林下套种阔叶树的马尾松林凋落物生态学研究 Ⅱ.凋落物养分归还动态

Forest Litter Ecology in Masson′s Pine Stand and Its Mixed Forests Formed by Inter-planting with Hardwood Tree Species Ⅱ.Dynamics of Nutrient Return From Litterfall

在马尾松林下分别套种拉氏栲、青栲、闽粤栲、格氏栲和苦槠,形成针阔混交异龄林.对上述5个混交林群落以及马尾松纯林的凋落物进行每月定期收集、取样和化学分析.结果表明,凋落物各组分的养分含量存在较大差异,N、P、K、Ca、Mg的含量范围分别为0.325%～1.298%、0.024%～0.097%、0.037%～0.655%、1.277%～3.540%、0.235%～0.610%.枯叶中N、P、K的含量表现出一定的季节格局,但Ca和Mg的动态规律不明显.不同的群落类型,凋落物中各养分元素的年归还总量大小均为:Ca>N>Mg>K>P,其大小范围依次为99.3～188.18kg·hm-2、20.62～67.46kg·hm-2、16.24～40.59kg·hm-2、3.9～13.08kg·hm-2、1.95～4.07kg·hm-2.上述5个混交林群落凋落物中的养分年归还总量分别为238.05kg·hm-2、213.77kg·hm-2、223.93kg·hm-2、289.90kg·hm-2、304.12kg·hm-2,而马尾松纯林为142.01kg·hm-2.所研究的5个混交林群落,其养分归还量表现出比较明显的双峰型季节动态.各养分元素之间稍有不同,但总的来说,第1峰值出现在2～4月份,第2峰值则出现在8～9月份.

Five unevenaged coniferhardwood forest communities were developed after Castanopsis lamontii,Cyclobalanopsis myrsinaefolia,Castanopsis fissa,Castanopsis kawakamii,and Castanopsis sclerophylla,were separately interplanted under the canopy of mature Masson′s pine plantationsMonthly collection of litterfall was conducted in the above five mixedspecies communities and also in pure Masson′s pine standChemical analysis of the litter samples indicated that nutrient concentrations of various litter components were different,with N ranging from 0325% to 1298%, P 0037% to 0655%,K 0024% to 0097%,Ca 1277% to 3540%,and Mg 0235% to 0610%Seasonal patterns were significant for the concentrations of nitrogen,phosphorus and potassium,but not for calcium and magnesiumTotal nutrient return of the five elements for the six stands consistently decreased in the order:Ca>N>Mg>K>P,amounting to 993~18818 kg·hm-2,2062~6746 kg·hm-2,1624~4059 kg·hm-2,39~1308 kg·hm-2,and 195~407 kg·hm-2,respectivelyAnnual nutrient return amounts from forest litterfall were,respectively,23805,21377,22393,28990,30412 kg·hm-2,for the above five mixed communities,and 14201 kg·hm-2 for pure Pinus masssoniana standSeasonal dynamics of nutrient return in the mixed stands showed binomial patterns,generally with the first peak occurring between February and April,and the second peak in August or September