Elsevier

Soil Biology and Biochemistry

Volume 57, February 2013, Pages 204-211
Soil Biology and Biochemistry

Soil pH drives the spatial distribution of bacterial communities along elevation on Changbai Mountain

https://doi.org/10.1016/j.soilbio.2012.07.013Get rights and content

Abstract

The elevational patterns of diversity for plants and animals have been well established over the past century. However, it is unclear whether there is a general elevational distribution pattern for microbes. Changbai Mountain is one of few well conserved natural ecosystems, where the vertical distribution of vegetation is known to mirror the vegetation horizontal zonation from temperate to frigid zones on the Eurasian continent. Here, we present a comprehensive analysis of soil bacterial community composition and diversity along six elevations representing six typical vegetation types from forest to alpine tundra using a bar-coded pyrosequencing technique. The bacterial communities differed dramatically along elevations (vegetation types), and the community composition was significantly correlated with soil pH, carbon/nitrogen ratio (C/N), moisture or total organic carbon (TOC), respectively. Phylogenetic diversity was positively correlated with soil pH (P = 0.024), while phylotype richness was positively correlated with soil pH (P = 0.004), total nitrogen (TN) (P = 0.030), and negatively correlated with C/N ratio (P = 0.021). Our results emphasize that pH is a better predictor of soil bacterial elevational distribution and also suggest that vegetation types may indirectly affect soil bacterial elevational distribution through altering soil C and N status.

Highlights

► We examine soil bacterial distribution along elevation. ► Bacterial communities differed dramatically along elevation. ► Bacterial diversity and community composition were correlated with soil pH. ► Soil pH is a better predictor of bacterial elevational distribution.

Introduction

Improved knowledge of biological elevational diversity patterns is indispensable to a comprehensive understanding the influences of climate change on ecosystems (Lomolino, 2001; Rahbek, 2005; Grytnes and McCain, 2007; Malhi et al., 2010). Intensive and extensive studies have showed that taxa of macroorganisms, such as trees, mammals, birds, insects, generally exhibit either monotonically decreasing or hump-shaped richness patterns with elevation driven by potential forces, including climatic, spatial, historical and biotic (Herzog et al., 2005; McCain, 2005, 2009; Rahbek, 2005; Cardelus et al., 2006; Lomolino, 2001; Grytnes and McCain, 2007). Climatic factors in particular showed the strongest positive associations with biological elevational diversity patterns (Hawkins et al., 2003; Currie et al., 2004; Storch et al., 2006; Forister et al., 2010). Compared with macrooganisms, we know very little about the pattern of microbial diversity across elevational gradients, though microbes drive many important biogeochemical cycles on earth.

Though encouraging progress has been made on horizontal distribution of microbial communities recently (Rousk et al., 2010; Hollister et al., 2010; Fierer and Jackson, 2006; Lauber et al., 2009; Chu et al., 2010; Griffiths et al., 2011), only few investigations about their elevational diversity patterns are reported. Bryant et al. (2008) pointed out that Acidobacteria diversity decreased monotonically with elevation, which was driven by soil pH changes, while Wang et al. (2011) observed the inverse bacterial elevational pattern influenced by carbon supply in a stony stream located on Laojun Mountain. These contradictory results have led to more confusions than elucidations. Thus, more studies of the changing microbial patterns along elevational gradients are needed for a better understanding of underlying mechanism (Fierer et al., 2011).

The Changbai Mountain is the highest mountain in north-eastern China and is the head of three large rivers (the Songhua, Yalu and Tumen) (He et al., 2005). The vertical distribution of vegetation is known to mirror the vegetation horizontal zonation from temperate to frigid zones on the Eurasian continent (Xu et al., 2004; Zhang et al., 2011). In particular, a typical alpine tundra belt was above 2000 m where the majority of plants are of polar origin from the Quaternary period glacier retreat (Xu et al., 2004), and these soils may be expected to harbor relatively unique bacterial communities. Meanwhile, Changbai Mountain is one of few well conserved natural ecosystems on the earth (He et al., 2005). All the aforementioned provide an optimal environment to investigate microbial elevational patterns. The objectives of this study were (1) to explore the elevational diversity gradient of bacterial communities on Changbai Mountain, (2) to determine key factors controlling the distribution of bacterial communities, (3) and to compare the differences of bacterial communities in tundra and forest ecosystems.

Section snippets

Site selection and soil sampling

Changbai Mountain (126°55′–129°00′E; 41°23′–42°36′N) is located in Jilin Province, of northeast China, which extends along the border of China and North Korea. It is the highest mountain in north-eastern China and is the head of three large rivers (the Songhua, Yalu and Tumen). Topographic features differ on the four slopes of the mountain, with the northern slope being relatively moderate (average slope <3%) and other slopes being relatively steep (average slope 10%). The climate is a typical

Bacterial community composition

Across all soil samples, we obtained 148,788 quality sequences in total with 4037–8104 sequences per sample (mean 6200), and were able to classify 86.6% of those sequences. The dominant phyla across all the Changbai Mountain soils were Acidobacteria, Alphaproteobacteria, Actinobacteria, Betaproteobacteria and Gammaproteobacteria, accounting for more than 75% of the bacterial sequences from each of the soils (Fig. 1). In addition, Bacteroidetes, Gemmatimonadetes, Deltaproteobacteria,

Discussion

The elevational diversity gradient is one of the most fundamental patterns in animal and plant biogeography. Here we observed that soil bacterial diversity exhibit no apparent elevational gradient on Changbai Mountain, neither monotonous nor unimodal within macroorganisms (Herzog et al., 2005; McCain, 2005, 2009; Rahbek, 2005; Cardelus et al., 2006), which is in agreement with the results of Zhang et al. (2009) and Fierer et al. (2011). These results suggest that bacterial distribution may not

Acknowledgments

We thank Shijie Han and Guanhua Dai for assistance with soil sampling, Juan Liu for lab assistance and Lei Wang from Nankai University for assistance in pyrosequencing. We also thank Noah Fierer and Rob Knight from the University of Colorado for providing bioinformatic pipelines and useful discussions on microbial biogeography. This study was conducted at the Research Station of Changbai Mountain Forest Ecosystems, Chinese Academy of Sciences. This work was supported by the National Natural

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