湘西北长果安息香种群数量与分布格局

The population quantity and distribution pattern of the endangered plant Changiostyrax raxdolichocarpa

对湖南石门壶瓶山景关门、桑植龙潭坪茅垭村样地的长果安息香(Changiostyrax raxdolichocarpa)种群数量和分布格局进行调查和分析。结果表明:长果安息香种群的年龄结构呈衰退型,个体数量主要集中在小树(IV龄段),幼龄级株数和老龄级株数匮乏;长果安息香种群在进入生理死亡年龄前有2个死亡高峰,第1个峰值产生于幼树(II、III龄段),主要原因是种内和种间竞争(主要是光照),第2个峰值产生于中树长成大树阶段(V、VI龄段),除种内、种间对环境的竞争外,生长地土层浅薄、大树倒伏及人为砍伐亦加剧了该峰值的产生;种群整体呈聚集分布类型,小树向中树、大树变化过程表现出聚集分布向随机分布转变,导致长果安息香濒危的主要原因是种子萌发率极低、种群竞争能力较差以及人为干扰等。

The population quantity and distribution pattern of Changiostyrax raxdolichocarpa in Hupingshan and Sangzhi, Hunan province, were investigated and analyzed. Age structure analysis showed the population of Changiostyrax raxdolichocarpa was a declining one, in which there were mainly small trees （IV age group） with infant and old trees lacked. Before entering the physiological age of death, there were 2 mortality peaks of Changiostyrax raxdolichocarpa, one of the which was in the young trees stage （Ⅱ, Ⅲ age groups） caused by intraspecific and interspecific competition （mainly for light） and the other was in the stage of the trees growing into big ones （Ⅴ, Ⅵ age groups）. Besides, shallow soil, lodging of big trees and man-made cutting intensified the peaks. The whole population presented a gathering distribution, in which sapling trees distributed in a gathering way and big ones in a random way. Through investigation we found that the reasons causing Changiostyrax raxdolichocarpa endangered were low seed germination rate, less competitiveness and Man-made interference etc.