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Background and aims <p>The alpine meadows of the Qinghai-Tibet Plateau are experiencing shrub expansion, which may lead to ecosystem degradation and functional homogenization. Although previous studies have examined the mechanisms driving shrub expansion, as well as plant diversity and soil properties, the effect on soil microbial communities remain poorly understood.</p> Methods <p>In this two-year field study conducted in Hongyuan County, Sichuan, we employed a paired design to compare shrub patches (SP) with meadow patches (MP).</p> Results <p>Our findings revealed that SP exhibited significantly higher soil electrical conductivity (EC, + 20.00%), soil organic matter (SOM, + 16.53%), and total nitrogen (TN, + 22.26%), but lower soil water content (SWC, –12.24%). Notably, enzyme activities showed marked reductions in SP, with alkaline phosphatase (APA), sucrase (SA), and catalase (CAT) decreasing by 15.92%, 33.62%, and 10.46%, respectively. Microbial biomass carbon and nitrogen also diminished by 21.06% and 16.67%. Although <i>Proteobacteria</i>, <i>Acidobacteriota</i>, <i>Verrucomicrobiota</i>, and <i>Bacteroidota</i> dominated both patch types, shrub patches exhibited higher species richness (Chao1) but similar Shannon and Simpson diversity indices. Redundancy analysis identified sucrase activity as key driver of bacterial community composition.</p> Conclusion <p>We propose that shrub expansion functions as an ecosystem driver by restructuring the soil bacterial community through the suppression of enzyme activity and the reduction of microbial biomass, thereby altering the system's functional potential.</p>

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Soil enzymatic activities and microbial biomass drive bacterial community responses to shrub expansion in an alpine meadow

  • 期刊论文

  • 发表日期：

    2026年5月3日

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  • Jingru Chen,
  • Zelong Zhang,
  • Lei Ma,
  • Lili Nan

摘要

Background and aims

The alpine meadows of the Qinghai-Tibet Plateau are experiencing shrub expansion, which may lead to ecosystem degradation and functional homogenization. Although previous studies have examined the mechanisms driving shrub expansion, as well as plant diversity and soil properties, the effect on soil microbial communities remain poorly understood.

Methods

In this two-year field study conducted in Hongyuan County, Sichuan, we employed a paired design to compare shrub patches (SP) with meadow patches (MP).

Results

Our findings revealed that SP exhibited significantly higher soil electrical conductivity (EC, + 20.00%), soil organic matter (SOM, + 16.53%), and total nitrogen (TN, + 22.26%), but lower soil water content (SWC, –12.24%). Notably, enzyme activities showed marked reductions in SP, with alkaline phosphatase (APA), sucrase (SA), and catalase (CAT) decreasing by 15.92%, 33.62%, and 10.46%, respectively. Microbial biomass carbon and nitrogen also diminished by 21.06% and 16.67%. Although Proteobacteria, Acidobacteriota, Verrucomicrobiota, and Bacteroidota dominated both patch types, shrub patches exhibited higher species richness (Chao1) but similar Shannon and Simpson diversity indices. Redundancy analysis identified sucrase activity as key driver of bacterial community composition.

Conclusion

We propose that shrub expansion functions as an ecosystem driver by restructuring the soil bacterial community through the suppression of enzyme activity and the reduction of microbial biomass, thereby altering the system's functional potential.