Patrón Espacial de Especies Arbóreas de Importancia Ecológica y Su Relación Con La Altitud, La Pendiente y La Precipitación en Bosques Húmedos Tropicales Del Pacífico Colombiano

Abstract

Identifying the factors and mechanisms that promote and maintain the high diversity and patterns of spatial distribution of plant species in tropical forests, has been the subject of debate and discussion. Thus, the present study evaluates the effect of topography (altitude, slope) and precipitation in the spatial pattern of tree species of ecological importance. For this purpose, the data generated from the census of tree species (DBH> 10 cm) were used in eleven permanent plots of one hectare established by USAID-CONIF in 2014 in the towns of Chontadural- Mutatá (Antioquia), Pizarro, Río Pepé, Canton San Pablo (Chocó), Bahía Málaga, Bajo Calima, Cajambre River (Buenaventura), Acapa and Bajo Mira - Frontera (Nariño). The species with the highest value of ecological importance (IVI), most abundant and with presence in at least two plots, were selected. In order to identify the spatial distribution pattern (random, aggregate, dispersed) of the selected species, the functions L (d) of K-Ripley, G (r) of distance distribution to the nearest neighbor, g Pair correlation and coefficient of variation (CV). The binomial logistic regression was used to quantify the effect of altitude, slope, precipitation and average annual precipitation days on the distribution patterns identified in each species. Of the 602 species registered in the censuses, seven were selected (Brosimum utile, Camnosperma panamense, Pourouma bicolor, Pentaclethra macroloba, Symphonia globulifera, Welfia regia and Oenocarpus bataua) for presenting higher values of ecological importance between 1.09 and 2.30 and being represented in at least of the parcels. For these species the random and aggregate pattern was identified without any predominance of these. In the correlation of the abundances of the species and the ecological factors evaluated, the average annual precipitation and the number of days of average annual precipitation were not related; While the altitude and slope had significant negative relationships with the abundance of six of the seven species selected (C. panamense, O. bataua, P. macroloba, P. bicolor, S. globulifera and W. regia). Finally, binomial logistic regression models showed that the aggregate distribution patterns of the analyzed species had a higher relationship with altitude and slope mainly, with positive or negative risk probabilities of this aggregate pattern being presented according to the species. These results are important since they indicate that the structure of the populations (abundance and distribution patterns) of the species with greater ecological weight identified in the tropical humid forests of the Colombian Pacific, depends on the topographic variables, altitude and slope. Thus, in the conservation measures of these species (especially those with some category of threat), the inclusion of the greatest possible environmental heterogeneity within the protected areas must be taken into account.