Spatial patterns and associations of vegetation is an expression of ecological processes, it might provide insights into forest dynamics and change with succession driven by resource competition and changes of environmental conditions. The spatial patterns and associations of Haloxylon ammodendron sand-fixing plantation in three development stages (initial, optimal and decay) was analyzed in an oasis-desert ecotone in the Hexi Corridor, Northwest China, providing a framework for improving our general understanding of pattern variation in artificial forests, and preliminary discussed the factors which may be responsible for shaping the spatial patterns and associations. Five 0.3-ha (50m×60m) permanent plots were established in three development stages, H. ammodendron was classified into seedlings, juvenile trees and mature trees, all individuals were measured and stem-mapped. Modified Ripley’s K-function (L-function) was used for the univariate spatial pattern analysis, bivariate L12-function was used for the analysis of spatial associations.
Results/Conclusions
Results showed that the overall spatial pattern of H. ammodendron plantation shifted from initially clustered via random to cluster at last, in the optimal stage, it is less cluster compared with the initial and decay stages with a reduction in tree density; in initial stage and optimal stage, the competition between conspecifics may be the dominant factors which influence plants’ growth and survival then may affect the spatial patterns of population, while in decay stages, the interactions between conspecifics may be the dominant factors under tree size-asymmetric competition, the abiotic stress may be the dominant factors under tree size-symmetric competition; the fierce competition for soil water resource in initial stage lead to intense density-dependent mortality, and the plantation showed cluster pattern in decay stages at all scales for the abiotic heterogeneity. We believe that the results will provide effective information for developing management programs and implementing close-to-nature artificial forests which follow the regulation on natural vegetation succession.