Chin J Plant Ecol ›› 2022, Vol. 46 ›› Issue (7): 834-845.

• Research Articles •

### Characteristics of soil extracellular enzyme activities and their stoichiometry during rocky desertification in southwestern Guizhou, China

SUN Cai-Li1,2,*(), QIU Mo-Sheng1, HUANG Chao-Xiang1, WANG Yi-Wei1

1. 1College of Eco-Environmental Engineering, Guizhou Minzu University, Guiyang 550025, China
2The Karst Environmental Geological Hazard Prevention of Key Laboratory of State Ethnic Affairs Commission, Guizhou Minzu University, Guiyang 550025, China
• Received:2021-11-23 Accepted:2022-01-08 Online:2022-07-20 Published:2022-07-15
• Contact: SUN Cai-Li
• Supported by:
Guizhou Provincial Science and Technology Projects ([2020]1Y192);National Natural Science Foundation of China(41967058);Science and Technique Foundation of Education Department of Guizhou Province, China([2018]135)

Abstract:

Aims In this study, we sought to determine changes in soil extracellular enzyme activities and their stoichiometric characteristics during the process of karst rocky desertification and their ecological response to environmental variation.

Methods Soil ecosystems at five stages of rocky desertification were selected for investigation and we applied the theory and methods of ecological stoichiometry to systematically study the effects of rocky desertification on the activities of six extracellular enzymes (β-1,4-glucosidase, cellobiohydrolase, β-1,4-xylosidase, β-1,4-N- acetylglucosaminidase, leucine aminopeptidase, and acid phosphatase). We also analyzed correlations between enzyme activities and environmental factors.

Important findings The results revealed that the extracellular activities of β-1,4-glucosidase, cellobiohydrolase, β-1,4-xylosidase, and leucine aminopeptidase, in the no, potential, and slight stages of rocky desertification were significantly higher than those in the moderate and severe stages. In contrast, the stoichiometric characteristics of soil extracellular enzymes showed no significant differences among the different stages of rocky desertification. The quality of soil at the different stages of desertification could be roughly divided into three categories, namely, the biochemical properties of non-rocky desertification soil were superior to those at the potential and slight stages, which in turn were superior to those at the moderate and severe stages. In addition, soils at the no, potential, and slight stages of rocky desertification were found to be phosphorus deficient (the enzyme vector angle was greater than 45°), whereas soils at the moderate and severe stages were deficient in nitrogen (the enzyme vector angle was less than 45°). Moreover, we established that during the process of rocky desertification, the changes in soil extracellular enzyme activities and their stoichiometric characteristics were mainly influenced by soil total nitrogen, available phosphorus, nitrate nitrogen, ammonium nitrogen, and litter phosphorus contents. The observed changes in soil extracellular enzyme activities were found to be correlated with changes in nutrient contents, and tended to be limited by litter phosphorus content. On the basis of these findings, as measures to alleviate the associated nutrient limitations, we would recommend supplementation with phosphorus in the potential and slight stages of rocky desertification and the supplementary application of nitrogen in the moderate and severe stages during the restoration of rocky desert ecosystems.