Document: RIC-3-59-53

Soil C supply restricts soil N cycling in a 17 year old whole tree harvest

COBB, R.C* ^1,2 and J.WMCLAUGHLIN ^2,3

Harvard University, Petersham, MA 03166, USA ¹
Cooperative Forestry Research Unit, Univ of Maine, Orono, ME 04468, USA ²
Texas Clean Rivers, Houston, TX, USA ³

Abstract:
Silvicultural perturbations of soil processes can have profound influences on ecosystem productivity. While immediate and short-term (< 5 years) impacts of a variety of harvest techniques have been well studied, long term (15+ years) quantification of these disturbances on soil processes are much less common. In 1979, the Weymouth Point Paired Watershed Study located in north central Maine, USA was initiated to examine the impacts of whole tree harvesting on soil and ecosystem processes. 17 years after silvicultural perturbation, the harvested watershed had 2.3 times greater CO₂ flux relative to the unharvested adjacent control stand. In contrast, net N mineralization was 4.2 times lower in the harvested watershed relative to the control. Net N mineralization was associated with labile soluble organic N (R²=0.49) and soil organic matter (R²=0.35), both of which were lower in the harvested watershed relative to the control. 17-year results reveal that the harvest continues to exert a profound impact on soil processes that will likely continue until soil C and N pools have recovered to preharvest conditions.

Keywords: whole tree harvest, soil organic matter, net N mineralization

This abstract is being presented at: 3:30 PM in session:
Poster Session #15: Nutrient Cycling.