Download or read book Ecosystem Sensitivity to Variation in Precipitation and Defoliation Across Grasslands of Alberta written by Batbaatar Amgaa and published by . This book was released on 2021 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Climate models project a greater likelihood of increases in precipitation variability and droughts over the Great Plains of North America. Drought's interactions with other co-occurring factors, such as grazing, can lead to substantial and long-lasting changes to ecosystem goods and services. In this thesis, I examine variations in precipitation and defoliation to better understand how their interactive effects shape ecosystem structure and function. First, I test the effects of grazing on ecosystem sensitivity to precipitation using spatially extensive long-term records of aboveground net plant productivity (ANPP) and precipitation. I found that grazing increased ANPP sensitivity to interannual variability in precipitation, especially at arid grasslands, suggesting that the explanatory power of the precipitation-ANPP relationship may not hold for ecosystems subjected to two or more global change drivers. Second, I examine the commonly assumed but little tested hypothesis - that drought impacts are progressive through time. I do so using a factorial experiment crossing drought and defoliation that I conducted at seven northern temperate grasslands over four years. I found that multi-year drought led to greater changes to community composition than productivity, and effects did not compound through time. Shifts in species composition were driven by variation in the abundance of dominant species, which also likely resulted in stability in ANPP under drought. Third, I examine the sensitivity of both shoot and root biomass to the combined effects of drought and defoliation. This topic is important because root responses are often overlooked in ecosystem models. I found that ANPP increased under drought relative to the ambient treatment, and the combined effects of drought and defoliation reduced ANPP but had no impacts on root biomass. Moreover, using minirhizotrons, I further examine root length dynamics in response to drought and defoliation at two of my seven field sites. I found root length dynamics were affected by every factor manipulated or measured in this thesis. In general, I found decreases in length, production, and lifespan of roots with drought in the shallow soil depth in the absence of defoliation. Notably, I found that the two sites exhibited general convergence in many aspects of their root length dynamics when exposed to both drought and defoliation, but when differences existed, they occurred under the ambient condition or at the deep soil depth. Further, the mortality and lifespan of roots were the aspects of root length dynamics that caused the observed shifts in total root length resulting from drought and variation in defoliation. In sum, this thesis demonstrates that northern temperate grasslands are highly resistant to a reduction in water availability via stability among dominant species or root responses, particularly root length dynamics, but defoliation, regardless of what regime, makes these systems sensitive to drought. Further, my results emphasize that the combined effects of global change drivers on plant root and shoot responses must be included in ecosystem models and will more accurately project ecosystem sensitivity to future variable weather.

Download or read book Biological Soil Crusts in Alberta s Grasslands written by Megan Courtney Lewis and published by . This book was released on 2022 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Biological soil crusts (BSCs) play a central role in the biodiversity, health, resilience, and function of drylands like Alberta's grasslands. In Alberta, much of the biocrust cover consists of lichens, and many crusts are dominated by species of Cladonia. Despite the drought-resistant nature of biocrusts, they have been found to be sensitive to changes in precipitation and disturbance in other regions. This finding leads to questions of if, and how, land-management strategies should change to retain rangeland function as drought becomes more frequent. To answer these questions we need monitoring and experiments investigating biocrust response to change. However, for a group of lichens in Alberta's grassland biocrusts, the Cladonia cariosa group, taxonomic boundaries are imprecise, potentially obscuring changes in biocrust communities. To clarify boundaries in the Cladonia cariosa group, I implemented an integrative taxonomic study using morphology, secondary chemistry, a multi-locus molecular dataset, and a genotype-by-sequencing (GBS) dataset. While the multi-locus study using the internal transcribed spacer region of nuclear rDNA (ITS) and DNA-dependent RNA polymerase 2 (rpb2) provided low resolution, the GBS dataset generated a highly-supported phylogeny. Three lineages corresponded to previously described species in the group, Cladonia cariosa, Cladonia symphycarpa, and Cladonia acuminata, and two lineages correspond to undescribed species. While Cladonia cariosa, Cladonia symphycarpa, and Cladonia acuminata could clearly be differentiated by morphology and chemistry, the two undescribed species had few distinguishing traits from Cladonia symphycarpa, and are thought to be semi-cryptic. This work results in the addition of two putative species to the Cladonia cariosa group. One of the new putative species, for now referred to as Clade E, occurs in Alberta along with Cladonia cariosa, Cladonia symphycarpa, Cladonia acuminata, and Cladonia decorticata; while the second new putative species, Clade F, appears to have a distribution limited to Europe. Following clarification of species boundaries, I assessed the effects of simulated drought and grazing on grassland BSC using a manipulative experiment conducted over four years at seven North American temperate grassland sites. A 45% reduction in precipitation and four defoliation treatments simulating common grazing management systems were applied to study responses of biological soil crust cover and community composition, as well as environmental variables. Effects differed by site, with BSC lichen and moss experiencing an increase in cover with defoliation at some sites, but seemed largely resistant to drought treatments. Selaginella densa was sensitive to combined effects of drought and defoliation at some sites, experiencing the largest cover decrease in drought and spring+fall defoliated plots. Both moss and lichen cover were found to have a negative relationship with litter. Lichen had a positive relationship with light at a site with high annual net primary production (ANPP) and a negative relationship with light at a site with low ANPP. Beta-diversity in BSC communities was found to be significantly higher in undefoliated treatments, and lower in spring+fall defoliated treatments. The varying effects of drought and defoliation on BSC by site highlights the importance of using ecological knowledge to make landscape management decisions, and that one-size-fits-all management approaches for grasslands in the Great Plains region are likely innapropriate. This research has greatly expanded our understanding of the phylogenetics of the Cladonia cariosa group, which is ubiquitous in our area of the Great Plains, as well as the influence of drought and defoliation on BSC composition and cover.

Download or read book Sensitivity of Grassland Ecosystems Across the Great Plains to Present and Future Variability in Precipitation written by Jana Lynn Heisler and published by . This book was released on 2008 with total page 322 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Grassland Responses to Global Change written by Evan Elliot Batzer and published by . This book was released on 2020 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: The recent history of the Earth's biosphere -- the Anthropocene -- is characterized by human activity. Increasingly, industrialization, land use change, fossil fuel combustion, and other drivers have altered key biological processes that govern the composition and function of natural communities. Among the two most impactful stressors are increased concentrations of limiting soil nutrients and shifting patterns of temperature and precipitation through climate change. Grasslands, like many plant ecosystems, are highly sensitive to these changes. Their widespread distribution and importance to both conservation and human enterprise underscores the need to understand how these global changes operate in grassland systems. However, climate change and nutrient deposition are known to produce complex effects on plant community structure; to effectively predict vegetation change, studies must integrate across multiple stressors, mechanisms, and scales of interest. This dissertation contributes to a deeper understanding of these complexities through a synthesis of large-scale experimentation and novel statistical methodology. Chapter 1 uses data from a global experimental cooperative -- the Nutrient Network -- to test contrasting hypotheses about compositional change driven by soil nutrient enrichment. While traditional perspectives on resource competition suggest that nutrient enrichment controls plant species abundances through increasing limitation by light, experimental evidence indicates that other mechanisms related to trade-offs in the use of specific soil resources may also be an important driver. Across 49 experimental sites, there was strong support for a "neutral" model, where plants respond similarly to the increased availability of soil nitrogen, phosphorous, or potassium. However, I also find that responses to treatments were more varied in sites characterized by higher average productivity and pre-treatment light limitation. Together, these findings indicate that grassland responses to fertilization tend to be driven by a trade-off between belowground and aboveground resource use, yet the predictability of these effects will depend on the inherent productivity and community structure of a given site. Chapters 2 and 3 focus on California grasslands. Chapter 2 explores the effects of nitrogen enrichment on plant community diversity at multiple scales of organization, highlighting how shifts in community structure and distribution shape observed diversity loss at different sampling areas. Most nutrient addition studies have utilized small-scale plots (1m2), though it has been shown that the area sampled can have significant impacts on the direction or magnitude of observed results. While a few studies have demonstrated scale-dependence in effects on species richness, I expand upon these findings by relating effects across scales to impacts on total community richness, community evenness, and spatial organization of vegetation. I find that nitrogen enrichment rarely produces large-scale species extirpation, but effects on evenness are nearly constant across sampling areas. While large-scale coexistence processes may facilitate species persistence at large spatial extents, fertilization also prompts increases in individual spatial aggregation, which may produce species extirpation in the long term. In Chapter 3, I evaluate changes in California grassland community composition in response to interannual variation in temperature and precipitation. In Mediterranean systems, the quantity and timing of rainfall is hypothesized to control turnover between distinct species groups. A key challenge to the evaluation of these species-climate relationships, however, is historical contingency in vegetation composition - non-independence between species abundances in a given year and the year previous, caused by local seed pools, plant-soil feedbacks, and other priority effects. To quantify how climate and prior community composition interact, I employ a novel application of multi-state modeling to a long-term dataset. This approach expands on traditional methods, which qualitatively describe variation among a priori species groups, to directly quantify the number of discrete vegetation states within a system and the probability of transition between them. When applied to ten years of community observation across a range of climatic conditions, this method produced a revised partitioning of vegetation states: one "classic" species group was split into two separate states based on performance under extreme drought. In turn, climate patterns interacted with the emergent properties of each vegetation state to control which community types were most likely to dominate. Invasive species, for example, were unlikely to persist under drought; yet low precipitation only tended to favor vegetation transitions to a native dominated state when these species were previously seeded. It is increasingly understood that integration across interacting sets of processes is needed to effectively understand the effects of global change on the diversity and composition of plant communities. Together, these three chapters highlight how local environmental characteristics, the scale of observation, and prior vegetation type combine to structure grassland responses to environmental changes. In doing so, my work contributes to a more complete understanding of ecological dynamics that is needed to better conserve and manage ecosystems in a rapidly changing world.

Download or read book The Effects of Interannual Precipitation Variability on the Functioning of Grasslands written by Laureano Gherardi Arbizu and published by . This book was released on 2014 with total page 151 pages. Available in PDF, EPUB and Kindle. Book excerpt: Climate change will result not only in changes in the mean state of climate but also on changes in variability. However, most studies of the impact of climate change on ecosystems have focused on the effect of changes in the central tendency. The broadest objective of this thesis was to assess the effects of increased interannual precipitation variation on ecosystem functioning in grasslands. In order to address this objective, I used a combination of field experimentation and data synthesis. Precipitation manipulations on the field experiments were carried out using an automated rainfall manipulation system developed as part of this dissertation. Aboveground net primary production responses were monitored during five years. Increased precipitation coefficient of variation decreased primary production regardless of the effect of precipitation amount. Perennial-grass productivity significantly decreased while shrub productivity increased as a result of enhanced precipitation variance. Most interesting is that the effect of precipitation variability increased through time highlighting the existence of temporal lags in ecosystem response. Further, I investigated the effect of precipitation variation on functional diversity on the same experiment and found a positive response of diversity to increased interannual precipitation variance. Functional evenness showed a similar response resulting from large changes in plant-functional type relative abundance including decreased grass and increased shrub cover while functional richness showed non-significant response. Increased functional diversity ameliorated the direct negative effects of precipitation variation on ecosystem ANPP but did not control ecosystem stability where indirect effects through the dominant plant-functional type determined ecosystem stability. Analyses of 80 long-term data sets, where I aggregated annual productivity and precipitation data into five-year temporal windows, showed that precipitation variance had a significant effect on aboveground net primary production that is modulated by mean precipitation. Productivity increased with precipitation variation at sites where mean annual precipitation is less than 339 mm but decreased at sites where precipitation is higher than 339 mm. Mechanisms proposed to explain patterns include: differential ANPP response to precipitation among sites, contrasting legacy effects and soil water distribution. Finally, increased precipitation variance may impact global grasslands affecting plant-functional types in different ways that may lead to state changes, increased erosion and decreased stability that can in turn limit the services provided by these valuable ecosystems.

Download or read book Ecosystem Functioning in Restored Grassland as Influenced by Ecotypic Variation Precipitation and Biodiversity written by Kiersten Bergquist and published by . This book was released on 2020 with total page 94 pages. Available in PDF, EPUB and Kindle. Book excerpt: The restoration of degraded tallgrass prairies can mitigate climate change due to the carbon accrued during the development of grasslands. The focal species, dominant grass Andropogon gerardii, can assist the recovery of grassland ecosystem functioning. Climate, local adaptation, and biodiversity have been found to impact the accrual of carbon in grasslands. This study examined the difference in ecosystem functioning between ecotypes along a dry to mesic precipitation scale. The study site for this project was at the Southern Illinois University Agriculture Research Center in Carbondale, Illinois. The field site was planted with seeds originating from dry to mesic ecotypes, and the resulting ecosystem functioning was analyzed. It was found that the Kansas non-local ecotypes had significantly higher biodiversity, while the local Illinois sites demonstrated local adaptation with A. gerardii. Aboveground plant biomass was higher in the local sites, but there was no difference in carbon accrual between any of the ecotypes. While ecotypic variation in a dominant species will usually differentially influence ecosystem functioning, in this case, high biodiversity and local adaptation result in similar carbon inputs in grassland soil. It is necessary to analyze the carbon content of the soil in the drier field sites in order to determine if major differences in rainfall leads to differences in carbon accrual. If the goal of restoring a tallgrass prairie in southern Illinois is to assist with climate change mitigation, then it does not make a significant difference if the dominant species is sourced locally or non-locally.

Download or read book Climate Vulnerability written by and published by Elsevier. This book was released on 2013-03-15 with total page 1086 pages. Available in PDF, EPUB and Kindle. Book excerpt: Climate change has been the subject of thousands of books and magazines, scientific journals, and newspaper articles daily. It’s a subject that can be very political and emotional, often blurring the lines between fact and fiction. The vast majority of research, studies, projections and recommendations tend to focus on the human influence on climate change and global warming as the result of CO2 emissions, often to the exclusion of other threats that include population growth and the stress placed on energy sources due to emerging global affluence. Climate Vulnerability, Five Volume Set seeks to strip away the politics and emotion that surround climate change and will assess the broad range of threats using the bottom up approach—including CO2 emissions, population growth, emerging affluence, and many others—to our five most critical resources: water, food, ecosystems, energy, and human health. Inclusively determining what these threats are while seeking preventive measures and adaptations is at the heart of this unique reference work. Takes a Bottom-Up approach, addressing climate change and the threat to our key resources at the local level first and globally second, providing a more accurate and inclusive approach. Includes extensive cross-referencing, which is key to readers as new connections between factors can be discovered. Cuts across a number of disciplines and will appeal to Biological Science, Earth & Environmental Science, Ecology, and Social Science, comprehensively addressing climate change and other threats to our key resources from multiple perspectives

Download or read book Climate Change Adaptation and Mitigation Management Options written by James M. Vose and published by CRC Press. This book was released on 2013-12-05 with total page 494 pages. Available in PDF, EPUB and Kindle. Book excerpt: Forest land managers face the challenges of preparing their forests for the impacts of climate change. However, climate change adds a new dimension to the task of developing and testing science-based management options to deal with the effects of stressors on forest ecosystems in the southern United States. The large spatial scale and complex interactions make traditional experimental approaches difficult. Yet, the current progression of climate change science offers new insights from recent syntheses, models, and experiments, providing enough information to start planning now for a future that will likely include an increase in disturbances and rapid changes in forest conditions. Climate Change Adaptation and Mitigation Management Options: A Guide for Natural Resource Managers in Southern Forest Ecosystems provides a comprehensive analysis of forest management options to guide natural resource management in the face of future climate change. Topics include potential climate change impacts on wildfire, insects, diseases, and invasives, and how these in turn might affect the values of southern forests that include timber, fiber, and carbon; water quality and quantity; species and habitats; and recreation. The book also considers southern forest carbon sequestration, vulnerability to biological threats, and migration of native tree populations due to climate change. This book utilizes the most relevant science and brings together science experts and land managers from various disciplines and regions throughout the south to combine science, models, and on-the-ground experience to develop management options. Providing a link between current management actions and future management options that would anticipate a changing climate, the authors hope to ensure a broader range of options for managing southern forests and protecting their values in the future.

Download or read book Grasslands and Climate Change written by David J. Gibson and published by Cambridge University Press. This book was released on 2019-03-21 with total page 363 pages. Available in PDF, EPUB and Kindle. Book excerpt: A comprehensive assessment of the effects of climate change on global grasslands and the mitigating role that ecologists can play.

Download or read book PRAIRIEMAP a GIS Database for Prairie Grassland Management in Western North America written by and published by . This book was released on 2003 with total page 6 pages. Available in PDF, EPUB and Kindle. Book excerpt: The PRAIRIEMAP web site (http://prairiemap.wr.usgs.gov) contains links to partners, documentation of the data, and a directory of GIS data that can be downloaded.

Download or read book Fire Effects Guide written by and published by . This book was released on 1994 with total page 282 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Causes and Consequences of Species Diversity in Forest Ecosystems written by Aaron M. Ellison and published by MDPI. This book was released on 2019-07-30 with total page 274 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book is a printed edition of the Special Issue Causes and Consequences of Species Diversity in Forest Ecosystems that was published in Forests

Download or read book Global Rangelands written by A. C. Grice and published by CABI. This book was released on 2002-07-29 with total page 320 pages. Available in PDF, EPUB and Kindle. Book excerpt: Although traditionally defined as areas where natural vegetation is exploited for grazing by domestic and native herbivores, rangelands are used by many different people, for a host of purposes. As well as livestock products, rangelands provide fuels, minerals and water and are used for ecotourism, recreation, nature conservation and as carbon sinks. More than half of the earth's land surface is rangeland and millions of people, both within and outside the rangelands, depend on them. This book addresses the important issues confronting the rangelands and presents new concepts and approaches for the management of rangeland resources. It is relevant to the people who live in or depend on the rangelands, and to the institutions and organisations that support them.

Download or read book Climate Change and Canada s Forests written by T. B. Williamson and published by . This book was released on 2009 with total page 108 pages. Available in PDF, EPUB and Kindle. Book excerpt: Forest managers can expect the unexpected and they can expect that change will be ongoing and unrelenting. Some general recommendations for beginning to address climate change in Canada's forest sector include enhancing the capacity to undertake integrated assessment of vulnerabilities to climate change at various scales; increasing resources to monitor the impacts of climate change; increasing resources for impacts and adaptation science; reviewing forest policies, forest planning, forest management approaches, and institutions to assess our ability to achieve social objectives under climate change; embedding principles of risk management and adaptive management into forest management; and maintaining or improving the capacity for communicating, networking, and information sharing with the Canadian public and within the forest sector."--Pub. website.

Download or read book Wildland Fire in Ecosystems written by and published by . This book was released on 2000 with total page 92 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Phenological Research written by Irene L. Hudson and published by Springer Science & Business Media. This book was released on 2009-11-24 with total page 525 pages. Available in PDF, EPUB and Kindle. Book excerpt: As climate change continues to dominate the international environmental agenda, phenology – the study of the timing of recurring biological events – has received increasing research attention, leading to an emerging consensus that phenology can be viewed as an ‘early warning system’ for climate change impact. A multidisciplinary science involving many branches of ecology, geography and remote sensing, phenology to date has lacked a coherent methodological text. This new synthesis, including contributions from many of the world’s leading phenologists, therefore fills a critical gap in the current biological literature. Providing critiques of current methods, as well as detailing novel and emerging methodologies, the book, with its extensive suite of references, provides readers with an understanding of both the theoretical basis and the potential applications required to adopt and adapt new analytical and design methods. An invaluable source book for researchers and students in ecology and climate change science, the book also provides a useful reference for practitioners in a range of sectors, including human health, fisheries, forestry, agriculture and natural resource management.

Download or read book High Mountain Conservation in a Changing World written by Jordi Catalan and published by Springer. This book was released on 2017-08-03 with total page 413 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book provides case studies and general views of the main processes involved in the ecosystem shifts occurring in the high mountains and analyses the implications for nature conservation. Case studies from the Pyrenees are preponderant, with a comprehensive set of mountain ranges surrounded by highly populated lowland areas also being considered. The introductory and closing chapters will summarise the main challenges that nature conservation may face in mountain areas under the environmental shifting conditions. Further chapters put forward approaches from environmental geography, functional ecology, biogeography, and paleoenvironmental reconstructions. Organisms from microbes to large carnivores, and ecosystems from lakes to forest will be considered. This interdisciplinary book will appeal to researchers in mountain ecosystems, students and nature professionals. This book is open access under a CC BY license.