秦岭林区锐齿栎次生林种群空间分布格局

Spatial pattern of secondary Quercus aliena var. acuteserrata forests in the Qinling Mountains

以秦岭林区阳坡、阴坡2个典型地段上的锐齿栎次生林为研究对象,运用点格局分析方法 O-ring函数分析了不同坡向、不同发育阶段种群空间分布格局及不同坡向锐齿栎种群的种内与种间空间关联性,探讨锐齿栎空间格局形成和种群维持机制。结果表明:阴坡锐齿栎种群聚集程度高于阳坡;两种坡向种群各发育阶段空间分布格局相似,从幼树到大树均呈现出聚集到随机甚至均匀分布的规律;不同坡向种群各发育阶段间关联性不同,阳坡各发育阶段间呈一定的正相关,而阴坡呈一定的负相关;阳坡中,山杨与锐齿栎种群分布呈一定正相关,灯台树、鹅耳枥与其呈一定负相关,在阴坡,山杨、漆树与锐齿栎呈一定正相关,灯台树、青榨槭、鹅耳枥与其呈一定负相关。结果表明:目前,阳坡锐齿栎种群结构较好,种内、种间竞争不激烈,而阴坡种群不仅受种间竞争的影响,同样受到种内竞争的制约,最终导致其林分结构较差,更新不良,从长远上看,适当疏伐可以增加林内透光性,有益于促进种群的更新与稳定。

Study of the spatial patterns of populations can these patterns. The population of secondary provide many important clues about underlying processes forming growth Quercus aliena var. acuteserrata is a representative forest type in the Qinling Mountains. This study was intended to investigate the spatial patterns of secondary Quercus aliena var. acuteserrata forests and to provide a basis for managing natural forests. Two sample plots were established, on a sunny slope and a shady slope, to analyze and compare spatial patterns of Quercus aliena var. acuteserrata population. The pair correlation function and univariate statistics of point patterns were used to analyze the spatial distribution of different development stages and habitats, while bivariate statistics was used to analyze spatial associations of different stages and of different populations on each plot. The change in population spatial pattern and association among different development stages and different populations was compared to explore inherent mechanisms forming the spatial patterns. The results show that spatial distribution patterns and the age structure of the Quercus aliena var. acuteserrata population were different for sunny and shady slopes. The degree of spatial distribution aggregated on the shady slope was higher than that on the sunny slope. The age structure appeared a reverse ＇ J＇ type on the sunny slope （ growing type）, while the population renewal was poor on the shady slope （declining type）. Initially, different developmental stages showed similar distribution patterns on both slopes, but these became random when young trees matured. Some differences appeared in the relevance of each development stageon each slope. Positive association was observed among developmental stages on the sunny slope, while negative association was observed among developmental stages on the shady slope. For example, on the sunny slope, the distribution patterns of Quercus aliena var. acuteserrata population were positively associated with Populus davidiana, but negatively associated with Bothrocaryum controversum and Carpinus turczaninowii. On the shady slope, the distribution patterns of Quercus aliena var. acuteserrata population were positively associated with Populus davidiana and Toxicodendron vernicifluum, but negatively associated with Bothrocaryum controversum, Acer davidii and Carpinusturc zaninowii. In summary, the distribution patterns of Quercus aliena var. acuteserrata population were basically reasonable on the sunny slope; intraspecific and interspecific competition were not fierce. The distribution patterns within the Quercus aliena var. acuteserrata population were not only influenced by interspecific competition, but were also restricted by intraspecific competition on the shady slope, suggesting that proper thinning could increase light transmittance, thereby improving the regeneration and stability of such Quercus aliena var. acuteserrata population.