Structure and regeneration dynamics of three subtropical midmontane moist evergreen broad-leaved forests in southwestern China, with special reference to bamboo in the forest understories

Abstract

Two midmontane moist evergreen broad-leaved forests on the Ailao Mountains, Yunnan, and one on Mount Emei, Sichuan, southwestern China were studied to characterize the forest structure and dynamics as manifested in size, age, canopy gaps, regeneration modes, and the survival of seedlings. The most dominant canopy trees were species of Lithocarpus and Castanopsis of Fagaceae along with species of Machilus of Lauraceae and of Schima of Theaceae. The vertical structures of the forests were multilayered. All the canopy species had multimodal-shaped size and age distributions. In each forest of the study sites, the mean size of a canopy gap, caused mainly by the death of canopy trees, was smaller than 65 m2. No surviving seedlings of Fagaceae species were found in understories having bamboo with a coverage greater than 25% in any quadrat of the three forests. The poor seedling bank in the study forests is apparently due to the presence of bamboo in the understory. The tree regeneration may be synchronously related to the bamboo flowering event (interval approximately 55–60 years).