秦岭火地塘林区四种主要树种凋落叶分解速率

Decomposition rate of four dominant tree species leaf litters in Qingling Huoditang forests

利用野外分解袋法对秦岭火地塘林区油松、华山松、华北落叶松、锐齿栎凋落叶的分解速率和养分释放趋势进行研究。结果表明,分解2年后,4种树种凋落叶的干物质残留率在35.6%～58.6%,残留率大小顺序为油松>华山松>华北落叶松>锐齿栎。除油松与华山松凋落叶之间残留率差异不显著外,各树种之间凋落叶分解后的残留率差异显著。在2个试验年度中,4-9月凋落叶分解最快,在其他月份保持较平稳的分解速度,分解前12个月凋落叶失重速度明显大于后12个月,呈明显的季节和阶段性差异。利用Olson模型对凋落叶分解50%和95%所需时间进行估测,结果显示,不同树种所需时间差异显著,其中锐齿栎凋落叶95%被分解所需时间最短,为5.43年,油松最长,为9.87年。凋落叶中N、P元素在分解第1年均表现出富集现象,直至1年后达到一个最高值后,开始释放,C含量则呈现出逐步下降的趋势。导致不同树种凋落叶分解速率及养分释放速率差异主要与不同凋落叶的初始质量和性质有关。

By using field litter bag technique,this paper studied the decomposition rate and nutrient release of the leaf litters from Pinus tabulaeformis,P.armandii,Larix principis-rupprechtii,and Quercus aliena var.acuteserrata in Qingling Huoditang forest area.After two years decomposition,the remaining percentage of the leaf litters was 35.6%-58.6%,and ranked as P.tabulaeformis P.armandii L.principis-rupprechtii Q.aliena var.acuteserrata.Except that P.tabulaeformis and P.armandii had no significant difference in their leaf litters remaining percentage,there existed significant differences in the remaining percentage among the test tree species.During the two-year experiment,the leaf litters decomposed fastest during the period from April to September,and kept a stable decomposition rate in other months.Compared the second year,the mass loss rate of the leaf litters in the first year was higher,and showed obvious seasonal and stage-wise difference.The estimation of the required time to decompose 50% and 95% of the leaf litters by the Olson model showed that there was a prominent discrepancy among the tree species.The required time to decompose 95% of leaf litter was the shortest（5.43 years）for Q.aliena var.acuteserrata,and the longest（9.87 years）for P.tabulaeformis.The elements N and P in leaf litters appeared enrichment in first year of decomposition,and started to release after the enrichment peak reached;while the C presented a decreasing trend.The differences in decomposition rate and nutrient release rate among the tree species were mainly related to the initial quality and the nature of the leaf litters.