Aims Many researches have shown that the interlaced roots of dwarf bamboo (Fargesia nitida) can influence the regeneration of trees and the growth of seedlings and saplings through competition for light, water and nutrients. We explore the effect of dwarf bamboo on the regeneration of Abies faxoniana on the forest edge and estimate the effect of dwarf bamboo on the dispersal and community development. We asked: 1) how will quantitative characteristics and population structure change under different densities of F. nitida, and 2) how will the density of F. nitida influence the growth and biomass allocation of A. faxoniana seedlings?

Methods We sampled five belt transects and analyzed 30 plots within each transect in Wolong Giant Panda Nature Reserve (30°51'41″ N,102°58'21″ E) during August and September 2005. The transects were selected based on different densities of F. nitida (i.e., distance to the F. nitida cluster): 2 m outside the cluster (Zone 1), 1 m outside the cluster (Zone 2), 1 m inside the cluster (Zone 3), 2 m inside the cluster (Zone 4) and 3 m inside the cluster (Zone 5). We measured the height, basal diameter and crown of each A. faxoniana seedling. We used five BD classes: Ⅰ (0< BD<0.3 cm), Ⅱ (0.3 cm≤BD<0.6 cm), Ⅲ (0.6 cm≤BD<0.9 cm), Ⅳ (0.9 cm≤BD<1.2 cm), Ⅴ (BD≥1.2 cm), and five size classes: Ⅰ (0<H<15 cm), Ⅱ (15 cm≤H<30 cm), Ⅲ (30 cm≤H<45 cm), Ⅳ (45 cm≤H<60 cm), and Ⅴ (H≥60 cm). The seedlings were divided into two groups, large (H>0.2 m) and small (H≤0.2 m), to explore the accumulation and allocation of biomass byA. faxoniana seedlings. We obtained data on biomass from regression equations based on a sample of 60 A. faxoniana seedlings.

Important findings Regeneration and growth of A. faxoniana seedlings were restrained in the F. nitida-dominated zones, and dispersal of the A. faxoniana population and development of an A. faxoniana-dominated community were affected. Closer to F. nitida clusters, the number of old seedlings and the efficiency of transformation (seedling number ratio of the next BD class to the preceding BD class) were reduced (the older the A. faxoniana seedlings, the smaller the efficiency of transformation); the peak of number of seedlings moved from larger (Ⅲ) to the smallest size (Ⅰ); the total biomass and allocation of biomass aboveground ofA. faxoniana seedlings decreased; and the presence of F. nitida restrained the height growth of small (Ⅰ)A. faxoniana seedlings (confirmed by regression of basal diameter and height). The expansion of crowns of bigger (Ⅲ) seedlings increased in moderate density (Zone 4) ofF. nitida.