青海大通退耕还林地生物量与生产力的研究

对青海大通县退耕还林地生物量和林地生产力进行了研究.结果表明,在浅山区,群落总生物量和总生产力与枯枝落叶层现存量呈显著正相关,以模式D(中国沙棘)的总生物量和总生产力最大,为29.5 t/hm2和9.36 t/(hm2·a),排序为模式D(中国沙棘)＞模式C(青杨 枸杞)＞模式E(柠条)＞模式B(紫花苜蓿)＞模式A(川赤芍).在脑山区,总生物量和总生产力主要取决于乔木层的生物量,以模式F最大,排序为模式F(青海云杉)＞模式G(华北落叶松)＞模式J(青杨 中国沙棘)＞模式K(青海云杉 中国沙棘)＞模式H(白桦 青海云杉);同时,乔木层的生产力与灌木层和草本层的生产力之和呈显著负相关,乔木层对其下的灌木和草本植物有明显的抑制作用.

Research on biomass and productivity of conversion cropland to forest in Datong County of Qinghai Province

The biomass and productivity of conversion cropland to forest in Datong County of Qinghai Province were analyzed in the paper.The result indicated that in the shallow-mountainous area,the total biomass and the total productivity of the community assumed connected remarkably with the existent mass of litter layer of forestland.The total biomass and the total capacity of model D(Hippophae rhamnoides ssp.sinensis) were the biggest,which were 29.5 t/hm~2 and 9.36 t/(hm~2.a),and the range was pattern D(Hippophae rhamnoides ssp.sinensis) > pattern C(Populus cathayana Lycium barbarum) > pattern E(Caragana korshinskii) > pattern B(Medicago sativa) > pattern A(Paeonia veitchii).In the high-mountainous area,the total biomass and the total capacity were decided mainly by the biomass of tree layer,pattern F was the biggest,and arranges as pattern F(Picea crassifolia) > pattern G(Larix.principis rupprechii) > pattern J(Populus cathayana Hippophae rhamnoides ssp.sinensis) > pattern K(Picea crassifolia Hippophae rhamnoides ssp.sinensis) > pattern H(Betula latyphylla Picea crassifolia).At the same time,the level productivity assumed a remarkable inverse correlation with the sum of productivity of the bush level and the field layer.This explained that in high-mountainous area the tree layer has the obvious inhibitory action to the bush and herb under it,because canopy density of forest was increased along with the years of conversion cropland to forest.