Effects of Different Vegetation Restoration Types on Extracellular Enzymes and Stoichiometric Characteristics of Soil in Lu-shi Expressway Slopes, Sichuan Province

  Objective  The physical and chemical properties, extracellular enzyme activities and stoichiometric ratio of soil in slope of different vegetation restoration types and the main factors driving the changes of soil enzyme activities were studied, in order to provide scientific basis and reference for slope vegetation restoration engineering.

  Method  Taking the bare land (BL), restored grassland (RG), restored woodland (RW) and natural grassland (NG) of Lu-shi expressway slope as the research objects, soil moisture content, pH, and C-, N- and P-acquiring enzymes in soil were measured.

  Result  ① The results showed that soil physical and chemical properties were significantly affected by vegetation restoration types. Soil moisture content was the highest in natural grassland and restored woodland and the lowest was in bare land, while soil nitrogen content was the highest in natural grassland and restored grassland and the lowest was in bare land. ②The activities of cellobiose hydrolase, β-glucosidase, 1, 4-β-N-acetylglucosaminidase and acid phosphatase in bare soil were lower than those of the other three vegetation types. ③ Except for vector length (VL), soil enzyme stoichiometric ratios of different vegetation restoration types were significantly different, and the vector angles were all greater than 45°, indicating that soil microorganisms of the four vegetation restoration types were more susceptible to phosphorus restriction.④ Redundancy analysis showed that five environmental factors, including soil C/N, moisture content, pH, total C content and soil N content, accounted for 84.7% of the variation of soil enzyme activities and stoichiometric ratios. Soil C/N and moisture content accounted for 52.4% and 39.2% of the variation, respectively.

  Conclusion  Different vegetation restoration types can significantly affect soil physicochemical properties, extracellular enzyme activities and its stoichiometric ratio. Soil C/N and water content have major regulatory effects on soil extracellular enzyme activities and enzyme stoichiometric ratio. In this study area, soil microbial growth and activity are mainly limited by phosphorus. On the whole, natural grassland and restored grassland were superior to the other two vegetation types.