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.

Download or read book Effects of Nitrogen Deposition on the Carbon Allocation and Nutrient Concentration of Southern California Vegetation written by Shelley Lawrence and published by . This book was released on 2015 with total page 32 pages. Available in PDF, EPUB and Kindle. Book excerpt: Coastal sage scrub and chaparral vegetation of Southern California have become fragmented due to a loss of habitat over the past several decades, which has been caused by several contributing factors such as agriculture, urbanization, increased fire frequency and intensity. Although nitrogen deposition has also been found to be a contributing factor to the loss of coastal sage scrub (CSS) and chaparral habitats in previous studies, the mechanism for these effects not been examined. Leaf tissue from existing field plots, fertilized with nitrogen since 2003, was analyzed for carbon allocation patterns and nutrient retention on a seasonal and annual basis from 2006, 2008 and 2010. Nitrogen fertilization did not have an effect on carbon allocation to cellulose, holocellulose or lignin fractions of leaf tissue in CSS California sagebrush (Artemisia californica) or chaparral chamise (Adenostoma fasciculatum) shrubs. However, it was found that seasonal and interannual variation in soluble carbon were highest in both species, but without any N treatment interaction. It was also found that year and season did have a significant effect on carbon allocation, and these temporal variations were correlated with precipitation rates and nutrient availability. The lack of nitrogen effect in the soluble carbon, holocellulose and lignin fractions suggests these avenues of carbon allocation are linked to life history traits that are specific to each species such as drought tolerance, woodiness, and maturation.

Download or read book Vegetation Responses to Anthropogenic Nitrogen Deposition and Nitrogen Fertilization in Chaparral and Coastal Sage Scrub of Southern California written by Sarah Cecilia Pasquini and published by . This book was released on 2008 with total page 140 pages. Available in PDF, EPUB and Kindle. Book excerpt: Mediterranean-type ecosystems of southern California are exposed to atmospheric nitrogen deposition with some areas receiving 20-45 kg N ha-1 annually. Although nitrogen is a limiting nutrient to plant growth, most nitrogen deposition in southern California occurs as dry deposition when plants are physiologically inactive due to seasonal drought. Due to this inactivity, it is unclear whether or not plants can utilize the additional nitrogen. The effects of nitrogen fertilization on aboveground plant production were tested in coastal sage scrub and chaparral ecosystems, and the effects of nitrogen deposition on post-fire recovery were observed in chaparral ecosystems. I found that experimentally added nitrogen did not result in increased production in either coastal sage scrub or chaparral sites. The vegetation did absorb added nitrogen but did not allocate aboveground production. Chaparral ecosystems did not respond to nitrogen deposition with increased rates of total or shrub biomass production post-fire but did show low density of large shrubs at high nitrogen deposition sites and high density of small shrubs at low nitrogen deposition sites. Since vegetation absorbs nitrogen but does not allocate it to increased production, it is important to discover the fate of the nitrogen because nitrogen deposition is projected to increase in southern California in future years. Key words: disturbance, Mediterranean-type ecosystems, semi-arid ecosystems, Adenostoma fasciculatum, Ceanothus, air pollution

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.

Download or read book Ecological Society of America Annual Meeting Abstracts written by Ecological Society of America. Meeting and published by . This book was released on 2005 with total page 788 pages. Available in PDF, EPUB and Kindle. Book excerpt:

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.

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.

Download or read book Carbon Gain Consequences of Leaf Aging in a California Shrub written by Christopher B. Field and published by . This book was released on 1981 with total page 292 pages. Available in PDF, EPUB and Kindle. Book excerpt:

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.

Download or read book Trace Gas Emissions by Plants written by and published by Academic Press. This book was released on 2012-12-02 with total page 381 pages. Available in PDF, EPUB and Kindle. Book excerpt: Many trace gases are exchanged between the atmosphere and the biosphere. Although much research has been published on the photosynthetic exchanges of carbon dioxide, oxygen, and water vapor, this book focuses on the importance of biogenic trace gases on atmosphere chemistry and ecosystem stability. Included are methane and its effect on the radiative properties of the atmosphere, hydrocarbons (isoprene and monoterpenes), and their role in the production of ozone and carbon monoxide. Also covered are sulfur and nitrogen gases, both of which can lead to ecosystem acidification. The biochemistry and physiology of production of these and other gases are investigated.Plant physiologists, ecologists, and atmospheric chemists and modelers will benefit from this book.

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.

Download or read book Effects of Mesophyll Surface Area on Gas Exchange and Leaf Resistances in a Desert Shrub Encelia Farinosa Gray written by Robin Lynn Kobaly and published by . This book was released on 1977 with total page 246 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Principles of Terrestrial Ecosystem Ecology written by F Stuart Chapin III and published by Springer Science & Business Media. This book was released on 2006-04-10 with total page 449 pages. Available in PDF, EPUB and Kindle. Book excerpt: Features review questions at the end of each chapter; Includes suggestions for recommended reading; Provides a glossary of ecological terms; Has a wide audience as a textbook for advanced undergraduate students, graduate students and as a reference for practicing scientists from a wide array of disciplines

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 Terrestrial Vegetation of California 3rd Edition written by Michael Barbour and published by Univ of California Press. This book was released on 2007-07-17 with total page 732 pages. Available in PDF, EPUB and Kindle. Book excerpt: "This completely new edition of Terrestrial Vegetation of California clearly documents the extraordinary complexity and richness of the plant communities and of the state and the forces that shape them. This volume is a storehouse of information of value to anyone concerned with meeting the challenge of understanding, managing or conserving these unique plant communities under the growing threats of climate change, biological invasions and development."—Harold Mooney, Professor of Environmental Biology, Stanford University "The plants of California are under threat like never before. Traditional pressures of development and invasive species have been joined by a newly-recognized threat: human-caused climate change. It is essential that we thoroughly understand current plant community dynamics in order to have a hope of conserving them. This book represents an important, well-timed advance in knowledge of the vegetation of this diverse state and is an essential resource for professionals, students, and the general public alike."—Brent Mishler, Director of the University & Jepson Herbaria and Professor of Integrative Biology, University of California, Berkeley

Download or read book Plant Response to Stress written by John D. Tenhunen and published by Springer Science & Business Media. This book was released on 2013-06-29 with total page 650 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book is dedicated to international cooperation, understanding and peace. It is the end result of several years of cooperative work between scientists of three countries: the United States, Germany, and Portugal. The work presented, however, draws from a much broader base, hopefully achieving the objective of NATO Advanced Research Workshops, which have been established to allow and stimulate the exchange of new ideas and the synthesis of information by scientists of NATO countries. The tasks of the workshop were several; to review established methodologies that have provided insight into ecosystem function and adaptations of plants in mediterranean climate zones; to examine new methodologies that have recently been applied in ecological studies and have provided new types of information; to summarize recent studies in mediterranean regions of plant water relations, photosynthesis and production, mineral nutrition, plant growth and development, and response to fire; to stimulate in particular an exchange of information among scientists of European Mediterranean countries; and to discuss means by which all of these objectives might be even more effectively achieved in the future through cooperative international research efforts. This variety of themes is clearly evident in the layout of the book. Held in Sesimbra, Portugal in October of 1985, the workshop took place in a ..

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.