关帝山华北落叶松林凋落物分解过程及其养分动态

采用野外凋落物收集器法和埋置凋落物分解袋法,对关帝山林区华北落叶松林凋落物的数量和组成、年凋落过程、不同埋置层凋落叶分解速率和营养元素动态进行了分析.结果表明:华北落叶松林年凋落物总量为19.15 t · hm-2 · a-1,其中树叶占35.7%,树枝占54.4%,花果占6.7%,树皮和杂物占3.1%.凋落物逐月动态变化为单峰型,10月为年凋落量高峰期,但各成分的凋落进程不同.华北落叶松林凋落物残留量均值为9.803t/hm2,凋落物分解常数为1.95;凋落叶在不同埋置层的分解失重率有明显差异,凋落叶的周年平均失重率29.82%,分解半衰期1.5～2a,分解95%需7～9a;凋落叶分解过程中,氮磷钾元素含量表现出不同的动态过程,其中氮素的年动态变化总体上属于富集过程,到后期开始出现下降,磷素的年动态变化表现为7月份前下降,之后出现快速富集,到生长季末期富集过程变缓,钾素的年动态变化表现为持续下降过程,不出现富集过程.

Decomposition process and nutrient dynamic of litterfall in a Larix principis\| rupprechtii stand in Guandishan Mountains

We investigated the quantity and composition, annual decomposition process decomposition rate and nutrient dynamics at different depths of the litterfall in a Larix principis\|rupprechtii stand in Guandishan Mountains, using field collection container, burying of the decomposition bags at different depth and laboratory analysis. The results showed that the total amount of litterfall was 19.15 t?hm-2?a-1, of which 35.7% was for leaves, 54.4% for twigs, 6.7% for flowers and fruits, and 3.1% for barks and other materials. Furthermore, the month by month annual dynamics of the forest litter appeared to be single climax curve, in which the highest point occurred in October, while the different components had different decomposition rate. The residual litter in the Larix principis\|rupprechtii stand was 9.803 t?hm-2 with a decomposition constant of 1.95. The decomposition rate at different depths varied significantly. The annual weight loss of new defoliated leaves was 29.82%. The decomposition half life was 1.5-2a, while it took 7-9a to reach a decomposition proposion of 95%. During the decomposition process, the dynamics of nitrogen, phosphorus and potassium showed different patterns. The enrichment of nitrogen gradually increased in most of the year, but decreased at the sencond hall of the year. The enrichment of phosphorus decreased before July, but increased rapidly after that and slowed at the end of the growing season. The potassium content decreased all the year being washed off in the decomposition process without any enrichment.