南亞熱帶厚殼桂(Cryptocarya Chinensis)不同生活階段種群
摘要
Two aspects of life stages are important determinants in the spatial pattern of plant populations: one is spatial distribution of individual plants within life stages; the other is spatial association between different life stages. Using Ripley's univariate L(t) and bivariate L(subscript 12)(t) functions, we analyzed the spatial pattern within and between life stages of Cryptocarya chinensis in an 80 m × 80 m plot in lower subtropical China. Based on stem diameter and height, five life stages (Ⅰ, Ⅱ, Ⅲ, Ⅳ, Ⅴ) were distinguished. Ripley's univariate L(t) function showed clumped distributions within all life stages, with fine-scale random distributions in old life stages Ⅳ and V. From the bivariate L12(t) function, young life stages Ⅰ, Ⅱ and Ⅲ appeared significantly attractive to each other at local and intermediate distances, but independently distributed regarding old life stages Ⅳ, Ⅴ at almost all distances. The oldest life stage, Ⅴ, was independently distributed relative to other life stages. Considering these results, we inferred that the existence of suitable survival environments (e.g. canopy gaps) are a determinant in shaping the spatial pattern of young life stages of C. chinensis; with increasing body size with growth, intraspecific competition develops, and a fine-scale random distribution appears within old life stages.