关键词: 油茶林, 生草栽培, 土壤微生物, 群落结构, 群落稳定性

Abstract:

Objective: The aim of this study was to explore the effect of herbage inter-planting on the stability of soil microbial community of Camellia oleifera plantations in southern red soil region. These findings would provide the theoretical basis for sustainable management of C. oleifera plantation. Method: The structure of soil microorganisms of C. oleifera plantations respectively with tending and weeding (TF), preserving natural weeds (TZ), inter-planting of Coreopsis basalis (TJ) and inter-planting of Paspalum notatum (TB) was studied by high-throughput sequencing method, the abundance pattern of soil microbial community was analyzed by using brokenstick, Zipf, Mandelbrot and other models, and the community aggregation process was inferred by zero modeling method. The stability of microbial community was evaluated by the average variation degree of community, and the interaction between microbial communities was predicted by network analysis. Result: There were differences in soil nutrients and enzyme activities under different herbage inter-planting treatments. The contents of total carbon, total nitrogen, available nitrogen, and available phosphorus were the highest in TF treatment, and there was no significant difference in soil nutrients and enzyme activities between TF and TB. The composition of soil microbial community under TF, TJ, and TB treatments were similar. Among them, Proteobacteria and Acidobacteria were the dominant phyla, accounting for more than 50% of the total soil microbial. Koribacteraceae was the dominant family, accounting for more than 12% of the total. The dominant phyla of TZ treatment were Proteobacteria and Bacteroidetes, accounting for 55.1%, and the dominant family was comamonadaceae, accounting for 12.8%. Zipf Mandelbrot model had the best fitting effect on soil microbial abundance pattern. The species structure of soil microbial community under TZ treatment was the most balanced, with a small decrease in abundance and a weak dominance of dominant species in soil microbial community. The balance of community structure in TF and TB treatments was poor. There were significant differences in the stability of soil microbial communities among different herbage inter-planting treatments. The average variation degree value (AVD) of TF treatment was 0.411, indicating that the stability of soil microbial communities was the strongest. The AVD value of TZ treatment was 0.634, indicating that the stability of soil microbial communities was the worst. The absolute value of beta nearest taxon index (βNTI) between each treatment was bigger than 2, indicating that the change of microbial community was a deterministic assembly process, and the change of microbial community structure was mainly affected by decisive factors. The β diversity of microbial community was significantly positively correlated with the environmental distance. When the genetic difference was eliminated, the environment still had a significant indigenous effect on community construction, while the genetic distance and the genetic distance to eliminate the environmental distance had no significant indigenous effect on community construction, that is, habitat filtering had an effect on the construction of soil microbial community in C. oleifera plantation. Delftia, Methylotenera, Rhodoferax, Sphingobium and Veillonella were the core genera for maintaining the network stability under herbage inter-planting treatments. The effects of soil environment on dominant flora were studied, and the results showed that Proteobacteria and Chloroflexi were not sensitive to environmental changes, and the effect of total potassium content on Acidobacteria was extremely significant, while that on Actinobacteria and Firmicutes was significant. Total phosphorus content had a significant effect on Firmicutes. Conclusion: The herbage inter-planting had an effect on the stability of soil microbial community in C. oleifera plantations in red soil area in southern China. Soil potassium content significantly affected the structure and stability of microbial community, and P. notatum is more suitable for herbage inter-planting in C. oleifera plantations. It is not suitable to inter-plant natural weeds in C.oleifera plantations, which can reduce soil nutrient content and soil microbial community stability. Although tillage and tending weeding improved the stability of soil microbial community, its composition pattern was not balanced. The long-term clearing and weeding would cause the loss of rare populations and may weaken the ecological service function.

Key words: Camellia oleifera plantation, herbage planting, soil microorganism, community structure, community stability