Carbon emissions from agricultural expansion and intensification in the Chaco
Carbon emissions from agricultural expansion and intensification in the Chaco
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DOI：
10.1111/gcb.13521
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发表时间：
2017-05-01
影响因子：
11.6
通讯作者：
Kuemmerle, Tobias
中科院分区：
文献类型：
--
作者：
Baumann, Matthias;Gasparri, Ignacio;Kuemmerle, Tobias
人们对热带干燥森林系统土地利用变化的碳排放知之甚少，尽管它们可能在全球范围内产生重大影响。随着养牛场和大豆种植扩展到森林，以及大豆种植取代牧场，南美查科最近已成为农业扩张和集约化的热点。尽管如此，我们对这些土地利用变化的速度和空间模式以及它们如何影响碳排放的了解仍然不全面。我们使用陆地卫星卫星图像档案重建了过去30年的土地利用变化，并应用了碳簿记模型来量化这些变化如何影响碳收支。从1985年到2013年，超过14.2万公里(2)的查科森林被农田(38.9%)或牧场(61.1%)取代，相当于森林总面积的20%。在1985年存在的牧场中，约有40%后来变成了农田。这些土地利用变化导致了大量的碳排放，1985至2013年间总计824 TgC，仅2013年就达到46.2TgC。其中大部分排放来自森林到牧场的转变(68%)，但毁林后土地利用的变化引发了额外的52.6TG C。尽管热带干燥森林的碳密度低于潮湿的热带森林，但查科地区土地利用变化的碳排放量与其他主要热带砍伐边界的碳排放量相似。因此，我们的研究突出了迫切需要改进对经常被忽视的热带干燥森林和稀树草原的监测，以及更广泛地说，陆地卫星图像档案在量化土地变化的碳通量方面的价值。
Carbon emissions from land-use changes in tropical dry forest systems are poorly understood, although they are likely globally significant. The South American Chaco has recently emerged as a hot spot of agricultural expansion and intensification, as cattle ranching and soybean cultivation expand into forests, and as soybean cultivation replaces grazing lands. Still, our knowledge of the rates and spatial patterns of these land-use changes and how they affected carbon emissions remains partial. We used the Landsat satellite image archive to reconstruct land-use change over the past 30 years and applied a carbon bookkeeping model to quantify how these changes affected carbon budgets. Between 1985 and 2013, more than 142 000 km(2) of the Chaco's forests, equaling 20% of all forest, was replaced by croplands (38.9%) or grazing lands (61.1%). Of those grazing lands that existed in 1985, about 40% were subsequently converted to cropland. These land-use changes resulted in substantial carbon emissions, totaling 824 Tg C between 1985 and 2013, and 46.2 Tg C for 2013 alone. The majority of these emissions came from forest-to-grazing-land conversions (68%), but post-deforestation land-use change triggered an additional 52.6 Tg C. Although tropical dry forests are less carbon-dense than moist tropical forests, carbon emissions from land-use change in the Chaco were similar in magnitude to those from other major tropical deforestation frontiers. Our study thus highlights the urgent need for an improved monitoring of the often overlooked tropical dry forests and savannas, and more broadly speaking the value of the Landsat image archive for quantifying carbon fluxes from land change.