Impacts of management on forest floor and soil organic carbon stocks in northern forests

While interest in forest carbon sequestration continues to grow, few studies have been conducted specifically to address the effects of common forest management practices on forest floor and soil carbon pools.  This project measured forest floor and soil organic carbon stocks in treated and untreated plots from seven long-term forest management experiments in six northern states; treatments vary across sites and range from clearcuts to light thinnings.  This study has two main objectives, the first of which is to investigate the effects of thinning and harvesting treatments on forest floor and mineral soil carbon pools in these long-term studies.  The second is to obtain estimates of forest floor and soil carbon stocks from the untreated plots, to serve as benchmarks and provide an opportunity to search for underlying patterns or trends on which to base generalized estimates.  No significant effects attributable to management treatments were detected at any of the study sites; soil carbon stocks in the upper 20 cm of mineral soil in untreated plots vary from 28-70 tC/ha with most sites between 37-62 tC/ha.  The %C of the forest floor averages 41.5% and is not significantly different across sites, or between treated and untreated plots.  No differences in forest floor carbon pool estimates were detected between treated and untreated plots; carbon stocks in the forest floor of untreated plots range from 2.4 to 18.1 tC/ha with the majority of sites containing 8-14 tC/ha.