Abstract: This paper studied the development, distribution, vegetation and environment of the gaps of secondary forests on Zijing Mountain. The gaps are mainly produced by logging of Pinus massoniana, and they distribute randomly. 53 woody species are found in the gaps, Liquidambar formosana having the highest frequency (100%),and Kalopanax pictus, Quercus fabri, Pistacia chinensis and Quercus variabilis being very frequent species. 1283 individuals are recorded, of which, 18.75% is Liquidambar formosana., and Dalbergia hupeana, Quercus fabri, Kalopanax pictus and Quercus variabilis are 10.9, 8.7,5.5 and 5.3%, respectively. 7 woody species and 190 individuals per 100 m² are found in the gaps. According to variance analysis, the density distributions of major species such as Liquidambar formosana, Dalbergia hupeana, Quercus fabri and Quercus variabilis are significantly different from Poison, showing that their distributions are nonrandom. In the gaps, individuals under 2 cm of basal circumferennce account for 59.0% of the total. The higher the basal circumference, the less the number of individuals. The number of individuals is decreased by 70.5% from 2 cm to 4 cm of basal circumference, and by 96.2% from 2 cm to 10 cm of it. The temporal distributions of light intensity, air humidity and air temperature in the gaps are similar to those on open lands, but their spatial patterns are more complicated.

Key words: Gap, Secondary forest, Biodiversity, Zijin Mountain, flue-cured tobacco, suitability., climate change