Distribution and spatial correlation of tree species along an altitudinal gradient in the Selva Lacandona, Chiapas

Abstract

In this paper the distribution and spatial correlation patterns of tree species along an altitudinal gradient in the Metzabok Protected Natural Area (PNA) in the Selva Lacandona, Chiapas State was analyzed. A 20 × 50 m sampling unit (SU) was installed in each altitudinal strata (AS), and divided into 10 sampling subunits (SSU) of 10 x 10 m targeting pole-sized trees. Within each SSU, one 5 × 5 m plot was installed to register the saplings, and within this, another two 2 × 2 m plots were established for the sampling of seedlings. The spatial distribution of pole-sized trees, saplings and seedlings was analyzed with the Morisita-Horn index; whereas the distribution and spatial correlation of pole-sized trees by height categories (lower, middle and higher) and AS was evaluated using Ripley’s univariate K(t) and bivariate K₁₂(t) functions. The mean spatial pattern of the pole-sized class for the three height categories along the altitudinal gradient was clumped (), as were the patterns of the saplings and the seedlings. Ripley´s K₁₂(t) function indicates that AS 2, 3 and 5 of the lower-middle height classes showed both spatial repulsion and attraction, while lower-higher and middle-higher had a behavior of independence and of spatial repulsion, respectively. These findings provide the basis for the implementation of forestry strategies focused on the conservation of the tree species distributed in the Metzabok PNA.