Tree isolation enhances seed dispersal behavior by scatter-hoarding rodents

Abstract

Human activities cause changes in the structure of landscapes that may impact negatively on wildlife at different levels. Agriculture and livestock, for example, have frequently led to landscapes of forest fragments and isolated trees within grass/crops matrices. These changes influence the distribution and behavior of animals, and the key ecological processes that depend on them. In this study, we analyzed how tree isolation influences the patterns of acorn dispersal by scatter-hoarding rodents in Holm oak Quercus ilex fragmented woodlands of Central Spain. Our results show that an increase in the degree of tree isolation promotes the concentration of rodents under oak canopies looking for cover and food during the seeding season. This concentration increases dramatically the levels of competition among rodents for space and acorns beneath oak canopies, which resulted in an increase in acorn caching to reduce seed pilferage by conspecifics, thus favoring acorn dispersal from the mother tree. These shifts in rodent spatial distribution and behavior would favor tree recruitment through increased rates of seed dispersal, which may counterbalance to some extent the potential negative effects of forest fragmentation given the overall loss of seed-producing trees.