Laura Gough, Ph.D. - US grants

Goldberg/Gough
DEB-9974296/DEB-9974284

This study will explore the influence of two important clonal attributes, clonal integration and ramet aggregation, on the outcome of interspecific interactions among clonal plants. It will develop a series of predictions about how these two characteristics influence both individual-level competitive ability and overall community structure. This will be done using a series of experiments using eight clonal species typical of calcareous peatland communities of southeastern Michigan. It is hoped that the work outlined in this proposal will integrate the currently disparate research areas of field studies of plant competition, clonal integration and foraging and theoretical studies of community-level consequences of spatial arrangement of individuals. This project will contribute to our knowledge of the ecology of clonal plants and to our understanding of how competition at the individual level is translated into species patterns at the community level.

This project will study factors controlling carbon flux from two tundra types that are largely differentiated on the basis of the underlying soil type: acidic vs. non-acidic. The factors leading to flux of carbon from each tundra type will be determined in order to examine the role of climate on landscape vegetation and subsequent carbon release or sequestration. A combination of field, laboratory, and modeling studies will be preformed to examine the factors controlling carbon flux in each tundra soil type. A model will be developed to look at possible future scenarios for warmer climates so that the role global warming in the Arctic may be assessed. The study is critical for understanding climate impacts on tundra composition and concomitant carbon flux on a regional scale. Current understanding of tundra soil effects on carbon flux are limited to only one soil type in spite of the prevalence of the other type as well.

0083752
Ward

Faculty from the University of Alabama and the University of
New Mexico will coordinate development of a Biocomplexity
research proposal that (1) advances our current, limited
understanding of how droughts are initiated and maintained; and
(2) provides assessments of impacts of drought in river basins in
the contrasting mesic and semi-arid climates of Alabama and
New Mexico. We will develop a new, quantitative understanding
of biological, hydrological and atmospheric interactions that control
initiation, duration, and consequences of drought. Our ultimate
goal is to understand biotic response to drought well enough to
make estimates of climate feedback and contribute to better
predictive climate models. The planning proposal will fund
analyses and integration of relevant data sets from both regions,
travel for faculty exchanges, and full-group workshops to facilitate
preparation of a biocomplexity and other interdisciplinary research
proposals appropriate for this theme.

0137832
Gough

Terrestrial arctic research has tended to focus on plant populations or the entire ecosystem, with community patterns and processes less well studied, generating a lack of predictive ability of effects of climate change on different arctic plant communities and potential biotic feedbacks to an altered environment. This proposal seeks better understanding of vegetation patterns at the community level as well as of how processes at the ecosystem level are influenced by plant community composition. The PI currently has two NSF-funded research grants. One project is examining two common arctic plant communities in northern Alaska, moist acidic and moist non-acidic tundra. By monitoring plant responses to nutrient and temperature manipulations in both communities, and conducting experiments to examine germination and survival of important species, the PI is determining how the communities are maintained and how they respond differently to manipulations. The differences are being linked to ecosystem function through collaboration with an ecosystem ecologist. The second NSF grant is examining competition among seven clonal sedge species in southeastern Michigan calcareous wetlands. Although clonal growth is the dominant method of production of new individuals by plants in many ecosystems, including tundra, its effects on plant community structure remain unclear. Using community and individual-level experiments, the PI is examining both short- and long-term effects of competition among species that differ in clonal growth form; the results of this project are being used to generate new hypotheses to be tested in arctic plant communities. From this work, the population-level processes that have been well documented for some arctic plant species can be explicitly linked to the community and the ecosystem, thus providing better understanding of patterns and processes at all levels of organization, as well as predictions for biotic feedbacks to the changing arctic environment.

This award is supported through the NSF ADVANCE Program. The overall mission of the ADVANCE Program is to increase the participation of women in the scientific and engineering workforce through the increased representation and advancement of women in academic science and engineering careers.

While existing observations suggest that arctic plant communities undergo dramatic changes in species composition, net primary productivity (NPP), and biomass in response to climate warming and subsequent increased soil nutrient mineralization, current models used to predict carbon (C) and nitrogen (N) cycling in arctic tundra are lacking inclusion of higher trophic levels and, thus, are missing mechanisms that may be having considerable effects. Funds are proided to concurrently measure plants, soil invertebrates and microbes (biomass and diversity) as they respond to increased soil nutrients to test ecological theory regarding such changes and understand feedbacks among trophic levels. The proposed work addresses whether we are witnessing simple
increases and subtle shifts in the ecosystem components or fundamental changes in the ecosystem that have the potential to alter the current balance of biota, carbon and nitrogen.

Theory suggests that when NPP increases, additional trophic levels should enter the system because there is now enough energy to sustain them. These changes will be more dramatic in lower NPP systems, such as arctic tundra, because the dynamics are not linear. The study will examine how soil communities and nutrient cycling respond to changes in plant growth and how these responses compare between two common arctic ecosystems that differ in NPP, dry heath and moist acidic tussock tundra. It will use existing experimental plots of the Arctic LTER at Toolik Lake, Alaska to test these hypotheses at the plot scale under long-term nutrient enrichment and will establish new smaller-scale nutrient amendment experiments on which more localized and frequent plant and soil sampling will occur to capture a temporal and spatial scale more appropriate for soil organisms. Theoretical and empirically-based models will be used to aid in the analysis and interpretation.

The Undergraduate Training in Theoretical Ecology Research (UTTER) program at the University of Texas at Arlington provides an integrated research and education experience for cohorts of undergraduates in biology and mathematics. Five cohorts of eight students each pursue a two-year program of mentoring, seminars, interdisciplinary research, and specially designed coursework in mathematical biology, with each component and new course being jointly developed and coordinated by six faculty members from biology and mathematics with experience in interdisciplinary research and education. UTTER's four primary goals are: (1) to recruit talented students from historically underrepresented groups to complete interdisciplinary training in mathematical biology; (2) to develop curriculum and infrastructure for this training through new courses and formalized interactions between faculty and students from the two departments; (3) to involve participating students in interdisciplinary research through structured and mentored long-term experiences within and across cohorts; and (4) to facilitate participant transitions into graduate studies and other interdisciplinary careers following program completion and graduation.

The intellectual merit of the project lies in: (1) the integration of mathematics and biology into each of the research projects, and how each of the projects helps students develop specific skills; (2) the continued development of an interdisciplinary curricular framework to support students as they pursue their research and to encourage the development of an on-going community of students interested in theoretical ecology; and (3) the strength of the research projects which are all significant, conceptually interesting and timely, and which all fit well under the general theme of theoretical ecology.

The project's broader impacts include: (1) its focus on the recruitment and support of students from underrepresented groups, particularly through a recruitment plan targeting local community colleges; (2) the development of three new interdisciplinary courses that involve many students other than those directly participating in the project and foster a culture of interdisciplinary cooperation among faculty; and (3) the development of new models of effective interdisciplinary undergraduate training in mathematical biology as well other academic areas.

This award is funded under the American Recovery and Reinvestment Act of 2009 (Public Law 111-5).

The goal of this project is to determine how plants, microbes and soil invertebrates interact to drive changes in soil organic matter and carbon sequestration with ambient and increased soil nutrient availability in the dominant upland arctic tundra ecosystem in northern Alaska. The proponents will use a combination of field observation, experimental, laboratory, and modeling approaches to address four research objectives that include:
1. Understanding how well-documented changes in the plant community alter plant inputs to soils (roots and litter)
2. Determining how soil microbial and invertebrate communities respond to these inputs
3. Investigating if the loss of SOM occurs in response to an increase in soil activities and/or a change in community structure, and
4. Developing a model of soil pedogenesis based on the DAYCENT model (Parton et al. 2001) that incorporates the roles of plants, microbes, and invertebrates.
This work will be conducted at the Toolik Lake Long-Term Ecological Research site and will utilize a suite of long-term nutrient-addition plots (some extending back over 30 years) as well as more recently manipulated sites. A postdoctoral researcher, at least two graduate students, and several undergraduates will be trained as part of this project. The PIs will also conduct teacher development workshops and other K-12 outreach programs.

As a consequence of global warming, arctic North America has been ?greening? over the past several decades, with increases in relative abundance and size of shrubs documented in numerous locations. Much of the research on this topic examines how this shift toward more woody species affects element cycling, particularly carbon, with potential feedbacks to the atmosphere regionally and globally. To date, the response of higher trophic levels to such shifts in vegetation in the Arctic has not been well studied. One group that has been almost completely ignored is migratory songbirds; they have a complex relationship with shrubs that provide both shelter and food, both of which are directly affected by weather patterns. This research will characterize the interactions between tundra vegetation and migratory songbirds in habitats that differ in shrub dominance for five consecutive growing seasons that will differ in timing and severity of weather events. The team will 1) identify and characterize interactions between shrub dominance and weather to determine how these affect food and shelter availability for migratory songbirds; 2) examine how reproductive success of populations of two songbird species responds to variation in both shrub dominance and timing of spring snowmelt, and; 3) measure how both variation in shrub dominance and timing of spring snowmelt affect composition and size of the entire songbird community. The multi-year approach will allow for examination of how interannual variability in arctic seasonality, particularly the timing of snowmelt, impacts songbird communities. Because the increasing shrub dominance is occurring too slowly for organisms to respond to during the time period of a grant, the researchers will examine habitat usage in open tundra plots, moderate shrub dominance plots, and high shrub dominance plots, at each of four study sites on the North Slope of Alaska. These include Atigun Valley, one of the first tundra stops made by migratory songbirds as they travel north, and at Toolik Lake, farther north, including two additional sites farther north to increase the spatial scale of sampling. In five project years, they will sample intensively at all four field sites to investigate spatial and temporal variation in plant resources, arthropod abundance, songbird community composition, and the arrival, settlement and reproductive success of two songbird species. During five years they hope to capture a range of interannual variability in weather, onset of spring snowmelt, and biotic responses to provide and understanding of current relationships and to predict how future changes in climate and vegetation may affect these organisms. They also intend to verify the use of remote techniques for monitoring bird community attributes via bioacoustic recordings for conducting automated bird community censuses.

Small mammals graze on the vegetation of the Arctic tundra. Although this grazing may influence many aspects of tundra ecosystems, current models do not include grazing by small mammals. In this project, the abundance of voles and lemmings will be varied experimentally using fenced plots. The investigators will observe the responses in the plots, especially focusing on changes in the cycling of carbon and nitrogen. To understand how the current climate controls the importance of grazing by small mammals, the investigators will conduct their studies at three sites in Alaska located in the Seward Peninsula, the foothills of the Brooks Range, and on the Arctic coastal plain. The natural abundance of voles and lemmings will be studied at these sites to provide background for applying the experimental results throughout the Arctic. The results will be used to expand a mathematical model of tundra ecosystems to include grazing by small mammals, which will improve the predictions that can be made about how the Arctic may change in the future. The research will involve a number of undergraduate students and investigators will integrate their research into classes and other educational programs. In addition, they will present a radio program in Barrow, AK.

The investigators will investigate the importance of herbivory by small mammals in controlling the cycling of carbon and nutrients in the rapidly changing Arctic tundra. Through studies at three sites along a latitudinal gradient, the investigators will employ both observations and experiments to quantify the role of grazing by rodents (voles and lemmings) in the functioning of tundra ecosystems. The observations of rodent population dynamics along with ecosystem function will provide key new information relevant to understanding the feedbacks of the Arctic tundra to the global climate. The manipulation of rodent density through exclosures and enclosures will show how potential changes in rodent populations may influence the tundra ecosystem response. In corporation of the observational and experimental results into a quantitative ecosystem model will enhance predictions of future changes and feedbacks with climate.