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 important to understand not only because these are often master variables determining soil fertility but also because of the role of soils as a source or 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 analysis of these data. The meta analysis showed that forest harvesting, on average, had little or no effect on soil C and N. Signi®cant effects of harvest type and species were noted, with sawlog harvesting causing increases (‡18%) in soil C and N and wholetree harvesting causing decreases (ÿ6%). The positive effect of sawlog harvesting appeared to be restricted to coniferous species. Fire resulted in no signi®cant overall effects of ®re on either C or N (when categories were combined); but there was a signi®cant effect of time since ®re, with an increase in both soil C and N after 10 years (compared to controls). Signi®cant differences among ®re treatments were found, with the counterintuitive result of lower soil C following prescribed ®re and higher soil C following wild®re. The latter is attributed to the sequestration of charcoal and recalcitrant, hydrophobic organic matter and to the effects of naturally invading, post-®re, N-®xing vegetation. Both fertilization and N-®xing vegetation caused marked overall increases in soil C and N. # 2001 Elsevier Science B.V. All rights reserved.