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Author: Publisher: ISBN: Category : Languages : en Pages : 408
Book Description
ABSTRACTShifting patterns of precipitation associated with climate change may affect water-limited ecosystems to a greater degree than atmospheric CO2 or temperature changes, yet we lack a mechanistic understanding of the effects of water in these ecosystems. In water-limited ecosystems, annual net primary productivity correlates strongly with total annual precipitation. However, precipitation in these ecosystems arrives in episodic events, suggesting that biophysical investigations should focus on the implications of discrete precipitation events. Further, examining dynamics of ecosystem processes over a period of days or weeks promises to link our leaf-level mechanistic understandings with larger scale patterns and temporal dynamics of ecosystem photosynthetic CO2 uptake, respiration and evapotranspiration. The objectives of this dissertation were to quantify: (1) the influence of biotic and abiotic features of an ecosystem (e.g., species composition and soil physical characteristics) on short-term patterns of resilience and resistance to a precipitation pulse; (2) the role of antecedent climatic conditions and the seasonal timing of rainfall in limiting ecosystem carbon exchange in response to precipitation events; and (3) the effect of changes in woody plant abundance on seasonal ecosystem carbon dynamics in relation to the North American Monsoon. Major findings and contributions of this research include defining the concepts of ecosystem functional resistance and resilience and their implications in the presence of a dominant nonnative bunchgrass in semi-arid grasslands (Appendix A); a better understanding of the influence of warm-season precipitation variability and the seasonal timing of rainfall on ecosystem carbon dynamics in a semi-arid grassland (Appendix B); the use of flux duration analysis, a novel approach to analyzing ecosystem carbon and water flux time-series data to distinguish between"pulse-driven"or"steady-state"ecosystems (Appendix C); and, finally, the application of flux duration analysis to quantify the sensitivity of ecosystem carbon exchange in response to seasonal rainfall in a riparian grassland and shrubland and the role that plant functional type diversity may play in constraining carbon exchange sensitivity (Appendix D).
Author: Publisher: ISBN: Category : Languages : en Pages : 408
Book Description
ABSTRACTShifting patterns of precipitation associated with climate change may affect water-limited ecosystems to a greater degree than atmospheric CO2 or temperature changes, yet we lack a mechanistic understanding of the effects of water in these ecosystems. In water-limited ecosystems, annual net primary productivity correlates strongly with total annual precipitation. However, precipitation in these ecosystems arrives in episodic events, suggesting that biophysical investigations should focus on the implications of discrete precipitation events. Further, examining dynamics of ecosystem processes over a period of days or weeks promises to link our leaf-level mechanistic understandings with larger scale patterns and temporal dynamics of ecosystem photosynthetic CO2 uptake, respiration and evapotranspiration. The objectives of this dissertation were to quantify: (1) the influence of biotic and abiotic features of an ecosystem (e.g., species composition and soil physical characteristics) on short-term patterns of resilience and resistance to a precipitation pulse; (2) the role of antecedent climatic conditions and the seasonal timing of rainfall in limiting ecosystem carbon exchange in response to precipitation events; and (3) the effect of changes in woody plant abundance on seasonal ecosystem carbon dynamics in relation to the North American Monsoon. Major findings and contributions of this research include defining the concepts of ecosystem functional resistance and resilience and their implications in the presence of a dominant nonnative bunchgrass in semi-arid grasslands (Appendix A); a better understanding of the influence of warm-season precipitation variability and the seasonal timing of rainfall on ecosystem carbon dynamics in a semi-arid grassland (Appendix B); the use of flux duration analysis, a novel approach to analyzing ecosystem carbon and water flux time-series data to distinguish between"pulse-driven"or"steady-state"ecosystems (Appendix C); and, finally, the application of flux duration analysis to quantify the sensitivity of ecosystem carbon exchange in response to seasonal rainfall in a riparian grassland and shrubland and the role that plant functional type diversity may play in constraining carbon exchange sensitivity (Appendix D).
Author: Jianping Huang Publisher: World Scientific ISBN: 9811276196 Category : Science Languages : en Pages : 655
Book Description
Semi-arid regions are ecological security barriers that prevent arid regions from expanding and turning into deserts. The expansion of arid regions and desertification seriously threaten ecological security, and human society cannot achieve sustainable development in an insecure ecological environment. As the transitional zone between arid and humid regions, semi-arid regions lay the foundation of ecological safety for the development of human society.This book provides an overview of processes and mechanisms that characterize semi-arid climate change both regionally and globally. It explains systematically theoretical concepts , including land-atmosphere interactions, ocean-atmosphere interactions, and factors that contribute to climate change, including the impact of human activities. A summary of recent progress in the research in the field and the future of semi-arid regions are also discussed.This book is a specialized monograph and textbook for graduate students of Earth sciences. It is also suitable for undergraduate or graduate students in related majors such as those engaged in atmospheric science, climate change studies, and Earth sciences.
Author: Niall Patrick Hanan Publisher: Frontiers Media SA ISBN: 283254696X Category : Science Languages : en Pages : 174
Book Description
We are now entering the third decade of the 21st century, and recent drylands-focused research has led to major advances in our understanding of the coupled roles of climatic, edaphic, biotic, and anthropogenic processes in dryland ecosystem function, degradation, and sustainable management. Frontiers has organized a series of Research Topics to highlight the latest advancements in science in order to be at the forefront of science in different fields of research. This editorial initiative, led by Professor Niall Hanan, Specialty Chief Editor of the Drylands section, together with Dr. Lindsay Hutley, is focused on new insights, novel developments, current challenges, latest discoveries, recent advances, and future perspectives in the drylands field.
Author: Jake F. Weltzin Publisher: University of Arizona Press ISBN: 9780816522477 Category : Science Languages : en Pages : 264
Book Description
By the beginning of the twenty-first century, few people could deny the reality of global change. But while most alarm has been over increasing temperatures, other changes are occurring in precipitation patternsÑvariations that may be due in part to global warming but also to factors such as changes in atmospheric circulation and land surfaces. This volume provides a central source of information about this newly emerging area of global change research. It presents ongoing investigations into the responses of plant communities and ecosystems to the experimental manipulation of precipitation in a variety of field settingsÑparticularly in the western and central United States, where precipitation is already scarce or variable. By exploring methods that can be used to predict responses of ecosystems to changes in precipitation regimes, it demonstrates new approaches to global change research and highlights the importance of precipitation regimes in structuring ecosystems. The contributors first document the importance of precipitation, soil characteristics, and soil moisture to plant life. They then focus on the roles of precipitation amount, seasonality, and frequency in shaping varied terrestrial ecosystems: desert, sagebrush steppe, oak savanna, tall- and mixed-grass prairie, and eastern deciduous forest. These case studies illustrate many complex, tightly woven, interactive relationships among precipitation, soils, and plantsÑrelationships that will dictate the responses of ecosystems to changes in precipitation regimes. The approaches utilized in these chapters include spatial comparisons of vegetation structure and function across different ecosytems; analyses of changes in plant architecture and physiology in response to temporal variation in precipitation; experiments to manipulate water availability; and modeling approaches that characterize the relationships between climate variables and vegetation types. All seek to assess vegetation responses to major shifts in climate that appear to be occurring at present and may become the norm in the future. As the first volume to discuss and document current and cutting-edge concepts and approaches to research into changing precipitation regimes and terrestrial ecosystems, this book shows the importance of developing reliable predictions of the precipitation changes that may occur with global warming. These studies clearly demonstrate that patterns of environmental variation and the nature of vegetation responses are complex phenomena that are only beginning to be understood, and that these experimental approaches are critical for our understanding of future change.
Author: Christopher Allen Stanbery Publisher: ISBN: Category : Soils Languages : en Pages : 69
Book Description
"Soil inorganic carbon (SIC) constitutes approximately 40% of terrestrial soil carbon and is an integral part of the global carbon cycle; however, the controls on the storage and flux of inorganic carbon are poorly understood. Soil forming factors controlling SIC storage and flux include climate, organisms, relief, parent material, and time (Jenny, 1941). Rainfall is a primary factor controlling SIC accumulation in arid and semi-arid regions, but the hierarchy of controls on SIC development is complex. The Reynolds Creek Experimental Watershed in southwestern Idaho is an ideal location to study factors influencing SIC, as the carbon pool transitions from predominately inorganic carbon in the lower elevations, to organic carbon at higher elevations. This study builds upon fundamental studies in soil science that define and describe precipitation controls on the 'pedocal' (calcic) to 'pedalfer' (non-calcic) soil transition (e.g. Marbut, 1935; Jenny, 1941) by both defining the precipitation boundary in Reynolds Creek, and quantifying the amount of carbon storage within calcic soils. We collected soil samples from soils developed under a wide range of soil-forming regimes: 1) along a precipitation gradient, 2) within different vegetation communities (sagebrush species (Artimesia spp), bitterbrush (Purshia tridentata), greasewood (Sarcobatus vermiculatus), and juniper (Juniperus occidentalis)) 3) from different parent materials (granite, basalt, other volcanics, and alluvium) and 4) from terrace surfaces of different ages. Our results show SIC does not accumulate above a threshold of ~500 mm mean annual precipitation, and variability in SIC below that value is significant. Soil inorganic carbon content from ~1 m deep soil pits and cores at 71 sites shows that 64 sites contained less than 10 kg/m2 SIC, 5 sites contained between 10-20 kg/m2, and 2 sites had between 24 and 29 kg/m2. Random forest modeling and multiple linear regression of the environmental controls on SIC indicate that precipitation is the primary control on SIC accumulation, where increased precipitation correlates with lower amounts of SIC. Elevation is an effective predictor of SIC, as it is strongly auto-correlated with precipitation and vegetation. Parent material consistently ranks as an important predictor in random forest analysis; however, we were unable to quantify the importance of wind-blown dust in the soil profiles, which we believe plays a vital role in SIC accumulation. Despite a recognition of different stages of carbonate development and accumulation rates between gravelly and non-gravelly soils, studies often ignore carbonate coatings on gravels in measurements of soil inorganic carbon (SIC). By quantifying and differentiating the fine (2 mm) and coarse (>2 mm) fractions of SIC in the Reynolds Creek Experimental Watershed in southwestern Idaho, we show that gravel coatings contain up to 44% of total SIC at a given site. Among the 26 soil sites examined throughout the watershed, an average of 13% of the total SIC is stored as carbonate coasts within in the gravel fraction. We measured a high level of pedon-scale field variability (up to 220%) among the three faces of 1 m3 soil pits. Analytical error associated with the modified pressure calcimeter (0.001-0.014%), is considerably less than naturally occurring heterogeneities in SIC within the soil profile. This work highlights and quantifies two sources of uncertainty in studies of SIC needed to inform future research. First, in gravelly sites, the >2 mm portion of soils may store a large percentage of SIC. Second, SIC varies considerably at the pedon-scale, so studies attempting to quantify carbon storage over landscape scales need to consider this variability. This study creates a framework for understanding SIC in Reynolds Creek that may be applied to future work.."--Boise State University ScholarWorks.
Author: Timothy Dube Publisher: Elsevier ISBN: 0443217300 Category : Technology & Engineering Languages : en Pages : 458
Book Description
Remote Sensing of Climate provides cutting-edge techniques in remote sensing of climate variability and the environment. The book focuses on methods and data analytics, advancements in scientific research in the field, and further proffers recommendations on the possible knowledge gaps and future scientific research directions. It covers eight key themes of remote sensing and climate variability, including discussions on how the various aspects from each chapter of the themes interrelate. It also integrates several divergent perspectives on remote sensing and climate variability and the environment to show the interrelationships between the perspectives. This is an important reference for those in education and research working on remote sensing and climate science who need methods, data analytics, case studies, research strides, and key knowledge gaps in the field. Discusses advancements and future research directions in remote sensing for climate variability in a variety of environments Includes simplified and condensed methodologies and data analytics Provides case studies on remote sensing of climate variability, both of the Northern hemisphere temperate systems which are little affected by climate variability, and the greater-impacted global south
Author: Xiaoming Kang Publisher: Frontiers Media SA ISBN: 2832547753 Category : Science Languages : en Pages : 320
Book Description
Forest and grassland ecosystems are the most important carbon sinks in terrestrial ecosystems. They can maintain or enhance carbon stocks and sinks in biomass, and play vital roles in mitigating climate change. China is taking action to achieve its carbon peak and carbon-neutral targets. Climate change, particularly the increase in the frequency, severity, and extent of drought, will affect the stability of the forest and grassland. How forests and grassland mitigate and adapt to climate change is still a challenge. Exploring the response of the forest and grassland to extreme climate events contributes to improving vegetation quality and enhancing the ability to respond to climate change.
Author: Publisher: ISBN: Category : Languages : en Pages : 356
Book Description
Precipitation, more than any other environmental factor, controls patterns of ecosystem production and biogeochemical cycling in arid and semiarid environments. Growing-season rains in these regions are highly unpredictable as they come in intermittent pulses varying in size, frequency and spatial extent, thereby producing unique hydrological patterns that constrain the location and residence time of soil water available for biological activity. In order to understand how arid and semiarid ecosystems respond to inputs of precipitation within the context of ecosystem science and global change studies, knowledge is needed on how plants and other organisms respond as an integrated system to such environmental control. The focus of my research was to understand how the distribution of precipitation events influences the dynamics of carbon cycling in semiarid ecosystems. At a semiarid riparian woodland, measurements of CO2 exchange and evapotranspiration revealed that following precipitation events occurring soon after prolonged dry periods the efficiency of rain-use (amount of carbon gain per unit of precipitation over a specific period time) was low. Precipitation did not readily stimulate primary productivity, water was mainly lost as soil evaporation and large respiratory CO2 effluxes were observed. This commonly observed features in seasonally dry ecosystems might have profound consequences for the seasonal and annual carbon balance. In this woodland, 47% of the precipitation within a single growing season (May-October) was returned to atmosphere as soil evaporation and the CO2 efflux observed just during the first rainy month (July) was equivalent to almost 50% of the net carbon gain observed over the six-month growing season. Results from experimental irrigations in understory plots of riparian mesquite woodland revealed that the magnitude and duration of the large CO2 fluxes occurring soon after rainfall was higher in plots located under tree canopies where, relative to intercanopy plots, the amount of plant litter was higher, soil evaporation and plant photosynthetic rates were lower. Efficiency of rain-use in semiarid ecosystems during the growing season apparently was determined by the degree of coupling between gross photosynthesis and ecosystem respiration, by the fraction of precipitation lost as soil evaporation and by the water-use efficiency of the component vegetation.
Author: National Research Council Publisher: National Academies Press ISBN: 0309183359 Category : Science Languages : en Pages : 41
Book Description
The warming of the Earth has been the subject of intense debate and concern for many scientists, policy-makers, and citizens for at least the past decade. Climate Change Science: An Analysis of Some Key Questions, a new report by a committee of the National Research Council, characterizes the global warming trend over the last 100 years, and examines what may be in store for the 21st century and the extent to which warming may be attributable to human activity.
Author: 
Author: 
Author: Jianping Huang
Author: Niall Patrick Hanan
Author: Jake F. Weltzin
Author: Christopher Allen Stanbery
Author: Timothy Dube
Author: Justus Freiherr von Liebig
Author: Xiaoming Kang
Author: 
Author: National Research Council