Extracellular enzyme activity and stoichiometric characteristics of biological crust in mycorrhizal restoration area of western coal mining subsidence

Abstract

Arbuscular Mycorrhizal Fungi (AMF) can promote ecological restoration in coal mining areas for a long time, and can directly affect the growth and development of biological crusts, but the effects of biological crusts on nutrient cycling and extracellular enzyme activities are rarely reported.The control (CK) zone and AMF zone of Daliuta coal mining subsidence microbial reclamation demonstration base for 11 years were used as the study zones. Four different types of biological crust in two zones: algal crust, mixed algal crust (algal coverage > 50%), mixed moss crust (moss coverage > 50%), and moss crust were taken as the research objects. The coverage and thickness of different types of biological crust, total organic carbon (TOC), total nitrogen (TN), total phosphorus (TP) of soil, litter, and understory vegetation, and the activities of β–1, 4–glucosylase (BG), β–1, 4–acetyl glucosylase (NAG), leucine aminopeptidase (LAP) and alkaline phosphatase (AP) were taken as the analysis contents. The coverage of algae crust in CK zone was 31.3% higher than that of moss crust，and the coverage of moss crust in AMF zone was 27% higher than that of algae crust. The thickness of biological crust in AMF zone and CK zone showed the trend of algae crust < mixed algae crust < mixed moss crust < moss crust. The thickness of biological crust in AMF zone was greater than that in CK zone. It shows that mycorrhizal reclamation promotes the development of biological crust in coal mining subsidence area in western China.The soil organic carbon (SOC), TN, TP and the activities of extracellular enzymes BG, NAG+LAP and AP were significantly higher than those in bare soil,and the moss crust was significantly higher than that of algae crust. It shows that the succession of biological crust accelerates the recovery and circulation of nutrients in the surface soil. The SOC and TN contents and the activities of extracellular enzymes BG, NAG+LAP and AP in AMF zone were significantly higher than those in CK zone. The microbial community in crusted soil was limited by P. The biological crust showed a gradual increase trend of C/P and N/P from algae crust to moss crust, but ABG/(ANAG+ALAP) and ABG/AAP decreased with the development of crust from algae crust to moss crust. RDA analysis showed that SOC, TN, TP were positively correlated with the activities of BG, NAG+LAP and AP, but negatively correlated with the length and Angle of the enzyme vector. AMF can improve the nutrient content and extracellular enzyme activity of biological crust, alleviate phosphorus limitation by improving litter coverage, herb vegetation coverage and nutrient status under forest.

Keywords

• soil extracellular enzymes
• biological crust
• arbuscular mycorrhizal fungi
• stoichiometric characteristics
• nutrient limitation