# Spatial Distribution of Soil Bacterial Communities Along an Altitudinal Gradient in Alpine Meadows of the Northeastern Qinghai–Tibet Plateau and Their Relationship with Environmental Factors

## TL;DR

This study explores how soil bacteria in alpine meadows change with elevation and how they relate to soil nutrients and enzyme activity.

## Contribution

The study reveals elevation-driven shifts in soil bacterial communities and their strong links to soil nutrients and enzyme activity in alpine ecosystems.

## Key findings

- Bacterial diversity increases with elevation, peaking at 4500 m.
- Soil bacterial communities are strongly correlated with total potassium, available phosphorus, catalase, and urease.
- Elevation is the primary factor driving bacterial community variation in alpine meadows.

## Abstract

Alpine meadows rely on soil bacteria that recycle plant nutrients and help maintain soil health. The study area experiences a cold and dry climate, situated on the northeastern edge of the Qinghai-Tibet Plateau. The mean annual temperature varies between −3 and 2 °C, accompanied by a brief growing season. Although soil development is slow, the accumulation of organic matter is pronounced. However, it is not well understood how these bacteria change with altitude. To investigate how environmental conditions shape microbial communities in high-mountain ecosystems, soil samples were collected from alpine meadows along an elevational gradient on the northeastern Qinghai–Tibet Plateau. The aim was to assess shifts in soil bacterial community composition with altitude and to explore how these shifts relate to soil nutrient status and enzyme activity. The results showed that both the types and diversity of soil bacteria varied across elevations, with higher elevations generally having greater bacterial diversity. Differences in bacterial communities were closely linked to soil nutrients and enzyme activity. These findings help improve our understanding of how soil life responds to environmental changes in alpine ecosystems and provide useful information for managing and protecting these sensitive environments in the future.

Despite the essential role of soil microbial communities in driving nutrient cycling within alpine meadows, their distribution patterns along elevational gradients and their responses to environmental changes remain largely unexplored. To investigate this, soil samples were collected from five elevations (3300–4500 m) in the northeastern Qinghai–Tibet Plateau to analyze bacterial community composition and diversity, as well as their associations with soil physicochemical properties and enzyme activities. The results showed significant variation in bacterial community composition and diversity across elevations. Actinomycetota, Pseudomonadota, and Acidobacteriota were the dominant phyla at all sampling sites. Community diversity, measured by the Shannon index, generally increased with elevation, peaking at 4500 m and lowest at 3300 m. Pearson correlation analysis and redundancy analysis (RDA) indicated that soil bacterial community structure was significantly correlated with both soil nutrient factors and enzyme activities. Among these variables, total potassium, available phosphorus, catalase, and urease were strongly correlated with bacterial community differentiation. In addition, PERMANOVA results showed that elevation was the primary factor driving community variation, explaining a substantial proportion of the variation in community composition at a statistically significant level. Overall, this study highlights the distribution of bacterial communities in alpine meadow soils along an elevational gradient and their environmental associations, providing foundational data for understanding microbial community responses to environmental changes in alpine ecosystems.