Impacts of elevated atmospheric CO2 and temperature on plant community structure of a temperate grassland are modulated by cutting frequency PDF Download

Author: H. Harmens
Publisher:
ISBN:
Category :
Languages : en
Pages :

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Author: Martin L. Parry
Publisher: Cambridge University Press
ISBN: 0521880106
Category : Business & Economics
Languages : en
Pages : 71

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IPCC Fourth Assessment Report on climate change impacts, adaptation and vulnerability for researchers, students, policymakers.

Author: Paul C.D. Newton
Publisher: CRC Press
ISBN: 1420003828
Category : Nature
Languages : en
Pages : 380

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Agroecosystems in a Changing Climate considers the consequences of changes in the atmosphere and climate on the integrity, stability, and productivity of agroecosystems. The book adopts a novel approach by bringing together theoretical contributions from ecologists and the applied interpretations of agriculturalists. Drawing these two approa

Author: J. Lloveras
Publisher:
ISBN:
Category : Grasslands
Languages : en
Pages : 882

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Author: Troy Shaun Dunn
Publisher:
ISBN:
Category : Grassland ecology
Languages : en
Pages : 59

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Community structure is being altered by direct and indirect effects of climate change. Increasing temperatures can threaten community structure resulting in the disruption of interactions within those communities most sensitive to changes in climate. Among those communities at risk for change is the North American grassland habitat and its resident insect community. Climate change can potentially affect primary production and the abundance and diversity of both plants and animals in different ecosystems. Here we have used open-top chambers to study the impact warming temperatures have on the resident plant and insect community on grassland habitat in order to better understand how grassland areas are affected and may change as a result of global warming, and how climate change will impact the community and ecosystem as a whole. Results show that passively warmed open-top chambers have a measureable increase of 1-4°C in ambient temperature above that of the controls. Results also show no significant treatment effects of temperature on primary production, except for litter, and no significant effect on the abundances of the resident insect community as a whole. Interestingly, results do reveal significant effects of treatment on insect taxonomic orders and families as well as significant effects on the trophic levels within the grassland habitat confirming that insects are responding in different ways to artificial warming, which can ultimately alter trophic dynamics directly and indirectly.

Author:
Publisher:
ISBN:
Category :
Languages : en
Pages : 6

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

Author: United States. Department of Energy
Publisher:
ISBN:
Category :
Languages : en
Pages : 18

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Author: David J. Gibson
Publisher: Cambridge University Press
ISBN: 1107195268
Category : Nature
Languages : en
Pages : 363

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A comprehensive assessment of the effects of climate change on global grasslands and the mitigating role that ecologists can play.

Author:
Publisher:
ISBN:
Category :
Languages : en
Pages :

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Two of the most important and pervasive greenhouse gases driving global change and impacting forests in the U.S. and around the world are atmospheric CO2 and tropospheric O3. As the only free air, large-scale manipulative experiment studying the interaction of elevated CO2 and O3 on forests, the Aspen FACE experiment was uniquely designed to address the long-term ecosystem level impacts of these two greenhouse gases on aspen-birch-maple forests, which dominate the richly forested Lake States region. The project was established in 1997 to address the overarching scientific question: "What are the effects of elevated [CO2] and [O3], alone and in combination, on the structure and functioning of northern hardwood forest ecosystems?" From 1998 through the middle of the 2009 growing season, we examined the interacting effects of elevated CO2 and O3 on ecosystem processes in an aggrading northern forest ecosystem to compare the responses of early-successional, rapid-growing shade intolerant trembling aspen and paper birch to those of a late successional, slower growing shade tolerant sugar maple. Fumigations with elevated CO2 (560 ppm during daylight hours) and O3 (approximately 1.5 x ambient) were conducted during the growing season from 1998 to 2008, and in 2009 through harvest date. Response variables quantified during the experiment included growth, competitive interactions and stand dynamics, physiological processes, plant nutrient status and uptake, tissue biochemistry, litter quality and decomposition rates, hydrology, soil respiration, microbial community composition and respiration, VOC production, treatment-pest interactions, and treatment-phenology interactions. In 2009, we conducted a detailed harvest of the site. The harvest included detailed sampling of a subset of trees by component (leaves and buds, fine branches, coarse branches and stem, coarse roots, fine roots) and excavation of soil to a depth of 1 m. Throughout the experiment, aspen and birch photosynthesis increased with elevated CO2 and tended to decrease with elevated O3, compared to the control. In contrast to aspen and birch, maple photosynthesis was not enhanced by elevated CO2. Elevated O3 did not cause significant reductions in maximum photosynthesis in birch or maple. In addition, photosynthesis in ozone sensitive clones was affected to a much greater degree than that in ozone tolerant aspen clones. Treatment effects on photosynthesis contributed to CO2 stimulation of aboveground and belowground growth that was species and genotype dependent, with birch and aspen being most responsive and maple being least responsive. The positive effects of elevated CO2 on net primary productivity NPP were sustained through the end of the experiment, but negative effects of elevated O3 on NPP had dissipated during the final three years of treatments. The declining response to O3 over time resulted from the compensatory growth of O3-tolerant genotypes and species as the growth of O3-sensitive individuals declined over time. Cumulative NPP over the entire experiment was 39% greater under elevated CO2 and 10% lower under elevated O3. Enhanced NPP under elevated CO2 was sustained by greater root exploration of soil for growth-limiting N, as well as more rapid rates of litter decomposition and microbial N release during decay. Results from Aspen FACE clearly indicate that plants growing under elevated carbon dioxide, regardless of community type or ozone level, obtained significantly greater amounts of soil N. These results indicate that greater plant growth under elevated carbon dioxide has not led to "progressive N limitation". If similar forests growing throughout northeastern North America respond in the same manner, then enhanced forest NPP under elevated CO2 may be sustained for a longer duration than previously thought, and the negative effect of elevated O3 may be diminished by compensatory growth of O3-tolerant plants as they begin to dominate forest communities ...

Author: Boyd R. Strain
Publisher:
ISBN: 9781410222237
Category : Science
Languages : en
Pages : 316

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Book Description
Carbon dioxide (CO2) enhancement of plant growth is one important direct effect of rising atmospheric CO2. Through photosynthesis, plants produce food and fiber from light and carbon assimilated as CO2 and form the foundation of the Earth's life support system. Rising atmospheric CO2 is thus an essential input to the food-producing process, and effects of CO2 enrichment described in this document have far-reaching implications for agricultural and ecological productivity. Establishing an empirical foundation of plant response to more CO2 and developing the capability to predict crop and ecosystem responses to CO2 enrichment are research goals that have been pursued in the DOE-led program. This State-of-the-Art report on the direct effects of CO2 on vegetation summarizes the current state of knowledge; it identifies uncertainties and suggests where more research is needed to assure understanding and delineates data and modeling requirements for future predictions. Important progress has been made over the past 5 years since the plant science community urged that more attention be given to direct effects of CO2 enrichment. Enhanced plant growth and yield from more CO2 is now widely recognized in different scientific and public sectors as an important element of the CO2 problem. While there have been gains in knowledge about a few crop plants, considerable ignorance remains about responses of native species and ecosystems to CO2 enrichment. Only a few native species or ecosystem types have been investigated. Competition among species in relation to CO2-induced growth differences is essentially unknown. Many interactions involving CO2 enrichment and other physical and biological variables affecting plant growth have not been studied. Among the physiological processes directly affected by CO2 that are not well understood are those involving net transpiration and whole-plant water use, where CO2 reduces stomatal conductance but increases leaf size. Nutrient requirements to sustain increased photosynthesis and growth at enriched levels of CO2 are not understood. This State-of-the-Art volume examines some key responses and identifies research needed to resolve these and other key unknowns.