Differential mechanisms drive changes in soil C pools under N and P enrichment in a subalpine spruce plantation

• DOI: 10.1016/j.geoderma.2019.01.027
• Publication Date: 2019-01-15T05:14:44Z
• Authors: Junsheng Huang; Lingli Liu; Kaibin Qi; Tinghui Yang; Bing Yang; Weikai Bao; Xueyong Pang
• Keywords: Cycling; Soil carbon; Subalpine forest

Abstract Nitrogen (N) and phosphorus (P) availabilities can affect soil C cycling by altering both plants and microbial activity. It remains unclear how the changes in plant and microbial processes could regulate C dynamics of different soil fractions, thereby affecting soil C sequestration. Based on a field fertilization experiment in a subalpine spruce plantation, we examined the effects of N, P and combined N and P addition (NP) treatments on plant C inputs, soil C contents and enzyme activities of bulk soil and different aggregate fractions. We aimed to explore the mechanisms by which N and P addition affected soil C sequestration. After 4-year fertilization, the N treatment increased soil C content by 21%, accompanied by suppressed polyphenol oxidase activity (−43%). However, the P and NP treatments decreased soil C content by 14% and 7%, respectively, accompanied by reduction in fine root biomass (−51% and −50%, respectively). Fertilization also affected soil aggregate C pools, with decreased C content in the macroaggregates (5000–250 μm; MaA) under the P and NP treatments, and increased C content in the silt and clay fraction (