Coarse woody debris following fire and logging in Wyoming lodgepole pine forests

The accumulation and decomposition of coarse woody debris (CWD) are process es that affect habitat, soil structure and organic matter inputs, and energ y and nutrient flows in forest ecosystems. Natural disturbances such as fir es typically produce large quantities of CWD as trees fall and break, where as human disturbances such as timber harvesting remove much of the CWD. Our objective to compare the amount of CWD removed and left behind after clear -cutting to the amount consumed and left behind after natural fires in Rock y Mountain lodgepole pine. The masses of fallen logs, dead-standing trees, stumps, and root crowns more than 7.5 cm in diameter were estimated in clea r-cut and intact lodgepole pine forests in Wyoming and compared to estimate s made in burned and unburned stands in Yellowstone National Park (YNP), wh ere no timber harvesting has occurred. Estimates of downed CWD consumed or converted to charcoal during an intense crown lire were also made in YNP. N o significant differences in biomass of downed CWD more than 7.5 cm in diam eter were detected between burned stands and those following a single clear -cut. However, the total mass of downed CWD plus the mass of snags that wil l become CWD was nearly twice as high in burned stands than in clear-cuts. In YNP, approximately 8% of the downed CWD was consumed by fire and an addi tional 8% was converted to charcoal, for an estimated loss of about 16%. In contrast, approximately four times more wood (70%) was removed by clear-cu tting. Considering all CWD more than 7.5 cm in diameter that was either sti ll present in the stand or removed by harvesting, slash treatment, or burni ng, clear-cut stands lost an average of 80 Mg ha(-1) whereas stands that bu rned gained an average of 95 Mg ha(-1). Some CWD remains as slash and stump s left behind after harvesting, but stands subjected to repeated harvesting will have forest floor and surface soil characteristics that are beyond th e historic range of variability of naturally developing stands.