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Effects Of Nitrogen Additions And Exotic Grasses On Nitrogen Cycling And Microbial Communities In Coastal Sage Scrub Soil
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Book Synopsis Effects of Nitrogen Additions and Exotic Grasses on Nitrogen Cycling and Microbial Communities in Coastal Sage Scrub Soil by : Francy S. El Souki
Download or read book Effects of Nitrogen Additions and Exotic Grasses on Nitrogen Cycling and Microbial Communities in Coastal Sage Scrub Soil written by Francy S. El Souki and published by . This book was released on 2007 with total page 118 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Ecological Impacts of Nitrogen Deposition, Drought and Nonnative Plant Invasion on Coastal Sage Scrub of the Santa Monica Mountains by : Justin Michael Valliere
Download or read book Ecological Impacts of Nitrogen Deposition, Drought and Nonnative Plant Invasion on Coastal Sage Scrub of the Santa Monica Mountains written by Justin Michael Valliere and published by . This book was released on 2016 with total page 201 pages. Available in PDF, EPUB and Kindle. Book excerpt: Multiple drivers of global environmental change increasingly threaten native ecosystems, including atmospheric pollution and resulting changes in climate and nutrient cycling, and the globalization of species. These factors may also have complex and interactive ecological effects. Nitrogen (N) deposition, the input of reactive N from the atmosphere to the earth's surface, is increasing dramatically worldwide due to anthropogenic air pollution, with the potential to negatively impact terrestrial plant diversity. Elevated N deposition may also interact with other drivers of environmental change, for example by promoting the invasion of nonnative plant species, or increasing plant susceptibility to drought or other secondary stressors. Perhaps nowhere in the U.S. is this of more immediate environmental concern than in southern California, which is a global hotspot of biodiversity and one of the most air-polluted and populous parts of the country. High levels of N deposition have been implicated in the widespread conversion of coastal sage scrub (CSS) to annual grasslands dominated by nonnative grasses and forbs. The Santa Monica Mountains National Recreation Area of southern California protects a substantial area of remaining CSS, but due to the park's proximity to the City of Los Angeles, stands of CSS nearest urban areas may be subject to high levels of N deposition. The state of California is also in the midst of a record-breaking drought, beginning in 2011, and this may exacerbate the negative impacts of N deposition and nonnative plant species. The objective of this work is to explore the effects of N deposition, drought and nonnative plant invasion on CSS of the Santa Monica Mountains at multiple ecologically relevant scales. I explored relationships of atmospheric N pollution and N deposition with native plant richness and cover of nonnative species at the landscape level, finding N deposition reduces richness of native herbaceous species and is associated with higher nonnative cover. I also investigated the impact of multiple realistic levels of N addition on CSS in a field fertilization experiment on the low end of the N deposition gradient during a period that coincided with the California drought. Through this experiment, I demonstrated increased N availability may reduce water-use efficiency and drought tolerance of native shrubs, resulting in increased dieback, while concomitantly favoring nonnative annual species. Finally, I explored the role of the soil microbial community in mediating impacts of these factors on native and nonnative plant species, finding that N-impacted soil communities may provide less protection against drought in native shrub seedlings and increase growth of invasive plant species. Collectively, these results illustrate the significant ecological threat of increased N deposition on the severely threatened CSS of southern California, and potential interactions with other drivers of global change such as extreme drought, and nonnative plant invasion.
Book Synopsis Effects of Moisture, Nitrogen, and Herbicide Application on the Relationship Between an Invasive Grass and a Rare Coastal Sage Scrub Species: Acanthomintha Ilicifolia by :
Download or read book Effects of Moisture, Nitrogen, and Herbicide Application on the Relationship Between an Invasive Grass and a Rare Coastal Sage Scrub Species: Acanthomintha Ilicifolia written by and published by . This book was released on 2017 with total page 91 pages. Available in PDF, EPUB and Kindle. Book excerpt: Nitrogen deposition and precipitation variability can have large effects on the structure and composition of Coastal Sage Scrub communities. These can occur as direct responses to changes in resource availability or indirectly through shifts in the competitive relationships among the many native and non-native plant species. These interactions can influence phenology, limit species distributions, and may play a role in the extinction risk of rare plants. There have been studies on how resources impact invasive species in Coastal Sage Scrub but few have focused on the impacts of invasive grasses on rare, endemic native forbs. I conducted a greenhouse study of the effects of nitrogen and moisture on the relationship between Acanthomintha ilicifolia (a rare native forb) and an invasive grass Brachypodium distachyon. I employed a 3-way factorial design using three moisture levels, three nitrogen treatments, and the application of a selective herbicide used to manage Brachypodium distachyon. Multiple metrics were used to assess the impact of the treatments including aboveground biomass, flower production and timing, leaf size, and chemical composition. For both species, inter and intraspecific competition limited vegetative growth and competitor densities was often more important than the identity of the competitor. We observed weak nitrogen addition effects, likely due to unexpectedly high levels of nitrogen in the natural soil used in the experiment. Total amount of water was not an important factor in this experiment. This could be the result of the relatively mild conditions in the greenhouse or because our experiment could not mimic other stressors like extreme variability in soil moisture and large changes in temperature and insolation. Finally, herbicide treatment was effective at controlling Brachypodium distachyon however significant delays in growth and flowering of Acanthomintha ilicifolia were observed. Herbicide treatment also appeared to alter soil nitrogen relationships. These observed changes in phenology of the endangered species and belowground soil processes need to be considered prior to its continued and wide-spread use in conservation management. Although it can be difficult to extrapolate the results of greenhouse experiments to the field, our results have significant implications for current management practices and warrant further research.
Book Synopsis Ecosystems of California by : Harold Mooney
Download or read book Ecosystems of California written by Harold Mooney and published by Univ of California Press. This book was released on 2016-01-19 with total page 1009 pages. Available in PDF, EPUB and Kindle. Book excerpt: This long-anticipated reference and sourcebook for California’s remarkable ecological abundance provides an integrated assessment of each major ecosystem type—its distribution, structure, function, and management. A comprehensive synthesis of our knowledge about this biologically diverse state, Ecosystems of California covers the state from oceans to mountaintops using multiple lenses: past and present, flora and fauna, aquatic and terrestrial, natural and managed. Each chapter evaluates natural processes for a specific ecosystem, describes drivers of change, and discusses how that ecosystem may be altered in the future. This book also explores the drivers of California’s ecological patterns and the history of the state’s various ecosystems, outlining how the challenges of climate change and invasive species and opportunities for regulation and stewardship could potentially affect the state’s ecosystems. The text explicitly incorporates both human impacts and conservation and restoration efforts and shows how ecosystems support human well-being. Edited by two esteemed ecosystem ecologists and with overviews by leading experts on each ecosystem, this definitive work will be indispensable for natural resource management and conservation professionals as well as for undergraduate or graduate students of California’s environment and curious naturalists.
Book Synopsis Soil Ecology and Ecosystem Services by : Diana H. Wall
Download or read book Soil Ecology and Ecosystem Services written by Diana H. Wall and published by . This book was released on 2013-07-18 with total page 422 pages. Available in PDF, EPUB and Kindle. Book excerpt: This multi-contributor, international volume synthesizes contributions from the world's leading soil scientists and ecologists, describing cutting-edge research that provides a basis for the maintenance of soil health and sustainability. The book covers these advances from a unique perspective of examining the ecosystem services produced by soil biota across different scales - from biotic interactions at microscales to communities functioning at regional and global scales. The book leads the user towards an understanding of how the sustainability of soils, biodiversity, and ecosystem services can be maintained and how humans, other animals, and ecosystems are dependent on living soils and ecosystem services. This is a valuable reference book for academic libraries and professional ecologists worldwide as a statement of progress in the broad field of soil ecology. It will also be of interest to both upper level undergraduate and graduate students taking courses in soil ecology, as well as academic researchers and professionals in the field requiring an authoritative, balanced, and up-to-date overview of this fast expanding topic.
Book Synopsis Resource Partitioning in Invasive Annuals, Native Shrubs and Native Grasses in California by :
Download or read book Resource Partitioning in Invasive Annuals, Native Shrubs and Native Grasses in California written by and published by . This book was released on 2013 with total page 121 pages. Available in PDF, EPUB and Kindle. Book excerpt: The spread of invasive species into natural, native habitats threatens the species diversity and function of many ecosystems globally, and locally. In California the past and future expansion of invasive annual plants is linked to human disturbance and climate change. The invasive annuals differ from native plants in growth form and phenology. Understanding how these differences impact resource dynamics in invaded ecosystems is important for predicting the response of these ecosystems to future climate change. In this dissertation I focused on three aspects of resource dynamics. The carbon (C) cycle and how soil respiration differs between invasive annuals and native coastal sage scrub species; the nitrogen (N) cycle and how altered rainfall patterns mediate N availability and partitioning between invasive annuals, native shrubs and microbes; seed production of two native grasses and how competition from invasive annuals affects their contribution to a future seed bank. In chapter 1, I evaluated how soil respiration (Rs), a critical component of ecosystem carbon (C) storage, differs between native shrubs and inter-shrub patches dominated by invasive annuals. Rs can be partitioned into a root associated, autotrophic component (Ra) and a microbial, heterotrophic component (Rh). Discriminating between Ra and Rh provides insight into the underlying mechanisms which determine seasonal patterns in Rs. I found that phenology played an important role in the difference between invaded and shrub areas. Rs was 40% higher in invaded areas, primarily due to higher Ra early in the season. Overall the shrubs had a shorter respiration season due to more constrained phenology and contributed less C loss to the atmosphere. In invaded areas higher respiration rates were in part due to higher temperature tolerance of Ra and Rh. This suggests that water is more limiting than temperature in invaded areas. If, as expected, rainfall patterns shift in the future then C losses may be even higher from invaded areas. In chapter 2, I experimentally manipulated seasonal rainfall totals and determined the effect on nitrogen (N) partitioning between invasive annuals, a native shrub and the microbial community. Microbes, invasive annuals and native shrubs all competed for early season N, but allocation patterns differed dramatically. Microbes took up N rapidly and turned it over to soil organic matter where the N was stable for the whole growing season. Invasive annuals also allocated N rapidly. Shrubs on the other hand had a mechanism for N storage allowing them to take up N early, when it was available, but allocate it later when they needed it for new leaf growth. Overall the effects of altered rainfall were small. Dry conditions caused slower microbial N turnover early in the season and lower total biomass by the end of the season. At the end of the season N storage differed between invasives and natives. Native shrubs have a conservative nutrient retention strategy and resorbed much of the N from their leaves. In contrast the invasives died and N stayed in the dead leaf litter. When leaf litter decomposes in the following growing season, N becomes available again for uptake. Invasives are able to take advantage of excess N, when it is available, so leaf litter N inputs may benefit invasives in the next growing season. Invasive annual grasses compete more directly with native grasses than with native shrubs, because they have more similar resource demands. In chapter 3, I compared seed production of two native grasses grown in the absence and in the presence of invasive annual competitors. Native abundance was much lower in plots with invasive annuals and therefore seed production for a given area was suppressed in the presence of invasive annuals. However, seed production per unit plant biomass, was higher in the presence of invasives. This indicates that more resources were allocated to reproduction in the environment with invasive competitors. Furthermore, there were no adverse effects on seed quality and in one case seeds taken from plots with invasive competitors produced higher biomass than seeds grown without invasive competitors. Higher seedling biomass could confer an advantage when germinating among other competitors. Together these results indicate that different invasive phenology affects C and N cycling. These differences are particularly pronounced early and late in the growing season. Both the C and N cycle are more rapid and less conserved in invaded areas compared to shrub areas. In the case of C this has important implications for feedbacks to regional and global climate change. In the case of N, it has implications for ecosystem N retention and the possibility to further promote invasion. The evidence I found for early N uptake by shrubs and higher investment to reproductive allocation by native grasses, suggests that natives have resource use strategies which may allow them to evade invasive competition, and persist despite strong invasive pressure.
Book Synopsis The European Nitrogen Assessment by : Mark A. Sutton
Download or read book The European Nitrogen Assessment written by Mark A. Sutton and published by Cambridge University Press. This book was released on 2011-04-14 with total page 665 pages. Available in PDF, EPUB and Kindle. Book excerpt: Presenting the first continental-scale assessment of reactive nitrogen in the environment, this book sets the related environmental problems in context by providing a multidisciplinary introduction to the nitrogen cycle processes. Issues of upscaling from farm plot and city to national and continental scales are addressed in detail with emphasis on opportunities for better management at local to global levels. The five key societal threats posed by reactive nitrogen are assessed, providing a framework for joined-up management of the nitrogen cycle in Europe, including the first cost-benefit analysis for different reactive nitrogen forms and future scenarios. Incorporating comprehensive maps, a handy technical synopsis and a summary for policy makers, this landmark volume is an essential reference for academic researchers across a wide range of disciplines, as well as stakeholders and policy makers. It is also a valuable tool in communicating the key environmental issues and future challenges to the wider public.
Book Synopsis The Effects of Anthropogenic Nitrogen Deposition on the Gas Exchange, Specific Leaf Area, and Leaf Nitrogen Concentration of Southern California Coastal Sage Scrub and Chaparral Shrubs by : Kimberly Ann Davis
Download or read book The Effects of Anthropogenic Nitrogen Deposition on the Gas Exchange, Specific Leaf Area, and Leaf Nitrogen Concentration of Southern California Coastal Sage Scrub and Chaparral Shrubs written by Kimberly Ann Davis and published by . This book was released on 2008 with total page 98 pages. Available in PDF, EPUB and Kindle. Book excerpt: The semi-arid shrublands of Southern California are subject to some of the highest rates of atmospheric nitrogen deposition in North America. Little is known about the effects of nitrogen (N) pollution on drought-deciduous coastal sage scrub species (CSS) such as California sage (Artemisia californica) and black sage (Salvia mellifera), and sclerophyllous chamise chaparral species such as chamise (Adenostoma fasciculatum) that inhabit this region. This study monitored the photosynthetic and respiration rates, leaf conductance, leaf nitrogen content and specific leaf area of these species quarterly over the course of two years in a mature CSS stand and a pre-and post-fire chaparral stand. An in-situ experiment was conducted; half of the 10 X 10 meter study plots at each site were subjected to an additional 50 kg N ha-1 in the form of NH4N03 fertilizer in October of 2003 and 2004. The remaining plots served as controls subject to ambient N deposition. Rainfall dependent seasonal changes of these physiological measures that are typical of Mediterranean-type ecosystems were observed, however a multiple analysis of variance (MANOVA) indicates that there were no significant differences between control and experimental plots due to N addition. This may be due to the temporal asynchrony of the artificial nitrogen addition and seasonal rainfall, as the nitrogen was added in the fall when the shrubs are physiologically dormant (CSS) or minimal (CC). The first rains may have flushed the N into downslope streams, away from the rooting zones of the shrubs. Alternatively, the lack of significant differences may be because the shrubs had been engaging in luxury consumption, or were already existing in a state of N saturation. Key words: Adenostoma fasciculatum, Artemisia californica, Salvia mellifera, coastal sage scrub, chaparral, nitrogen deposition.
Book Synopsis Dissertation Abstracts International by :
Download or read book Dissertation Abstracts International written by and published by . This book was released on 2005 with total page 794 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Sugar Application and Nitrogen Pools in Wyoming Big Sagebrush Communities and Exotic Annual Grasslands by : Dana L. Witwicki
Download or read book Sugar Application and Nitrogen Pools in Wyoming Big Sagebrush Communities and Exotic Annual Grasslands written by Dana L. Witwicki and published by . This book was released on 2005 with total page 118 pages. Available in PDF, EPUB and Kindle. Book excerpt: Within A rtemisia tridentata ssp. wyomingensis Nutt. (Wyoming big sagebrush) communities of the Great Basin, lands dominated by the exotic annual grass Bromus tectorum L. (cheatgrass) are increasing at an alarming rate. Carbon applications, which reduce plant-available soil N, have been suggested as a way to give native vegetation a competitive advantage over exotic annual grasses when reseeding after a fire. The main objectives of my study were to 1) compare N pools in intact A. tridentata- and B. tectorum-dominated communities to look for evidence of ecosystem changes associated with annual grass invasion, and 2) quantify and compare the effects of sugar and nitrogen additions on N pools in each of these communities. Research occurred at six sites in eastern Oregon and southwestern Idaho, each containing pairs of A. tridentata and exotic annual grass communities in close proximity. Pairs were carefully selected with similar soil types, precipitation, elevation, aspect, slope and ecological sites (i.e. potential vegetation and production). At the beginning of the cheatgrass growing season (late fall), three treatments (sugar, nitrogen or control) were applied. For soil pools, only one difference between untreated plots of annual and native communities was detected. In autumn. NO3 in the native community was about two-thirds the level in the annual community. The sugar treatment decreased inorganic N to near undetectable levels one week after application, and levels remained low six months later (during peak B. tectorum biomass). Although the sugar treatment did not increase microbial biomass N from chloroform fumigation extraction, we found higher '5N in microbial biomass and soil organic matter, suggesting that more N remained in the microbial pooi over the growing season. The reduction of aboveground plant biomass by sugar and the increase of aboveground plant biomass from nitrogen addition were more pronounced for B. tectorum than for native plants. Plant responses indicated that treatment with labile carbon like sugar may be useful tools for restoration of native plants and for prevention of B. tectorum dominance, but additional research is necessary to quantify dose responses of B. tectorum to sugar.
Book Synopsis Interaction Between Nitrogen and Carbon Availability on Microbial Activity and Biomass in Chaparral Soils of Southern California by : Kali C. Holt
Download or read book Interaction Between Nitrogen and Carbon Availability on Microbial Activity and Biomass in Chaparral Soils of Southern California written by Kali C. Holt and published by . This book was released on 2016 with total page 22 pages. Available in PDF, EPUB and Kindle. Book excerpt: A large portion of nitrogen deposition on southern California's chaparral and coastal sage scrub (CSS) is due to anthropogenic sources. The implications of increasing soil nitrogen, and the relationship between soil nitrogen and carbon on soil microorganism growth and activity, are not well understood. Possible interactions between N inputs and soil C availability on soil respiration and microbial biomass were assessed in chaparral and CSS plots that have been experimentally treated with N for about 12 years. Soil (microbial + autotrophic) respiration and microbial biomass were measured in four conditions: in plots exposed to added and ambient N, and within these plots, under shrubs and in open spaces, which represent microsites with differing N and C availability. We measured soil respiration and microbial biomass in these conditions every 3 months for a period of 1 year to test the hypothesis that respiration and microbial biomass would (1) increase in plots with higher C and N availability and (2) be higher during the winter and spring because of higher soil water availability. Our results indicate that soil respiration was significantly higher under shrubs but not in plots exposed to added N while microbial biomass was significantly higher in plots exposed to added N but not under shrubs. Soil respiration and microbial biomass were higher in the summer months than during the winter and spring months. These results were observed for both CSS and chaparral, indicating that the effects of long-term N exposure on soil microbial activity and biomass may be general for semiarid shrublands. While speculative, the N-induced increase in microbial biomass, without an increase in activity (respiration), suggests that N exposure has altered the soil microbial community. A change in the soil microbial community has important implications for soil N and C cycling and storage, especially in semi-arid chaparral ecosystems subject to large inputs of atmospheric N.
Book Synopsis Biogeochemical Effects of an Invasive Grass Across a Land-use Gradient: Linking Alterations of Nitrogen Cycling to Depleted Soil Carbon Pools by :
Download or read book Biogeochemical Effects of an Invasive Grass Across a Land-use Gradient: Linking Alterations of Nitrogen Cycling to Depleted Soil Carbon Pools written by and published by . This book was released on 2014 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Seasonal Priority Effects by : Claire Elizabeth Wainwright
Download or read book Seasonal Priority Effects written by Claire Elizabeth Wainwright and published by . This book was released on 2011 with total page 31 pages. Available in PDF, EPUB and Kindle. Book excerpt: Exotic annual grasses are invading native plant communities in many areas including the western United States, and pose a significant challenge to habitat restoration. Observations in California grasslands suggest that exotic species may become active earlier in the growing season than native species, and that this distinct phenology may contribute to invasion success. We hypothesized that flexible germination cues may allow exotic annual grasses to start annual growth early each growing season and preempt resources prior to native seedling establishment, a kind of seasonal priority effect. Flexible germination cues could incur a cost, however, if they cause seeds to germinate before the onset of favorable growing conditions. To evaluate these predictions, we compared native and exotic species performance in a coastal sage scrub community under both early (off-season) and ambient (natural) rainfall timings. Exotic annual grasses germinated substantially with off-season watering, but none of the early seedlings survived until the onset of the natural rains. Exotic annual grasses that experienced off-season watering had a depleted seedbank and lower germination following the natural rains. In contrast, native species did not germinate following the off-season watering pulse, and instead emerged with the beginning of the cold natural rains. Our results suggest that phenology is an important factor influencing invasion success and invader impact. Under some conditions, pre-growing season watering could be an important restoration strategy for native plant communities in early stages of invasion by depleting the exotic seedbank and allowing for native species to establish with reduced competition.
Book Synopsis Ecosystems of California by : Harold Mooney
Download or read book Ecosystems of California written by Harold Mooney and published by Univ of California Press. This book was released on 2016-01-19 with total page 1008 pages. Available in PDF, EPUB and Kindle. Book excerpt: This long-anticipated reference and sourcebook for CaliforniaÕs remarkable ecological abundance provides an integrated assessment of each major ecosystem typeÑits distribution, structure, function, and management. A comprehensive synthesis of our knowledge about this biologically diverse state, Ecosystems of California covers the state from oceans to mountaintops using multiple lenses: past and present, flora and fauna, aquatic and terrestrial, natural and managed. Each chapter evaluates natural processes for a specific ecosystem, describes drivers of change, and discusses how that ecosystem may be altered in the future. This book also explores the drivers of CaliforniaÕs ecological patterns and the history of the stateÕs various ecosystems, outlining how the challenges of climate change and invasive species and opportunities for regulation and stewardship could potentially affect the stateÕs ecosystems. The text explicitly incorporates both human impacts and conservation and restoration efforts and shows how ecosystems support human well-being. Edited by two esteemed ecosystem ecologists and with overviews by leading experts on each ecosystem, this definitive work will be indispensable for natural resource management and conservation professionals as well as for undergraduate or graduate students of CaliforniaÕs environment and curious naturalists.
Book Synopsis Effects of Invasive Grass and Fire on a Coastal Sage Scrub Food Web by : Mayda H. Nathan
Download or read book Effects of Invasive Grass and Fire on a Coastal Sage Scrub Food Web written by Mayda H. Nathan and published by . This book was released on 2008 with total page 54 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Seedling Establishment and Competition in Coastal Sage Scrub and Annual Grassland by : Gillian Polly Schultz
Download or read book Seedling Establishment and Competition in Coastal Sage Scrub and Annual Grassland written by Gillian Polly Schultz and published by . This book was released on 1996 with total page 128 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Diversity and Ecology of Invasive Plants by : Sudam Charan Sahu
Download or read book Diversity and Ecology of Invasive Plants written by Sudam Charan Sahu and published by BoD – Books on Demand. This book was released on 2019-12-18 with total page 114 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book, Diversity and Ecology of Invasive Plants, is a collection of reviewed and relevant research chapters, offering a comprehensive overview of recent developments in the field of invasive species biology. The book comprises chapters authored by various researchers and edited by experts active in the field of conservation of biodiversity. All chapters are complete in itself but united under a common topic. This publication aims at providing a thorough overview of the latest research efforts by international authors on diversity, distribution, and ecological consequences of invasive species and opens new possible research paths for further developments.
