Stuart Hargraft Gage - US grants

An understanding of the influence of local landscape structure on insect population dynamics is critically needed to address questions concerning agro-ecosytem re-design. An in depth examination of specific alfalfa herbivores and predators in a diverse ecological-agricultural landscape is proposed. A Geographic Information System (GIS) will be employed as the principal analytical tool in establishing relationships between landscape complexity and insects. The following objectives are proposed: characterize local ecosytems wide distribution of predaceous coccinellids, aphid prey and leafhopper migrants as colonization of alfalfa begins; quantify microclimate factors which influence insect development in and dispersal from over- wintering sites to spring habitats; measure and determine the effect of landscape structural diversity on initial colonization of alfalfa by insect predators and pests, and the recolonization of alfalfa following disturbance associated with alfalfa cutting and harvest. These results will be used in a GIS assessment of landscape effects on insect dynamics. This research will provide essential information on predator/prey dynamics across landscapes.

In 1987 a Long-Term Ecological Research Project in Agricultural Ecology was initiated to examine basic ecological relationships in row crop ecosystems typical of the U.S. Midwest. The project's original goal was to test the basic, long-term hypothesis that agronomic management based on knowledge of ecological interactions in cropping systems can effectively replace management based on chemical subsidies. The same overall goal guides the project today. In order to test this hypothesis an experimental site was established in which different cropping systems, corresponding to different levels of agronomic/ecological disturbance, are used to test a series of working hypotheses. Working hypotheses are built around the general topic areas of nutrient availability/ retention, plant competition, and consumer (insect, pathogen) dynamics. Over the initial award period substantial progress has been made towards meeting the short-term goals of establishing a secure agricultural research site with long-term potential, of putting in place an integrated sampling program to address important long-term questions in both ecology and agronomy, and most importantly, of testing and refining the initial hypotheses. In this new project period the aim is to extend plot-based research to the regional landscape and to address seven basic ecological hypotheses that are critical for understanding the ecological underpinnings of modern agriculture and for providing the knowledge needed to sustain future agricultural production.

As early as 1962 Rachel Carson recognized the need for biological solutions to environmental problems. She said: "A truly extraordinary variety of alternatives to the chemical control of insects is available. Some are already in use... others are little more than ideas in the minds of imaginative scientists,... . All have this in common: they are biological solutions, based on the living organism they wish to control, and to the whole fabric of life to which these organisms belong. This research project will work within this context to develop natural alternatives to pesticide and herbicides as crop-land management tools. The long-term goal of our research is to understand the behavior of insects that ate natural predators on pests that reduce the productivity of agricultural crops. We will identify attributes of the landscape that are favored by a predator on aphids, the ladybird beetles. This knowledge could allow us to naturally reduce the number of insect pests by designing an agricultural landscape that promotes a large population of predators. The first step in this research is to define the link between various crop types and the predatory insect. This is done by determining if there is a match between the abundance of naturally occurring stable isotopes of carbon and nitrogen in the insect predators and the agricultural crop. A future step will be to link the spatial distribution of the predators with respect to landscape elements. These two steps are a unique approach to studying the behavior of insects because they combine technology from geology and chemistry (analysis of naturally occurring stable isotopes), entomology (insect population dynamics, biological control), and geography (landscape mapping using geographical information systems).

9810220
Robertson

Agricultural activities worldwide are carried out through a combination of biological and chemical management practices. The Kellogg Biological Station (KBS) Long-Term Ecological Research program has been conducting research since 1987 focusing on testing the hypothesis that agronomic management practices based on knowledge of ecological interactions can effectively replace management based on chemical subsidies. Work to test this general hypothesis is focused on field-crop ecosystems that are used extensively throughout the US Midwest. KBS research employs a series of sites where 11 different cropping systems and successional communities have been established to represent different levels and types of ecological disturbance. Within this series of sites, working hypotheses are being tested in general areas of soil microbial communities, the dynamics of insect consumers, nutrient availability, and plant community dynamics.
Recent work has led to development of biologically based agricultural systems that produce acceptable crop yields. The KBS site has documented changes in abundance of various taxa that appear to be important in row-crop function and in ecosystem-level attributes of agricultural systems. General ecological understanding has been advanced in key relationships in field-crop ecosystems. In addition to continuing these efforts, proposed work will evaluate the effects of agricultural practices at scales larger than individual fields on the dynamics of biogeochemical processes in entire watersheds. Efforts will also be developed to incorporate a social component to evaluate the degree to which human decision making plays critical roles in the ecological processes occurring in agricultural ecosystems. Finally, the results of efforts at the KBS site will be regionalized to develop a general understanding of the interactions between climate and productivity across the entire North Central Region.

Initiated in 1987, the Kellogg Biological Station LTER (KBS) examines basic ecological relationships in field crop ecosystems to better understand internal processes controlling productivity independently of external subsidies (e.g., fertilizers, pesticides). The initial goal remains the same: effectively substituting ecological knowledge and theory in the agronomic management of cropping systems for a reliance on chemically based approaches. Research involves synergistic activities of long-term observations of contrasting cropping systems and successional vegetation, shorter-term field experiments, and modeling. Hypothesis testing relates to patterns and processes underlying ecosystem productivity and nutrient retention, including plant community dynamics, soil microbial populations, insect consumer dynamics, watershed and field-scale biogeochemistry, human interactions, and regional processes. KBS-4 is organized around the same initial hypothesis, albeit with a new conceptual research model and the addition of a new focus on valuation of ecosystem services. The model organizes ecological understanding of field crop ecosystems into components focused on ecological structure (e.g., organisms and their adaptations, population and community assemblages, and habitat structure) vis a vis ecological functions (e.g., biogeochemical processes, energy capture and flow, and hydrodynamics). Linkages between these components largely define the mechanisms that underlie the production of ecosystem goods and services, those products that provide the economic and social rationale for farming. Major research topics include plant community change, microbial processes, controls of arthropod communities, biogeochemical fluxes of solutes and trace gases, human valuation of cropland ecosystem services, and regionalization (scaling up via models).

Broader Impacts. KBS is an established leader in developing and using ecological approaches to improving our understanding of agroecosystems. KBS research deals with food production, a topic of global significance, and has ready practical applications to the ongoing development of mid-western US agriculture, as well as the potential to make significant contributions to the more general area of sustainable agriculture. Outreach and educational activities are robust at KBS. Research findings are reaching the media, local and regional agricultural communities, and other key citizen groups influencing land management. KBS places a high priority on connections with agricultural policymaking and global-change issues. Several KBS scientists have testified to Congress on agricultural issues and strong international connections have been forged. The site has a significant on-the-ground outreach program offering a wide range of service and educational opportunities to the broader community including agricultural extension services, informal education, university coursework, research experience for undergraduate and graduate students, and Schoolyard LTER activities for K-12 students and educators. Contributions to the LTER network include the publication of a soils methods synthesis book and participation in the diversity x NPP and LINX network-wide studies. The site is close to full adoption of the Ecological Meta-Language (EML2) format standard to ensure easy data exchange.