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Author: Publisher: ISBN: Category : Languages : en Pages :
Book Description
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: Publisher: ISBN: Category : Languages : en Pages :
Book Description
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: Publisher: ISBN: Category : Languages : en Pages :
Book Description
Rising concentrations of atmospheric CO2 and O3 are altering the structure and function of forest ecosystems. Herbivorous insects are the major consumers in temperate deciduous forests, with the capacity to dramatically alter tree growth (via outbreaks), forest community composition and ecosystem dynamics (e.g., nutrient cycling). Until recently, however, experimental quantification of the impacts of CO2 and O3 on canopy herbivore communities and rates of defoliation and nutrient flux has not been addressed. This research, conducted at the Aspen FACE (Free Air CO2 Enrichment) facility in northern Wisconsin, U.S.A., evaluated the independent and interactive effects of CO2 and O3 on (1) the abundance and diversity of forest canopy insect communities, and (2) rates of insect herbivory and transfer of material (leaf greenfall and insect frass) from the canopy to the forest floor. Results of studies of individual insects revealed that elevated CO2 and O3 influence the performance of individual species of damaging insect pests, but the magnitude of impact is influenced by both insect species and their host tree species. Censuses of canopy insects showed that some species were positively affected, some negatively affected, and some not affected by elevated CO2 and O3. Moreover, overall species diversity was generally not strongly affected by CO2 and O3. In summary, the effects of CO2 and O3 on forest insects is highly variable among species and over time, and thus difficult to generalize across broad taxonomic groups. Estimates of foliar damage revealed that CO2 and O3 have pronounced effects on canopy damage by insect herbivores. Averaged over three years, foliar biomass lost to insect feeding increased 86% in high CO2 environments and decreased 12% in high O3 environments. The increases/decreases were greater for aspen than for birch, indicating that the selective pressure of insects will shift across tree species in forests of the future. Herbivore-mediated material (green leaf tissue, insect frass) transfer from the canopy to the forest floor increased 37% in elevated CO2 and decreased 21% in elevated O3. Nitrogen transfers paralleled those results: 39% increase in elevated CO2 and 19% decrease in elevated O3.
Author: Seppo Kellomaki Publisher: CRC Press ISBN: 1351678949 Category : Nature Languages : en Pages : 347
Book Description
In many places in the world, forests dominate landscapes and provide various products. Future climate change could profoundly alter the productivity of forest ecosystems and species composition. Until now, climate impact research has primarily focused on the likely impacts of rise in temperature, increased atmospheric CO2 concentration, and varying precipitation on unmanaged forests. The issue that now needs to be addressed is how to sustainably manage climate change for timber production and biomass. Though climate change is a global issue, impacts on forests depend on local environmental conditions and management methods, so this book will look at the issue under varying local contexts.
Author: Publisher: Newnes ISBN: 0080983421 Category : Technology & Engineering Languages : en Pages : 647
Book Description
There are significant pressures from climate change and air pollution that forests currently face. This book aims to increase understanding of the state and potential of forest ecosystems to mitigate and adapt to climate change in a polluted environment. It reconciles process-oriented research, long-term monitoring and applied modeling through comprehensive forest ecosystem research. Furthermore, it introduces "forest super sites for research for integrating soil, plant and atmospheric sciences and monitoring. It also provides mechanistic and policy-oriented modeling with scientifically sound risk indications regarding atmospheric changes and ecosystem services. Identifies current knowledge gaps and emerging research needs Highlights novel methodologies and integrated research concepts Assesses ecological meaning of investigations and prioritizing research need
Author: Rihard L. Lindroth Publisher: ISBN: Category : Languages : en Pages :
Book Description
The overall purpose of this research was to evaluate the independent and interactive effects of elevated levels of CO{sub 2} and O{sub 3} on tree leaf litter quality and decomposition. This research was conducted at the Aspen FACE (Free Air CO{sub 2} Enrichment) facility near Rhinelander, Wisconsin. This research comprised one facet of a larger project assessing how CO{sub 2} and O{sub 3} pollutants will alter carbon sequestration and nutrient cycling in north temperate forest ecosystems.
Author: Dieter Overdieck Publisher: Springer ISBN: 981101860X Category : Science Languages : en Pages : 247
Book Description
This comprehensive book discusses the ecophysiological features of trees affected by the two most prominent factors of climate change: atmospheric CO2 concentration and temperature. It starts with the introduction of experimental methods at the leaf, branch, the whole-tree, and tree group scales, and in the following chapters elaborates on specific topics including photosynthesis of leaves, respiration of plant organs, water use efficiency, the production of and/or distribution patterns of carbohydrates, secondary metabolites, and nutrients, anatomy of cells and tissues, height and stem-diameter growth, biomass accumulation, leaf phenology and longevity, and model ecosystems (soil-litter-plant enclosures). The current knowledge is neatly summarized, and the author presents valuable data derived from his 30 years of experimental research, some of which is published here for the first time. Using numerous examples the book answers the fundamental questions such as: What are the interactions of elevated CO2 concentration and temperature on tree growth and matter partitioning? How do different tree groups react? Are there any effects on organisms living together with trees? What kinds of models can be used to interpret the results from experiments on trees? This volume is highly recommended for researchers, postdocs, and graduate students in the relevant fields. It is also a valuable resource for undergraduate students, decision-makers in the fields of forest management and environmental protection, and any other scientists who are interested in the effect of global change on ecosystems.
Author: Kurt S. Pregitzer Publisher: Elsevier Inc. Chapters ISBN: 0128055626 Category : Nature Languages : en Pages : 27
Book Description
The Aspen free-air carbon dioxide (CO2) enrichment (FACE) experiment tested how three developing forest communities responded to elevated concentrations of CO2 and/or tropospheric ozone (O3). Throughout the 11-year experiment, elevated CO2 increased aboveground productivity, whereas the initial negative effects of elevated O3 on aboveground productivity became insignificant over time. During the first 2 years, fine root biomass and soil respiration responded positively to elevated CO2 and negatively to elevated O3. However, after 5 years, O3 effects on fine root biomass were weakly negative or positive and effects on soil respiration were positive. Despite altering litter inputs, neither elevated O3 nor elevated CO2 affected overall soil C storage at the end of the experiment, consistent with observations that elevated CO2 increased and elevated O3 tended to decrease the activity of litter-degrading extracellular enzymes. Overall, our understanding of belowground processes is still insufficient to predict how ecosystems will respond to global change.
Author: J. Puhe Publisher: Springer Science & Business Media ISBN: 3642595316 Category : Science Languages : en Pages : 604
Book Description
The inclusion of forests as potential biological sinks in the Kyoto Protocol to the United Nations Framework Convention on Climate Change (UNFCCC) in 1997 has attracted international attention and again has put scientific and political focus on the world's forests, regarding their state and development. The international discus sion induced by the Kyoto Protocol has clearly shown that not only the tropical rain forests are endangered by man's activities, but also that the forest ecosystems of boreal, temperate, mediterranean and subtropical regions have been drastically modified. Deforestation on a large scale, burning, over-exploitation, and the degra dation of the biological diversity are well-known symptoms in forests all over the world. This negative development happens in spite of the already existing knowledge of the benefits of forests on global energy and water regimes, the biogeochemical cycling of carbon and other elements as well as on the biological and cultural diversity. The reasons why man does not take care of forests properly are manifold and complex and there is no easy solution how to change the existing negative trends. One reason that makes it so difficult to assess the impacts of human activity on the future development of forests is the large time scale in which forests react, ranging from decades to centuries.