Effect of Different Grain for Green Approaches on Soil Bacterial Community in a Karst Region

Abstract

Soil bacteria participate in nutrient cycling above and below ground to promote ecosystem stability and health. However, the relationship of soil bacteria and environmental factors following the Grain for Green (GfG) program remains poorly understood in southwest China. Soil samples were collected from seven Grain for Green sites that had been revegetated for 15 years. Four of these sites were afforested with a different tree species: Zenia insignis (ZI), Toona sinensis (TS), Castanea mollissima (CM), and Citrus reticulate (CR). One site was revegetated with Zenia insignis and Guimu-1 elephant grass (ZG), and one with only Guimu-1 elephant grass (GM). The remaining site, abandoned cropland (AC), was left to regenerate naturally. Here, we used Illumina sequencing of 16S rRNA genes to explore how the Grain for Green project affected soil bacterial community. We found that Actinobacteria, Proteobacteria, Chloroflexi, and Acidobacteria were the dominant phyla in these soils. The dominant genera at each revegetation site were also different. The CM, ZI, TS, and AC sites were dominated by Micromonospora, ZG was dominated by Streptomyces, and CR and GM were dominated by Subgroup 6. The bacterial structure was most similar in AC and TS. Correlation analysis showed that the ratio of C:P had positive effects on KD4-96, Intrasporangiaceae, and Gaiella. The ratio of soil N:P was significantly positively correlated with Cupriavidus and Kribbella. The combination of planting Zenia insignis and Guimu-1 elephant grass had the best edaphic benefits, and the approach of planting Citrus reticulate and Toona sinensis needs to be improved. Redundancy analysis (RDA) revealed that plant Simpson index, and soil N:P contributed to 16 and 15.7% of the total variations in the soil bacterial community composition, respectively. Our results suggested that plant diversity (Simpson index) and soil stoichiometric ratio (N:P) were the important factors affecting the bacterial community, and phosphorus was the limiting factor of the bacterial community in the Grain for Green karst region. In the future, revegetation should be accompanied with phosphorus fertilizer and polycultures should be considered.

Effect of Cultivated Pastures on Soil Bacterial Communities in the Karst Rocky Desertification Area

“…After 10 years of vegetation restoration, there were significant differences in soil properties under different vegetation restoration treatments. The related studies have shown that converting land use from agriculture to cultivated pasture reduced soil acidity (Chen et al, 2020), which was consistent with the findings in this study that DG, LP, and LT treatments reduced soil pH. This may be because cultivated pasture has higher aboveground biomass, which can produce a large amount of easily decomposable litter, increase the community of burrowing animals, and accelerate the cation cycle in the grassland ecosystem, thereby offsetting soil acidification (Paudel et al, 2021).…”

“…The karst area in southern China with Guizhou as the center reaches 1.24 million km 2 , with the largest area of continuous exposed carbonate rocks and the strongest karst development among the three major karst-concentrated distribution areas in the world ( Xiong et al, 2002 ). The karst parent rock has a slow soil formation rate, shallow soil layers, broken ground, and concentrated rainstorms, especially disturbed by traditional unprotected farming activities, which can easily cause damage to native vegetation, serious soil erosion, and rocky desertification ( Xiong et al, 2017 ; Chen et al, 2020 ; Hu and Lan, 2020 ). Karst rocky desertification is a land degradation process that includes severe soil erosion, extensive exposure of bedrocks, sharp decline in soil productivity, and the emergence of desert-like landscapes, which had become the main ecological disaster that seriously hinders the economic development of southwest China ( Xiong et al, 2002 ).…”

“…However, there less research that has been done on the restoration of artificial vegetation in karst areas ( Lu et al, 2022 ). Furthermore, few studies have focused on bacterial communities and environmental factors under several different artificial vegetation restorations ( Chen et al, 2020 ). At present, the difference between the natural restoration and artificial grass planting of fragile ecosystems in the karst rocky desertification control area in southwest China is unclear, and also the differences in soil microbial communities between different restorations of cultivated pastures are unclear.…”

Fellfields of the Kerguelen Islands harbour specific soil microbiomes and rhizomicrobiomes of an endemic plant facing necrosis

“…It was only composed of bacterial OTUs that belonged to both widespread and more narrowly distributed taxa (66). These taxa were related to N² fixation (Rhizobiales, Frankiales, Ktedonobacterales and Acetobacterales), adapted to soil with low content in phosphorus (Gemmatales, Microtrichales and Solibacterales) and involved in soil organic matter degradation (Micrococcales and Thermomicrobiales) (67)(68)(69)(70)(71)(72)(73). Together with the unknown fungal communities, this soil core microbiome represented the specificity of the microbial communities of the fellfield soils of the Kerguelen Islands that were composed of both restricted and cosmopolitan microbes.…”

Microbial Community and Their Potential Functions after Natural Vegetation Restoration in Gullies of Farmland in Mollisols of Northeast China

“…For the first path, SOM was negative to soil pH, and then positive to AP and further weakening the bacterial richness. This can attribute to the association between AP and bacterial richness being tight in soils with the limited P [57,58]. In the second path, SOM promoted the storage of water in soils, and then directly negatively associated with bacterial richness and further positively associated with bacterial diversity.…”