Effects of Forest Gaps on Litter Lignin and Cellulose Dynamics Vary Seasonally in an Alpine Forest
Effects of Forest Gaps on Litter Lignin and Cellulose Dynamics Vary Seasonally in an Alpine Forest
复制标题
高山森林中森林间隙对凋落物木质素和纤维素动态的影响随季节变化
作者：
Li, Han;Wu, Fuzhong;Hu, Yi
为了解林窗及其冠层是如何通过重新分配冬季积雪覆盖和生长季的水热条件来控制凋落物木质素和纤维素的动态变化的，对岷江冷杉（Abies faxoniana E.H.）Wilson）森林，位于长江上游和青藏高原东部的过渡地带。在凋落物分解的第一年，凋落物表现出绝对纤维素损失和绝对木质素积累，除了红桦凋落物。凋落物纤维素和木质素的变化受林窗位置、林窗时期和树种的交互作用影响显著。凋落物纤维素表现出更大的损失，在冬季与最高的日损失率在积雪期观察。冬季差距中心深积雪覆盖下纤维素和木质素含量变化较大，而生长季封闭冠层下纤维素和木质素含量变化较大。结果表明，冬季变暖导致积雪季节性减少，可能会限制高山森林生态系统中凋落物纤维素和木质素的降解，这可能会进一步抑制凋落物分解。因此，持续的冬季变暖和林隙消失将减缓寒冷生物群落中落叶层的土壤碳固存。
To understand how forest gaps and the associated canopy control litter lignin and cellulose dynamics by redistributing the winter snow coverage and hydrothermal conditions in the growing season, a field litterbag trial was conducted in the alpine Minjiang fir (Abies faxoniana Rehder and E.H. Wilson) forest in a transitional area located in the upper reaches of the Yangtze River and the eastern Tibetan Plateau. Over the first year of litter decomposition, the litter exhibited absolute cellulose loss and absolute lignin accumulation except for the red birch litter. The changes in litter cellulose and lignin were significantly affected by the interactions among gap position, period and species. Litter cellulose exhibited a greater loss in the winter with the highest daily loss rate observed during the snow cover period. Both cellulose and lignin exhibited greater changes under the deep snow cover at the gap center in the winter, but the opposite pattern occurred under the closed canopy in the growing season. The results suggest that decreased snowpack seasonality due to winter warming may limit litter cellulose and lignin degradation in alpine forest ecosystems, which could further inhibit litter decomposition. As a result, the ongoing winter warming and gap vanishing would slow soil carbon sequestration from foliar litter in cold biomes.