 50 meters. Resident species showed a higher proportion of significant autocorrelation than the transient species. Species with large size or prolonged fronds or stems tended to show larger scales in autocorrelation. However, dispersal syndromes and fruit types did not relate to any species’ spatial patterns. Several species showed a significant autocorrelation at a 180-meter class which happened to correspond to the local replicates of topographical features in hilltops. The spatial patterns of understory species at Lanjenchi plot are mainly influenced by species’ intrinsic traits and topographical characteristics.

Vegetation Responses to Climate Variability in the Northern Arid to Sub-Humid Zones of Sub-Saharan Africa

Directory of Open Access Journals (Sweden)

Khaldoun Rishmawi

2016-11-01

Full Text Available In water limited environments precipitation is often considered the key factor influencing vegetation growth and rates of development. However; other climate variables including temperature; humidity; the frequency and intensity of precipitation events are also known to affect productivity; either directly by changing photosynthesis and transpiration rates or indirectly by influencing water availability and plant physiology. The aim here is to quantify the spatiotemporal patterns of vegetation responses to precipitation and to additional; relevant; meteorological variables. First; an empirical; statistical analysis of the relationship between precipitation and the additional meteorological variables and a proxy of vegetation productivity (the Normalized Difference Vegetation Index; NDVI is reported and; second; a process-oriented modeling approach to explore the hydrologic and biophysical mechanisms to which the significant empirical relationships might be attributed. The analysis was conducted in Sub-Saharan Africa; between 5 and 18°N; for a 25-year period 1982–2006; and used a new quasi-daily Advanced Very High Resolution Radiometer (AVHRR dataset. The results suggest that vegetation; particularly in the wetter areas; does not always respond directly and proportionately to precipitation variation; either because of the non-linearity of soil moisture recharge in response to increases in precipitation; or because variations in temperature and humidity attenuate the vegetation responses to changes in water availability. We also find that productivity; independent of changes in total precipitation; is responsive to intra-annual precipitation variation. A significant consequence is that the degree of correlation of all the meteorological variables with productivity varies geographically; so no one formulation is adequate for the entire region. Put together; these results demonstrate that vegetation responses to meteorological variation are more

Response of Competing Vegetation to Site Preparation on West Gulf Coastal Plain Commercial Forest Land

Science.gov (United States)

Gale L. Wolters; Henry A. Pearson; Ronald E. Thill; V. Clark Baldwin; Alton Martin

1995-01-01

The response of woody and herbaceous vegetation to site preparation, subsoil texture, and fertilization was measured on the West Gulf Coastal Plain. The influences of these treatments on competing vegetation were short-term. Drastic soil disturbance and fertilization briefly increased herbage production. Shear-windrow and shear-disk were generally the most effective...

Canopy arthropod responses to thinning and burning treatments in old-growth mixed-conifer forest in the Sierra Nevada, California

Science.gov (United States)

Thomas Rambo; Timothy Schowalter; Malcolm North

2014-01-01

We compared canopy arthropod responses to common fuels reduction treatments at Teakettle Experimental Forest in the south-central Sierra Nevada of California. We sampled arthropod communities among four dominant overstory conifer species and three dominant understory angiosperm species before and after overstory or understory thinning or no thinning treatments followed...

Spatiotemporal Dynamics in Vegetation GPP over the Great Khingan Mountains Using GLASS Products from 1982 to 2015

Directory of Open Access Journals (Sweden)

Ling Hu

2018-03-01

Full Text Available Gross primary productivity (GPP is an important parameter that represents the productivity of vegetation and responses to various ecological environments. The Greater Khingan Mountain (GKM is one of the most important state-owned forest bases, and boreal forests, including the largest primeval cold-temperature bright coniferous forest in China, are widely distributed in the GKM. This study aimed to reveal spatiotemporal vegetation variations in the GKM on the basis of GPP products that were generated by the Global LAnd Surface Satellite (GLASS program from 1982 to 2015. First, we explored the spatiotemporal distribution of vegetation across the GKM. Then we analyzed the relationships between GPP variation and driving factors, including meteorological elements, growing season length (GSL, and Fraction of Photosynthetically Active Radiation (FPAR, to investigate the dominant factor for GPP dynamics. Results demonstrated that (1 the spatial distribution of accumulated GPP (AG in spring, summer, autumn, and the growing season varied due to three main reasons: understory vegetation, altitude, and land cover; (2 interannual AG in summer, autumn, and the growing season significantly increased at the regional scale during the past 34 years under climate warming and drying; (3 interannual changes of accumulated GPP in the growing season (AGG at the pixel scale displayed a rapid expansion in areas with a significant increasing trend (p < 0.05 during the period of 1982–2015 and this trend was caused by the natural forest protection project launched in 1998; and finally, (4 an analysis of driving factors showed that daily sunshine duration in summer was the most important factor for GPP in the GKM and this is different from previous studies, which reported that the GSL plays a crucial role in other areas.

Soil Drought and Vegetation Response during 2001–2015 in North China Based on GLDAS and MODIS Data

Directory of Open Access Journals (Sweden)

Siyao Yang

2018-01-01

Full Text Available Drought is a natural disaster caused by long-term water deficit. Because the growth of crops and vegetation is closely related to soil moisture environment, it is of great significance to study the soil drought and vegetation response. In this paper, the soil moisture availability index (SMAI was developed for quantifying soil drought conditions. The effectiveness and the ability of SMAI to recognize drought events were analyzed, while the vegetation condition index (VCI was used to characterize the vegetation status. Temporal and spatial variations of soil drought and vegetation condition as well as the impacts of drought on vegetation in North China during 2001–2015 were comprehensively examined. We firstly concluded that SMAI related well with standardized precipitation evapotranspiration index (SPEI, and drought events can be detected by SMAI. Next, the mean value of SMAI in North China showed a decreasing trend in recent 15 years. Finally, the SMAI positively correlated with VCI in most areas of North China, and the response of four types of vegetation to SMAI differed over time. The results of SMAI on vegetation would assist drought research and application in North China.

Notable shifting in the responses of vegetation activity to climate change in China

Science.gov (United States)

Chen, Aifang; He, Bin; Wang, Honglin; Huang, Ling; Zhu, Yunhua; Lv, Aifeng

The weakening relationship between inter-annual temperature variability and vegetation activity in the Northern Hemisphere over the last three decades has been reported by a recent study. However, how and to what extent vegetation activity responds to climate change in China is still unclear. We applied the Pearson correlation and partial correlation methods with a moving 15-y window to the GIMMS NDVI dataset from NOAA/AVHRR and observed climate data to examine the variation in the relationships between vegetation activity and climate variables. Results showed that there was an expanding negative response of vegetation growth to climate warming and a positive role of precipitation. The change patterns between NDVI and climate variables over vegetation types during the past three decades pointed an expending negative correlation between NDVI and temperature and a positive role of precipitation over most of the vegetation types (meadow, grassland, shrub, desert, cropland, and forest). Specifically, correlation between NDVI and temperature (PNDVI-T) have shifted from positive to negative in most of the station of temperature-limited areas with evergreen broadleaf forests, whereas precipitation-limited temperate grassland and desert were characterized by a positive PNDVI-P. This study contributes to ongoing investigations of the effects of climate change on vegetation activity. It is also of great importance for designing forest management strategies to cope with climate change.

A Modeling Approach for Evaluating the Coupled Riparian Vegetation-Geomorphic Response to Altered Flow Regimes

Science.gov (United States)

Manners, R.; Wilcox, A. C.; Merritt, D. M.

2016-12-01

The ecogeomorphic response of riparian ecosystems to a change in hydrologic properties is difficult to predict because of the interactions and feedbacks among plants, water, and sediment. Most riparian models of community dynamics assume a static channel, yet geomorphic processes strongly control the establishment and survival of riparian vegetation. Using a combination of approaches that includes empirical relationships and hydrodynamic models, we model the coupled vegetation-topographic response of three cross-sections on the Yampa and Green Rivers in Dinosaur National Monument, to a shift in the flow regime. The locations represent the variable geomorphology and vegetation composition of these canyon-bound rivers. We account for the inundation and hydraulic properties of vegetation plots surveyed over three years within International River Interface Cooperative (iRIC) Fastmech, equipped with a vegetation module that accounts for flexible stems and plant reconfiguration. The presence of functional groupings of plants, or those plants that respond similarly to environmental factors such as water availability and disturbance are determined from flow response curves developed for the Yampa River. Using field measurements of vegetation morphology, distance from the channel centerline, and dominant particle size and modeled inundation properties we develop an empirical relationship between these variables and topographic change. We evaluate vegetation and channel form changes over decadal timescales, allowing for the integration of processes over time. From our analyses, we identify thresholds in the flow regime that alter the distribution of plants and reduce geomorphic complexity, predominately through side-channel and backwater infilling. Simplification of some processes (e.g., empirically-derived sedimentation) and detailed treatment of others (e.g., plant-flow interactions) allows us to model the coupled dynamics of riparian ecosystems and evaluate the impact of

The influence of parent material on vegetation response 15 years after the Dude Fire, Arizona

Science.gov (United States)

Jackson M. Leonard; Alvin L. Medina; Daniel G. Neary; Aregai Tecle

2015-01-01

This study examined the effects of two types of parent material, sandstone and limestone, on the response of vegetation growth after the 1990 Dude Fire in central Arizona. The operating hypothesis of the study was that, given the right conditions, severe wildfire can trigger vegetation type conversion. Overall, three patterns emerged: (1) oak density increased by 413%...

Importance of Coarse Woody Debris to Avian Communities in Loblolly Pine Forests

Energy Technology Data Exchange (ETDEWEB)

Lohr, S.M.; Gauthreaux, S.A.; Kilgo, J.C.

2001-06-14

Investigates the importance of standing and down coarse woody debris to bird communities in loblolly pine forests, researchers compared breeding and nonbreeding responses of birds among two coarse woody debris removal and control treatments. Quantification of vegetation layers to determine their effects on the experimental outcome coarse woody debris removal had no effect on the nonbreeding bird community. Most breeding and nonbreeding species used habitats with sparse midstory and well-developed understory, where as sparse canopy cover and dense midstory were important to some nonbreeding species. Snag and down coarse woody debris practices that maintain a dense understory, sparse midstory and canopy will create favorable breeding habitat.

Effects of understory prescribed burning on shortleaf pine (Pinus echinata Mill.)/mixed-hardwood forests

Science.gov (United States)

Katherine J. Elliott; James M. Vose

2005-01-01

We examined the effects of a single dormant season fire on overstory and understory species diversity and composition and tree seedling regeneration patterns the first and second years following a prescribed burn in the Conasauga River Watershed of southeastern Tennessee and northern Georgia. We asked: Can a single dormant season fire initiate a trajectory of overstory...

Improving dynamic global vegetation model (DGVM) simulation of western U.S. rangelands vegetation seasonal phenology and productivity

Science.gov (United States)

Kerns, B. K.; Kim, J. B.; Day, M. A.; Pitts, B.; Drapek, R. J.

2017-12-01

Ecosystem process models are increasingly being used in regional assessments to explore potential changes in future vegetation and NPP due to climate change. We use the dynamic global vegetation model MAPSS-Century 2 (MC2) as one line of evidence for regional climate change vulnerability assessments for the US Forest Service, focusing our fine tuning model calibration from observational sources related to forest vegetation. However, there is much interest in understanding projected changes for arid rangelands in the western US such as grasslands, shrublands, and woodlands. Rangelands provide many ecosystem service benefits and local rural human community sustainability, habitat for threatened and endangered species, and are threatened by annual grass invasion. Past work suggested MC2 performance related to arid rangeland plant functional types (PFT's) was poor, and the model has difficulty distinguishing annual versus perennial grasslands. Our objectives are to increase the model performance for rangeland simulations and explore the potential for splitting the grass plant functional type into annual and perennial. We used the tri-state Blue Mountain Ecoregion as our study area and maps of potential vegetation from interpolated ground data, the National Land Cover Data Database, and ancillary NPP data derived from the MODIS satellite. MC2 historical simulations for the area overestimated woodland occurrence and underestimated shrubland and grassland PFT's. The spatial location of the rangeland PFT's also often did not align well with observational data. While some disagreement may be due to differences in the respective classification rules, the errors are largely linked to MC2's tree and grass biogeography and physiology algorithms. Presently, only grass and forest productivity measures and carbon stocks are used to distinguish PFT's. MC2 grass and tree productivity simulation is problematic, in particular grass seasonal phenology in relation to seasonal patterns

Baseline concentrations of radionuclides and heavy metals in soils and vegetation around the DARHT facility: Construction phase (1997). Progress report

International Nuclear Information System (INIS)

Fresquez, P.R.; Haagenstad, H.T.; Naranjo, L. Jr.

1998-06-01

As part of the Department of Energy's Mitigation Action Plan for the Dual Axis Radiographic Hydrodynamic Test (DARHT) facility at Los Alamos National Laboratory (LANL), baseline concentrations of radionuclides ( 3 H, 137 Cs, 90 Sr, 238 Pu, 239,240 Pu, 241 Am, and tot U) and heavy metals (Ag, As, Ba, Be, Cd, Cr, Cu, Hg, Ni, Pb, Sb, Se, and Tl) in soil, sediment, and vegetation (overstory and understory) around the DARHT facility during the construction phase in 1997 were determined. Most radionuclides and heavy metals in soils, sediments, and vegetation, with the exception of 90 Sr in soils and sediments, were within upper (95%) limit background concentrations. Although the levels of 90 Sr in soils and sediments around the DARHT facility were higher than background, they were below LANL screening action levels ( -1 dry) and are of no concern

Radionuclide Concentration in Soils and Vegetation at Low-Level Radioactive Waste Disposal Area G during 2005

International Nuclear Information System (INIS)

Fresquez, P.R.; McNaughton, M.W.; Winch, M.J.

2005-01-01

Soil samples were collected at 15 locations and unwashed overstory and understory vegetation samples were collected from up to nine locations within and around the perimeter of Area G, the primary disposal facility for low-level radioactive solid waste at Los Alamos National Laboratory (LANL). Soil and plant samples were also collected from the proposed expansion area west of Area G for the purpose of gaining preoperational baseline data. Soil and plant samples were analyzed for radionuclides that have shown a history of detection in past years; these included 3 H, 238 Pu, 239,240 Pu, 241 Am, 234 U, 235 U, and 238 U for soils and 3 H, 238 Pu, and 239,240 Pu for plants. As in previous years, the highest levels of 3 H in soils and vegetation were detected at the south portion of Area G near the 3 H shafts; whereas, the highest concentrations of the Pu isotopes were detected in the northern and northeastern portions near the pads for transuranic waste. All concentrations of radionuclides in soils and vegetation, however, were still very low (pCi range) and far below LANL screening levels and regulatory standards

Coyote removal, understory cover, and survival of white-tailed deer neonates: Coyote Control and Fawn Survival

Energy Technology Data Exchange (ETDEWEB)

Kilgo, John C. [USDA Forest Service; Southern Research Station, New Ellenton, SC (United States); Vukovich, Mark [USDA Forest Service; Southern Research Station, New Ellenton, SC (United States); Ray, H. Scott [USDA Forest Service, Savannah River; New Ellenton, SC (United States); Shaw, Christopher E. [USDA Forest Service; Southern Research Station, New Ellenton, SC (United States); Ruth, Charles [South Carolina Dept. of Natural Resources, Columbia, SC (United States)

2014-09-01

Predation by coyotes (Canis latrans) on white-tailed deer (Odocoileus virginianus) neonates has led to reduced recruitment in many deer populations in southeastern North America. This low recruitment combined with liberal antlerless deer harvest has resulted in declines in some deer populations, and consequently, increased interest in coyote population control. We investigated whether neonate survival increased after coyote removal, whether coyote predation on neonates was additive to other mortality sources, and whether understory vegetation density affected neonate survival. We monitored neonate survival for 4 years prior to (2006–2009) and 3 years during (2010–2012) intensive coyote removal on 3 32-km² units on the United States Department of Energy’s Savannah River Site, South Carolina. We removed 474 coyotes (1.63 coyotes/km² per unit per year), reducing coyote abundance by 78% from pre-removal levels. The best model (w_i = 0.927) describing survival probability among 216 radio-collared neonates included a within-year quadratic time trend variable, date of birth, removal treatment, and a varying removal year effect. Under this model, survival differed between pre-treatment and removal periods and it differed among years during the removal period, being >100% greater than pre-treatment survival (0.228) during the first removal year (0.513), similar to pre-treatment survival during the second removal year (0.202), and intermediate during the third removal year (0.431). Despite an initial increase, the overall effect of coyote removal on neonate survival was modest. Mortality rate attributable to coyote predation was lowest during the first removal year (0.357) when survival was greatest, but the mortality rate from all other causes did not differ between the pretreatment period and any year during removals, indicating that coyote predation acted as an additive source of mortality. Survival probability was not related to

Generation of dose-response relationships to assess the effects of acidity in precipitation on growth and productivity of vegetation

International Nuclear Information System (INIS)

Evans, L.S.

1981-01-01

Experiments were performed with several plant species in natural environments as well in a greenhouse and/or tissue culture facilities to establish dose-response functions of plant responses to simulated acidic rain in order to determine environmental risk assessments to ambient levels of acidic rain. Response functions of foliar injury, biomass of leaves and seed of soybean and pinto beans, root yields of radishes and garden beets, and reproduction of bracken fern are considered. The dose-response function of soybean seed yields with the hydrogen ion concentration of simulated acidic rainfalls was expressed by the equation y = 21.06-1.01 log x where y = seed yield in grams per plant and x = the hydrogen concentration if μeq l -1 . The correlation coefficient of this relationship was -0.90. A similar dose-response function was generated for percent fertilization of ferns in a forest understory. When percent fertilization is plotted on logarithmic scale with hydrogen ion concentration of the simulated rain solution, the Y intercept is 51.18, slope -0.041 with a correlation coefficient of -0.98. Other dose-response functions were generated that assist in a general knowledge as to which plant species and which physiological processes are most impacted by acidic precipitation. Some responses did not produce convenient dose-response relationships. In such cases the responses may be altered by other environmental factors or there may be no differences among treatment means

A preliminary study of effects of feral pig density on native Hawaiian montane rainforest vegetation

Science.gov (United States)

Scheffler, Pamela Y.; Pratt, Linda; Foote, David; Magnacca, Karl

2012-01-01

This study aimed to examine the effects of different levels of pig density on native Hawaiian forest vegetation. Pig sign was measured across four pig management units in the 'Öla'a Forest from 1998 through 2004 and pig density estimated based upon pig activity. Six paired vegetation monitoring plots were established in the units, each pair straddling a pig fence. Percent cover and species richness of understory vegetation, ground cover, alien species, and preferred pig forage plants were measured in 1997 and 2003 and compared with pig density estimates. Rainfall and hunting effort and success by management personnel were also tracked over the study period. Vegetation monitoring found a higher percentage of native plants in pig-free or low-pig areas compared to those with medium or high pig densities, with no significant change in the percent native plant species between the first and second monitoring periods. Differences between plots were strongly affected by location, with a higher percentage of native plants in western plots, where pig damage has historically been lower. Expansion of this survey with more plots would help improve the statistical power to detect differences in vegetation caused by pigs. Because of the limited vegetation sampling in this study, the results must be viewed as descriptive. We compare the vegetation within 30 x 30 m plots across three thresholds of historical pig density and show how pig densities can change in unanticipated directions within management units. While these results cannot be extrapolated to area-wide effects of pig activity, these data do contribute to a growing body of information on the impacts of feral pigs on Hawaiian plant communities.

Vegetation response to extreme climate events on the Mongolian Plateau from 2000 to 2010

International Nuclear Information System (INIS)

John, Ranjeet; Chen Jiquan; Ouyang Zutao; Becker, Richard; Xiao Jingfeng; Samanta, Arindam; Ganguly, Sangram; Yuan Wenping; Batkhishig, Ochirbat

2013-01-01

Climate change has led to more frequent extreme winters (aka, dzud) and summer droughts on the Mongolian Plateau during the last decade. Among these events, the 2000–2002 combined summer drought–dzud and 2010 dzud were the most severe on vegetation. We examined the vegetation response to these extremes through the past decade across the Mongolian Plateau as compared to decadal means. We first assessed the severity and extent of drought using the Tropical Rainfall Measuring Mission (TRMM) precipitation data and the Palmer drought severity index (PDSI). We then examined the effects of drought by mapping anomalies in vegetation indices (EVI, EVI2) and land surface temperature derived from MODIS and AVHRR for the period of 2000–2010. We found that the standardized anomalies of vegetation indices exhibited positively skewed frequency distributions in dry years, which were more common for the desert biome than for grasslands. For the desert biome, the dry years (2000–2001, 2005 and 2009) were characterized by negative anomalies with peak values between −1.5 and −0.5 and were statistically different (P 2 = 65 and 60, p 2 = 53, p < 0.05). Our results showed significant differences in the responses to extreme climatic events (summer drought and dzud) between the desert and grassland biomes on the Plateau. (letter)

Post-fire burn severity and vegetation response following eight large wildfires across the Western United States

Science.gov (United States)

Leigh B. Lentile; Penelope Morgan; Andrew T. Hudak; Michael J. Bobbitt; Sarah A. Lewis; Alistair M. S. Smith; Peter R. Robichaud

2007-01-01

Vegetation response and burn severity were examined following eight large wildfires that burned in 2003 and 2004: two wildfires in California chaparral, two each in dry and moist mixed-conifer forests in Montana, and two in boreal forests in interior Alaska. Our research objectives were: 1) to characterize one year post-fire vegetation recovery relative to initial fire...

Dynamics of Understory Shrub Biomass in Six Young Plantations of Southern Subtropical China

Directory of Open Access Journals (Sweden)

Yuanqi Chen

2017-11-01

Full Text Available Understory shrubs are an important component of forest ecosystems and drive ecosystem processes, such as ecosystem carbon cycling. However, shrub biomass carbon stocks have rarely been reported, which limits our understanding of ecosystem C stock and cycling. In this study, we evaluated carbon accumulation of shrub species using allometric equations based on height and basal diameter in six subtropical plantations at the age of 1, 3, 4 and 6 years. The results showed that plantation type did not significantly affect the total biomass of shrubs, but it significantly affected the biomass of Rhodomyrtus tomentosa, Ilex asprella, Clerodendrum fortunatum and Baeckea frutescens. The biomass of dominant shrub species R. tomentosa, I. asprella, Gardenia jasminoides and Melastoma candidum increased with stand age, while the biomass of C. fortunatum and B. frutescens decreased. The inconsistent biomass-time patterns of different shrub species may be the primary reason for the altered total shrub biomass in each plantation. Consequently, we proposed that R. tomentosa, I. asprella, G. jasminoides and M. candidum could be preferable for understory carbon accumulation and should be maintained or planted because of their important functions in carbon accumulation and high economic values in the young plantations of southern subtropical China.

Vegetative reproduction capacities of floodplain willows--cutting response to competition and biomass loss.

Science.gov (United States)

Radtke, A; Mosner, E; Leyer, I

2012-03-01

While several studies on regeneration in Salicaceae have focused on seedling recruitment, little is known about factors controlling their vegetative reproduction. In two greenhouse experiments, we studied the response of floodplain willows (Salix fragilis, S. viminalis, S. triandra) to competition with Poa trivialis, and to shoot and root removal when planted as vegetative cuttings. In the first experiment, growth performance variables were analysed in relation to full competition, shoot competition, root competition and control, taking into account two different water levels. After 9 weeks, shoots were removed and the resprouting capacity of the bare cuttings was recorded. In the second experiment, the cutting performance of the three floodplain and an additional two fen willow species (S. cinerea, S. aurita) was compared when grown in three different soil compositions and with two different water levels. After 9 weeks, shoot and root biomass was removed and the bare cuttings were replanted to test their ability to resprout. Cutting performance and secondary resprouting were negatively affected by full and shoot competition while root competition had no or weak effects. The floodplain species performed better than the fen species in all soil types and water levels. Secondary resprouting capacity was also higher in the floodplain species, which showed an additional strong positive response to the previous waterlogging treatment. The results contribute to understanding of the vegetative regeneration ecology of floodplain willows, and suggest that the use of vegetative plantings in restoration plantings could be an effective strategy for recovering floodplain forests. © 2011 German Botanical Society and The Royal Botanical Society of the Netherlands.

Climate and vegetation in a semi-arid savanna: Development of a climate–vegetation response model linking plant metabolic performance to climate and the effects on forage availability for large herbivores

Directory of Open Access Journals (Sweden)

Armin H. Seydack

2012-02-01

Developing the climate–vegetation response model involved three main components, namely (1 defining indicators of forage availability to herbivores (nitrogen productivity, nitrogen quality, carbon-nutrient quality, (2 identifying herbivore species guilds of similar nutritional requirements with respect to these indicators [bulk feeders with tolerance to fibrous herbage (buffalo, waterbuck, bulk feeders with preference for high nitrogen quality forage (short grass preference grazers: blue wildebeest and zebra and selective feeders where dietary items of relatively high carbon-nutrient quality represented key forage resources (selective grazers: sable antelope, roan antelope, tsessebe, eland] and (3 developing a process model where the expected effects of plant metabolic responses to climate on key forage resources were made explicit. According to the climate–vegetation response model both shorter-term transient temperature acclimation pulses and longer-term shifts in plant metabolic functionality settings were predicted to have occurred in response to temperature trends over the past century. These temperature acclimation responses were expected to have resulted in transient pulses of increased forage availability (increased nitrogen- and carbon-nutrient quality, as well as the progressive long-term decline of the carbon-nutrient quality of forage. Conservation implications: The climate–vegetation response model represents a research framework for further studies contributing towards the enhanced understanding of landscape-scale functioning of savanna systems with reference to the interplay between climate, vegetation and herbivore population dynamics. Gains in such understanding can support sound conservation management.

Susceptibility to Phytophthora ramorum and inoculum production potential of some common eastern forest understory plant species

Science.gov (United States)

Paul W. Tooley; Marsha Browning

2009-01-01

Twenty-five plant species (21 genera, 14 families), which comprise a portion of the understory in forests of the Eastern United States, were evaluated for susceptibility to infection by Phytophthora ramorum. The degree to which P. ramorum is able to form sporangia and chlamydospores was also assessed on...

Using a Dynamic Global Vegetation Model to Simulate the Response of Vegetation to Warming at the Paleocene-Eocene Boundary

Science.gov (United States)

Shellito, C. J.; Sloan, L. C.

2004-12-01

A major turnover in benthic marine and terrestrial fauna marks the Initial Eocene Thermal Maximum (IETM) (~55Ma), a period of ~150 ky in which there was a rapid rise in deep sea and high latitude sea surface temperatures by 5-8C. Curiously, no major responses to this warming in the terrestrial floral record have been detected to date. Here, we present results from experiments examining the response of the global distribution of vegetation to changes in climate at the IETM using the NCAR Land Surface Model (LSM1.2) integrated with a dynamic global vegetation model (DGVM). DGVMs allow vegetation to respond to and interact with climate, and thus, provide a unique new method for addressing questions regarding feedbacks between the ecosystem and climate in Earth's past. However, there are a number of drawbacks to using these models that can affect interpretation of results. More specifically, these drawbacks involve uncertainties in the application of modern plant functional types to paleo-flora simulations, inaccuracies in the model climatology used to drive the DGVM, and lack of available detail regarding paleo-geography and paleo-soil type for use in model boundary conditions. For a better understanding of these drawbacks, we present results from a series of tests in the NCAR LSM-DGVM which examine (1) the effect of removing C4 grasses from the available plant functional types in the model; (2) model sensitivity to a change in soil texture; and (3), model sensitivity to a change in the value of pCO2 used in the photosynthetic rate equations. We consider our DGVM results for the IETM in light of output from these sensitivity experiments.

Response of Vegetation on Gravel Bars to Management Measures and Floods: Case Study From the Czech Republic

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Eremiášová Renata

2014-08-01

Full Text Available This article investigates response of vegetation on gravel bars to management measures and floods. The management measures consisted of the partial removal of gravel and vegetation cover, and were applied to six gravel bars on the Ostravice River, Czech Republic. Unexpected floods occu-rred in 2010, with the amplitude of 5- to 50-year repetition. Research of vegetation on the gravel bars consisted of vegetation survey before the management works; the monitoring of vegetation development over the following year and the verification of the relationships of species diversity, successional stages and the biotope conditions with the help of multivariate analysis (detrended correspondence analysis. Vegetation on the gravel bars was at different successional stages, and had higher diversity and vegetation cover before the management measures and floods. The mul-tivariate analysis revealed a shift toward initial successional stages with high demand on moisture, temperature and light after both management measures and floods.

Grassland and forest understory biomass emissions from prescribed fires in the southeastern United States – RxCADRE 2012

Science.gov (United States)

Smoke measurements were made during grass and forest understory prescribed fires as part of a comprehensive program to understand fire and smoke behaviour. Instruments deployed on the ground, airplane and tethered aerostat platforms characterized the smoke plumes through measure...

Ecosystem properties self-organize in response to a directional fog-vegetation interaction.

Science.gov (United States)

Stanton, Daniel E; Armesto, Juan J; Hedin, Lars O

2014-05-01

Feedbacks between vegetation and resource inputs can lead to the local, self-organization of ecosystem properties. In particular, feedbacks in response to directional resources (e.g., coastal fog, slope runoff) can create complex spatial patterns, such as vegetation banding. Although similar feedbacks are thought to be involved in the development of ecosystems, clear empirical examples are rare. We created a simple model of a fog-influenced, temperate rainforest in central Chile, which allows the comparison of natural banding patterns to simulations of various putative mechanisms. We show that only feedbacks between plants and fog were able to replicate the characteristic distributions of vegetation, soil water, and soil nutrients observed in field transects. Other processes, such as rainfall, were unable to match these diagnostic distributions. Furthermore, fog interception by windward trees leads to increased downwind mortality, leading to progressive extinction of the leeward edge. This pattern of ecosystem development and decay through self-organized processes illustrates, on a relatively small spatial and temporal scale, the patterns predicted for ecosystem evolution.

Response of vegetable organisms to quasi-monochromatic light of different duration, intensity and wavelength

Energy Technology Data Exchange (ETDEWEB)

Budagovsky, A V; Solovykh, N V [I.V.Michurin All-Russian Recearch Institute of Fruit Crops Genetics and Breeding (Russian Federation); Budagovskaya, O N [I.V.Michurin All-Russia Research and Development Institute of Gardening, Michurinsk, Tambov region (Russian Federation); Budagovsky, I A [P N Lebedev Physics Institute, Russian Academy of Sciences, Moscow (Russian Federation)

2015-04-30

By the example of vegetable organisms differing in structure and functional properties it is shown that their response to the action of quasi-monochromatic light from laser sources does not obey the Bunsen – Roscoe dose law. The dependence of biological effect on the irradiation time has the multimodal (multiextremal) form with alternating maxima and minima of the stimulating effect. Such a property manifests itself in the spectral ranges, corresponding to photoinduced conversion of chromoproteins of photocontrol systems and is probably related to the cyclic variations of metabolic activity in vegetable cells. (biophotonics)

Radionuclide Concentration in Soils and Vegetation at Low-Level Radioactive Waste Disposal Area G during 2005

Energy Technology Data Exchange (ETDEWEB)

P.R. Fresquez; M.W. McNaughton; M.J. Winch

2005-10-01

Soil samples were collected at 15 locations and unwashed overstory and understory vegetation samples were collected from up to nine locations within and around the perimeter of Area G, the primary disposal facility for low-level radioactive solid waste at Los Alamos National Laboratory (LANL). Soil and plant samples were also collected from the proposed expansion area west of Area G for the purpose of gaining preoperational baseline data. Soil and plant samples were analyzed for radionuclides that have shown a history of detection in past years; these included {sup 3}H, {sup 238}Pu, {sup 239,240}Pu, {sup 241}Am, {sup 234}U, {sup 235}U, and {sup 238}U for soils and {sup 3}H, {sup 238}Pu, and {sup 239,240}Pu for plants. As in previous years, the highest levels of {sup 3}H in soils and vegetation were detected at the south portion of Area G near the {sup 3}H shafts; whereas, the highest concentrations of the Pu isotopes were detected in the northern and northeastern portions near the pads for transuranic waste. All concentrations of radionuclides in soils and vegetation, however, were still very low (pCi range) and far below LANL screening levels and regulatory standards.

Phenological synchrony and seasonality of understory Rubiaceae in the Atlantic Forest, Bahia, Brazil

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Heitor Scarpati Liuth

2013-03-01

Full Text Available In tropical forests with low seasonality, climatic variables generally exert a weak influence on the phenology of species. The seasonality of phenophases in closely related taxa can be controlled by phylogenetic constraints in such environments. In this study, our aim was to describe the phenology of Rubiaceae in the understory of the Atlantic Forest in the southern part of Bahia, Brazil, as well as to evaluate the seasonality and phenological synchrony of this family. For two years, we observed 90 individuals belonging to 13 species, in an area of 0.2 ha. Leaf flushing and leaf fall did not demonstrate any seasonality, were continuous for most species and correlated with few of the climatic variables. Flowering was seasonal and correlated positively with all climatic variables. Species exhibited seasonality for this phenophase with high flowering overlap among species of Psychotria, indicating an aggregated pattern for this genus. Fruiting was also seasonal and correlated with all the climatic variables, unripe fruit development peaking at the beginning of the season during which humidity is highest and fruit ripening peaking in the season during which humidity is slightly lower. The vegetative and flowering patterns observed in the study area are commonly seen in other tropical forests. The reproductive seasonality of this family can facilitate the attraction of biotic agents, as postulated in the facilitation hypothesis. Our results demonstrate that climatic variables influenced the phenological patterns observed here, although the high reproductive seasonality and interspecific synchrony, especially in congeneric species, raises the possibility that phylogenetic proximity plays a role in the pattern of the family Rubiaceae.

Targeted reforestation could reverse declines in connectivity for understory birds in a tropical habitat corridor.

Science.gov (United States)

Fagan, Matthew E; DeFries, Ruth S; Sesnie, Steven E; Arroyo-Mora, J Pablo; Chazdon, Robin L

2016-07-01

Re-establishing connectivity between protected areas isolated by habitat clearing is a key conservation goal in the humid tropics. In northeastern Costa Rica, payments for environmental services (PES) and a government ban on deforestation have subsidized forest protection and reforestation in the San Juan-La Selva Biological Corridor (SJLSBC), resulting in a decline in mature forest loss and the expansion of tree plantations. We use field studies and graph models to assess how conservation efforts have altered functional connectivity over the last 25 years for four species of insectivorous understory birds. Field playback studies assessed how reforestation habitat quality affected the willingness of Myrmeciza exsul, Henicorhina leucosticta, Thamnophilus atrinucha, and Glyphorynchus spirurus to travel outside forest habitat for territorial defense. Observed travel distances were greatest in nonnative and native tree plantations with high understory stem density, regardless of overstory composition. In contrast, tree plantations with low stem density had travel responses comparable to open pasture for three of the four bird species. We modeled landscape connectivity for each species using graph models based on varying possible travel distances in tree plantations, gallery forests, and pastures. From 1986 to 2011, connectivity for all species declined in the SJLSBC landscape (5825 km 2 ) by 14% to 21% despite only a 4.9% net loss in forest area and the rapid expansion of tree plantations over 2% of the landscape. Plantation placement in the landscape limited their potential facilitation of connectivity because they were located either far from forest cover or within already contiguous forest areas. We mapped current connectivity bottlenecks and identified priority areas for future reforestation. We estimate that reforestation of priority areas could improve connectivity by 2% with only a 1% gain in forest cover, an impressive gain given the small area reforested

Forty years of vegetation change on the Missouri River floodplain

Science.gov (United States)

Johnson, W. Carter; Dixon, Mark D.; Scott, Michael L.; Rabbe, Lisa; Larson, Gary; Volke, Malia; Werner, Brett

2012-01-01

Comparative inventories in 1969 and 1970 and in 2008 of vegetation from 30 forest stands downstream of Garrison Dam on the Missouri River in central North Dakota showed (a) a sharp decline in Cottonwood regeneration; (b) a strong compositional shift toward dominance by green ash; and (c) large increases in invasive understory species, such as smooth brome, reed canary grass, and Canada thistle. These changes, and others discovered during remeasurement, have been caused by a complex of factors, some related to damming (altered hydrologic and sediment regimes, delta formation, and associated wet-dry cycles) and some not (diseases and expansion of invasive plants). Dominance of green ash, however, may be short lived, given the likelihood that the emerald ash borer will arrive in the Dakotas in 5-10 years, with potentially devastating effects. The prospects for recovery of this valuable ecosystem, rich in ecosystem goods and services and in American history, are daunting.

Spectral contribution of understory to forest reflectance in a boreal site: an analysis of EO-1 Hyperion data

Czech Academy of Sciences Publication Activity Database

Rautianien, M.; Lukeš, Petr

2015-01-01

Roč. 171, dec (2015), s. 98-104 ISSN 0034-4257 R&D Projects: GA MŠk(CZ) LO1415 Institutional support: RVO:67179843 Keywords : forest reflectance model * hyperspectral * boreal * leaf area index * understory Subject RIV: EH - Ecology, Behaviour Impact factor: 5.881, year: 2015

A non-destructive method for quantifying small-diameter woody biomass in southern pine forests

Science.gov (United States)

D. Andrew Scott; Rick Stagg; Morris Smith

2006-01-01

Quantifying the impact of silvicultural treatments on woody understory vegetation largely has been accomplished by destructive sampling or through estimates of frequency and coverage. In studies where repeated measures of understory biomass across large areas are needed, destructive sampling and percent cover estimates are not satisfactory. For example, estimates of...

Developing the Guidelines for Reclamation to Forest Vegetation in the Athabasca Oil Sands Region

Energy Technology Data Exchange (ETDEWEB)

Straker, J. [Integral Ecology Group Ltd., Victoria, BC (Canada); Cumulative Environmental Management Association, Fort McMurray, AB (Canada). Reclamation Working Group, Terrestrial Subgroup; Donald, G. [Donald Functional and Applied Ecology Inc., Victoria, BC (Canada); Cumulative Environmental Management Association, Fort McMurray, AB (Canada). Reclamation Working Group, Terrestrial Subgroup

2010-07-01

This paper discussed the development process behind and the structure of the Guidelines for Reclamation to Forest Vegetation in the Athabasca Oil Sands Region. The advances present in the second edition, published in 2010, were described relative to the first edition, which was published in 1998. Oils sands mining companies are mandated to use the manual under the Alberta Environmental Protection and Enhancement Act. The paper provided an overview of the structure of the second edition and presented the process used to develop the second edition. It also described the planning approaches for revegetative treatments and the planning guidance of overstory and understory species selection. The methods for evaluating revegetative success were also described with particular reference to plant community composition and soil salinity indicators as examples of indicator development. The goal of the manual is to provide guidance on re-establishing the vegetation component of upland ecosystems on reclaimed landscapes and on evaluating the success of the re-establishment, assuming that the reclaimed plant communities should have species characteristic of native plant communities in the region, that the trends of vegetation community and structure development on reclaimed land should be similar to native plant communities in the region, and that the reclaimed ecosystems should have development trajectories that satisfy land-use objectives and provide resilience against natural disturbances. 15 refs., 1 tab., 1 fig.

Critical impact of vegetation physiology on the continental hydrologic cycle in response to increasing CO2

Science.gov (United States)

Lemordant, Léo; Gentine, Pierre; Swann, Abigail S.; Cook, Benjamin I.; Scheff, Jacob

2018-04-01

Predicting how increasing atmospheric CO2 will affect the hydrologic cycle is of utmost importance for a range of applications ranging from ecological services to human life and activities. A typical perspective is that hydrologic change is driven by precipitation and radiation changes due to climate change, and that the land surface will adjust. Using Earth system models with decoupled surface (vegetation physiology) and atmospheric (radiative) CO2 responses, we here show that the CO2 physiological response has a dominant role in evapotranspiration and evaporative fraction changes and has a major effect on long-term runoff compared with radiative or precipitation changes due to increased atmospheric CO2. This major effect is true for most hydrological stress variables over the largest fraction of the globe, except for soil moisture, which exhibits a more nonlinear response. This highlights the key role of vegetation in controlling future terrestrial hydrologic response and emphasizes that the carbon and water cycles are intimately coupled over land.

Baseline concentrations of radionuclides and heavy metals in soils and vegetation around the DARHT facility: Construction phase (1997). Progress report

Energy Technology Data Exchange (ETDEWEB)

Fresquez, P.R.; Haagenstad, H.T.; Naranjo, L. Jr.

1998-06-01

As part of the Department of Energy`s Mitigation Action Plan for the Dual Axis Radiographic Hydrodynamic Test (DARHT) facility at Los Alamos National Laboratory (LANL), baseline concentrations of radionuclides ({sup 3}H, {sup 137}Cs, {sup 90}Sr, {sup 238}Pu, {sup 239,240}Pu, {sup 241}Am, and {sup tot}U) and heavy metals (Ag, As, Ba, Be, Cd, Cr, Cu, Hg, Ni, Pb, Sb, Se, and Tl) in soil, sediment, and vegetation (overstory and understory) around the DARHT facility during the construction phase in 1997 were determined. Most radionuclides and heavy metals in soils, sediments, and vegetation, with the exception of {sup 90}Sr in soils and sediments, were within upper (95%) limit background concentrations. Although the levels of {sup 90}Sr in soils and sediments around the DARHT facility were higher than background, they were below LANL screening action levels (<4.4 pCi g{sup {minus}1} dry) and are of no concern.

Understory fuel variation at the Carolina Sandhills National Wildlife Refuge: a description of chemical and physical properties

Science.gov (United States)

Evelyn S. Wenk; G. Geoff Wang; Joan L. Walker

2013-01-01

Upland forest in the Carolina Sandhills National Wildlife Refuge is characterized by a longleaf pine (Pinus palustris) canopy with a variable understory and ground-layer species composition. The system was historically maintained by fire and has been managed with prescribed fire in recent decades. A management goal is to reduce turkey oak (...

Estimating individual tree mid- and understory rank-size distributions from airborne laser scanning in semi-arid forests

Science.gov (United States)

Tyson L. Swetnam; Donald A. Falk; Ann M. Lynch; Stephen R. Yool

2014-01-01

Limitations inherent to airborne laser scanning (ALS) technology and the complex sorting and packing relationships of forests complicate accurate remote sensing of mid- and understory trees, especially in denser forest stands. Self-similarities in rank-sized individual tree distributions (ITD), e.g. bole diameter or height, are a well-understood property of natural,...

Family richness and biomass of understory invertebrates in early and late successional habitats of northern New Hampshire

Science.gov (United States)

Matthew K. Wilson; Winsor H. Lowe; Keith Nislow

2014-01-01

In the northeastern United States, many vertebrate species rely on early successional forest habitats (ESHs). ESHs may also support higher invertebrate diversity and abundance than late successional habitats (LSHs). We assessed the differences in family-level richness and biomass of understory terrestrial invertebrates during the summer season in paired ESH (3-7 years...

Effects of ecosystem-based management treatments

Science.gov (United States)

Michael G. Harrington; Carl E. Fiedler; Stephen F. Arno; Ward W. McCaughey; Leon J. Theroux; Clinton E. Carlson; Kristin L. Zouhar; Thomas H. DeLuca; Donald J. Bedunah; Dayna M. Ayers; Elizabeth A. Beringer; Sallie J. Hejl; Lynn Bacon; Robert E. Benson; Jane Kapler Smith; Rick Floch

1999-01-01

The prescribed burn treatments were applied to reduce pre-existing and new slash fuel loadings, reduce understory tree density to lower crown fire potential, stimulate vigor of decadent understory vegetation, produce mineral seedbeds for seral species establishment, and increase availability of mineral nutrients. To test the feasibility of prescribed burning under a...

The responses of net primary production (NPP) and total carbon storage for the continental United States to changes in atmospheric CO{sub 2}, climate, and vegetation

Energy Technology Data Exchange (ETDEWEB)

McGuire, D.A. [Marine Biological Lab., Woods Hole, MA (United States)

1995-06-01

We extrapolated 3 biogeochemistry models (BIOME-BGC, CENTURY, and TEM) across the continental US with the vegetation distributions of 3 biogeography models (BIOME2, DOLY, and MAPSS) for contemporary climate at 355 ppmv CO{sub 2} and each of 3 GCM climate scenarios at 710 ppmv. For contemporary conditions, continental NPP ranges from 3132 to 3854 TgC/yr and total carbon storage ranges from 109 to 125 PgC. The responses of NPP range from no response (BIOME-BGC with DOLY or MAPSS vegetations for UKMO climate) to increases of 53% and 56% (TEM with BIOME2 vegetations for GFDL and OSU climates). The responses of total carbon storage vary from a decrease of 39% (BIOME-BGC with MAPSS vegetation for UKMO climate) to increases of 52% and 56% (TEM with BIOME2 vegetations for OSU and GFDL climates). The UKMO responses of BIOME-BGC with MAPSS vegetation are caused by both decreased forest area (from 44% to 38%) and photosynthetic water stress. The OSU and GFDL responses of TEM with BIOME2 vegetations are caused by forest expansion (from 46% to 67% for OSU and to 75% for GFDL) and increased nitrogen cycling.

Feasibility of coupled empirical and dynamic modeling to assess climate change and air pollution impacts on temperate forest vegetation of the eastern United States.

Science.gov (United States)

McDonnell, T C; Reinds, G J; Sullivan, T J; Clark, C M; Bonten, L T C; Mol-Dijkstra, J P; Wamelink, G W W; Dovciak, M

2018-03-01

Changes in climate and atmospheric nitrogen (N) deposition caused pronounced changes in soil conditions and habitat suitability for many plant species over the latter half of the previous century. Such changes are expected to continue in the future with anticipated further changing air temperature and precipitation that will likely influence the effects of N deposition. To investigate the potential long-term impacts of atmospheric N deposition on hardwood forest ecosystems in the eastern United States in the context of climate change, application of the coupled biogeochemical and vegetation community model VSD+PROPS was explored at three sites in New Hampshire, Virginia, and Tennessee. This represents the first application of VSD+PROPS to forest ecosystems in the United States. Climate change and elevated (above mid-19th century) N deposition were simulated to be important factors for determining habitat suitability. Although simulation results suggested that the suitability of these forests to support the continued presence of their characteristic understory plant species might decline by the year 2100, low data availability for building vegetation response models with PROPS resulted in uncertain results at the extremes of simulated N deposition. Future PROPS model development in the United States should focus on inclusion of additional foundational data or alternate candidate predictor variables to reduce these uncertainties. Copyright © 2017 Elsevier Ltd. All rights reserved.

Salt marsh recovery from a crude oil spill: Vegetation, oil weathering, and response

International Nuclear Information System (INIS)

Hoff, R.Z.; Shigenaka, G.; Henry, C.B. Jr.

1993-01-01

When a spill of Prudhoe Bay crude oil covered a fringing Salicornia virginica marsh in Fidalgo Bay, Washington (northern Puget Sound) in February 1991, response personnel used several low-impact techniques to remove oil from the marsh, and minimized access by cleanup workers. Following the response, a monitoring program was established to track marsh recovery, and to document the effectiveness of the response techniques used and their impacts on the marsh. Through monthly sampling over a 16-month period, vegetative growth was monitored and chemical degradation of remaining oil was tracked. Sampling was conducted along transects located in four areas affected in different ways by the spill, including an oiled, trampled section; an oiled, vacuumed section; and an oiled, washed, and vacuumed section. In addition, a control transect was established in an unoiled adjacent marsh. The study included both biological and chemical components. Biological measurements included percent cover of live vegetation (sampled monthly) and below-ground plant biomass (sampled at the beginning of each growing season in April 1991 and April 1992). Sediment samples included surface sediment (monthly) and core samples collected at the beginning and end of the growing seasons. Sediment samples were analyzed using gas chromatography/mass spectroscopy, and indicator compounds were tracked to determine rates of oil degradation. Results from 16 months of post-spill monitoring show that foot trampling was most detrimental to marsh plants, while washing with vacuuming removed the most oil and minimized adverse impacts to vegetation. Dense clay substrate helped prevent oil from penetrating the sediment, thus minimizing acute toxic effects from oil exposure to marsh plant rootstock. By the second growing season post-spill, Salicornia and other marsh plants were growing in all areas except one heavily oiled patch

Cortical responses to salient nociceptive and not nociceptive stimuli in vegetative and minimal conscious state

Science.gov (United States)

de Tommaso, Marina; Navarro, Jorge; Lanzillotti, Crocifissa; Ricci, Katia; Buonocunto, Francesca; Livrea, Paolo; Lancioni, Giulio E.

2015-01-01

Aims: Questions regarding perception of pain in non-communicating patients and the management of pain continue to raise controversy both at a clinical and ethical level. The aim of this study was to examine the cortical response to salient visual, acoustic, somatosensory electric non-nociceptive and nociceptive laser stimuli and their correlation with the clinical evaluation. Methods: Five Vegetative State (VS), 4 Minimally Conscious State (MCS) patients and 11 age- and sex-matched controls were examined. Evoked responses were obtained by 64 scalp electrodes, while delivering auditory, visual, non-noxious electrical and noxious laser stimulation, which were randomly presented every 10 s. Laser, somatosensory, auditory and visual evoked responses were identified as a negative-positive (N2-P2) vertex complex in the 500 ms post-stimulus time. We used Nociception Coma Scale-Revised (NCS-R) and Coma Recovery Scale (CRS-R) for clinical evaluation of pain perception and consciousness impairment. Results: The laser evoked potentials (LEPs) were recognizable in all cases. Only one MCS patient showed a reliable cortical response to all the employed stimulus modalities. One VS patient did not present cortical responses to any other stimulus modality. In the remaining participants, auditory, visual and electrical related potentials were inconstantly present. Significant N2 and P2 latency prolongation occurred in both VS and MCS patients. The presence of a reliable cortical response to auditory, visual and electric stimuli was able to correctly classify VS and MCS patients with 90% accuracy. Laser P2 and N2 amplitudes were not correlated with the CRS-R and NCS-R scores, while auditory and electric related potentials amplitude were associated with the motor response to pain and consciousness recovery. Discussion: pain arousal may be a primary function also in vegetative state patients while the relevance of other stimulus modalities may indicate the degree of cognitive and motor

Spesies Tumbuhan Penyusun Vegetasi Lantai di Wilayah Restorasi Taman Nasional Gunung Merapi di Ngablak, Magelang, Jawa Tengah

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Purnomo Purnomo

2017-04-01

Full Text Available Vegetation restoration by Mount Merapi National Park (TNGM in Ngablak, Magelang, Central Java need the floristic data composition of understory vegetation. The objectives of this research were to identify and to determine the importance values of each plants species that composed of that restoration area. Sample collections were conducted using survey method for their morphological characters as voucher specimens that were used for species identification. Vegetation analysis was conducted using the quadratic method; shrubs (5x5 m2, grasses and herbs (1x1 m2, and importance values were analysed using relative frequencies and densities. The result shows that understory vegetation on the restoration area in Ngablak was composed of 60 seed plant species from 18 plant families. There were 7 plant families that dominate the region; Papilionaceae (13 species, Asteraceae (11, Poaceae (Grasses (10, Cyperaceae (Sedges (5, Amaranthaceae (3, Mimosaceae (3 and Commelinaceae (3. Plants species that have important value more than 25% in this restoration area were Cymbopogon citratus (sereh, Mimosa pudica (Putri malu, Gomphrena serrata (Bunga kancing, Pannisetum purpureum (Rumput gajah, Ageratum conyzoides (Wedusan, dan Euphatorium inulifolium (kirinyuh. The external factors that influence the growth of the understory vegetation are pH of soil and soil moisture.

Addition of ash on drained forested peatlands in southern Sweden. Effects on forest production, fluxes of greenhouse gases, peat properties, understorey vegetation and groundwater chemistry; Tillfoersel av aska i skog paa dikad torvmark i soedra Sverige. Effekter paa skogsproduktion, floeden av vaexthusgaser, torvegenskaper, markvegetation och grundvattenkemi

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Sikstroem, Ulf; Bjoerk, Robert G; Ring, Eva; Ernfors, Maria; Jacobson, Staffan; Nilsson, Mats; Klemedtsson, Leif

2009-02-15

The objective of the present study was to evaluate effects of wood-ash addition on drained peatlands in southern Sweden. Tree growth, greenhouse gases, peat properties, microbial biomass and processes, understory vegetation and groundwater chemistry were measured in three field experiments (some variables were not measured in all experiments): (i) 168 Perstorp, an oligotrophic mire with Scotch pine (Pinus sylvestris L.), where 2.5 tonnes d.w. of wood ash/ha (2.5WA) was added in 1982; (ii) 273 Anderstorp, also an oligotrophic mire with Scots pine, where 3.3 tonnes d.w. crushed ash/ha (3.3KA) and 6.6 tonnes d.w. crushed/ha (6.6KA) was added in 2003; (iii) 278 Skogaryd, a minerotrophic mire with Norway spruce (Picea abies L. Karst.), where the same doses of crushed ash as in Anderstorp were added in 2006. Untreated controls were included in all experiments. At Anderstorp, increased tree growth was indicated, at least in the treatment with the highest ash dose during the first five years after treatment. The annual emissions of CO{sub 2}, CH4 and N{sub 2}O from the peat were unaffected. At Skogaryd, the growth was unaffected and the emissions of both CO{sub 2} and N{sub 2}O were reduced during the first two years after treatment. In general, the significant ash effects (2.5WA and 3.3KA evaluated) on peat characteristics, microbial biomass and processes were found in the upper soil (0-5 cm) at the recently treated sites (Anderstorp and Skogaryd), and at greater depths (5-30 cm) at Perstorp, where the ash was added 25 years ago. In the ash treatment at Perstorp, there was a shift in the plant community structure and a decrease in species diversity of the understory vegetation. However, at this point of time, the forest stand had become substantially denser than on the control plots. Hence, these effects on the understory vegetation may have been an indirect effect of the ash-induced altered tree stand properties. In Skogaryd, no shift in the plant community was found

Vegetation responses to sagebrush-reduction treatments measured by satellites

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Johnston, Aaron; Beever, Erik; Merkle, Jerod A.; Chong, Geneva W.

2018-01-01

Time series of vegetative indices derived from satellite imagery constitute tools to measure ecological effects of natural and management-induced disturbances to ecosystems. Over the past century, sagebrush-reduction treatments have been applied widely throughout western North America to increase herbaceous vegetation for livestock and wildlife. We used indices from satellite imagery to 1) quantify effects of prescribed-fire, herbicide, and mechanical treatments on vegetative cover, productivity, and phenology, and 2) describe how vegetation changed over time following these treatments. We hypothesized that treatments would increase herbaceous cover and accordingly shift phenologies towards those typical of grass-dominated systems. We expected prescribed burns would lead to the greatest and most-prolonged effects on vegetative cover and phenology, followed by herbicide and mechanical treatments. Treatments appeared to increase herbaceous cover and productivity, which coincided with signs of earlier senescence − signals expected of grass-dominated systems, relative to sagebrush-dominated systems. Spatial heterogeneity for most phenometrics was lower in treated areas relative to controls, which suggested treatment-induced homogenization of vegetative communities. Phenometrics that explain spring migrations of ungulates mostly were unaffected by sagebrush treatments. Fire had the strongest effect on vegetative cover, and yielded the least evidence for sagebrush recovery. Overall, treatment effects were small relative to those reported from field-based studies for reasons most likely related to sagebrush recovery, treatment specification, and untreated patches within mosaicked treatment applications. Treatment effects were also small relative to inter-annual variation in phenology and productivity that was explained by temperature, snowpack, and growing-season precipitation. Our results indicated that cumulative NDVI, late-season phenometrics, and spatial

Influence of tree species on the herbaceous understory and soil chemical characteristics in a silvopastoral system in semi-arid northeastern Brazil

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R. S. C. Menezes

1999-12-01

Full Text Available Studies from some semi-arid regions of the world have shown the beneficial effect of trees in silvopastoral systems, by promoting the formation of resource islands and increasing the sustainability of the system. No data are available in this respect for tree species of common occurrence in semi-arid Northeastern Brazil. In the present study, conducted in the summer of 1996, three tree species (Zyziphus joazeiro, Spondias tuberosa and Prosopis juliflora: found within Cenchrus ciliaris pastures were selected to evaluate differences on herbaceous understory and soil chemical characteristics between samples taken under the tree canopy and in open grass areas. Transects extending from the tree trunk to open grass areas were established, and soil (0-15 cm and herbaceous understory (standing live biomass in 1 m² plots samples were taken at 0, 25, 50, 100, 150 and 200% of the average canopy radius (average radius was 6.6 ± 0.5, 4.5 ± 0.5, and 5.3 ± 0.8 m for Z. joazeiro, P. juliflora, and S. tuberosa , respectively. Higher levels of soil C, N, P, Ca, Mg, K, and Na were found under the canopies of Z. joazeiro and P. juliflora: trees, as compared to open grass areas. Only soil Mg organic P were higher under the canopies of S. tuberosa trees, as compared to open grass areas. Herbaceous understory biomass was significantly lower under the canopy of S. tuberosa and P. juliflora trees (107 and 96 g m-2, respectively relatively to open grass areas (145 and 194 g m-2. No herbaceous biomass differences were found between Z. joazeiro canopies and open grass areas (107 and 87 g m-2, respectively. Among the three tree species studied, Z. joazeiro was the one that presented the greatest potential for use in a silvopastoral system at the study site, since it had a larger nutrient stock in the soil without negatively affecting herbaceous understory biomass, relatively to open grass areas.

Studying the Post-Fire Response of Vegetation in California Protected Areas with NDVI-based Pheno-Metrics

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Jia, S.; Gillespie, T. W.

2016-12-01

Post-fire response from vegetation is determined by the intensity and timing of fires as well as the nature of local biomes. Though the field-based studies focusing on selected study sites helped to understand the mechanisms of post-fire response, there is a need to extend the analysis to a broader spatial extent with the assistance of remotely sensed imagery of fires and vegetation. Pheno-metrics, a series of variables on the growing cycle extracted from basic satellite measurements of vegetation coverage, translate the basic remote sensing measurements such as NDVI to the language of phenology and fire ecology in a quantitative form. In this study, we analyzed the rate of biomass removal after ignition and the speed of post-fire recovery in California protected areas from 2000 to 2014 with USGS MTBS fire data and USGS eMODIS pheno-metrics. NDVI drop caused by fire showed the aboveground biomass of evergreen forest was removed much slower than shrubland because of higher moisture level and greater density of fuel. In addition, the above two major land cover types experienced a greatly weakened immediate post-fire growing season, featuring a later start and peak of season, a shorter length of season, and a lower start and peak of NDVI. Such weakening was highly correlated with burn severity, and also influenced by the season of fire and the land cover type, according to our modeling between the anomalies of pheno-metrics and the difference of normalized burn ratio (dNBR). The influence generally decayed over time, but can remain high within the first 5 years after fire, mostly because of the introduction of exotic species when the native species were missing. Local-specific variables are necessary to better address the variance within the same fire and improve the outcomes of models. This study can help ecologists in validating the theories of post-fire vegetation response mechanisms and assist local fire managers in post-fire vegetation recovery.

Restoring Native Forest Understory: The Influence of Ferns and Light in a Hawaiian Experiment

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Robert Shallenberger

2013-03-01

Full Text Available Ecological restoration is an increasingly important component of sustainable land management. We explore potential facilitative relationships for enhancing the cost-effectiveness of restoring native forest understory, focusing on two factors: (1 overstory shade and (2 possible facilitation by a fern (Dryopteris wallichiana, one of few native colonists of pasture in our montane Hawaiˈi study system. We planted 720 understory tree seedlings and over 4000 seeds of six species under six planting treatments: a full factorial combination of low, medium and high light, situating plantings in either the presence or absence of a mature fern. After three years, 75% of outplanted seedlings survived. Seedling survivorship was significantly higher in the presence of a fern (79% vs. 71% without a fern and in medium and low light conditions (81% vs. 64% in high light. Relative height was highest at low to medium light levels. After 2.2 years, 2.8% of the planted seeds germinated. We observed no significant differences in seed germination relative to light level or fern presence. Analyzing several approaches, we found nursery germination of seeds followed by outplanting ca. 20% less costly than direct seeding in the field. This study opens new questions about facilitation mechanisms that have the potential to increase the extent and effectiveness of restoration efforts.

Response of vegetable seed germination to solar radiation penetrating through soil

International Nuclear Information System (INIS)

Hamamoto, H.

1999-01-01

Response of vegetable seeds to irradiation and emergence of plants seeded at various depths were investigated to clarify the effects of solar radiation through soil on vegetable seed germination. Seeds of eight vegetable species were germinated in Petri dishes under 11-h irradiation per day. Seed germination was delayed in tomato (Licopersicon esculentum Mill.) but accelerated in perilla (Perilla ocymoides L.) and Japanese hornwort (Cryptotaenia japonica Hassk.) with increase in irradiation at the intensities higher than 0.4W m -2 . Seeds of Japanese radish (Raphanus sativus L.), watermelon (Citrullus lanatus Matsum.), and Chinese cabbage (Brassica campestris L.) showed delayed germination at more than 4-6W m -2 . No effect of irradiation on lettuce (Lactuca sativa L.) and carrot (Daucus carota L.) seed germination was seen. For tomato, Japanese radish and Japanese hornwort, the effects of irradiation time on germination were also investigated. Tomato seed germination was delayed and Japanese hornwort seed germination was accelerated with increase in irradiation time beyond 2h per day. The emergence of tomato and Japanese hornwort covered with Shimokuriyagawa loam soil (Kuriyagawa soil) and vermiculite at depths of less than 5mm, 5-10mm and 10-15mm was observed. Plants emerged more rapidly from 5-10mm depths than from less than 5mm depth in tomato. The plants seeded at 10-15mm depths emerged as rapidly as those at 5-10mm depths using vermiculite but later than those at other depths using Kuriyagawa soil, probably due to high bulk density. The early emergence of Japanese hornwort was fastest from less than 5mm depth. The plants seeded at 5-10mm depths did not emerge much slower than those at less than 5mm depth. A seeding depth of 5-10mm was suitable for the rapid emergence of those vegetables covered with both the soil and vermiculite. (author)

Developing and Testing a Robust, Multi-Scale Framework for the Recovery of Longleaf Pine Understory Communities

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2015-05-01

effects on seed germination of native and invasive Eastern deciduous forest understory plants. Forest Ecology and Management 261:1401–1408. Estes, J...Defense, Washington Headquarters Services, Directorate for Information Operations and Reports (0704-0188), 1215 Jefferson Davis Highway, Suite 1204...in longleaf pine savannas. Figure 3.3.2. Results of multivariate classification and regression tree analysis. Figure 3.3.3. Comparison of Classes

Vegetation productivity responses to drought on tribal lands in the four corners region of the Southwest USA

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El-Vilaly, Mohamed Abd Salam; Didan, Kamel; Marsh, Stuart E.; van Leeuwen, Willem J. D.; Crimmins, Michael A.; Munoz, Armando Barreto

2018-03-01

For more than a decade, the Four Corners Region has faced extensive and persistent drought conditions that have impacted vegetation communities and local water resources while exacerbating soil erosion. These persistent droughts threaten ecosystem services, agriculture, and livestock activities, and expose the hypersensitivity of this region to inter-annual climate variability and change. Much of the intermountainWestern United States has sparse climate and vegetation monitoring stations, making fine-scale drought assessments difficult. Remote sensing data offers the opportunity to assess the impacts of the recent droughts on vegetation productivity across these areas. Here, we propose a drought assessment approach that integrates climate and topographical data with remote sensing vegetation index time series. Multisensor Normalized Difference Vegetation Index (NDVI) time series data from 1989 to 2010 at 5.6 km were analyzed to characterize the vegetation productivity changes and responses to the ongoing drought. A multi-linear regression was applied to metrics of vegetation productivity derived from the NDVI time series to detect vegetation productivity, an ecosystem service proxy, and changes. The results show that around 60.13% of the study area is observing a general decline of greenness ( pchallenges to the region's already stressed ecosystems. Whereas the results provide additional insights into this isolated and vulnerable region, the drought assessment approach used in this study may be adapted for application in other regions where surface-based climate and vegetation monitoring record is spatially and temporally limited.

Vegetation Changes in the Permafrost Regions of the Qinghai-Tibetan Plateau from 1982-2012: Different Responses Related to Geographical Locations and Vegetation Types in High-Altitude Areas.

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Zhiwei Wang

Full Text Available The Qinghai-Tibetan Plateau (QTP contains the largest permafrost area in a high-altitude region in the world, and the unique hydrothermal environments of the active layers in this region have an important impact on vegetation growth. Geographical locations present different climatic conditions, and in combination with the permafrost environments, these conditions comprehensively affect the local vegetation activity. Therefore, the responses of vegetation to climate change in the permafrost region of the QTP may be varied differently by geographical location and vegetation condition. In this study, using the latest Global Inventory Modeling and Mapping Studies (GIMMS Normalized Difference Vegetation Index (NDVI product based on turning points (TPs, which were calculated using a piecewise linear model, 9 areas within the permafrost region of the QTP were selected to investigate the effect of geographical location and vegetation type on vegetation growth from 1982 to 2012. The following 4 vegetation types were observed in the 9 selected study areas: alpine swamp meadow, alpine meadow, alpine steppe and alpine desert. The research results show that, in these study areas, TPs mainly appeared in 2000 and 2001, and almost 55.1% and 35.0% of the TPs were located in 2000 and 2001. The global standardized precipitation evapotranspiration index (SPEI and 7 meteorological variables were selected to analyze their correlations with NDVI. We found that the main correlative variables to vegetation productivity in study areas from 1982 to 2012 were precipitation, surface downward long-wave radiation and temperature. Furthermore, NDVI changes exhibited by different vegetation types within the same study area followed similar trends. The results show that regional effects rather than vegetation type had a larger impact on changes in vegetation growth in the permafrost regions of the QTP, indicating that climatic factors had a larger impact in the permafrost

Responses of sri lankan traditional rice to photoperiod at early vegetative stage

International Nuclear Information System (INIS)

Rathnathunga, U.U.E.; Geekiyanage, S.

2017-01-01

Rice is a photoperiod sensitive plant for flowering initiation. Effect of photoperiod can be important in vegetative growth and yield determination in rice. The objective of the research was to determine the effect of photoperiod on the vegetative responses of Sri Lankan traditional rice germplasm (SLTRG). Forty five traditional rice accessions (TRA), 5 improved rice varieties (IR), Sri Lankan wild rice (Oryza nivara and Oryza rufipogan) and Oryza japonica accessions 6782 and 6752 were grown in short day (SD), day neutral (DN) and long day (LD) conditions. Days to reach the fifth leaf stage (DFL), plant height (PH) and tiller number (TN) at the fifth leaf stage were recorded. Twenty three genotypes including 21 TRA, Oryza japonica 6752 and Oryza nivara did not respond to photoperiod having non-significant values for DFL, PH and TN among photoperiods. The DFL was affected in 25 genotypes; among them both DFL and PH were affected in 7 genotypes. DFL was significantly increased during LD in 4 TRA while DFL was significantly reduced in all 5 IR and 5 TRA. DFL was significantly increased in Oryza japonica 6782 and 5 TRA under SD. In 4 TRA, DFL was reduced under SD. The TN was affected in Oryza japonica 6782 only under SD with increased DFL. The DFL was significantly increased under DN in Oryza rufipogan, 5 TRA and 2 IR. Both SD and LD photoperiods differently affected the interaction between DFL and PH in TRA while only LD affected that of IR. DN had an effect on the interaction between DFL and PH only in wild rice Oryza rufipogon. Variation of vegetative growth response to photoperiod may depict the wide genetic basis of SLTRG. (author)

Nile Basin Vegetation Response and Vulnerability to Climate Change: A Multi-Sensor Remote Sensing Approach

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Yitayew, M.; Didan, K.; Barreto-munoz, A.

2013-12-01

changes in the vegetation index signal and to a lesser degree the change in land cover and land use over the last 30 years. Using the climate data record we looked at the drivers of this change. The sensitivity of the basin to climate change was assessed using the multi-linear regression analysis on the covariance of the change in key phenology parameters and the two climate drivers considered here. The overall response was very complex owing to the complicated climate regime and topography of the region. Vegetation response was mostly stable in high lands with a slightly decreasing trend over low and mid-elevations. Over the same period we also observed an intensification of agriculture production corresponding to an increase in percent cover and productivity. We also observed a decrease in forest cover associated with land use conversion. These changes were mostly driven by the precipitation regimes with little impact of the temperature. Climate models project an eventual decrease in precipitation and increase in temperature over the basin. Coupled with these results and observations these projected changes point to major challenges to the vegetation cover, productivity, and associated ecosystem services of the Nile basin.

On the formation of dense understory layers in forests worldwide: consequences and implications for forest dynamics, biodiversity, and succession

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Alejandro A. Royo; Walter P. Carson

2006-01-01

The mechanistic basis underpinning forest succession is the gap-phase paradigm in which overstory disturbance interacts with seedling and sapling shade tolerance to determine successional trajectories. The theory, and ensuing simulation models, typically assume that understory plants have little impact on the advance regeneration layer's composition. We challenge...

Responses of Vegetation Growth to Climatic Factors in Shule River Basin in Northwest China: A Panel Analysis

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Jinghui Qi

2017-03-01

Full Text Available The vegetation response to climatic factors is a hot topic in global change research. However, research on vegetation in Shule River Basin, which is a typical arid region in northwest China, is still limited, especially at micro scale. On the basis of Moderate-resolution Imaging Spectroradiometer (MODIS Normalized Difference Vegetation Index (NDVI data and daily meteorological data, employing panel data models and other mathematical models, the aim of this paper is to reveal the interactive relationship between vegetation variation and climatic factors in Shule River Basin. Results show that there is a widespread greening trend in the whole basin during 2000–2015, and 80.28% of greening areas (areas with vegetation improvement are distributed over upstream region, but the maximum vegetation variation appears in downstream area. The effects of climate change on NDVI lag about half to one month. The parameters estimated using panel data models indicate that precipitation and accumulated temperature have positive contribution to NDVI. With every 1-mm increase in rainfall, NDVI increases by around 0.223‰ in upstream area and 0.6‰ in downstream area. With every 1-°C increase in accumulated temperature, NDVI increases by around 0.241‰ in upstream area and 0.174‰ in downstream area. Responses of NDVI to climatic factors are more sensitive when these factors are limiting than when they are not limiting. NDVI variation has performance in two seasonal and inter-annual directions, and the range of seasonal change is far more than that of inter-annual change. The inverted U-shaped curve of the variable intercepts reflects the seasonal change. Our results might provide some scientific basis for the comprehensive basin management.

Climatic drivers of vegetation based on wavelet analysis

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Claessen, Jeroen; Martens, Brecht; Verhoest, Niko E. C.; Molini, Annalisa; Miralles, Diego

2017-04-01

Vegetation dynamics are driven by climate, and at the same time they play a key role in forcing the different bio-geochemical cycles. As climate change leads to an increase in frequency and intensity of hydro-meteorological extremes, vegetation is expected to respond to these changes, and subsequently feed back on their occurrence. This response can be analysed using time series of different vegetation diagnostics observed from space, in the optical (e.g. Normalised Difference Vegetation Index (NDVI), Solar Induced Fluorescence (SIF)) and microwave (Vegetation Optical Depth (VOD)) domains. In this contribution, we compare the climatic drivers of different vegetation diagnostics, based on a monthly global data-cube of 24 years at a 0.25° resolution. To do so, we calculate the wavelet coherence between each vegetation-related observation and observations of air temperature, precipitation and incoming radiation. The use of wavelet coherence allows unveiling the scale-by-scale response and sensitivity of the diverse vegetation indices to their climatic drivers. Our preliminary results show that the wavelet-based statistics prove to be a suitable tool for extracting information from different vegetation indices. Going beyond traditional methods based on linear correlations, the application of wavelet coherence provides information about: (a) the specific periods at which the correspondence between climate and vegetation dynamics is larger, (b) the frequencies at which this correspondence occurs (e.g. monthly or seasonal scales), and (c) the time lag in the response of vegetation to their climate drivers, and vice versa. As expected, areas of high rainfall volumes are characterised by a strong control of radiation and temperature over vegetation. Furthermore, precipitation is the most important driver of vegetation variability over short terms in most regions of the world - which can be explained by the rapid response of leaf development towards available water content

Smart plants, smart models? On adaptive responses in vegetation-soil systems

Science.gov (United States)

van der Ploeg, Martine; Teuling, Ryan; van Dam, Nicole; de Rooij, Gerrit

2015-04-01

Hydrological models that will be able to cope with future precipitation and evapotranspiration regimes need a solid base describing the essence of the processes involved [1]. The essence of emerging patterns at large scales often originates from micro-behaviour in the soil-vegetation-atmosphere system. A complicating factor in capturing this behaviour is the constant interaction between vegetation and geology in which water plays a key role. The resilience of the coupled vegetation-soil system critically depends on its sensitivity to environmental changes. To assess root water uptake by plants in a changing soil environment, a direct indication of the amount of energy required by plants to take up water can be obtained by measuring the soil water potential in the vicinity of roots with polymer tensiometers [2]. In a lysimeter experiment with various levels of imposed water stress the polymer tensiometer data suggest maize roots regulate their root water uptake on the derivative of the soil water retention curve, rather than the amount of moisture alone. As a result of environmental changes vegetation may wither and die, or these changes may instead trigger gene adaptation. Constant exposure to environmental stresses, biotic or abiotic, influences plant physiology, gene adaptations, and flexibility in gene adaptation [3-7]. To investigate a possible relation between plant genotype, the plant stress hormone abscisic acid (ABA) and the soil water potential, a proof of principle experiment was set up with Solanum Dulcamare plants. The results showed a significant difference in ABA response between genotypes from a dry and a wet environment, and this response was also reflected in the root water uptake. Adaptive responses may have consequences for the way species are currently being treated in models (single plant to global scale). In particular, model parameters that control root water uptake and plant transpiration are generally assumed to be a property of the plant

Forest structure of oak plantations after silvicultural treatment to enhance habitat for wildlife

Science.gov (United States)

Twedt, Daniel J.; Phillip, Cherrie-Lee P.; Guilfoyle, Michael P.; Wilson, R. Randy; Schweitzer, Callie Jo; Clatterbuck, Wayne K.; Oswalt, Christopher M.

2016-01-01

During the past 30 years, thousands of hectares of oak-dominated bottomland hardwood plantations have been planted on agricultural fields in the Mississippi Alluvial Valley. Many of these plantations now have closed canopies and sparse understories. Silvicultural treatments could create a more heterogeneous forest structure, with canopy gaps and increased understory vegetation for wildlife. Lack of volume sufficient for commercial harvest in hardwood plantations has impeded treatments, but demand for woody biomass for energy production may provide a viable means to introduce disturbance beneficial for wildlife. We assessed forest structure in response to prescribed pre-commercial perturbations in hardwood plantations resulting from silvicultural treatments: 1) row thinning by felling every fourth planted row; 2) multiple patch cuts with canopy gaps of gaps appear likely to be filled by regenerating saplings.

Understory cover responses to pinon-juniper treatments across tree dominance gradients in the Great Basin

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Piñon (Pinus spp.) and juniper (Juniperus spp.) trees are reduced to restore native vegetation and avoid high severity fires where they have invaded sagebrush (Artemisia tridentata Nutt.) communities. To recommend treatment implementation which avoids threshold-crossing to invasive plant dominance w...

Complex responses of spring alpine vegetation phenology to snow cover dynamics over the Tibetan Plateau, China.

Science.gov (United States)

Wang, Siyuan; Wang, Xiaoyue; Chen, Guangsheng; Yang, Qichun; Wang, Bin; Ma, Yuanxu; Shen, Ming

2017-09-01

Snow cover dynamics are considered to play a key role on spring phenological shifts in the high-latitude, so investigating responses of spring phenology to snow cover dynamics is becoming an increasingly important way to identify and predict global ecosystem dynamics. In this study, we quantified the temporal trends and spatial variations of spring phenology and snow cover across the Tibetan Plateau by calibrating and analyzing time series of the NOAA AVHRR-derived normalized difference vegetation index (NDVI) during 1983-2012. We also examined how snow cover dynamics affect the spatio-temporal pattern of spring alpine vegetation phenology over the plateau. Our results indicated that 52.21% of the plateau experienced a significant advancing trend in the beginning of vegetation growing season (BGS) and 34.30% exhibited a delaying trend. Accordingly, the snow cover duration days (SCD) and snow cover melt date (SCM) showed similar patterns with a decreasing trend in the west and an increasing trend in the southeast, but the start date of snow cover (SCS) showed an opposite pattern. Meanwhile, the spatial patterns of the BGS, SCD, SCS and SCM varied in accordance with the gradients of temperature, precipitation and topography across the plateau. The response relationship of spring phenology to snow cover dynamics varied within different climate, terrain and alpine plant community zones, and the spatio-temporal response patterns were primarily controlled by the long-term local heat-water conditions and topographic conditions. Moreover, temperature and precipitation played a profound impact on diverse responses of spring phenology to snow cover dynamics. Copyright © 2017 Elsevier B.V. All rights reserved.

Trophic flexibility and the persistence of understory birds in intensively logged rainforest.

Science.gov (United States)

Edwards, David P; Woodcock, Paul; Newton, Rob J; Edwards, Felicity A; Andrews, David J R; Docherty, Teegan D S; Mitchell, Simon L; Ota, Takahiro; Benedick, Suzan; Bottrell, Simon H; Hamer, Keith C

2013-10-01

Effects of logging on species composition in tropical rainforests are well known but may fail to reveal key changes in species interactions. We used nitrogen stable-isotope analysis of 73 species of understory birds to quantify trophic responses to repeated intensive logging of rainforest in northern Borneo and to test 4 hypotheses: logging has significant effects on trophic positions and trophic-niche widths of species, and the persistence of species in degraded forest is related to their trophic positions and trophic-niche widths in primary forest. Species fed from higher up the food chain and had narrower trophic-niche widths in degraded forest. Species with narrow trophic-niche widths in primary forest were less likely to persist after logging, a result that indicates a higher vulnerability of dietary specialists to local extinction following habitat disturbance. Persistence of species in degraded forest was not related to a species' trophic position. These results indicate changes in trophic organization that were not apparent from changes in species composition and highlight the importance of focusing on trophic flexibility over the prevailing emphasis on membership of static feeding guilds. Our results thus support the notion that alterations to trophic organization and interactions within tropical forests may be a pervasive and functionally important hidden effect of forest degradation. © 2013 Society for Conservation Biology.

SO/sub 2/ dose-response sensitivity classification data for crops and natural vegetation species

Energy Technology Data Exchange (ETDEWEB)

Irving, P.M.; Ballou, S.W.

1980-09-01

Over the past several years studies have been made on the interaction of sulfur dioxide (SO/sub 2/) and vegetation by performing field research and by developing analytical procedures for applying field observation data to energy impact assessments. As a result of this work, numerous reports have been prepared on crop-pollutant interactions, such as dose-response data; on the applications of such data to screening approaches for identifying crops at risk; and on models that predict crop yield reductions from point source emissions of SO/sub 2/. Data that were used for these studies, such as the crop-at-risk screening procedure, are presented in this report. Maps are also presented that show the national distribution of SO/sub 2/-sensitive crops and natural vegetation.

Direct and indirect effects of a dense understory on tree seedling recruitment in temperate forests: habitat-mediated predation versus competition

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Alejandro A. Royo; Walter P. Carson

2008-01-01

In forests characterized by a dense woody and herbaceous understory layer, seedling recruitment is often directly suppressed via interspecific competition. Alternatively, these dense layers may indirectly lower tree recruitment by providing a haven for seed and seedling predators that prey on neighboring plant species. To simultaneously...

Spatio-temporal variation of vegetation coverage and its response to climate change in North China plain in the last 33 years

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A, Duo; Zhao, Wenji; Qu, Xinyuan; Jing, Ran; Xiong, Kai

2016-12-01

Global climate change has led to significant vegetation changes in the past half century. North China Plain, the most important grain production base of china, is undergoing a process of prominent warming and drying. The vegetation coverage, which is used to monitor vegetation change, can respond to climate change (temperature and precipitation). In this study, GIMMS (Global Inventory Modelling and Mapping Studies)-NDVI (Normalized Difference Vegetation Index) data, MODIS (Moderate-resolution Imaging Spectroradiometer) - NDVI data and climate data, during 1981-2013, were used to investigate the spatial distribution and changes of vegetation. The relationship between climate and vegetation on different spatial (agriculture, forest and grassland) and temporal (yearly, decadal and monthly) scales were also analyzed in North China Plain. (1) It was found that temperature exhibiting a slight increase trend (0.20 °C/10a, P 0.05). The climate mutation period was during 1991-1994. (2) Vegetation coverage slight increase was observed in the 55% of total study area, with a change rate of 0.00039/10a. Human activities may not only accelerate the changes of the vegetation coverage, but also c effect to the rate of these changes. (3) Overall, the correlation between the vegetation coverage and climatic factor is higher in monthly scale than yearly scale. The correlation analysis between vegetation coverage and climate changes showed that annual vegetation coverage was better correlatend with precipitation in grassland biome; but it showed a better correlated with temperature i the agriculture biome and forest biome. In addition, the vegetation coverage had sensitive time-effect respond to precipitation. (4) The vegetation coverage showed the same increasing trend before and after the climatic variations, but the rate of increase slowed down. From the vegetation coverage point of view, the grassland ecological zone had an obvious response to the climatic variations, but the

Leaf gas exchange of understory spruce-fir saplings in relict cloud forests, southern Appalachian Mountains, USA

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Reinhardt, K.; Smith, W.K. [Wake Forest Univ., Winston-Salem, NC (United States). Dept. of Biology

2008-01-15

Global climate change is expected to increase regional cloud ceiling levels in many mountainous forested areas of the world. This study investigated environmental influences on the gas exchange physiology of understory red spruce and Fraser fir trees at 2 sites in the Appalachian mountains. The study hypothesized that the humid, cloudy environment would influence the photosynthetic performance of the trees, and that the species would adapt to low, diffuse light. The study also predicted that leaf conductance to carbon dioxide (CO{sub 2}) would be high as a result of low leaf-to-air-vapour pressure deficit (LAVD). The study demonstrated that leaf conductance decreased exponentially as LAVD increased. Predawn leaf water potentials remained stable, while late afternoon values declined. It was concluded that leaf gas exchange was correlated with the response of leaf conductance and LAVD. The cloudy, humid environment strongly influenced tree leaf gas exchange and water relations. It was suggested that further research is needed to investigate cloud impacts on carbon gain and water relations. 72 refs., 1 tab., 8 figs.

Changes in habitat use at rainforest edges through succession: A case study of understory birds in the Brazilian Amazon

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Luke L. Powell; Gustavo Zurita; Jared D.  Wolfe; Erik I.  Johnson; Philip C  Stouffer

2015-01-01

Primary tropical rain forests are being rapidly perforated with new edges via roads, logging, and pastures, and vast areas of secondary forest accumulate following abandonment of agricultural lands. To determine how insectivorous Amazonian understory birds respond to edges between primary rain forest and three age classes of secondary forest, we radio-tracked two...

Detecting fragmentation extinction thresholds for forest understory plant species in peninsular Spain.

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Rueda, Marta; Moreno Saiz, Juan Carlos; Morales-Castilla, Ignacio; Albuquerque, Fabio S; Ferrero, Mila; Rodríguez, Miguel Á

2015-01-01

Ecological theory predicts that fragmentation aggravates the effects of habitat loss, yet empirical results show mixed evidences, which fail to support the theory instead reinforcing the primary importance of habitat loss. Fragmentation hypotheses have received much attention due to their potential implications for biodiversity conservation, however, animal studies have traditionally been their main focus. Here we assess variation in species sensitivity to forest amount and fragmentation and evaluate if fragmentation is related to extinction thresholds in forest understory herbs and ferns. Our expectation was that forest herbs would be more sensitive to fragmentation than ferns due to their lower dispersal capabilities. Using forest cover percentage and the proportion of this percentage occurring in the largest patch within UTM cells of 10-km resolution covering Peninsular Spain, we partitioned the effects of forest amount versus fragmentation and applied logistic regression to model occurrences of 16 species. For nine models showing robustness according to a set of quality criteria we subsequently defined two empirical fragmentation scenarios, minimum and maximum, and quantified species' sensitivity to forest contraction with no fragmentation, and to fragmentation under constant forest cover. We finally assessed how the extinction threshold of each species (the habitat amount below which it cannot persist) varies under no and maximum fragmentation. Consistent with their preference for forest habitats probability occurrences of all species decreased as forest cover contracted. On average, herbs did not show significant sensitivity to fragmentation whereas ferns were favored. In line with theory, fragmentation yielded higher extinction thresholds for two species. For the remaining species, fragmentation had either positive or non-significant effects. We interpret these differences as reflecting species-specific traits and conclude that although forest amount is of

Detecting fragmentation extinction thresholds for forest understory plant species in peninsular Spain.

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Marta Rueda

Full Text Available Ecological theory predicts that fragmentation aggravates the effects of habitat loss, yet empirical results show mixed evidences, which fail to support the theory instead reinforcing the primary importance of habitat loss. Fragmentation hypotheses have received much attention due to their potential implications for biodiversity conservation, however, animal studies have traditionally been their main focus. Here we assess variation in species sensitivity to forest amount and fragmentation and evaluate if fragmentation is related to extinction thresholds in forest understory herbs and ferns. Our expectation was that forest herbs would be more sensitive to fragmentation than ferns due to their lower dispersal capabilities. Using forest cover percentage and the proportion of this percentage occurring in the largest patch within UTM cells of 10-km resolution covering Peninsular Spain, we partitioned the effects of forest amount versus fragmentation and applied logistic regression to model occurrences of 16 species. For nine models showing robustness according to a set of quality criteria we subsequently defined two empirical fragmentation scenarios, minimum and maximum, and quantified species' sensitivity to forest contraction with no fragmentation, and to fragmentation under constant forest cover. We finally assessed how the extinction threshold of each species (the habitat amount below which it cannot persist varies under no and maximum fragmentation. Consistent with their preference for forest habitats probability occurrences of all species decreased as forest cover contracted. On average, herbs did not show significant sensitivity to fragmentation whereas ferns were favored. In line with theory, fragmentation yielded higher extinction thresholds for two species. For the remaining species, fragmentation had either positive or non-significant effects. We interpret these differences as reflecting species-specific traits and conclude that although

Transpiration and CO2 fluxes of a pine forest: modelling the undergrowth effect

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V. Rivalland

2005-02-01

Full Text Available A modelling study is performed in order to quantify the relative effect of allowing for the physiological properties of an undergrowth grass sward on total canopy water and carbon fluxes of the Le-Bray forest (Les-Landes, South-western France. The Le-Bray forest consists of maritime pine and an herbaceous undergrowth (purple moor-grass, which is characterised by a low stomatal control of transpiration, in contrast to maritime pine. A CO2-responsive land surface model is used that includes responses of woody and herbaceous species to water stress. An attempt is made to represent the properties of the undergrowth vegetation in the land surface model Interactions between Soil, Biosphere, and Atmosphere, CO2-responsive, ISBA-A-gs. The new adjustment allows for a fairly different environmental response between the forest canopy and the understory in a simple manner. The model's simulations are compared with long term (1997 and 1998 micro-meteorological measurements over the Le-Bray site. The fluxes of energy, water and CO2, are simulated with and without the improved representation of the undergrowth vegetation, and the two simulations are compared with the observations. Accounting for the undergrowth permits one to improve the model's scores. A simple sensitivity experiment shows the behaviour of the model in response to climate change conditions, and the understory effect on the water balance and carbon storage of the forest. Accounting for the distinct characteristics of the undergrowth has a substantial and positive effect on the model accuracy and leads to a different response to climate change scenarios.

Response of vegetation indices to changes in three measures of leaf water stress

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Cohen, Warren B.

1991-01-01

The responses of vegetation indices to changes in water stress were evaluated in two separate laboratory experiments. In one experiment the normalized difference vegetation index (NDVI), the near-IR to red ratio (near-IR/red), the Infrared Index (II), and the Moisture Stress Index (MSI) were more highly correlated to leaf water potential in lodgepole pine branches than were the Leaf Water Content Index (LWCI), the mid-IR ratio (Mid-IR), or any of the single Thematic Mapper (TM) bands. In the other experiment, these six indices and the TM Tasseled Cap brightness, greenness, and wetness indices responded to changes in leaf relative water content (RWC) differently than they responded to changes in leaf water content (WC) of three plant species, and the responses were dependent on how experimental replicates were pooled. With no pooling, the LWCI was the most highly correlated index to both RWC and WC among replications, followed by the II, MSI, and wetness. Only the LWCI was highly correlated to RWC and WC when replications were pooled within species. With among species pooling the LWCI was the only index highly correlated with RWC, while the II, MSI, Mid-IR, and wetness were most highly correlated with WC.

Impacts of Vegetation Growth on Reach-scale Flood Hydraulics in a Sand-bed River and the Implications for Vegetation-morphology Coevolution

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Box, S.; Wilcox, A. C.

2017-12-01

Vegetation alters flood hydraulics and geomorphic response, yet quantifying and predicting such responses across spatial and temporal scales remains challenging. Plant- and patch-scale studies consistently show that vegetation increases local hydraulic variability, yet reach-scale hydrodynamic models often assume vegetation has a spatially homogeneous effect on hydraulics. Using Nays2DH in iRIC (International River Interface Cooperative), we model the effect of spatially heterogeneous vegetation on a series of floods with varying antecedent vegetation conditions in a sand-bed river in western Arizona, taking advantage of over a decade of data on a system that experienced substantial geomorphic, hydrologic, and ecosystem changes. We show that pioneer woody seedlings (Tamarix, Populus, Salix) and cattail (Typha) increase local hydraulic variability, including velocity and bed shear stress, along individual cross sections, predominantly by decreasing velocity in zones of vegetation establishment and growth and increasing velocity in unvegetated areas, with analogous effects on shear stress. This was especially prominent in a study reach where vegetation growth contributed to thalweg incision relative to a vegetated bar. Evaluation of these results in the context of observed geomorphic response to floods elucidates mechanisms by which vegetation and channel morphology coevolve at a reach scale. By quantifying the influence of spatially heterogeneous vegetation on reach-scale hydraulics, we demonstrate that plant- and patch-scale research on vegetation hydraulics is applicable to ecogeomorphology at the reach scale.

Should Exotic Eucalyptus be Planted in Subtropical China: Insights from Understory Plant Diversity in Two Contrasting Eucalyptus Chronosequences.

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Wu, Jianping; Fan, Houbao; Liu, Wenfei; Huang, Guomin; Tang, Jianfu; Zeng, Ruijin; Huang, Jing; Liu, Zhanfeng

2015-11-01

Although Eucalyptus is widely planted in South China, whose effects on native biodiversity are unclear. The objective of this study was to quantify the richness and composition of understory plants in two contrasting Eucalyptus chronosequences in South China. One was in Zhangzhou City with plantation age of 2, 4, and 6 years after clear-cutting Chinese fir forests, while the other was in Heshan City with plantation age of 2, 3, and 24 years that reforested on barren lands. Results showed that the richness of understory plants and functional groups was not significantly altered in the Zhangzhou chronosequence, while increased in the 24-year-old plantations, with a significantly larger proportion of woody plants than the younger plantations for the Heshan chronosequence. Moreover, a higher richness of woody plants accompanied by a lower richness of herbaceous species was detected in the Zhangzhou chronosequence compared with the Heshan one. To balance the need for pulp production and plant diversity conservation, we suggest that intercropping approaches between exotic Eucalyptus plantations and native forests should be considered in the fast rotation Eucalyptus plantations. However, Eucalyptus plantations may be used as pioneer species to sustain ecosystem functioning for the degraded lands.

When Winners Become Losers: Predicted Nonlinear Responses of Arctic Birds to Increasing Woody Vegetation.

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Sarah J Thompson

Full Text Available Climate change is facilitating rapid changes in the composition and distribution of vegetation at northern latitudes, raising questions about the responses of wildlife that rely on arctic ecosystems. One widely observed change occurring in arctic tundra ecosystems is an increasing dominance of deciduous shrub vegetation. Our goals were to examine the tolerance of arctic-nesting bird species to existing gradients of vegetation along the boreal forest-tundra ecotone, to predict the abundance of species across different heights and densities of shrubs, and to identify species that will be most or least responsive to ongoing expansion of shrubs in tundra ecosystems. We conducted 1,208 point counts on 12 study blocks from 2012-2014 in northwestern Alaska, using repeated surveys to account for imperfect detection of birds. We considered the importance of shrub height, density of low and tall shrubs (i.e. shrubs >0.5 m tall, percent of ground cover attributed to shrubs (including dwarf shrubs <0.5 m tall, and percent of herbaceous plant cover in predicting bird abundance. Among 17 species considered, only gray-cheeked thrush (Catharus minimus abundance was associated with the highest values of all shrub metrics in its top predictive model. All other species either declined in abundance in response to one or more shrub metrics or reached a threshold where further increases in shrubs did not contribute to greater abundance. In many instances the relationship between avian abundance and shrubs was nonlinear, with predicted abundance peaking at moderate values of the covariate, then declining at high values. In particular, a large number of species were responsive to increasing values of average shrub height with six species having highest abundance at near-zero values of shrub height and abundance of four other species decreasing once heights reached moderate values (≤ 33 cm. Our findings suggest that increases in shrub cover and density will negatively

Trend shifts in satellite-derived vegetation growth in Central Eurasia, 1982-2013.

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Xu, Hao-Jie; Wang, Xin-Ping; Yang, Tai-Bao

2017-02-01

Central Eurasian vegetation is critical for the regional ecological security and the global carbon cycle. However, climatic impacts on vegetation growth in Central Eurasia are uncertain. The reason for this uncertainty lies in the fact that the response of vegetation to climate change showed nonlinearity, seasonality and differences among plant functional types. Based on remotely sensed vegetation index and in-situ meteorological data for the years 1982-2013, in conjunction with the latest land cover type product, we analyzed how vegetation growth trend varied across different seasons and evaluated vegetation response to climate variables at regional, biome and pixel scales. We found a persistent increase in the growing season NDVI over Central Eurasia during 1982-1994, whereas this greening trend has stalled since the mid-1990s in response to increased water deficit. The stalled trend in the growing season NDVI was largely attributed by summer and autumn NDVI changes. Enhanced spring vegetation growth after 2002 was caused by rapid spring warming. The response of vegetation to climatic factors varied in different seasons. Precipitation was the main climate driver for the growing season and summer vegetation growth. Changes in temperature and precipitation during winter and spring controlled the spring vegetation growth. Autumn vegetation growth was mainly dependent on the vegetation growth in summer. We found diverse responses of different vegetation types to climate drivers in Central Eurasia. Forests were more responsive to temperature than to precipitation. Grassland and desert vegetation responded more strongly to precipitation than to temperature in summer but more strongly to temperature than to precipitation in spring. In addition, the growth of desert vegetation was more dependent on winter precipitation than that of grasslands. This study has important implications for improving the performance of terrestrial ecosystem models to predict future vegetation

Analyzing the vegetation response under different treatments after wildfires in NE Spain

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León, Javier; Cerdà, Artemi; Badía, David; Echeverría, Maite; Martí, Clara

2014-05-01

Fire is a natural factor of landscape evolution in Mediterranean ecosystems. The socio-economic changes that occurred in the last decades have contributed to an increase in forest fires (Shakesby, 2011). There was found a change in the fire regimes in terms of frequency, size, seasonality, recurrence as well as fire intensity and severity (Keeley, 2009), which resulted in severe effects on soils, water and vegetation (Guénon et al., 2013). Fire affects soil properties directly by the heat impact (Aznar et al., 2013), and the ash cover (Cerdà and Doerr, 2008) and the reduction of the plant cover (Neary et al., 1999). The lack of vegetation and the heating promotes changes in the soil organic matter content (González-Pérez et al., 2004), on the structural stability (Mataix-Solera et al., 2011), on the hydrophobic response (Bodí et al., 2012), and on the infiltration capacity (Cerdà, 1998a). This is why the vegetation cover and the litter are key factors on soil erosion after forest fires (Prats et al., 2013). Besides, the ash plays an important paper in the soil protection after the forest fire and after the first storms and winds (León et al., 2013; Pereira et al., 2013). The objective of this experiment is to asses the vegetation response after a forest fire and the impact of vegetation recovery on soil erosion. The experiment consisted in a sampling of a linear transect of 10 m with samples each 2 m, under different slope position and aspect. To measure the soil erosion rates we used rainfall simulation experiments (León et al., 2013). The experiments were carried in Castejón (UTM 30T, X671106, Y4644584) in a forest burned in 2008, in the Zuera Mountains, both located in the north of Zaragoza province (NE Spain). The soils on limestone parent material are Rendzic Phaeozem (IUSS, 2007) and the texture of Ah horizons of soils developed on limestone is sandy-loam (Badía et al., 2013). The result shows fast and successful vegetation regeneration in the north

Simulating the vegetation response in western Europe to abrupt climate changes under glacial background conditions

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M.-N. Woillez

2013-03-01

Full Text Available The last glacial period has been punctuated by two types of abrupt climatic events, the Dansgaard–Oeschger (DO and Heinrich (HE events. These events, recorded in Greenland ice and in marine sediments, involved changes in the Atlantic Meridional Overturning Circulation (AMOC and led to major changes in the terrestrial biosphere. Here we use the dynamical global vegetation model ORCHIDEE to simulate the response of vegetation to abrupt changes in the AMOC strength. We force ORCHIDEE offline with outputs from the IPSL_CM4 general circulation model, in which the AMOC is forced to change by adding freshwater fluxes in the North Atlantic. We investigate the impact of a collapse and recovery of the AMOC, at different rates, and focus on Western Europe, where many pollen records are available for comparison. The impact of an AMOC collapse on the European mean temperatures and precipitations simulated by the GCM is relatively small but sufficient to drive an important regression of forests and expansion of grasses in ORCHIDEE, in qualitative agreement with pollen data for an HE event. On the contrary, a run with a rapid shift of the AMOC to a hyperactive state of 30 Sv, mimicking the warming phase of a DO event, does not exhibit a strong impact on the European vegetation compared to the glacial control state. For our model, simulating the impact of an HE event thus appears easier than simulating the abrupt transition towards the interstadial phase of a DO. For both a collapse or a recovery of the AMOC, the vegetation starts to respond to climatic changes immediately but reaches equilibrium about 200 yr after the climate equilibrates, suggesting a possible bias in the climatic reconstructions based on pollen records, which assume equilibrium between climate and vegetation. However, our study does not take into account vegetation feedbacks on the atmosphere.

Differential responses of invasive Celastrus orbiculatus (Celastraceae) and native C. scandens to changes in light quality.

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Leicht, Stacey A; Silander, John A

2006-07-01

When plants are subjected to leaf canopy shade in forest understories or from neighboring plants, they not only experience reduced light quantity, but light quality in lowered red : far red light (R : FR). Growth and other developmental responses of plants in reduced R : FR can vary and are not consistent across species. We compared how an invasive liana, Celastrus orbiculatus, and its closely related native congener, C. scandens, responded to changes in the R : FR under controlled, simulated understory conditions. We measured a suite of morphological and growth attributes under control, neutral shading, and low R : FR light treatments. Celastrus orbiculatus showed an increase in height, aboveground biomass, and total leaf mass in reduced R : FR treatments as compared to the neutral shade, while C. scandens had increased stem diameter, single leaf area, and leaf mass to stem mass ratio. These differences provide a mechanistic understanding of the ability of C. orbiculatus to increase height and actively forage for light resources in forest understories, while C. scandens appears unable to forage for light and instead depends upon a light gap forming. The plastic growth response of C. orbiculatus in shaded conditions points to its success in forested habitats where C. scandens is largely absent.

Climate Change, Glacier Response, and Vegetation Dynamics in the Himalaya: Contributions Toward Future Earth Initiatives

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Joseph Shea

2017-08-01

Full Text Available Reviewed: Climate Change, Glacier Response, and Vegetation Dynamics in the Himalaya: Contributions Toward Future Earth Initiatives. Edited by R. B. Singh, Udo Schickhoff, and Suraj Mal. Cham, Switzerland: Springer, 2016. xvi + 399 pp. Hardcover: US$ 179.00, ISBN 978-3-319-28975-5. E-book: US$ 139.00, ISBN 978-3-319-28977-9.

CORTICAL RESPONSES TO SALIENT NOCICEPTIVE AND NOT NOCICEPTIVE STIMULI IN VEGETATIVE AND MINIMAL CONSCIOUS STATE

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MARINA eDE TOMMASO

2015-01-01

Full Text Available Aims Questions regarding perception of pain in non-communicating patients and the management of pain continue to raise controversy both at a clinical and ethical level. The aim of this study was to examine the cortical response to salient multimodal visual, acoustic, somatosensory electric non nociceptive and nociceptive laser stimuli and their correlation with the clinical evaluation.Methods: Five Vegetative State (VS, 4 Minimally Conscious State (MCS patients and 11 age- and sex-matched controls were examined. Evoked responses were obtained by 64 scalp electrodes, while delivering auditory, visual, non-noxious electrical and noxious laser stimulation, which were randomly presented every 10 sec. Laser, somatosensory, auditory and visual evoked responses were identified as a negative-positive (N2-P2 vertex complex in the 500 msec post-stimulus time. We used Nociception Coma Scale-Revised (NCS-R and Coma Recovery Scale (CRS-R for clinical evaluation of pain perception and consciousness impairment.Results: The laser evoked potentials (LEPs were recognizable in all cases. Only one MCS patient showed a reliable cortical response to all the employed stimulus modalities. One VS patient did not present cortical responses to any other stimulus modality. In the remaining participants, auditory, visual and electrical related potentials were inconstantly present. Significant N2 and P2 latency prolongation occurred in both VS and MCS patients. The presence of a reliable cortical response to auditory, visual and electric stimuli was able to correctly classify VS and MCS patients with 90% accuracy. Laser P2 and N2 amplitudes were not correlated with the CRS-R and NCS-R scores, while auditory and electric related potentials amplitude were associated with the motor response to pain and consciousness recovery. Discussion: pain arousal may be a primary function also in vegetative state patients while the relevance of other stimulus modalities may indicate the

Vegetation response of a dry shrubland community to feral goat management on the island of Moloka‘i, Hawai‘i

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Jacobi, James D.; Stock, Jonathan

2017-12-14

The Hawaiian Islands are well known for their unique ecosystem assemblages that have a high proportion of endemic flora and fauna. However, since human colonization of this archipelago—starting with the arrival of Polynesian sailors approximately 1,200 years ago, and particularly following western contact in 1778—thousands of non-native species have been introduced to the Islands and many of these alien species have had severe impacts on the native ecosystems. Particularly damaging to these ecosystems are large mammals, including goats (Capra hircus), pigs (Sus scrofa), cattle (Bos taurus), deer (Axis axis and Odocoileus hemionus), and sheep (Ovis spp.), which are collectively referred to here as ungulates; they cause extensive damage to the native vegetation by their browsing, grazing, and trampling. Similar impacts have been documented elsewhere, including New Zealand and many other island ecosystems.Previous studies in Hawai‘i have utilized fenced exclosures to assess the impacts of feral or wild ungulates on vegetation and the recovery potential for the native plant communities by comparing plant community composition, structure, and cover inside the fenced area (without ungulates) over time to the vegetation condition outside of the protection of the fence. In some cases, the native vegetation recovered once the animals were removed. However, in other situations alien plants were more competitive and dominated the revegetation process after the impacts of ungulates had been reduced or eliminated.This report describes the response of a highly degraded lowland dry habitat plant community located on the south slope of east Moloka‘i, Hawai‘i, to reduction of browsing and grazing impacts caused by feral goats. For this study, vegetation response inside a fenced exclosure was compared to vegetation change in the area outside of the fence that was still accessible to goats. This study is part of the larger U.S. Geological Survey Ridge-to-Reef (USGS-R2R

The Effect of Restoration Treatments on the Spatial Variability of Soil Processes under Longleaf Pine Trees

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John K. Hiers

2012-08-01

Full Text Available The objectives of this study were to (1 characterize tree-based spatial patterning of soil properties and understory vegetation in frequently burned (“reference state” and fire-suppressed longleaf pine forests; and (2 determine how restoration treatments affected patterning. To attain these objectives, we used an experimental manipulation of management types implemented 15 years ago in Florida. We randomly located six mature longleaf pine trees in one reference and four restoration treatments (i.e., burn, control, herbicide, and mechanical, for a total of 36 trees. In addition to the original treatments and as part of a monitoring program, all plots were subjected to several prescribed fires during these 15 years. Under each tree, we sampled mineral soil and understory vegetation at 1 m, 2 m, 3 m and 4 m (vegetation only away from the tree. At these sites, soil carbon and nitrogen were higher near the trunk while graminoids, forbs and saw palmetto covers showed an opposite trend. Our results confirmed that longleaf pine trees affect the spatial patterning of soil and understory vegetation, and this patterning was mostly limited to the restoration sites. We suggest frequent burning as a probable cause for a lack of spatial structure in the “reference state”. We attribute the presence of spatial patterning in the restoration sites to accumulation of organic materials near the base of mature trees.

Resistance to wildfire and early regeneration in natural broadleaved forest and pine plantation

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Proença, Vânia; Pereira, Henrique M.; Vicente, Luís

2010-11-01

The response of an ecosystem to disturbance reflects its stability, which is determined by two components: resistance and resilience. We addressed both components in a study of early post-fire response of natural broadleaved forest ( Quercus robur, Ilex aquifolium) and pine plantation ( Pinus pinaster, Pinus sylvestris) to a wildfire that burned over 6000 ha in NW Portugal. Fire resistance was assessed from fire severity, tree mortality and sapling persistence. Understory fire resistance was similar between forests: fire severity at the surface level was moderate to low, and sapling persistence was low. At the canopy level, fire severity was generally low in broadleaved forest but heterogeneous in pine forest, and mean tree mortality was significantly higher in pine forest. Forest resilience was assessed by the comparison of the understory composition, species diversity and seedling abundance in unburned and burned plots in each forest type. Unburned broadleaved communities were dominated by perennial herbs (e.g., Arrhenatherum elatius) and woody species (e.g., Hedera hibernica, Erica arborea), all able to regenerate vegetatively. Unburned pine communities presented a higher abundance of shrubs, and most dominant species relied on post-fire seeding, with some species also being able to regenerate vegetatively (e.g., Ulex minor, Daboecia cantabrica). There were no differences in diversity measures in broadleaved forest, but burned communities in pine forest shared less species and were less rich and diverse than unburned communities. Seedling abundance was similar in burned and unburned plots in both forests. The slower reestablishment of understory pine communities is probably explained by the slower recovery rate of dominant species. These findings are ecologically relevant: the higher resistance and resilience of native broadleaved forest implies a higher stability in the maintenance of forest processes and the delivery of ecosystem services.

The response of vegetation structure to active warming and precipitation reduction of the Sphagnum peatland

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Łuców, Dominika; Basińska, Anna; Chojnicki, Bogdan; Gąbka, Maciej; Józefczyk, Damian; Juszczak, Radosław; Leśny, Jacek; Olejnik, Janusz; Reczuga, Monika; Samson, Mateusz; Silvennoinen, Hanna; Stróżecki, Marcin; Urbaniak, Marek; Zielińska, Małgorzata; Lamentowicz, Mariusz

2017-04-01

The recent climate change (e.g. increased temperature and decreased precipitation) is expected to affect biodiversity and vegetation structure of the European peatlands, as well as carbon fluxes. Our experimental study carried out in Western Poland, tests the hypothesis that the increased temperature, in particular in combination with rainfall reduction affects vegetation structure of the Sphagnum peatland, through changes in moss and vascular plants abundance. The innovative climate manipulation system was installed on the Rzecin peatland in 2014. The field site consists of four blocks: "drought" "warming and drought" "warming" and "control". The air and peat temperatures were increased in 2015 and 2016 by about 0.2 oC and 1.0 oC, respectively, using infrared radiators. Precipitation was reduced by automatic curtain operated only during the nights by about 37 % in both years. Data resulting from the analyses of digital pictures as well as Point Intercept method were used to identify changes in vegetation structure as a response to warming and drought. We observed increase in abundance of vascular plant and decrease in abundance of mosses during the very dry 2015 vegetation season. It appeared that Carex spp. (C. limosa and C. rostrata) abundance responded positively to warming, while Sphagnum spp. (S. angustifolium and S. teres) responded negatively. The "warming" block was characterized by an increase in abundance of Carex spp. by 8.3 % to 16.7 % and decreased abundance of Sphagnum spp. from 25 % to 19.4 %, whereas in the block of "warming and drought" 11.4 % to by 18.3 and 38 % to 26.9 %, respectively in the August 2015. However, we observed decrease in Sphagnum spp. abundance in the treatment with rainfall reduction in wetter 2016, and their increase in the control. Our results show how considerable changes in vegetation structure can be expected under the stress of warming and modified rainfall conditions, even after a short-term manipulation. However, it is

Windthrow and salvage logging in an old-growth hemlock-northern hardwoods forest

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Lang, K.D.; Schulte, L.A.; Guntenspergen, G.R.

2009-01-01

Although the initial response to salvage (also known as, post-disturbance or sanitary) logging is known to vary among system components, little is known about longer term forest recovery. We examine forest overstory, understory, soil, and microtopographic response 25 years after a 1977 severe wind disturbance on the Flambeau River State Forest in Wisconsin, USA, a portion of which was salvage logged. Within this former old-growth hemlock-northern hardwoods forest, tree dominance has shifted from Eastern hemlock (Tsuga canadensis) to broad-leaf deciduous species (Ulmus americana, Acer saccharum, Tilia americana, Populus tremuloides, and Betula alleghaniensis) in both the salvaged and unsalvaged areas. While the biological legacies of pre-disturbance seedlings, saplings, and mature trees were initially more abundant in the unsalvaged area, regeneration through root suckers and stump sprouts was common in both areas. After 25 years, tree basal area, sapling density, shrub layer density, and seedling cover had converged between unsalvaged and salvaged areas. In contrast, understory herb communities differed between salvaged and unsalvaged forest, with salvaged forest containing significantly higher understory herb richness and cover, and greater dominance of species benefiting from disturbance, especially Solidago species. Soil bulk density, pH, organic carbon content, and organic nitrogen content were also significantly higher in the salvaged area. The structural legacy of tip-up microtopography remains more pronounced in the unsalvaged area, with significantly taller tip-up mounds and deeper pits. Mosses and some forest herbs, including Athyrium filix-femina and Hydrophyllum virginianum, showed strong positive responses to this tip-up microrelief, highlighting the importance of these structural legacies for understory biodiversity. In sum, although the pathways of recovery differed, this forest appeared to be as resilient to the compound disturbances of windthrow

Biomass Accumulation and Net Primary Production during the Early Stage of Secondary Succession after a Severe Forest Disturbance in Northern Japan

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Tomotsugu Yazaki

2016-11-01

Full Text Available Quantitative evaluations of biomass accumulation after disturbances in forests are crucially important for elucidating and predicting forest carbon dynamics in order to understand the carbon sink/source activities. During early secondary succession, understory vegetation often affects sapling growth. However, reports on biomass recovery in naturally-regenerating sites are limited in Japan. Therefore, we traced annual or biennial changes in plant species, biomass, and net primary production (NPP in a naturally regenerating site in Japan after windthrow and salvage-logging plantation for nine years. The catastrophic disturbance depleted the aboveground biomass (AGB from 90.6 to 2.7 Mg·ha−1, changing understory dominant species from Dryopteris spp. to Rubus idaeus. The mean understory AGB recovered to 4.7 Mg·ha−1 in seven years with the dominant species changing to invasive Solidago gigantea. Subsequently, patches of deciduous trees (mainly Betula spp. recovered whereas the understory AGB decreased. Mean understory NPP increased to 272 g·C·m−2·year−1 within seven years after the disturbance, but decreased thereafter to 189 g·C·m−2·year−1. Total NPP stagnated despite increasing overstory NPP. The biomass accumulation is similar to that of naturally regenerating sites without increase of trees in boreal and temperate regions. Dense ground vegetation and low water and nutrient availability of the soil in the study site restrict the recovery of canopy-forming trees and eventually influence the biomass accumulation.

River ecosystem response to prescribed vegetation burning on Blanket Peatland.

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Brown, Lee E; Johnston, Kerrylyn; Palmer, Sheila M; Aspray, Katie L; Holden, Joseph

2013-01-01

Catchment-scale land-use change is recognised as a major threat to aquatic biodiversity and ecosystem functioning globally. In the UK uplands rotational vegetation burning is practised widely to boost production of recreational game birds, and while some recent studies have suggested burning can alter river water quality there has been minimal attention paid to effects on aquatic biota. We studied ten rivers across the north of England between March 2010 and October 2011, five of which drained burned catchments and five from unburned catchments. There were significant effects of burning, season and their interaction on river macroinvertebrate communities, with rivers draining burned catchments having significantly lower taxonomic richness and Simpson's diversity. ANOSIM revealed a significant effect of burning on macroinvertebrate community composition, with typically reduced Ephemeroptera abundance and diversity and greater abundance of Chironomidae and Nemouridae. Grazer and collector-gatherer feeding groups were also significantly less abundant in rivers draining burned catchments. These biotic changes were associated with lower pH and higher Si, Mn, Fe and Al in burned systems. Vegetation burning on peatland therefore has effects beyond the terrestrial part of the system where the management intervention is being practiced. Similar responses of river macroinvertebrate communities have been observed in peatlands disturbed by forestry activity across northern Europe. Finally we found river ecosystem changes similar to those observed in studies of wild and prescribed forest fires across North America and South Africa, illustrating some potentially generic effects of fire on aquatic ecosystems.

Short-term responses of wetland vegetation after liming of an Adirondack watershed

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Mackun, I.R.; Leopold, D.J.; Raynal, D.J. (State Univ. of New York, Syracuse, NY (United States))

1994-08-01

Watershed liming has been suggested as a long-term mitigation strategy for lake acidity, particularly in areas subject to high levels of acidic deposition. However, virtually no information has been available on the impacts of liming on wetland vegetation. In 1989, 1100 Mg of limestone (83.5% CaCO[sub 3]) were aerially applied to 48% (100 ha) of the Woods Lake watershed in the west-central Adirondack region of New York as part of the first comprehensive watershed liming study in North America. We inventoried wetland vegetation in 1.0-m[sup 2] plots before liming and during the subsequent 2 yr. Within this period liming influenced the cover, frequency, or importance values of only 6 of 64 wetland taxa. The cover of Sphagnum spp. and of the cespitose sedge Carex interior decreased in control relative to limed plots, and cover of the rhizomatous sedge Cladium mariscoides increased nearly threefold in limed areas. These two sedges, which are relatively tall, are characteristic of more calcareous habitats. Cover of the grass Muhlenbergia uniflora, cover and importance were adversely affected or inhibited by lime. It is unclear whether liming directly inhibited the growth of these three small-statured species, or whether the adverse effects of lime were mediated through shifts in competitive interactions with other species. The limited responses that we observed to liming, along with changes that occurred in control plots over the study period, may indicate that in the short term watershed liming was no more of a perturbation than the environmental factors responsible for natural annual variation in wetland communities.

Rapid continental-scale vegetation response to the Younger Dryas Cool Episode

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Peros, M.; Gajewski, K.; Viau, A.

2006-12-01

The Younger Dryas Cool Episode had rapid and widespread effects on flora and fauna throughout the Americas. Fossil pollen records document how plant communities responded to this event, although such data are generally only representative of changes at local- to regional-scales. We use a new approach to provide insight into vegetation responses to the Younger Dryas at a continental-scale, by focusing on data extracted for a single taxon (Populus poplar, cottonwood, aspen) from pollen diagrams throughout North America. We show that Populus underwent a rapid and continent-wide decline as the climate rapidly cooled and dried. At the termination of the Younger Dryas, Populus underwent another widespread decline, this time in response to competition from boreal and temperate taxa as the climate abruptly warmed. Late glacial-early Holocene pollen assemblages with high quantities of Populus pollen often lack modern analogues and thus confound quantitative paleoclimatic reconstructions; our results provide a context to interpret these assemblages. Furthermore, while Populus may continue to expand in the future in response to human disturbance and increasing temperatures, its sensitivity to competition may eventually put it at risk as global warming accelerates.

Consumer attitudes towards vegetable attributes: potential buyers of pesticide-free vegetables in Accra and Kumasi, Ghana.

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Probst, Lorenz; Aigelsperger, Lisa; Hauser, Michael

2010-01-01

Considering the inappropriate use of synthetic pesticides on vegetables in West Africa, the rationale behind this research was to assess the extent to which consumers can function as demanders of risk reduced vegetables and hence act as innovators towards vegetable safety. Using the cases of Kumasi and Accra in Ghana, the study examined possible consumer responses to product certification that communicates freedom from pesticides (e.g., organic certification). Generally, search attributes such as the fresh and healthy appearance of a vegetable were found to be central to consumer choice. While consumers stress the importance of health value, they are mostly unaware of agro-chemical risks related to vegetable consumption.

Contrasting germination responses to vegetative canopies experienced in pre- vs. post-dispersal environments

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Leverett, Lindsay D.; Auge, Gabriela A.; Bali, Aman; Donohue, Kathleen

2016-01-01

Background Seeds adjust their germination based on conditions experienced before and after dispersal. Post-dispersal cues are expected to be more accurate predictors of offspring environments, and thus offspring success, than pre-dispersal cues. Therefore, germination responses to conditions experienced during seed maturation may be expected to be superseded by responses to conditions experienced during seed imbibition. In taxa of disturbed habitats, neighbours frequently reduce the performance of germinants. This leads to the hypotheses that a vegetative canopy will reduce germination in such taxa, and that a vegetative canopy experienced during seed imbibition will over-ride germination responses to a canopy experienced during seed maturation, since it is a more proximal cue of immediate competition. These hypotheses were tested here in Arabidopsis thaliana. Methods Seeds were matured under a simulated canopy (green filter) or white light. Fresh (dormant) seeds were imbibed in the dark, white light or canopy at two temperatures (10 or 22 °C), and germination proportions were recorded. Germination was also recorded in after-ripened (less dormant) seeds that were induced into secondary dormancy and imbibed in the dark at each temperature, either with or without brief exposure to red and far-red light. Key Results Unexpectedly, a maturation canopy expanded the conditions that elicited germination, even as seeds lost and regained dormancy. In contrast, an imbibition canopy impeded or had no effect on germination. Maturation under a canopy did not modify germination responses to red and far-red light. Seed maturation under a canopy masked genetic variation in germination. Conclusions The results challenge the hypothesis that offspring will respond more strongly to their own environment than to that of their parents. The observed relaxation of germination requirements caused by a maturation canopy could be maladaptive for offspring by disrupting germination responses

Yield Responses of Black Spruce to Forest Vegetation Management Treatments: Initial Responses and Rotational Projections

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Peter F. Newton

2012-01-01

Full Text Available The objectives of this study were to (1 quantitatively summarize the early yield responses of black spruce (Picea mariana (Mill. B.S.P. to forest vegetation management (FVM treatments through a meta-analytical review of the scientific literature, and (2 given (1, estimate the rotational consequences of these responses through model simulation. Based on a fixed-effects meta-analytic approach using 44 treated-control yield pairs derived from 12 experiments situated throughout the Great Lakes—St. Lawrence and Canadian Boreal Forest Regions, the resultant mean effect size (response ratio and associated 95% confidence interval for basal diameter, total height, stem volume, and survival responses, were respectively: 54.7% (95% confidence limits (lower/upper: 34.8/77.6, 27.3% (15.7/40.0, 198.7% (70.3/423.5, and 2.9% (−5.5/11.8. The results also indicated that early and repeated treatments will yield the largest gains in terms of mean tree size and survival. Rotational simulations indicated that FVM treatments resulted in gains in stand-level operability (e.g., reductions of 9 and 5 yr for plantations established on poor-medium and good-excellent site qualities, resp.. The challenge of maintaining coniferous forest cover on recently disturbed sites, attaining statutory-defined free-to-grow status, and ensuring long-term productivity, suggest that FVM will continue to be an essential silvicultural treatment option when managing black spruce plantations.

Changes in Soil Carbon Stocks and Fluxes in Response to Altered Above- and Belowground Vegetation Inputs

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Marañón-Jiménez, S.; Schuetze, C.; Cuntz, M.; García-Quirós, I.; Dienstbach, L.; Schrumpf, M.; Rebmann, C.

2016-12-01

The stimulation of vegetation productivity in response to rising atmospheric CO2 concentrations can potentially compensate climate change feedbacks. However, this will depend on the allocation of C resources of vegetation into biomass production versus root exudates and on the feedbacks with soil microorganisms. These dynamic adjustments of vegetation will result on changes in above- and belowground productivity and on the amount of C exported to root exudates. Consequent alteration of litter and rhizosphere detritus inputs to the soil and their interaction on controlling soil C sequestration capacity has been, however, rarely assessed. We hypothesize that above- and belowground vegetation exert a synergistic control of soil CO2 emissions, and that the activation of soil organic matter mineralization by the addition of labile organic substrates (i.e.: the priming effect) is altered by changes in the amount and in the quality of the carbon inputs. In order to elucidate these questions, different levels of litter addition were implemented on trenched (root exclusion) and non-trenched plots (with roots) in a temperate deciduous forest. Changes in the sensitivity of soil respiration to temperature and moisture were detected by measuring CO2 fluxes continuously at high temporal resolution with automatic chambers, whereas the spatial and seasonal variability was determined using portable chambers. Annual changes in soil carbon and nitrogen stocks provide additional information on the soil carbon sequestration in response to above- and belowground inputs. Both roots and litter inputs significantly enhanced soil CO2 effluxes soon after the implementation of the experiment. We detected synergistic effects between roots and litter inputs on soil CO2 emissions: When roots were present, carbon mineralized in response to litter addition was much higher than the total amount of carbon added in litter (ca. 170 g C m-2 y-1). Preliminary results of this study suggest that labile

Effects of thinning, burning, seeding, and slash arrangements on understory communities in pinyon-juniper woodlands of northern Arizona

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Maria Irwin

2011-11-01

Full Text Available Pinyon-juniper woodlands are a dominant ecosystem in the American Southwest that have been increasing in density over the last century, generating concerns about the effects on wildlife habitat, livestock forage, and wildfire risk. We tested 16 treatment combinations designed to restore stands to historic conditions by examining the impact on understory plant richness and abundance. We thinned three sites comprised of different parent soil materials: limestone, sandstone, and basalt. Each site had one of four slash arrangements: piled, broadcast, clustered, or no thinning. Each of these arrangements received a different burning/seeding treatment: prescribed fire, seeding, prescribed fire and seeding, or none. This study corresponded with the driest period in the last 55 years, and plant species richness decreased by an average of 40% from the previous year in the control plots. Richness was significantly different due to slash arrangement at the basalt site only. Burning or seeding did not affect richness at any of the sites. Plant species abundance was generally low and not influenced by treatment or site. This study demonstrates that extensive ecosystem manipulation in the pinyon-juniper woodlands of northern Arizona did not affect understory richness or abundance the first year after treatment during a drought.

Effects of thinning, burning, seeding, and slash arrangements on understory communities in pinyon-juniper woodlands of northern Arizona

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Maria R. Irwin

2011-06-01

Full Text Available Pinyon-juniper woodlands are a dominant ecosystem in the American Southwest that have been increasing in density over the last century, generating concerns about the effects on wildlife habitat, livestock forage, and wildfire risk. We tested 16 treatment combinations designed to restore stands to historic conditions by examining the impact on understory plant richness and abundance. We thinned three sites comprised of different parent soil materials: limestone, sandstone, and basalt. Each site had one of four slash arrangements: piled, broadcast, clustered, or no thinning. Each of these arrangements received a different burning/seeding treatment: prescribed fire, seeding, prescribed fire and seeding, or none. This study corresponded with the driest period in the last 55 years, and plant species richness decreased by an average of 40% from the previous year in the control plots. Richness was significantly different due to slash arrangement at the basalt site only. Burning or seeding did not affect richness at any of the sites. Plant species abundance was generally low and not influenced by treatment or site. This study demonstrates that extensive ecosystem manipulation in the pinyon-juniper woodlands of northern Arizona did not affect understory richness or abundance the first year after treatment during a drought.

Response of Vegetation to Climate Change in the Drylands of East Asia

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Dai, L; Wang, K; Wang, R L; Zhang, L

2014-01-01

Over the past 25 years, global climate and environmental changes have caused an unprecedented rate of vegetation change, as exemplified in the drylands of East Asia. In this study, we investigated the spatio-temporal changes of vegetation in this region and analysed their relationship with climate data. Our results show that vegetation productivity significantly increased from 1982 to 2006. This increasing trend was observed for most of the region, particularly for northwest Mongolia and central Inner Mongolia. Grasslands, croplands, forests, and shrublands, all exhibited this trend. The annual growth rate of the grasslands determined using the Normalized Difference Vegetation Index (NDVI) was the largest observed change; reaching 0.07% p.a, followed by shrublands (0.06%), croplands (0.03%), and forests (0.02%). In the different geographic regions, the roles of temperature and precipitation on vegetation growth were shown to be different. Temperature was the dominant factor for the observed NDVI increase in northwest Mongolia and the centre of Inner Mongolia. The combined influences of temperature and precipitation changes have resulted in the promotion of vegetation growth, as seen in eastern GanSu. Temperature change is the primary factor for initiating vegetation growth in spring and autumn because warmer temperatures increase the length of the growing season, and are thus evaluated as an increased NDVI value. Increased precipitation has been shown to play a positive role on vegetation growth during summer

Terrestrial Water Storage and Vegetation Resilience to Drought

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Meyer, V.; Reager, J. T., II; Konings, A. G.

2017-12-01

The expected increased occurrences of hydrologic extreme events such as droughts in the coming decades motivates studies to better understand and predict the response of vegetation to such extreme conditions. Previous studies have addressed vegetation resilience to drought, defined as its ability to recover from a perturbation (Hirota et al., 2011; Vicente-Serrano et al., 2012), but appear to only focus on precipitation and a couple of vegetation indices, hence lacking a key element: terrestrial water storage (TWS). In this study, we combine and compare multiple remotely-sensed hydro-ecological datasets providing information on climatic and hydrological conditions (Tropical Rainfall Measuring Mission (TRMM), Gravity Recovery and Climate Experiment (GRACE)) and indices characterizing the state of the vegetation (vegetation water content using Vegetation Optical Depth (VOD) from SMAP (Soil Moisture Active and Passive), Gross Primary Production (GPP) from FluxCom and Specific Fluorescence Intensity (SFI, from GOSat)) to assess the ability of vegetation to face and recover from droughts across the globe. Our results suggest that GRACE hydrological data bridge the knowledge gap between precipitation deficit and vegetation response. All products are aggregated at a 0.5º spatial resolution and a monthly temporal resolution to match the GRACE Mascon product. Despite these coarse spatiotemporal resolutions, we find that the relationship between existing remotely-sensed eco-hydrologic data varies spatially, both in terms of strength of relationship and time lag, showing the response time of vegetation characteristics to hydrological changes and highlighting the role of water storage. A special attention is given to the Amazon river basin, where two well documented droughts occurred in 2005 and 2010, and where a more recent drought occurred in 2015/2016. References : Hirota, Marina, et al. "Global resilience of tropical forest and savanna to critical transitions." Science

Vegetation Response to Upper Pliocene Glacial/Interglacial Cyclicity in the Central Mediterranean

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Combourieu-Nebout, Nathalie

1993-09-01

New detailed pollen analysis of the lower part of the Upper Pliocene Semaforo section (Crotone, Italy) documents cyclic behavior of vegetation at the beginning of the Northern Hemisphere glaciations. The competition between four vegetation units (subtropical humid forest, deciduous temperate forest, altitudinal coniferous forest, and open xeric assemblage) probably reflects modifications of vegetation belts at this montane site. Several increases in herbaceous open vegetation regularly alternate with subtropical humid forest, which expresses rapid climatic oscillations. The complete temporal succession—deciduous forest (rich in Quercus), followed by subtropical humid forest (Taxodiaceae and Cathaya), then altitudinal coniferous forest ( Tsuga, Cedrus, Abies, and Picea), and finally herbaceous open vegetation (Graminae, Compositae, and Artemisia )—displays the climatic evolution from warm and humid interglaciation to cold and dry glaciation. It also suggests an independent variation of temperature and humidity, the two main climatic parameters. The vegetation history of southern Calabria recorded in the Semaforo section have been correlated with the ∂ 18O signal established in the Atlantic Ocean.

Intake of fruit and vegetables and risk of bladder cancer: a dose-response meta-analysis of observational studies.

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Yao, Baodong; Yan, Yujie; Ye, Xianwu; Fang, Hong; Xu, Huilin; Liu, Yinan; Li, Sheran; Zhao, Yanping

2014-12-01

Observational studies suggest an association between fruit and vegetables intake and risk of bladder cancer, but the results are controversial. We therefore summarized the evidence from observational studies in categorical, linear, and nonlinear, dose-response meta-analysis. Pertinent studies were identified by searching EMBASE and PubMed from their inception to August 2013. Thirty-one observational studies involving 12,610 cases and 1,121,649 participants were included. The combined rate ratio (RR, 95 % CI) of bladder cancer for the highest versus lowest intake was 0.83 (0.69-0.99) for total fruit and vegetables, 0.81 (0.70-0.93) for total vegetables, 0.77 (0.69-0.87) for total fruit, 0.84 (0.77-0.91) for cruciferous vegetables, 0.79 (0.68-0.91) for citrus fruits, and 0.74 (0.66-0.84) for yellow-orange vegetables. Subgroup analysis showed study design and gender as possible sources of heterogeneity. A nonlinear relationship was found of citrus fruits intake with risk of bladder cancer (P for nonlinearity = 0.018), and the RRs (95 % CI) of bladder cancer were 0.87 (0.78-0.96), 0.80 (0.67-0.94), 0.79 (0.66-0.94), 0.79 (0.65-0.96), and 0.79 (0.64-0.99) for 30, 60, 90, 120, and 150 g/day. A nonlinear relationship was also found of yellow-orange vegetable intake with risk of bladder cancer risk (P for nonlinearity = 0.033). Some evidence of publication bias was observed for fruit, citrus fruits, and yellow-orange vegetables. This meta-analysis supports the hypothesis that intakes of fruit and vegetables may reduce the risk of bladder cancer. Future well-designed studies are required to confirm this finding.

Vegetation morphologic and aerodynamic characteristics reduce aeolian erosion.

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Miri, Abbas; Dragovich, Deirdre; Dong, Zhibao

2017-10-09

Vegetation cover is crucial to controlling aeolian erosion but highly efficient vegetation is critical. How this efficiency is influenced by vegetation response to airflow is not clear. Here we evaluate the responses of Cosmos bipinnatus and Ligustrum lucidum Ait to a range of wind speeds in a wind tunnel. For both species, we calculate shelter effect and sand flux. We show that plant effectiveness in reducing wind speed and sediment transport is linked to their aerodynamic response to airflow which results from their morphology. We demonstrate that in low-density cover the flow-response and resistance of individuals is most critical in the optimal effectiveness of a canopy. Our wind tunnel experiment suggests that vegetation morphology and structure must be priority parameters in facilitating aeolian erosion control.

A synopsis of short-term response to alternative restoration treatments in sagebrush-steppe: the SageSTEP project

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McIver, James; Brunson, Mark; Bunting, Steve; Chambers, Jeanne; Doescher, Paul; Grace, James; Hulet, April; Johnson, Dale; Knick, Steven T.; Miller, Richard; Pellant, Mike; Pierson, Fred; Pyke, David; Rau, Benjamin; Rollins, Kim; Roundy, Bruce; Schupp, Eugene; Tausch, Robin; Williams, Jason

2014-01-01

The Sagebrush Steppe Treatment Evaluation Project (SageSTEP) is an integrated long-term study that evaluates ecological effects of alternative treatments designed to reduce woody fuels and to stimulate the herbaceous understory of sagebrush steppe communities of the Intermountain West. This synopsis summarizes results through 3 yr posttreatment. Woody vegetation reduction by prescribed fire, mechanical treatments, or herbicides initiated a cascade of effects, beginning with increased availability of nitrogen and soil water, followed by increased growth of herbaceous vegetation. Response of butterflies and magnitudes of runoff and erosion closely followed herbaceous vegetation recovery. Effects on shrubs, biological soil crust, tree cover, surface woody fuel loads, and sagebrush-obligate bird communities will take longer to be fully expressed. In the short term, cool wet sites were more resilient than warm dry sites, and resistance was mostly dependent on pretreatment herbaceous cover. At least 10 yr of posttreatment time will likely be necessary to determine outcomes for most sites. Mechanical treatments did not serve as surrogates for prescribed fire in how each influenced the fuel bed, the soil, erosion, and sage-obligate bird communities. Woody vegetation reduction by any means resulted in increased availability of soil water, higher herbaceous cover, and greater butterfly numbers. We identified several trade-offs (desirable outcomes for some variables, undesirable for others), involving most components of the study system. Trade-offs are inevitable when managing complex natural systems, and they underline the importance of asking questions about the whole system when developing management objectives. Substantial spatial and temporal heterogeneity in sagebrush steppe ecosystems emphasizes the point that there will rarely be a “recipe” for choosing management actions on any specific area. Use of a consistent evaluation process linked to monitoring may be the

Differences in Plant Traits among N-fixing Trees in Hawaii Affect Understory Nitrogen Cycling

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August-Schmidt, E.; D'Antonio, C. M.

2016-12-01

Nitrogen (N) fixing trees are frequently used to restore soil functions to degraded ecosystems because they can increase soil organic matter and N availability. Although N-fixers are lumped into a single functional group, the quality and quantity of the plant material they produce and the rate at which they accrete and add N to the cycling pool likely vary. This talk will focus on the questions: (1) How does N-cycling differ among N-fixing tree species? And (2) Which plant traits are most important in distinguishing the soil N environment? To address these questions, we investigated planted stands of two Hawaiian native N-fixing trees (Acacia koa and Sophora chrysophylla) and `natural' stands of an invasive N-fixing tree (Morella faya) in burned seasonal submontane woodlands in Hawaii Volcanoes National Park. We measured the relative availability of nitrogen in the soil pool and understory plant community as well as characterizing the rate and amount of N cycling in these stands both in the field and using long term soil incubations in the laboratory. We found that N is cycled very differently under these three N-fixers and that this correlates with differences in their leaf traits. S. chrysophylla had the highest foliar %N and highest specific leaf area, and stands of these trees are associated with faster N-cycling, resulting in greater N availability compared to all other site types. Incubated S. chrysophylla soils mineralized almost twice as much N as any other soil type over the course of the experiment. The comparatively high-N environment under S. chrysophylla suggests that litter quality may be more important than litter quantity in determining nitrogen availability to the understory community.

Dynamic Response of Satellite-Derived Vegetation Growth to Climate Change in the Three North Shelter Forest Region in China

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Bin He

2015-08-01

Full Text Available Since the late 1970s, the Chinese government has initiated ecological restoration programs in the Three North Shelter Forest System Project (TNSFSP area. Whether accelerated climate change will help or hinder these efforts is still poorly understood. Using the updated and extended AVHRR NDVI3g dataset from 1982 to 2011 and corresponding climatic data, we investigated vegetation variations in response to climate change. The results showed that the overall state of vegetation in the study region has improved over the past three decades. Vegetation cover significantly decreased in 23.1% and significantly increased in 21.8% of the study area. An increase in all three main vegetation types (forest, grassland, and cropland was observed, but the trend was only statistically significant in cropland. In addition, bare and sparsely vegetated areas, mainly located in the western part of the study area, have significantly expanded since the early 2000s. A moisture condition analysis indicated that the study area experienced significant climate variations, with warm-wet conditions in the western region and warm-dry conditions in the eastern region. Correlation analysis showed that variations in the Normalized Difference Vegetation Index (NDVI were positively correlated with precipitation and negatively correlated with temperature. Ultimately, climate change influenced vegetation growth by controlling the availability of soil moisture. Further investigation suggested that the positive impacts of precipitation on NDVI have weakened in the study region, whereas the negative impacts from temperature have been enhanced in the eastern study area. However, over recent years, the negative temperature impacts have been converted to positive impacts in the western region. Considering the variations in the relationship between NDVI and climatic variables, the warm–dry climate in the eastern region is likely harmful to vegetation growth, whereas the warm�

Remote sensing analysis of riparian vegetation response to desert marsh restoration in the Mexican Highlands

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Norman, Laura M.; Villarreal, Miguel; Pulliam, H. Ronald; Minckley, Robert L.; Gass, Leila; Tolle, Cindy; Coe, Michelle

2014-01-01

Desert marshes, or cienegas, are extremely biodiverse habitats imperiled by anthropogenic demands for water and changing climates. Given their widespread loss and increased recognition, remarkably little is known about restoration techniques. In this study, we examine the effects of gabions (wire baskets filled with rocks used as dams) on vegetation in the Cienega San Bernardino, in the Arizona, Sonora portion of the US-Mexico border, using a remote-sensing analysis coupled with field data. The Normalized Difference Vegetation Index (NDVI), used here as a proxy for plant biomass, is compared at gabion and control sites over a 27-year period during the driest months (May/June). Over this period, green-up occurred at most sites where there were gabions and at a few of the control sites where gabions had not been constructed. When we statistically controlled for differences among sites in source area, stream order, elevation, and interannual winter rainfall, as well as comparisons of before and after the initiation of gabion construction, vegetation increased around gabions yet did not change (or decreased) where there were no gabions. We found that NDVI does not vary with precipitation inputs prior to construction of gabions but demonstrates a strong response to precipitation after the gabions are built. Field data describing plant cover, species richness, and species composition document increases from 2000 to 2012 and corroborate reestablished biomass at gabions. Our findings validate that gabions can be used to restore riparian vegetation and potentially ameliorate drought conditions in a desert cienega.

Landscape patterns of understory composition and richness across a moisture and nitrogen mineralization gradient in Ohio (U.S.A.) Quercus forests

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Todd F. Hutchinson; Ralph E.J. Boerner; Louis R. Iverson; Steve Sutherland; Elaine Kennedy Sutherland

1999-01-01

This study quantified relationships of understory vascular plant species composition and richness along environmental gradients over a broad spatial scale in second-growth oak forests in eastern North America. Species frequencies were recorded in 108 25 x 25 m plots in four study sites extending over 70 km in southern Ohio, U.S.A. The plots were stratified into three...

Response characteristics of vegetation and soil environment to permafrost degradation in the upstream regions of the Shule River Basin

International Nuclear Information System (INIS)

Chen Shengyun; Liu Wenjie; Qin Xiang; Liu Yushuo; Ren Jiawen; Qin Dahe; Zhang Tongzuo; Hu Fengzu; Chen Kelong

2012-01-01

Permafrost degradation exhibits striking and profound influences on the alpine ecosystem, and response characteristics of vegetation and soil environment to such degradation inevitably differ during the entire degraded periods. However, up to now, the related research is lacking in the Qinghai–Tibetan Plateau (QTP). For this reason, twenty ecological plots in the different types of permafrost zones were selected in the upstream regions of the Shule River Basin on the northeastern margin of the QTP. Vegetation characteristics (species diversity, community coverage and biomass etc) and topsoil environment (temperature (ST), water content (SW), mechanical composition (SMC), culturable microorganism (SCM), organic carbon (SOC) and total nitrogen (TN) contents and so on), as well as active layer thickness (ALT) were investigated in late July 2009 and 2010. A spatial–temporal shifts method (the spatial pattern that is represented by different types of permafrost shifting to the temporal series that stands for different stages of permafrost degradation) has been used to discuss response characteristics of vegetation and topsoil environment throughout the entire permafrost degradation. The results showed that (1) ST of 0–40 cm depth and ALT gradually increased from highly stable and stable permafrost (H-SP) to unstable permafrost (UP). SW increased initially and then decreased, and SOC content and the quantities of SCM at a depth of 0–20 cm first decreased and then increased, whereas TN content and SMC showed obscure trends throughout the stages of permafrost degradation with a stability decline from H-SP to extremely unstable permafrost (EUP); (2) further, species diversity, community coverage and biomass first increased and then decreased in the stages from H-SP to EUP; (3) in the alpine meadow ecosystem, SOC and TN contents increased initially and then decreased, soil sandy fractions gradually increased with stages of permafrost degradation from substable (SSP

Hotspots of Community Change: Temporal Dynamics Are Spatially Variable in Understory Plant Composition of a California Oak Woodland.

Directory of Open Access Journals (Sweden)

Erica N Spotswood

Full Text Available Community response to external drivers such climate and disturbance can lead to fluctuations in community composition, or to directional change. Temporal dynamics can be influenced by a combination of drivers operating at multiple spatial scales, including external landscape scale drivers, local abiotic conditions, and local species pools. We hypothesized that spatial variation in these factors can create heterogeneity in temporal dynamics within landscapes. We used understory plant species composition from an 11 year dataset from a California oak woodland to compare plots where disturbance was experimentally manipulated with the removal of livestock grazing and a prescribed burn. We quantified three properties of temporal variation: compositional change (reflecting the appearance and disappearance of species, temporal fluctuation, and directional change. Directional change was related most strongly to disturbance type, and was highest at plots where grazing was removed during the study. Temporal fluctuations, compositional change, and directional change were all related to intrinsic abiotic factors, suggesting that some locations are more responsive to external drivers than others. Temporal fluctuations and compositional change were linked to local functional composition, indicating that environmental filters can create subsets of the local species pool that do not respond in the same way to external drivers. Temporal dynamics are often assumed to be relatively static at the landscape scale, provided disturbance and climate are continuous. This study shows that local and landscape scale factors jointly influence temporal dynamics creating hotspots that are particularly responsive to climate and disturbance. Thus, adequate predictions of response to disturbance or to changing climate will only be achieved by considering how factors at multiple spatial scales influence community resilience and recovery.

Hotspots of Community Change: Temporal Dynamics Are Spatially Variable in Understory Plant Composition of a California Oak Woodland.

Science.gov (United States)

Spotswood, Erica N; Bartolome, James W; Allen-Diaz, Barbara

2015-01-01

Community response to external drivers such climate and disturbance can lead to fluctuations in community composition, or to directional change. Temporal dynamics can be influenced by a combination of drivers operating at multiple spatial scales, including external landscape scale drivers, local abiotic conditions, and local species pools. We hypothesized that spatial variation in these factors can create heterogeneity in temporal dynamics within landscapes. We used understory plant species composition from an 11 year dataset from a California oak woodland to compare plots where disturbance was experimentally manipulated with the removal of livestock grazing and a prescribed burn. We quantified three properties of temporal variation: compositional change (reflecting the appearance and disappearance of species), temporal fluctuation, and directional change. Directional change was related most strongly to disturbance type, and was highest at plots where grazing was removed during the study. Temporal fluctuations, compositional change, and directional change were all related to intrinsic abiotic factors, suggesting that some locations are more responsive to external drivers than others. Temporal fluctuations and compositional change were linked to local functional composition, indicating that environmental filters can create subsets of the local species pool that do not respond in the same way to external drivers. Temporal dynamics are often assumed to be relatively static at the landscape scale, provided disturbance and climate are continuous. This study shows that local and landscape scale factors jointly influence temporal dynamics creating hotspots that are particularly responsive to climate and disturbance. Thus, adequate predictions of response to disturbance or to changing climate will only be achieved by considering how factors at multiple spatial scales influence community resilience and recovery.

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...

Impacts of experimentally applied mountain biking and hiking on vegetation and soil of a deciduous forest.

Science.gov (United States)

Thurston, E; Reader, R J

2001-03-01

Many recent trail degradation problems have been attributed to mountain biking because of its alleged capacity to do more damage than other activities, particularly hiking. This study compared the effects of experimentally applied mountain biking and hiking on the understory vegetation and soil of a deciduous forest. Five different intensities of biking and hiking (i.e., 0, 25, 75, 200 and 500 passes) were applied to 4-m-long x 1-m-wide lanes in Boyne Valley Provincial Park, Ontario, Canada. Measurements of plant stem density, species richness, and soil exposure were made before treatment, two weeks after treatment, and again one year after treatment. Biking and hiking generally had similar effects on vegetation and soil. Two weeks after treatment, stem density and species richness were reduced by up to 100% of pretreatment values. In addition, the amount of soil exposed increased by up to 54%. One year later, these treatment effects were no longer detectable. These results indicate that at a similar intensity of activity, the short-term impacts of mountain biking and hiking may not differ greatly in the undisturbed area of a deciduous forest habitat. The immediate impacts of both activities can be severe but rapid recovery should be expected when the activities are not allowed to continue. Implications of these results for trail recreation are discussed.

Exploring the Future of Fuel Loads in Tasmania, Australia: Shifts in Vegetation in Response to Changing Fire Weather, Productivity, and Fire Frequency

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Rebecca Mary Bernadette Harris

2018-04-01

Full Text Available Changes to the frequency of fire due to management decisions and climate change have the potential to affect the flammability of vegetation, with long-term effects on the vegetation structure and composition. Frequent fire in some vegetation types can lead to transformational change beyond which the vegetation type is radically altered. Such feedbacks limit our ability to project fuel loads under future climatic conditions or to consider the ecological tradeoffs associated with management burns. We present a “pathway modelling” approach to consider multiple transitional pathways that may occur under different fire frequencies. The model combines spatial layers representing current and future fire danger, biomass, flammability, and sensitivity to fire to assess potential future fire activity. The layers are derived from a dynamically downscaled regional climate model, attributes from a regional vegetation map, and information about fuel characteristics. Fire frequency is demonstrated to be an important factor influencing flammability and availability to burn and therefore an important determinant of future fire activity. Regional shifts in vegetation type occur in response to frequent fire, as the rate of change differs across vegetation type. Fire-sensitive vegetation types move towards drier, more fire-adapted vegetation quickly, as they may be irreversibly impacted by even a single fire, and require very long recovery times. Understanding the interaction between climate change and fire is important to identify appropriate management regimes to sustain fire-sensitive communities and maintain the distribution of broad vegetation types across the landscape.

Myrmeciza and related antbirds (Aves, Formicariidae as army ant followers

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Edwin O. Willis

1984-01-01

Full Text Available Antbirds of the genera Myrmeciza (including Sipia and Myrmoborus, Gymnocichla, and Sclateria hop near or on the ground in fairly dense vegetation, "pounding" their tails downward. Where dense understory vegetation is widespread and ants move in it for long distances, certain of these antbirds become regular ant followers: M. immaculata and M. fortis in cluttered moist foothill forest from Costa Rica to upper Amazonia; Gymnocichla nudiceps in moist cluttered second growth of Central America to Colombia. Where the forest understory is more open, Myrmeciza species follow ants mainly in cluttered patches: M. exsul in lowland forest west of the Andes, M. myotherina east of the Andes. Myrmeciza or relatives that specialize on water-edge or very dense zones rarely follow ants.

The initial phase of a Longleaf Pine-Wiregrass Savanna restoration: species establishment and community responses.

Energy Technology Data Exchange (ETDEWEB)

Aschenbach, Todd, A; Foster, Bryan, L.; Imm, Donald, W.

2010-09-01

AbstractAbstract The significant loss of the longleaf pine-wiregrass ecosystem in the southeastern United States has serious implications for biodiversity and ecosystem functioning. In response to this loss, we have initiated a long-term and landscape-scale restoration experiment at the 80,125 ha (310 mi2) Department of Energy Savannah River Site (SRS) located near Aiken, South Carolina. Aristida beyrichiana (wiregrass), an important and dominant grass (i.e., a “matrix” species) of the longleaf pine savanna understory, and 31 other herbaceous “non-matrix” species were planted at six locations throughout SRS in 2002 and 2003. Of the 36,056 transplanted seedlings, 75% were still alive in June 2004, while mean 1–2 year survival across all planted species was 48%. Lespedeza hirta (hairy lespedeza) exhibited the greatest overall survival per 3 ×3 m cell at 95%, whereas Schizachyrium spp. (little bluestem) exhibited the greatest mean cover among individual species at 5.9%. Wiregrass survival and cover were significantly reduced when planted with non-matrix species. Aggregate cover of all planted species in restored cells averaged 25.9% in 2006. High rates of survival and growth of the planted species resulted in greater species richness (SR), diversity, and vegetative cover in restored cells. Results suggest that the loss of the longleaf pine-wiregrass ecosystem may be ameliorated through restoration efforts and illustrate the positive impact of restoration plantings on biodiversity and vegetative cover.

Vegetation ecology of eastern white pine and red pine forests in Ontario. Forest fragmentation and biodiversity project technical report No. 11

Energy Technology Data Exchange (ETDEWEB)

Carleton, T.J.

1993-12-31

This study explored changes in understory species composition and floristic diversity in eastern white pine and red pine stands in Ontario in relation to differences in site condition and stand age. It surveyed 170 natural, fire-origin stands containing at least a 10% component of red pine and white pine basal area throughout the Canadian Shield in Ontario during 1991 and 1992. The stands had not been previously logged and ranged in age from 50-300 years. Sampling was conducted using plots of fixed area. Within these plots, subplots were sampled to capture the variety of vegetation that occurred at different scales. Stand-level data were also recorded outside the fixed area plots. Detailed site data were also collected, including information on soils, topography, coarse woody debris (both standing and fallen), and the nature of the forest floor substrates.

Influence of herbicides and felling, fertilization, and prescribed fire on longleaf pine growth and understory vegetation through ten growing seasons and the outcome of an ensuing wildfire

Science.gov (United States)

James D. Haywood

2011-01-01

Restoring longleaf pine (Pinus palustris Mill.) over much of its original range requires artificial regeneration. In central Louisiana, USA, two fertilization levels - No (NF) or Yes (F-36 kg/ha N and 40 kg/ha P) in combination with three vegetation treatments - Check, four prescribed fires (PF), or multi-year vegetation control by herbicidal and mechanical means (IVM...

Effect of long-term understory prescribed burning on standing and down dead woody material in dry upland oak forests

Science.gov (United States)

Polo, John A.; Hallgren, S.W.; Leslie,, David M.

2013-01-01

Dead woody material, long ignored or viewed as a nuisance for forest management, has gained appreciation for its many roles in the forest including wildlife habitat, nutrient storage and cycling, energy for trophic webs, protection of soil, fuel for fire and carbon storage. The growing interest in managing dead woody material has created strong demand for greater understanding of factors controlling amounts and turnover. Prescribed burning, an important management tool, may have strong effects of dead woody material given fire’s capacity to create and consume dead woody material. We determined effects of long-term understory prescribed burning on standing and down woody material in upland oak forests in south-central North America. We hypothesized that as frequency of fire increased in these stands the amount of deadwood would decrease and the fine woody material would decrease more rapidly than coarse woody material. The study was conducted in forests dominated by post oak (Quercus stellata) and blackjack oak (Quercus marilandica) in wildlife management areas where understory prescribed burning had been practiced for over 20 years and the range of burn frequencies was 0 (unburned) fires per decade (FPD) to 4.6 FPD. The amount of deadwood was low compared with more productive forests in southeastern North America. The biomass (24.7 Mg ha-1) and carbon stocks (11.7 Mg ha-1) were distributed among standing dead (22%), coarse woody debris (CWD, dia. > 7.5 cm., 12%), fine woody debris (FWD, dia. prescribed burning influenced the amount and size distribution of standing and down dead woody material. There were two explanations for the lack of a detectable effect. First, a high incidence of severe weather including ice storms and strong winds that produce large amounts of deadwood intermittently in an irregular pattern across the landscape may preclude detecting a strong effect of understory prescribed burning. Second, fire suppression during the first one-half of the

A Guide to Bottomland Hardwood Restoration

Science.gov (United States)

2001-06-01

floristically Ecological Importance of Understory diverse undergrowth may serve to pollinate flowers, Plants including those of trees. Undergrowth vegetation...Herbaceous plants include bedstraw, Variants and associated vegetation. Sycamore- violet, wild carrot, wild lettuce , amsonia, mint, legumes, pecan...elements of bottomland hardwood restoration such as species selection, site preparation, direct seeding, planting of seedlings, and alternative

Differentiate responses of soil structure to natural vegetation and artificial plantation in landslide hazard region of the West Qinling Mountains, China

Science.gov (United States)

Wang, X.; Huang, Z.; Zhao, Y.; Hong, M.

2017-12-01

Natural vegetation and artificial plantation are the most important measures for ecological restoration in soil erosion and landslide hazard-prone regions of China. Previous studies have demonstrated that both measures can significantly change the soil structure and decrease soil and water erosion. Few reports have compared the effects of the two contrasting measures on mechanical and hydrological properties and further tested the differentiate responses of soil structure. In the study areas, two vegetation restoration measures-natural vegetation restoration (NVR) and artificial plantation restoration (APR) compared with control site, with similar topographical and geological backgrounds were selected to investigate the different effects on soil structure based on eight-year ecological restoration projects. The results showed that the surface vegetation played an important role in releasing soil erosion and enhance soil structure stability through change the soil aggregates (SA) and total soil porosity (TSP). The SArestoration and conservation in geological hazard-prone regions.

River flow response to changes in vegetation cover in a South ...

African Journals Online (AJOL)

It was hypothesised in this study that annual river yield (river flow as a fraction of rainfall) in the Molenaars catchment near Paarl, South Africa co-varies with an index of green vegetation cover derived from satellite data (the normalised difference vegetation index, NDVI). The catchment was partitioned into 'upland' and ...

Investigation on the Patterns of Global Vegetation Change Using a Satellite-Sensed Vegetation Index

Directory of Open Access Journals (Sweden)

Ainong Li

2010-06-01

Full Text Available The pattern of vegetation change in response to global change still remains a controversial issue. A Normalized Difference Vegetation Index (NDVI dataset compiled by the Global Inventory Modeling and Mapping Studies (GIMMS was used for analysis. For the period 1982–2006, GIMMS-NDVI analysis indicated that monthly NDVI changes show homogenous trends in middle and high latitude areas in the northern hemisphere and within, or near, the Tropic of Cancer and Capricorn; with obvious spatio-temporal heterogeneity on a global scale over the past two decades. The former areas featured increasing vegetation activity during growth seasons, and the latter areas experienced an even greater amplitude in places where precipitation is adequate. The discussion suggests that one should be cautious of using the NDVI time-series to analyze local vegetation dynamics because of its coarse resolution and uncertainties.

Differential response of vegetation in Hulun Lake region at the northern margin of Asian summer monsoon to extreme cold events of the last deglaciation

Science.gov (United States)

Zhang, Shengrui; Xiao, Jule; Xu, Qinghai; Wen, Ruilin; Fan, Jiawei; Huang, Yun; Yamagata, Hideki

2018-06-01

The response of vegetation to extreme cold events during the last deglaciation is important for assessing the impact of possible extreme climatic events on terrestrial ecosystems under future global warming scenarios. Here, we present a detailed record of the development of regional vegetation in the northern margin of Asian summer monsoon during the last deglaciation (16,500-11,000 cal yr BP) based on a radiocarbon-dated high-resolution pollen record from Hulun Lake, northeast China. The results show that the regional vegetation changed from subalpine meadow-desert steppe to mixed coniferous and deciduous forest-typical steppe during the last deglaciation. However, its responses to the Heinrich event 1 (H1) and the Younger Dryas event (YD) were significantly different: during the H1 event, scattered sparse forest was present in the surrounding mountains, while within the lake catchment the vegetation cover was poor and was dominated by desert steppe. In contrast, during the YD event, deciduous forest developed and the proportion of coniferous forest increased in the mountains, the lake catchment was occupied by typical steppe. We suggest that changes in Northern Hemisphere summer insolation and land surface conditions (ice sheets and sea level) caused temperature and monsoonal precipitation variations that contributed to the contrasting vegetation response during the two cold events. We conclude that under future global warming scenarios, extreme climatic events may cause a deterioration of the ecological environment of the Hulun Lake region, resulting in increased coniferous forest and decreased total forest cover in the surrounding mountains, and a reduction in typical steppe in the lake catchment.

Role of vegetation on river bank accretion

NARCIS (Netherlands)

Vargas Luna, A.

2016-01-01

There is rising awareness of the need to include the effects of vegetation in studies dealing with the morphological response of rivers. Vegetation growth on river banks and floodplains alters the river bed topography, reduces the bank erosion rates and enhances the development of new floodplains

Vulnerability and Resilience of Temperate Forest Landscapes to Broad-Scale Deforestation in Response to Changing Fire Regimes and Altered Post-Fire Vegetation Dynamics

Science.gov (United States)

Tepley, A. J.; Veblen, T. T.; Perry, G.; Anderson-Teixeira, K. J.

2015-12-01

In the face of on-going climatic warming and land-use change, there is growing concern that temperate forest landscapes could be near a tipping point where relatively small changes to the fire regime or altered post-fire vegetation dynamics could lead to extensive conversion to shrublands or savannas. To evaluate vulnerability and resilience to such conversion, we develop a simple model based on three factors we hypothesize to be key in predicting temperate forest responses to changing fire regimes: (1) the hazard rate (i.e., the probability of burning in the next year given the time since the last fire) in closed-canopy forests, (2) the hazard rate for recently-burned, open-canopy vegetation, and (3) the time to redevelop canopy closure following fire. We generate a response surface representing the proportions of the landscape potentially supporting closed-canopy forest and non-forest vegetation under nearly all combinations of these three factors. We then place real landscapes on this response surface to assess the type and magnitude of changes to the fire regime that would drive extensive forest loss. We show that the deforestation of much of New Zealand that followed initial human colonization and the introduction of a new ignition source ca. 750 years ago was essentially inevitable due to the slow rate of forest recovery after fire and the high flammability of post-fire vegetation. In North America's Pacific Northwest, by contrast, a predominantly forested landscape persisted despite two periods of widespread burning in the recent past due in large part to faster post-fire forest recovery and less pronounced differences in flammability between forests and the post-fire vegetation. We also assess the factors that could drive extensive deforestation in other regions to identify where management could reduce this potential and to guide field and modeling work to better understand the responses and ecological feedbacks to changing fire regimes.

Growth and Yield Responses of Vegetable Cowpea ( Vigna ...

African Journals Online (AJOL)

The amendment of acidic soil with lime application enhances nutrient availability for optimum vegetable cowpea production. Field experiments were conducted in the teaching and research farm of Michael Okpara University of Agriculture, Umudike during 2006 and 2007 cropping seasons to determine the growth and yield ...

Combining Silviculture and Landscape Architecture to Enhance the Roadside View

Science.gov (United States)

Philip M. McDonald; R. Burton Litton Jr.

1998-01-01

On a high-quality site in the mixed conifer forest of northern California, understory and overstory vegetation along a 3-mile paved county road were manipulated to enhance the view for the traveler. Traditional silvicultural cutting methods and landscape architectural techniques were blended to give contrast and variability to the vegetation along both sides of the...

Impacts of cwd on understory biodiversity in forest ecosystems in the qinling mountains, china

International Nuclear Information System (INIS)

Yuan, J.; Wei, X.; Shang, Z.; Cheng, F.; Hu, Z.; Zheng, X.; Zhang, S.

2015-01-01

The stocks and characteristics of coarse woody debris (CWD) are expected to reflect forest stand features. However, despite their importance, there have been no reports of CWD stocks and characteristics in the Qinling Mountains. We measured the CWD stocks in different CWD types, decay classes and diameter classes of the five forest types in the Qinling Mountains. The highest biomass of CWD was the Pinus tabulaeformis forest (12.57 t-hm /sup -2/), occupied 5.66 percentage in the biomass of this forest, the lowest occupied 1.03 percentage in Betula albo-sinensis forest (1.82 t-hm /sup -2/). Our results revealed that there was a strong correlation between CWD and forest biomass. When the CWD biomass were 9.9 t-hm /sup -2/ and 11.6 hm /sup -2/, the biomass of Pinus armandi forest and P. tabulaeformis forest reached maximum, respectively. CWD is particularly important for biodiversity, but the importance of CWD in the control of diversity in forest systems has not been fully appreciated and certainly has not been evaluated intensively within China, especially in Qinling forests. In our research, we used species richness (S), Shannon-Wiener index (H), Simpson index (D) and Pielou evenness index (J) to assess the diversity of plant community. According to our analysis, we found 1) the effect of CWD biomass on these a diversity index was dependent on tree, shrub and herb in the five forest types, 2) the impacts of CWD biomass on understory biodiversity were more obvious, 3) With the increase of CWD biomass, the species richness (S), Shannon-Wiener index (H) and Simpson index (D) of understory increased significantly. Our results suggested that there was a relatively lower CWD biomass in the Qinling Mountains, but it had significant effects on forest biomass and diversity of plant community. Reserving CWD was important for eco-forestry, but how many and how characteristic of CWD should be retained need further research. Development of CWD reasonable strategies was

Vegetation response to climate change : implications for Canada's conservation lands

International Nuclear Information System (INIS)

Scott, D.; Lemieux, C.

2003-01-01

Studies have shown that Canada's national parks are vulnerable to the impacts of climate change. A wide range of biophysical climate change impacts could affect the integrity of conservation lands in each region of Canada. This report examines the potential impact of climate change on landscape alterations and vegetation distribution in Canada's wide network of conservation lands. It also presents several ways to integrate climate change into existing conservation policy and adaptation strategies. Canada's conservation lands include provincial parks, migratory bird sanctuaries, national wildlife areas and wildlife protected areas. This is the first study to examine biome changes by applying an equilibrium Global Vegetation Model (GVM) to Canada's network of national park systems. Some of the policy and planning challenges posed by changes in landscape level vegetation were also addressed. The report indicates that in terms of potential changes to the biome classification of Canada's national forests, more northern biomes are projected to decrease. These northern biomes include the tundra, taiga and boreal conifer forests. 56 refs., 8 tabs., 6 figs

Waste vegetable oil survey report

Energy Technology Data Exchange (ETDEWEB)

MacLeod, R. [Science enterprise Algoma seA, Sault Ste. Marie, ON (Canada)

2009-02-06

This study was conducted to estimate potential sources of feedstock waste oils for biodiesel production in the Sault Ste. Marie region of Ontario. Two feedstocks were investigated over a period of several months, notably cooking oil and waste vegetable oil. The study was conducted to examine oil throughput, collection practices, and to gauge interest in local initiatives. A distribution list of commercial restaurant listings was developed, and surveys were conducted with members of private enterprises, city government, and non-profit stakeholders in the region. Average volumes of waste vegetable oil were presented for different types of restaurants. The various types of oil used in the restaurants were also quantified. Results of the study showed a positive public response to the idea of a local biodiesel initiative. Steak house, fast food, and Italian establishments generated the largest portion of waste vegetable oil amongst survey respondents. However, the highest response rates came from establishments with little or no oil consumption. Many franchise fast food restaurants are already in contracts with waste oil removal companies. 3 tabs., 3 figs.

Predicting gender differences in liking for vegetables and preference for a variety of vegetables among 11-year-old children.

Science.gov (United States)

Lehto, Elviira; Ray, Carola; Haukkala, Ari; Yngve, Agneta; Thorsdottir, Inga; Roos, Eva

2015-12-01

We studied the factors that predict liking for vegetables and preference for a variety of vegetables among schoolchildren. Additionally, we examined if there were gender differences in the predictors that explain the hypothesized higher scores in liking vegetables and preferences among girls. The data from the PRO GREENS project included 424 Finnish children (response rate 77%) aged 11 to 12. The children completed validated measures about social and environmental factors related to their liking for vegetables and preferences both at baseline 2009 and follow-up 2010. The associations were examined with regression and mediation analyses. The strongest predictors of both girls' and boys' liking and preferences were higher levels of eating vegetables together with the family, previous vegetable intake and a lower level of perceived barriers. Liking was additionally predicted by a lower level of parental demand that their child should eat vegetables. Girls reported higher levels of liking and preferences in the follow-up. This gender difference was mainly explained by girls' lower level of perceived barriers related to vegetable intake and girls' higher previous vegetable intake. Interventions that aim to increase the low vegetable intake among boys by increasing their liking for vegetables and preference for a variety of vegetables could benefit from targeting perceived barriers, namely boys' perception and values concerning the consumption of vegetables. Copyright © 2015 Elsevier Ltd. All rights reserved.

Canopy arthropod responses to experimental canopy opening and debris deposition in a tropical rainforest subject to hurricanes

Science.gov (United States)

Timothy D. Schowalter; Michael R. Willig; Steven J. Presley

2014-01-01

We analyzed responses of canopy arthropods on seven representative early and late successional overstory and understory tree species to a canopy trimming experiment designed to separate effects of canopy opening and debris pulse (resulting from hurricane disturbance) in a tropical rainforest ecosystem at the Luquillo Experimental Forest Long-Term Ecological Research (...

Vegetation response to the "African Humid Period" termination in Central Cameroon (7° N – new pollen insight from Lake Mbalang

Directory of Open Access Journals (Sweden)

M. Servant

2010-05-01

Full Text Available A new pollen sequence from the Lake Mbalang (7°19´ N, 13°44´ E, 1110 m a.s.l. located on the eastern Adamawa plateau, in Central Cameroon, is presented in this paper to analyze the Holocene African Humid Period (AHP termination and related vegetation changes at 7° N in tropical Africa, completing an important transect for exploring shifts in the northern margin of the African Monsoon. This sequence, spanning the last 7000 cal yr BP, shows that the vegetation response to this transitional climatic period was marked by significant successional changes within the broad context of long-term aridification. Semi-deciduous/sub-montane forest retreat in this area is initially registered as early as ca. 6100 cal yr BP and modern savannah was definitely established at ca. 3000 cal yr BP and stabilized at ca. 2400 cal yr BP; but a slight forest regeneration episode is observed between ca. 5200 and ca. 4200 cal yr BP. In this area with modern high rainfall, increasing in the length of the dry season during the AHP termination linked to a contraction of the northern margin of the Intertropical Convergence Zone (ITCZ from ca. 6100 cal yr BP onward, probably associated with decreasing in cloud cover and/or fog frequency, has primarily controlled vegetation dynamics and above all the disappearance of the forested environment on the Adamawa plateau. Compared to previous studies undertaken in northern tropical and Central Africa, this work clearly shows that the response of vegetation to transitional periods between climatic extremes such as the AHP termination might be different in timing, mode and amplitude according to the regional climate of the study sites, but also according to the stability of vegetation before and during these climatic transitions.

Avian responses to an extreme ice storm are determined by a combination of functional traits, behavioural adaptations and habitat modifications.

Science.gov (United States)

Zhang, Qiang; Hong, Yongmi; Zou, Fasheng; Zhang, Min; Lee, Tien Ming; Song, Xiangjin; Rao, Jiteng

2016-03-01

The extent to which species' traits, behavior and habitat synergistically determine their response to extreme weather events (EWE) remains poorly understood. By quantifying bird and vegetation assemblages before and after the 2008 ice storm in China, combined with interspecific interactions and foraging behaviours, we disentangled whether storm influences avian reassembly directly via functional traits (i.e. behavioral adaptations), or indirectly via habitat variations. We found that overall species richness decreased, with 20 species detected exclusively before the storm, and eight species detected exclusively after. These shifts in bird relative abundance were linked to habitat preferences, dietary guild and flocking behaviours. For instance, forest specialists at higher trophic levels (e.g. understory-insectivores, woodpeckers and kingfishers) were especially vulnerable, whereas open-habitat generalists (e.g. bulbuls) were set to benefit from potential habitat homogenization. Alongside population fluctuations, we found that community reassembly can be rapidly adjusted via foraging plasticity (i.e. increased flocking propensity and reduced perching height). And changes in preferred habitat corresponded to a variation in bird assemblages and traits, as represented by intact canopy cover and high density of large trees. Accurate predictions of community responses to EWE are crucial to understanding ecosystem disturbances, thus linking species-oriented traits to a coherent analytical framework.

Ecosystem response to removal of exotic riparian shrubs and a transition to upland vegetation

Science.gov (United States)

Reynolds, Lindsay V.; Cooper, David J.

2011-01-01

Understanding plant community change over time is essential for managing important ecosystems such as riparian areas. This study analyzed historic vegetation using soil seed banks and the effects of riparian shrub removal treatments and channel incision on ecosystem and plant community dynamics in Canyon de Chelly National Monument, Arizona. We focused on how seeds, nutrients, and ground water influence the floristic composition of post-treatment vegetation and addressed three questions: (1) How does pre-treatment soil seed bank composition reflect post-treatment vegetation composition? (2) How does shrub removal affect post-treatment riparian vegetation composition, seed rain inputs, and ground water dynamics? and (3) Is available soil nitrogen increased near dead Russian olive plants following removal and does this influence post-treatment vegetation? We analyzed seed bank composition across the study area, analyzed differences in vegetation, ground water levels, and seed rain between control, cut-stump and whole-plant removal areas, and compared soil nitrogen and vegetation near removed Russian olive to areas lacking Russian olive. The soil seed bank contained more riparian plants, more native and fewer exotic plants than the extant vegetation. Both shrub removal methods decreased exotic plant cover, decreased tamarisk and Russian olive seed inputs, and increased native plant cover after 2 years. Neither method increased ground water levels. Soil near dead Russian olive trees indicated a short-term increase in soil nitrogen following plant removal but did not influence vegetation composition compared to areas without Russian olive. Following tamarisk and Russian olive removal, our study sites were colonized by upland plant species. Many western North American rivers have tamarisk and Russian olive on floodplains abandoned by channel incision, river regulation or both. Our results are widely applicable to sites where drying has occurred and vegetation

Radiocesium cycling in vegetation and soil

International Nuclear Information System (INIS)

Dahlman, R.C.; Francis, C.W.; Tamura, T.

1975-01-01

Data on cesium dynamics in vegetation and soils are reviewed. Special emphasis is placed on typical environments in the southeastern United States. Clay minerals of soil, especially micaceous types, effectively fix cesium and remove it from biotic components of ecosystems. Fallout 137 Cs enters food chains principally by direct deposition on vegetation; uptake by the root pathway is usually less than direct contamination of plant foliage. Cesium-137 levels in vegetation of the southeastern U. S. Coastal Plain are estimated on the basis of direct deposition from the atmosphere and root uptake from soil. Estimated concentrations, based on current concepts of 137 Cs dynamics in vegetation and fixation in soil, are in good agreement with observed values of 137 Cs in vegetation collected in 1969 and 1970. Mechanisms of direct deposition and of increased uptake by roots due to the absence of micaceous clays adequately explain the higher levels of 137 Cs in vegetation of the Coastal Plain and thus are responsible for the elevated 137 Cs reported for milk of the Tampa, Fla., milkshed

Response of shortgrass Plains vegetation to chronic and seasonally administered gamma radiation

Energy Technology Data Exchange (ETDEWEB)

Fraley, Jr., Leslie [Colorado State Univ., Fort Collins, CO (United States)

1971-08-01

In order to determine the effect of radiation on the structure of native shortgrass plains vegetation, an 8750 Ci 137Cs source was installed on the Central Plains Experimental Range near Nunn, Colorado; The experimental area was divided into 6 treatment sectors, a control, 2 sectors for chronic exposure (irradiation initiated April 1969 and continuing as of August 1971), and one each for spring, summer and late fall seasonal semi-acute (30 day), exposures which were administered during April, July and December, 1969, respectively. Community structure was measured by coefficient of community and diversity index. Yield was determined by clipping plots in September 1970 and visual estimates in September 1969 and 1970 for the grass-sedge component of the vegetation. Individual species sensitivity was determined by density data recorded in April, June and September of 1969 and 1970 and by a phenological index recorded at weekly intervals during the 1969 and 1970 growing seasons. The response of the vegetation was similar whether determined by coefficient of community or diversity with diversity being a more sensitive measure of effects. In the chronically exposed sectors, the exposure rate which resulted in a 50 per cent reduction in these 2 parameters (CC50 or D50) was still decreasing the second growing season and was approximately 18 R/hr for the CC50 as of June 1970 and 10 R/hr for the D50 as of September 1970. For the seasonally exposed sectors, the late fall period (December, 1969) was the most sensitive, summer (July, 1969) the least sensitive and spring (April, 1969) intermediate with CC50 and D50 values of 195 and 90, 240 and 222, and 120 and 74 R/hr for the spring, summer and late fall exposed sectors, respectively. Yield and density data indicated a rapid revegetation of the spring and summer exposed sectors during 1970 as a result of an influx of invader species such as Salsola kali tenuifolia, Chenopodium leptophyllum and Lepidium densiflorum and the

Long-Term Studies of Prescribed Burning in Loblolly Pine Forests of the Southeastern Coastal Plain

Science.gov (United States)

Thomas A. Waldrop; David H. van Lear; F. Thomas Lloyd; William R. Harms

1987-01-01

Prescribed fire provides many benefits in southern pine A study begun in 1946 provides a unique opportunity stands. to observe long-term changes in understory vegetation, soil properties, and overstory tree growth caused by repeated burning.

Pattern of NDVI-based vegetation greening along an altitudinal gradient in the eastern Himalayas and its response to global warming.

Science.gov (United States)

Li, Haidong; Jiang, Jiang; Chen, Bin; Li, Yingkui; Xu, Yuyue; Shen, Weishou

2016-03-01

The eastern Himalayas, especially the Yarlung Zangbo Grand Canyon Nature Reserve (YNR), is a global hotspot of biodiversity because of a wide variety of climatic conditions and elevations ranging from 500 to > 7000 m above sea level (a.s.l.). The mountain ecosystems at different elevations are vulnerable to climate change; however, there has been little research into the patterns of vegetation greening and their response to global warming. The objective of this paper is to examine the pattern of vegetation greening in different altitudinal zones in the YNR and its relationship with vegetation types and climatic factors. Specifically, the inter-annual change of the normalized difference vegetation index (NDVI) and its variation along altitudinal gradient between 1999 and 2013 was investigated using SPOT-VGT NDVI data and ASTER global digital elevation model (GDEM) data. We found that annual NDVI increased by 17.58% in the YNR from 1999 to 2013, especially in regions dominated by broad-leaved and coniferous forests at lower elevations. The vegetation greening rate decreased significantly as elevation increased, with a threshold elevation of approximately 3000 m. Rising temperature played a dominant role in driving the increase in NDVI, while precipitation has no statistical relationship with changes in NDVI in this region. This study provides useful information to develop an integrated management and conservation plan for climate change adaptation and promote biodiversity conservation in the YNR.

Response of nutrients, minerals, antioxidant leaf pigments, vitamins, polyphenol, flavonoid and antioxidant activity in selected vegetable amaranth under four soil water content.

Science.gov (United States)

Sarker, Umakanta; Oba, Shinya

2018-06-30

Four selected vegetable amaranths were grown under four soil water content to evaluate their response in nutrients, minerals, antioxidant leaf pigments, vitamins, polyphenol, flavonoid and total antioxidant activity (TAC). Vegetable amaranth was significantly affected by variety, soil water content and variety × soil water content interactions for all the traits studied. Increase in water stress, resulted in significant changes in proximate compositions, minerals (macro and micro), leaf pigments, vitamin, total polyphenol content (TPC), and total flavonoid content (TFC) of vegetable amaranth. Accessions VA14 and VA16 performed better for all the traits studied. Correlation study revealed a strong antioxidant scavenging activity of leaf pigments, ascorbic acid, TPC and TFC. Vegetable amaranth can tolerate soil water stress without compromising the high quality of the final product in terms of nutrients and antioxidant profiles. Therefore, it could be a promising alternative crop in semi-arid and dry areas and also during dry seasons. Copyright © 2018. Published by Elsevier Ltd.

Drought, climate change and vegetation response in the succulent karoo, South Africa

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M. T. Hoffman

2009-12-01

Full Text Available For the winter-rainfall region of South Africa, the frequency of drought is predicted to increase over the next 100 years, with dire consequences for the vegetation of this biodiversity hotspot. We analysed historical 20th century rainfall records for six rainfall stations within the succulent karoo biome to determine if the signal of increasing drought frequency is already apparent, and whether mean annual rainfall is decreasing. We found no evidence for a decrease either in mean annual rainfall or in the incidence of drought, as measured by the Standardised Precipitation Index (SPI over the 20th century. Evidence points to a drying trend from 1900–1950 while no significant trend in rainfall and drought was found at most stations from 1951–2000. In a second analysis we synthesised the information concerning the response of adult succulent karoo biome plants and seedlings to extended drought conditions. General findings are that responses to drought differ between species, and that longevity is an important life history trait related to drought survival. Growth form is a poor predictor of drought response across the biome. There was a range of responses to drought among adult plants of various growth forms, and among non-succulent seedlings. Leaf-succulent seedlings, however, exhibited phenomenal drought resistance, the majority surviving drought long after all the experimentally comparative non-succulent seedlings had died. Our synthesis showed that previous studies on the impact of drought on succulent karoo biome plants differ greatly in terms of their location, sampling design, measured values and plant responses. A suite of coordinated long-term field observations, experiments and models are therefore needed to assess the response of succulent karoo biome species to key drought events as they occur over time and to integrate this information into conservation planning.

Post Fire Vegetation Recovery in Portugal

Science.gov (United States)

Gouveia, Celia; Bastos, Ana; DaCamara, Carlos; Trigo, Ricardo M.

2011-01-01

Fires in Portugal, as in the Mediterranean ecosystems, have a complex effect on vegetation regeneration due to the different responses of vegetation to the variety of fire regimes and to the complexity of landscape structures. A thorough evaluation of vegetation recovery after fire events becomes therefore crucial in land management. In 2005, Portugal suffered a strong damage from forest fires that damaged an area of 300 000 ha of forest and shrub. This year are particularly interesting because it is associated the severe drought of 2005. The aim of the present study is to identify large burnt scars in Portugal during the 2005 fire seasons and monitoring vegetation behaviour throughout the pre and the post fire periods. The mono-parametric model developed by Gouveia et al. (2010), based on monthly values of NDVI, at the 1km×1km spatial scale, as obtained from the VEGETATION-SPOT5 instrument, from 1999 to 2009, was used.

Potensi Jenis Tumbuhan Bawah Berkhasiat Obat di Hutan Kota Raggawulung, Kabupaten Subang

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Dina Anggraini

2016-03-01

Full Text Available The objective of this research was to know the understory species diversity and to identified the potency of medicinal plants in Ranggawulung Urban Forest. The method of this research is vegetation analysis using circular plot (4 m in diameter, we used 30 plot in the site. We counted number of individuals and species richness. Importance Value Index, Simpson’s, and Shanon-Wiener Index was calculated to describe it’s diversity. The result showed Ranggawulung Urban Forest had high of understory diversity (Shanon-Wiener Index 3,36.  There was 56 understory species, and 19 of them was identified as medicinal plants. There are Ageratum conyzoides, Piper aduncum, Sida rhombifoli, Eupatorium odoratum, and Turnera ulmifolia. The utilization of this potency and the effort to conserve both ex-situ and insitu are also elaborated.

Monitoring Soil Erosion of a Burn Site in the Central Basin and Range Ecoregion: Final Report on Measurements at the Gleason Fire Site, Nevada

Energy Technology Data Exchange (ETDEWEB)

Miller, Julianne [DRI; Etyemezian, Vicken [DRI; Shillito, Rose [DRI; Cablk, Mary [DRI; Fenstermaker, Lynn [DRI; Shafer, David [DOE Legacy Management

2013-10-01

hydrophobicity (water repellency) was noted on burned understory soils up to 12 months after the fire, as was the presence of ash on the soil surface. Soil deteriorated from a strong, definable pre-fire structure to a weakly cohesive mass (unstructured soil) immediately after the fire. Surface soil structure was evident 34 months after the fire at both burned and unburned sites, but was rare and weaker at burned sites. The amount of runoff and sediment was highly variable, but runoff occurred more frequently at burned interspace sites compared to burned understory and unburned interspace sites up to 34 months after the burn. No discernible pattern was evident on the amount of sediment transported, but the size of sediment from burned understory sites was almost double that of burned and unburned interspace soils after the fire, and decreased over the monitoring period. Curve numbers, a measure of the runoff potential, did not indicate any obvious runoff response to the fire. However, slight seasonal changes in curve numbers and runoff potential and, therefore, post-fire runoff response may be a function of fire impacts as well as the time of year that precipitation occurs. Site (interspace or understory) differences in soil properties and runoff persisted even after the fire. Vegetation data showed the presence of invasive grasses after the fire. Results from analysis of wind and water coupled with the spatial analysis of vegetation suggest that wind erosion may continue to occur due to the additional exposed soil surface (burned understory sites) until vegetation becomes re-established, and runoff may occur more frequently in interspace sites. The potential for fire-related wind erosion and water erosion may persist beyond three years in this system.

Assessing the vegetation condition impacts of the 2011 drought across the U.S. southern Great Plains using the vegetation drought response index (VegDRI)

Science.gov (United States)

Tadesse, Tsegaye; Wardlow, Brian D.; Brown, Jesslyn F.; Svoboda, Mark; Hayes, Michael; Fuchs, Brian; Gutzmer, Denise

2015-01-01

The vegetation drought response index (VegDRI), which combines traditional climate- and satellite-based approaches for assessing vegetation conditions, offers new insights into assessing the impacts of drought from local to regional scales. In 2011, the U.S. southern Great Plains, which includes Texas, Oklahoma, and New Mexico, was plagued by moderate to extreme drought that was intensified by an extended period of record-breaking heat. The 2011 drought presented an ideal case study to evaluate the performance of VegDRI in characterizing developing drought conditions. Assessment of the spatiotemporal drought patterns represented in the VegDRI maps showed that the severity and patterns of the drought across the region corresponded well to the record warm temperatures and much-below-normal precipitation reported by the National Climatic Data Center and the sectoral drought impacts documented by the Drought Impact Reporter (DIR). VegDRI values and maps also showed the evolution of the drought signal before the Las Conchas Fire (the largest fire in New Mexico’s history). Reports in the DIR indicated that the 2011 drought had major adverse impacts on most rangeland and pastures in Texas and Oklahoma, resulting in total direct losses of more than $12 billion associated with crop, livestock, and timber production. These severe impacts on vegetation were depicted by the VegDRI at subcounty, state, and regional levels. This study indicates that the VegDRI maps can be used with traditional drought indicators and other in situ measures to help producers and government officials with various management decisions, such as justifying disaster assistance, assessing fire risk, and identifying locations to move livestock for grazing.

Using forest inventory plot data and satellite imagery from MODIS and Landsat-TM to model spatial distribution patterns of honeysuckle and privet

Science.gov (United States)

Dumitru Salajanu; Dennis M. Jacobs

2009-01-01

Forest inventory and analysis data monitor the presence and extent of certain non-native invasive species. Onforestland, non-native species are considered part of the understory vegetation and can be found near canopyopenings as well as and...

Determining the Role of Hydraulic Redistribution Regimes in the Critical Zone

Science.gov (United States)

Lee, E.; Kumar, P.; Barron-Gafford, G.; Scott, R. L.; Hendryx, S.; Sanchez-Canete, E. P.

2015-12-01

A primary challenge in critical zone science is to understand and predict the interaction between aboveground and belowground ecohydrologic processes. We study the role of hydraulic redistribution (HR) by roots as a mechanism for facilitating aboveground-belowground interactions that drive water and carbon dynamics and the development of emergent spatial patterns of soil moisture and vegetation distribution. By linking field measurements of stem, taproot, and lateral root sap flux, with a shared resource model where the soil is a common reservoir, we examine competitive and facilitative dependencies between the co-occurring plant species. We used trenching as a means of severing any HR connectivity between overstory and understory plants in a subset of plots. We monitored leaf- level transpiration, photosynthesis, sub-canopy ET, NEE, soil evaporation, and soil respiration for trenched and un-trenched (control) trees in a dryland savanna that lacks access to stable soil moisture sources. HR in the trees at the site is detected, but the implications of HR on overstory-understory interactions and resulting spatial patterns and gradients remain untested. During an inter-storm period of the rainy season, we observed hydraulic lift, which may be increasing water availability to understory. Understory grasses may survive inter-storm dry periods by way of facilitative dependency on water resources supplied by overstory trees. On the other hand, immediately after storms we observe hydraulic descent that may be reducing water availability for the understory. Modeling is incorporated to capture the competitive and facilitative interaction between aboveground and belowground as detected in the field. This study provides deep insights for dryland regions, which enables broader generalizations regarding the interaction between groundwater, vegetation roots and aboveground assemblage and their role in whole-ecosystem performance.

Responses of Vegetation Cover to Environmental Change in Large Cities of China

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Kai Jin

2018-01-01

Full Text Available Vegetation cover is crucial for the sustainability of urban ecosystems; however, this cover has been undergoing substantial changes in cities. Based on climate data, city statistical data, nighttime light data and the Normalized Difference Vegetation Index (NDVI dataset, we investigate the spatiotemporal variations of climate factors, urban lands and vegetation cover in 71 large cities of China during 1998–2012, and explore their correlations. A regression model between growing-season NDVI (G-NDVI and urban land proportion (PU is built to quantify the impact of urbanization on vegetation cover change. The results indicate that the spatiotemporal variations of temperature, precipitation, PU and G-NDVI are greatly different among the 71 cities which experienced rapid urbanization. The spatial difference of G-NDVI is closely related to diverse climate conditions, while the inter-annual variations of G-NDVI are less sensitive to climate changes. In addition, there is a negative correlation between G-NDVI trend and PU change, indicating vegetation cover in cities have been negatively impacted by urbanization. For most of the inland cities, the urbanization impacts on vegetation cover in urban areas are more severe than in suburban areas. But the opposite occurs in 17 cities mainly located in the coastal areas which have been undergoing the most rapid urbanization. Overall, the impacts of urbanization on G-NDVI change are estimated to be −0.026 per decade in urban areas and −0.015 per decade in suburban areas during 1998–2012. The long-term developments of cities would persist and continue to impact on the environmental change and sustainability. We use a 15-year window here as a case study, which implies the millennia of human effects on the natural biotas and warns us to manage landscapes and preserve ecological environments properly.

Demand Analysis of Selected Fruits and Vegetables in Oman

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A. Omezzine

1998-01-01

Full Text Available Consumer behavior and prospective changes in demand of food product have a significant impact on production and distribution decisions. Consumer responsiveness to changes in prices, income and other demand determinants is very important to production and market decision-makers. The present study estimates demand responses for selected fruits and vegetables in Oman using consumer aggregated national data. The main objective is to generate information needed for making public as well as private decisions. Results indicate that most fruit and vegetable consumers respond to price, and income changes in the expected manner. Responses are different from one commodity to another depending on its nature and importance in the consumer's diet habits. In a few cases income is not a significant determinant of the demand. Moreover, many fruits and vegetables have shown a relationship of substitution and complementary consistent with Omani diet. These results are useful in farmers and distributers to allow them to adjust their production and marketing services according to the consumer’s response.

Responses of the Carbon Storage and Sequestration Potential of Forest Vegetation to Temperature Increases in Yunnan Province, SW China

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Ruiwu Zhou

2018-04-01

Full Text Available The distribution of forest vegetation and forest carbon sequestration potential are significantly influenced by climate change. In this study, a map of the current distribution of vegetation in Yunnan Province was compiled based on data from remote sensing imagery from the Advanced Land Observing Satellite (ALOS from 2008 to 2011. A classification and regression tree (CART model was used to predict the potential distribution of the main forest vegetation types in Yunnan Province and estimate the changes in carbon storage and carbon sequestration potential (CSP in response to increasing temperature. The results show that the current total forest area in Yunnan Province is 1.86 × 107 ha and that forest covers 48.63% of the area. As the temperature increases, the area of forest distribution first increases and then decreases, and it decreases by 11% when the temperature increases from 1.5 to 2 °C. The mean carbon density of the seven types of forest vegetation in Yunnan Province is 84.69 Mg/ha. The total carbon storage of the current forest vegetation in Yunnan Province is 871.14 TgC, and the CSP is 1100.61 TgC. The largest CSP (1114.82 TgC occurs when the temperature increases by 0.5 °C. Incremental warming of 2 °C will sharply decrease the forest CSP, especially in those regions with mature coniferous forest vegetation. Semi-humid evergreen broad-leaved forests were highly sensitive to temperature changes, and the CSP of these forests will decrease with increasing temperature. Warm-hot coniferous forests have the greatest CSP in all simulation scenarios except the scenario of a 2 °C temperature increase. These results indicate that temperature increases can influence the CSP in Yunnan Province, and the largest impact emerged in the 2 °C increase scenario.

Vegetation response to invasive Tamarix control in southwestern U.S. rivers: a collaborative study including 416 sites.

Science.gov (United States)

González, Eduardo; Sher, Anna A; Anderson, Robert M; Bay, Robin F; Bean, Daniel W; Bissonnete, Gabriel J; Bourgeois, Bérenger; Cooper, David J; Dohrenwend, Kara; Eichhorst, Kim D; El Waer, Hisham; Kennard, Deborah K; Harms-Weissinger, Rebecca; Henry, Annie L; Makarick, Lori J; Ostoja, Steven M; Reynolds, Lindsay V; Robinson, W Wright; Shafroth, Patrick B

2017-09-01

Most studies assessing vegetation response following control of invasive Tamarix trees along southwestern U.S. rivers have been small in scale (e.g., river reach), or at a regional scale but with poor spatial-temporal replication, and most have not included testing the effects of a now widely used biological control. We monitored plant composition following Tamarix control along hydrologic, soil, and climatic gradients in 244 treated and 172 reference sites across six U.S. states. This represents the largest comprehensive assessment to date on the vegetation response to the four most common Tamarix control treatments. Biocontrol by a defoliating beetle (treatment 1) reduced the abundance of Tamarix less than active removal by mechanically using hand and chain-saws (2), heavy machinery (3) or burning (4). Tamarix abundance also decreased with lower temperatures, higher precipitation, and follow-up treatments for Tamarix resprouting. Native cover generally increased over time in active Tamarix removal sites, however, the increases observed were small and was not consistently increased by active revegetation. Overall, native cover was correlated to permanent stream flow, lower grazing pressure, lower soil salinity and temperatures, and higher precipitation. Species diversity also increased where Tamarix was removed. However, Tamarix treatments, especially those generating the highest disturbance (burning and heavy machinery), also often promoted secondary invasions of exotic forbs. The abundance of hydrophytic species was much lower in treated than in reference sites, suggesting that management of southwestern U.S. rivers has focused too much on weed control, overlooking restoration of fluvial processes that provide habitat for hydrophytic and floodplain vegetation. These results can help inform future management of Tamarix-infested rivers to restore hydrogeomorphic processes, increase native biodiversity and reduce abundance of noxious species. © 2017 by the

Computer implemented land cover classification using LANDSAT MSS digital data: A cooperative research project between the National Park Service and NASA. 3: Vegetation and other land cover analysis of Shenandoah National Park

Science.gov (United States)

Cibula, W. G.

1981-01-01

Four LANDSAT frames, each corresponding to one of the four seasons were spectrally classified and processed using NASA-developed computer programs. One data set was selected or two or more data sets were marged to improve surface cover classifications. Selected areas representing each spectral class were chosen and transferred to USGS 1:62,500 topographic maps for field use. Ground truth data were gathered to verify the accuracy of the classifications. Acreages were computed for each of the land cover types. The application of elevational data to seasonal LANDSAT frames resulted in the separation of high elevation meadows (both with and without recently emergent perennial vegetation) as well as areas in oak forests which have an evergreen understory as opposed to other areas which do not.

A review of fire effects on vegetation and soils in the Great Basin region: response and ecological site characteristics

Science.gov (United States)

Miller, Richard F.; Chambers, Jeanne C.; Pyke, David A.; Pierson, Fred B.; Williams, C. Jason

2013-01-01

This review synthesizes the state of knowledge on fire effects on vegetation and soils in semi-arid ecosystems in the Great Basin Region, including the central and northern Great Basin and Range, Columbia River Basin, and the Snake River Plain. We summarize available literature related to: (1) the effects of environmental gradients, ecological site, and vegetation characteristics on resilience to disturbance and resistance to invasive species; (2) the effects of fire on individual plant species and communities, biological soil crusts, seed banks, soil nutrients, and hydrology; and (3) the role of fire severity, fire versus fire surrogate treatments, and post-fire grazing in determining ecosystem response. From this, we identify knowledge gaps and present a framework for predicting plant successional trajectories following wild and prescribed fires and fire surrogate treatments. Possibly the three most important ecological site characteristics that influence a site’s resilience (ability of the ecological site to recover from disturbance) and resistance to invasive species are soil temperature/moisture regimes and the composition and structure of vegetation on the ecological site just prior to the disturbance event.

[Differences of vegetation phenology monitoring by remote sensing based on different spectral vegetation indices.

Science.gov (United States)

Zuo, Lu; Wang, Huan Jiong; Liu, Rong Gao; Liu, Yang; Shang, Rong

2018-02-01

Vegetation phenology is a comprehensive indictor for the responses of terrestrial ecosystem to climatic and environmental changes. Remote sensing spectrum has been widely used in the extraction of vegetation phenology information. However, there are many differences between phenology extracted by remote sensing and site observations, with their physical meaning remaining unclear. We selected one tile of MODIS data in northeastern China (2000-2014) to examine the SOS and EOS differences derived from the normalized difference vegetation index (NDVI) and the simple ratio vegetation index (SR) based on both the red and near-infrared bands. The results showed that there were significant differences between NDVI-phenology and SR-phenology. SOS derived from NDVI averaged 18.9 days earlier than that from SR. EOS derived from NDVI averaged 19.0 days later than from SR. NDVI-phenology had a longer growing season. There were significant differences in the inter-annual variation of phenology from NDVI and SR. More than 20% of the pixel SOS and EOS derived from NDVI and SR showed the opposite temporal trend. These results caused by the seasonal curve characteristics and noise resistance differences of NDVI and SR. The observed data source of NDVI and SR were completely consistent, only the mathematical expressions were different, but phenology results were significantly different. Our results indicated that vegetation phenology monitoring by remote sensing is highly dependent on the mathematical expression of vegetation index. How to establish a reliable method for extracting vegetation phenology by remote sensing needs further research.

Ecological Responses to Five Years of Experimental Nitrogen Application in an Upland Jack-pine Stand

Science.gov (United States)

Melaschenko, N.; Berryman, S.; Straker, J.; Berg, K.; McDonough, A.; Watmough, S. A.

2016-12-01

A five-year experimental study was conducted to evaluate the response of an upland jack-pine (Pinus banksiana) forest to elevated levels of nitrogen (N) deposition in Northern Alberta. N deposition in the region is expected to increase with industrial expansion of oil sands activity, and there is regional interest to set N critical loads for sensitive ecosystems. In this study, N was applied as NH4NO3 above a jack-pine canopy via helicopter, annually for five years (2010-2015) at dosages equivalent to 5, 10, 15, 20 and 25 kg N ha-1 yr-1. Approximately 35% of the applied N was retained in the canopy while 65% reached understory vegetation dominated by lichens and mosses. We measured a significant increase in tissue N concentrations of common ground lichens (Cladonia mitis and C. stellaris) and ground moss (Pleurozium schreberi) as well as epiphytic lichens (Hypogymnia physodes and Evernia mesomorpha). On an annual basis, the applied N was primarily captured in the lichen and moss understory, dominated by C. mitis. In the highest treatments, N concentrations in C. mitis were 1.5-2.5 times greater than pre-treatment values. Peak N concentrations in the ground moss Pleurozium schreberi (1.4%) indicate that a threshold of N saturation was reached by year 3. We observed no changes in community composition of vascular and non-vascular plants, or changes in vascular plant tissue N. Chlorophyll levels in C. mitis increased with N treatment, but there was no indication of toxicity or changes to decomposition and growth. After five years of N application, only Peltigera polydactylon, a ground cyanolichen, appeared to be negatively impacted where the thalli showed necrosis at deposition loads >10kg N ha-1 yr-1. No changes to biomass or N ecosystem processes were observed. Based on these observations, we provide evidence that the first adverse ecological effects of N deposition in jack-pine stands occurred at deposition rates of 10 kg N ha-1 yr-1.

Vegetation Description, Rare Plant Inventory, and Vegetation Monitoring for Craig Mountain, Idaho.

Energy Technology Data Exchange (ETDEWEB)

Mancuso, Michael; Moseley, Robert

1994-12-01

The Craig Mountain Wildlife Mitigation Area was purchased by Bonneville Power Administration (BPA) as partial mitigation for wildlife losses incurred with the inundation of Dworshak Reservoir on the North Fork Clearwater River. Upon completion of the National Environmental Protection Act (NEPA) process, it is proposed that title to mitigation lands will be given to the Idaho Department of Fish and Game (IDFG). Craig Mountain is located at the northern end of the Hells Canyon Ecosystem. It encompasses the plateau and steep canyon slopes extending from the confluence of the Snake and Salmon rivers, northward to near Waha, south of Lewiston, Idaho. The forested summit of Craig Mountain is characterized by gently rolling terrain. The highlands dramatically break into the canyons of the Snake and Salmon rivers at approximately the 4,700 foot contour. The highly dissected canyons are dominated by grassland slopes containing a mosaic of shrubfield, riparian, and woodland habitats. During the 1993 and 1994 field seasons, wildlife, habitat/vegetation, timber, and other resources were systematically inventoried at Craig Mountain to provide Fish and Game managers with information needed to draft an ecologically-based management plan. The results of the habitat/vegetation portion of the inventory are contained in this report. The responsibilities for the Craig Mountain project included: (1) vegetation data collection, and vegetation classification, to help produce a GIS-generated Craig Mountain vegetation map, (2) to determine the distribution and abundance of rare plants populations and make recommendations concerning their management, and (3) to establish a vegetation monitoring program to evaluate the effects of Fish and Game management actions, and to assess progress towards meeting habitat mitigation goals.

Vegetation description, rare plant inventory, and vegetation monitoring for Craig Mountain, Idaho

International Nuclear Information System (INIS)

Mancuso, M.; Moseley, R.

1994-12-01

The Craig Mountain Wildlife Mitigation Area was purchased by Bonneville Power Administration (BPA) as partial mitigation for wildlife losses incurred with the inundation of Dworshak Reservoir on the North Fork Clearwater River. Upon completion of the National Environmental Protection Act (NEPA) process, it is proposed that title to mitigation lands will be given to the Idaho Department of Fish and Game (IDFG). Craig Mountain is located at the northern end of the Hells Canyon Ecosystem. It encompasses the plateau and steep canyon slopes extending from the confluence of the Snake and Salmon rivers, northward to near Waha, south of Lewiston, Idaho. The forested summit of Craig Mountain is characterized by gently rolling terrain. The highlands dramatically break into the canyons of the Snake and Salmon rivers at approximately the 4,700 foot contour. The highly dissected canyons are dominated by grassland slopes containing a mosaic of shrubfield, riparian, and woodland habitats. During the 1993 and 1994 field seasons, wildlife, habitat/vegetation, timber, and other resources were systematically inventoried at Craig Mountain to provide Fish and Game managers with information needed to draft an ecologically-based management plan. The results of the habitat/vegetation portion of the inventory are contained in this report. The responsibilities for the Craig Mountain project included: (1) vegetation data collection, and vegetation classification, to help produce a GIS-generated Craig Mountain vegetation map, (2) to determine the distribution and abundance of rare plants populations and make recommendations concerning their management, and (3) to establish a vegetation monitoring program to evaluate the effects of Fish and Game management actions, and to assess progress towards meeting habitat mitigation goals

Green Infrastructure Increases Biogeochemical Responsiveness, Vegetation Growth and Decreases Runoff in a Semi-Arid City, Tucson, AZ, USA

Science.gov (United States)

Meixner, T.; Papuga, S. A.; Luketich, A. M.; Rockhill, T.; Gallo, E. L.; Anderson, J.; Salgado, L.; Pope, K.; Gupta, N.; Korgaonkar, Y.; Guertin, D. P.

2017-12-01

Green Infrastructure (GI) is often viewed as a mechanism to minimize the effects of urbanization on hydrology, water quality, and other ecosystem services (including the urban heat island). Quantifying the effects of GI requires field measurements of the dimensions of biogeochemical, ecosystem, and hydrologic function that we expect GI to impact. Here we investigated the effect of GI features in Tucson, Arizona which has a low intensity winter precipitation regime and a high intensity summer regime. We focused on understanding the effect of GI on soil hydraulic and biogeochemical properties as well as the effect on vegetation and canopy temperature. Our results demonstrate profound changes in biogeochemical and hydrologic properties and vegetation growth between GI systems and nearby control sites. In terms of hydrologic properties GI soils had increased water holding capacity and hydraulic conductivity. GI soils also have higher total carbon, total nitrogen, and organic matter in general than control soils. Furthermore, we tested the sampled soils (control and GI) for differences in biogeochemical response upon wetting. GI soils had larger respiration responses indicating greater biogeochemical activity overall. Long-term Lidar surveys were used to investigate the differential canopy growth of GI systems versus control sites. The results of this analysis indicate that while a significant amount of time is needed to observe differences in canopy growth GI features due increase tree size and thus likely impact street scale ambient temperatures. Additionally monitoring of transpiration, soil moisture, and canopy temperature demonstrates that GI features increase vegetation growth and transpiration and reduce canopy temperatures. These biogeochemical and ecohydrologic results indicate that GI can increase the biogeochemical processing of soils and increase tree growth and thus reduce urban ambient temperatures.

Impacts of disturbance initiated by road construction in a subtropical cloud forest in the Luquillo Experimental Forest, Puerto Rico

Science.gov (United States)

Lydia P. Olander; F.N Scatena; Whendee L. Silver

1998-01-01

The impacts of road construction and the spread of exotic vegetation, which are common threats to upper elevation tropical forests, were evaluated in the subtropical cloud forests of Puerto Rico. The vegetation, soil and microclimate of 6-month-old road®lls, 35-year-old road®lls and mature forest with and without grass understories were compared. Recent road®lls had...

Response of vegetation NDVI to climatic extremes in the arid region of Central Asia: a case study in Xinjiang, China

Science.gov (United States)

Yao, Junqiang; Chen, Yaning; Zhao, Yong; Mao, Weiyi; Xu, Xinbing; Liu, Yang; Yang, Qing

2018-02-01

Observed data showed the climatic transition from warm-dry to warm-wet in Xinjiang during the past 30 years and will probably affect vegetation dynamics. Here, we analyze the interannual change of vegetation index based on the satellite-derived normalized difference vegetation index (NDVI) with temperature and precipitation extreme over the Xinjiang, using the 8-km NDVI third-generation (NDVI3g) from the Global Inventory Modelling and Mapping Studies (GIMMS) from 1982 to 2010. Few previous studies analyzed the link between climate extremes and vegetation response. From the satellite-based results, annual NDVI significantly increased in the first two decades (1981-1998) and then decreased after 1998. We show that the NDVI decrease over the past decade may conjointly be triggered by the increases of temperature and precipitation extremes. The correlation analyses demonstrated that the trends of NDVI was close to the trend of extreme precipitation; that is, consecutive dry days (CDD) and torrential rainfall days (R24) positively correlated with NDVI during 1998-2010. For the temperature extreme, while the decreases of NDVI correlate positively with warmer mean minimum temperature ( Tnav), it correlates negatively with the number of warmest night days ( Rwn). The results suggest that the climatic extremes have possible negative effects on the ecosystem.

Examining Vegetation of Built Landscapes and Their Relationship to Existing Ecosystems

Directory of Open Access Journals (Sweden)

Margaret Livingston

2004-06-01

Full Text Available An understanding of the various influences of urbanisation on plant communities is critical for planning a sustainable future for the planet. For example, landscape practices and sense of place driven by aesthetic influences often dominate in the design of built landscapes, resulting in strikingly different vegetation communities from that of the surrounding communities. Furthermore, these built landscapes in metropolitan areas often markedly influence an inhabitant's impressions of a region's biotic foundation and sense of place. Inhabitants may not consider or understand the ecological impacts of practices that are typically dominated by contemporary cultural aesthetics. Do these cultural aesthetic drivers result in relatively similar landscapes in terms of appearance, regardless of region? The purpose of this study was to document general trends in landscape structure and composition from two distinct, different regions. Specifically, we addressed the questions: how do these built landscapes deviate from their surrounding natural communities and are these built landscapes from the two regions similar in structure and composition? This paper characterised landscape vegetation patterns of typical residential areas in two cities with relatively diverse climatic regions, Tucson, Arizona and Atlanta, Georgia. Comparisons were done on data for plant diversity, density, life form (tree, shrub, groundcover, and vines and species origin (native versus non-native from sites within typical residential subdivisions throughout the two cities. Results were compared with the composition of local typology in order to determine what differences and similarities existed in relation to native biotic communities. In both cities, residential landscapes converged on savannah-type landscapes, emphasising scattered overstory and minimal understory that were more compositionally diverse than the native biotic communities because of the introduction of non

Negative trade-off between changes in vegetation water use and infiltration recovery after reforesting degraded pasture land in the Nepalese Lesser Himalaya

Science.gov (United States)

Ghimire, C. P.; Bruijnzeel, L. A.; Lubczynski, M. W.; Bonell, M.

2014-12-01

This work investigates the trade-off between increases in vegetation water use and rain water infiltration afforded by soil improvement after reforesting severely degraded grassland in the Lesser Himalaya of central Nepal. The hillslope hydrological functioning (surface and subsurface soil hydraulic conductivities and overland flow generation) and the evapotranspiration (rainfall interception and transpiration) of the following contrasting vegetation types were quantified and examined in detail: (i) a nearly undisturbed, natural broadleaved forest; (ii) a 25-year-old, intensively-used pine plantation; and (iii) a highly degraded pasture. Planting pines increased vegetation water use relative to the pasture and natural forest situation by 355 and 55 mm year-1, respectively. On balance, the limited amount of extra infiltration afforded by the pine plantation relative to the pasture (only 90 mm year-1 due to continued soil degradation associated with regular harvesting of litter and understory vegetation in the plantation) proved insufficient to compensate the higher water use of the pines. As such, observed declines in dry season flows in the study area are thought to mainly reflect the higher water use of the pines although the effect could be moderated by better forest and soil management promoting infiltration. In contrast, a comparison of the water use of the natural forest and degraded pasture suggests that replacing the latter by (mature) broadleaved forest would (ultimately) have a near-neutral effect on dry season flows as the approximate gains in infiltration and evaporative losses were very similar (ca. 300 mm year-1 each). The results of the present study underscore the need for proper forest management for optimum hydrological functioning as well as the importance of protecting the remaining natural forests in the region.

Monitoring responses of Mason Pine to acid rain in China based on remote sensing vegetation index

International Nuclear Information System (INIS)

Jin, Jiaxin; Jiang, Hong; Zhang, Xiuying; Wang, Ying; Hou, Chunliang

2014-01-01

Since the 1970s, acid rain has remained in the public spotlight in both Europe and the United States and recently has emerged as an important problem in other regions such as Southeast Asia. To reveal responses of Masson Pine to acid rain during a long time series in central China, we used the interpolation dataset of acid rain and the Global Inventory Modeling and Mapping Studies (GIMMS) normalized difference vegetation index (NDVI) data to derive the monthly pH and NDVI trajectories based on acidity gradients from 1992 to 2006. Then we analyzed inter-annual and seasonal variation of vegetation growth by improved sinusoidal fitting and regression analysis. In the environment of strong acidity and moderate acidity, the growth of Masson Pine was inhibited during the study period, while the slight acidity promoted growth of Masson Pine to some extent. For the multi-year monthly changing trend of NDVI, late spring to mid autumn, the NDVI showed a decreasing trend, especially in June, while from late autumn to the following spring, the NDVI showed a rising tendency, specifically in December and March

Functional Traits, Flocking Propensity, and Perceived Predation Risk in an Amazonian Understory Bird Community.

Science.gov (United States)

Martínez, Ari E; Gomez, Juan P; Ponciano, José Miguel; Robinson, Scott K

2016-05-01

Within a community, different species might share similar predation risks, and, thus, the ability of species to signal and interpret heterospecific threat information may determine species' associations. We combined observational, experimental, and phylogenetic approaches to determine the extent to which evolutionary history and functional traits determined flocking propensity and perceived predation risk (response to heterospecific alarm calls) in a lowland Amazonian bird community. We predicted that small birds that feed myopically and out in the open would have higher flocking propensities and account for a higher proportion of positive responses to alarms. Using generalized linear models and the incorporation of phylogeny on data from 56 species, our results suggest that phylogenetic relationships alongside body size, foraging height, vegetation density, and response to alarm calls influence flocking propensity. Conversely, phylogenetic relationships did not influence response to heterospecific alarm calls. Among functional traits, however, foraging strategy, foraging density, and flocking propensity partially explained responses to alarm calls. Our results suggest that flocking propensity and perceived predation risk are positively related and that functional ecological traits and evolutionary history may explain certain species' associations.

Using lidar data to analyse sinkhole characteristics relevant for understory vegetation under forest cover-case study of a high karst area in the dinaric mountains.

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Milan Kobal

Full Text Available In this article, we investigate the potential for detection and characterization of sinkholes under dense forest cover by using airborne laser scanning data. Laser pulse returns from the ground provide important data for the estimation of digital elevation model (DEM, which can be used for further processing. The main objectives of this study were to map and determine the geomorphometric characteristics of a large number of sinkholes and to investigate the correlations between geomorphology and vegetation in areas with such characteristics. The selected study area has very low anthropogenic influences and is particularly suitable for studying undisturbed karst sinkholes. The information extracted from this study regarding the shapes and depths of sinkholes show significant directionality for both orientation of sinkholes and their distribution over the area. Furthermore, significant differences in vegetation diversity and composition occur inside and outside the sinkholes, which indicates their presence has important ecological impacts.

Using lidar data to analyse sinkhole characteristics relevant for understory vegetation under forest cover-case study of a high karst area in the dinaric mountains.

Science.gov (United States)

Kobal, Milan; Bertoncelj, Irena; Pirotti, Francesco; Dakskobler, Igor; Kutnar, Lado

2015-01-01

In this article, we investigate the potential for detection and characterization of sinkholes under dense forest cover by using airborne laser scanning data. Laser pulse returns from the ground provide important data for the estimation of digital elevation model (DEM), which can be used for further processing. The main objectives of this study were to map and determine the geomorphometric characteristics of a large number of sinkholes and to investigate the correlations between geomorphology and vegetation in areas with such characteristics. The selected study area has very low anthropogenic influences and is particularly suitable for studying undisturbed karst sinkholes. The information extracted from this study regarding the shapes and depths of sinkholes show significant directionality for both orientation of sinkholes and their distribution over the area. Furthermore, significant differences in vegetation diversity and composition occur inside and outside the sinkholes, which indicates their presence has important ecological impacts.

Using Lidar Data to Analyse Sinkhole Characteristics Relevant for Understory Vegetation under Forest Cover—Case Study of a High Karst Area in the Dinaric Mountains

Science.gov (United States)

Kobal, Milan; Bertoncelj, Irena; Pirotti, Francesco; Dakskobler, Igor; Kutnar, Lado

2015-01-01

In this article, we investigate the potential for detection and characterization of sinkholes under dense forest cover by using airborne laser scanning data. Laser pulse returns from the ground provide important data for the estimation of digital elevation model (DEM), which can be used for further processing. The main objectives of this study were to map and determine the geomorphometric characteristics of a large number of sinkholes and to investigate the correlations between geomorphology and vegetation in areas with such characteristics. The selected study area has very low anthropogenic influences and is particularly suitable for studying undisturbed karst sinkholes. The information extracted from this study regarding the shapes and depths of sinkholes show significant directionality for both orientation of sinkholes and their distribution over the area. Furthermore, significant differences in vegetation diversity and composition occur inside and outside the sinkholes, which indicates their presence has important ecological impacts. PMID:25793871

Response of the mean global vegetation distribution to interannual climate variability

Energy Technology Data Exchange (ETDEWEB)

Notaro, Michael [University of Wisconsin-Madison, Center for Climatic Research, Madison, WI (United States)

2008-06-15

The impact of interannual variability in temperature and precipitation on global terrestrial ecosystems is investigated using a dynamic global vegetation model driven by gridded climate observations for the twentieth century. Contrasting simulations are driven either by repeated mean climatology or raw climate data with interannual variability included. Interannual climate variability reduces net global vegetation cover, particularly over semi-arid regions, and favors the expansion of grass cover at the expense of tree cover, due to differences in growth rates, fire impacts, and interception. The area burnt by global fires is substantially enhanced by interannual precipitation variability. The current position of the central United States' ecotone, with forests to the east and grasslands to the west, is largely attributed to climate variability. Among woody vegetation, climate variability supports expanded deciduous forest growth and diminished evergreen forest growth, due to difference in bioclimatic limits, leaf longevity, interception rates, and rooting depth. These results offer insight into future ecosystem distributions since climate models generally predict an increase in climate variability and extremes. (orig.)

Terrestrial transect study on driving mechanism of vegetation changes

Institute of Scientific and Technical Information of China (English)

2008-01-01

In terms of Chinese climate-vegetation model based on the classification of plant functional types, to- gether with climatic data from 1951 to 1980 and two future climatic scenarios (SRES-A2 and SRES-B2) in China from the highest and the lowest emission scenarios of greenhouse gases, the distribution patterns of vegetation types and their changes along the Northeast China Transect (NECT) and the North-South Transect of Eastern China (NSTEC) were simulated in order to understand the driving mechanisms of vegetation changes under climatic change. The results indicated that the vegetation distribution patterns would change significantly under future climate, and the major factors driving the vegetation changes were water and heat. However, the responses of various vegetation types to the changes in water and heat factors were obviously different. The vegetation changes were more sensi- tive to heat factors than to water factors. Thus, in the future climate warming will significantly affect vegetation distribution patterns.

Neurophysiological and behavioural responses to music therapy in vegetative and minimally conscious states

Directory of Open Access Journals (Sweden)

Julian eO'Kelly

2013-12-01

Full Text Available Assessment of awareness for those with disorders of consciousness (DOC is a challenging undertaking, due to the complex presentation of the population, where misdiagnosis rates remain high. Music therapy may be effective in the assessment and rehabilitation with this population due to effects of musical stimuli on arousal, attention and emotion, irrespective of verbal or motor deficits, however, an evidence base is lacking. To address this, a neurophysiological and behavioural study was undertaken comparing EEG, heart rate variability, respiration and behavioural responses of 20 healthy subjects with 21 individuals in vegetative or minimally conscious states (VS or MCS. Subjects were presented with live preferred music and improvised music entrained to respiration (i.e., music therapy procedures, recordings of disliked music, white noise and silence. ANOVA tests indicated a range of significant responses (p ≤ 0.05 across healthy subjects corresponding to arousal and attention in response to preferred music including concurrent increases in respiration rate with globally enhanced EEG power spectra responses across frequency bandwidths. Whilst physiological responses were heterogeneous across patients, significant post hoc EEG amplitude increases for stimuli associated with preferred music were found for frontal midline theta in 6 VS and 4 MCS subjects, and frontal alpha in 3 VS and 4 MCS subjects (p = 0.05 - 0.0001. Furthermore, behavioural data showed a significantly increased blink rate for preferred music (p = 0.029 across the VS cohort. Two VS cases are presented with concurrent changes (p ≤ 0.05 across measures indicative of discriminatory responses to both music therapy procedures. A MCS case study highlights how more sensitive selective attention may distinguish MCS from VS. Further investigation is warranted to explore the use of music therapy for prognostic indicators, and its potential to support neuroplasticity in rehabilitation

Simulating sub-Milankovitch climate variations associated with vegetation dynamics

Directory of Open Access Journals (Sweden)

E. Tuenter

2007-01-01

Full Text Available Climate variability at sub-Milankovitch periods (between 2 and 15 kyr is studied in a set of transient simulations with a coupled atmosphere/ocean/vegetation model of intermediate complexity (CLIMBER-2. Focus is on the region influenced by the African and Asian summer monsoon. Pronounced variations at periods of about 10 kyr (Asia and Africa and about 5 kyr (Asia are found in the monsoonal runoff in response to the precessional forcing. In the model this is due to the following mechanism. For low summer insolation (precession maximum precipitation is low and desert expands at the expense of grass, while for high insolation (precession minimum precipitation is high and the tree fraction increases also reducing the grass fraction. This induces sub-Milankovitch variations in the grass fraction and associated variations in the water holding capacity of the soil. The runoff does not exhibit sub-Milankovitch variability when vegetation is kept fixed. High-latitude vegetation also exhibits sub-Milankovitch variability under both obliquity and precessional forcing. We thus hypothesize that sub-Milankovitch variability can occur due to the dynamic response of the vegetation. However, this mechanism should be further tested with more sophisticated climate/vegetation models.

Phenological response of vegetation to upstream river flow in the Heihe Rive basin by time series analysis of MODIS data

Directory of Open Access Journals (Sweden)

L. Jia

2011-03-01

Full Text Available Liquid and solid precipitation is abundant in the high elevation, upper reach of the Heihe River basin in northwestern China. The development of modern irrigation schemes in the middle reach of the basin is taking up an increasing share of fresh water resources, endangering the oasis and traditional irrigation systems in the lower reach. In this study, the response of vegetation in the Ejina Oasis in the lower reach of the Heihe River to the water yield of the upper catchment was analyzed by time series analysis of monthly observations of precipitation in the upper and lower catchment, river streamflow downstream of the modern irrigation schemes and satellite observations of vegetation index. Firstly, remotely sensed NDVI data acquired by Terra-MODIS are used to monitor the vegetation dynamic for a seven years period between 2000 and 2006. Due to cloud-contamination, atmospheric influence and different solar and viewing angles, however, the quality and consistence of time series of remotely sensed NDVI data are degraded. A Fourier Transform method – the Harmonic Analysis of Time Series (HANTS algorithm – is used to reconstruct cloud- and noise-free NDVI time series data from the Terra-MODIS NDVI dataset. Modification is made on HANTS by adding additional parameters to deal with large data gaps in yearly time series in combination with a Temporal-Similarity-Statistics (TSS method developed in this study to seek for initial values for the large gap periods. Secondly, the same Fourier Transform method is used to model time series of the vegetation phenology. The reconstructed cloud-free NDVI time series data are used to study the relationship between the water availability (i.e. the local precipitation and upstream water yield and the evolution of vegetation conditions in Ejina Oasis from 2000 to 2006. Anomalies in precipitation, streamflow, and vegetation index are detected by comparing each year with the average year. The results showed that

Long-term understory vegetation dynamics and responses to ungulate exclusion in the dry forest of Mona Island

Science.gov (United States)

J. Rojas-Sandoval; E.J. Melendez-Ackerman; J. Fumero-Caban; M. Garcia-Bermudez; J. Sustache; S. Aragon; M. Morales-Vargas; G. Olivieri; D.S. Fernandez

2016-01-01

Mona Island protects one of the most important remnants of Caribbean dry forests and hosts a high diversity of rare and endangered plant and animal species. Feral ungulates (goats and pigs) were introduced to the island ~500 y ago, and their populations may be threatening the conservation of Mona Island’s native biodiversity. In this study, we used permanent fenced and...

N2 fixing alder (Alnus viridis spp.fruticosa) effects on soil properties across a secondary successional chronosequence in interior Alaska

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Jennifer S. Mitchell; Roger W. Ruess

2009-01-01

Green alder (Alnus viridis ssp. fruticosa) is a dominant understory shrub during secondary successional development of upland forests throughout interior Alaska, where it contributes substantially to the nitrogen (N) economy through atmospheric N2 fixation. Across a replicated 200+ year old vegetation...

Vegetation response to soil salinity and waterlogging in three saltmarsh hydrosequences through macronutrients distribution

Science.gov (United States)

Ferronato, Chiara; Speranza, Maria; Ferroni, Lucia; Buscaroli, Alessandro; Vianello, Gilmo; Vittori Antisari, Livia

2018-01-01

Saltmarshes consist of soil hydrosequences, where the complex interactions between water tide fluctuations, soil physicochemical properties and plant colonization contribute to the triggering of the pedogenetic processes and consequently to the stability of the saltmarsh edges. In this study, the composition and richness of the vegetation cover were investigated along soil transects in three different saltmarshes. With the aim to investigate the response of the vegetation to the soil hydroperiod and its influence on the availability of soil nutrients, plant and soil samples were collected in four representative sites on each saltmarsh transect (hydrosequence). Among the different species of saltmarshes, L. vulgare and S. europaea colonized intertidal areas, where an accumulation of nutrients (Ca, K, P, S and Na) and organic C and total N (OC and TN, respectively) was found. These intertidal areas are the "critical transition zones", which drive the transition between the terrestrial and the aquatic systems along the increase of soil salinity and water saturation. Among the different element cycles analysed in the soil-plant system, the analysis of the Na and S dynamic, through both bioconcentration and translocation indexes, explains the different adaptation mechanisms to different salinity and waterlogging stressors. The limiting of the species areal was generally associated firstly with a decrease in their Na and S bioconcentration factor and, to a lesser extent, with the increase in their Na and S translocation.

Response and Resiliency of Wildlife and Vegetation to Large-Scale Wildfires and Climate Change in the North Cascades

Science.gov (United States)

Bartowitz, K.; Morrison, P.; Romain-Bondi, K.; Smith, C. W.; Warne, L.; McGill, D.

2016-12-01

Changing climatic patterns have affected the western US in a variety of ways: decreases in precipitation and snowpack, earlier spring snowmelt, and increased lightning strikes have created a drier, more fire-prone system, despite variability in these characteristics. Wildfires are a natural phenomenon, but have been suppressed for much of the past century. Effects of this evolving fire regime on native vegetation and wildlife are not well understood. Increased frequency and intensity of fires coupled with subsequent drought and extreme heat may inhibit or alter recovery of native ecosystems. We are currently investigating how a mega-fire has affected presence of western gray squirrels (Sciurus griseus, WGS) in the North Cascades, and the mortality, survival, and recovery of vegetation following these fires and extreme drought. The Methow Valley in WA experienced a record-breaking wildfire in 2014, which disturbed nearly 50% of priority habitat of the North Cascades population of WGS. WGS were studied at the same pre and post-fire plots. WGS were present at over half of the post-burn plots (58%). There was a significant difference in the number of WGS hair samples collected in different levels of remaining vegetation: the most in moderate, few in low, and none in high. Vegetation recovery was assessed through field data, and a chronosequence of satellite images and aerial photography. 75% of the 2014 fire burned non-forested vegetation. Ponderosa pine forests comprised the rest. The forests experienced about 70% initial mortality. Recovery of the forest appears slower than in the shrub-steppe. First year seedling survival was poor due to an extremely hot, dry summer, while second year survival appears higher due to a cool, moist spring and summer. One year after a large, multi-severity fire we found WGS may be more resilient to disturbance such as fires than previously thought. Future studies of WGS will help elucidate long-term response to large-scale fires, and

Consumption of fruit and vegetables and risk of frailty: a dose-response analysis of 3 prospective cohorts of community-dwelling older adults.

Science.gov (United States)

García-Esquinas, Esther; Rahi, Berna; Peres, Karine; Colpo, Marco; Dartigues, Jean-François; Bandinelli, Stefania; Feart, Catherine; Rodríguez-Artalejo, Fernando

2016-07-01

Consuming fruit and vegetables (FVs) may protect against frailty, but to our knowledge no study has yet assessed their prospective dose-response relation. We sought to examine the dose-response association between FV consumption and the risk of frailty in older adults. Data were taken from 3 independent cohorts of community-dwelling older adults: the Seniors-ENRICA (Study on Nutrition and Cardiovascular Risk Factors in Spain) cohort (n = 1872), Three-City (3C) Bordeaux cohort (n = 581), and integrated multidisciplinary approach cohort (n = 473). Baseline food consumption was assessed with a validated computerized diet history (Seniors-ENRICA) or with a food-frequency questionnaire (3C Bordeaux and AMI). In all cohorts, incident frailty was assessed with the use of the Fried criteria. Results across cohorts were pooled with the use of a random-effects model. During a mean 2.5-y follow-up, 300 incident frailty cases occurred. Fully adjusted models showed that the pooled ORs (95% CIs) of incident frailty comparing participants who consumed 1, 2, or ≥3 portions of fruit/d to those with no consumption were, respectively, 0.59 (0.27, 0.90), 0.58 (0.29, 0.86), and 0.48 (0.20, 0.75), with a P-trend of 0.04. The corresponding values for vegetables were 0.69 (0.42, 0.97), 0.56 (0.35, 0.77), and 0.52 (0.13, 0.92), with a P-trend consumption of fruit and risk of exhaustion, low physical activity, and slow walking speed, whereas the consumption of vegetables was associated with a decreased risk of exhaustion and unintentional weight loss. Among community-dwelling older adults, FV consumption was associated with a lower short-term risk of frailty in a dose-response manner, and the strongest association was obtained with 3 portions of fruit/d and 2 portions of vegetables/d. © 2016 American Society for Nutrition.

Vegetation Response to Climate Change in the Southern Part of Qinghai-Tibet Plateau at Basinal Scale

Science.gov (United States)

Liu, X.; Liu, C.; Kang, Q.; Yin, B.

2018-04-01

Global climate change has significantly affected vegetation variation in the third-polar region of the world - the Qinghai-Tibet Plateau. As one of the most important indicators of vegetation variation (growth, coverage and tempo-spatial change), the Normalized Difference Vegetation Index (NDVI) is widely employed to study the response of vegetation to climate change. However, a long-term series analysis cannot be achieved because a single data source is constrained by time sequence. Therefore, a new framework was presented in this paper to extend the product series of monthly NDVI, taking as an example the Yarlung Zangbo River Basin, one of the most important river basins in the Qinghai-Tibet Plateau. NDVI products were acquired from two public sources: Global Inventory Modeling and Mapping Studies (GIMMS) Advanced Very High Resolution Radiometer (AVHRR) and Moderate-Resolution Imaging spectroradiometer (MODIS). After having been extended using the new framework, the new time series of NDVI covers a 384 months period (1982-2013), 84 months longer than previous time series of NDVI product, greatly facilitating NDVI related scientific research. In the new framework, the Gauss Filtering Method was employed to filter out noise in the NDVI product. Next, the standard method was introduced to enhance the comparability of the two data sources, and a pixel-based regression method was used to construct NDVI-extending models with one pixel after another. The extended series of NDVI fit well with original AVHRR-NDVI. With the extended time-series, temporal trends and spatial heterogeneity of NDVI in the study area were studied. Principal influencing factors on NDVI were further determined. The monthly NDVI is highly correlated with air temperature and precipitation in terms of climatic change wherein the spatially averaged NDVI slightly increases in the summer and has increased in temperature and decreased in precipitation in the 32 years period. The spatial heterogeneity of

Varying responses of vegetation activity to climate changes on the Tibetan Plateau grassland.

Science.gov (United States)

Cong, Nan; Shen, Miaogen; Yang, Wei; Yang, Zhiyong; Zhang, Gengxin; Piao, Shilong

2017-08-01

Vegetation activity on the Tibetan Plateau grassland has been substantially enhanced as a result of climate change, as revealed by satellite observations of vegetation greenness (i.e., the normalized difference vegetation index, NDVI). However, little is known about the temporal variations in the relationships between NDVI and temperature and precipitation, and understanding this is essential for predicting how future climate change would affect vegetation activity. Using NDVI data and meteorological records from 1982 to 2011, we found that the inter-annual partial correlation coefficient between growing season (May-September) NDVI and temperature (R NDVI-T ) in a 15-year moving window for alpine meadow showed little change, likely caused by the increasing R NDVI-T in spring (May-June) and autumn (September) and decreasing R NDVI-T in summer (July-August). Growing season R NDVI-T for alpine steppe increased slightly, mainly due to increasing R NDVI-T in spring and autumn. The partial correlation coefficient between growing season NDVI and precipitation (R NDVI-P ) for alpine meadow increased slightly, mainly in spring and summer, and R NDVI-P for alpine steppe increased, mainly in spring. Moreover, R NDVI-T for the growing season was significantly higher in those 15-year windows with more precipitation for alpine steppe. R NDVI-P for the growing season was significantly higher in those 15-year windows with higher temperature, and this tendency was stronger for alpine meadow than for alpine steppe. These results indicate that the impact of warming on vegetation activity of Tibetan Plateau grassland is more positive (or less negative) during periods with more precipitation and that the impact of increasing precipitation is more positive (or less negative) during periods with higher temperature. Such positive effects of the interactions between temperature and precipitation indicate that the projected warmer and wetter future climate will enhance vegetation activity

Vegetation Carbon Storage, Spatial Patterns and Response to Altitude in Lancang River Basin, Southwest China

Directory of Open Access Journals (Sweden)

Long Chen

2016-01-01

Full Text Available Vegetation plays a very important role of carbon (C sinks in the global C cycle. With its complex terrain and diverse vegetation types, the Lancang River Basin (LRB of southwest China has huge C storage capacity. Therefore, understanding the spatial variations and controlling mechanisms of vegetation C storage is important to understand the regional C cycle. In this study, data from a forest inventory and field plots were used to estimate and map vegetation C storage distribution in the LRB, to qualify the quantitative relationships between vegetation C density and altitude at sublot and township scale, and a linear model or polynomial model was used to identify the relationship between C density and altitude at two spatial scales and two statistical scales. The results showed that a total of 300.32 Tg C was stored in the LRB, an important C sink in China. The majority of C storage was contributed by forests, notably oaks. The vegetation C storage exhibited nonlinear variation with latitudinal gradients. Altitude had tremendous influences on spatial patterns of vegetation C storage of three geomorphological types in the LRB. C storage decreased with increasing altitude at both town and sublot scales in the flat river valley (FRV region and the mid-low mountains gorge (MMG region, and first increased then decreased in the alpine gorge (AG region. This revealed that, in southwest China, altitude changes the latitudinal patterns of vegetation C storage; especially in the AG area, C density in the mid-altitude (3100 m area was higher than that of adjacent areas.

Blue Water Trade-Offs With Vegetation in a CO2-Enriched Climate

Science.gov (United States)

Mankin, Justin S.; Seager, Richard; Smerdon, Jason E.; Cook, Benjamin I.; Williams, A. Park; Horton, Radley M.

2018-04-01

Present and future freshwater availability and drought risks are physically tied to the responses of surface vegetation to increasing CO2. A single-model large ensemble identifies the occurrence of colocated warming- and CO2-induced leaf area index increases with summer soil moisture declines. This pattern of "greening" and "drying," which occurs over 42% of global vegetated land area, is largely attributable to changes in the partitioning of precipitation at the land surface away from runoff and toward terrestrial vegetation ecosystems. Changes in runoff and ecosystem partitioning are inversely related, with changes in runoff partitioning being governed by changes in precipitation (mean and extremes) and ecosystem partitioning being governed by ecosystem water use and surface resistance to evapotranspiration (ET). Projections show that warming-influenced and CO2-enriched terrestrial vegetation ecosystems use water that historically would have been partitioned to runoff over 48% of global vegetated land areas, largely in Western North America, the Amazon, and Europe, many of the same regions with colocated greening and drying. These results have implications for how water available for people will change in response to anthropogenic warming and raise important questions about model representations of vegetation water responses to high CO2.

Anthropogenic nitrogen deposition in boreal forests has a minor impact on the global carbon cycle.

Science.gov (United States)

Gundale, Michael J; From, Fredrik; Bach, Lisbet H; Nordin, Annika

2014-01-01

It is proposed that increases in anthropogenic reactive nitrogen (Nr ) deposition may cause temperate and boreal forests to sequester a globally significant quantity of carbon (C); however, long-term data from boreal forests describing how C sequestration responds to realistic levels of chronic Nr deposition are scarce. Using a long-term (14-year) stand-scale (0.1 ha) N addition experiment (three levels: 0, 12.5, and 50 kg N ha(-1)  yr(-1) ) in the boreal zone of northern Sweden, we evaluated how chronic N additions altered N uptake and biomass of understory communities, and whether changes in understory communities explained N uptake and C sequestration by trees. We hypothesized that understory communities (i.e. mosses and shrubs) serve as important sinks for low-level N additions, with the strength of these sinks weakening as chronic N addition rates increase, due to shifts in species composition. We further hypothesized that trees would exhibit nonlinear increases in N acquisition, and subsequent C sequestration as N addition rates increased, due to a weakening understory N sink. Our data showed that understory biomass was reduced by 50% in response to the high N addition treatment, mainly due to reduced moss biomass. A (15) N labeling experiment showed that feather mosses acquired the largest fraction of applied label, with this fraction decreasing as the chronic N addition level increased. Contrary to our hypothesis, the proportion of label taken up by trees was equal (ca. 8%) across all three N addition treatments. The relationship between N addition and C sequestration in all vegetation pools combined was linear, and had a slope of 16 kg C kg(-1)  N. While canopy retention of Nr deposition may cause C sequestration rates to be slightly different than this estimate, our data suggest that a minor quantity of annual anthropogenic CO2 emissions are sequestered into boreal forests as a result of Nr deposition. © 2013 John Wiley & Sons Ltd.

Evidence from Individual Inference for High-Dimensional Coexistence: Long-Term Experiments on Recruitment Response

Science.gov (United States)

Clark, James S.; Soltoff, Benjamin D.; Powell, Amanda S.; Read, Quentin D.

2012-01-01

Background For competing species to coexist, individuals must compete more with others of the same species than with those of other species. Ecologists search for tradeoffs in how species might partition the environment. The negative correlations among competing species that would be indicative of tradeoffs are rarely observed. A recent analysis showed that evidence for partitioning the environment is available when responses are disaggregated to the individual scale, in terms of the covariance structure of responses to environmental variation. That study did not relate that variation to the variables to which individuals were responding. To understand how this pattern of variation is related to niche variables, we analyzed responses to canopy gaps, long viewed as a key variable responsible for species coexistence. Methodology/Principal Findings A longitudinal intervention analysis of individual responses to experimental canopy gaps with 12 yr of pre-treatment and 8 yr post-treatment responses showed that species-level responses are positively correlated – species that grow fast on average in the understory also grow fast on average in response to gap formation. In other words, there is no tradeoff. However, the joint distribution of individual responses to understory and gap showed a negative correlation – species having individuals that respond most to gaps when previously growing slowly also have individuals that respond least to gaps when previously growing rapidly (e.g., Morus rubra), and vice versa (e.g., Quercus prinus). Conclusions/Significance Because competition occurs at the individual scale, not the species scale, aggregated species-level parameters and correlations hide the species-level differences needed for coexistence. By disaggregating models to the scale at which the interaction occurs we show that individual variation provides insight for species differences. PMID:22393349

Evidence from individual inference for high-dimensional coexistence: long-term experiments on recruitment response.

Directory of Open Access Journals (Sweden)

James S Clark

Full Text Available BACKGROUND: For competing species to coexist, individuals must compete more with others of the same species than with those of other species. Ecologists search for tradeoffs in how species might partition the environment. The negative correlations among competing species that would be indicative of tradeoffs are rarely observed. A recent analysis showed that evidence for partitioning the environment is available when responses are disaggregated to the individual scale, in terms of the covariance structure of responses to environmental variation. That study did not relate that variation to the variables to which individuals were responding. To understand how this pattern of variation is related to niche variables, we analyzed responses to canopy gaps, long viewed as a key variable responsible for species coexistence. METHODOLOGY/PRINCIPAL FINDINGS: A longitudinal intervention analysis of individual responses to experimental canopy gaps with 12 yr of pre-treatment and 8 yr post-treatment responses showed that species-level responses are positively correlated--species that grow fast on average in the understory also grow fast on average in response to gap formation. In other words, there is no tradeoff. However, the joint distribution of individual responses to understory and gap showed a negative correlation--species having individuals that respond most to gaps when previously growing slowly also have individuals that respond least to gaps when previously growing rapidly (e.g., Morus rubra, and vice versa (e.g., Quercus prinus. CONCLUSIONS/SIGNIFICANCE: Because competition occurs at the individual scale, not the species scale, aggregated species-level parameters and correlations hide the species-level differences needed for coexistence. By disaggregating models to the scale at which the interaction occurs we show that individual variation provides insight for species differences.

Compositional stability of boreal understorey vegetation after overstorey harvesting across a riparian ecotone

Science.gov (United States)

Rebecca L. MacDonald; Han Y.H. Chen; Samuel F. Bartels; Brian J. Palik; Ellie E. Prepas; Frank Gilliam

2015-01-01

Questions: Understanding factors that contribute to the stability of an ecosystem following harvesting is central to predicting responses of boreal ecosystems to increasing human disturbances.While the response of understorey vegetation to harvesting is well understood for upland sites, little is known about compositional stability of riparian understorey vegetation....

Vegetation dynamic characteristics and its responses to climate change in Jinghe River watershed of Loess Plateau, China

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Chang, F.; Liu, W.; Zhou, H.; Ning, T.; Wang, Y.

2017-12-01

The Jinghe River is a second-order tributary of the Yellow River, and located in the middle-south part of the Loess Plateau. The watershed area is 45421km², with the mean annual precipitation (P) being about 508mm and aridity index 2.09. For a long time, soil and water loss in this watershed is severe, resulting in very fragile ecological environment. The GIMMS-normalized vegetation index NDVI is used to reflect condition of vegetation cover, and P and Penman potential evapotranspiration (ET) to represent climate water and heat conditions. The annual actual ET is estimated as the difference between P and runoff (ignoring the change of watershed water storage during each hydrological year, May to April of the following year). These concepts were introduced to discuss the dynamic characteristics of vegetation cover and its response to climate change. Results showed that the mean annual NDVI value was 0.51, showing a stable increasing trend from 2000 with an annual increasing rate of 8.7×10¯³. This result is consistent with the implementation of the project that converts farmland to forests and grassland and has achieved remarkable success in the Loess Plateau since 1999. It also indicates that the positive impact of human activity has been strengthened under the background of climate change. From 1982 to 2012, the annual actual ET was 464mm, accounting for 93.6% of annual P over the same period. The NDVI value of main growing season (5-9 months) is significantly correlated with annual P and annual humid index (ratio of annual P to annual potential ET). Vegetation water consumption is the main part of land surface ET, and the relationship between annual actual ET and NDVI value over the same period is also significant. The NDVI value, P and potential ET variation varied substantially within the Jinghe River watershed, and their relationships in different regions at an inter-annual scale are different. Currently, we are investigating the influence of the changes in

The symbiotic relationship between dominant canopy trees and soil microbes affects the nitrogen source utilization of co-existing understory trees

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Iwaoka, C.; Hyodo, F.; Taniguchi, T.; Shi, W.; Du, S.; Yamanaka, N.; Tateno, R.

2017-12-01

The symbiotic relationship between dominant canopy trees and soil microbes such as mycorrhiza or nitrogen (N) fixer are important determinants of soil N dynamics of a forest. However, it is not known how and to what extent the symbiotic relationship of dominant canopy trees with soil microbes affect the N source of co-existing trees in forest. We measured the δ15N of surface soils (0-10 cm), leaves, and roots of the dominant canopy trees and common understory trees in an arbuscular mycorrhizal N-fixing black locust (Robinia pseudoacacia) plantation and an ectomycorrhizal oak (Quercus liaotungensis) natural forest in a China dryland. We also analyzed the soil dissolved N content in soil extracts and absorbed by ion exchange resin, and soil ammonia-oxidizer abundance using real-time PCR. The δ15N of soil and leaves were higher in the black locust forest than in the oak forest, although the δ15N of fine roots was similar in the two forests, in co-existing understory trees as well as dominant canopy trees. Accordingly, the δ15N of leaves was similar to or higher than that of fine roots in the black locust forest, whereas it was consistently lower than that of fine roots in the oak forest. In the black locust forest, the soil dissolved organic N and ammonium N contents were less abundant but the nitrate N contents in soils and absorbed by the ion exchange resin and ammonia-oxidizer abundance were greater, due to N fixation or less uptake of organic N from arbuscular mycorrhiza. In contrast, the soil dissolved organic N and ammonium N contents were more abundant in the oak forest, whereas the N content featured very low nitrate, due to ectomycorrhizal ability to access organic N. These results suggest that the main N source is nitrate N in the black locust forest, but dissolved organic N or ammonium N in the oak forest. N fixation or high N loss due to high N availability would cause high δ15N in soil and leaves in black locust forest. On the other hand, low soil N

Simulating vegetation response to climate change in the Blue Mountains with MC2 dynamic global vegetation model

Directory of Open Access Journals (Sweden)

John B. Kim

2018-04-01

Full Text Available Warming temperatures are projected to greatly alter many forests in the Pacific Northwest. MC2 is a dynamic global vegetation model, a climate-aware, process-based, and gridded vegetation model. We calibrated and ran MC2 simulations for the Blue Mountains Ecoregion, Oregon, USA, at 30 arc-second spatial resolution. We calibrated MC2 using the best available spatial datasets from land managers. We ran future simulations using climate projections from four global circulation models (GCM under representative concentration pathway 8.5. Under this scenario, forest productivity is projected to increase as the growing season lengthens, and fire occurrence is projected to increase steeply throughout the century, with burned area peaking early- to mid-century. Subalpine forests are projected to disappear, and the coniferous forests to contract by 32.8%. Large portions of the dry and mesic forests are projected to convert to woodlands, unless precipitation were to increase. Low levels of change are projected for the Umatilla National Forest consistently across the four GCM’s. For the Wallowa-Whitman and the Malheur National Forest, forest conversions are projected to vary more across the four GCM-based simulations, reflecting high levels of uncertainty arising from climate. For simulations based on three of the four GCMs, sharply increased fire activity results in decreases in forest carbon stocks by the mid-century, and the fire activity catalyzes widespread biome shift across the study area. We document the full cycle of a structured approach to calibrating and running MC2 for transparency and to serve as a template for applications of MC2. Keywords: Climate change, Regional change, Simulation, Calibration, Forests, Fire, Dynamic global vegetation model

The Impact of CO2-Driven Vegetation Changes on Wildfire Risk

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Skinner, C. B.; Poulsen, C. J.

2017-12-01

While wildfires are a key component of natural ecological restoration and succession, they also pose tremendous risks to human life, health, and property. Wildfire frequency is expected to increase in many regions as the radiative effects of elevated CO2 drive warmer surface air temperatures, earlier spring snow melt, and more frequent meteorological drought. However, high CO2 concentrations will also directly impact vegetation growth and physiology, potentially altering wildfire characteristics through changes in fuel amount and surface hydrology. Depending on the biome and time of year, these vegetation-driven responses may mitigate or enhance radiative-driven wildfire changes. In this study, we use a suite of earth system models from the Coupled Model Intercomparison Project 5 with active biogeophysics and biogeochemistry to understand how the vegetation response to high CO2 (CO2 quadrupling) contributes to future changes in wildfire risk across the globe. Across the models, projected CO2 fertilization enhances aboveground biomass (about a 30% leaf area index (LAI) increase averaged across the globe) during the spring and summer months, increasing the availability of wildfire fuel across all biomes. Despite greater LAI, models robustly project widespread reductions in summer season transpiration (about -15% averaged across the globe) in response to reduced stomatal conductance from CO2 physiological forcing. Reduced transpiration warms summer season near surface temperatures and lowers relative humidity across vegetated regions of the mid-to-high latitudes, heightening the risk of wildfire occurrence. However, as transpiration goes down in response to greater plant water use efficiency, a larger fraction of soil water remains in the soil, potentially halting the spread of wildfires in some regions. Given the myriad ways in which the vegetation response to CO2 may alter wildfire risk, and the robustness of the responses across models, an explicit simulation of

Hydrologic responses to restored wildfire regimes revealed by soil moisture-vegetation relationships

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Boisramé, Gabrielle; Thompson, Sally; Stephens, Scott

2018-02-01

Many forested mountain watersheds worldwide evolved with frequent fire, which Twentieth Century fire suppression activities eliminated, resulting in unnaturally dense forests with high water demand. Restoration of pre-suppression forest composition and structure through a variety of management activities could improve forest resilience and water yields. This study explores the potential for "managed wildfire", whereby naturally ignited fires are allowed to burn, to alter the water balance. Interest in this type of managed wildfire is increasing, yet its long-term effects on water balance are uncertain. We use soil moisture as a spatially-distributed hydrologic indicator to assess the influence of vegetation, fire history and landscape position on water availability in the Illilouette Creek Basin in Yosemite National Park. Over 6000 manual surface soil moisture measurements were made over a period of three years, and supplemented with continuous soil moisture measurements over the top 1m of soil in three sites. Random forest and linear mixed effects models showed a dominant effect of vegetation type and history of vegetation change on measured soil moisture. Contemporary and historical vegetation maps were used to upscale the soil moisture observations to the basin and infer soil moisture under fire-suppressed conditions. Little change in basin-averaged soil moisture was inferred due to managed wildfire, but the results indicated that large localized increases in soil moisture had occurred, which could have important impacts on local ecology or downstream flows.

Oak Forest Responses to Episodic-Seasonal-Drought, Chronic Multi-year Precipitation Change and Acute Drought Manipulations in a Region With Deep Soils and High Precipitation

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Hanson, Paul J.; Wullschleger, Stan D.; Todd, Donald E.; Auge, Robert M.; Froberg, Mats; Johnson, Dale W.

2010-05-01

Implications of episodic-seasonal drought (extremely dry late summers), chronic multi-year precipitation manipulations (±33 percent over 12 years) and acute drought (-100 percent over 3 years) were evaluated for the response of vegetation and biogeochemical cycles for an upland-oak forest. The Quercus-Acer forest is located in eastern Tennessee on deep acidic soils with mean annual temperatures of 14.2 °C and abundant precipitation (1352 mm y-1). The multi-year observations and chronic manipulations were conducted from 1993 through 2005 using understory throughfall collection troughs and redistribution gutters and pipes. Acute manipulations of dominant canopy trees (Quercus prinus; Liriodendron tulipifera) were conducted from 2003 through 2005 using full understory tents. Regional and severe late-summer droughts were produced reduced stand water use and photosynthetic carbon gain as expected. Likewise, seedlings and saplings exhibited reduced survival and cumulative growth reductions. Conversely, multi-year chronic increases or decreases in precipitation and associated soil water deficits did not reduce large tree basal area growth for the tree species present. The resilience of canopy trees to chronic-change was the result of a disconnect between carbon allocation to tree growth (an early-season phenomenon) and late-season drought occurrence. Acute precipitation exclusion from the largest canopy trees also produced limited physiological responses and minimal cumulative growth reductions. Lateral root water sources were removed through trenching and could not explain the lack of response to extreme soil drying. Therefore, deep rooting the primary mechanism for large-tree resilience to severe drought. Extensive trench-based assessments of rooting depth suggested that ‘deep' water supplies were being obtained from limited numbers of deep fine roots. Observations of carbon stocks in organic horizons demonstrated accumulation with precipitation reductions and

Impact of Waste Materials and Organic Amendments on Soil Properties and Vegetative Performance

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Steven L. McGeehan

2012-01-01

Full Text Available Waste materials, and materials derived from wastes, possess many characteristics that can improve soil fertility and enhance crop performance. These materials can be particularly useful as amendments to severely degraded soils associated with mining activities. This study evaluated biosolids, composts, log yard wastes, and two organic soil treatments for improved soil fertility and vegetative performance using side-by-side comparisons. Each plot was seeded with a standardized seed mix and evaluated for a series of soil chemical and physical parameters, total vegetation response, species diversity, ecological plant response, and invasion indices. All treatments were successful at improving soil fertility and promoting a self-sustaining vegetative cover. The level of available nitrogen had a strong impact on vegetative coverage, species distribution, and extent of unseeded vegetation. For example, high nitrogen treatments promoted a grass-dominated (low forb plant community with a low content of unseeded vegetation. In contrast, low nitrogen treatments promoted a more balanced plant community with a mixture of grass and forb species and greater susceptibility to unseeded vegetation establishment.

Review article: Vegetative growth, reproduction, browse production ...

African Journals Online (AJOL)

Vegetative growth, reproduction, browse production and response to tree clearing of ... water stress, soil nutrient availability, carbohydrate reserves, plant hormones, ... animal-plant interactions) of woody plants in various savanna ecosystems.

Increasing biological diversity in a dynamic vegetation model and consequences for simulated response to climate change

Science.gov (United States)

Keribin, R. M.; Friend, A. D.; Purves, D.; Smith, M. J.

2013-12-01

Vegetation, from tropical rainforests to the tundra, is the basis of the world food chain but is also a key component of the Earth system, with biophysical and biogeochemical impacts on the global climate, and Dynamic Global Vegetation Models (DGVMs) are an important integrative tool for understanding its responses to climate change. DGVMs up to now have treated only a small number of plant types representing broad divisions in vegetation worldwide (e.g. trees and grasses, broadleaf and needleleaf, deciduousness), but these categories ignore most of the variation that exists between plant species and between individuals within a species. Research in community ecology makes it clear however that these variations can affect large-scale ecosystem properties such as productivity and resilience to environmental changes. The current challenge is for DGVMs to account for fine-grained variations between plants and a few such models are being developed using newly-available plant trait databases such as the TRY database and insights from community ecology such as habitat filtering. Hybrid is an individual-based DGVM, first published in 1993, that models plant physiology in a mechanistic way. We modified Hybrid 8, the latest version of the model which uses surface physics taken from the GISS ModelE GCM, to include a mechanistic gap-model component with individual-based variation in tree wood density. This key plant trait is known to be strongly correlated with a trade-off between growth and mortality in the majority of forests worldwide, which allows for otherwise-similar individuals to have different life-history strategies. We investigate how the inclusion of continuous variation in wood density into the model affects the ecosystem's transient dynamics under climate change.

Potential Arctic tundra vegetation shifts in response to changing temperature, precipitation and permafrost thaw

NARCIS (Netherlands)

Kolk, van der Henk-Jan; Heijmans, M.M.P.D.; Huissteden, van J.; Pullens, J.W.M.; Berendse, F.

2016-01-01

Over the past decades, vegetation and climate have changed significantly in the Arctic. Deciduous shrub cover is often assumed to expand in tundra landscapes, but more frequent abrupt permafrost thaw resulting in formation of thaw ponds could lead to vegetation shifts towards graminoid-dominated

A Monte Carlo/response surface strategy for sensitivity analysis: application to a dynamic model of vegetative plant growth

Science.gov (United States)

Lim, J. T.; Gold, H. J.; Wilkerson, G. G.; Raper, C. D. Jr; Raper CD, J. r. (Principal Investigator)

1989-01-01

We describe the application of a strategy for conducting a sensitivity analysis for a complex dynamic model. The procedure involves preliminary screening of parameter sensitivities by numerical estimation of linear sensitivity coefficients, followed by generation of a response surface based on Monte Carlo simulation. Application is to a physiological model of the vegetative growth of soybean plants. The analysis provides insights as to the relative importance of certain physiological processes in controlling plant growth. Advantages and disadvantages of the strategy are discussed.

Post-fire plant diversity and abundance in pine and eucalypt stands in Portugal : Effects of biogeography, topography, forest type and post-fire management

NARCIS (Netherlands)

Maia, P.; Keizer, J.; Vasques, A.; Abrantes, N.; Roxo, L.; Fernandes, P.; Ferreira, A.; Moreira, F.

2014-01-01

This study concerned the mid-term regeneration of the woody understory vegetation of pure and mixed stands of Pinus pinaster Ait. and Eucalyptus globulus Labill. in northern and central Portugal following wildfires in 2005 and 2006. Pine and eucalypt stands are the most widespread and most

Map of mixed prairie grassland vegetation, Rocky Flats, Colorado

Energy Technology Data Exchange (ETDEWEB)

Clark, S J.V.; Webber, P J; Komarkova, V; Weber, W A

1980-01-01

A color vegetation map at the scale of 1:12,000 of the area surrounding the Rocky Flats, Rockwell International Plant near Boulder, Colorado, provides a permanent record of baseline data which can be used to monitor changes in both vegetation and environment and thus to contribute to future land management and land-use policies. Sixteen mapping units based on species composition were identified, and characterized by two 10-m/sup 2/ vegetation stands each. These were grouped into prairie, pasture, and valley side on the basis of their species composition. Both the mapping units and these major groups were later confirmed by agglomerative clustering analysis of the 32 vegetation stands on the basis of species composition. A modified Bray and Curtis ordination was used to determine the environmental factor complexes controlling the distribution of vegetation at Rocky flats. Recommendations are made for future policies of environmental management and predictions of the response to environmental change of the present vegetation at the Rocky Flats site.

Vegetation anomalies caused by antecedent precipitation in most of the world

Science.gov (United States)

Papagiannopoulou, C.; Miralles, D. G.; Dorigo, W. A.; Verhoest, N. E. C.; Depoorter, M.; Waegeman, W.

2017-07-01

Quantifying environmental controls on vegetation is critical to predict the net effect of climate change on global ecosystems and the subsequent feedback on climate. Following a non-linear Granger causality framework based on a random forest predictive model, we exploit the current wealth of multi-decadal satellite data records to uncover the main drivers of monthly vegetation variability at the global scale. Results indicate that water availability is the most dominant factor driving vegetation globally: about 61% of the vegetated surface was primarily water-limited during 1981-2010. This included semiarid climates but also transitional ecoregions. Intra-annually, temperature controls Northern Hemisphere deciduous forests during the growing season, while antecedent precipitation largely dominates vegetation dynamics during the senescence period. The uncovered dependency of global vegetation on water availability is substantially larger than previously reported. This is owed to the ability of the framework to (1) disentangle the co-linearities between radiation/temperature and precipitation, and (2) quantify non-linear impacts of climate on vegetation. Our results reveal a prolonged effect of precipitation anomalies in dry regions: due to the long memory of soil moisture and the cumulative, non-linear, response of vegetation, water-limited regions show sensitivity to the values of precipitation occurring three months earlier. Meanwhile, the impacts of temperature and radiation anomalies are more immediate and dissipate shortly, pointing to a higher resilience of vegetation to these anomalies. Despite being infrequent by definition, hydro-climatic extremes are responsible for up to 10% of the vegetation variability during the 1981-2010 period in certain areas, particularly in water-limited ecosystems. Our approach is a first step towards a quantitative comparison of the resistance and resilience signature of different ecosystems, and can be used to benchmark Earth

Vegetation response to climate change : implications for Canada's conservation lands

Energy Technology Data Exchange (ETDEWEB)

Scott, D. [Environment Canada, Ottawa, ON (Canada). Adaptation and Impact Research Group; Lemieux, C. [Waterloo Univ., ON (Canada). Dept. of Geography

2003-05-01

Studies have shown that Canada's national parks are vulnerable to the impacts of climate change. A wide range of biophysical climate change impacts could affect the integrity of conservation lands in each region of Canada. This report examines the potential impact of climate change on landscape alterations and vegetation distribution in Canada's wide network of conservation lands. It also presents several ways to integrate climate change into existing conservation policy and adaptation strategies. Canada's conservation lands include provincial parks, migratory bird sanctuaries, national wildlife areas and wildlife protected areas. This is the first study to examine biome changes by applying an equilibrium Global Vegetation Model (GVM) to Canada's network of national park systems. Some of the policy and planning challenges posed by changes in landscape level vegetation were also addressed. The report indicates that in terms of potential changes to the biome classification of Canada's national forests, more northern biomes are projected to decrease. These northern biomes include the tundra, taiga and boreal conifer forests. 56 refs., 8 tabs., 6 figs.

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.

Plant functional diversity affects climate-vegetation interaction

Science.gov (United States)

Groner, Vivienne P.; Raddatz, Thomas; Reick, Christian H.; Claussen, Martin

2018-04-01

We present how variations in plant functional diversity affect climate-vegetation interaction towards the end of the African Humid Period (AHP) in coupled land-atmosphere simulations using the Max Planck Institute Earth system model (MPI-ESM). In experiments with AHP boundary conditions, the extent of the green Sahara varies considerably with changes in plant functional diversity. Differences in vegetation cover extent and plant functional type (PFT) composition translate into significantly different land surface parameters, water cycling, and surface energy budgets. These changes have not only regional consequences but considerably alter large-scale atmospheric circulation patterns and the position of the tropical rain belt. Towards the end of the AHP, simulations with the standard PFT set in MPI-ESM depict a gradual decrease of precipitation and vegetation cover over time, while simulations with modified PFT composition show either a sharp decline of both variables or an even slower retreat. Thus, not the quantitative but the qualitative PFT composition determines climate-vegetation interaction and the climate-vegetation system response to external forcing. The sensitivity of simulated system states to changes in PFT composition raises the question how realistically Earth system models can actually represent climate-vegetation interaction, considering the poor representation of plant diversity in the current generation of land surface models.

RESPONSE OF RIPARIAN VEGETATION IN AUSTRALIA"S LARGEST RIVER BASIN TO INTER AND INTRA-ANNUAL CLIMATE VARIABILITY AND FLOODING AS QUANTIFIED WITH LANDSAT AND MODIS

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M. Broich

2016-06-01

Full Text Available Australia is a continent subject to high rainfall variability, which has major influences on runoff and vegetation dynamics. However, the resulting spatial-temporal pattern of flooding and its influence on riparian vegetation has not been quantified in a spatially explicit way. Here we focused on the floodplains of the entire Murray-Darling Basin (MDB, an area that covers over 1M km2, as a case study. The MDB is the country’s primary agricultural area with scarce water resources subject to competing demands and impacted by climate change and more recently by the Millennium Drought (1999–2009. Riparian vegetation in the MDB floodplain suffered extensive decline providing a dramatic degradation of riparian vegetation. We quantified the spatial-temporal impact of rainfall, temperature and flooding patters on vegetation dynamics at the subcontinental to local scales and across inter to intra-annual time scales based on three decades of Landsat (25k images, Bureau of Meteorology data and one decade of MODIS data. Vegetation response varied in space and time and with vegetation types, densities and location relative to areas frequently flooded. Vegetation degradation trends were observed over riparian forests and woodlands in areas where flooding regimes have changed to less frequent and smaller inundation extents. Conversely, herbaceous vegetation phenology followed primarily a ‘boom’ and ‘bust’ cycle, related to inter-annual rainfall variability. Spatial patters of vegetation degradation changed along the N-S rainfall gradient but flooding regimes and vegetation degradation patterns also varied at finer scale, highlighting the importance of a spatially explicit, internally consistent analysis and setting the stage for investigating further cross-scale relationships. Results are of interest for land and water management decisions. The approach developed here can be applied to other areas globally such as the Nile river basin and

Fire regimes and vegetation responses in two Mediterranean-climate regions

Science.gov (United States)

Montenegro, G.; Ginocchio, R.; Segura, A.; Keely, J.E.; Gomez, M.

2004-01-01

Wildfires resulting from thunderstorms are common in some Mediterranean-climate regions, such as southern California, and have played an important role in the ecology and evolution of the flora. Mediterranean-climate regions are major centers for human population and thus anthropogenic impacts on fire regimes may have important consequences on these plant formations. However, changes in fire regimes may have different impacts on Mediterranean type-ecosystems depending on the capability of plants to respond to such perturbations. Therefore, we compare here fire regimes and vegetation responses of two Mediterranean-climate regions which differ in wildfire regimes and history of human occupation, the central zone of Chile (matorral) and the southern area of California in United States (chaparral). In Chile almost all fires result from anthropogenic activities, whereas lightning fires resulting from thunderstorms are frequent in California. In both regions fires are more frequent in summer, due to high accumulation of dry plant biomass for ignition. Humans have markedly increased fires frequency both in the matorral and chaparral, but extent of burned areas has remained unaltered, probably due to better fire suppression actions and a decline in the built-up of dry plant fuel associated to increased landscape fragmentation with less flammable agricultural and urban developments. As expected, post-fire plant regeneration responses differs between the matorral and chaparral due to differences in the importance of wildfires as a natural evolutionary force in the system. Plants from the chaparral show a broader range of post-fire regeneration responses than the matorral, from basal resprouting, to lignotuber resprouting, and to fire-stimulated germination and flowering with fire-specific clues such as heat shock, chemicals from smoke or charred wood. Plants from the matorral have some resprouting capabilities after fire, but these probably evolved from other environmental

Predicting the effect of fire on large-scale vegetation patterns in North America.

Science.gov (United States)

Donald McKenzie; David L. Peterson; Ernesto. Alvarado

1996-01-01

Changes in fire regimes are expected across North America in response to anticipated global climatic changes. Potential changes in large-scale vegetation patterns are predicted as a result of altered fire frequencies. A new vegetation classification was developed by condensing Kuchler potential natural vegetation types into aggregated types that are relatively...

Quantifying the Impacts of Environmental Factors on Vegetation Dynamics over Climatic and Management Gradients of Central Asia

Directory of Open Access Journals (Sweden)

Olena Dubovyk

2016-07-01

Full Text Available Currently there is a lack of quantitative information regarding the driving factors of vegetation dynamics in post-Soviet Central Asia. Insufficient knowledge also exists concerning vegetation variability across sub-humid to arid climatic gradients as well as vegetation response to different land uses, from natural rangelands to intensively irrigated croplands. In this study, we analyzed the environmental drivers of vegetation dynamics in five Central Asian countries by coupling key vegetation parameter “overall greenness” derived from Moderate Resolution Imaging Spectroradiometer (MODIS Normalized Difference Vegetation Index (NDVI time series data, with its possible factors across various management and climatic gradients. We developed nine generalized least-squares random effect (GLS-RE models to analyze the relative impact of environmental factors on vegetation dynamics. The obtained results quantitatively indicated the extensive control of climatic factors on managed and unmanaged vegetation cover across Central Asia. The most diverse vegetation dynamics response to climatic variables was observed for “intensively managed irrigated croplands”. Almost no differences in response to these variables were detected for managed non-irrigated vegetation and unmanaged (natural vegetation across all countries. Natural vegetation and rainfed non-irrigated crop dynamics were principally associated with temperature and precipitation parameters. Variables related to temperature had the greatest relative effect on irrigated croplands and on vegetation cover within the mountainous zone. Further research should focus on incorporating the socio-economic factors discussed here in a similar analysis.

Snow effects on alpine vegetation in the Qinghai-Tibetan Plateau

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Wang, Kun; Zhang, Li; Qiu, Yubao; Ji, Lei; Tian, Feng; Wang, Cuizhen; Wang, Zhiyong

2013-01-01

Understanding the relationships between snow and vegetation is important for interpretation of the responses of alpine ecosystems to climate changes. The Qinghai-Tibetan Plateau is regarded as an ideal area due to its undisturbed features with low population and relatively high snow cover. We used 500 m Moderate Resolution Imaging Spectroradiometer (MODIS) datasets during 2001–2010 to examine the snow–vegetation relationships, specifically, (1) the influence of snow melting date on vegetation green-up date and (2) the effects of snow cover duration on vegetation greenness. The results showed that the alpine vegetation responded strongly to snow phenology (i.e., snow melting date and snow cover duration) over large areas of the Qinghai-Tibetan Plateau. Snow melting date and vegetation green-up date were significantly correlated (p growth was influenced by different seasonal snow cover durations (SCDs) in different regions. Generally, the December–February and March–May SCDs played a significantly role in vegetation growth, both positively and negatively, depending on different water source regions. Snow's positive impact on vegetation was larger than the negative impact.

Predicting landscape vegetation dynamics using state-and-transition simulation models

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Colin J. Daniel; Leonardo. Frid

2012-01-01

This paper outlines how state-and-transition simulation models (STSMs) can be used to project changes in vegetation over time across a landscape. STSMs are stochastic, empirical simulation models that use an adapted Markov chain approach to predict how vegetation will transition between states over time, typically in response to interactions between succession,...

VEGETATION RESPONSE TO CLIMATE CHANGE IN THE SOUTHERN PART OF QINGHAI-TIBET PLATEAU AT BASINAL SCALE

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X. Liu

2018-04-01

Full Text Available Global climate change has significantly affected vegetation variation in the third-polar region of the world – the Qinghai-Tibet Plateau. As one of the most important indicators of vegetation variation (growth, coverage and tempo-spatial change, the Normalized Difference Vegetation Index (NDVI is widely employed to study the response of vegetation to climate change. However, a long-term series analysis cannot be achieved because a single data source is constrained by time sequence. Therefore, a new framework was presented in this paper to extend the product series of monthly NDVI, taking as an example the Yarlung Zangbo River Basin, one of the most important river basins in the Qinghai-Tibet Plateau. NDVI products were acquired from two public sources: Global Inventory Modeling and Mapping Studies (GIMMS Advanced Very High Resolution Radiometer (AVHRR and Moderate-Resolution Imaging spectroradiometer (MODIS. After having been extended using the new framework, the new time series of NDVI covers a 384 months period (1982–2013, 84 months longer than previous time series of NDVI product, greatly facilitating NDVI related scientific research. In the new framework, the Gauss Filtering Method was employed to filter out noise in the NDVI product. Next, the standard method was introduced to enhance the comparability of the two data sources, and a pixel-based regression method was used to construct NDVI-extending models with one pixel after another. The extended series of NDVI fit well with original AVHRR-NDVI. With the extended time-series, temporal trends and spatial heterogeneity of NDVI in the study area were studied. Principal influencing factors on NDVI were further determined. The monthly NDVI is highly correlated with air temperature and precipitation in terms of climatic change wherein the spatially averaged NDVI slightly increases in the summer and has increased in temperature and decreased in precipitation in the 32 years period. The

Exploiting differential vegetation phenology for satellite-based mapping of semiarid grass vegetation in the southwestern United States and northern Mexico

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Dye, Dennis G.; Middleton, Barry R.; Vogel, John M.; Wu, Zhuoting; Velasco, Miguel G.

2016-01-01

We developed and evaluated a methodology for subpixel discrimination and large-area mapping of the perennial warm-season (C4) grass component of vegetation cover in mixed-composition landscapes of the southwestern United States and northern Mexico. We describe the methodology within a general, conceptual framework that we identify as the differential vegetation phenology (DVP) paradigm. We introduce a DVP index, the Normalized Difference Phenometric Index (NDPI) that provides vegetation type-specific information at the subpixel scale by exploiting differential patterns of vegetation phenology detectable in time-series spectral vegetation index (VI) data from multispectral land imagers. We used modified soil-adjusted vegetation index (MSAVI2) data from Landsat to develop the NDPI, and MSAVI2 data from MODIS to compare its performance relative to one alternate DVP metric (difference of spring average MSAVI2 and summer maximum MSAVI2), and two simple, conventional VI metrics (summer average MSAVI2, summer maximum MSAVI2). The NDPI in a scaled form (NDPIs) performed best in predicting variation in perennial C4 grass cover as estimated from landscape photographs at 92 sites (R2 = 0.76, p landscapes of the Southwest, and potentially for monitoring of its response to drought, climate change, grazing and other factors, including land management. With appropriate adjustments, the method could potentially be used for subpixel discrimination and mapping of grass or other vegetation types in other regions where the vegetation components of the landscape exhibit contrasting seasonal patterns of phenology.

Enhancement of vegetation-rainfall feedbacks on the Australian summer monsoon by the Madden-Julian Oscillation

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Notaro, Michael

2018-01-01

A regional climate modeling analysis of the Australian monsoon system reveals a substantial modulation of vegetation-rainfall feedbacks by the Madden Julian Oscillation (MJO), both of which operate at similar sub-seasonal time scales, as evidence that the intensity of land-atmosphere interactions is sensitive to the background atmospheric state. Based on ensemble experiments with imposed modification of northern Australian leaf area index (LAI), the atmospheric responses to LAI anomalies are composited for negative and positive modes of the propagating MJO. In the regional climate model (RCM), northern Australian vegetation feedbacks are characterized by evapotranspiration (ET)-driven rainfall responses, with the moisture feedback mechanism dominating over albedo and roughness feedback mechanisms. During November-April, both Tropical Rainfall Measuring Mission and RCM data reveal MJO's pronounced influence on rainfall patterns across northern Australia, tropical Indian Ocean, Timor Sea, Arafura Sea, and Gulf of Carpentaria, with the MJO dominating over vegetation feedbacks in terms of regulating monsoon rainfall variability. Convectively-active MJO phases support an enhancement of positive vegetation feedbacks on monsoon rainfall. While the MJO imposes minimal regulation of ET responses to LAI anomalies, the vegetation feedback-induced responses in precipitable water, cloud water, and rainfall are greatly enhanced during convectively-active MJO phases over northern Australia, which are characterized by intense low-level convergence and efficient precipitable water conversion. The sub-seasonal response of vegetation-rainfall feedback intensity to the MJO is complex, with significant enhancement of rainfall responses to LAI anomalies in February during convectively-active MJO phases compared to minimal modulation by the MJO during prior and subsequent calendar months.

Restoration of the Native Plant Communities in Longleaf Pine Landscapes on the Kisatchie National Forest, Louisiana

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James D. Haywood; Alton Martin; Finis L. Harris; Michael L. Elliott-Smith

1998-01-01

In January 1993, the Kisatchie National Forest and Southern Research Station began monitoring the effects of various management practices on overstory and midstory trees, shrubs, and understory woody and herbaceous vegetation in several longleaf pine (Pinus palustris Mill.) stands. The monitoring of these stands is part of several Ecosystem...

Lipid production in aquatic plant Azolla at vegetative and reproductive stages and in response to abiotic stress.

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Miranda, Ana F; Liu, Zhiqian; Rochfort, Simone; Mouradov, Aidyn

2018-03-01

The aquatic plant Azolla became increasingly popular as bioenergy feedstock because of its high growth rate, production of biomass with high levels of biofuel-producing molecules and ability to grow on marginal lands. In this study, we analysed the contribution of all organs of Azolla to the total yield of lipids at vegetative and reproductive stages and in response to stress. Triacylglycerol-containing lipid droplets were detected in all (vegetative and reproductive) organs with the highest level in the male microsporocarps and microspores. As a result, significantly higher total yields of lipids were detected in Azolla filiculoides and Azolla pinnata at the reproductive stage. Starving changed the yield and composition of the fatty acid as a result of re-direction of carbon flow from fatty acid to anthocyanin pathways. The composition of lipids, in regard the length and degree of unsaturation of fatty acids, in Azolla meets most of the important requirements for biodiesel standards. The ability of Azolla to grow on wastewaters, along with their high productivity rate, makes it an attractive feedstock for the production of biofuels. Copyright © 2018 Elsevier Masson SAS. All rights reserved.

Response of soft winter wheat (Triticum aestivum L. to longtime enforced dormancy and time of spring vegetation recommencing

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В. С. Хахула

2013-05-01

Full Text Available The article highlights the results of studying the soft winter wheat response to the duration of enforced winter dormancy and the time of vegetation recommencing, their impact on growth, development and the survival of the crops. It is found that the impact of those factors in the conditions of central Forest-Steppe of Ukraine is essential, which is to be taken into consideration when scheduling the measures of spring and summer care over the cultivated crops, in particular, where the spring extra nutrition takes place, pesticides and growth regulators are applied, the spaced planting resowing or partial resowing issues are to be settled down. The ecological effect of spring vegetation recommencing dates does not expose annually, therefore it is not always possible to predict the plant development type, but it is possible, nevertheless, to influence the processes of growth, development and survival of plants throughout spring-summer period and the development of their production capacity by means of introducing the intense technologies, optimization of mineral nutrition and the use of plant growth regulators, protection from rogues, diseases, pests.

Late Pliocene diversity and distribution of Drynaria (Polypodiaceae in western Yunnan explained by forest vegetation and humid climates

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Yong-Jiang Huang

2016-08-01

Full Text Available The palaeodiversity of flowering plants in Yunnan has been extensively interpreted from both a molecular and fossil perspective. However, for cryptogamic plants such as ferns, the palaeodiversity remains poorly known. In this study, we describe a new ferny fossil taxon, Drynaria lanpingensis sp. nov. Huang, Su et Zhou (Polypodiaceae, from the late Pliocene of northwestern Yunnan based on fragmentary frond and pinna with in situ spores. The frond is pinnatifid and the pinnae are entirely margined. The sori are arranged in one row on each side of the primary vein. The spores have a semicircular to bean-shaped equatorial view and a tuberculate surface. Taken together with previously described fossils, there are now representatives of three known fossil taxa of Drynaria from the late Pliocene of western Yunnan. These finds suggest that Drynaria diversity was considerable in the region at that time. As Drynaria is a shade-tolerant plant, growing preferably in wet conditions in the understory of forests, its extensive existence may indicate forest vegetation and humid climates in western Yunnan during the late Pliocene. This is in line with results from floristic investigations and palaeoclimatic reconstructions based on fossil floras.

Implications of introducing realistic fire response traits in a Dynamic Global Vegetation Model

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Kelley, D.; Harrison, S. P.; Prentice, I. C.

2013-12-01

the next growing season, while regenerating from seed at 10% the rate of non-resprouters. Tests of LPX-Mv1 for Australia - a continent with a wide range of fire-adapted ecosystems - show that it produces a 33% improvement in the simulation of vegetation composition compared to the previous version of the model, with more realistic vegetation transitions from forests to woodland/savanna. It also produces a 19% improvement in the simulation of burnt area compared to the original model. Resprouting PFTs dominate tropical and temperate areas where the climate is semi-humid but are not common in very dry or very wet areas. Comparison with site-based observations of the abundance of resprouters indicate this is realistic. Ecosystems dominated by resprouters in the simulations recover to pre-fire levels of biomass within 5-7 years, much faster than ecosystems dominated by non-resprouters; again this is confirmed by our analyses of the observations. Simulations of the response to projected future climate change show that the incorporation of adaptive bark thickness and of resprouting has a significant effect on terrestrial carbon stocks in fire-affected areas.

Wet season water distribution in a tropical Andean cloud forest of Boyacá (Colombia) during the dry climate of El Niño

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Garcia-Santos, G.; Berdugo, M. B.

2010-07-01

Fog has been demonstrated as the only source of moisture during the dry climate of El Niño in the tropical Andean cloud forest of Boyacá region in Colombia, yet its importance for the forest is virtually unknown. We assessed fog water distribution during the wet season inside the forest and outside in a practically deforested area. Water intercepted by plant was measured at different vertical stratus. Soil moisture in the first centimetres was also measured. During the anomalous drier wet season there was lack of rainfall and the total recorded cloud water was lower compared with the same period during the previous year. Our results indicated that the upper part of the forest mass intercepts most of the fog water compared with lower stratus when the fog event starts. However upper most stratus became rapidly drier after the event, which is explained because water is released to the atmosphere due to high heat atmosphere-leaves interface fluctuations caused by wind and solar radiation, flows towards a different water potential and drips from the leaves. Low amount of fog dripped from tree foliage into the soil, indicating a large water storage capacity of the epiphyte and bryophyte vegetation. Despite the small amount of throughfall, understory vegetation and litter remained wet, which might be explained by the water flowing through the epiphyte vegetation or the high capacity of the understory to absorb moisture from the air. Soil water did not infiltrate in depth, which underlines the importance of fog as water and cool source for seedling growth and shallow rooted understory species, especially during drier conditions.

Short-term responses of decomposers and vegetation to stump removal

Energy Technology Data Exchange (ETDEWEB)

Kataja-aho, S.

2011-07-01

Stump removal has become a common practice to produce raw material for bioenergy production. It was hypothesized that stump removal is an extensive and more intense disturbance for forest ecosystems (soil decomposer organisms and vegetation) compared to traditional site preparation after clear cutting. Therefore, the effects of stump harvesting on forest soil decomposers, vegetation and nutrient dynamics in undisturbed patches of the forest soil and in exposed mineral soil were compared to the effects of the traditional site preparation method, mounding. Nematodes and enchytraeids were the only decomposer groups that were directly affected (negatively) by the stump removal. Regardless of the treatment, the abundances of most of the decomposer groups were consistently lower in the exposed mineral soil than in the intact forest soil. There was 2-3 times more exposed mineral soil in stump removal sites compared to mounding sites. When this was taken into account, the decomposer community was negatively affected by the stump removal at the forest stand level. However, the greater soil disturbance at the stump harvesting sites enhanced CO{sub 2} production, net nitrogen mineralisation and nitrification. The increased N availability and the changes in microclimate due to the disturbance probably explained the vegetation increase at the stump harvested sites. Planted Norway spruce seedlings grew faster during the first two growing periods at the stump removal sites than at the mounding sites. The seedlings had high and similar ectomycorrhizal colonization rate in both treatments. In the short-term, it is probably not the resources removed in the stumps themselves, but the degree and amount of soil disturbance during the stump harvesting procedure that affects the decomposer community and its function in the clear-felled stands. (orig.)

Ecosystem Evapotranspiration as a Response to Climate and Vegetation Coverage Changes in Northwest Yunnan, China.

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Yang, Hao; Luo, Peng; Wang, Jun; Mou, Chengxiang; Mo, Li; Wang, Zhiyuan; Fu, Yao; Lin, Honghui; Yang, Yongping; Bhatta, Laxmi Dutt

2015-01-01

Climate and human-driven changes play an important role in regional droughts. Northwest Yunnan Province is a key region for biodiversity conservation in China, and it has experienced severe droughts since the beginning of this century; however, the extent of the contributions from climate and human-driven changes remains unclear. We calculated the ecosystem evapotranspiration (ET) and water yield (WY) of northwest Yunnan Province, China from 2001 to 2013 using meteorological and remote sensing observation data and a Surface Energy Balance System (SEBS) model. Multivariate regression analyses were used to differentiate the contribution of climate and vegetation coverage to ET. The results showed that the annual average vegetation coverage significantly increased over time with a mean of 0.69 in spite of the precipitation fluctuation. Afforestation/reforestation and other management efforts attributed to vegetation coverage increase in NW Yunnan. Both ET and WY considerably fluctuated with the climate factors, which ranged from 623.29 mm to 893.8 mm and -51.88 mm to 384.40 mm over the time period. Spatially, ET in the southeast of NW Yunnan (mainly in Lijiang) increased significantly, which was in line with the spatial trend of vegetation coverage. Multivariate linear regression analysis indicated that climatic factors accounted for 85.18% of the ET variation, while vegetation coverage explained 14.82%. On the other hand, precipitation accounted for 67.5% of the WY. We conclude that the continuous droughts in northwest Yunnan were primarily climatically driven; however, man-made land cover and vegetation changes also increased the vulnerability of local populations to drought. Because of the high proportion of the water yield consumed for subsistence and poor infrastructure for water management, local populations have been highly vulnerable to climate drought conditions. We suggest that conservation of native vegetation and development of water

Satellite Monitoring of Vegetation Response to Precipitation and Dust Storm Outbreaks in Gobi Desert Regions

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Yuki Sofue

2018-02-01

Full Text Available Recently, droughts have become widespread in the Northern Hemisphere, including in Mongolia. The ground surface condition, particularly vegetation coverage, affects the occurrence of dust storms. The main sources of dust storms in the Asian region are the Taklimakan and Mongolian Gobi desert regions. In these regions, precipitation is one of the most important factors for growth of plants especially in arid and semi-arid land. The purpose of this study is to clarify the relationship between precipitation and vegetation cover dynamics over 29 years in the Gobi region. We compared the patterns between precipitation and Normalized Difference Vegetation Index (NDVI for a period of 29 years. The precipitation and vegetation datasets were examined to investigate the trends during 1985–2013. Cross correlation analysis between the precipitation and the NDVI anomalies was performed. Data analysis showed that the variations of NDVI anomalies in the east region correspond well with the precipitation anomalies during this period. However, in the southwest region of the Gobi region, the NDVI had decreased regardless of the precipitation amount, especially since 2010. This result showed that vegetation in this region was more degraded than in the other areas.

Comparing the response of birds and butterflies to vegetation-based mountain ecotones using boundary detection approaches.

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Kent, Rafi; Levanoni, Oded; Banker, Eran; Pe'er, Guy; Kark, Salit

2013-01-01

Mountains provide an opportunity to examine changes in biodiversity across environmental gradients and areas of transition (ecotones). Mountain ecotones separate vegetation belts. Here, we aimed to examine whether transition areas for birds and butterflies spatially correspond with ecotones between three previously described altitudinal vegetation belts on Mt. Hermon, northern Israel. These include the Mediterranean Maquis, xero-montane open forest and Tragacanthic mountain steppe vegetation belts. We sampled the abundance of bird and butterfly species in 34 sampling locations along an elevational gradient between 500 and 2200 m. We applied wombling, a boundary-detection technique, which detects rapid changes in a continuous variable, in order to locate the transition areas for bird and butterfly communities and compare the location of these areas with the location of vegetation belts as described in earlier studies of Mt. Hermon. We found some correspondence between the areas of transition of both bird and butterfly communities and the ecotones between vegetation belts. For birds and butterflies, important transitions occurred at the lower vegetation ecotone between Mediterranean maquis and the xero-montane open forest vegetation belts, and between the xero-montane open forest and the mountain steppe Tragacanthic belts. While patterns of species turnover with elevation were similar for birds and butterflies, the change in species richness and diversity with elevation differed substantially between the two taxa. Birds and butterflies responded quite similarly to the elevational gradient and to the shift between vegetation belts in terms of species turnover rates. While the mechanisms generating these patterns may differ, the resulting areas of peak turnover in species show correspondence among three different taxa (plants, birds and butterflies).

Modeling Water and Nutrient Transport through the Soil-Root-Canopy Continuum: Explicitly Linking the Below- and Above-Ground Processes

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Kumar, P.; Quijano, J. C.; Drewry, D.

2010-12-01

Vegetation roots provide a fundamental link between the below ground water and nutrient dynamics and above ground canopy processes such as photosynthesis, evapotranspiration and energy balance. The “hydraulic architecture” of roots, consisting of the structural organization of the root system and the flow properties of the conduits (xylem) as well as interfaces with the soil and the above ground canopy, affect stomatal conductance thereby directly linking them to the transpiration. Roots serve as preferential pathways for the movement of moisture from wet to dry soil layers during the night, both from upper soil layer to deeper layers during the wet season (‘hydraulic descent’) and vice-versa (‘hydraulic lift’) as determined by the moisture gradients. The conductivities of transport through the root system are significantly, often orders of magnitude, larger than that of the surrounding soil resulting in movement of soil-moisture at rates that are substantially larger than that through the soil. This phenomenon is called hydraulic redistribution (HR). The ability of the deep-rooted vegetation to “bank” the water through hydraulic descent during wet periods for utilization during dry periods provides them with a competitive advantage. However, during periods of hydraulic lift these deep-rooted trees may facilitate the growth of understory vegetation where the understory scavenges the hydraulically lifted soil water. In other words, understory vegetation with relatively shallow root systems have access to the banked deep-water reservoir. These inter-dependent root systems have a significant influence on water cycle and ecosystem productivity. HR induced available moisture may support rhizosphere microbial and mycorrhizal fungi activities and enable utilization of heterogeneously distributed water and nutrient resources To capture this complex inter-dependent nutrient and water transport through the soil-root-canopy continuum we present modeling

VEGETATION MAPPING IN WETLANDS

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F. PEDROTTI

2004-01-01

Full Text Available The current work examines the main aspects of wetland vegetation mapping, which can be summarized as analysis of the ecological-vegetational (ecotone gradients; vegetation complexes; relationships between vegetation distribution and geomorphology; vegetation of the hydrographic basin lo which the wetland in question belongs; vegetation monitoring with help of four vegetation maps: phytosociological map of the real and potential vegetation, map of vegetation dynamical tendencies, map of vegetation series.

Habitat selection of endemic birds in temperate forests in a biodiversity "Hotspot"

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Roberto A. Moreno-García

2014-08-01

Full Text Available Aim of study: Our objective was to find habitat associations at a microhabitat level for two endemic birds in a Chilean temperate forest (biodiversity “hotspots”, in order to integrate biodiversity into forest planning.Area of study: Nahuelbuta Range, Chile.Material and methods: The two birds studied were Scelorchilus rubecula (Chucao Tapaculo and Scytalopus magellanicus (Magellanic Tapaculo, both belonging to the Rhinocryptidae family. Presence or absence of the two species was sampled in 57 census spots. Habitat was categorized according to presence/absence results. We assessed the influence of abiotic variables (altitude, exposure, slope and vegetation structure (percentage of understory cover, number of strata using a statistical cluster analysis.Main results: The two bird species selected the habitat. Most frequent presence was detected at a range of 600-1100 masl, but Magellanic Tapaculo was associated to more protected sites in terms of vegetation structure (50-75% for understory cover and 2-3 strata. Slope was the most relevant abiotic variable in habitat selection due to its linkage to vegetation traits in this area.Research highlights: Our results can help managers to integrate biodiversity (endemic fauna species into forest planning by preserving certain traits of the vegetation as part of a habitat (at a microhabitat level selected by the fauna species. That planning should be implemented with both an adequate wood harvesting cuts system and specific silvicultural treatments.Key words: Chile; Nahuelbuta; rhinocryptidae; cluster analysis; rorest planning; vegetation structure.

Canopy Modeling of Aquatic Vegetation: Construction of Submerged Vegetation Index

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Ma, Z.; Zhou, G.

2018-04-01

The unique spectral characteristics of submerged vegetation in wetlands determine that the conventional terrestrial vegetation index cannot be directly employed to species identification and parameter inversion of submerged vegetation. Based on the Aquatic Vegetation Radiative Transfer model (AVRT), this paper attempts to construct an index suitable for submerged vegetation, the model simulated data and a scene of Sentinel-2A image in Taihu Lake, China are utilized for assessing the performance of the newly constructed indices and the existent vegetation indices. The results show that the angle index composed by 525 nm, 555 nm and 670 nm can resist the effects of water columns and is more sensitive to vegetation parameters such as LAI. Furthermore, it makes a well discrimination between submerged vegetation and water bodies in the satellite data. We hope that the new index will provide a theoretical basis for future research.

Radiation preservation and test marketing of fruits and vegetables

International Nuclear Information System (INIS)

Xu Zhicheng; Cai Dong; He Fuying; Zhao Deyao

1993-01-01

To develop the technology for radiation preservation of fruits and vegetables, many varieties of fruits and vegetables had been researched. Results showed that low dose irradiation is useful to preserve fruits and vegetables. On the basis of research, 1900 tons of garlic, 950 tons onion, 500 tons potatoes, 710 tons apples and 1000 kg litchi had been irradiated on a commercial scale. The quality control standards of irradiated garlic, onion and potato had been established and used for commercial scale irradiation. In order to collect consumers in-store response to irradiated foods, a special counter was set up for selling irradiated apples in Nan Jing Road (W), Shanghai. 634 sheets of consumer in-store response investigation forms have been returned and analysed. These results showed that when consumer understands the benefit of irradiation preservation such as higher quality, greater safety, longer shelf-life, wide product availability, or good prices for value, consumer would willingly buy irradiated food. (author)

Abrupt vegetation transitions characterise long-term Amazonian peatland development

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Roucoux, K. H.; Baker, T. R.; Gosling, W. D.; Honorio Coronado, E.; Jones, T. D.; Lahteenoja, O.; Lawson, I. T.

2012-04-01

woodland with abundant Myrtaceae; (4) Expansion of Mauritia/Mauritiella palm swamp vegetation c. 1000 years ago representing establishment of the present day vegetation community. Our results show that the vegetation at this site has undergone continuous change throughout the period of peat formation. The sequence of vegetation development is not straightforward, being characterised by abrupt transitions between vegetation types and reversals in the apparent trajectory of change. Overall this suggests that the system is highly dynamic on centennial to millennial timescales. This complexity may reflect vegetation responses to a combination of external (physical) and internal (biological) drivers and the presence of thresholds in the system. Future investigations will work towards understanding the processes that drive these vegetation transitions and predicting peatland vegetation responses to future climatic change.

Effects of short-rotation controlled burning on amphibians and reptiles in pine woodlands

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Roger W. Perry; D. Craig Rudolph; Ronald E. Thill

2012-01-01

Fire is being used increasingly as a forest management tool throughout North America, but its effects on reptiles and amphibians in many ecosystems are unclear. Open woodlands with understories dominated by herbaceous vegetation benefit many wildlife species, but maintaining these woodlands requires frequent burning. Although many studies have compared herpetofaunal...

Pinyon pine mortality alters communities of ground-dwelling arthropods

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Robert J. Delph; Michael J. Clifford; Neil S. Cobb; Paulette L. Ford; Sandra L. Brantley

2014-01-01

We documented the effect of drought-induced mortality of pinyon pine (Pinus edulis Engelm.) on communities of ground-dwelling arthropods. Tree mortality alters microhabitats utilized by ground-dwelling arthropods by increasing solar radiation, dead woody debris, and understory vegetation. Our major objectives were to determine (1) whether there were changes in...

Effects of liming on forage availability and nutrient content in a forest impacted by acid rain.

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Sarah E Pabian

Full Text Available Acidic deposition and subsequent forest soil acidification and nutrient depletion can affect negatively the growth, health and nutrient content of vegetation, potentially limiting the availability and nutrient content of forage for white-tailed deer (Odocoileus virginianus and other forest herbivores. Liming is a mitigation technique that can be used to restore forest health in acidified areas, but little is known about how it affects the growth or nutrient content of deer forage. We examined the effects of dolomitic limestone application on the growth and chemical composition of understory plants in an acidified forest in central Pennsylvania, with a focus on vegetative groups included as white-tailed deer forage. We used a Before-After-Control-Impact study design with observations 1 year before liming and up to 5 years post-liming on 2 treated and 2 untreated 100-ha sites. Before liming, forage availability and several nutrients were below levels considered optimal for white-tailed deer, and many vegetative characteristics were related to soil chemistry. We observed a positive effect of liming on forb biomass, with a 2.7 fold increase on limed sites, but no biomass response in other vegetation groups. We observed positive effects of liming on calcium and magnesium content and negative effects on aluminum and manganese content of several plant groups. Responses to liming by forbs and plant nutrients show promise for improving vegetation health and forage quality and quantity for deer.

Edge effects on understory epiphytic ferns and epiphyllous bryophytes in moist afromontane forests of Ethiopia

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Hylander Kristoffer

2013-12-01

Full Text Available Most studies on edge effects in tropical forests have been conducted in landscapes with low human population density and in situations where the edges have been left unused after logging of the adjacent area. Here we studied forest margins heavily used by local farmers in a forest/agriculture mosaic landscape in Ethiopia. We compared forest structure and plant species composition across 41 forest-agriculture ecotones from 200 m out into the agricultural area to 200 m into the forest. There are strong edge effects from the edge and into the forest on canopy cover and number of stumps and apparently these forest-agricultural edges are intensively used by humans. They are penetrated by paths, beehives are found in the trees, timber of various dimensions is harvested and there is sometimes substantial cover of perennial wild (or semi-wild crops such as coffee and spices. The number of understory epiphytic fern species as well as number of epiphyllous (i.e., growing on leaves bryophyte species was lower at 20 m than at 75 m from the edge. The number of fern species was higher in newly created edges and thereafter they declined, which indicates an extinction debt. This pattern was not seen for the epiphyllous bryophytes. It is likely that different human management activities are responsible for many of the found edge effects besides wind and sun effects from the edge. Tropical forest margins provide important resources for people in many landscapes. It is important to understand how such use affects the biota of the forests. This study shows that there are substantial edge effects, but that the edge effects do not seem to become worse over time for epiphyllous bryophytes and only slightly so for ferns.

Radiative transfer in shrub savanna sites in Niger: preliminary results from HAPEX-Sahel. 1. Modelling surface reflectance using a geometric-optical approach

International Nuclear Information System (INIS)

Franklin, J.; Duncan, J.; Huete, A.R.; Leeuwen, W.J.D. van; Li, X.; Bégué, A.

1994-01-01

To use optical remote sensing to monitor land surface-climate interactions over large areas, algorithms must be developed to relate multispectral measurements to key variables controlling the exchange of matter (water, carbon dioxide) and energy between the land surface and the atmosphere. The proportion of the ground covered by vegetation and the interception of photosynthetically active radiation (PAR) by vegetation are examples of two variables related to evapotranspiration and primary production, respectively. An areal-proportion model of the multispectral reflectance of shrub savanna, composed of scattered shrubs with a grass, forb or soil understory, predicted the reflectance of two 0.5 km 2 sites as the area-weighted average of the shrub and understory or ‘background’ reflectances. Although the shaded crown and shaded background have darker reflectances, ignoring them in the area-weighted model is not serious when shrub cover is low and solar zenith angle is small. A submodel predicted the reflectance of the shrub crown as a function of the foliage reflectance and amount of plant material within the crown, and the background reflectance scattered or transmitted through canopy gaps (referred to as a soil—plant ‘spectral interaction’ term). One may be able to combine these two models to estimate both the fraction of vegetation cover and interception of PAR by green vegetation in a shrub savanna. (author)

Post-fire vegetation dynamics in Portugal

Science.gov (United States)

Gouveia, C.; Dacamara, C. C.; Trigo, R. M.

2009-04-01

The number of fires and the extent of the burned surface in Mediterranean Europe have increased significantly during the last three decades. This may be due either to modifications in land-use (e.g. land abandonment and fuel accumulation) or to climatic changes (e.g. reduction of fuel humidity), both factors leading to an increase of fire risk and fire spread. As in the Mediterranean ecosystems, fires in Portugal have an intricate effect on vegetation regeneration due to the complexity of landscape structures as well as to the different responses of vegetation to the variety of fire regimes. A thorough evaluation of vegetation recovery after fire events becomes therefore crucial in land management. In the above mentioned context remote sensing plays an important role because of its ability to monitor and characterise post-fire vegetation dynamics. A number of fire recovery studies, based on remote sensing, have been conducted in regions characterised by Mediterranean climates and the use of NDVI to monitor plant regeneration after fire events was successfully tested (Díaz-Delgado et al., 1998). In particular, several studies have shown that rapid regeneration occurs within the first 2 years after the fire occurrences, with distinct recovery rates according to the geographical facing of the slopes (Pausas and Vallejo, 1999). In 2003 Portugal was hit by the most devastating sequence of large fires, responsible by a total burnt area of 450 000 ha (including 280 000 ha of forest), representing about 5% of the Portuguese mainland (Trigo et al., 2006). The aim of the present work is to assess and monitor the vegetation behaviour over Portugal following the 2003 fire episodes. For this purpose we have used the regional fields of the Normalized Difference Vegetation Index (NDVI) as obtained from the VEGETATION-SPOT5 instrument, from 1999 to 2008. We developed a methodology to identify large burnt scars in Portugal for the 2003 fire season. The vegetation dynamics was then

Seasat synthetic aperture radar ( SAR) response to lowland vegetation types in eastern Maryland and Virginia.

Science.gov (United States)

Krohn, M.D.; Milton, N.M.; Segal, D.B.

1983-01-01

Examination of Seasat SAR images of eastern Maryland and Virginia reveals botanical distinctions between vegetated lowland areas and adjacent upland areas. Radar returns from the lowland areas can be either brighter or darker than returns from the upland forests. Scattering models and scatterometer measurements predict an increase of 6 dB in backscatter from vegetation over standing water. This agrees with the 30-digital number (DN) increase observed in the digital Seasat data. The density, morphology, and relative geometry of the lowland vegetation with respect to standing water can all affect the strength of the return L band signal.-from Authors

Effects of N on plant response to heat-wave: a field study with prairie vegetation.

Science.gov (United States)

Wang, Dan; Heckathorn, Scott A; Mainali, Kumar; Hamilton, E William

2008-11-01

More intense, more frequent, and longer heat-waves are expected in the future due to global warming, which could have dramatic ecological impacts. Increasing nitrogen (N) availability and its dynamics will likely impact plant responses to heat stress and carbon (C) sequestration in terrestrial ecosystems. This field study examined the effects of N availability on plant response to heat-stress (HS) treatment in naturally-occurring vegetation. HS (5 d at ambient or 40.5 degrees C) and N treatments (+/-N) were applied to 16 1 m(2) plots in restored prairie vegetation dominated by Andropogon gerardii (warm-season C4 grass) and Solidago canadensis (warm-season C3 forb). Before, during, and after HS, air, canopy, and soil temperature were monitored; net CO2 assimilation (P(n)), quantum yield of photosystem II (Phi(PSII)), stomatal conductance (g(s)), and leaf water potential (Psi(w)) of the dominant species and soil respiration (R(soil)) of each plot were measured daily during HS. One week after HS, plots were harvested, and C% and N% were determined for rhizosphere and bulk soil, and above-ground tissue (green/senescent leaf, stem, and flower). Photosynthetic N-use efficiency (PNUE) and N resorption rate (NRR) were calculated. HS decreased P(n), g(s), Psi(w), and PNUE for both species, and +N treatment generally increased these variables (+/-HS), but often slowed their post-HS recovery. Aboveground biomass tended to decrease with HS in both species (and for green leaf mass in S. canadensis), but decrease with +N for A. gerardii and increase with +N for S. canadensis. For A. gerardii, HS tended to decrease N% in green tissues with +N, whereas in S. canadensis, HS increased N% in green leaves. Added N decreased NRR for A. gerardii and HS increased NRR for S. canadensis. These results suggest that heat waves, though transient, could have significant effects on plants, communities, and ecosystem N cycling, and N can influence the effect of heat waves.

Understory vegetation in reclaimed and unreclaimed post-mining forest stands

Czech Academy of Sciences Publication Activity Database

Mudrák, Ondřej; Frouz, J.; Velichová, V.

2010-01-01

Roč. 36, č. 6 (2010), s. 783-790 ISSN 0925-8574 Institutional research plan: CEZ:AV0Z60050516 Keywords : coal * restoration * succession Subject RIV: EH - Ecology, Behaviour Impact factor: 2.203, year: 2010

Vegetation dynamics and dynamic vegetation science

NARCIS (Netherlands)

Van der Maarel, E

1996-01-01

his contribution presents a review of the development of the study of vegetation dynamics since 1979, in the framework of a jubilee meeting on progress in the study of vegetation. However, an exhaustive review is both impossible and unnecessary. It is impossible within the few pages available

Vegetation survey: a new focus for Applied Vegetation Science

NARCIS (Netherlands)

Chytry, M.; Schaminee, J.H.J.; Schwabe, A.

2011-01-01

Vegetation survey is an important research agenda in vegetation science. It defines vegetation types and helps understand differences among them, which is essential for both basic ecological research and applications in biodiversity conservation and environmental monitoring. In this editorial, we

Biodiversity of Terrestrial Vegetation during Past Warm Periods

Science.gov (United States)

Davies-Barnard, T.; Valdes, P. J.; Ridgwell, A.

2016-12-01

Previous modelling studies of vegetation have generally used a small number of plant functional types to understand how the terrestrial biosphere responds to climate changes. Whilst being useful for understanding first order climate feedbacks, this climate-envelope approach makes a lot of assumptions about past vegetation being very similar to modern. A trait-based method has the advantage for paleo modelling in that there are substantially less assumptions made. In a novel use of the trait-based dynamic vegetation model JeDi, forced with output from climate model HadCM3, we explore past biodiversity and vegetation carbon changes. We use JeDi to model an optimal 2000 combinations of fifteen different traits to enable assessment of the overall level of biodiversity as well as individual growth strategies. We assess the vegetation shifts and biodiversity changes in past greenhouse periods to better understand the impact on the terrestrial biosphere. This work provides original insights into the response of vegetation and terrestrial carbon to climate and hydrological changes in high carbon dioxide climates over time, including during the Late Permian and Cretaceous. We evaluate how the location of biodiversity hotspots and species richness in past greenhouse climates is different to the present day.

The response of Arctic vegetation to the summer climate: relation between shrub cover, NDVI, surface albedo and temperature

Energy Technology Data Exchange (ETDEWEB)

Blok, Daan; Heijmans, Monique M P D; Berendse, Frank [Nature Conservation and Plant Ecology Group, Wageningen University, PO Box 47, 6700 AA, Wageningen (Netherlands); Schaepman-Strub, Gabriela [Institute of Evolutionary Biology and Environmental Studies, University of Zuerich, Winterthurerstrasse 190, 8057 Zuerich (Switzerland); Bartholomeus, Harm [Centre for Geo-Information, Wageningen University, PO Box 47, 6700 AA, Wageningen (Netherlands); Maximov, Trofim C, E-mail: daan.blok@wur.nl [Biological Problems of the Cryolithozone, Russian Academy of Sciences, Siberian Division, 41, Lenin Prospekt, Yakutsk, The Republic of Sakha, Yakutia 677980 (Russian Federation)

2011-07-15

Recently observed Arctic greening trends from normalized difference vegetation index (NDVI) data suggest that shrub growth is increasing in response to increasing summer temperature. An increase in shrub cover is expected to decrease summer albedo and thus positively feed back to climate warming. However, it is unknown how albedo and NDVI are affected by shrub cover and inter-annual variations in the summer climate. Here, we examine the relationship between deciduous shrub fractional cover, NDVI and albedo using field data collected at a tundra site in NE Siberia. Field data showed that NDVI increased and albedo decreased with increasing deciduous shrub cover. We then selected four Arctic tundra study areas and compiled annual growing season maximum NDVI and minimum albedo maps from MODIS satellite data (2000-10) and related these satellite products to tundra vegetation types (shrub, graminoid, barren and wetland tundra) and regional summer temperature. We observed that maximum NDVI was greatest in shrub tundra and that inter-annual variation was negatively related to summer minimum albedo but showed no consistent relationship with summer temperature. Shrub tundra showed higher albedo than wetland and barren tundra in all four study areas. These results suggest that a northwards shift of shrub tundra might not lead to a decrease in summer minimum albedo during the snow-free season when replacing wetland tundra. A fully integrative study is however needed to link results from satellite data with in situ observations across the Arctic to test the effect of increasing shrub cover on summer albedo in different tundra vegetation types.

The response of Arctic vegetation to the summer climate: relation between shrub cover, NDVI, surface albedo and temperature