Download or read book The Effects of Temporal Variation in Precipitation on Plant Coexistence in an Annual Grassland Community written by Mary N. Van Dyke and published by . This book was released on 2023 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: This dissertation aims to contribute to our understanding of plant coexistence and explore how global change could disrupt these dynamics thus altering the composition of future communities. I have attempted to answer these broad ecological questions by studying the coexistence mechanisms operating in an annual grassland in coastal southern California that experiences high interannual variability in climate, particularly in precipitation. I have explored multiple mechanisms of coexistence operating in the community and the physiological bases of the interacting plant species to make my results more broadly applicable. Each chapter also discusses how the results can inform our predictions about how plant communities will continue to respond to global change. Chapter one explores how interactions between neighboring species are altered by changes in rainfall. Precipitation patterns have long been known to shape plant distributions but how changes in these patterns effect species interactions and thus community composition is less understood. As precipitation patterns across the globe are altered by global change, understanding how interactions like competition between plants is impacted will help us anticipate potential community composition changes. We studied how changes in precipitation altered competitive dynamics by studying the direct effects of changes on individual species, as well as, by the changing strength of competitive interactions between species. We grew six annual species under two rainfall conditions with varying densities and identities of competitors. We parameterized a population growth model that allowed us to determine stabilizing niche differences and fitness differences between species pairs which determine their ability to coexist. We found that reduced precipitation had little direct impact on species grown alone, but it qualitatively shifted predicted competitive outcomes for 10 of 15 species pairs. We also found that species that were more similar in their functional traits were less likely to experience changes in their competitive outcomes than species that were less similar. In chapter 2, we investigated the mechanism that might be driving the changes in species competitive interactions that we found with changes in precipitation. We hypothesized that species flowering phenology (timing) might contribute to species ability to coexist by separating resource intensive periods for species over the growing season. These critical temporal dynamics could be disturbed if changes in precipitation affect the flowering phenology of some species and not others. We found that changes in rainfall shift some species flowering phenology, but sensitivity differed among neighboring species. Four of seven species we studied started and/or peaked flowering earlier in response to reduced water availability. The idiosyncratic responses among neighboring species has the potential to disrupt temporal coexistence mechanisms because it alters the flowering overlap between species pairs. We found the species pairs whose competitive interactions changed in the experiment described in chapter one had larger differences in their phenological responses to reduced rainfall than pairs whose competitive outcomes did not change. This shows that species pairs whose flowering time overlap changed more, were more likely to experience a change in their competitive interaction. Therefore, current temporal spacing between peak flowering times likely contributes to coexistence in the community and if changes in rainfall disrupt this, species may lose their ability to coexist, altering the composition of the community. Chapter 3 explores coexistence at a broader timescale and investigates how multiple mechanisms of coexistence operate simultaneously. Southern coastal California experiences high interannual variation in rainfall. Modern coexistence theory suggests that coexistence mechanisms, such as the temporal storage effect, may be important in communities experiencing fluctuating abiotic conditions. To examine the effects of temporal variation in abiotic conditions on coexistence, we studied an annual grassland community that experiences high interannual variation in precipitation. We found that species demographic rates from the last 15 years, including germination rate and low-density fecundity, are rarely strongly positively correlated with other species in the community, indicating that species differ in which years they perform best, and therefore likely specialize on distinct abiotic conditions. Variation in response to interannual differences in rainfall concentrates intraspecific interactions relative to interspecific interactions and favors coexistence. Additionally, we found that species differences in functional traits, especially rooting depth, water use efficiency, and leaf nitrogen were well correlated with differences in species demographic responses, such that species with similar traits did best in the same years. Taken together this deepens our understanding of coexistence in the community and provides greater context for how plant communities may respond to future increases in climatic variability.
Download or read book Mechanisms for Species Coexistence Under Environmental Change written by Loralee Larios and published by . This book was released on 2013 with total page 102 pages. Available in PDF, EPUB and Kindle. Book excerpt: Understanding the potential mechanisms that influence invasion resistance and coexistence in plant communities has been a central tenet of invasion ecological research during the past few decades. My dissertation used observational and experimental approaches to understand what processes influence whether a community is invaded, resists invasion, or results in species coexistence within a California grassland. Chapter 2 reviewed the impacts that alien plant species may have on communities and provided a framework for how to identify when invader impacts lead to recovery constraints for the native community and integrate these constraints into restoration efforts. Chapter 3 investigated how species effects on resource availability can result in differing invasion dynamics in native versus exotic dominated grasslands. I found that while exotic and native species differentially alter the availability of light and nitrogen in a community, nitrogen availability is key in determining invasion of an exotic into a native grassland as well as the invasion of a native into an exotic dominated community. Chapter 4 investigated how propagule pressure after an extreme disturbance can result in the invasion of intact native grasslands. I found that the recovery of native grassland stands after an extreme disturbance (fire+drought) can be stalled by an influx of exotic propagules from the surrounding matrix. Chapter 5 addressed how the strength of plant-soil feedbacks for a native and exotic may change with soil resource availability changes on soil communities and with a competitor. I found a negative effect of exotic conditioned soil on native growth and no effect of native conditioned soil on exotic growth, suggesting that plant-soil feedbacks may facilitate the establishment of the exotic as well as its dominance. Lastly, Chapter 6 investigated how seed addition and soil amendments management efforts affected native recovery after an extreme disturbance. I found that seed additions and soil N reductions were able to increase the establishment and fitness of some natives, but may not be sufficient to promote full native recovery. This work provides a tool to understand not only why native resident communities are invaded but also how to reduce the resistance of invaded communities and increase the resistance of native communities. Additionally this work allowed me to integrate the impacts that exotic species have on communities to make general predictions about the recovery of native communities after an extreme disturbance or control efforts. Overall, I observed that native communities and populations are vulnerable to invasion after a large disturbance and with nitrogen enrichment. From low to moderate nitrogen availability, native and exotic species should coexist due to niche partitioning, but not as a result of density dependent negative plant-soil feedbacks. Lastly, I found that an exotic species is able to maintain its dominance due to its strong competitive effect on native species, particularly at high nitrogen availability and its ability to culture a soil community that negatively impacts the growth of native species.
Download or read book Progress in Botany written by Joachim W. Kadereit and published by Springer Science & Business Media. This book was released on 2013-11-11 with total page 562 pages. Available in PDF, EPUB and Kindle. Book excerpt: With one volume each year, this series keeps scientists and advanced students informed of the latest developments and results in all areas of the plant sciences. The present volume includes reviews on genetics, cell biology, and vegetation science.
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 Temporal Variation and Plant Community Regeneration After Disturbance written by Chhaya Megan Werner and published by . This book was released on 2018 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Plant communities exist in a variable world. Community regeneration after disturbance can depend strongly on initial conditions, with long-term consequences. This dissertation investigates the importance of initial conditions, and in particular inter-annual weather variation, on community regeneration. Chapter 1 demonstrates the persistence of initial differences in community composition, through priority of seed arrival in a grassland restoration experiment. For Chapter 2, I conducted a manipulative experiment in burned mixed-conifer forest to test the multiway interaction of direct and competition-mediated effects of climate change on vegetation dynamics. I used two approaches to studying climate change: a manipulation of climate, and multiple years of initiation, and found the effects of both climate treatments were profound and distinct, and also contingent upon biotic factors (shrub competition) and species-level differences. In Chapter 3, I studied regeneration after two chaparral fires, one of which burned after a severe multi-year drought. The results indicated that pre-fire drought can have negative effects on post-fire regeneration of shrubs and may increase the window of time during which herbaceous cover is high. Taken together, this thesis is a multi-ecosystem investigation of the role of stochastic factors in plant community regeneration, with a focus on how present variation can be used to predict the consequences of future global change.
Download or read book Plant Diversity and Distribution Patterns in Serpentine Grasslands written by Sarah Claire Elmendorf and published by . This book was released on 2008 with total page 228 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book The Nature of Plant Communities written by J. Bastow Wilson and published by Cambridge University Press. This book was released on 2019-03-21 with total page 373 pages. Available in PDF, EPUB and Kindle. Book excerpt: Provides a comprehensive review of the role of species interactions in the process of plant community assembly.
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 Serpentine written by Susan Patricia Harrison and published by Univ of California Press. This book was released on 2011-02-02 with total page 460 pages. Available in PDF, EPUB and Kindle. Book excerpt: "This outstanding volume brings together leading experts across a broad range of disciplines to bring serpentine into focus, as never before, as a window to understanding major natural processes and patterns in nature. By doing so, the authors illuminate exciting questions and challenges that will serve to inspire and direct much future study of these fascinating systems."—Bruce G. Baldwin, University of California, Berkeley
Download or read book Compettition and Coexistence in a California Annual Serpentine Grassland written by Heather L. Reynolds and published by . This book was released on 1995 with total page 264 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Long term Effects of Climate Change on Grassland Soil Systems written by Steven Charles Jr Rostkowski and published by . This book was released on 2011 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Climate change predictions for the Great Plains region of North America include increased temperatures, changes to annual precipitation, and reduced growing season precipitation, which will likely alter grassland soil systems. To date, few studies have examined belowground community responses to predicted climate change scenarios, with fewer assessing long-term changes. My research focused on the impacts of long-term changes in precipitation and associated soil water content on belowground grassland systems (belowground plant biomass, soil carbon (C) and nitrogen (N) pools, microbial biomass C and N, and invertebrate communities) using recently collected samples from a long-term (16-yr) reciprocal core transplant between Konza Prairie Biological Station (MAP = 850 mm) and Kansas State Agricultural Research Center at Hays (MAP = 580 mm), with the Hays site having a long-term average annual precipitation amount that is ~30% less than the Konza site. Results from the experiment indicate that either increases or decreases in annual precipitation can have profound effects on belowground grassland systems. Belowground plant biomass, microbial biomass, and potential C mineralization rates were greater at the wetter Konza site regardless of soil origin. Total C stored in soils incubated at Konza was significantly greater as well, likely due to greater root inputs. The effects of precipitation were most apparent in the surface soil layers (0-20 cm), while soil origin impacted soil properties to a greater extent with increasing depth. This contrasted with results for the soil mesofauna, where total microarthropods responded negatively and nematodes responded positively to increased annual precipitation. Results of this study indicate important changes in soil C and N pools, belowground plant biomass, and soil mesofauna within grassland systems subject to changing precipitation regimes, and suggest more mesic prairie systems are more sensitive to changes in soil water availability than those in more arid grassland systems.
Download or read book Israel Journal of Plant Sciences written by and published by . This book was released on 2007 with total page 388 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Encyclopedia of Ecology written by Brian D. Fath and published by Elsevier. This book was released on 2018-08-23 with total page 2786 pages. Available in PDF, EPUB and Kindle. Book excerpt: Encyclopedia of Ecology, Second Edition, Four Volume Set continues the acclaimed work of the previous edition published in 2008. It covers all scales of biological organization, from organisms, to populations, to communities and ecosystems. Laboratory, field, simulation modelling, and theoretical approaches are presented to show how living systems sustain structure and function in space and time. New areas of focus include micro- and macro scales, molecular and genetic ecology, and global ecology (e.g., climate change, earth transformations, ecosystem services, and the food-water-energy nexus) are included. In addition, new, international experts in ecology contribute on a variety of topics. Offers the most broad-ranging and comprehensive resource available in the field of ecology Provides foundational content and suggests further reading Incorporates the expertise of over 500 outstanding investigators in the field of ecology, including top young scientists with both research and teaching experience Includes multimedia resources, such as an Interactive Map Viewer and links to a CSDMS (Community Surface Dynamics Modeling System), an open-source platform for modelers to share and link models dealing with earth system processes
Download or read book Grassland structure and function written by L.F. Huenneke and published by Springer. This book was released on 1990-03-14 with total page 222 pages. Available in PDF, EPUB and Kindle. Book excerpt: The chapters in this volume are based on a opportumtles for studying the links between symposium, "California grasslands: structure abiotic and biotic components. and productivity", supported by the National The contributions in this volume illustrate Science Foundation. The primary objective of the links between population-level processes this symposium was to integrate the current and system-level phenomena in a well-studied understanding of controls on ecosystem struc community. Unfortunately, some areas of cur ture and function with the approaches of popu rent research (e.g., nutrient cycling) are under lation biology. The annual grasslands are represented in this volume. For other topics eminently suitable for experimental and manip (particularly the role of invertebrate con sumers), the lack of data from the annual grass ulative studies of ecosystem processes. The short lives and small stature of the component land brought a broader grassland perspective. plant species make experimental work far more Together, however, the contributions illustrate practical than in forests or even in perennial the importance of different ecological ap dominated prairies. The system's small-scale proaches in studying the controls on structure patchiness, and the obvious importance of and function of a complex system. the region's mediterranean climate in the life cycle of the annual vegetation, afford many L.F. Huenneke and H.A. Mooney Huenneke, L.F. and Mooney, H. (eds) Grassland Structure and Function: California Annual Grassland.
Download or read book Proceedings of the National Academy of Sciences of the United States of America written by National Academy of Sciences (U.S.). and published by . This book was released on 2006 with total page 1328 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Terrestrial Ecosystems in a Changing World written by Josep G. Canadell and published by Springer Science & Business Media. This book was released on 2007-01-10 with total page 344 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book examines the impacts of global change on terrestrial ecosystems. Emphasis is placed on impacts of atmospheric, climate and land use change, and the book discusses the future challenges and the scientific frameworks to address them. Finally, the book explores fundamental new research developments and the need for stronger integration of natural and human dimensions in addressing the challenge of global change.
