Can landscape-scale characteristics be used to predict plant invasions along rivers?

Aim To determine whether the invasions of hydrochorus plants, that is those which can make use of rivers to transport their propagules, can be predicted using information derived at the landscape scale. This is desirable to avoid the need for the difficult to measure parameters required by detailed invasion models. Methods A model for plant propagule dispersal was developed that simulated both local dispersal (autochory) and aided dispersal along river corridors (hydrochory). This provided the simulated invasion behaviour that was to be predicted by the simple analytical method. This latter was based on readily available river network characteristics. The analytical summary was then tested for its ability to predict the results of a series of simulation experiments. Results Predicted dispersal rates derived from the analytical summary method were strongly correlated (R-2 of 0.8941) to the mean seed displacement simulated by the plant dispersal model. Main conclusion The simple analytical summary of the river networks provides a good probabilistic description of the simulated invasion process. This means that readily available information might be able to be used to predict real invasions by alien plant species. This method should now be tested against observed invasions by alien plants.