Converting croplands to orchards changes soil microbial community composition and co‐occurrence patterns

Abstract

Soil microorganisms are key to uncovering the mechanisms driving variation in soil biogeochemical processes associated with land-use change. A large number of croplands have been converted to orchards on the Chinese Loess Plateau due to the increased economic benefits which result. However, the microbial community and their functional composition remain poorly understood. In this study, soil samples were collected from croplands and orchards. Soil physicochemical properties and the community (represented by 16S rRNA for bacteria and ITS for fungi) were measured, and interactions among species and the soil organic matter (SOM) degradation via microbial metabolism and its associated genes were analyzed. Croplands converted to orchards affected bacterial and fungal community structure by increasing the relative abundance of Proteobacteria, Bacteroidetes, Firmicutes, Actinobacteria, and Ascomycota, whereas it decreased the α-diversity of bacteria and fungi. The cooccurrence network was larger and more complex within croplands than within orchards, indicating more extensive interactions and higher community stability potential. The abundance of potential genes related to cellulose and hemicellulose metabolism in orchards was higher than that in croplands, whereas the abundance of genes related to lignin decomposition was lower than that in croplands. In addition, the abundance of saprotrophic and symbiotrophic fungi in orchards was significantly lower than that in croplands (27 and 88%, respectively), whereas the abundance of pathotrophic fungi in orchards was almost six-times that in croplands. The soil organic carbon (SOC) and soil C:N in orchards were significantly lower than that in croplands. Converting croplands to orchards significantly altered the microbial community composition and their functionality, as well as decreased the complexity of interaction between microorganisms. The decreased SOC and increased soil C:N ratio could be attributed to these variations. Improved management practices should be implemented for the maintenance of soil biodiversity and SOC in orchards to avoid soil degradation and ensure sustainable development.

Microbiological mechanism underlying vegetation restoration across climatic gradients in a karst ecosystem

“…We demonstrated that the bacterial phyla Acidobacteria and Proteobacteria, fungal phyla Ascomycota and Basidiomycota, and protist phyla Cercozoa and Lobosa formed the most links with other microbial groups and are, therefore, potentially vital to soil food webs (Figure 4, Table S5), which indicated that these taxa are keystone and indicator taxa in the co‐occurrence patterns (Fournier et al, 2020; Wang, Wang, et al, 2021). Moreover, these taxa were the dominant groups in the microbial community, suggesting that a microbiome containing these taxa with a high abundance may have more links among groups than that with a low relative abundance.…”

The response of soil respiration to land‐use change depends on soil microbial community being regulated by edaphic factors in the Loess Plateau, China

“…In view of their important functions in the soil carbon cycle (Chang et al, 2021; Yang et al, 2020), it was reasonable to believe that there were interactions among them. Nevertheless, a higher complex co‐occurrence network was found in farmland than in plantation/grassland, which resulted in higher community stability and interactions in farmland (Wang et al, 2021). The average path length was shorter in farmland than in plantation/grassland, which indicated that farmland might rapidly respond to variations of soil physicochemical factors through efficient pathways (Wang et al, 2021).…”

Soil Bacterial Community Shifts Are Driven by Soil Nutrient Availability along a Teak Plantation Chronosequence in Tropical Forests in China

“…This indicates that most soil bacterial taxa may synergistically act or share similar ecological niches in the soil environment of teak plantations [ 72 ]. In addition, an increase in positive associations was observed with stand age, suggesting that the co-occurrence network between synergistic bacterial groups was enhanced [ 72 , 78 ]. We also found that the average path length (APL) value in the 45-y sites was the smallest, indicating that it was a small-world network [ 74 ].…”

“…We also found that the average path length (APL) value in the 45-y sites was the smallest, indicating that it was a small-world network [ 74 ]. The small-world network indicates that the bacterial community can respond quickly to changes in external environmental conditions [ 78 ]. Network analysis can not only be applied to determine how species occur together in niches but can also identify the keystone taxa that play a critical role in communities [ 79 , 80 ].…”