关键词: 小麦-油菜间作, 水杨酸甲酯, 麦长管蚜, 自然天敌, 分布型

Abstract: The production,nutrient element content and decomposition rates of litterfall of two forests were studied in mid-altitude of Laoshan mountain,Tianlin county,Guangxi.The results indicate:1.The mean annual litterfall in evergreen-deciduous broad-leaved mixed forest and pure Chinese fir plantation are 5.153 and 5.176t.ha^-1 respectively,and total amount of eight nutrient elements for the former is 159.82kg(ha穣r )^-1,in which N 80.54,P 3.89,K 14.77,Ca 40.47,Mg 15.86 ,Mn 3.96,Cu 0.06 and Zn 0.27kg(ha.yr)^-1;for the latter they are 118.84,39.44,2.02.7.65,54.80.11.68,3.08,0.06 and 0. 11 kg(ha穣r )^-1,indicating the litterfalls belong to N-rich type and Ca-rich type respectively for the two forests.2.The rate of weight loss after 376 days on the forest floor is 44.50% for broad leaves,and 33.03% for needles.The exponential decay model is used and the annual decay rate of leaf litter is estimated to be 0.5978g(g穣r)^-1 for broadleaves,and 0.4025g(g穣r)^-1 for needles.showing that the decomposition of broadleaves is farster than that of needles.

Key words: wheat-oilseed rape intercropping, methyl salicylate, Sitobion avenae, natural enemy, distribution pattern.