Factors associated with woody alien species distribution in a newly invaded mountain system of central Argentina

GIORGIS, M.; TECCO, P.; CINGOLANI, A.M.; RENISON, D.; MARCORA, P.; PAIARO, V.

BIOLOGICAL INVASIONS

SPRINGER

Año: 2011 vol. 13 p. 1423 - 1434

1387-3547

To help determine the major factors associated with alien plant occurrence in a scarcely invaded mountain range, we analyzed woody alien species occurrence in the Córdoba mountains, in relation to biotic, abiotic and anthropogenic factors including indicators of propagule pressure. We selected 303 plots using a Geographic Information System (GIS) covering all the variability of these factors. In the field we registered woody alien occurrence in these 303 and in 303 additional neighbor plots. We used 12 biotic, abiotic and anthropogenic variables from the GIS to predict presences of alien species through a logistic model. Then, we analyzed if neighbor alien occurrences could explain some additional variance. We created a probability map with 4 categories of alien occurrence which was then validated by new field sampling. Occurrence of woody aliens was highest in the eastern slope wich had a longer history of species introductions, at low altitudes, near sources of propagule pressure (human settlements, roads and neighbor sites with established alien plants), and associated to sheltered topographies. In the upper belt of the Córdoba Mountains woody invasion is incipient and thus in a transient stage. Accordingly, propagule pressure seems to be the major factor at play, together with altitude and topography, while the relevance of disturbance and biotic interactions is less clear.