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Keywords:

  • Exotic plants;
  • Facilitation;
  • Invasion;
  • Mediterranean climate-type ecosystem;
  • Restoration;
  • Sclerophyllous forest

Abstract

Question

What is the effect of invading individuals of the widely invasive species Pinus radiata D. Don on regeneration of native woody species in a semi-arid ecosystem?

Location

A semi-arid ecosystem in central Chile.

Methods

We sampled natural regeneration of native woody species in 40 plots in each of three canopy types: (1) under young adult invading trees of Pradiata located in formerly open (disturbed) sites; (2) in patches of native trees; and (3) in open (disturbed) sites, in two localities where this exotic tree is invading. Additionally, we carried out a field experiment in one of these localities; in eight of each of these canopy types we sowed seeds of ten widely distributed woody native species and monitored their recruitment. We also assessed different biotic and abiotic variables in these canopy types.

Results

We found that soil water content, depth and cover of leaf litter were higher and photosythetically active radiation was lower under P. radiata trees and native patches than in open sites. In the natural regeneration study, species richness of seedlings was higher in native patches and under P. radiata trees than in open sites, and total abundance of seedlings (including all species) was higher only in native patches than in open sites. In the field experiment, both species richness and total abundance of seedlings were higher in native patches and under P. radiata trees than in open sites. Moreover, in the field experiment species richness recruiting in native patches was higher than under P. radiata trees.

Conclusions

We suggest that native patches as well as P. radiata trees invading open sites facilitate or have the potential to facilitate regeneration of native species, although facilitation produced by native trees was stronger than that produced by P. radiata. Thus, in sites where nurse plants are not available, invasion by this exotic tree may be exploited in restoration processes through sowing or planting native species under the canopy of invading young trees of P. radiata, eliminating P. radiata individuals after native regeneration has established.