Acacia dealbata invasion in Chile: Surprises from climatic niche and species distribution models.

Bárbara Langdon,Aníbal Pauchard,Ramiro O Bustamante

doi:10.1002/ece3.5295

Abstract

AimTree invasions are a threat to biodiversity conservation, and although it is hard to predict the future spread of invasive tree species, there are tools available which could allow some estimations. The magnitude of spatial spread (a proxy of invasiveness) can be predicted from species climatic requirement (climatic niche) and can be represented by species distribution models (SDMs). We aimed to assess whether Acacia dealbata conserves its niche in the new environment of south‐central Chile, and also, to estimate the invasive stage of the species.LocationSouth‐central area of Chile, between the O'Higgins (34°0″0′S) and Aysen Regions (47°0″0′S).MethodsWe used a combination of global, native, and regional data to improve the estimation of the potential distribution of A. dealbata, which has been considered one of the most invasive species of the genus, being registered in at least 34 countries in all the Continents.ResultsOur results show that A. dealbata does not conserve its niche in the study area, invading areas with climatic conditions different from those of the native range. It is also not at equilibrium with the environment. According to the global versus regional SDM comparisons, populations present in south‐central Chile present different invasion stages. There are some stable populations, but there are other populations colonizing new areas, occupying unsuitable habitats and some of them are adapting to new climatic conditions. Climatic factors, such as precipitation seasonality, could be acting behind the expansion to new environments, and biotic factors or dispersal limitations could be preventing the species to colonize suitable areas.Main conclusionsThe invasion process of A. dealbata is far from stabilizing, and management options should focus on prevention, avoiding, for example, the introduction of the species to Patagonia where the species has not spread yet. More research is needed to complement our results and enhance the development of effective management strategies.

Highlights

Tree invasions represent a major threat to biodiversity conservation (Dickie et al, 2014; Rejmanek & Richardson, 2013; Richardson & Rejmanek, 2011; Rundel, Dickie, & Richardson, 2014)
The aim of this study was to examine the climatic niche of Acacia dealbata, (a) in the environmental space, testing for niche conservatism, using the Broennimann et al (2012) and Petitpierre et al (2012) approaches of native‐invaded niche contrasts, which will allow us to determine whether the species is establishing in south‐central Chile under the same climatic conditions it occupies in the native range, and (b) in the geographic space, testing for geographic equilibrium and the invasion stages of the species in south‐central Chile, using Gallien et al (2012) approach to compare the global and regional species distribution models (SDMs)
We aim to examine potential constraints to A. dealbata distribution in its native range using the global‐native range niche contrast, which could explain the distribution of the species in south‐central Chile

Summary

| INTRODUCTION

Tree invasions represent a major threat to biodiversity conservation (Dickie et al, 2014; Rejmanek & Richardson, 2013; Richardson & Rejmanek, 2011; Rundel, Dickie, & Richardson, 2014). The aim of this study was to examine the climatic niche of Acacia dealbata, (a) in the environmental space, testing for niche conservatism, using the Broennimann et al (2012) and Petitpierre et al (2012) approaches of native‐invaded niche contrasts, which will allow us to determine whether the species is establishing in south‐central Chile under the same climatic conditions it occupies in the native range, and (b) in the geographic space, testing for geographic equilibrium and the invasion stages of the species in south‐central Chile, using Gallien et al (2012) approach to compare the global and regional (invaded) SDM. We aim to examine potential constraints to A. dealbata distribution in its native range using the global‐native range niche contrast, which could explain the distribution of the species in south‐central Chile

| METHODS

Findings

| DISCUSSION