Abstract

ANTUNEZ, Pablo; QUINONES-PEREZ, Carmen Z.; SANTIAGO-GARCIA, Wenceslao  and  SUAREZ-MOTA, Mario E.. Density funcions: an application for delimiting optimal intervals of climate and physiography for forest species. Agrociencia [online]. 2018, vol.52, n.7, pp.1031-1042. ISSN 2521-9766.

The space a species occupies in a natural system can be delimited by the physical-geographic medium or by the environmental conditions that define it. The objective of this study was to delimit climate intervals in which the maximum presence rate occurs of three tree species native to the Sierra Norte of Oaxaca, Mexico (Pinus pseudostrobus Lindl (var. Apulcensis), Pinus patula Schl. et Cham, and Quercus macdougallii Martínez), in function of nine environmental variables using the Weibull density function and the finite Gaussian mixture model. To this end, we used data from 634 plots measuring 1,000 m2, which were established systematically in the study area. The results showed that high dispersion of the two pines species is related to mean precipitation from April to September. In contrast, the scarce presence of Quercus magdougalli, an endemic species, seems to be related to the reduced intervals of winter precipitation and to altitude. The two density functions tested allowed definition of optimal environmental intervals for each species. The finite mixture model was more flexible than the Weibull function when identifying bimodal distributions, particularly for the two pines species, whose observed dispersion pattern was more heterogeneous than that of Quercus. The results obtained will serve to prioritize areas for purposes of conservation or commercialization.

Keywords : Gaussian mixture model; Weibull function; Quercus magdougalli; Sierra Norte of Oaxaca; temperate forest.