Centro Austral de Investigaciones Científicas (CADIC-CONICET), Ushuaia, Tierra del Fuego, Argentina.
PLoS One. 2020 Apr 24;15(4):e0232057. doi: 10.1371/journal.pone.0232057. eCollection 2020.
Quantifying the presence and environmental impact of invasive species is the starting point for research on management and nature conservation. North American beavers (Castor canadensis) were introduced to Argentina from Canada in 1946, and the species has been identified as a major agent of environmental change in the Tierra del Fuego archipelago in the Anthropocene. We studied the invasion status (distribution and density) of beavers through analyses of the dam densities in the Tierra del Fuego landscapes. We identified beaver dams with 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 factors comprised geographic (vegetation zones and distance to streams), climatic (temperature, precipitation, evapotranspiration and net primary productivity) and topographic (elevation and slope) data. The datasets (dams and factors) were combined, and the data from the different zonation classes were subsequently compared using ANOVAs and Tukey's mean comparison tests. Deviations from the mean density (x mean density-x total mean density) were calculated to visualize the deviations for the studied factors. The datasets were also evaluated using principal component analyses (PCA). Our results showed a total of 206,203 beaver dams (100,951 in Argentina and 105,252 in Chile) in the study area (73,000 km2). The main island of Tierra del Fuego presented a greater degree of invasion (73.6% of the total study area) than the rest of the archipelago, especially in areas covered by mixed-evergreen and deciduous forests. The studied geographic, climatic and topographic factors showed positive trends (higher beaver preference) with beaver spread, which were all significant (p <0.05) when compared across the landscape. Although beavers are flexible in their habitat use, our empirical records showed that they had marked preferences and were positively influenced by the most productive forests. Here, we describe a scientific panorama that identified the drivers of species invasion based on satellite data and the available ecological datasets. The identification of such drivers could be useful for developing new tools for management and/or control strategies of the beavers in the Tierra del Fuego archipelago.
量化入侵物种的存在和环境影响是管理和自然保护研究的起点。北美海狸（Castor canadensis）于 1946 年从加拿大引入阿根廷，该物种已被确定为人类世火地岛群岛环境变化的主要因素。我们通过分析火地岛景观中的水坝密度来研究海狸的入侵状况（分布和密度）。我们使用 Microsoft Bing、Google Earth 和 HERE 的高分辨率航空影像的视觉解释，通过 GIS 识别海狸水坝，并将其与自然环境梯度相关联。这些因素包括地理（植被带和与溪流的距离）、气候（温度、降水、蒸散和净初级生产力）和地形（海拔和坡度）数据。数据集（水坝和因素）合并后，使用方差分析和 Tukey 均值比较检验比较不同分区类别的数据。计算偏差（x 均值密度-x 总均值密度）以可视化研究因素的偏差。还使用主成分分析（PCA）评估数据集。我们的结果显示，在研究区域（73000 平方公里）中共有 206203 个海狸水坝（阿根廷 100951 个，智利 105252 个）。火地岛主岛的入侵程度（占总研究区域的 73.6%）高于群岛的其他地区，特别是在混合常绿和落叶林覆盖的地区。研究的地理、气候和地形因素显示出与海狸分布呈正相关（更高的海狸偏好），并且在景观之间比较时均具有显著意义（p<0.05）。尽管海狸在其生境利用方面具有灵活性，但我们的实证记录表明，它们具有明显的偏好，并受到生产力最高的森林的积极影响。在这里，我们根据卫星数据和现有的生态数据集描述了物种入侵的驱动因素的科学全景。识别这些驱动因素可能有助于开发火地岛群岛海狸管理和/或控制策略的新工具。
