Satellite-based estimates reveal widespread forest degradation in the Amazon
Satellite-based estimates reveal widespread forest degradation in the Amazon
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DOI：
10.1111/gcb.15029
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发表时间：
2020-05-01
影响因子：
11.6
通讯作者：
Olofsson, Pontus
中科院分区：
文献类型：
--
作者：
Bullock, Eric L.;Woodcock, Curtis E.;Olofsson, Pontus
人为和天然林干扰造成生态破坏和碳排放。亚马逊地区的森林干扰形式包括砍伐森林（森林变成非森林土地覆盖）、森林资源开采造成的退化以及自然事件造成的破坏。亚马逊雨林在水文循环中的关键作用甚至导致人们猜测，一个扰动“临界点”会导致热带生态系统的崩溃。在这里，我们使用Landsat数据的时间序列分析来绘制1995年至2017年亚马逊生态区的森林砍伐，退化和自然干扰。该地图被用来对研究区域进行分层，以选择根据土地覆盖和扰动历史分配参考标签的样本单位。对参考观测样本采用了无偏统计估计数，以获得两年期时间间隔的面积和不确定性估计数。我们发现，退化和自然干扰，主要是在严重干旱期间，对亚马逊生态区森林面积的影响与1995年至2017年的森林砍伐一样大。因此，截至2017年，估计有17%（1，036，800 +/-24，800 km（2），95%置信区间）的原始森林面积受到干扰。我们的研究结果表明，亚马逊地区受干扰的森林面积比以前认识到的多44%-60%，这表明碳排放源不明，森林生态系统受到普遍破坏。
Anthropogenic and natural forest disturbance cause ecological damage and carbon emissions. Forest disturbance in the Amazon occurs in the form of deforestation (conversion of forest to non-forest land covers), degradation from the extraction of forest resources, and destruction from natural events. The crucial role of the Amazon rainforest in the hydrologic cycle has even led to the speculation of a disturbance "tipping point" leading to a collapse of the tropical ecosystem. Here we use time series analysis of Landsat data to map deforestation, degradation, and natural disturbance in the Amazon Ecoregion from 1995 to 2017. The map was used to stratify the study area for selection of sample units that were assigned reference labels based on their land cover and disturbance history. An unbiased statistical estimator was applied to the sample of reference observations to obtain estimates of area and uncertainty at biennial time intervals. We show that degradation and natural disturbance, largely during periods of severe drought, have affected as much of the forest area in the Amazon Ecoregion as deforestation from 1995 to 2017. Consequently, an estimated 17% (1,036,800 +/- 24,800 km(2), 95% confidence interval) of the original forest area has been disturbed as of 2017. Our results suggest that the area of disturbed forest in the Amazon is 44%-60% more than previously realized, indicating an unaccounted for source of carbon emissions and pervasive damage to forest ecosystems.