Gap characteristics and its effects on community regeneration of Quercus liaotungensis forest on Loess Plateau

A quantitative study was made on the Quercus liaotungensis forest gaps in Malan area of Loess Plateau.The results showed that small gaps(20-40 m2)and middle gaps(40-60 m2)were the dominant,and the age structure of the gaps was mostly at metaphase and anaphase.The main manners of gap formation were standing death and stem breakage,which accounted for 70.31% of the total gaps,and the numbers of forest gap-makers were mostly 1-3,suggesting that the forest gaps were mainly formed by natural disturbance.Among the gap border trees,Q.liaotungensis was the dominant.In the gaps,the abundance of Q.liaotungensis with different life history stages had different responses to the environmental factors.The abundance of seedlings was highly correlated with gap size and the height of gap border trees(R2=0.429,P0.01),that of saplings was highly correlated with the intensity of scattered light(R2=0.286,P0.01),and that of adult trees was not significantly correlated with environmental factors but significantly correlated with sapling abundance(R2=0.175,P0.05).