USGS identifier

Science Goals

Goal 5--Establish the geologic framework for ecosystem structure and function

Human population growth and economic development are strong forces that drive land-use decisions and have the potential to alter the distribution, structure, function, and health of ecosystems. As this development proceeds, however, the importance of healthy and diverse ecosystems to the quality of human life is becoming widely recognized and more highly valued by the public (see table 1). In the face of human modifications to ecosystems, resource managers must develop and implement ecosystem management strategies that conserve biological diversity, restore degraded habitats, facilitate sustainable plant and animal harvests, control invasive species, and maintain water quality. The USGS, as the Nation's earth science and biological science agency, will assist ecosystem managers by providing the essential scientific information needed to make wise land-use decisions.

The scientific basis for ecosystem management, particularly the role of geology in sustaining or restoring ecosystems, is emerging as a major, multidisciplinary scientific challenge for the GD. It is now widely recognized that the living resources of ecosystems have a spatial organization imposed upon them by the geologic framework of the region and that geologic processes (for example, sediment transport, soil formation, ground-water flow) significantly influence ecosystem evolution and vitality on time scales of days to decades. Moreover, the geologic record contains valuable clues to the structure, history, and behavior of ecosystems.

GD geologists will work with biologists, ecologists, hydrologists, and chemists to characterize the geologic framework and hydrologic cycle of ecosystems and to identify the geological and geochemical processes critical to ecosystem structure, function, and restoration. The temporal focus will be on time scales of agricultural, industrial, and urban development to provide the scientific understanding necessary for management of ecosystem health, sustainability, and restoration. GD geoscience studies of ecosystems will be concentrated in rapidly urbanizing areas, coastal zones, public lands, and other regions of national importance or interest such as the Florida Everglades (see Highlight 12), the Mojave Desert, the North Slope of Alaska, the Rocky Mountain Front Range Urban Zone, and the Chesapeake Bay region.


Maps of surficial and shallow-subsurface lithologic, mechanical, and geochemical properties of ecological significance for selected ecosystems.
For example, the GD will prepare maps of cryptogamic soils (lichen and blue-green algal encrusted soils), found in some desert regions; these maps can aid land managers in devising proper land-use policies by highlighting areas vulnerable to overgrazing. When disturbed, cryptogamic soils become susceptible to erosion, resulting in loss of vital soil and invasion of non-native plants.

Models of geologic and geochemical processes that affect ecosystem functions.
The GD will develop models that can be used to anticipate changes in those portions of the ecosystem linked to geologic phenomena. For example, the dynamics of coastal barrier islands and lagoons and nutrient cycling in wetlands can be modeled to provide forecasts of vegetative change due to both natural variability and human disruption.

Geochemical baselines of metals and other contaminants.
The GD will document predevelopment background variability in minor- and trace-element chemistry and subsequent change during human occupation. Baselines are most easily developed in areas of rapid change, but in mature urban areas, geologic records may be derived from sediments in lakes, reservoirs, and estuaries. Paleobiological records, such as those derived from tree rings or annually banded corals, may also be available in some settings. Activities associated with these products have strong links with Goal 6 and complement efforts in other USGS divisions and other Federal agencies such as the EPA and NOAA.

Rates of faunal and floral change during recent geologic history determined from paleontological and geochemical studies.
The GD studies will support landscape, ecological, and climate modeling. Landscape models used to predict faunal and floral change are constructed, in part, from empirically determined rates of landscape processes such as plant succession. In the Everglades, for example, analyses of pollen from well-dated peat cores provide the best estimates of the rate of replacement of sawgrass by mangroves. Time scales for these products will generally be more recent than those for Goal 4, but strong links must be made in order to separate natural transitions from human-induced alterations.

Assessments of fundamental geologic fluxes that affect ecosystem dynamics.
The GD will study geological fluxes, including the roles of sedimentation and erosion, soil and dust generation, and other surficial processes, in maintaining or degrading sensitive ecosystems (for example, tundra, western and desert soils, and coral reefs). Develop partnerships with scientists outside the GD.

For example, GD scientists will collaborate with ecologists, hydrologists, and microbiologists in interdisciplinary teams to study the controls of ecosystem dynamics and the potential for ecosystem restoration.

Strategic Actions

Focus geologic mapping of both bedrock and surficial deposits in ecosystem gradients.
Ecosystem gradients are regions where human needs for development and use of natural resources are competing directly with the need for preservation. These areas will occur primarily along the margins of rapidly urbanizing areas, in coastal zones, and on public, multiuse lands.

Determine rates of floral, faunal, and other environmental changes.
By using stratigraphy, paleontology, sedimentology, soil science, geochemistry, and high-resolution geochronology, GD scientists can determine rates of change to provide information on ecosystem development and history.

Conduct fundamental research to understand the roles of surface geology and geomorphology and surficial geologic processes.
GD studies of bedrock, slope stability, soil formation, and sediment transport and deposition will aid in understanding the structure and function of natural ecosystems.

Investigate biogeochemical cycles in ecosystems focusing on the sediment-soil interface and on elemental pathways.
GD scientists will study the carbon, nitrogen, sulfur, and phosphorus cycles using trace-element and isotopic tracers and will investigate the role of microbes in soil formation.

<----- Back to Contents || Back to Goal 4 || Continue to Goal 6 ----->

This page is <>
Maintained by L. McElroy
Last updated 04.08.98