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Submitted to: Extension Reports
Publication Type: Experiment Station Publication Acceptance Date: 5/1/2008 Publication Date: 6/1/2008 Citation: Bates, J.D., Davies, K.W. 2008. Restoration of quaking aspen woodlands invaded by western juniper. Extension Reports. Range Field Day 2008 Progress Report. Oregon State University Agricultural Experiment Station, Special Report 1085. Burns, OR. pp. 86-92. Interpretive Summary: Quaking aspen woodlands are important plant communities in the interior mountains of the western United States, providing essential habitat for many wildlife species and contain a high diversity of understory plants. Western juniper woodlands are rapidly replacing lower elevation (<6800 ft) quaking aspen stands throughout the northern Great Basin as a result of fire exclusion. The purpose of this research was to evaluate two juniper control treatments for restoring aspen stands in eastern Oregon using selective cutting and prescribed fire. The juniper control treatments involved cutting 1/3 of mature juniper trees followed by: 1) early fall burning (FALL); or 2) early spring burning (SPRING). Research objectives were: 1) test the effectiveness of treatments at removing juniper from seedlings to mature trees, 2) measure treatment effectiveness at stimulating aspen recruitment, and 3) evaluate the response of shrub and understory plants to treatment. Cutting combined with fall fire was the most effective method at removing remaining juniper and stimulating greater aspen suckering. Fall fire severely impacted the understory and reseeding of herbaceous perennials should be considered. Native perennial forbs and grasses were largely eliminated with the fall fire. In these lower elevation aspen stands non-native weeds appear to be of concern in early succession as they rapidly increase before native perennials can reestablish. Cutting combined with spring burning provides only a temporary interruption of the development to juniper woodland. Gaps created by the cutting and fire disturbance will provide juniper saplings and seedlings with the opportunity to reoccupy the SPRING sites. However, if management objectives are to increase the herbaceous component and moderately increase aspen suckering, spring burning is recommended. Herbaceous cover increased 330%, no mortality of bunchgrasses occurred, and the number of species observed increased by 50% by the fifth year after fire. An advantage of spring burning is that the fire can be confined to the treatment area without much risk of escape, thus this method may be useful in more forested systems. Technical Abstract: Quaking aspen woodlands are important plant communities in the interior mountains of the western United States, providing essential habitat for many wildlife species and contain a high diversity of understory plants. Western juniper woodlands are rapidly replacing lower elevation (<6800 ft) quaking aspen stands throughout the northern Great Basin as a result of fire exclusion. The purpose of this research was to evaluate two juniper control treatments for restoring aspen stands in eastern Oregon using selective cutting and prescribed fire. The juniper control treatments involved cutting 1/3 of mature juniper trees followed by: 1) early fall burning (FALL); or 2) early spring burning (SPRING). Research objectives were: 1) test the effectiveness of treatments at removing juniper from seedlings to mature trees, 2) measure treatment effectiveness at stimulating aspen recruitment, and 3) evaluate the response of shrub and understory plants to treatment. Cutting combined with fall fire was the most effective method at removing remaining juniper and stimulating greater aspen suckering. Fall fire severely impacted the understory and reseeding of herbaceous perennials should be considered. Native perennial forbs and grasses were largely eliminated with the fall fire. In these lower elevation aspen stands non-native weeds appear to be of concern in early succession as they rapidly increase before native perennials can reestablish. Cutting combined with spring burning provides only a temporary interruption of the development to juniper woodland. Gaps created by the cutting and fire disturbance will provide juniper saplings and seedlings with the opportunity to reoccupy the SPRING sites. However, if management objectives are to increase the herbaceous component and moderately increase aspen suckering, spring burning is recommended. Herbaceous cover increased 330%, no mortality of bunchgrasses occurred, and the number of species observed increased by 50% by the fifth year after fire. An advantage of spring burning is that the fire can be confined to the treatment area without much risk of escape, thus this method may be useful in more forested systems. |
