Seasonal changes in soil properties, microbial biomass and enzyme activities across the soil profile in two alpine ecosystems

Highlights

• We measured soil variables along the profile in two alpine ecosystems.

• Most of soil properties decreased with depth and varied with time.

• Root and microbial biomass decreased with depth and increased with time.

• Soil enzyme activities decreased with depth but showed little change with time.

• Soil properties and microbial biomass were more dynamic than enzyme activities.

Abstract

Microbial biomass and extracellular enzyme activities control the rate of soil organic carbon decomposition, thereby affecting soil carbon pool. However, seasonal dynamics of soil microbial properties at different depths of the soil profile remain unclear. In this study, we sampled soils in the early, middle and late growing season at different soil depths (0–100 cm) in two alpine ecosystems (meadow and shrubland) on the Tibetan Plateau. We measured plant belowground biomass, soil properties, microbial biomass and extracellular enzyme activities. We found that soil properties changed significantly with sampling time and soil depth. Specifically, most of soil properties consistently decreased with increasing soil depth, but inconsistently varied with sampling time. Moreover, root biomass and microbial biomass decreased with increasing soil depth and increased with sampling time during the growing season. However, microbial extracellular enzyme activities and their vector properties all changed with depth, but did not vary significantly with time. Taken together, these results show that soil properties, microbial biomass and extracellular enzyme activities mostly decline with increasing depth of the soil profile, and soil properties and microbial biomass are generally more variable during the growing season than extracellular enzyme activities across the soil profile in these alpine ecosystems. Further studies are needed to investigate the changes in soil microbial community composition and function at different soil depths over the growing season, which can enhance our mechanistic understanding of whole-profile soil carbon dynamics of alpine ecosystems under climate change.

Graphical abstract

Keywords

Seasonal variation / Soil depth / Microbial biomass / Extracellular enzyme activity / Alpine ecosystem

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Acknowledgments

We thank the staff at the Haibei station of Chinese Academy of Sciences for providing climate data and logistic support in the field. This study was financially supported by the National Natural Science Foundation of China (31971528 and 31988102). We also appreciate the constructive comments and suggestions from two anonymous reviewers that greatly improved this work.

Electronic supplementary material

Supplementary material is available in the online version of this article at https://doi.org/10.1007/s42832-021-0101-7 and is accessible for authorized users.

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