喀斯特石山老龄林檵木根际和非根际土壤微生物群落及酶活性的旱、雨季节变化

Variations of microbial communities and enzyme activities in rhizosphere and non-rhizosphere soils of aged Loropetalum chinense forests in karst rocky mountains during dry and rainy seasons

关键词:  喀斯特, 檵木群落, 老龄林, 旱雨季, 根际土壤, 土壤酶, 土壤微生物

Key words:  karst, Loropetalum chinense community, aging forest, dry and rainy seasons, rhizosphere soil, soil enzymes, soil microorganisms

摘要:

为了解喀斯特地区土壤生物活性的季节变化及其影响因素,该文以檵木群落老龄林阶段根际和非根际土壤微生物群落为研究对象,探讨其酶活性变化以及与环境因子的关系。结果表明:(1)雨季时,根际土壤pH值、有机质、全碳、全氮、全钾、全磷含量和碱性磷酸酶、过氧化氢酶、脲酶活性低于非根际土壤,说明根际土壤养分淋失更严重且影响相关酶活性,旱季变化相反是根际土壤为供植物健康生长所采取的养分富集策略。(2)根际和非根际土壤真菌多样性为旱季显著高于雨季,非根际土壤细菌多样性为雨季显著高于旱季,但根际土壤细菌多样性季节差异不明显; 无论旱季还是雨季,根际和非根际土壤优势真菌门为子囊菌门(Ascomycota)、被孢霉门(Mortierellomycota)和担子菌门(Basidiomycota),优势细菌门为放线菌门(Actinobacteriota)、变形菌门(Proteobacteria)、酸杆菌门(Acidobacteriota); 季节变化对根际和非根际土壤微生物群落结构影响差异显著。(3)不同季节下根际和非根际土壤微生物群落的主导因子不同,雨季时,根际土壤为pH、过氧化氢酶和碱性磷酸酶活性,非根际土壤为过氧化氢酶、碱性磷酸酶、纤维素酶活性和全钾含量; 旱季时,根际土壤为过氧化氢酶活性和土壤含水量,非根际土壤为纤维素酶和蔗糖酶活性; 土壤酶活性与碳、氮、磷、钾及土壤含水量显著相关。(4)与细菌相比,根际和非根际土壤真菌功能对季节变化的响应更敏感。综上表明,根际和非根际土壤微生物群落及酶活性在雨季和旱季时所采取的适应性策略明显不同,这为喀斯特地区植被恢复和土壤演替提供了理论参考。

Abstract:

To understand the seasonal changes and influencing factors of soil biological activity in karst areas, we investigated the changes in rhizosphere and non-rhizosphere soil microbial communities and enzyme activity of the Loropetalum chinense community in the aged forest stage of karst areas, as well as their relationships with environmental factors. The results were as follows:(1)During the rainy season, the pH value, organic matter, total carbon, total nitrogen, total potassium, total phosphorus contents, and alkaline phosphatase, catalase, and urease activities of rhizosphere soil were lower than those of non-rhizosphere soil, indicating that nutrient leaching in rhizosphere soil was more severe and affected the activity of related enzymes. In contrast, the changes in dry season were nutrient enrichment strategies adopted by rhizosphere soil for healthy plant growth.(2)The diversities of fungi in rhizosphere and non-rhizosphere soils were both significantly higher in the dry season than in the rainy season; the bacterial diversity of non-rhizosphere soil was significantly higher in the rainy season than in the dry season, but the seasonal differences in bacterial diversity of rhizosphere soil were not significant. Regardless of the dry and rainy seasons, the dominant fungal phyla in rhizosphere and non-rhizosphere soils were Ascomycota, Mortierellomycota, and Basidiomycota, while the dominant bacterial phyla were Actinobacteriota, Proteobacteria, and Acidobacteriota. The seasonal changes had significant differences in the structure of microbial communities in rhizosphere and non-rhizosphere soils.(3)The dominant factors of rhizosphere and non-rhizosphere soil microbial communities varied in different seasons. During the rainy season, the rhizosphere soil exhibited pH, catalase and alkaline phosphatase activities, while non-rhizosphere soil exhibited catalase, alkaline phosphatase, cellulase activities, and total potassium content; during the dry season, the rhizosphere soil exhibited catalase activity and soil water content, while non-rhizosphere soil exhibited cellulase and sucrase activity. In addition, soil enzyme activity was significantly correlated with carbon, nitrogen, phosphorus, potassium, and soil water content.(4)Compared to bacteria, fungal functions in rhizosphere and non-rhizosphere soils were more sensitive to seasonal changes. In summary, the adaptive strategies adopted for microbial communities and enzyme activities in rhizosphere and non-rhizosphere soils during the rainy and dry seasons are significantly different. The research results provide theoretical references for vegetation restoration and soil succession in karst areas.