Department of Geography and Planning, and Global Institute for Water Security, University of Saskatchewan, Saskatoon, Saskatchewan, Canada.
Department of Forest and Rangeland Stewardship and Graduate Degree Program in Ecology, Colorado State University, Fort Collins, CO, USA.
Sci Total Environ. 2017 Jan 1;574:183-190. doi: 10.1016/j.scitotenv.2016.09.045. Epub 2016 Oct 14.
The North American beaver (Castor canadensis) is an invasive species in southern Patagonia, introduced in 1946 as part of a program by the Argentine government to augment furbearers. Research focus has turned from inventorying the beaver's population and ecosystem impacts toward eradicating it from the region and restoring degraded areas. Successful restoration, however, requires a fuller determination of how beavers have altered physical landscape characteristics, and of what landscape features and biota need to be restored. Our goal was to identify changes to the physical landscape by invasive beaver. We analyzed channel and valley morphology in detail at one site in each of the three major forest zones occurring on the Argentine side of Tierra del Fuego's main island. We also assessed 48 additional sites across the three forest biomes on the island to identify a broader range of aquatic habitat occupied and modified by beaver. Beaver build dams with Nothofagus tree branches on streams, which triggered mineral sediment accretion processes in the riparian zone, but not in ways consistent with the beaver meadow theory and only at a few sites. At the majority of sites, beavers actively excavated peat and mineral sediment, moved thousands of cubic meters of sediment within their occupied landscapes and used it to build dams. Beaver were also common in fen ecosystems where pond formation inundated and drowned peat forming mosses and sedges, and triggered a massive invasion of exotic plant species. Results highlight that restoration of fen ecosystems is a previously unrecognized but pressing and challenging restoration need in addition to reforestation of Nothofagus riparian forests. We recommend that decision-makers include the full ecosystem diversity of the Fuegian landscape in their beaver eradiation and ecosystem restoration plans.
北美海狸（Castor canadensis）是巴塔哥尼亚南部的入侵物种，于 1946 年作为阿根廷政府增加皮毛兽计划的一部分引入。研究重点已从清查海狸的种群和对生态系统的影响，转向从该地区消灭海狸并恢复退化地区。然而，成功的恢复需要更全面地确定海狸如何改变了物理景观特征，以及需要恢复哪些景观特征和生物区系。我们的目标是确定入侵海狸对物理景观的改变。我们在火地岛阿根廷一侧的三个主要森林区的每个区的一个地点详细分析了河道和山谷形态。我们还评估了岛上三个森林生物群落的 48 个额外地点，以确定海狸占据和改造的更广泛的水生栖息地。海狸用山毛榉树枝在溪流上筑坝，这引发了河流带的矿物沉积物堆积过程，但与海狸草地理论不一致，而且只在少数几个地点发生。在大多数地点，海狸积极挖掘泥炭和矿物沉积物，在其占据的景观内移动了数千立方米的沉积物，并将其用于筑坝。海狸在沼泽生态系统中也很常见，那里的池塘形成淹没并淹死了形成泥炭的苔藓和莎草，引发了外来植物物种的大规模入侵。研究结果表明，除了重新造林山毛榉河岸林之外，恢复沼泽生态系统是一项以前未被认识但紧迫而具有挑战性的恢复需求。我们建议决策者在其消灭海狸和生态系统恢复计划中包括火地岛景观的完整生态系统多样性。
