Carbon Distribution in Subalpine Forests and Meadows of the Olympic Mountains, Washington

Abstract

Estimates of C storage in mountainous regions are rare. Forest–meadow ecotones in subalpine ecosystems, which contain a mosaic of forests and meadows, may be particularly sensitive to future changes in climate and are therefore important to include in estimates of terrestrial C storage. In this study, we quantified soil C and ecosystem C pools in subalpine forest and meadow soils of the northeastern (NE, dry climate) and southwestern (SW, wet climate) Olympic Mountains. Carbon concentrations of mineral soil are relatively high in upper horizons, ranging from 43 to 142 g kg−1 in NE soils and 27 to 162 g kg−1 in SW soils. Northeastern meadow soils store more C than NE forests , while SW forest soils store more C than SW meadows Ecosystem C storage is greater in forests than in meadows. Under a warmer climatic scenario with drier summers and wetter winters, subalpine C storage may decrease in the NE and increase in the SW, and changes in C storage will be closely related to vegetation distribution, ecosystem productivity, decomposition rates, and local disturbance regimes. Because ecosystem processes and associated C storage differ between high‐ and low‐elevation ecosystems, it is important that data from both high‐ and low‐elevation sites are included in estimates of C storage in terrestrial ecosystems.