Characteristics of gap in subalpine coniferous forest in western Sichuan

Abstract

Abstract: In order to explore the characteristics of gap disturbance in subalpine primary coniferous forests in western Sichuan Province,the gaps in the primary coniferous forest at Dawodang in Wanglang Nature Reserve were surveyed and analyzed according to the quantity,size,type and factors of gap formation,the type,number,species composition of gap maker (GM).The results showed that most gap makers died due to their aging and the descending capabilities of counteracting disadvantageous surroundings.The most popular manner of gap formation in the forest was breakage at the base of gap makers (51.23% of the total).The second was breakage on trunk (20.37%).Almost half of the gaps were formed by one tree(46.99% of the total), with an average of 1.95 trees per gap.The size of most expanded gaps was in the range of 100～300 m²,the gaps of 100～200 m² occupied the highest percentage in number (26.51% of the total),while those of 300～400 m² occupied the highest percentage in size (22.64% of the total).The size of most canopy gaps was under 200 m²,the gaps of 50～100 m² occupied the highest percentage in number and size (32.53% and 17.72% of the total).The average areas of canopy gap and expanded gap were 71.68 m² and 154.14 m²,respectively.

Key words: Pine wood nematode disease, Pathogenic bacteria, Complex infection, Propagation

CLC Number:

S718

XIAN Junren, HU Tingxing, WANG Kaiyun, ZHANG Yuanbin. Characteristics of gap in subalpine coniferous forest in western Sichuan[J]. cje, 2004, (3): 6-10.

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