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FOREST ECOSYSTEM CARBON AND NITROGEN ACCUMULATION DURING THE FIRST CENTURY AFTER AGRICULTURAL ABANDONMENT
Citation:
Hooker, T. D. AND J E. Compton. FOREST ECOSYSTEM CARBON AND NITROGEN ACCUMULATION DURING THE FIRST CENTURY AFTER AGRICULTURAL ABANDONMENT. ECOLOGICAL APPLICATIONS. Ecological Society of America, Ithaca, NY, 13(2):299-313, (2003).
Description:
Forests of the northeastern U.S. are expected to serve as a substantial sink for carbon (C) and nitrogen (N) as they recover from extensive clearing and agriculture. However, questions remain concerning the rate, distribution and duration of this potential sink. We used a chronosequence approach to examine the changes in ecosystem C and N pools during the first 115 years of forest development after agricultural abandonment in Rhode Island, USA. All sites had similar soils, climate, land-use history, and dominant overstory vegetation (Pinus strobus), but varied in time since agricultural abandonment. Total ecosystem C increased linearly across the chronosequence at an average rate of 2.10 Mg C ha-1 yr-1. Most of the C was sequestered into plant biomass (73%) with less in the forest floor (17%) and deep mineral soil (6%; 20-70 cm depth). Total ecosystem N did not change over time; instead, N accumulated in the forest floor (11.6 kg N ha-1 yr-1) and plant biomass (4.1 kg N ha-1 yr-1), and these increases were roughly balanced by decreasing N content in the mineral soil (-12.4 kg N ha-1 yr-1). Over 90% of the storage of C and N in plant biomass occurred in the bole wood (C:N 350). Since nearly two-thirds of the forests in Rhode Island have established since 1900, ecosystem C storage will likely continue as the importance of coarse woody debris and coarse roots increases over the next century, if these forests are left intact. Our work suggests that high C:N ratio wood biomass of regrowing temperate forests is an important sink for both C and N for at least a century after agricultural abandonment.