关键词: 湿地低温胁迫, 植被, 活性微生物, 抵抗力和恢复力, 纤维素酶活性

Abstract:

Objective: This study aims to investigate the dynamic changes of soil active microbial communities in different wetland vegetation types under winter low-temperature stress, in order to elucidate the microbiological mechanisms that maintain key ecological functions (cellulose degradation) of wetland ecosystems under low-temperature conditions. Method: Soil samples were collected from Typha orientalis and Iris tectorum fields in November 2021 (before low-temperature stress), January 2022 (during low-temperature stress), and March 2022 (after low-temperature stress relief) during winter and spring. RNA was extracted for high-throughput sequencing, and cellulase activity was determined using the 3,5-dinitrosalicylic acid (DNS) colorimetric method. Resistance and resilience of active microbial communities to low-temperature stress were calculated. Two-way ANOVA, regression analysis, network analysis, heatmap analysis, and random forest models were used to reveal the effects of temperature and vegetation type on active microbial communities and cellulase activity, and to identify the microbial taxa that most influenced enzyme activity. Result: 1) Temperature significantly affected the richness of soil active microbial communities (P < 0.001), and different dominant microbial taxa exhibited distinct response strategies. Proteobacteria and Bacteroidota showed high resistance to low-temperature stress, while Acidobacteriota, Actinobacteriota, Cyanobacteria, Firmicutes, Nitrospirota, and Planctomycetota showed low resistance. 2) There was no significant difference in soil microbial community richness between T. orientalis and I. tectorum fields, but the soil active microorganisms in the I. tectorum field showed higher resistance and resilience to low-temperature stress, and its microbial co-occurrence network was more complex. 3) Soil cellulase activity was significantly affected by soil temperature (P < 0.01), but showed no significant difference between vegetation types. Random forest model analysis indicated that Acidobacteriota was the most important microbial taxon affecting cellulase activity. Conclusion: Low-temperature stress is a key factor affecting active microbial communities, while vegetation can improve the adaptability of active microbes to low-temperature stress by enhancing the stability and interspecific interactions of microbial communities. Proper vegetation allocation is beneficial for maintaining wetland ecosystem functions under low-temperature conditions.

Key words: wetland low-temperature stress, vegetation, active microbes, resistance and resilience, cellulase activity