Proximate controls on semiarid soil greenhouse gas fluxes across 3 million years of soil development

Soils are important sources and sinks of three greenhouse gases (GHGs): carbon dioxide (CO2), methane (CH4), and nitrous oxide (N2O). However, it is unknown whether semiarid landscapes are important contributors to global fluxes of these gases, partly because our mechanistic understanding of soil GHG fluxes is largely derived from more humid ecosystems. We designed this study with the objective of identifying the important soil physical and biogeochemical controls on soil GHG fluxes in semiarid soils by observing seasonal changes in soil GHG fluxes across a three million year substrate age gradient in northern Arizona. We also manipulated soil nitrogen (N) and phosphorus availability with 7 years of fertilization and used regression tree analysis to identify drivers of unfertilized and fertilized soil GHG fluxes. Similar to humid ecosystems, soil N2O flux was correlated with changes in N and water availability and soil CO2 efflux was correlated with changes in water availability and tem...

土壤是二氧化碳（CO₂）、甲烷（CH₄）和氧化亚氮（N₂O）这三种温室气体（GHGs）的重要源与汇。然而，目前尚不清楚半干旱景观是否为这些温室气体的全球通量做出了重要贡献，部分原因在于我们对土壤温室气体通量的机制性认知，主要源自湿润生态系统的相关研究。本研究旨在明确半干旱土壤中调控土壤温室气体通量的关键土壤物理与生物地球化学因子，具体通过监测亚利桑那州北部一条横跨300万年基质年龄梯度样带的土壤温室气体通量季节变化来实现。本研究还通过为期7年的施肥实验调控土壤氮（N）、磷（P）有效性，并采用回归树分析方法，分别识别未施肥与施肥土壤温室气体通量的驱动因子。与湿润生态系统类似，土壤氧化亚氮通量与氮、水分有效性的变化呈显著相关，而土壤二氧化碳排放通量则与水分有效性及温...