Category: General Publications
Title: Postsettlement Changes in Natural Fire Regimes and Forest Structure: Ecological Restoration of Old-Growth Ponderosa Pine Forests
Author: * Covington, W.W., Moore, M.M.
Subject: Ecological Restoration, Post-settlement
Abstract: Heavy livestock grazing, logging, and fire exclusion associated with Euro-American settlement has brought about substantial changes. in forest conditions in western forests. Thus, oldgrowth 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 mortalityfrom 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 win 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.
Source: Ecological and Historical Perspectives
Publisher: The Haworth Press, Inc.