Mining Subsidence-Induced Microtopographic Effects Alter the Interaction of Soil Bacteria in the Sandy Pasture, China

Abstract

The microtopographic changes induced by coal mining subsidence caused a series of environmental problems such as soil erosion, and vegetation degradation in the mining area. However, the corresponding influence on surface vegetation and soil characteristic in different parts of the slope was completely different. To understand soil and vegetation degradation in coal mines and their future ecological restoration, it was crucial to investigate the origin. The relationship between soil microbial community diversity, structure, and taxa in the slope of subsidence area of different topographic locations in Daliuta coal mine, Shannxi, China, was determined by high throughput sequencing and molecular ecological network analysis. The relationship between the bacterial communities, environmental factors, and soil physicochemical properties was also investigated. We found a new topographic trait formed by surface subsidence to deteriorate the living environment of vegetation and the bacterial community. The vegetation coverage, soil water content, organic matter, and urease and dehydrogenase activities decreased significantly (p < 0.05). Although soil bacterial community diversity in the subsidence area did not differ significantly, the dominant taxa in different topographic locations varied. The molecular ecological networks representing bacterial community structure and function were also totally different. The networks in the middle and the top of the slope tend to be more complicated, and the interaction between species is obviously stronger than that of the bottom. However, the network in the bottom slope approached simplicity, and weak interaction, predominantly cooperative, was observed within and between modules. Meanwhile, the double stress of aridity and the lack of carbon source induced by subsidence also enhanced the capacity of the soil bacterial community to metabolize complex carbon sources at the bottom of the slope.

Ecological network analysis to assess the restoration success of disturbed mine soil in Zoucheng, China

“…The reclaimed soil composition has influenced the soil organic matter, which thus might affect the change of total N and Olsen-P contents, which indicated that the soil Contrariwise, the soil pH and EC levels increased over the reclamation timeline, indicating that soil alkalinity increased after reclamation. These observations contradicted earlier studies (Adeli et al, 2013;Zhang et al, 2021) and were likely produced by the presence of a watertable near the ground surface and with high concentration in salt (Qu et al, 2018) resulting from the release of cations (e.g., Ca 2+ , Mg 2+ ) present in the coal gangue from past mining activities (Hu et al, 2015). Another possible source for the increase in soil pH and EC following land reclamation could be the application of inorganic fertilizers by the local farmers (Liu et al, 2018), or the soil materials used for reclaiming the land.…”

“…Figure 3), some other microbial species were somehow stimulated and their abundance increased (Table 2; Figure 3); especially for those species of bacteria that could adapt to special, reclaimed environments (Yuan et al, 2021;Zhang et al, 2021). The analysis of alpha diversity provided herein (Figure 3) reflected the impact of time after land reclamation on the diversity of the SMC.…”

“…SMCs are always sensitive to environmental change. Change in the soil environment due to land reclamation activities could influence the composition and activity of the soil microbial communities (Delgado-Baquerizo et al, 2018;Zhang et al, 2021), likely driving the direction of the natural succession of the communities of soil bacteria (Hüblová & Frouz, 2021;Li et al, 2014). Herein, the species richness increased while the species evenness decreased across the reclamation timeline (Figure 3), which indicated even though the reclamation activities posed a challenge for some species in the soil (Table 2;…”

“…The analysis of alpha diversity provided herein (Figure 3) reflected the impact of time after land reclamation on the diversity of the SMC. The lower evenness observed in the plots subjected to land reclamation may indicate the evolutionary trend of decreasing abundance as the soil's spatial heterogeneity may increase after land reclamation (Zhang et al, 2021).…”

“…Molecular ecological networks (MENs), which use mathematical and bioinformatics methods to construct ecological association networks, and to provide a conceptual framework capable of identifying microbial interactions and key populations, and of relating these with key attributes and functions occurring in the soil compartment (Deng et al, 2016). Moreover, MENs can be useful to identify keystone taxa of soil microorganisms (Ma et al, 2020;Zhang et al, 2021). Keystone taxa play important roles in the microbiome, such as driving community composition and functionality, and their variation might cause changes in microbiome composition and functioning (Delgado-Baquerizo et al, 2018).…”