The Biogeography of Forest Soil Microbial Functional Diversity Responds to Forest Types across Guangxi, Southwest China

Wanxia Peng,Kelin Wang,Fuping Zeng,Hu Du,Tongqing Song,Zhaoxia Zeng,Hao Zhang,Feng Wang,Qiujin Tan

doi:10.3390/f12111578

Abstract

Vegetation and soil have spatial distributions at different scales, while the spatial distribution of soil microorganisms and factors driving their distribution are still unclear. We aimed to reveal the spatial pattern of microbial functional diversity and to identify its drivers in forest soils at a regional scale. Here, we performed an investigation of microbes across several forest types covering an area of 236,700 km2 in Guangxi, southwest China. We examined a total of 185 samples for soil microbial functional diversity using Biolog EcoPlates. The soil microbial functional diversity had strong spatial heterogeneity across the Guangxi region. The distribution of microorganisms in forest soils was mainly determined by total nitrogen, available N, and C:N ratio, and stand age. We found that coniferous forests, especially pine forest, exhibited lower functional diversity, but the reverse was true for deciduous broadleaf forest/mixed evergreen and deciduous broadleaf forest. Our findings suggested that a heterogeneous distribution of microbial functional diversity in forest soils is related to forest types in Guangxi, China. In conclusion, high soil microbial functional diversity is favored in subtropical forests with looser soil structure, lower soil C:N ratio, greater total soil nitrogen and available nitrogen concentration, and broad-leaved tree species.

Highlights

Soil microbes play an essential role in driving and regulating global cycling of biogeochemical nutrients, and the interactions among these nutrients have important feedbacks to Earth’s landscapes, climate, and ecosystems [1,2,3]
The results indicated that soil total nitrogen, available nitrogen, soil organic carbon, and average stand age were most correlated with the first component, average stand DBH for the second component, and mean annual precipitation for the third component (Figure 3b)
The demonstration that soil functional diversity did not follow a normal or lognormal distribution implied that its distribution between Guangxi forest soils (Table S1) was nonstochastic, and that functional diversity could be under the dependence of environmental conditions

Summary

Introduction

Soil microbes play an essential role in driving and regulating global cycling of biogeochemical nutrients (carbon, C; nitrogen, N; phosphorus, P), and the interactions among these nutrients have important feedbacks to Earth’s landscapes, climate, and ecosystems [1,2,3]. Many researchers have interpreted the spatial heterogeneity of soil nutrient interactions among climate, vegetation, and land uses [3,4]. At the national and continental scales, it has been found that soil pH dominates soil bacterial diversity [9,10], while soil texture, pH, total organic carbon, and land use has been shown to control soil molecular microbial biomass [11]. Temperature affects ammonia-oxidizing bacteria [14], microbial biomass, and community profiles [15], and dispersal limitation and habitat heterogeneity affect soil microbial taxa [16] and microbial diversity [17], respectively. The differences in the spatial patterns of vegetation, soil, and soil microorganisms are well understood, while how microbes feedback to the distribution of the vegetation–soil system remains unclear

Objectives

Methods

Results

Discussion

Conclusion