Spatial patterns of dominant species and their implication for natural secondary forest ecosystem dynamics in a reserved forest of north China

摘要

Spatial pattern analysis is useful to elucidate the type and importance of the ecological processes in forest ecosystem. To better understand the dynamics of the natural secondary forest ecosystem and to provide information regarding the interactions between arbors and shrubs, the spatial patterns of dominant species in a natural secondary forest was examined in this paper. We developed a 2 ha secondary forest plot by mapping the location of all woody plants (diameter at breast height = 1 cm). Univariate and bivariate Ripley's L(r) functions were utilized to evaluate the spatial patterns and association of the three dominant plants (P. davidiana, B. platyphylla and C. mandshurica). It was found that aggregated distribution was the main pattern in the dominant populations of the total and size-specific individuals of arbors at most scale. The degree of aggregation gradually decreased with size in B. platyphylla due to self-thinning while increased in P. davidiana which may attribute to the effects of logging for large-and medium-size woods in 1940s or 50s. In associations of intra-/interspecies pairs, positive association was the majority of intraspecies, whereas negative association was the domination in interspecies. Remarkable, mutual independence dominated in C. mandshurica vs. size-specific B. platyphylla pairs at most scales, and positive association emerged at greater than 8m scales in C. mandshurica vs. size-specific B. platyphylla-large, may contribute to different niche occupying that generated less competitions for resources, even the large ones could provide preferable shelter for shrubs.