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

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.

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

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