Spatial Distribution Patterns and Correlation of Trees in Karst Evergreen Deciduous Broad-leaved Mixed Forest

Trees were divided into different forest layers according to tree height based on the survey data of each tree in a 1.28hm² fixed plot in a karst evergreen deciduous broad-leaved mixed forest in Maolan. Then the spatial distribution pattern of trees based on individual and marker points was analyzed by using g(r) and k_mm(r). The results showed that on 40 m scale, trees in understory, substory and main story showed aggregation distribution at 0–18, 0–26 m and 0–2 m scales, respectively, while trees at other scales showed random or uniform distribution. The DBH of understory trees showed a significant negative spatial correlation at small scale. There was a significant negative spatial correlation between DBH, canopy width and biomass markers in substory at mesoscale, while there was no significant correlation between markers in the main story at the whole research scale. There was a significant positive spatial correlation between individuals of understory and substory at 2 m scale, and a significant positive spatial correlation between the individuals in substory and main story at 0–3 m scale. In general, affected by microtopography and diffusion restrictions, trees in different forest layers in karst evergreen deciduous broad-leaved mixed forest show aggregation at small scale, and intra-competition mainly occurs in the understory and the substory. The correlation between individuals in different forest layers were mainly between the substory and main story, and between the substory and undestory.