Abstract：
The amount of nitrogen stored in terrestrial soils, its \"nitrogen pool\", moderates biogeochemical cycling affecting primary productivity, nitrogen pollution and even carbon budgets. The soil nitrogen pools and the transformation of nitrogen forms within them are heavily influenced by environmental factors including anthropogenic activities. However, our understanding of the global distribution of soil nitrogen with respect to anthropogenic activity and human land use remains unclear. We constructed a meta-analysis from a global sampling, in which we compare soil total nitrogen pools and the driving mechanisms affecting each pool across three major classifications of human land use: natural, agricultural, and urban. Although the size of the nitrogen pool can be similar across natural, agricultural and urban soils, the ecological and human associated drivers vary. Specifically, the drivers within agricultural and urban soils as opposed to natural soils are more complex and often decoupled from climatic and soil factors. This suggests that the nitrogen pools of those soils may be co-moderated by other factors not included in our analyses, like human activities. Our analysis supports the notion that agricultural soils act as a nitrogen source while urban soils as a nitrogen sink and informs a modern understanding of the fates and distributions of anthropogenic nitrogen in natural, agricultural, and urban soils.
摘要：
陆地土壤中储存的氮量，其“氮池”，缓和影响初级生产力的生物地球化学循环，氮污染甚至碳预算。土壤氮库及其内部氮素形式的转化受到包括人为活动在内的环境因素的严重影响。然而,我们对人为活动和人类土地利用方面土壤氮的全球分布的理解仍不清楚。我们从全球抽样中构建了一个荟萃分析，在其中，我们比较了土壤总氮库以及影响人类土地利用的三个主要分类中每个池的驱动机制：自然，农业,和城市。虽然氮池的大小可以在整个自然相似，农业和城市土壤，生态和人类相关的驱动因素各不相同。具体来说,与自然土壤相比，农业和城市土壤中的驱动因素更为复杂，并且通常与气候和土壤因素脱钩。这表明这些土壤的氮库可能受到我们分析中未包括的其他因素的共同调节，就像人类活动一样。我们的分析支持农业土壤作为氮源，而城市土壤作为氮汇的概念，并告知人们对自然人为氮的命运和分布的现代理解，农业,城市土壤。
