Alien plant species along altitudinal gradients in North-Western Patagonia.

SPEZIALE, K.L., WERENKRAUT, V. Y EZCURRA, C.

San Carlos de Bariloche, Argentina

Congreso; VI SOUTHERN CONNECTION CONGRESS; 2010

Alien plant invasion had not historically affected high elevations but is currently reaching mountain tops. We analyzed the pattern of alien plants species richness along an altitudinal gradient, its association to environmental variables and described basic characteristics of alien species and composition along the gradient. Within Nahuel Huapi national park in northwestern Patagonia we climbed 5 mountains setting 100m2 plots every 100 m of elevation from bottom to top (range 800-2000 m.a.s.l.). In each plot we recorded every vascular plant species, habitat type, collected soil samples and mounted a temperature and humidity sensor. Most of the alien species were original from Eurasia and are regular invaders elsewhere. Many species were recorded at lower elevations than what is found for other areas of Argentina and some others at higher elevations than previously found. Clearly alien species richness decreased from bottom to top of the mountains. GLM analyses showed a positive association to native species richness and shrubland habitats, but a negative one to shrub cover and altitude. Lowland diverse habitats support more alien species than mountain tops of north-western Patagonia, which are not yet severely threatened by alien plants invasions yet. This is probably attributably to the lack of propagules given that several species were already recorded at higher altitudes. Given the current increase in mountain outdoor activities precautionary management is required to prevent future invasions.