Nearest neighbour relationships in Pinus yunnanensis var. Tenuifolia forests along the Nanpan River, China

Abstract

Forest stand structural diversity can be examined at different scales. Smallscale structural changes are the basis of forest structural diversity and habitat heterogeneity, and play a key role in biodiversity conservation. Most research on forest structure has focused mainly at stand level and above, with little attention paid to fine-scale structure and correlations among different forest stand attributes. We set up four permanent plots within a secondary forest community of Pinus yunnanensis var. tenuifolia mixed forests along the Nanpan River in southern China. We analyzed their nearest-neighbor relationships using a bivariate distribution of stand spatial structural parameters (SSSP) with the aim of understanding the processes that drive structural diversity in the development of a secondary forest community. Our results revealed that communities with different disturbance histories and species compositions differed in the level of species mixture. Large, small, and medium-sized trees were well mixed within the community, both conspecific and heterospecific individual with varying densities. All plots exhibited a uniform size differentiation pattern. Trees with different dominance levels or mixture levels were randomly distributed within the plots, and only few of these displayed clumped or regular distribution. Pearson’s correlation analysis revealed that distribution patterns may be related to species composition and diameter differentiation, though their relationship was very weak. The results of this study are relevant to optimize forest management activities in the studied stands, and promote tree growth, regeneration and habitat diversity at the fine scale.