Short-term effects of harvesting on carbon storage of boreal Larix gmelinii-Carex schmidtii forested wetlands in Daxing'anling, northeast China

摘要

Forested wetlands are recognized as long-term terrestrial C sinks, so they are very important in global C accounting. Daxing'anling is the main area of Chinese forested wetlands, however, effects of harvesting on ecosystem C storage for boreal forested wetlands are still poorly understood. The aim of this study was to evaluate the short-term effects of selective harvest on ecosystem C storage and C sequestration for Larix gmelinii-Carex schmidtii forested wetlands in Daxing'anling, northeast China, by measuring and comparing changes in its total ecosystem C storage (biomass, litter, and soil C pools) and annual C sequestration under four harvest treatments (0.0% - uncut, 25% - low, 35% - moderate and 50% - high of total volume) after 5 years, so as to provide references for managing wetland resources. We found that: (1) the vegetation C storage of harvested plots decreased significantly by 15.5-38.6% of that 99.61 t C ha(-1) in the uncut stand and showed a decreasing trend with increasing harvest intensity; (2) low intensity harvest increased the soil C storage by 19.4%, however, both moderate- and high-intensity harvest caused significant reductions (30.1-48.5%) relative to 174.93 t C ha(-1) in the uncut stand; (3) low intensity harvest led to a mild increase in the total ecosystem C storage while moderate- and high-intensity harvest resulted in significant reductions (33.2-41.6%) compared with the uncut stand (274.54 t C ha(-1)); (4) significantly greater total NPP (69.1-83.2%) and annual C sequestration (52.0-78.7%) were in the low- and moderate-intensity harvest stands compared to the high intensity harvest and uncut stands (8.28 t ha(-1) yr(-1), 5.08 t C ha(-1) yr(-1) and 6.48 t ha(-1) yr(-1), 3.52 t C ha(-1) yr(-1)). Finally, it appears that low intensity harvest may not only be capable of sustaining the ecosystem C sink for this forested wetland type, but restore its C sequestration capacity more efficiently