木林子大样地两个木姜子属物种空间分布格局及关联性

该文以湖北木林子国家级自然保护区15 hm2大样地同属物种木姜子(Litsea pungens)和黄丹木姜子(L. elongata)]为研究对象,通过成对相关函数和不同零模型(完全空间随机模型、异质泊松模型和先决条件模型)的方法分析两个物种的空间分布格局、种内和种间空间关联性,从同属物种的空间分布格局角度探讨群落的构建机制。结果表明:(1)种群空间分布格局研究中,两个种的空间分布格局大致为聚集分布。基于CSR零模型,木姜子和不同径级(幼树、小树、中树和成年树)的聚集尺度分别为0~114 m、0~103 m、0~56 m、0~34 m和0~16 m,黄丹木姜子和不同径级的聚集尺度分别为0~150 m、0~150 m、0~59 m、0~56m和0~14 m;基于HP零模型,木姜子整体的空间分布格局聚集尺度为0~23 m,其中幼树、小树和中树均在0~22 m呈现聚集分布,成年树仅在0~3 m尺度上表现为聚集分布,黄丹木姜子整体的空间分布格局聚集尺度为0~36 m、140~150 m,各径级的聚集尺度分别为0~35 m、0~35 m、0~12 m和0~6 m。(2)种内关联性研究中,木姜子和黄丹木姜子不同径级个体种内关联在小尺度上基本呈现正关联,随着尺度的增大变为微弱的无关联或负关联。(3)种间关联研究中,木姜子对黄丹木姜子和黄丹木姜子对木姜子的空间关系大致相同。总体上,两物种之间均体现为在30 m尺度内对另外一个物种呈现正关联,40~68 m尺度内呈现负关联;不同径级之间都表现为无关联,偶尔出现正关联或负关联。研究认为,种群空间分布格局基本上为聚集分布,其主要受到生境异质性和扩散限制的影响,木林子大样地中木姜子和黄丹木姜子空间分布格局存在相似性,而不同的生境偏好可能是导致两同属物种共存的原因。

Spatial distribution patterns and correlations of two species of Litsea in large sample plot in Mulinzi National Nature Reserve

In this paper, species of the same congeneric species(Litsea pungens and L. elongata )in large sample plot of 15 hm² in Mulinzi National Nature Reserve of Hubei Province were taken as the study object. The spatial distribution pattern, intraspecies and interspecific spatial correlations of the two species were analyzed by pairwise correlation function and different zero models(complete spatial randomness, heterogeneous Poisson and antecedent condition), and the construction mechanism of the community was discussed from the point of view of the spatial distribution pattern of the same congeneric species. The results were as follows:(1)In the study of population spatial distribution pattern, the spatial distribution pattern of the two species was generally aggregation distribution. The aggregation scales on the basis of the CSR zero model, the L. pungens and the different diameter stages(sapling, small tree, medium tree, adult tree)were 0-114 m, 0-103 m, 0-56 m, 0-34 m, and 0-16 m, respectively, and the aggregation scales of the L. elongata and the different diameter stages were 0-150 m, 0-150 m and 0-59 m, 0-56 m and 0-14 m; On the basis of the HP-zero model, the spatial distribution pattern of the whole L. pungens was 0-23 m, where in all of the sapling, small and medium trees were 0-22 m, and the aggregation distribution of adult trees was only on the scale of 0-3 m. The aggregation scale of the whole spatial distribution pattern of L. elongata was 0-36 m and 140-150 m, and the aggregation scale of each diameter grade was 0-35 m, 0-35 m, 0-12 m and 0-6 m.(2)In the study of intraspecific correlation, the intraspecies correlation of different diameter individuals showed positive correlation on a small scale, and became weakly unrelated or negative with the increase of scale.(3)In the study of interspecific correlation, the spatial relationship between the two species was about the same. On the whole, the two species showed positive correlation with another species within 30 m scale and negative correlation within 40-68 m scale, and there was no correlation between different diameter grades, and there was positive or negative correlation between the two species. It is considered that the spatial distribution pattern of the population is basically aggregation distribution, which is mainly affected by habitat heterogeneity and diffusion. The spatial distribution patterns of L. pungens and L. elongata in large sample plot are similar, and different habitat preferences may be the cause of the coexistence of the two species.