PROCEEDINGS: Index of Abstracts

CARBON STORAGE IN MANAGED FORESTS OF THE NORTHERN GREAT LAKE STATES

Jeanette L. Rollinger-1 and Terry F. Strong-2

1-Research Ecologist, USDA Forest Service, North Central Forest Experiment Station, 1831 Highway 169 E., Grand Rapids, MN 55744. 2-Research Forester, USDA Forest Service, North Central Forest Experiment Station, 5985 Highway K, Rhinelander, WI 54501.

Carbon (C) storage in forest ecosystems is a significant part of the total terrestrial C pool, and may potentially be manipulated as an important C sink. The influence of management on C pools must be understood before guidelines can be suggested for maximizing C sequestration in forests. Studies of hardwood, red pine (Pinus resinosa Ait.), aspen and hybrid poplar stands located primarily in Minnesota, Wisconsin and Michigan have been and are currently being conducted to address the effects of common management practices on C storage. Factors studied include: (1) the effect of harvest intensities on soil and biomass C, (2) the effect of forest conversion from second growth hardwoods to red pine, and from old fields to hybrid poplar plantations or red pine, on ecosystem C, (3) the effects of soil compaction and biomass removal on stand productivity. Total aboveground C ranged from 303 to 335 Mg/ha, and did not differ by harvest intensity 40 years after partial cutting northern hardwoods on a ten-year cycle. However, distribution of C among aboveground components was significantly different (proportionately more C was in the understory with increased intensity of harvest). In both hardwood and some red pine stands, increasing harvest intensity appears to reduce C storage in soil. Soil compaction and forest floor removal reduced aspen shoot biomass and quantity of C in the forest floor. Total ecosystem C continued to decrease for five years after aspen harvest. However, the ecosystem began to gain C after seven years and accumulation continued until C reached a maximum at 70 years post-harvest. Total soil C was generally unchanged after aspen clear-cutting. Adjacent red pine plantations and hardwood stands on the same soils averaged the same mass of C in vegetation, in soil across the entire profile, and in total ecosystem C (211 and 206 Mg/ha, respectively), although the hardwood averaged 14 years older than red pine. Soil C accumulation in twelve to eighteen year old hybrid poplar plantations exceeded that on adjacent agricultural fields.