9322706 Covington This research has two primary objectives: (1) to determine changes in selected ecosystem characteristics of a southwestern ponderosa pine/bunchgrass ecosystem since Euro-American settlement, and (2) to determine changes in these same characteristics after two restoration treatments. Trees, shrubs, herbaceous vegetation, coarse woody debris and forest floor will be mapped on plots in two study areas. These data will be used in conjunction with dendroecological analysis and ecological simulation to estimate post-settlement changes in aboveground biomass, primary production, decomposition, microbial functional groups, nutrient cycling characteristics, and old growth tree physiology and susceptibility to insect attacks. Experimental treatments include (1) Control, (2) complete restoration (thin postsettlement trees, remove forest floor, burn at natural burning intervals), and (3) partial restoration (thin postsettlement trees). Previous research has shown that introducing fire without first removing forest floor materials results in death of overstory trees and damage to belowground systems. %%% This research will further our understanding of the role of fire in ecosystem restoration in southwestern forest systems. In addition to clear management implications, this research will enhance our understanding of the interaction of net primary production, fire, decomposition, microbial functional groups, and nutrient cycling in controlling ecosystem structure and function, and enhance knowledge of the role of natural disturbance regimes in forest ecosystems. ***
