Forest changes since Euro-American settlement and ecosystem restoration in the Lake Tahoe Basin, USA

Abstract

Pre Euro-American settlement forest structure and fire regimes for Jeffrey pine-white fir, red fir-western white pine, and lodgepole pine forests were quantified using stumps from trees cut in the 19^th century to establish a baseline reference for ecosystem management in the Lake Tahoe Basin. Contemporary forests varied in different ways compared to the presettlement reference. Contemporary Jeffrey pine-white fir forests have more and smaller trees, more basal area, less structural variability, and trees with a more clumped spatial distribution than presettlement forests. The mean presettlement fire return interval for the period 1450-1850 for Jeffrey pine-white fir forests was 11.5 years, and most fires (>90 percent) burned in the dormant season, while no fire was recorded in the study area after 1871. Differences in the structural characteristics of contemporary and presettlement red fir-western white pine and lodgepole pine forests were similar to those for Jeffrey pine-white fir forests. However, 19^th century logging changed the composition of red fir-western white pine forests, and these forests now have more lodgepole pine than red fir or western white pine. Comparison of contemporary Jeffrey pine-white fir forests with the presettlement reference suggest that restoration treatments should include: (1) density and basal area reduction, primarily of smaller diameter trees, (2) reintroduction of frequent fire as a key regulating disturbance process, and (3) increasing structural heterogeneity by shifting clumped tree distributions to a more random pattern. Restoration treatments in red fir-western white pine forests should include: (1) a shift in species composition by a density and basal area reduction of lodgepole pine, and (2) increasing structural heterogeneity by shifting tree distributions to a more random pattern. In lodgepole pine forests, the restoration emphasis should be: (1) a density and basal area reduction of small diameter trees, and (2) an increase in structural heterogeneity that shifts tree spatial patterns from clumped to a more random distribution. Reintroduction of fire as a regulating process into high elevation red fir-western white pine and lodgepole pine forests may be viewed as a long-term restoration goal.

Parent Publication

• Restoring fire-adapted ecosystems: proceedings of the 2005 national silviculture workshop

Citation

Taylor, Alan H. 2007. Forest changes since Euro-American settlement and ecosystem restoration in the Lake Tahoe Basin, USA. In: Powers, Robert F., tech. editor. Restoring fire-adapted ecosystems: proceedings of the 2005 national silviculture workshop. Gen. Tech. Rep. PSW-GTR-203, Albany, CA: Pacific Southwest Research Station, Forest Service, U.S. Department of Agriculture: 3-20