Gap characteristics in the natural forests of Pinus yunnanensis alone the Jinshajiang Basin in Yunnan Province

Key words: 
• Pinus yunnanensis /
• natural forests gap /
• disturbance /
• Jinshajiang Basin /

Abstract: The gap characteristics and natural disturbance regimes of 45 gaps in the natural forests of Pinus yunnanensis were studied , in Baimahe Forest Farm and Xiangshuihe Forest Farm of Yongren County , in Yunnan Province .The results showed that these gaps were elliptic in horizontal form .The average area of expand gap (EG) and canopy gap (CG)were 469.42 m2 and 181.90 m2 respectively , the area percentage of both in the forest landscape were 28.23 % and 10.49 % respectively , and annual natural disturbance frequency of both were 0.672 1 % and 0.247 9 % respectively .So the return interval of the gap was gotten , about 400.48 a .These gaps mostly formed 40 a ago , and made by 1 to 3 gap makers (mainly by one).The diameter of gapmakers was mainly from 30 to 50 cm, and the height of which was mainly from 20 to 30 m .The manners of gap formation in the percentage order from high to low were :uprooting (33.7 %), breakage at trunk base (27.9 %), breakage on trunk (18.6 %), standing die (17.4 %), and breakage on branch (2.4 %).The combination of the different manners can be found often .Finally , based on the theory of gap dynamics , some suggestions on the natural forest of Pinus yunnanensis management were provided .[ Ch , 5 tab .10 ref .]