刺栲和短刺栲叶被采食量的测定

A Measurement on the Grazed Leaf Biomass of Castanopsis hystrix and Castanopsis echidocarpa

在刺栲和短刺栲9458个叶片中,有60％的叶片被虫食.叶片虫食痕迹多样,很难复绘出叶原来的形状测定虫食面积.提出用重量比值法求算叶被采食率（I_g）的公式.比较非虫食叶和虫食叶的大小发现,动物并不选择采食大的或小的叶片,确定该方法是切实可行的.测定出刺栲和短利栲叶的被采食率分别为9.98％和 13.06％,被采食量分别为0.0656 t/hm^2·a和0.2857 t/hm^2·a.还发现动物主要采食幼嫩叶片.

Sixty percent of 9458 leaves of Castanopsis hystrix and C. echidnocarpa are grazed. The grazed forms are varied and hardly copied into the original shape of leaves to measure the grazed leaf area. A formula by ratio of leaf weight is suggested to calculate the grazed ratio: in which, W1 and W2 is the weihgt of ungrazed leaves and grazed leaves respectively N is the number of total sampling leaves and n1 is the number of ungrazed leaves in N It is found that the insects do not select grazing large of small leaves by the comparative study on the size between ungrazed and grazed leaves, demonstrating that this method is reliable and feasible. Measured with this method, the grazed ratio of C. hystrixleaves and C. echidnocarpa leaves is 9.98% and 13.06% respictively; the grazed leaf biomass of C. hystrix is 0.06566 t/hm2· a and that of C. echidnocarpa is 0.2875 t/hm2· a. Near 2.51% of the net primary productivity of C. hystrix and C. echidnocarpa in the stands is grazed by insects annually. It is also found that the insects graze chiefly young leaves.