Regeneration Patterns in Old-Growth Abies-Betula Forests in the Wolong Natural Reserve, Sichuan, China

(1) Regeneration patterns of Abiesfaxoniana, Betula utilis and B. albosinensis in central Sichuan, China were interpreted by stand structural analysis (age, size, horizontal patterning) of tree populations in old-growth ( > 250 years) stands. (2) Seedlings, saplings and young trees were scarce in stands where bamboo (Sinarundinaria fangiana) impeded tree regeneration. Shrub density and woody plant species richness were lower in stands with high bamboo cover. (3) Regeneration patterns indicate that A. faxoniana and B. utilis relative densities were similar where bamboo was dense and that A. faxoniana was more than twice as abundant as B. utilis where bamboo cover was low or absent. Bamboos seem to impede A.faxoniana regeneration more than that of B. utilis. Both species regenerated in canopy gaps, but A. faxoniana less so than B. utilis where bamboos were dense. This produces higher Betula density in bamboo stands. Sizes of young patches of B. utilis tended to be larger than patches of A.faxoniana. Partitioning of gaps by size may contribute to coexistence of A. faxoniana and B. utilis in old-growth stands.