Soil enzyme kinetics and thermodynamics in response to long-term vegetation succession

ZiWen Zhao; Yang Wu; WenJing Chen; Wei Sun; ZhanHui Wang; GuoBin Liu; Sha Xue

doi:10.1016/j.scitotenv.2023.163542

Soil enzyme kinetics and thermodynamics in response to long-term vegetation succession

Sci Total Environ. 2023 Jul 15:882:163542. doi: 10.1016/j.scitotenv.2023.163542. Epub 2023 Apr 17.

Authors

ZiWen Zhao¹, Yang Wu¹, WenJing Chen¹, Wei Sun¹, ZhanHui Wang², GuoBin Liu³, Sha Xue⁴

Affiliations

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, China; College of Forestry, Northwest A&F University, Yangling 712100, China.
² Hebei Drinking Water Safety Monitoring Technology Innovation Center, Chengde 067000, China.
³ 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, China; Institute of Soil and Water Conservation, Chinese Academy of Sciences and Ministry of Water Resources, Yangling 712100, China.
⁴ 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, China; Institute of Soil and Water Conservation, Chinese Academy of Sciences and Ministry of Water Resources, Yangling 712100, China. Electronic address: xuesha100@163.com.

PMID: 37076007
DOI: 10.1016/j.scitotenv.2023.163542

Abstract

Our current knowledge regarding soil organic matter (SOM) turnover during vegetation succession is often limited to conventional C decomposition models. However, microbial enzyme-mediated SOM degradation and nutrient cycling are mainly reflected in the kinetic parameters of these enzymes. Changes in the composition and structure of plant communities are typically accompanied by alterations in soil ecological functions. Therefore, it is important to clarify the kinetic parameters of soil enzymes and their temperature sensitivity in response to vegetation succession, especially under the current trend of climate change-related global warming; however, these are still understudied. Here, we examined the kinetic parameters of soil enzymes, their temperature sensitivity, and their associations with environmental variables over long-term (approximately 160 years) vegetation succession on the Loess Plateau using a space-for-time substitution method. We found that the kinetic parameters of soil enzymes changed significantly during vegetation succession. Specific response characteristics varied depending on the enzyme. Overall, the temperature sensitivity (Q₁₀, 0.79-1.87) and activation energy (E_a, 8.69-41.49 kJ·mol^-1) remained stable during long-term succession. Compared with N-acetyl-glucosaminidase and alkaline phosphatase, β-glucosidase was more sensitive to extreme temperatures. In particular, two kinetic parameters (i.e., maximum reaction rate, V_max; half-saturation constant, K_m) of β-glucosidase were decoupled at low (5 °C) and high (35 °C) temperatures. Overall, V_max was the primary determinant of variations of enzyme catalytic efficiency (K_cat) during succession, and soil total nutrients had a greater impact on K_cat than available nutrients. Our results suggested that soil ecosystems played an increasingly important role as a C source during long-term vegetation succession, as indicated by the positive responses of the C cycling enzyme K_cat, while the factors related to soil N and P cycling remained relatively stable.

Keywords: Carbon decomposition; Enzyme kinetics; Enzyme thermodynamics; Nutrient cycling; Vegetation succession.

MeSH terms

Carbon
Cellulases*
Ecosystem*
Kinetics
Soil / chemistry
Soil Microbiology
Thermodynamics

Substances

Soil
Cellulases
Carbon