Drivers of soil microbial metabolic limitation changes along a vegetation restoration gradient on the Loess Plateau, China

• Published in: Geoderma Vol. 353; pp. 188 - 200
• Main Authors: Deng, Lei, Peng, Changhui, Huang, Chunbo, Wang, Kaibo, Liu, Qiuyu, Liu, Yulin, Hai, Xuying, Shangguan, Zhouping
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 01.11.2019
• Subjects: alkaline phosphatase; China; chronosequences; ecological restoration; Enzymatic stoichiometry; enzyme activity; Farmland abandonment; Grassland; leucyl aminopeptidase; Microbial C limitation; microbial communities; Microbial P limitation; nutrients; Plant; Soil; soil enzymes; soil microorganisms; soil nutrients; soil water content; species diversity; stoichiometry; China; Grassland; Farmland abandonment; Plant; Microbial P limitation; Soil; Enzymatic stoichiometry; Microbial C limitation
• ISSN: 0016-7061; 1872-6259
• DOI: 10.1016/j.geoderma.2019.06.037

Soil extracellular enzymatic activity (EEA) stoichiometry could reflect the biogeochemical equilibrium between the metabolic requirements of microbial communities and environmental nutrients availability. However, the drivers of soil microbial metabolic limitation (SMML) changes remain poorly understood following vegetation restoration. We compared sites along a vegetation restoration chronosequence over a 30-year period on the Loess Plateau, China, and measured the potential activities of two C-acquiring enzymes (β-1,4-glucosidase (BG) and β-d-cellobiosidase (CBH)), two N-acquiring enzymes (β-1,4-N-acetylglucosaminidase (NAG) and l-leucine aminopeptidase (LAP)), and one organic-P-acquiring enzyme (alkaline phosphatase (AP)), to quantify and compare the variations in metabolic limitations for soil microorganisms using EEA stoichiometry. The results showed constant microbial P limitation, but not N limitation, and an open downward “unimodal” trend in microbial C limitation; however, the microbial P limitation displayed exactly the opposite trend during vegetation restoration. Restoration age and properties of plant, soil, and microorganisms contributed to 82.9% of microbial C limitation and 84.6% of microbial P limitation, with soil presenting the highest relative effects of 76.1% and 59.6% on microbial C and P limitations, respectively. Plant productivity and species diversity decreased microbial C limitation owing to increasing plant C inputs, but increased microbial P limitation owing to plant nutrients competition with soil microorganisms. When the fungi:bacteria ratio in the soil increased, the SMML increased. Vegetation restoration increased the soil nutrients content and reduced SMML, and a decrease in the soil water content increased microbial P limitation. Thus, the effects of long-term vegetation restoration on SMML were the result of combined influences of plants, soil, and microorganisms. •Soil microbes in abandoned farmland were limited by P rather than N on the Loess Plateau.•Vegetation restoration decreased microbial C limitation but increased P limitation.•Soil nutrient and microbial composition had a strong effect on microbial C and P limitation.•SOC and C/P are the two primary influences on C and P limitations.•Soil water had strong negative effect on microbial P limitation but no effect on C limitation.