Mapping the status of the North American beaver invasion in the Tierra del Fuego archipelago.

A HUERTAS HERRERA; MV LENCINAS; M TORO; JA MILLER; G MARTÍNEZ PASTUR

PLOS ONE

PUBLIC LIBRARY SCIENCE

Lugar: San Francisco; Año: 2020 vol. 15 p. 232057 - 232057

1932-6203

Quantifying the presence and environmental impact of invasive species is the starting pointfor research on management and nature conservation. North American beavers (Castorcanadensis) were introduced to Argentina from Canada in 1946, and the species has beenidentified as a major agent of environmental change in the Tierra del Fuego archipelago in theAnthropocene. We studied the invasion status (distribution and density) of beavers throughanalyses of the dam densities in the Tierra del Fuego landscapes. We identified beaver damswith a GIS using visual interpretation of high-resolution aerial imagery from Microsoft Bing,Google Earth and HERE and related them to natural environmental gradients. These factorscomprised geographic (vegetation zones and distance to streams), climatic (temperature,precipitation, evapotranspiration and net primary productivity) and topographic (elevation andslope) data. The datasets (dams and factors) were combined, and the data from the differentzonation classes were subsequently compared using ANOVAs and Tukey?s mean comparisontests. Deviations from the mean density (x mean density?x total mean density) were calculatedto visualize the deviations for the studied factors. The datasets were also evaluatedusing principal component analyses (PCA). Our results showed a total of 206,203 beaverdams (100,951 in Argentina and 105,252 in Chile) in the study area (73,000 km2). The mainisland of Tierra del Fuego presented a greater degree of invasion (73.6% of the total studyarea) than the rest of the archipelago, especially in areas covered by mixed-evergreen anddeciduous forests. The studied geographic, climatic and topographic factors showed positivetrends (higher beaver preference) with beaver spread, which were all significant (p