大老岭自然保护区日本落叶松林凋落物分解及养分释放研究

Litter Decomposition and Nutrient Release of Larix kaempferi Forest in Dalaoling Nature Reserve

[目的]研究外来引进树种日本落叶松林凋落物对土壤养分的影响。[方法]采用分解袋法分别对18年生和24年生日本落叶松林以及周围针阔混交林凋落物的分解和养分释放规律进行了研究。[结果]凋落物分解和养分释放速率均表现为针阔混交林>日本落叶松纯林;24年生日本落叶松林>18年生日本落叶松林。其中不同林分的凋落物残留率与时间呈指数相关,凋落物年分解系数(K)也表现为针阔混交林(0.555 6)>24年生日本落叶松林(0.445 0)>18年生日本落叶松林(0.366 2)。凋落物分解速率与初始N元素含量呈极显著正相关,而与C/N比呈显著负相关,高的木质素含量对凋落物的分解有一定影响。C元素、K元素表现为直接释放模式,而研究中C/N比和C/P比相对较高,使N元素和P元素均表现为先富集后释放的模式。各养分元素的残留率总体呈现出18年生日本落叶松林>24年生日本落叶松林>针阔混交林的格局。[结论]不同林分凋落物分解和养分释放速率差异较大。凋落物年分解系数表现为针阔混交林>24年生日本落叶松林>18年生日本落叶松林。

Objective]To illustrate the effects of exotic species Larix kaempferi forest on soil nutrition.[Method] The litter decomposition and nutrient release of L.kaempferi forest in Dalaoling Nature Reserve were investigated u-sing litter bag.[Result]It was showed that the litter decomposition and nutrient release rates followed the order of：coniferous and broad leaved mixed forest 〉24-year-old L.kaempferi forest 〉18-year-old L.kaempferi forest.The litter retention rate had an exponential relationship with time （R2 〉0.94,P〈0.001）.The coefficients （K）of lit-ter decomposition were 0.555 6,0.445 0 and 0.366 2 for the three forest types,respectively.The litter decomposi-tion rate showed a significantly positive correlation with the initial N content （P〈0.01）,but significantly negative-ly correlated with the C/N ratio （P〈0.05 ）.Besides,high content of initial lignin inhibited the litter decomposi-tion.C and K showed the direct release mode,while N and P followed a mode of concentration at first and then re-lease.The retention rate of all elements showed that 18-year-old L.kaempferi forest 〉24-year-old L.kaempferi for-est 〉the coniferous and broad leaved mixed forest.[Conclusion]Litter decomposition and nutrient release rates were different in different forest stands,with the coefficient of litter decomposition showed as the coniferous and broad leaved mixed forest〉24-year-old L.kaempferi forest〉1 8-year-old L.kaempferi forest.