RESPONSE OF BLACK SPRUCE (PICEA-MARIANA) ECOSYSTEMS TO SOIL-TEMPERATURE MODIFICATION IN INTERIOR ALASKA

Some 50 m2 of forest floor in a 140-yr-old black spruce ecosystem, which had developed on permafrost, was heated to 8-10°C above ambient temperature. This perturbation amounted to a 1589 degree-day seasonal heat sum (above 0°C), 1026 degree-days above the control total of 563 degree-days. Soil heating significantly increased decomposition of the forest floor, principally because of an increase in biomass loss of the 021 layer. The increased decomposition resulted in greater extractable N and P concentrations in the forest floor, higher N concentrations in the soil solution, and elevated spruce needle N, P, and K concentrations. -from Authors