Contrasting responses of soil microbial biomass and extracellular enzyme activity along an elevation gradient on the eastern Qinghai-Tibetan Plateau

Shun Liu; Gexi Xu; Huanhuan Chen; Miaomiao Zhang; Xiangwen Cao; Miao Chen; Jian Chen; Qiuhong Feng; Zuomin Shi

doi:10.3389/fmicb.2023.974316

Contrasting responses of soil microbial biomass and extracellular enzyme activity along an elevation gradient on the eastern Qinghai-Tibetan Plateau

Front Microbiol. 2023 Jan 18:14:974316. doi: 10.3389/fmicb.2023.974316. eCollection 2023.

Authors

Shun Liu^{1

2}, Gexi Xu^{1

2}, Huanhuan Chen^{1

2}, Miaomiao Zhang^{1

2}, Xiangwen Cao^{1

2}, Miao Chen^{1

2}, Jian Chen^{1

2}, Qiuhong Feng³, Zuomin Shi^{1

2

4

5}

Affiliations

¹ Key Laboratory of Forest Ecology and Environment of National Forestry and Grassland Administration, Ecology and Nature Conservation Institute, Chinese Academy of Forestry, Beijing, China.
² Miyaluo Research Station of Alpine Forest Ecosystem, Lixian County, China.
³ Ecological Restoration and Conservation on Forest and Wetland Key Laboratory of Sichuan Province, Sichuan Wolong Forest Ecosystem Research Station, Sichuan Academy of Forestry, Chengdu, China.
⁴ Co-Innovation Center for Sustainable Forestry in Southern China, Nanjing Forestry University, Nanjing, China.
⁵ Institute for Sustainable Plant Protection, National Research Council of Italy, Turino, Italy.

Abstract

Soil microbial community composition and extracellular enzyme activity are two main drivers of biogeochemical cycling. Knowledge about their elevational patterns is of great importance for predicting ecosystem functioning in response to climate change. Nevertheless, there is no consensus on how soil microbial community composition and extracellular enzyme activity vary with elevation, and little is known about their elevational variations on the eastern Qinghai-Tibetan Plateau, a region sensitive to global change. We therefore investigated the soil microbial community composition using phospholipid fatty acids (PLFAs) analysis, and enzyme activities at 2,820 m (coniferous and broadleaved mixed forest), 3,160 m (dark coniferous forest), 3,420 m (alpine dwarf forest), and 4,280 m (alpine shrubland) above sea level. Our results showed that soil microbial community composition and extracellular enzyme activities changed significantly along the elevational gradient. Biomass of total microbes, bacteria, and arbuscular mycorrhizal fungi at the highest elevation were the significantly lowest among the four elevations. In contrast, extracellular enzyme activities involved in carbon (C)-, nitrogen (N)-, and phosphorus (P)- acquiring exhibited the maximum values at the highest elevation. Total nutrients and available nutrients, especially P availability jointly explained the elevational pattern of soil microbial community, while the elevational variation of extracellular enzyme activities was dependent on total nutrients. Microbial metabolism was mainly C- and P-limited with an increasing C limitation but a decreasing P limitation along the elevational gradient, which was related significantly to mean annual temperature and total P. These results indicated a vital role of soil P in driving the elevational patterns of soil microbial community and metabolism. Overall, the study highlighted the contrasting responses of soil microbial biomass and extracellular enzyme activities to elevation, possibly suggesting the differences in adaption strategy between population growth and resource acquisition responding to elevation. The results provide essential information for understanding and predicting the response of belowground community and function to climate change on the eastern Qinghai-Tibetan Plateau.

Keywords: elevation; extracellular enzyme; microbial metabolism; phospholipid fatty acids; soil P; soil microbial community.