Abstract:

In a fixed plot of 100 m×100 m in a close-to-nature Phyllostachys edulis stand, which was divided into 100 units by adjacent grid inventory in Tianmu Mountain National Nature Reserve, Zhejiang Province, a whole station was used to measure coordinates of each bamboo tree. Spatial structure unit was established with Voronoi diagram spatial analysis function of GIS. Four spatial structure indices, including aggregation index, age mingling, competition index and the nearest bamboo number, were selected and principal component analysis was conducted to analyze the relationship between spatial structure and biomass of the P. edulis stand. The results showed that the ranking of spatial structure indices in their importance was: aggregation index>age mingling>the nearest bamboo number>competition index.Aggregation index was significantly negatively correlated with bamboo biomass per unit area, and high aggregation was a basic precondition for improving bamboo biomass per unit area. Increase in age mingling played a role in promoting bamboo biomass per unit area, and age mingling of great bamboo biomass was more than 0.5. Bamboo biomass per unit area decreased with increasing its nearest culm number. When the nearest culm number of target bamboo was four, the target bamboo most likely obtained high production. Bamboo biomass per unit area of target bamboo slightly declined with competition index.

Key words: close-to-nature Phyllostachys edulis stand, spatial structure, biomass, principal component analysis, Voronoi diagram