Control of depth to permafrost and soil temperature by the forest floor in black spruce/feathermoss communities.

Abstract

Changes in depth to permafrost and soil temperature were investigated for 4 years after treatment of the forest floor on small plots by fire and mechanical removal of half the forest floor layer and the entire layer. The only treatments to show a consistent, statistically significant effect were the mechanical removals. Fire treatments usually did not have a statistically significant effect on depth to permafrost and soil temperature in summer; fire consumed only small amounts of the forest floor because of wet conditions at the time of burning. Treated plots showed an almost constant drop in permafrost depth at the end of each summer with no evidence that this rate was decreasing. Thicknesses of mean active layers at the end of the fourth summer after treatment were as follows: control, 26.2 cm; lightly burned, 31.8 cm; heavily burned, 49.6 cm; half the forest floor removed, 85.0 cm; and entire forest floor layer removed, 137.5 cm. Changes in vegetation on the plots are also reported.

Citation

Dyrness, C.T. 1982. Control of depth to permafrost and soil temperature by the forest floor in black spruce/feathermoss communities. Res. Note PNW-RN-396. Portland, OR: U.S. Department of Agriculture, Forest Service, Pacific Northwest Forest and Range Experiment Station. 19 p