首页   按字顺浏览 期刊浏览 卷期浏览 Postsettlement Changes in Natural Fire Regimes and Forest Structure
Postsettlement Changes in Natural Fire Regimes and Forest Structure

 

作者: W.W. Covington,   M.M. Moore,  

 

期刊: Journal of Sustainable Forestry  (Taylor Available online 1994)
卷期: Volume 2, issue 1-2  

页码: 153-181

 

ISSN:1054-9811

 

年代: 1994

 

DOI:10.1300/J091v02n01_07

 

出版商: Taylor & Francis Group

 

数据来源: Taylor

 

摘要:

Heavy livestock grazing, logging, and fire exclusion associated with Euro-American settlement has brought about substantial changes in forest conditions in western forests. Thus, old-growth definitions based on current forest conditions may not be compatible with the natural conditions prevalent throughout the evolutionary history of western forest types. Detailed analysis of data from two study areas in the southwestern ponderosa pine type suggests that average tree densities have increased from as few as 23 trees per acre in presettlement times to as many as 851 trees per acre today. Associated with these increases in tree density are increases in canopy closure, vertical fuel continuity, and surface fuel loadings resulting in fire hazards over large areas never reached before settlement. In addition, fire exclusion and increased tree density has likely decreased tree vigor (increasing mortality from disease, insect, drought, etc.), herbaceous and shrub production, aesthetic values, water availability and runoff, and nutrient availability, and also changed soil characteristics and altered wildlife habitat. To remedy these problems and restore these forest ecosystems to more nearly natural conditions, and maintain a viable cohort of old age-class trees, it will be necessary to thin out most of the postsettlement trees, manually remove heavy fuels from the base of large, old trees, and reintroduce periodic burning.

 

点击下载:  PDF (867KB)



返 回