HR: 0800h
AN: B41A-0164    [Abstracts]
TI: The legacy of forest harvest and burning on ecosystem carbon storage in the northern midwest, USA
AU: * Gough, C M
EM: gough.21@osu.edu
AF: Ohio State University Department of Evolution, Ecology, and Organismal Biology, 318 W. 12th Ave., Columbus, OH 43210 United States
AU: Vogel, C S
EM: csvogel@umich.edu
AF: University of Michigan Biological Station, 9008 Biological Rd., Pellston, MI 49769 United States
AU: Harrold, K H
EM: kharrold@middlebury.edu
AF: Middlebury College, Middlebury College, Middlebury, VT 05753 United States
AU: George, K D
EM: Kristen.George@ColoState.EDU
AF: Colorado State University, Department of Atmospheric Science, Fort Collins, CO 80526 United States
AU: Curtis, P S
EM: curtis.7@osu.edu
AF: Ohio State University Department of Evolution, Ecology, and Organismal Biology, 318 W. 12th Ave., Columbus, OH 43210 United States
AB: Over 90 % of the forested area in the upper Great Lakes region was harvested by the early 20^th century. In many cases, harvests were followed by uncontrolled burns, similar to current patterns of disturbance in many developing countries. While afforestation in the northern midwest has resulted in increased regional carbon (C) storage, the rate of C storage by forests will depend on the severity of prior disturbance and consequent changes in site quality. We were interested in how long the legacy of poor management practices from the early 20^th century would be reflected in forest C storage rates. We investigated C cycling and storage following disturbance in mixed deciduous forests of northern lower Michigan, USA. Study plots ranged in age from 6 to 68 yrs and were created following experimental clear-cut harvesting and fire disturbance. Annual C storage was estimated biometrically from measurements of wood, leaf, fine root, and woody debris mass, mass losses to herbivory, soil carbon content, and soil respiration. Maximum annual carbon storage, or net ecosystem production (NEP), in the disturbed stands was 50 % lower than that of adjacent, undisturbed forest. This decrease was caused by a reduction in site quality following disturbance. However, during regrowth the cut and burned forest rapidly became a net C sink, storing 0.86 Mg C ha^-1 yr^-1 after six yrs. Carbon storage reached a peak of 1.00 Mg C ha^-1 yr^-1 after 50 yrs and declined to 0.57 Mg C ha^-1 yr^-1 after 68 yrs. Above- and below-ground net primary production (NPP) averaged 42 and 59 % of total NPP, respectively, with fine root litter production accounting for 57 % of total NPP. Soil heterotrophic respiration was high, ranging from 4.55 Mg C ha^-1 yr^-1 in the 6-yr-old stand to 5.74 Mg C ha^-1 yr^-1 in the 50-yr-old stand. Soil C and coarse woody debris pools exhibited a U-shaped trend over time following disturbance. Mineral soil and coarse woody debris pools lost C at a combined annual rate of 1.10 Mg C ha^-1 yr^-1 in the 6-yr-old stand, but these pools accrued C at a rate of 0.30 Mg C ha-^-1 yr^-1 in the 68-yr-old stand. Detritus inputs augmented soil C six years after harvest and this legacy C persisted in the oldest, 68-yr-old stand. This resulted in higher soil C than in an adjacent undisturbed mature forest. These results demonstrate that lasting decreases in site quality following disturbance result in long-term reductions in forest C storage.
DE: 1851 Plant ecology (0476)
DE: 4806 Carbon cycling (0428)
DE: 4815 Ecosystems, structure, dynamics, and modeling (0439)
DE: 4845 Nutrients and nutrient cycling (0470, 1050)
DE: 4850 Marine organic chemistry (0470, 1050)
SC: Biogeosciences [B]
MN: Fall Meeting 2005