Abstract:

Objective: By examining the relationship between the stand productivity and community structure , and analyze the factors affecting stand productivity in different forest layers of a broad-leaved Korean pine (Pinus koraiensis) mixed forest community in Changbai Mountain, the purpose of this study is to build a scientific foundation for the restoration and sustainable management of temperate forests. Method: Using vegetation survey data from a 40 hm² fixed monitoring sample plots of broad-leaved Korean pine forest in Changbai Mountain Nature Reserve in 2014 and 2019, we selected woody plants with diameter at breast height (DBH) ≥ 5 cm from the sample plot as the object. The stand was divided into four layers, namely the dominant layer, the subdominant layer, the medium layer and the pressed layer, using the interval of 10 cm breast diameter. We used the Pearson correlation to analyze the relationship among species diversity, stand density, structure diversity , and productivity factors; a structural equation model using productivity as the response variable was developed to investigate the effects of species diversity, structural diversity and stand density on productivity. Result: 1) There was a significantly positive correlation between stand density and productivity (P<0.05), and it declined as the rise of forest layers. 2) The analysis of the Pearson correlation shows that the species of Shannon-Wiener index is significantly positive (P<0.05), and the correlation of the correlation of the forest rising has weakened. Conversely, there is a significant negative (P<0.05) correlation between the Sorensen index that represents β diversity, but this correlation is not significant in the medium wood layer and the Asian advantage wood layer. In addition, the species Pielou index and productivity are significantly negative (P<0.05). And the correlation coefficients increase with the rise of the forest and decrease; DBH Gini index and DBH Pielou are significantly negative with productivity, and this correlation weakens with the upper forest layer, and has no significant correlation with the productivity in the superior wood layer. The DBH Shannon-Wiener index is significantly positively (P<0.05) correlated with productivity, and the correlation between the upper forest movement is reduced, and the correlation coefficient is reduced from 0.44 to 0.31. 3) In different forest layers, he stand density had a significant impact on productivity (P<0.001), and its action intensity gradually decreased with the rise of forest layers, and the path coefficient dropped from 0.59 to 0.27. Species diversity had a significant positive (P<0.05) effect on productivity in the pressed and medium layers, but had no effect on productivity in the dominant and subdominant layers; structural diversity indirectly affected stand productivity in the pressed and medium wood layers by acting on species diversity and stand density, and directly affected stand productivity in the dominant and subdominant wood layers. Conclusion: To summarize, the study shows that stand density had a significant effect on productivity in each forest layer (P<0.05), and the intensity of action gradually decreased as the forest layer increased. The direction and intensity of the influence of species diversity and community structure on productivity differ across forest layers. Therefore, in the practice of forest production and management of forest resources, the relationship between forest structural characteristics at different vertical spatial scales of forest layers and forest productivity should be fully considered.

Key words: broad-leaved Korean pine forest, different forest layers, productivity, community structure, species diversity