Recent trends in African fires driven by cropland expansion and El Nino to La Nina transition
Recent trends in African fires driven by cropland expansion and El Nino to La Nina transition
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DOI：
10.1038/nclimate2313
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发表时间：
2014-09-01
影响因子：
30.7
通讯作者：
van der werf, Guido R.
中科院分区：
文献类型：
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作者：
Andela, Niels;van der werf, Guido R.
景观火灾是非洲生态系统的关键（1-3），非洲大陆占全球火灾面积的70%，占火灾相关碳排放的50%（4，5）。火灾大多是人为点燃的，但降水模式决定了火灾发生的时间和地点（6）。人类和降水在推动火烧区时空变化方面的相对作用尚未完全解开，但需要预测未来的火烧区（7，8）。在2001-2012年期间，观察表明非洲半球出现了强烈但相反的趋势（4）。在这里，我们使用卫星数据和统计模型，表明厄尔尼诺/南方涛动（ENSO）驱动的降水变化（在我们的研究期间从厄尔尼诺现象转变为拉尼娜现象占主导地位）对降水量的变化做出了重大贡献（51%）南部非洲的上升趋势。这也导致了北方非洲（24%）的下降趋势，但在这里，人口和社会经济的快速变化几乎同样重要（20%），主要是由于萨凡纳转化为农田，减少了烧毁面积。考虑到非洲的经济前景和厄尔尼诺/南方涛动的振荡性质，未来非洲萨凡纳烧毁面积可能会下降。结合由于气候变化而导致的全球森林火灾活动增加（9-11），我们的研究结果表明，全球热地理学可能从热带萨凡纳为主转变为森林为主。
Landscape fires are key in African ecosystems(1-3) and the continent is responsible for similar to 70% of global burned area and similar to 50% of fire-related carbon emissions(4,5). Fires are mostly human ignited, but precipitation patterns govern when and where fires can occur(6). The relative role of humans and precipitation in driving the spatio-temporal variability in burned area is not fully disentangled but is required to predict future burned area(7,8). Over 2001-2012, observations indicate strong but opposing trends in the African hemispheres(4). Here we use satellite data and statistical modelling and show that changes in precipitation, driven by the El Nino/Southern Oscillation (ENSO), which changed from El Nino to La Nina dominance over our study period, contributed substantially (51%) to the upward trend over southern Africa. This also contributed to the downward trend over northern Africa (24%), but here rapid demographic and socio-economic changes were almost as important (20%), mainly due to conversion of savannah into cropland, muting burned area. Given the economic perspective of Africa and the oscillative nature of ENSO, future African savannah burned area will probably decline. Combined with increasing global forest fire activity due to climate change(9-11), our results indicate a potential shift in global pyrogeography from being savannah dominated to being forest dominated.