Multi-Dimensional Remote Sensing Analysis Documents Beaver-Induced Permafrost Degradation, Seward Peninsula, Alaska
Multi-Dimensional Remote Sensing Analysis Documents Beaver-Induced Permafrost Degradation, Seward Peninsula, Alaska
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DOI：
10.3390/rs13234863
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发表时间：
2021-12-01
期刊：
影响因子：
5
通讯作者：
Miller, Charles E.
中科院分区：
文献类型：
--
作者：
Jones, Benjamin M.;Tape, Ken D.;Miller, Charles E.
在过去的几十年里，海狸已经将自己确立为低北极生态系统的关键组成部分。海狸被广泛认为是生态系统工程师，但它们对北极以永久冻土为主的地貌的影响尚不清楚。在这项研究中，我们利用卫星(Landsat-8、Sentinel-2、Planet CubeSat和DigitalGlobe Inc./MAXAR)和无人机系统(UAS)图像的多维遥感分析，记录了海狸活动的发生，重建了时间，并强调了海狸活动对阿拉斯加州西沃德半岛一个被富冰永久冻土限制的小溪谷的影响。2006年至2011年间，随着三座水坝的修建，天鹅湖小溪研究河段出现了海狸活动。2011至2017年间，河狸水坝数量增加，高峰出现在2017年(n=9)。2017年至2019年，大坝数量减少(n=6)，而大坝的平均长度从20米增加到33米。2019年8月4日至20日，在经历了9天的创纪录降雨量(125毫米)后，完善的大坝系统崩溃，引发了由海狸引发的永久冻土退化特征的形成。在2011年至2021年期间，由于河狸工程和河狸引起的永久冻土退化，溪谷从33米扩大到180米(增加了~450%)，河网长度从大约0.6公里增加到超过1.9公里(增加了220%)。从2017至2021年间获得的关于海狸引起的永久冻土退化特征的时间序列数据和附近一个未受影响的对照地点的植被指数(NDVI)和降雪指数(NDSI)进行比较，结果表明，在多年冻土干扰之后，生长高峰期NDVI降低了23%，并将雪盖期延长了19天。我们对多维遥感数据的分析突出了海狸工程对富含冰的永久冻土景观的几个独特方面的影响。我们对海狸诱导的永久冻土退化事件的详细重建也可能被证明有助于在区域尺度上在光学时间序列数据集中识别富冰永久冻土的退化。未来对这个地点和其他类似地点的实地和遥感观测，将为美国国家科学基金会资助的北极海狸观测网络(A-BON)和NASA北极-北方脆弱性实验(上图)实地活动的第三阶段提供有价值的信息。
Beavers have established themselves as a key component of low arctic ecosystems over the past several decades. Beavers are widely recognized as ecosystem engineers, but their effects on permafrost-dominated landscapes in the Arctic remain unclear. In this study, we document the occurrence, reconstruct the timing, and highlight the effects of beaver activity on a small creek valley confined by ice-rich permafrost on the Seward Peninsula, Alaska using multi-dimensional remote sensing analysis of satellite (Landsat-8, Sentinel-2, Planet CubeSat, and DigitalGlobe Inc./MAXAR) and unmanned aircraft systems (UAS) imagery. Beaver activity along the study reach of Swan Lake Creek appeared between 2006 and 2011 with the construction of three dams. Between 2011 and 2017, beaver dam numbers increased, with the peak occurring in 2017 (n = 9). Between 2017 and 2019, the number of dams decreased (n = 6), while the average length of the dams increased from 20 to 33 m. Between 4 and 20 August 2019, following a nine-day period of record rainfall (>125 mm), the well-established dam system failed, triggering the formation of a beaver-induced permafrost degradation feature. During the decade of beaver occupation between 2011 and 2021, the creek valley widened from 33 to 180 m (~450% increase) and the length of the stream channel network increased from ~0.6 km to more than 1.9 km (220% increase) as a result of beaver engineering and beaver-induced permafrost degradation. Comparing vegetation (NDVI) and snow (NDSI) derived indices from Sentinel-2 time-series data acquired between 2017 and 2021 for the beaver-induced permafrost degradation feature and a nearby unaffected control site, showed that peak growing season NDVI was lowered by 23% and that it extended the length of the snow-cover period by 19 days following the permafrost disturbance. Our analysis of multi-dimensional remote sensing data highlights several unique aspects of beaver engineering impacts on ice-rich permafrost landscapes. Our detailed reconstruction of the beaver-induced permafrost degradation event may also prove useful for identifying degradation of ice-rich permafrost in optical time-series datasets across regional scales. Future field- and remote sensing-based observations of this site, and others like it, will provide valuable information for the NSF-funded Arctic Beaver Observation Network (A-BON) and the third phase of the NASA Arctic-Boreal Vulnerability Experiment (ABoVE) Field Campaign.