1995 CROSS-SITE COMPARISONS & INTERNATIONAL AWARDS - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - Mycorrhhizal Responses to Nitrogen Eutrophication at Five Mesic to Semiarid Sites PI Names: Edith Allen and Nancy Johnson Duration/Amount: 36 months, $200,000 Award #: 9526564 (Allen) & 9527317 (Johnson) Although nitrogen is frequently the most limiting nutrient in ecosystems, continuous, elevated inputs of nitrogen may cause significant ecosystem stress. Deposition of anthropogenic nitrogen has been associated with recent losses of plant as well as fungal diversity throughout Europe. Little is known about the effects of atmospheric nitrogen deposition on the structure and function of North American grasslands and shrublands, although as much as 30 kg nitrogen per hectare per year is deposited in southern California, with lesser amounts elsewhere in the United States. The three principal objectives of this research will be to (1) assess species composition changes of fungi during nitrogen eutrophication in mesic to semiarid grasslands using microscopy and immunoflourescence, (2) assess the kinds of mycorrhizal fungi under nitrogen eutrophication to indicate the mutualistic or parasitic effects of fungi, and (3) conduct bioassays to determine whether inferior mutualists predominate after nitrogen eutrophication. This study will examine the effects of nitrogen eutrophication on mycorrhizae at four experimental grasslands within the Long-Term Ecological Research Network and at a shrub-grasslands in southern California. These grasslands in Michigan, Minnesota, Kansas, New Mexico, and California form a precipitation and fertility gradient. The effects of nitrogen eutrophication will be studied on plants, mycorrhizal fungi and soils in experiments that have previously been established in new plots at these sites. This research is designed to assess the ranges and variances of mycorrhizal responses to nitrogen at three scales: at individual plant-root interfaces, within grasslands communities, and across a climatic and soil gradient. This is a first step toward assessing the potential effects of nitrogen eutrophication on the structure and functioning of mycorrhizae-plant interactions in grasslands in the United States. This research is important because grasslands are the basis for range resources and beef production in North America. - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - Earthworms and Soil Processes in North American Ecosystems PI Name: Paul Hendrix Duration/Amount: 36 months/$200,000 Award #: 9527365 Influences of earthworms on soil processes in agricultural and pastoral systems are well recognized but there is considerably less information about their importance in wildland ecosystems such as forests, grasslands and savannas. Furthermore, very little is known about the ecology of native earthworm species in North America, even though they are prevalent in a number of areas unaffected by Pleistocene glaciations. The few existing studies indicate that where they are abundant, these organisms can have significant effects on soil structural properties and on nutrient transformations. However, the relative importance of native versus invasive exotic earthworm species remain virtually unknown. This proposal requests funding for a cross-site investigation of native and exotic earthworms, to determine if native species are more efficient than exotic species in nutrient processing in undisturbed ecosystems. They also will determine if disturbance sets the stage for invasion by exotic earthworms, which may be more competitive than natives but less effective in nutrient cycling. These ideas will be tested in two phases over a three- year period at three LTER sites (Coweeta Hydrologic Laboratory, Konza Prairie Research Natural Area and Luquillo Experimental Forest) and one non-LTER site (Apalachicola National Forest). They will undertake field surveys and collections in a variety of habitats, and will initiate field enclosure experiments using 13C- and 14N-enriched substrates. Together, these two phases of work optimize the use of stable isotopes in field studies--resource utilization across sites; and then as biogeochemical tracers to elaborate earthworm-microbial interactions and to quantify influences of various earthworm species on C and N dynamics. Results from this study will greatly expand their understanding of earthworm ecology, interactions between native and exotic species, and influences of both groups on soil nutrient processes across a broad range of ecosystems. - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - Stream Flow Hydrology Comparisons and Synthesis at LTER Site--Links with Climate Terrestrial Ecosystems and Stream Ecology PI Name: Julia Jones Duration/Amount: 24 months/$200,000 Award #: 9526987 This project is designed to further understanding of relations among climate, vegetation, and streamflow across a range of ecosystem conditions and to advance intersite activities among LTER and non-LTER sites. The overall objective of this proposal is to describe streamflow hydrology in a wide range of sites by elucidating streamflow response to a range of climate, vegetation, and disturbance factors operating at time scales ranging from decadal to diel. We expect to demonstrate how streamflow responds to vegetation and climate at each of these scales, and how this inherent coupling of climate, vegetation and streamflow controls streamflow response to disturbance and hence aspects of stream ecology. The initial research phase of the project involves comparative rative analysis of long-term steamflow records from Andrews, Coweeta, and Hubbard Brook LTER sites and the Caspar Creek Experimental Watersheds site (USDA Forest Service/State of California). These forest sites encompass a broad range of climatic (e.g., precipitation amount and seasonality, degree of snow influence) and vegetation (e.g., deciduous vs. conifer, leaf area index) conditions. Subsequently, they will involve a much larger group of LTER and other sites in a workshop and associated activities designed signed to develop site characterization and cross-site analysis for broader range of site conditions. This work will include use of hydrologic models to examine hypotheses concerning controls on water balances at the time scales of interest. Representatives of the Climate and Stream Ecology Committees of LTER will take part in workshop planning and conduct. Products of the overall effort will include: (1) on-line data bases with common variables/time resolution between sites, (2) an LTER publication similar ar to LTER Publication No. 15, *Stream Research in the LTER Network*, and (3) journal articles from the comparative analyses conducted for the small set of sites and for the larger set of sites. - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - Groundwater Influences on the Littoral Communities of Lakes: Recent and Long-Term Impacts PI Name: Wilson Kerfoot Duration/Amount: 36 months/$200,000 Award #: 9527358 The emerging new field of groundwater ecology asserts that certain biota are characteristic residents of groundwater and that there are important couplings between groundwater and surface-water biota. One hypothesis is that groundwater flow influenced benthic algal species composition in lakes. Here we propose to critically address important short-and long-term groundwater/biotic diversity interaction by Sparkling Lake Nevins Lake, MI and Williams Lake, MN. The research will assess how nutrients delivered by groundwater influence the species composition benthic diatoms at discharge and recharge sites, how dispersal of characteristic diatoms from that discharge contributes to within-lake diatom diversity, and how the long-term consequences of groundwater coupling can be followed in sediment cores. The proposed investigations would expand and complement long-term studies at the three sites and surrounding regional studies. - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - Spatio-Temporal Dynamics of Canopy and Soil Moisture: Linking Synthetic Aperture Radar Image Phenomenology with Ecosystem Processes PI Name: Alan Knapp Duration/Amount: 36 months/$150,000 Award #: 9527108 Soil moisture is a key controlling factor for numerous ecological and biophysical processes. While diverse techniques are available to make point estimates of soil moisture, spatially extensive surveys can be logistically difficult and fraught with problems ms of interpolation. Remote sensing of soil moisture offers the possibility of exhaustive spatial sampling. The efficacy of microwave sensors (both active and passive) in measuring soil moisture is well-studied. However, little research has focused on patterns of radar imagery of natural landscapes. Yet, there is a distinct need to assess the potential of Synthetic Aperture Radar (SAR) for routine environmental monitoring of land surface processes. Environmental monitoring of vegetated landscapes will increase during the next decade as data from spaceborne SAR platforms become more readily available. The project involves the use of SAR data from the European, Canadian, and Japanese orbital platforms to address the variation in canopy and soil moisture and its ecological consequences. These data augment current investigations at two NSF Long-Term Ecological Research (LTER) sites, Konza Prairie Research Natural Area in the northeast Kansas and Sevilleta National Wildlife Refuge in central New Mexico. Both LTER sites are located within ecological transitional zones (ecotones) in which soil moisture is a major determinant of plant productivity and species composition. The primary products are site-specific time series of soil moisture and canopy change maps. These data will then be used to link remote sensing and groundtruth data with ecological processes. - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - Microbial Loop Dynamics and Regulation of Bacterial Physiology in Subtropical and Polar Marine Habitats PI Name: David Karl Duration/Amount: 24 months/$200,000 Award #: 9526986 The microbial loop has been shown to play an important role in marine and freshwater plankton ecosystems in all climatic zones. Earlier research in two contrasting habitats: an Antarctic coastal/shelf/oceanic ecosystem and a subtropical oceanic ecosystem, have shown significant differences in the ecological role of the microbial loop and the physiology of bacterioplankton. These two habitats are isolated from input of terrestrially derived organic matter and so provide excellent opportunities to study bacterial metabolism of autochthonous organic matter of phytoplankton origin. Strong contrasts in plankton community parameters make these two sites ideal for this comparison. This study will be embedded within on-going programs at each of these two sites (U.S.-JGOFS Hawaii Ocean Time-series in the North Pacific and Palmer LTER in Antarctica) that provide both logistical support and supporting data on a wide range of hydrographic, chemical and biological parameters, with extensive documentation of spatial and temporal variation. Preliminary field results show that bacterial communities in these two areas are physiologically distinct, that bacterial physiology is regulated by the structure of the microbial community and particularly by grazer recycling of nitrogen, that organic compounds rare in seawater, especially histidine, play a large role in regulation of bacterial ectoenzyme expression, and that photolysis of dissolved organic matter by solar ultraviolet radiation also plays a role in regulation of bacterial ectoenzymes. More thorough investigation of these phenomena in ecologically distinct microbial communities will facilitate understanding of the complex interactions between bacterioplankton and the rest of the microbial community. - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - The Effects of Indigenous Small Mammals on the Species Composition and Structure of Chihuahuan Desert Communities: A LTER Cross-Site Research Project PI Name: David Lightfoot Duration/Amount: 36 months/$200,000 Award #: 9527083 They propose to expand an existing LTER research project to a site in Mexico. They will examine the roles of indigenous small mammals as keystone species determining plant species diversity and vegetation structure across the Chihuahuan Desert grassland and shrubland ecosystem. The Sevilleta LTER site is located at the northern biome transition of the Chihuahuan Desert/Great Plains grasslands, while the Jornada LTER site is in the north-central Chihuahuan Desert. They propose to add a new research site, the Mapimi Biosphere Reserve (United Nations Man and Biosphere Program), located in the south-central Chihuahuan Desert. This cross-site research project will involve university scientists with scientists from the U.S. Department of Interior, Fish and Wild life Service (Sevilleta National Wildlife Refuge), the U.S. Department of Agriculture, Agricultural Research Service (Jornada Experimental Range), and Mexican scientists (Institute of Ecology, Mapimi Biosphere Reserve). Previous research demonstrates that indigenous small mammals are keystone species in Chihuahuan Desert ecosystems. Other research demonstrates that many Chihuahuan Desert ecosystems have become desertified as a result of human disturbance, and the persistence of desertified landscapes may result from plant resource use and physical soil processes alone. They will experimentally determine how small mammals affect Chihuahuan Desert ecosystems, and how small mammal influences are affected by short-term and long-term climate change both local locally, and regionally across the Chihuahuan Desert. They will also integrate a cross-site data management network to centralize and coordinate data management activities for the proposed research project. This data management network will include the addition of a real-time satellite communications link at the remote Mapimi research site in Mexico, to link that site to the existing LTER Network. The respective U.S. LTER sites, and the Institute of Ecology in Mexico will continue the long-term operation of this study beyond the three years of this requested award. - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - Collaborative Research: Effects of Different-sized Herbivores on Grassland Plant Diversity PI Name: Daniel Milchunas Duration/Amount: 36 months/$200,000 Award #: 9527585 This study addresses the effects of different-sized mammalian herbivores on plant diversity at six different North American grassland sites. These sites represent two sets of sites that differ in their inherent site productivity. One hypothesis is that differences in productivity will lead to very different effects of herbivores on plant diversity. At low productivity sites, most plant species are of sufficiently high quality to be consumed by all herbivores, but are defended such that larger herbivores e at inferior plants, while smaller herbivores feed on seeds of dominant plants. At high productivity sites, competitively dominant species may be consumed only by larger herbivores that can accommodate their low N content. These trade-offs suggest that larger larger herbivores will have greater effects on plant biomass at high productivity sites, while smaller herbivores will have greater effects on biomass at low productivity sites. In addition, larger herbivores may increase diversity at high productivity sites and reduce it at low productivity sites, while smaller, more selectively foraging herbivores may have the opposite effects. The goal for this proposal is to begin monitoring for the first three years of a long-term (next 10 to 20 years) program as it is likely that changes in plant species composition and diversity will require that long to respond fully to treatments. The collaborative network of LTER and other sites committed to support this project should greatly facilitate such monitoring. The result s should provide a general understanding of the role of herbivores in controlling grassland plant diversity, and should aid efforts to restore, preserve, and manage grassland ecosystems. - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - Collaborative Research with Daniel Milchunas (see #9527535) PI Name: Richard Inouye Duration/Amount: 36 months/$200,000 Award #: 9527584 - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - Collaborative Research with Daniel Milchunas (see #9527585) PI Name: Mark Ritchie Duration/Amount: 36 months/$200,000 Award #: 9527250 - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - Saurian Malasia: A Long-Term Study PI Name: Joseph Schall Duration/Amount: 36 months/$200,000 Award #: 9527115 This project will continue long-term ecological studies on the malarial parasites of lizards. Three sites will be used: (1) the Hopland Field Station in northern California where field and laboratory studies on lizard malaria have been underway for 17 years, (2) the Luquillo LTER site in Puerto Rico where preliminary data were gathered, and (3) the eastern Caribbean island of Saba where other recent surveys have been conducted. The broad goal of this project is to continue studies at all three sites for at least the next decade. The research will examine the distribution, abundance, sex ratio, and interspecific interactions in three species of malarial parasites in lizard hosts. One species of malaria infects the western fence lizard in California. The ecology of this species is perhaps the best known of any non-human malaria. Two other malaria species coexist in the Caribbean. Parasite abundance, sex ratio, and interspecific associations all interact over ecological and evolutionary time. These long-term studies will provide the necessary base-line data for understanding this host-parasite system. Three issues will be addressed. First, the distribution and abundance of the parasites will be followed over time and compared among sites. Classical and recent models of parasite prevalence will be explored with these data. Second, recent theory on sex ratios of malarial gametocytes will be tested by taking advantage of the different levels of prevalence at the tropical and temperate sites and as parasite prevalence alence changes over time. Third, interspecific interaction, especially facilitation, will be explored for the two coexisting species of malarial parasites at the two tropical sites. The relative and absolute abundances of the two parasites could effect in interactions between the lizards. Malarial parasites are a diverse, geographically widespread group. Their importance to the biology, including population biology, of humans is well documented. Studies on lizard malaria now suggest that Plasmodium can be of central importance to non-human hosts as well, including population and even community-level effects. The Anolis lizards of Caribbean islands are extremely abundant and influence the entire biotic environment because of their diet of insects. Thus, lizard d malaria can stand as a model system to study host-parasite ecology and its impacts on other aspects of the biota. - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - Analysis of Past and Current Changes in Grass-land Ecosystem Dynamics in Asia and North America PI Name: Larry Tieszen Duration/Amount: 36 months/$200,000 Award #: 9527303 We propose a three year project to investigate the role and consequences of changes in climate, land use, vegetation, and soils of the temperate grassland ecosystems of Asia and North America. The objective of this study is to characterize the factors con trolling ecosystem integrity relative to changes in climate and land use of North American and Asian grasslands, and to understand these changes relative to the presence and distribution of C3 and C4 species in these two regions. Although plant productivity tends to be greater for the same amount of rainfall in the Asian continent, the occurrence of C4 species in the Asian grasslands is greatly reduced compared to the North American grasslands. They will incorporate isotopic analysis of soils and vegetation on across a gradient of rainfall and temperature in Asia and compare these to similar analyses collected in North America. This information will be integrated using the CENTURY ecosystem model to investigate climate-soil-land use interactions on soil and vegetation dynamics. Isotopic signature 813C will be compared across similar topo-edaphic positions of plant communities in different regions of the two continents. Remote sensing will provide the land cover template to evaluate the degree of changes from natural vegetation. These differences will be used in conjunction with the CENTURY model to evaluate net changes in ecosystem properties at the regional scale and the susceptibility of these grasslands to climate change and human activities. - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - Within- and Across-Site Variation in Ant Community Structure and Ecosystem Functions at Three Semiarid LTER Sites PI Name: John Wiens Duration/Amount: 36 months/$200,000 Award #: 9527111 This research will employ cross-site and within-site comparisons using three LTER sites to extend and enrich our knowledge of biodiversity and its dynamics at these sites and establish a baseline for understanding the long-term dynamics of a critical and sensitive component of these ecosystems. To answer this question they will document how species and communities of ground-dwelling ants respond to local and regional gradients in vegetation and land-use between the Central Plains site (Colorado shortgrass steppe), the Sevilleta site (transition between grassland and Chihuahuan Desert), and the Jornada site (Chihuahuan Desert). The work focuses on ground-dwelling ants because they are easily sampled and observed, are abundant and diverse, are characterized by strong behavioral and competitive interactions, are sensitive to both small-scale and large-scale environmental variations, and may play a major role in the movement of materials in arid and semiarid ecosystems. The sites represent a gradient in temperature, precipitation, vegetation, and biogeography. Within each site, ant communities and functional roles will be compared in grass-dominated and shrub-dominated vegetation and in locations differing in grazing intensity. Observations at nest sites of foraging individuals and of removal of seeds and mealworms from food stations will be used to document how the relative magnitude of material flow generated by ants of different functional groups differs among habitats within a site and how these differences are affected by factors operating at the regional scale. - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -