New tools to study spatio-temporal interactions among species

Abstract

Ledo, V., Montes, F., Cañellas, I. 2013. New tools to study spatio-temporal interactions among species. Ecosistemas 22(3):52-57. Doi.: 10.7818/ECOS.2013.22-3.08

Second order moment functions are increasingly being used in the study of ecological processes. In this paper, we present two recently developed second order functions that allow us to study the spatio-temporal interactions between individuals belonging to two species or functional types. These functions were developed to study interactions among species in forest stands using the diametric distribution of the trees. The first of these functions is an intertype function, applied to a marked point pattern layer (K^rs_mm). It allows us to analyze the spatial correlation of a variable related to each individual and between species as a function of the distance. The second function is a replacement species function (r), by which it is possible to analyze the association between individuals belonging to two different species as a function of their diameter size differences or another variable associated with the individuals. In order to determine the behavior of both the K^rs_mm and the r functions in the analysis of forest systems in which different ecological processes are operating, three case studies are presented here: one in a mixed stand of Pinus pinea L. and Pinus pinaster Ait. in the northern plateau of the Iberian peninsula, another in a cloud forest situated in the tropical Andean region, and finally, one in the ecotone of  Pyrenaica Willd. and Pinus sylvestris L in the Central Mountain System of Spain. In these cases, both of the functions proposed are used to study the forest dynamics in experimental plots where all the trees are mapped. 
Key words: ecological processes; forest dynamics; mark correlation functions; point pattern analysis; Ripley’s K function; second order moment functions.