Increase in beaver dams controls surface water and thermokarst dynamics in an Arctic tundra region, Baldwin Peninsula, northwestern Alaska
Increase in beaver dams controls surface water and thermokarst dynamics in an Arctic tundra region, Baldwin Peninsula, northwestern Alaska
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DOI：
10.1088/1748-9326/ab80f1
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发表时间：
2020-07-01
影响因子：
6.7
通讯作者：
Disbrow, Jeff
中科院分区：
文献类型：
--
作者：
Jones, Benjamin M.;Tape, Ken D.;Disbrow, Jeff
海狸开始在阿拉斯加和加拿大的低北极苔原地区定居，这对地表水的变化和富含冰的永久冻土的退化有影响。在这项研究中，我们利用2002年至2019年期间获得的阿拉斯加西北部两个冻土带地区的亚米分辨率卫星图像，评估了海狸大坝建设与地表水动力学和热岩溶地貌相关的时空动态。在Kotzebue附近一个100公里（2公里）的研究区域，2002年至2019年间，水坝的数量从2个显著增加到98个。在涵盖整个鲍德温半岛北部的430公里(2)研究区域内，2010年至2019年间，水坝数量从94座增加到409座，表明了区域趋势。将2002年至2019年Kotzebue研究区12个单独年份的海狸坝数量与地表水面积的相关数据显示出显著的正相关（R-2= 0.61; p < 0.003）。在17年期间，Kotzebue研究区总地表水面积增加了8.3%，受海狸影响的水体占了其中的三分之二。海狸在筑坝活动中特别针对热岩溶地貌。排水热岩溶湖流域的洪水占海狸影响地表水增加的68%，湖泊出水口筑坝占26%，珠流筑坝占6%。海狸筑坝导致的地表水增加可能加剧了该地区永久冻土的退化，但大坝的破坏也影响了鲍德温半岛北部研究地区几个热岩溶湖的排水，这可能会促进新暴露的湖泊沉积物中局部永久冻土的恶化。我们的研究结果强调，在考虑某些永久冻土区发生的变化时，必须仔细考虑海狸驱动的生态系统工程，特别是低北极和北方景观的区域地表水动态。
Beavers are starting to colonize low arctic tundra regions in Alaska and Canada, which has implications for surface water changes and ice-rich permafrost degradation. In this study, we assessed the spatial and temporal dynamics of beaver dam building in relation to surface water dynamics and thermokarst landforms using sub-meter resolution satellite imagery acquired between 2002 and 2019 for two tundra areas in northwestern Alaska. In a 100 km(2)study area near Kotzebue, the number of dams increased markedly from 2 to 98 between 2002 and 2019. In a 430 km(2)study area encompassing the entire northern Baldwin Peninsula, the number of dams increased from 94 to 409 between 2010 and 2019, indicating a regional trend. Correlating data on beaver dam numbers with surface water area mapped for 12 individual years between 2002 and 2019 for the Kotzebue study area showed a significant positive correlation (R-2= 0.61; p < .003). Beaver-influenced waterbodies accounted for two-thirds of the 8.3% increase in total surface water area in the Kotzebue study area during the 17 year period. Beavers specifically targeted thermokarst landforms in their dam building activities. Flooding of drained thermokarst lake basins accounted for 68% of beaver-influenced surface water increases, damming of lake outlets accounted for 26%, and damming of beaded streams accounted for 6%. Surface water increases resulting from beaver dam building likely exacerbated permafrost degradation in the region, but dam failure also factored into the drainage of several thermokarst lakes in the northern Baldwin Peninsula study region, which could promote local permafrost aggradation in freshly exposed lake sediments. Our findings highlight that beaver-driven ecosystem engineering must be carefully considered when accounting for changes occurring in some permafrost regions, and in particular, regional surface water dynamics in low Arctic and Boreal landscapes.