Conditions affecting introduced Alnus sp. (Betulaceae) invasion in two patagonic National Parks

EDWARDS, P.; RELVA, M.A.; NUÑEZ, M.

Mar del Plata

Congreso; 2nd World Conference on Biological Invasions and Ecosystem Functioning; 2011

Grupo de Investigación y Educación en Temas Ambientales

Alnus species (Betulaceae) invasion process were described only with little ditail. Thus, fourteen potential invasion foci of Alders (Alnus sp.) were studied in the lakeshores of three lakes in two National Parks of Northern Patagonia in Argentina (6 in Nahuel Huapí National Park and 8 in Lanín National Park). Intrinsic population’s characteristics (maximum age, age heterogeneity, number of alder species, number of initial propagules, and percentage of reproductive individuals) and riparian habitat’s characteristics (surrounding vegetation, woody debris cover, rocks diametric classes cover, riparian zone extension and orientation) were correlated to the invasion potential (occupied area, total basal area and density) . Maximum age, age heterogeneity and percentage of reproductive individuals were related significantly to the invasion potential. Likewise, the population’s structure analysis showed that there is no intense recruitment; therefore the populations could be into a naturalization stage (i.e. colonization limited to areas adjacent to the introduction site) but not invading (colonization in areas distant from the introduction site and in high densities). The permanence of the populations in this previous stage to invasion may be owed to the time that passed since the initial introduction, and/or because some habitat characteristics such as competition, herbivory and soil properties could be conferring some current invasion resistance to the environment. Nonetheless, these alder populations should be erradicated or considered as potential invasion foci because the invasion process could be triggered after some time period or after some key disturbance.