Amazonian rainforest is undergoing increasing rates of deforestation, driven primarily by cattle pasture expansion. Forest-to-pasture conversion has been associated with increases in soil methane (CH₄) emission. To better understand the drivers of this change, we measured soil CH₄ flux, environmental conditions, and belowground microbial community structure across primary forests, cattle pastures, and secondary forests in two Amazonian regions. We show that pasture soils emit high levels of CH₄ (mean: 3454.6 ± 9482.3 μg CH₄ m⁻² d⁻¹), consistent with previous reports, while forest soils on average emit CH₄ at modest rates (mean: 9.8 ± 120.5 μg CH₄ m⁻² d⁻¹), but often act as CH₄ sinks. We report that secondary forest soils tend to consume CH₄ (mean: −10.2 ± 35.7 μg CH₄ m⁻² d⁻¹), demonstrating that pasture CH₄ emissions can be reversed. We apply a novel computational approach to identify microbial community attributes associated with flux independent of soil chemistry. While this revealed taxa known to produce or consume CH₄ directly (i.e. methanogens and methanotrophs, respectively), the vast majority of identified taxa are not known to cycle CH₄. Each land use type had a unique subset of taxa associated with CH₄ flux, suggesting that land use change alters CH₄ cycling through shifts in microbial community composition. Taken together, we show that microbial composition is crucial for understanding the observed CH₄ dynamics and that microorganisms provide explanatory power that cannot be captured by environmental variables.

亚马逊雨林的砍伐速度越来越快，这主要是由于牛牧场的扩张。森林到草场的转化与土壤甲烷（CH ₄）排放的增加有关。为了更好地了解这种变化的驱动因素，我们在两个亚马逊地区的原始森林，牛牧场和次生森林中测量了土壤CH ₄流量，环境条件和地下微生物群落结构。我们显示，牧场土壤中排放的CH ₄含量较高（平均值：3454.6±9482.3μgCH ₄ m ^-2 d ^-1），与先前的报告一致，而森林土壤中的CH ₄排放量平均较低（平均值：9.8±120.5）微克CH₄ m ^-2 d ^-1），但通常充当CH ₄汇。我们报告说，次生森林土壤倾向于消耗CH ₄（平均：-10.2±35.7μgCH ₄ m ^-2 d ^-1），表明牧场CH _4的排放可以逆转。我们应用一种新颖的计算方法来确定与通量无关的微生物群落属性，而与土壤化学性质无关。尽管已知这揭示了直接产生或消耗CH _4的分类单元（即分别为产甲烷菌和甲烷营养菌），但尚不清楚绝大多数已鉴定的分类单元会循环CH _4。。每种土地利用类型都有一个与CH ₄通量相关的分类单元的唯一子集，这表明土地利用的变化通过微生物群落组成的变化改变了CH _4的循环。两者合计，我们表明微生物的组成对于理解观察到的CH ₄动力学至关重要，并且微生物提供了环境变量无法捕获的解释力。