Abstract

Soil bacteria play a key role in the ecological and evolutionary responses of agricultural ecosystems. Domestic herbivore grazing is known to influence soil bacterial community. However, the effects of grazing and its major driving factors on soil bacterial community remain unknown for different plant community compositions under increasing grazing intensity. Thus, to investigate soil bacterial community diversity under five plant community compositions (Grass; Leymus chinensis; Forb; L. chinensis & Forb; and Legume), we performed a four-year field experiment with different grazing intensity treatments (no grazing; light grazing, 4 sheep·ha−1; and heavy grazing, 6 sheep·ha−1) in a grassland in China. Total DNA was obtained from soil samples collected from the plots in August, and polymerase chain reaction (PCR) analysis and denaturing gradient gel electrophoresis (DGGE) fingerprinting were used to investigate soil bacterial community. The results showed that light grazing significantly increased indices of soil bacterial community diversity for the Forb and Legume groups but not the Grass and L. chinensis groups. Heavy grazing significantly reduced these soil bacterial diversity indices, except for the Pielou evenness index in the Legume group. Further analyses revealed that the soil N/P ratio, electrical conductivity (EC), total nitrogen (TN) and pH were the major environmental factors affecting the soil bacterial community. Our study suggests that the soil bacterial community diversity was influenced by grazing intensity and plant community composition in a meadow steppe. The present study provides a baseline assessment of the soil bacterial community diversity in a temperate meadow steppe.

Highlights

  • ObjectivesThe main objectives of this study were as follows: i. to investigate whether plant community composition affects soil bacterial community composition and diversity; ii. to explore how these changes are affected by intensity of grazing; and iii. to identify the main factors affecting the soil bacterial community in a meadow steppe

  • Soil biodiversity, a key determinant of the ecological and evolutionary responses of terrestrial ecosystems to current and future environmental change, has become a focus of soil ecological research field [1,2]

  • The results for electrical conductivity (EC) were similar to those of pH under the grazing treatments (P < 0.001): EC in the Grass group increased along the grazing gradient, whereas high EC values in the L. chinensis and L. chinensis & Forb groups were only observed with heavy grazing (P < 0.001) (Fig 1b)

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Summary

Objectives

The main objectives of this study were as follows: i. to investigate whether plant community composition affects soil bacterial community composition and diversity; ii. to explore how these changes are affected by intensity of grazing; and iii. to identify the main factors affecting the soil bacterial community in a meadow steppe. The main objectives of this study were as follows: i. To investigate whether plant community composition affects soil bacterial community composition and diversity; ii. To explore how these changes are affected by intensity of grazing; and iii. To identify the main factors affecting the soil bacterial community in a meadow steppe. The objective of this work was to determine the influence of plant community composition on the diversity of soil microbial communities under grazing intensity treatments and to examine whether these effects are context dependent

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