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.

Programs and Projects


Ecology and Management of Western Forests Influenced by Mediterranean Climate

The Management Impacts on Forest Vegetation Research Team's emphasis is to develop a better understanding of the impact of forest management practices on the composition, structure, and growth of forest vegetation.

The need to balance resource use with future forest health and sustainability calls for improved understanding of the effects of forest management practices. Forest composition, structure, and growth can be significantly altered by manipulating early spacing, competing vegetation, fertilization, and stand density (thinning). The research base for describing the relationships between forest management options and silvicultural practices for forest trees and stands is well developed. Similar support and the research data base for tree response to competing vegetation and development of all vegetation components, whether in response to silvicultural practices or by natural processes, is in its infancy. Also, uncertainty exits as to how common silvicultural practices affect biodiversity and ecosystem sustainability.

More specifically, we need more information on the species composition of the plant community that ensues after natural and human-caused disturbance. The autecology of many shrubs, forbs, and grasses, and their density, development, phenology, onset of seed production, and frequency and magnitude of seed crops is virtually unknown. The developmental dynamics of native California hardwoods is especially lacking.

Societal interest in maintaining and increasing late successional habitat for wildlife and aesthetics has added new goals and objectives for silviculture. Our knowledge of the response of vegetation to silvicultural practices designed to enhance timber production leads us to believe that imaginative use of the same practices can help manintain existing late successional forests and can accelerate the development of late successional chacracteristics in young-growth forests. On-the-ground examples of such silvicultural strategies do not exist. Particularly absent are intermediate term (20-60 years) data on plant composition and dynamics as well as methods necessary to attain desired amounts of vegetation and its structure for codominant and intermediate crown classes.

Emphasis is placed on the effort to quantify conifer, hardwood, shrub, forb, and grass density and development in different disturbance regimes and tie these results to early, intermediate and late successional stages. Other areas of research include:

  • Testing methods to maintain and enhance existing late successional stands. Various partial harvesting schemes are being tested along with prescribed fire in the Blacks Mountain Interdisciplinary Research Project (link) in eastside pine.
  • Determining how to accelerate development of stand structures in young forests toward late successional characteristics. An interdisciplinary study on the Goosenest Adaptive Management Area (link) is testing three pathways to late successional attributes in 80-year-old mixed conifers. 
  • Model growth dynamics for forest components other than commercial timber trees, such as shrubs, non-commercial species of trees, snags, and partial harvests on a landscape scale. 
  • Development of models for traditional growth and yield projection systems for ponderosa pine and true firs based on existing data from long-term permanent plots in managed stands. Significant improvements are expected because existing simulators based on temporary plots in unmanaged stands do not accurately project observed responses to many silvicultural treatments.
Research Scientists

Martin W. Ritchie, Biometrician & Team Leader
William W. Oliver, Emeritus Research Forester
Phillip M. McDonald, Emeritus Research Forester
Jianwei Zhang, Research Forester

Research Staff

Todd A. Hamilton, Forestry Technician
Brian M. Wing, Forestry Technician

Research Projects
Blacks Mountain Ecological Research Project
Little Horse Peak (Goosenest AMA) Research Project
Growth and Yield Simulation (CONIFERS)
Last Modified: Mar 13, 2007 06:15:25 AM