We have some experience were I live, with two alien plants introduced during the twentieth century in Northwest Spain: Acacia dealbata and Eucalyptus. First introduced by a monk, Fray Rosendo Salvado, eucalyptus was favoured by the Franco dictatorship as a means of growing wood fast; Thanks to this two luminaries the habitat of Galicia has been severely damaged, many think for centuries to come. Both -Acacia dealbata and Eucalyptus- make up for excellent fire fuel, during the dry season, apart from the acidification of the soil. Not to mention the harm done to the native species.
So good luck playing god.