Pattern of spatial distribution of the tree species of the El Salto region of Durango

Abstract

The purpose of this study was to determine the pattern of spatial distribution of trees present in the region of El Salto, Pueblo Nuevo, Durango. For this purpose, 12 communities that are representative of the conditions of the forests of the region were selected, where 269 round sites of 0.1 ha were randomly distributed at an altitude range of 1 500 to 3 000 m. The pattern of distribution of the trees by altitude level was determined by applying Cox’s and Morisita’s indices, and the pattern corresponding to each species was tested with the Poisson and negative binomial distribution adjustment tests. The level of aggregation was evaluated through the clustering parameter K, the ratio of the average density per taxon in relation to the mean 1/K, and the average number per individual per species in relation to the individuals present in the sampling unit m*. Cox’s and Morisita’s indices ranged from 12.05 to 17.39 and from 1.18 to 1.28, respectively, indicating that at each level of altitude individuals are distributed on an aggregate basis. At the same time, Cox’s index and the negative binomial distribution adjustment (P>0.05) pointed out that the individuals per species are distributed in clusters. The values of the parameter K, 1/K and m*, which ranged from 0.002 to 0.454, from 2 to 500 and from 9 to 69, respectively, exhibit a high degree of aggregation between individuals.