高山森林不同类型粗木质残体腐殖化特征

摘要

Humification of coarse woody debris was one of the main pathways of soil formation and carbon sequestration in alpine forest ecosystems, where type of coarse woody debris and decay class could play an important role in coarse woody debris humification thanks to its insulation effect. However, the results were still not clear which limit the understanding and response of coarse woody debris humification. Therefore, three 100 m×100 m plots were sampled in a Minjiang fir (Abies faxoniana) primary forest ecosystem around 3600 m altitude in western Sichuan in August, 2013. In order to explore effects of type of coarse woody debris and different decay class, we investigated different decay class fallen logs, snags, stumps and large branches, each decay class of coarse woody debris and collected altogether 60 trees. Results clearly showed that: snag, fallen log and large branch of humus carbon, humic acid and fulvic acid carbon content increased with the change of decay levels, whereas snag humus carbon, humic acid and fulvic acid carbon content was maintaining decline. At the same time, snag, stump, large branch, fallen log, which humification degree respectively 52.93%~85.88%, 49.2%~73.68%, 54.94%~67.21% and 53.41%~68.68%. Snag, its humification degree was significantly higher than the other three types of coarse woody debris, and humification degree was the highest in the late humification (IV decay class or V decay class). For further understanding about the alpine forest ecosystem of plant and soil interaction process which is of great significance.%高山森林粗木质残体腐殖化是促进生态系统土壤发育和碳吸存的主要途径之一，并可能受到腐烂等级和木质残体类型的影响，但一直缺乏必要的关注。因此，在2013年8月，以青藏高原东缘海拔3600 m左右的高山森林中具有代表性的岷江冷杉（Abies faxoniana）原始林为研究对象，根据区域内坡度和物种组成设置3个100 m×100 m的典型样地，在研究样地内随机选取5个腐烂等级的岷江冷杉粗木质残体，每个腐烂等级3株，4种粗木质残体，共计60株，调查和研究区域内不同腐烂等级倒木、枯立木、根桩和大枯枝等主要类型粗木质残体的腐殖化特征。结果表明：枯立木、大枯枝和倒木腐殖质碳、胡敏酸碳和富里酸碳含量随腐烂等级增加而增大，而根桩腐殖质碳、胡敏酸碳和富里酸碳含量随腐烂等级增加而减小，并且枯立木在各个分解阶段腐殖质碳、胡敏酸碳和富里酸碳含量均保持较高水平。同时，枯立木、大枯枝和倒木的腐殖化度随腐烂等级增加呈增大趋势，根桩腐殖化度却随着腐烂等级增加而减小，其腐殖化度分别为52.93%~85.88%、49.2%~73.68%、54.94%~67.21%和53.41%~68.68%。枯立木腐殖化度明显高于其他3种类型粗木质残体，且在腐殖化后期（腐烂Ⅳ级或Ⅴ级）腐殖化度最大。这对进一步认识高山森林生态系统植物-土壤互作过程具有重要意义。