Pine invasions: climate predicts invasion success; something else predicts failure

Aim Explaining why some invasions fail while others succeed is a prevailing question in invasion biology. Different factors have been proposed to explain the success or failure of exotics. Evidence suggests that climate similarities may be crucial. We tested this using 12 species of the genus Pinus that have been widely planted and shown to be highly invasive. Pinus is among the best-studied group of exotic species and one that has been widely introduced world-wide, so we were able to obtain data on invasive and non-invasive introductions (i.e. unsuccessful invasions; areas where after many decades of self-sowing seeds there is no invasion). Location World-wide. Methods We developed species distribution models for native ranges using a maximum entropy algorithm and projected them across the globe. We tested whether climate-based models were able to predict both invasive and non-invasive introductions. Results Appropriate climatic conditions seem to be required for these long-lived species to invade because climates accurately predicted invasions. However, climate matching is necessary, but not sufficient to predict the fate of an introduction because most non-invasive introductions were predicted to have triggered an invasion. Main conclusions Other factors, possibly including biotic components, may be the key to explaining why some introductions do not become invasions, because many areas where Pinus is not invading were predicted to be suitable for invasion based solely on climate.