Abstract
Soil microorganisms play a vital role in the biogeochemical cycle, whereas land use change is one of the primary factors that affects the biodiversity and functionality of terrestrial ecosystems. The composition and diversity of bacterial communities (by high-throughput sequencing of the bacterial 16S rRNA gene) were evaluated in the soils of the Montane Region of Northeast China, across different land use types, e.g., natural secondary forest (Quercus mongolica, QM), shrubland (SL), coniferous plantation (Larix gmelinii, LG, and Pinus koraiensis, PK), and agricultural land (Zea mays, ZM). Significant differences in the chemical characteristics and bacterial communities in soils under different land uses were observed in this study. Soil resident TC (total carbon) and TN (total nitrogen) were much higher in secondary natural forest soils, than in coniferous plantation and agricultural soils. Compared with forest and shrubland soils, soil bacterial OTUs, the Chao1 index, and the ACE index were the lowest in the ZM. There were high proportions of Proteobacteria, Actinobacteria, Acidobacteria, Chloroflexi, Gemmatimonadetes, Verrucomicrobia, Bacteroidetes, Planctomycetes, Saccharibacteria, and Nitrospirae in agricultural and forest soils, which accounted for over 90% of the reads in each sample. We found that the dominant group in the forest and shrubland soils was Proteobacteria, while the most dominant group in the ZM was Actinobacteria. The results of both heatmap and principal component analyses displayed groups according to land use types, which indicated that the bacterial communities in the areas under study were significantly influenced by long term differently managed land use. Furthermore, redundancy and Pearson correlation analyses revealed that the bacterial communities were primarily regulated by soil characteristics. This suggested that altered land use patterns initiated changes in the chemical properties of the soils, which affected the composition of microbial communities in this area. This provides a scientific basis for the evolutionary mechanism of soil quality, as well as the rational development and utilization of land resources.
Highlights
The microbial communities of soils dominate biogeochemical cycling, while playing key roles in natural ecosystems [1,2,3,4]
The natural secondary forest (QM) possessed the highest total carbon (TC), total nitrogen (TN), and available nitrogen (AN) contents, showing significantly higher values than those found in SL, Pinus koraiensis (PK), and Zea mays (ZM); there were no significant differences with Larix gmelinii (LG)
Our results showed that the composition of Bacteroidetes in all the samples was higher than 1% except for PK
Summary
The microbial communities of soils dominate biogeochemical cycling, while playing key roles in natural ecosystems [1,2,3,4]. Soil microorganisms provide the impetus for the transformation and recycling of soil resident organic matter and elemental nutrients, such as C and N [5,6]. They are incredibly active and diverse, and play invaluable roles in the maintenance of soil structure, conservation of soil fertility, and soil formation and development, and ensuring system stability [7]. Land use and cover changes impact plant litter on the soil surface, as well as environmental conditions (water and heat), the transformation and flow of soil nutrients, and the quantity, composition, and activity of soil microorganisms [16]. Further research is needed to explain the effects, on soil microorganisms, of some land use types, such as secondary forests, plantations and farmland
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