Feedback between drought and deforestation in the Amazon
Feedback between drought and deforestation in the Amazon
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DOI：
10.1088/1748-9326/ab738e
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发表时间：
2020-01
影响因子：
6.7
通讯作者：
A. Staal;B. Flores;A. Aguiar;J. Bosmans;I. Fetzer;O. Tuinenburg
中科院分区：
文献类型：
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作者：
A. Staal;B. Flores;A. Aguiar;J. Bosmans;I. Fetzer;O. Tuinenburg
森林砍伐和干旱是亚马逊雨林面临的最大环境压力，可能会破坏森林气候系统的稳定。亚马逊地区的森林砍伐减少了该地区的降雨量，而据报道，干旱本身也加剧了这种森林砍伐。在这里，我们量化了 21 世纪初整个亚马逊地区干旱和森林砍伐之间的相互作用。首先，我们将观察到的森林砍伐率波动与旱季强度联系起来；其次，我们确定森林改耕对蒸散量的影响；第三，我们模拟了由于大气水输入减少而导致的随后的顺风降雨量减少。我们发现森林砍伐对旱季强度的反应存在很大差异，随着旱季强度加大，森林砍伐率平均会显着但小幅增加：缺水每毫米，森林砍伐往往每年增加 0.13%。反过来，森林砍伐造成了最近观测到的干旱的 4%，其中亚马逊西南部地区受到的影响最为严重。结合这两种影响，我们量化了干旱-森林砍伐的强化反馈，该反馈目前很小，但随着森林砍伐的累积而逐渐增强。我们的研究结果表明，全球气候变化，而不是森林砍伐，是亚马逊地区近期干旱的主要原因。然而，干旱和森林砍伐之间的反馈意味着其中任何一个的增加都会阻碍遏制这两者的努力。
Deforestation and drought are among the greatest environmental pressures on the Amazon rainforest, possibly destabilizing the forest-climate system. Deforestation in the Amazon reduces rainfall regionally, while this deforestation itself has been reported to be facilitated by droughts. Here we quantify the interactions between drought and deforestation spatially across the Amazon during the early 21st century. First, we relate observed fluctuations in deforestation rates to dry-season intensity; second, we determine the effect of conversion of forest to cropland on evapotranspiration; and third, we simulate the subsequent downwind reductions in rainfall due to decreased atmospheric water input. We find large variability in the response of deforestation to dry-season intensity, with a significant but small average increase in deforestation rates with a more intense dry season: with every mm of water deficit, deforestation tends to increase by 0.13% per year. Deforestation, in turn, has caused an estimated 4% of the recent observed drying, with the south-western part of the Amazon being most strongly affected. Combining both effects, we quantify a reinforcing drought-deforestation feedback that is currently small, but becomes gradually stronger with cumulative deforestation. Our results suggest that global climate change, not deforestation, is the main driver of recent drying in the Amazon. However, a feedback between drought and deforestation implies that increases in either of them will impede efforts to curb both.