Pioneer effects on exotic and native tree colonizers: insights for Araucaria forest restoration.

摘要

We integrate analyses of spatial association with empirical measures of juvenile performance to develop a strategy for Araucaria forest restoration in Brazil. Because pioneer species can differentially facilitate or inhibit target species, we measure native Araucaria angustifolia and exotic Pinus taeda responses to two common pioneer species, Baccharis uncinella and Vernonia discolor in a clear-cut pine plantation. P. taeda establishment and growth was greater than that of A. angustifolia in all treatments, showing its potential for invasiveness. B. uncinella showed significant positive spatial associations with P. taeda and negative spatial associations with A. angustifolia. V. discolor showed significant negative spatial associations with P. taeda but neutral spatial associations with A. angustifolia, it also supported a higher diversity of native species under its canopy than B. uncinella. Experimental results show that these patterns are due to differential establishment restrictions imposed by both pioneers on target species. We conclude that B. uncinella promotes pine invasion while V. discolor restrains it. We suggest strategies for Araucaria forest restoration and highlight the broad applicability of our approach to restoration programs.Digital Object Identifier http://dx.doi.org/10.1016/j.baae.2011.09.011