Forest ecosystem carbon and nitrogen accumulation during the first century after agricultural abandonment
2003
Hooker, Toby D. | Compton, Jana E.
Forests of the northeastern United States 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 determine changes in ecosystem C and N 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 differed in time since agricultural abandonment. Total ecosystem C increased linearly across the chronosequence at a mean rate of 2.10 Mg C·ha–¹·yr–¹. Most of the C was sequestered into plant biomass (73%) with less stored 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 a significant decrease in N content of 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, net ecosystem C storage will likely continue for the next century if these forests remain undisturbed. Our results show that wood biomass is an important sink for both C and N in regrowing forests for at least one century after agricultural abandonment. Corresponding Editor: A. D. McGuire.
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