Wageningen Environmental Research, Climate Resilience Team, Wageningen University & Research, Wageningen, the Netherlands.
Environmental Systems Analysis Group, Wageningen University, Wageningen, the Netherlands.
Glob Chang Biol. 2023 Sep;29(18):5292-5303. doi: 10.1111/gcb.16856. Epub 2023 Jul 5.
Despite recent advances in modeling forest-rainfall relationships, the current understanding of changes in observed rainfall patterns resulting from historical deforestation remains limited. To address this knowledge gap, we analyzed how 40 years of deforestation has altered rainfall patterns in South America as well as how current Amazonian forest cover sustains rainfall. First, we develop a spatiotemporal neural network model to simulate rainfall as a function of vegetation and climate inputs in South America; second, we assess the rainfall effects of observed deforestation in South America during the periods 1982-2020 and 2000-2020; third, we assess the potential rainfall changes in the Amazon biome under two deforestation scenarios. We find that, on average, cumulative deforestation in South America from 1982 to 2020 has reduced rainfall over the period 2016-2020 by 18% over deforested areas, and by 9% over non-deforested areas across South America. We also find that more recent deforestation, that is, from 2000 to 2020, has reduced rainfall over the period 2016-2020 by 10% over deforested areas and by 5% over non-deforested areas. Deforestation between 1982 and 2020 has led to a doubling in the area experiencing a minimum dry season of 4 months in the Amazon biome. Similarly, in the Cerrado region, there has been a corresponding doubling in the area with a minimum dry season of 7 months. These changes are compared to a hypothetical scenario where no deforestation occurred. Complete conversion of all Amazon forest land outside protected areas would reduce average annual rainfall in the Amazon by 36% and complete deforestation of all forest cover including protected areas would reduce average annual rainfall in the Amazon by 68%. Our findings emphasize the urgent need for effective conservation measures to safeguard both forest ecosystems and sustainable agricultural practices.
尽管在模拟森林与降雨关系方面取得了最新进展，但对于历史上森林砍伐导致观测到的降雨模式变化的理解仍然有限。为了弥补这一知识空白，我们分析了 40 年来森林砍伐如何改变南美洲的降雨模式，以及当前亚马逊地区的森林覆盖如何维持降雨。首先，我们开发了一个时空神经网络模型，以模拟南美洲植被和气候输入与降雨之间的关系；其次，我们评估了 1982 年至 2020 年和 2000 年至 2020 年期间南美洲观测到的森林砍伐对降雨的影响；第三，我们评估了在两种森林砍伐情景下亚马逊生物群落的潜在降雨变化。我们发现，平均而言，1982 年至 2020 年期间南美洲的累计森林砍伐使 2016 年至 2020 年期间森林砍伐区的降雨量减少了 18%，而非森林砍伐区的降雨量减少了 9%。我们还发现，最近的森林砍伐，即 2000 年至 2020 年期间，使 2016 年至 2020 年期间森林砍伐区的降雨量减少了 10%，而非森林砍伐区的降雨量减少了 5%。1982 年至 2020 年期间的森林砍伐使亚马逊生物群落中经历最小旱季 4 个月的面积增加了一倍。同样，在塞拉多地区，经历最小旱季 7 个月的面积也相应增加了一倍。这些变化与假设没有森林砍伐发生的情景进行了比较。如果所有亚马逊林地都不被砍伐，亚马逊地区的年平均降雨量将减少 36%；如果所有森林包括保护区都被砍伐，亚马逊地区的年平均降雨量将减少 68%。我们的研究结果强调了迫切需要采取有效的保护措施，以维护森林生态系统和可持续农业实践。
