The Characters And Regeneration Of Picea Crassifolia Forest Gap In Qilian Mountain

Forest gap disturbance,an important small scale disturbance,0ften occurs in forest community. It is one of the most important drives for maintaining of forest ecosystem ,and has an important influence on forest structure , cycle and regeneration .Studies on forest gap have been one of the most active fields of forest ecology in foreign countries and our countries nowadays, after Watt defied the concept of forest gap. There has been no report about forest gap studies of Picea crassifolia forest in Qilian Mountain. The paper, in order to show characters of distribution and formation of Picea crassifolia forest gap, rules of temporal-spatial distribution of the gap microclimate, characters of regeneration and biomass distribution in the gap ,the characters of gap and regeneration of Picea crassifolia forest gap are analyzed .All these will provide the scientific basis for studying the succession of Picea crassifolia forest.The main results are as follows:(1)In this paper, gap characteristics of Picea crassifolia forest are analyzed. The results shows that the size of most expanded gaps is in the range of 32.6～274.2 m2,the gaps of 50～75 m2 occupies the highest percentage in number(27. 8% of the total),while those of 75～100 m2 occupies the highest percentage in size(21% of the total). The size of most canopy gaps is in the range of 10.8～234.9m2,the gaps of 50～75 m2 occupies the highest percentage in number and size(35.4% of the total and 26.2% of the total) .The most important manner of gap formation is artificial cutting, and the secondly important manner is the breakage on stem. Gaps formed by 1～2 gap makers is of 80%,and by 4 gap makers is seldom(7.7% of the total). The gap maker of 8～12 m high occupies the highest percentage in number (60.6% of the total)(2)Microclimate factors of Picea crassifolia forest gap are analyzed, it indicates : because of sun radiation,geography character and the tree, spatial distribution of air temperature and relative humidity show the phenomena about dynamic displacement; There is significant difference between microclimate factors of different area in the...