Effects of forest management on soil C and N storage: meta analysis

The effects of forest management on soil carbon (C) and nitrogen (N) are im portant to understand not only because these are often master variables det ermining soil fertility but also because of the role of soils as a source o r sink for C on a global scale. This paper reviews the literature on forest management effects on soil C and N and reports the results of a meta analy sis of these data. The meta analysis showed that forest harvesting, on aver age, had little or no effect on soil C and N. Significant effects of harves t type and species were noted, with sawlog harvesting causing increases (+1 8%) in soil C and N and whole-tree harvesting causing decreases (-6%). The positive effect of sawlog harvesting appeared to be restricted to coniferou s species. Fire resulted in no significant overall effects of fire on eithe r C or N (when categories were combined); but there was a significant effec t of time since fire, with an increase in both soil C and N after 10 years (compared to controls). Significant differences among fire treatments were found, with the counterintuitive result of lower soil C following prescribe d fire and higher soil C following wildfire. The latter is attributed to th e sequestration of charcoal and recalcitrant, hydrophobic organic matter an d to the effects of naturally invading, post-fire, N-fixing vegetation. Bot h fertilization and N-fixing vegetation caused marked overall increases in soil C and N. (C) 2001 Elsevier Science B.V. All rights reserved.