Functional Diversity of Soil Microorganisms and Influencing Factors in Three Typical Water-Conservation Forests in Danjiangkou Reservoir Area

Abstract

As a key part of the forest ecosystem, soil microorganisms play extremely important roles in maintaining the ecological environment and the security of water quality in reservoir areas. However, it is not clear whether there are differences in the functional diversity of soil microorganisms in different types of water−conservation forests in reservoir areas, and which factors affect the functional diversity of soil microorganisms. In our study, the Biolog−Eco microplate technique was used to analyze the carbon source metabolic characteristics of soil microbial communities in three typical water−conservation forests and a non−forest land: Pinus massoniana−Quercus variabilis mixed forest (MF), Pinus massoniana forest (PF), Quercus variabilis forest (QF) and non−forest land (CK). The results showed that the average well color development (AWCD), the Shannon diversity index (SDI) and the richness index (S) of the three forest lands was significantly greater than that of the non−forest land (p < 0.05). The mean values of AWCD, SDI and S of the three forests had the same order (QF > PF > MF), but there was no significant difference among different types of forests. The microbial biomass carbon (MBC) and microbial biomass nitrogen (MBN) of QF and PF were higher than those of MF and CK, but the microbial biomass C/N ratio (MBC/MBN) was lower. The variance partitioning analysis (VPA) showed that 86.4% of the variation was explained by plant (community) diversity, soil physical and chemical properties and soil microbial biomass, which independently explained 10.0%, 28.9%, and 14.9% of the variation, respectively. The redundancy analysis (RDA) showed that total phosphorus (TP), microbial biomass carbon (MBC), total nitrogen (TN), number of plant species (Num) and alkali-hydro nitrogen (Wn) were the key factors affecting the functional diversity of soil microorganisms. This study confirmed that forest ecosystem is better than non−forest land in maintaining soil microbial function diversity. Moreover, Quercus variabilis forest may be a better stand type in maintaining the diversity of soil microbial functions in the study area.

Analysis on metabolic functions of rhizosphere microbial communities of Pinus massoniana provenances with different carbon storage by Biolog Eco microplates

“…Larger loading scores indicate a stronger influence of the carbon source on the principal component. Carbon sources with an absolute value greater than 0.6 are considered the main types of carbon sources utilized by the soil microbial community ( Yao Z. W. et al, 2023 ). As can be seen from the results in Table 2 , there are 10 types of carbon sources that primarily affect PC1.…”

“…The AWCD values of the high carbon storage provenances SM and AY were significantly higher than those of other provenances at each period of the 240 h culture in this study. These differences can be attributed to plant species, root exudates, litter decomposition, and plant residues ( Yao Z. W. et al, 2023 ). Both Shannon diversity and Simpson diversity of rhizosphere microorganisms with high carbon storage provenances (SM and AY) were significantly higher than those from medium and low carbon storage ( p < 0.05).…”

“…The results showed that the microbial functional diversity of rhizosphere soil in high carbon storage provenances was significantly higher than that in medium and low carbon storage provenances. Rhizosphere microorganisms from high carbon storage provenance exhibited a greater ability to utilize various carbon sources ( Yao Z. W. et al, 2023 ). On the whole, high carbon storage provenances exhibited enhanced forest ecological functions.…”

“…Forest ecosystems play a pivotal role in maintaining the functional diversity of soil microorganisms. There are differences in the maintenance of functional diversity among soil microorganisms across different forest stand types ( Yao Z. W. et al, 2023 ). However, there have been limited studies on the effects of plant carbon storage levels on the functional diversity of soil microorganisms.…”

“…They provide comprehensive information on the function of six types of soil microorganisms, including 31 carbon sources, for microbial community analysis ( Zhang et al, 2023 ). Studies have shown that plant diversity ( Zhu et al, 2015 ) and forest type are closely linked to soil microbial functional diversity ( Yao Z. W. et al, 2023 ), influencing soil microbial structure, activity, and biomass. Although these studies have focused on the correlation between above-ground vegetation and soil microorganisms, few have investigated the impact of woody plants with different levels of carbon storage on soil microbial functional diversity using the Biolog Eco microplates.…”