Water Level Has Higher Influence on Soil Organic Carbon and Microbial Community in Poyang Lake Wetland Than Vegetation Type

Abstract

Although microorganisms play a key role in the carbon cycle of the Poyang Lake wetland, the relationship between soil microbial community structure and organic carbon characteristics is unknown. Herein, high-throughput sequencing technology was used to explore the effects of water level (low and high levels above the water table) and vegetation types (Persicaria hydropiper and Triarrhena lutarioriparia) on microbial community characteristics in the Poyang Lake wetland, and the relationships between soil microbial and organic carbon characteristics were revealed. The results showed that water level had a significant effect on organic carbon characteristics, and that soil total nitrogen, organic carbon, recombinant organic carbon, particle organic carbon, and microbial biomass carbon were higher at low levels above the water table. A positive correlation was noted between soil water content and organic carbon characteristics. Water level and vegetation type significantly affected soil bacterial and fungal diversity, with water level exerting a higher effect than vegetation type. The impacts of water level and vegetation type were higher on fungi than on bacteria. The bacterial diversity and evenness were significantly higher at high levels above the water table, whereas an opposite trend was noted among fungi. The bacterial and fungal richness in T. lutarioriparia community soil was higher than that in P. hydropiper community soil. Although both water level and vegetation type had significant effects on bacterial and fungal community structures, the water level had a higher impact than vegetation type. The bacterial and fungal community changes were the opposite at different water levels but remained the same in different vegetation soils. The organic carbon characteristics of wetland soil were negatively correlated with bacterial diversity but positively correlated with fungal diversity. Soil water content, soluble organic carbon, C/N, and microbial biomass carbon were the key soil factors affecting the wetland microbial community. Acidobacteria, Alphaproteobacteria, Verrucomicrobia, Gammaproteobacteria, and Eurotiomycetes were the key microbiota affecting the soil carbon cycle in the Poyang Lake wetland. Thus, water and carbon sources were the limiting factors for bacteria and fungi in wetlands with low soil water content (30%). Hence, the results provided a theoretical basis for understanding the microbial-driven mechanism of the wetland carbon cycle.

Net Methane Production Predicted by Patch Characteristics in a Freshwater Wetland

“…The accumulation of litter we observed, however, may indicate poor quality and slow decomposition, which is supported by its high litter C:N ratio and decomposition rate compared to other wetland graminoids (Moran et al., 1989). High [CO 2 ] in FORB patches may also be related to litter quality as similar species have very low C:N (Ren et al., 2022).…”

Discrepant Effects of Flooding on Assembly Processes of Abundant and Rare Communities in Riparian Soils

“…Compared to higher elevations, riparian soils at lower elevations were more frequently affected by ooding, which signi cantly increased the alpha diversity of the microbial community. This may be related to the higher nutrient availability of frequently-ooded soils which have greater exchange rate with the aquatic system and thus more extensive nutrients cycling [32]. Indeed, ooding can carry large amounts of nutrients from upland soils to later deposit in lower elevation soil [6].…”

Flooding determines the assembly process of archaeal and bacterial communities in soil

“…Compared to higher elevations, riparian soils at lower elevations were more frequently affected by flooding, which significantly increased the alpha diversity of the microbial community. This may be related to the higher nutrient availability of flooded soils which have more extensive nutrients cycling and exchange rate with the aquatic system (Ren et al, 2022 ). Besides, flooding can carry large amounts of nutrients from upland soils to later deposit in lower elevation soil (Ye et al, 2019 ).…”