玉龙雪山自然保护区丽江云杉林林窗特征研究

研究了玉龙雪山自然保护区云杉坪典型丽江云杉林林窗干扰的基本特征．结果表明，滇西北亚高山丽江云杉林林窗占林分面积比例冠层林窗和扩展林窗分别为28．8％和42．5％，干扰频率以林窗密度计算，林窗出现的平均密度为35个·hm^-2左右．林窗大小分布为面积大于100m^2的大林窗约占25％，面积为50～100m^2的中等林窗占41％，面积小于50m。的小林窗占34％．形成林窗最重要的方式是干基和干中折断，其次是枯立滇西北亚高山丽江云杉林林窗形成木80％以上是丽江云杉，通常直径为40～50cm、高度为15～25m．每个林窗形成木数量多为1～2株，约占68．8％，5株以上很少，最多为6株．随着林窗面积由大变小，林窗中更新苗木的密度逐渐变大，小林窗中更新木密度约为大林窗的5倍．

Forest gap characteristic in a coniferous-Picea likiangensis forest in the Yulong Snow Mountain Natural Reserve, Yunnan Province, China

In this paper, some important parameters related to the gap disturbance regimes in a coniferous-Picea likiangensis forest in the Yulong Snow Mountain Natural Reserve, Yunnan Province were described. The results showed that expanded gaps occupied 42.5%, and canopy gaps occupied 28.8% of the land area in the forest. The frequency of gap disturbance was 35 gaps per hectares. There were 25% of small (gap area < 50 m2), 41% of middle (gap area 50-100 m2), and 34% of large (gap area > 100 m2) forest gaps. The most important manner of gap formation was the breakage at trunk base and its middle, and the secondly important manner was rotten. Gap maker in the forest was more than 80% of Picea likiangensis. The probability of making gaps was the greatest, when the big trees in the canopy layer got DBH 40-50 cm and height 15-25 m. Gaps formed by 1-2 gap makers was of 68.8%, and by 5 gap makers was seldom. The most of gap makers were 6 in a gap of the forest. The density of the seedlings in gap gradually increased with the forest gap from large to small.