USDA Forest Service

Pacific Southwest Research Station
Pacific Southwest
Research Station

800 Buchanan Street
Albany, CA 94710-0011
(510) 883-8830
United States Department of Agriculture Forest Service. USDA logo which links to the department's national site. Forest Service logo which links to the agency's national site.

Research Topics Ecosystem Processes

Sierra Nevada Ecosystems

Role of Urban Forests in Conserving and Restoring Biological Diversity in the Lake Tahoe Basin

Study Plan
Research Project Summary

The Research

The conversion of wildlands to buildings, roads, and other developments results in habitat loss and the fragmentation of associated landscapes. Landscape fragmentation has three primary components: loss of original habitat, reduction in habitat patch sizes, and increasing isolation of habitat patches -- all of which contribute to a decline in biological diversity within the original habitat. Landscape fragmentation has a progressive and erosive effect on biological diversity and integrity, however our understanding of how disturbance and fragmentation influence the distribution and abundance of organisms is inadequate to effectively manage to sustain populations in the face of fragmentation.


blue arrrow To determine the effects of fragmentation and disturbance on the occurrence, abundance, composition, and productivity of vertebrates, vascular plants and select invertebrate species in an urbanizing landscape.
blue arrrowTo evaluate the potential for landscape-level thresholds of species persistence for select focal species based on the amount, distribution and quality of habitat.
blue arrrowTo investigate the validity of species expected to be strong indicators based on intrinsic characteristics based on empirical data.
blue arrrowTo develop a predictive model that evaluates the relative effects of various acquisition, restoration, and development scenarios on individual species, species groups, and biological diversity.

Methods and Design

This project investigates the effects of patch-scale relationships between patch size, isolation, and disturbance and the associated species composition, abundance, and productivity of birds, mammals, vascular plant, and select invertebrates. We are sampling 100 sites along a development gradient within the lower montane zone around Lake Tahoe. Many data collection techniques are used to characterize the composition and abundance of vertebrate, ant, and plant species. Specifically, we are sampling landbirds (point counts and nest monitoring), small mammals (live trapping), large mammals (trackplate and camera stations), ants (pitfall traps and nest counts), and plants (many field techniques). Data are being collected in 2003-2005, with final analysis and results available by the end of 2006.

Application of Research Results

The following management objectives will be addressed:

1. What are reliable criteria for identifying potential indicator species?
2. Do particular species, species groups, or environmental parameters emerge as strong indicators of biological integrity at the stand or landscape scales?
3. How does anthropogenic disturbance within and around urban lots affect the ability of urban lots to support their native diversity of species? What management options exist for reducing the negative effects of disturbance?
4. What role do urban lots play in supporting biological integrity at the landscape scale? How might that role shift in light of various development (i.e., build-out) scenarios within the basin?
5. What management options exist for improving the biological integrity of existing urban lots?
6. What are the predicted effects of various stand and landscape-scale management scenarios regarding urban lot management (i.e., development, acquisition, restoration)?

map of the Sierra Nevada Ecoregion

The study area is the Lake Tahoe basin, located on the California-Nevada border in the central Sierra Nevada. The Lake Tahoe basin is an ideal setting to study of the contribution of forested parcels to maintaining biological diversity and integrity of a larger urbanizing landscape. The majority of development is restricted to the lower elevation areas around Lake Tahoe, and many species of vertebrates and vascular plants are most closely associated with these habitats. For these low elevation associates, the high elevation crests surrounding the basin are likely be an impediment to their dispersal, creating closed populations that are particularly vulnerable to fragmentation and disturbance.

Lead Scientists/Collaborators

1) Manley, Patricia N., 2)Murphy, Dennis D., 1) Campbell, Lori, 1,3) Schlesinger, Matthew D., 3) Holyoak, Marcel, 2) Merideth, Susan, 2) Arsenault, David, and 2) Sanford, Monte

1 USDA Forest Service
Sierra Nevada Research Center
2121 Second St., Suite A-101
Davis, CA 95616
ph: (703)-605-5294

2 University of Nevada
Department of Biology
Reno, Nevada 89557

3 University of California
Department of Ecology
Davis, CA 95616

Publications and Products

Parks, S.A., L.A. Campbell, P.N. Manley, and M.D. Schlesinger. In review. Modeling development as a continuum to address fine-grained heterogeneity in urbanizing landscapes. Ecological Applications.

Manley, P. N., D. D. Murphy, L. A. Campbell, K. E. Heckmann, S. Merideth, M. Sanford, and M. D. Schlesinger. 2005. Biotic diversity interfaces with urbanization in the Lake Tahoe basin. California Agriculture 60(2):59-64.

Manley, P. N. and D. D. Murphy. 2004. Roles of urban forests in conserving and restoring biological diversity in the Lake Tahoe basin: Interim Report 2003. Unpublished report. USDA Forest Service, Lake Tahoe Basin Management Unit, South Lake Tahoe, CA.

Manley, P. N. and D. D. Murphy. 2004. Roles of urban forests in conserving and restoring biological diversity in the Lake Tahoe basin: Interim Report 2004. Unpublished report. USDA Forest Service, Lake Tahoe Basin Management Unit, South Lake Tahoe, CA.

Last Modified: Aug 29, 2016 10:56:37 AM