Arid Zone Research ›› 2022, Vol. 39 ›› Issue (2): 456-468.doi: 10.13866/j.azr.2022.02.13

• Soil Resources • Previous Articles     Next Articles

Variation in soil extracellular enzyme activities stoichiometry during biological soil crust formation in the Loess Plateau

YAO Hongjia1(),WANG Baorong2,3,AN Shaoshan1,2,YANG E’nv1,HUANG Yimei4   

  1. 1. State Key Laboratory of Soil Erosion and Dryland Farming on the Loess Plateau, Institute of Soil and Water Conservation, Northwest A & F University, Yangling 712100, Shaanxi, China
    2. State Key Laboratory of Soil Erosion and Dryland Farming on the Loess Plateau, Institute of Soil and Water Conservation, Chinese Academy of Science and Ministry of Water Resources, Yangling 712100, Shaanxi, China
    3. University of Chinese Academy of Sciences, Beijing 100049, China
    4. Key Laboratory of Plant Nutrition and the Agro-Environment in Northwest China, Ministry of Agriculture, College of Natural Resources and Environment, Northwest A & F University, Yangling 712100, Shaanxi, China
  • Received:2021-08-24 Revised:2021-11-24 Online:2022-03-15 Published:2022-03-30

Abstract:

Biological soil crusts (BSCs) play an important role in enhancing soil resistance to water and wind erosion, and improving soil nutrients. Soil extracellular enzyme activity can be used as a microbial indicator of the intensity of soil biochemical reactions, which is important for understanding the nutrient cycling processes involving microorganisms in desert ecosystems. However, there is a lack of understanding of the variation in soil extracellular enzymes and their stoichiometry during the formation of BSCs on the Loess Plateau. Soils from five biological crust formation stages (CK, A, AM, MA, and M) in Liudaogou watershed, Shenmu County, on the Loess Plateau were selected for the study. Soil extracellular enzyme activities [β-1,4-glucosidase (BG), β-1,4-N-acetylaminoglucosidase (NAG), leucine aminopeptidase (LAP), and alkaline phosphatase (AP)] and their stoichiometric changes during the formation of biocrusts were characterized. The activities of soil BG, NAG, LAP, and AP increased significantly with the sequence of biological crust development, and activity was significantly greater in Mo soil than that in Al soil (P<0.05). Extracellular enzyme activities were significantly higher in the BSCs layer than those in the lower soil layer, and decreased continuously with the depth of the soil. Soil C, N, P, C:P, and N:P all showed highly significant positive correlations with soil extracellular enzyme activities (P<0.05). The nutrient content and soil extracellular enzyme activity of soil with crust cover were significantly higher than those of bare land, and those of Mo soil were significantly higher than those of Al soil. Standardized major axis estimates indicated that soil extracellular enzyme activities were significantly enhanced and showed homeostasis with formation of biological crusts, and the slopes between N- and P-acquiring enzymes relative to C-acquiring enzymes showed isotropic relationships. Soil microorganisms play an important role in nutrient cycling in arid and semi-arid ecosystems through homeostatic regulation of extracellular enzyme stoichiometry.

Key words: biological soil crusts, developmental sequence, extracellular enzymes, stoichiometry, Loess Plateau