Chin J Plant Ecol ›› 2022, Vol. 46 ›› Issue (2): 232-242.DOI: 10.17521/cjpe.2021.0215

Special Issue: 生态化学计量 青藏高原植物生态学:植物-土壤-微生物

• Research Articles • Previous Articles     Next Articles

Soil extracellular enzyme activities and their stoichiometric ratio in the alpine treeline ecotones in Gongga Mountain, China

LI Dong1,2, TIAN Qiu-Xiang2, ZHAO Xiao-Xiang2,3, LIN Qiao-Ling2,3, YUE Peng-Yun2,3, JIANG Qing-Hu2, LIU Feng2,*()   

  1. 1Research Center for Ecology and Environment of Qinghai-Tibetan Plateau, College of Science, Tibet University, Lhasa 850000, China
    2Key Laboratory of Aquatic Botany and Watershed Ecology, Wuhan Botanical Garden, Chinese Academic of Sciences, Wuhan 430074, China
    3University of Chinese Academic of Sciences, Beijing 100049, China
  • Received:2021-06-07 Accepted:2021-09-15 Online:2022-02-20 Published:2021-10-15
  • Contact: LIU Feng
  • Supported by:
    National Natural Science Foundation of China(31870465);National Natural Science Foundation of China(31700462)


Aims Soil extracellular enzymes and enzyme stoichiometry are indicators of soil nutrient availability and microbial substrate limitation. Subalpine treeline ecotones are special areas which are sensitive to global change. However, the patterns in soil enzyme activities and stoichiometry, and their key drivers remain unclear in the subalpine treeline ecotones.

Methods In this study, soils from a subalpine treeline ecotone in Gongga Mountain in Southeast of Qingzang Plateau were collected. The activities of five hydrolases (β-1,4-glucosidase (BG), cellobiohydrolase (CBH), xylosidase (XYL), β-N-acetyl glucosaminidase (NAG), leucine aminopeptidase (LAP)) and two oxidases (polyphenol oxidase (POX), catalase (CAT)) were detected. The stoichiometric ratios of soil extracellular enzyme activities (carbon and nitrogen enzyme activity ratio and carbon quality index) were calculated.

Important findings Our results showed that LAP, POX and CAT activities of the shrub soils were significantly lower than those of the treeline and forest soils, XYL activity was the lowest at the treeline, and the activities of other extracellular enzymes did not differ significantly among locations in the treeline ecotone. The lnBG/lnLAP of the shrub soil was significantly higher than those of the forest and treeline soils, lnBG/ln(NAG + LAP) did not vary significantly at the treeline ecotone, and the carbon quality index was highest at the treeline. Soil extracellular enzyme activity stoichiometric ratios were not significantly related to microbial nutrient status. Non-metric multidimensional scaling analysis showed that total carbon, total nitrogen, nitrate nitrogen content and lignin to nitrogen ratio of plant leaves were the main factors influencing soil extracellular enzyme activities in the treeline ecotone. The main drivers of the stoichiometric ratios of extracellular enzyme activities were soil dissolved nitrogen, carbon to nitrogen ratio, and lignin to nitrogen ratio of plant leaves. In summary, some soil enzyme activities and their stoichiometric ratios varied significantly along the treeline ecotone, which was mainly influenced by the changes in vegetation type, possibly via its influences on plant-associated microbial communities. Treeline migration induced by future climate change may change extracellular enzyme activities and thus affect soil nutrient cycling.

Key words: soil extracellular enzyme activities, treeline ecotones, enzyme stoichiometric ratio, vegetation type