A STUDY OF THE STRUCTURE AND COMPOSITION OF AN OLD GROWTH AND SECONDARY BROAD-LEAVED FOREST IN THE AILAO MOUNTAINS OF YUNNAN, CHINA

A cooperative U.S.A.-China ecological study took place at the Xujiaba Nature Sanctuary on the northern crest of the Ailao Shan (mountains) in central-west Yunnan. By making forest access difficult and keeping human immigration low, the mountainous topography of Yunnan has assisted in protecting forest cover. This project studied the vegetational and bird structure and composition of an old growth and a secondary evergreen broad-leaved forest. The study found that the old growth had better developed layers, canopy stems were wider and taller, and there was a greater diversity of bird species. The secondary forest had a higher stem density in the canopy, more even-aged stems in the canopy, more coppiced stems in the canopy, and a greater canopy and overall basal area. Both forest types maintained a high diversity of woody species, but different species were dominant in each forest type and in the canopy and subcanopy of the forests. Natural forests are rare in China and are dwindling quickly. Most natural forest is found in frontier regions and it is here where research and management efforts are needed most urgently. In the nature reserves more ecological research, conservation education, and greater efforts to understand local demands, use, and knowledge about the forests are needed.