The patterns of soil nitrogen stocks and C : N stoichiometry under impervious surfaces in China

作者：Qian Ding, Hua Shao, Chi Zhang, Fang Xia · 发表于：Earth system science data · 年份：2023 · DOI：10.5194/essd-15-4599-2023 · 被引用次数：8 · 研究领域：Soil Carbon and Nitrogen Dynamics、Soil and Unsaturated Flow、Soil and Water Nutrient Dynamics

Abstract. Accurate assessment of soil nitrogen (N) storage and carbon (C) : N stoichiometry under impervious surface areas (ISAs) is key to understanding the impact of urbanization on soil health and the N cycle. Based on 888 soil profiles from 148 sampling sites in 41 cities across China, we estimated the country's N stock (100 cm depth) in the ISA soil to be 98.74±59.13 Tg N with a mean N density (NISA) of 0.59±0.35 kg m−2, which was significantly lower (at all depths) than the soil N density (NPSA=0.83±0.46 kg m−2) under the reference permeable surface areas (PSAs). The NISA was also only about 53 %–69 % of the reported national mean soil N density, indicating that ISA expansion caused soil N loss. The C:N ratio of ISA (10.33±2.62) was 26 %–34 % higher than that of natural ecosystems (forests, grasslands, etc.) but close to the C:N of PSA. Moreover, there was a significant C–N correlation in ISA soil, showing no signs of C–N decoupling as suggested by the previous studies. The ISA had smaller variances in the C:N ratio than did the PSA at regional scale, indicating convergence of soil C:N stoichiometry due to ISA conversion. The eastern subregion of China had the highest NISA, although its natural soil N density was among the lowest in the country. Unlike the vertical pattern in natural permeable soils, whose N density declined faster in the upper soil layers than in the lower layers, NISA decreased linearly with depth. Similarly to natural soil N, NISA was negatively corr...