Microbial Biomass Is More Important than Runoff Export in Predicting Soil Inorganic Nitrogen Concentrations Following Forest Conversion in Subtropical China

Land

Minhuang Wang¹  Jr-Chuan Huang²  Teng-Chiu Lin³  Liuming Yang⁴  Yusheng Yang⁴  Shidong Chen⁴  Chao Xu⁴  Zhijie Yang⁴  Xiaofei Liu⁴  Decheng Xiong⁴ 

[1] Department of Ecology, School of Life Sciences, State Key Laboratory of Biocontrol, Sun Yat-Sen University, Guangzhou 510275, China;Department of Geography, National Taiwan University, Taipei 10617, Taiwan;Department of Life Science, National Taiwan Normal University, Taipei 11677, Taiwan;Fujian Provincial Key Laboratory for Plant Eco-Physiology, Fujian Normal University, Fuzhou 350007, China;

关键词: assisted natural regeneration;    fine root biomass;    forest conversion;    microbial biomass;    soil inorganic nitrogen;    surface runoff;   

DOI  :  10.3390/land11020295

来源: DOAJ

【 摘 要 】

Elevated runoff export and declines in soil microbial biomass and enzyme activity following forest conversion are known to reduce soil inorganic nitrogen (N) but their relative importance remains poorly understood. To explore their relative importance, we examined soil inorganic N (NH₄⁺ and NO₃⁻) concentrations in relation to microbial biomass, enzyme activity, and runoff export of inorganic N in a mature secondary forest, young (five years old) Castanopsis carlessi and Cunninghamia lanceolate (Chinese fir) plantations, and forests developing through assisted natural regeneration (ANR). The surface runoff export of inorganic N was greater, but fine root biomass, soil microbial biomass, enzyme activity, and inorganic N concentrations were smaller in the young plantations than the secondary forest and the young ANR forests. Microbial biomass, enzyme activity, and runoff inorganic N export explained 84% and 82% of the variation of soil NH₄⁺ and NO₃⁻ concentrations, respectively. Soil microbial biomass contributed 61% and 94% of the explaining power for the variation of soil NH₄⁺ and NO₃⁻ concentrations, respectively, among the forests. Positive relationships between microbial enzyme activity and soil inorganic N concentrations were likely mediated via microbial biomass as it was highly correlated with microbial enzyme activity. Although surface runoff export can reduce soil inorganic N, the effect attenuated a few years after forest conversion. By contrast, the differences in microbial biomass persisted for a long time, leading to its dominance in regulating soil inorganic N concentrations. Our results highlight that most of the variation in soil inorganic N concentration following forest conversion was related to soil microbial biomass and that assisted natural regeneration can effectively conserve soil N.

【 授权许可】

Unknown