鼎湖山马尾松林凋落物分解对凋落物输入变化的响应

为了了解我国南方森林常见的人为干扰（凋落物收取）活动对生态系统养分循环的影响,研究了鼎湖山马尾松林3种主要树种凋落物分解及其养分释放对凋落物输入量变化的响应。这3种树种分别为马尾松（Pinus massoniana）、荷木（Schimasuperba）和锥栗（Castanopsis chinensis）。凋落物输入量变化分别为凋落物去除（L-）、加倍（L＋）和对照（L）3种处理,每种处理25个重复。经过18个月的处理试验,凋落物分解速率及其养分释放随树种、分解阶段和凋落物处理不同而异。荷木、马尾松和锥栗分解物平均残留率分别为0.46±0.01、0.42±0.01、0.40±0.02,其中,荷木与锥栗、马尾松差异性显著。不同处理间的凋落物分解速率差异显著,加倍、对照和去除处理样地凋落物的平均残留率分别为0.51±0.08、0.53±0.09和0.55±0.08。凋落物加倍处理促进了凋落物分解过程中C的释放,而去除凋落物处理则抑制了N、P的释放。以上结果表明,凋落物收取活动不仅直接带走凋落物中的大量养分,而且抑制了凋落物分解及其养分释放。

Response of litter decomposition to changes of litter input in a pine forest of Dinghushan

Responses of litter decomposition and its nutrient release to changes of litter input were studied in a pine forest of Dinghushan to investigate the effect of human impact（litter harvesting） on nutrient cycling in the plantations of southern China.Three types of litter（Schima superba,Castanopsis chinensis and Pinus massoniana） were selected and three treatments of litter input were employed to evaluate decomposition.The treatments were litter addition（L＋）,control（L） and litter removal（L-）,with 25 replicates per each treatment.Results showed that after 18 months of treatments,litter decomposition rate and its nutrient release differed with litter type,decomposition stages and treatments.The average remaining rates were 0.46 ± 0.01,0.42 ± 0.01,0.40 ± 0.02,respectively for Schima superba,Pinus massoniana and Castanopsis chinensis.The average remaining rate of Schima superba was significantly higher compared to those of Pinus massoniana and Castanopsis chinensis.The difference of litter decomposition rates between treatments was statistically significant.The average remaining rates in the L-,L,L＋ plots were 0.51 ± 0.08,0.53 ± 0.09 and 0.55 ± 0.08,respectively.Litter addition significantly increased C release from decomposing litter,while litter remove inhibited significantly the release of N and P from decomposing litter.Our results suggest that litter harvesting not only directly removes nutrients from harvested litter mass but also inhibits litter decomposition rate and nutrient release from decomposing litter.