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Title: RESTORATION OF ASPEN WOODLAND INVADED BY WESTERN JUNIPER: APPLICATIONS OF PARTIAL CUTTING AND PRESCRIBED FIRE

Author
item Bates, Jonathan - Jon
item MILLER, RICHARD - OREGON STATE UNIV

Submitted to: Society for Ecological Restoration Abstracts
Publication Type: Proceedings
Publication Acceptance Date: 6/1/2004
Publication Date: 8/26/2004
Citation: Bates, J.D., Miller, R.F. 2004. Restoration of aspen woodland invaded by western juniper: applications of partial cutting and prescribed fire. In: Proceedings of the 16th Int'l Conferences, Society for Ecological Restoration, August 24-26, 2004, Victoria, Canada. 2004 CDROM.

Interpretive Summary: Western juniper (Juniperus occidentalis spp. occidentalis) woodlands are rapidly replacing quaking aspen (Populus tremuloides) stands throughout the northern Great Basin. Aspen stands provide important habitat for many wildlife species and contain a high diversity of understory shrubs and herbaceous species. We studied two juniper removal treatments to restore aspen woodlands in Kiger Canyon on Steens Mountain, Oregon. Treatments included cutting 1/3 of the juniper trees followed by: 1) early fall burning (FALL); and 2) early spring burning (SPRING). Because of lack of fuels and high fuel moisture content partial cutting of juniper was done to create a fuels base to carry fire through woodlands. The project has evaluated 1) the effectiveness of treatments at removing juniper from seedlings to mature trees, 2) monitored aspen recruitment, and 3) measured recovery of shrub and herbaceous cover and diversity. Fall burning eliminated all remaining juniper trees and seedlings, but understory cover and diversity were reduced significantly. By the second year after fire, aspen suckering in the FALL treatment averaged 12,000/ha. Spring burning produced a less intense fire, removing 80% of the mature juniper trees that remained after cutting. However, about 50% of the juniper seedlings survived in the SPRING treatment. Aspen suckering in the SPRING was only 4,000/ha but the understory remained largely intact and herbaceous cover and diversity increased. In conclusion, if the objective is to eliminate western juniper, with minimal cutting, and stimulate greater aspen suckering then we recommend woodlands be fall burned. If the objective is to maintain shrub and herbaceous layers, marginally increase aspen suckering, and retain a few mature junipers in the community, then spring burning is recommended.

Technical Abstract: Western juniper (Juniperus occidentalis spp. occidentalis) woodlands are rapidly replacing quaking aspen (Populus tremuloides) stands throughout the northern Great Basin. Aspen stands provide important habitat for many wildlife species and contain a high diversity of understory shrubs and herbaceous species. We studied two juniper removal treatments to restore aspen woodlands in Kiger Canyon on Steens Mountain, Oregon. Treatments included cutting 1/3 of the juniper trees followed by: 1) early fall burning (FALL); and 2) early spring burning (SPRING). Because of lack of fuels and high fuel moisture content partial cutting of juniper was done to create a fuels base to carry fire through woodlands. The project has evaluated 1) the effectiveness of treatments at removing juniper from seedlings to mature trees, 2) monitored aspen recruitment, and 3) measured recovery of shrub and herbaceous cover and diversity. Fall burning eliminated all remaining juniper trees and seedlings, but understory cover and diversity were reduced significantly. By the second year after fire, aspen suckering in the FALL treatment averaged 12,000/ha. Spring burning produced a less intense fire, removing 80% of the mature juniper trees that remained after cutting. However, about 50% of the juniper seedlings survived in the SPRING treatment. Aspen suckering in the SPRING was only 4,000/ha but the understory remained largely intact and herbaceous cover and diversity increased. In conclusion, if the objective is to eliminate western juniper, with minimal cutting, and stimulate greater aspen suckering then we recommend woodlands be fall burned. If the objective is to maintain shrub and herbaceous layers, marginally increase aspen suckering, and retain a few mature junipers in the community, then spring burning is recommended.