Bárbara Langdon1,2, Aníbal Pauchard1,2 and Ramiro O. Bustamante2,3
1Laboratorio de Invasiones Biológicas (LIB), Facultad de Ciencias Forestales, Universidad de Concepción, Victoria 631, Barrio Universitario, Concepción, Chile
2Instituto de Ecología y Biodiversidad (IEB), Chile
3Laboratorio de Ecología Geográfica, Facultad de Ciencias, Universidad de Chile, Santiago, Chile
Tree invasions are a threat to biodiversity conservation and although it is difficult to predict the future spread of invasive tree species, there are tools available which could allow some estimations. The last report on Chilean Forest Resources, shows that commercial plantations reach 2,447,591 ha, with P. radiata (1,469,718 ha), E. globulus (563,813 ha), Eucalyptus nitens (246,726 ha), Pinus ponderosa (27,775 ha), and Pseudotsuga menziesii (16,222 ha) among the main planted species. The same report indicates that according to annual plantation surface, P. radiata is still the most planted species, followed by Eucalyptus species, located mostly in the South-Central Regions of Chile.
We aimed to (i) assess whether forestry species, such as Eucalyptus globulus, Eucalyptus grandis, Eucalyptus nitens, Pinus contorta, Pinus ponderosa, Pinus radiata and Pseudotsuga menziesii, used with commercial purposes in South-Central Chile, conserve their niche in the new environment, and (ii) estimate the invasion stage of each species. Bioclimatic variables and occurrences at the native and the invaded (i.e. South-central Chile) ranges were used to elucidate whether climatic niche requirements are conserved (or not) in the invaded region, and whether the distribution has allowed a geographical equilibrium in the invaded range. Global and Regional (South-central Chile) Species Distribution Models (SDM) were constructed to discern what fraction of the fundamental niche is expressed in the invaded range. Results showed that the Global SDM has a significantly better fit than the regional or native SDMs. From the seven species assessed, none of them are at equilibrium with the environment, and only two of them, Pinus contorta and Pseudotsuga menziesii, conserve their climatic niche. The same trend is shown in the global-regional comparison. Populations from the studied species, are far from stabilizing, with a high proportion of them establishing outside the predicted areas.
According to our results, these forestry species are in an early stage of the invasion process in Chile, when comparing with the situation registered in other regions. This opens an opportunity to avoid major impacts, which should reduce managing costs. These results are fundamental keys to develop biosecurity tools, which will allow decision makers and managers to prioritize between species and areas to manage invasions, enhancing efficiency of management activities.