Stuart G. Fisher - US grants

The investigators will study the extent to which a stream ecosystem is a source or sink for energy and nitrogen in the larger desert landscape. Energy flow will be summarized as the ratio of primary production to respiration (P/R) and nitrogen cycling as the ratio of dinitrogen fixation to denitrification (F/D). Judgments of whether a system is a source or sink will be generated for nested hierarchys, ranging from the algal assemblage to the entire drainage. Results will test in part the utility of hierarchical approaches to steam ecology. Disturbance effects generated by flash flooding and drying, each characteristic of a different hydrologic extreme, will be studied in the context of the hierarchy. Stability of subsystems will be evaluated in the face of each disturbance and combinations of the two. Detailed study of interactions between surface and hyporheic zones involving organic carbon and inorganic nitrogen will be used to explore how subsystem interaction influences the stability of each. The hypothesis is that vertical exchange enhances resilience of both subsystems. Finally, a simulation model will be used To simulate the effect of disturbance regimes on the whole drainage system. Results will show how disturbance regimes of several years length influence the linkage of streams with adjacent ecosystems: downstream reservoirs, groundwater aquifers, or parallel riparian communities. The investigators are well qualified to run the proposal research program, have adequate facilities and have an excellent publication record.

This project will describe the spatial and temporal patterns of trophic structure and the proportion of total biomass in primary producer, primary consumer, and secondary consumer trophic levels in a desert stream ecosystem. The spatial context for this description will be a hierarchical arrangement of patches from the relatively small scale of algal or macrophyte assemblages to large scale run-riffle-pool habitats. Temporal change will be assessed along successional trajectories associated with flooding and drying. Losses and gains of biomass at each trophic level will be evaluated both within and between patches to determine how patches are linked. Experiments will identify mechanisms shaping trophic structure and causing observed temporal changes in trophic structure. Mesocosm experiments will manipulate resources and consumers in 3-level systems, and a natural stream experiment will manipulate nutrients and top predators. Descriptive and experimental results will be used to evaluate ecosystem-level consequences of specific trophic configurations; this evaluation will indicate whether change in community-level properties drives change in ecosystem structure and function. This research explores questions concerned with the relative influence of top-down (propagated from the top to the bottom of the food chain) and bottom-up (propagated from the base) processes in determining patterns observed in nature. These are important issues concerned with the responses of ecological systems to disturbance. The facilities for this research are excellent; the investigators are productive and innovative experts in the area of stream ecology.

9306909 Fisher This research will determine the effect of spatial configuration on nutrient retention in stream-riparian ecosystems. Streams are complex, heterogeneous systems consisting of a wetted channel, saturated sediments below and adjacent to the wetted channel, and a strip of terrestrial vegetation (the riparian zone) at each lateral edge. The extent and shape of each of these varies greatly in space and time. As water flows downstream, it moves to varying degrees among these components. Because of several favorable properties, streams of arid lands will be used as model systems for this study. The overall goal of this project is to determine how configuration affects the extent to which materials transported in this water are retained and recycled within a given reach. This goal will be met by addressing four questions around which the research is organized. First, how does spatial pattern influence nutrient retention? Spatial configuration and its effects will initially be considered for a single point in time. This will be accomplished by mapping the stream ecosystem a two scales to determine its physical configuration, describing hydrologic connections among these elements, and the consequences of flow path for retention of nutrients. Configuration will be manipulated experimentally to determine the effect of different patterns on the retention process. Second, how does disturbance affect this relationship? Several individual flash flood and drought events will be studied in terms of their effect on configuration and recovery of system function between events. Third, how do configuration and function interact over large spatial and temporal scales? This analysis will involve scaling up reach-scale processes to include geomorphic variation generated by valley floor width. Temporal scaling will be accomplished by considering the effect of variable flood and drought regimes; their frequency , intensity, and distribution in time. Fourth, how general are results derived from North American desert streams for this ecosystem type worldwide? This question will be answered with a comparative study of the pattern-process relationship among streams of similar deserts in Australia and Spain. %%% This research is significant in that it will contribute to basic scientific understanding of how pattern and process interact in complex ecosystems. It is an advance over black box, well-mixed reactor models that have been commonly used in ecosystem ecology. Research results will be useful to applied ecology as well. Streams are open systems which link terrestrial uplands with downstream reservoirs, groundwater supplies, or estuaries. Retention and transformation of stream load in transit affects the quality of water delivered to recipient systems. Riparian and other wetland ecosystems are increasingly used for this "nutrient filtration" capacity. Results of this research will aid in understanding this process in natural streams and optimizing it in managed and human-designed systems. ***

9317340 Grimm

This proposal is submitted under a special pilot program, Undergraduate Mentorships in Environmental Biology. The four year program will offer undergraduate students first hand experience in carrying out ecological research under the mentorships of six active research ecologists. We will aggressively seek to involve groups traditionally under represented in environmental biology, includi ng trainees of Latino, American Indian, and African American backgrounds as well as a number of non minority students. This effort will be aided considerably by close coordination with existing programs that target these minority groups at ASU. The program is a specialized educational track consisting of an integrative first year seminar, early exposure to advanced courses, research involvement at the outset of students' college careers, and continued follow up and support of individual students as they make plans for graduate school and future careers. Careful documentation of the program's successes and failures, support from other research experience programs targeting more advanced undergraduate students, and placement of students in individual laboratories will facilitate the entry of alumni and alumnae of this program into research careers in environmental biology.

Grimm 9714833 This project is a long-term study of the Phoenix metropolitan area and fringing regions of central Arizona into which Phoenix is rapidly expanding. Objectives of this LTER program are to: 1) generate and test general ecological theory in an urban environment, 2) enhance understanding of the ecology of cities, 3) identify feedbacks between ecological and socio-economic factors, and 4) involve K-12 students in the enterprise of scientific discovery. Phoenix is one of the largest and most rapidly growing cities of the arid and semi-arid American west. Because Phoenix is young, urban redevelopment is minor compared to expansive growth of the city's edges, where agricultural lands and natural desert habitats are being rapidly converted to suburbia. Historic patterns of growth will be reconstructed using maps, planning documents, aerial photographs and satellite imagery to generate a GIS-based record of urban change. Modeling will be centered on a hierarchical, spatially-explicit, patch-dynamic approach, based on land-use patch types. At intermediate scales, landscape models will be developed to determine configuration effects of multiple patches. A regional simulation model of the entire area will be developed to predict and test ecological consequences of alternative patterns of future development. Patch-specific ecological characteristics will be monitored in five core areas: primary production, natural population and community characteristics, storage and dynamics of organic matter, movement of materials (including water), and patterns of disturbances by redevelopment, fire and flood. A successional model will guide this work; both short-term ecological trends associated with land-use change at the patch scale, and long-term changes as patches mature will be followed. Of special interest is ecological change within a given patch type on the city-center to suburban-edge gradient. Socioeconomic factors are included in this study as feedbacks between land-use decisions and ecol ogical characteristics. That is, how do ecological features shape land-use decisions and how, in return, do ecological consequences modify future land use policy? Research will determine the importance of ecological factors to individual perceptions of quality of life. In addition, objective analyses of change in property values and shifting demographic patterns within the urban landscape will be assessed as an indicator of ecological and other values. These efforts will be enriched by multiple partnerships with agencies and municipalities. This research effort includes a substantial commitment to K-12 education by involving teachers and students as hands-on research partners, through interaction with developing urban science curricula, and by providing a real time electronic interface with research discoveries via the Internet. This component of the project is enhanced by a strong interface with numerous educational partners in the greater Phoenix area.

Abstract 97-27311 Fisher Integrating linkages among aquatic and terrestrial components of arid landscapes This research will address the following puzzle: In the arid Southwest, atmospheric deposition of nitrogen (N) exceeds export by streams and rivers. While measurements suggest a huge (>10-fold) annual storage increment in the catchment and widespread N enrichment of the landscape, the opposite is true - usable N is rare. Both terrestrial and aquatic primary production are N-limited, and N2 fixing organisms abound in both environments. The objective of this project is to identify the hot spots (in space and time) for N transformation and retention and thereby account for the catchment-level N discrepancy. The investigators will focus on methods development for the flowpath approach; experiments in the uplands, tributary system and stream-riparian corridor; and developing an understanding of variance in these systems. The work will concentrate on processes rather than patterns, and is expected to lay the underpinnings for linkages between the empirical work and conceptual and mathematical models now under development.

9987612
Stuart Fisher - Arizona State University
IGERT: Integrative Graduate Education and Research Training in Urban Ecology

This Integrative Graduate Education and Research Training (IGERT) award supports the establishment of a multidisciplinary graduate training program of education and research in urban ecology. Urban ecology is a relatively new endeavor, thus fellows will have unparalleled opportunity to define the field with a diverse group of faculty members, students, and postdocs. Cities are not only important ecosystems to humans but are excellent laboratories for ecological research. The Central Arizona - Phoenix Long-Term Ecological Research project, one of only two urban sites in the NSF's LTER network, provides an established research infrastructure for frontier, multidisciplinary research and graduate training. Training will be built on a collaborative model emphasizing cooperation and teamwork. Fellows may earn degrees in six core departments in the life, earth, and social sciences and will participate in team research, courses, and seminars that emphasize integration among disciplines. Dissertations will be integrative and multidisciplinary and will include a substantial collaborative component beyond the student's home discipline. Collectively, these activities will afford skills that should be broadly applicable to careers in public and private sectors and in academia. The main objective of the program is to educate a new kind of scientist who is broader, more flexible, more collaborative, and more adept at linking science and social issues than heretofore.

IGERT is an NSF-wide program intended to meet the challenges of educating Ph.D. scientists and engineers with the multidisciplinary backgrounds and the technical, professional, and personal skills needed for the career demands of the future. The program is intended to catalyze a cultural change in graduate education by establishing new, innovative models for graduate education and training in a fertile environment for collaborative research that transcends traditional disciplinary boundaries. In the third year of the program, awards are being made to nineteen institutions for programs that collectively span all areas of science and engineering supported by NSF. The intellectual foci of this specific award reside in the Directorates for Biological Sciences, Geosciences, and Education and Human Resources.

Abstract

00-75650
Fisher

Integrating linkages among aquatic and terrestrial landscape elements

This research is designed to determine where in complex landscapes important chemical transformations of various ecological materials occur. Studies will follow water from the time it falls as rain along its path from small rivulets to large streams. These pathways include landscape features such as upland soils, intermittent and permanent streams, and stream side (riparian) zones populated by mature trees. Increases or decreases in materials transported between landscape patches will be related to production, release, or retention within patches. The PIs will perform this research in the Sonoran desert of Arizona, an ecosystem that responds dramatically to variation in climate, especially rainfall and temperature. Emphasis will be on the movement of nitrogen, which is increasing in landscapes worldwide due to human activity. Results of this research will aid in identifying and managing critical ecosystem components for maintenance and enhancement of water quality.

Understanding the response of ecological systems to disturbance is a central
problem in ecology, and is of fundamental importance to management of
ecosystems from local to global scales. Two major theories of disturbance
are stability theory, which describes the rate of return of ecosystems to
pre-disturbance conditions, and multiple state theory, which describes the
transition of ecosystems between alternative equilibrium conditions (e.g.,
grassland vs. shrubland, etc.). Because desert streams are subject to
frequent and severe disturbance in the form of both flood and drying, these
ecosystems provide excellent models for understanding the response of
ecosystems to disturbance more generally. Prior to the end of the 19th
century, wetlands (cienegas) were a common feature of the Southwestern U.S.
Erosion of these wetlands left most arid streams as bare, gravelbed channels
(arroyos) that represent an alternative equilibrium. Recent observations of
wetland re-establishment at a long-term ecological study site (Sycamore
Creek, AZ) provides an opportunity to evaluate how the alternative
configurations of desert streams respond to disturbances using the context
of stability theory. Following flash flood disturbance, we will measure
primary production and ecosystem respiration in both wetland and gravelbed
sites to determine whether these alternative stable states differ in their
response to disturbance. The Intellectual Merit of this proposal lies in
this integration of single- and multiple-equilibrium theories of ecosystem
response to disturbance. The Broader Impact of this research will be to
improve conservation and restoration efforts of this formerly-widespread and
now-rare wetland ecosystem, and to provide opportunities for training of
graduate students in the design, execution, and analysis of ecological
studies.

This integrative Graduate Education and Research Training (IGERT) award supports a multidisciplinary graduate training program of education and research in urban ecology at Arizona State University. The primary study site is Phoenix and central Arizona but both historic (through archeology) and comparative approaches are employed. Intellectual merit. The purpose of the program is to provide doctoral students with enhanced cross disciplinary collaborative training in the natural and social sciences relevant to urban ecology, broadly construed. Training will involve team research through student-originated workshops, interdisciplinary "issues" seminars, dissertation research in urban ecology with an explicitly collaborative component, and an international experience. Broader impacts of the project include close attention to the conduct of research and the engagement of science with law, policy, and the public sphere. Unlike most doctoral programs in the United States that are based on independence, this program will use and investigate the efficacy of interdependence (collaboration, cooperation) as a research mode. The premise is that scientific investigation in important arenas such as cities is increasingly multidisciplinary, yet students commonly receive little direct training or experience in collaborative research strategies and group dynamics necessary for effective communication among disciplines. IGERT is an NSF-wide program intended to meet the challenges of educating U.S. Ph.D. scientists and engineers with the interdisciplinary background, deep knowledge in a chosen discipline, and the technical, professional, and personal skills needed for the career demands of the future. The program is intended to catalyze a cultural change in graduate education by establishing innovative new models for graduate education and training in a fertile environment for collaborative research that transcends traditional disciplinary boundaries.

This project will synthesize a large body of ecological research
from a 27-year study of Sycamore Creek, a desert stream ecosystem in
Arizona. This study has yielded over 120 scientific publications
including a dozen synthetic works. The goal of the project is to bring
together the content of these publications, existing raw data, series of
photographs, and concepts from adjacent disciplines to generate a new
synthesis in the form of a book that will describe the dynamics of
Sycamore Creek and generate an original integration of the fields of
ecosystem science and landscape ecology. The book, along with several
papers in major scientific journals will contribute to our understanding
of creative synthesis in ecology and other realms of science. The
intellectual merit of this project lies in its annealing the disparate
fields of ecosystem and landscape ecology and developing a sound
philosophical view of synthesis in ecology. The broader impacts of this
research include the training graduate students at Arizona State
University to use the perspectives and methods of ecological synthesis
in their own research and future teaching. This combination of research,
teaching, and collaboration will promote and advance the methodology of
synthesis in science.