Abstract: By the method of substituting spatial difference for time change,this paper studied the species diversity of 4 successional communities in the evergreen broad-leaved forest of Gutian Mountain Nature Reserve,Zhejiang Province. Sixteen typical plots were investigated and each plant in the contiguous grid quadrates was measured,with Shannon-Wiener index (H),Pielou index (J_SW,J_SI) and Simpson index (D) determined.The results showed that the Shannon-Wiener index of coniferous forest,coniferousbroad leaf mixed forest,Schima superba forest and Castanopsis eyrei forest tree layers was 1.9670,2.4975,2.6140 and 2.4356,respectively,with a tendency from small to big and then to small in the course of succession.Among all successional communities,the species diversity of the shrub layer in coniferous-broad mixed forest was the biggest,with the Shannon-Wiener index 2.8625,while that of the herb layer in coniferous forest was the biggest,with the Shannon-Wiener index 1.5334.As for vertical structure,the species diversity of coniferous forest,coniferous-broad mixed forest and Castanopsis eyreiforest was all in the order of shrub layer > tree layer > herb layer,while that of Schima superba forest was in the order of tree layer > shrub layer > herb layer.During succession,herb layer had the biggest variation in species diversity,with the variation coefficient of H,J_SW,J_SI and D being 0.1572, 0.0806,0.0899 and 0.1884,respectively,while shrub layer had the smallest one,with the variation coefficient of H,J_SW,J_SI and D only being 0.0482, 0.0385, 0.0142 and 0.1553,respectively.

Key words: Okhotsk Sea, Walleye pollock, Distribution, Environment of fishing ground