川西亚高山林线交错带植被凋落物量及养分归还动态

从2006—2008年,研究了川西亚高山林线交错带群落凋落物产量及N、P、K、Ca和Mg主要养分归还动态。结果表明:林线交错带植被凋落物年产量为389.83kg.hm-2.a-1,5种主要养分年归还量总量为15.82kg.hm-2.a-1,归还量排序为Ca>N>K>Mg>P。其中,叶、枝和其他混合杂物分别占凋落物总量的72.2%、17.9%和9.9%,占养分归还总量的87.4%、7.0%和5.6%。凋落物各组分及养分归还月动态均呈单峰曲线型变化,叶高峰期在9月,而枝、杂物则在10月。凋落物养分含量季节动态因不同凋落物组分和养分元素而异。叶凋落物中N、P、K和Mg含量在生长高峰的6、7月较高,而Ca含量较低;枝凋落物各元素含量总体上月变化不显著,其他混合杂物各元素含量6与10月相对较高,其余各月则无显著差异。

Litter production and nutrient return of vegetations in subalpine timberline ecotone of west Sichuan,China

In 2006-2008,investigations were made on the litter production and nutrient return of the vegetations in subalpine timberline ecotone of west Sichuan.The annual litter production of the vegetations was 389.83 kg·hm~(-2)·a~(-1),among which,leaf,branch,and miscellany occu pied 72.2%,17.9%,and 9.9%,respectively.The annual return of five main nutrients(N,P,K,Ca,and Mg)from the litters was 15.82 kg·hm~(-2)·a~(-1) in total,with the sequence of Ca＞N＞K＞Mg＞P,and 87.4%,7.0%,and 5.6% of the return came from leaf,branch,and miscellany,respectively.The monthly dynamics of different litter components and their nutrient return all showed one-peak,with the maximum in September for leaf and in October for branch and miscellany.The seasonal dynamics of the nutrient contents in litters differed with litter com ponents and nutrient kinds.In leaf litter,the contents of test five nutrients except Ca were higher in June and July；in branch litter,no notable monthly variation was observed for the test nutrients contents；and in the miscellany,the contents of test nutrients were higher in June and October than in other months.