The effects of grazing on root exudates of dominant species in an alpine meadow of the eastern Tibetan Plateau

Abstract

Root exudates are the key substances in regulating soil nutrient cycling, and they have pivotal impacts on soil microbial activity and organic matter decomposition. This paper aimed to clarify secretion rates and changes of root exudates under grazing condition. We conducted a grazing management experiment and adopted in situ method to measure root exudates of the dominant species Elymus nutans under different grazing intensities (no grazing, light grazing, heavy grazing) and different days after grazing stopped (1 day and 21 day) during the peak growing season in an alpine meadow of the eastern Tibetan Plateau. The results showed an average rate of root exudates of E. nutans as 851.29 μg C g-1 root h-1 during the peak growing season. The rate of root exudates was significantly higher in light grazing than no grazing, but there was no significant difference between heavy grazing and no grazing. The rate of root exudation 1 day after grazing showed no significant difference from that of no grazing, while the rate was significantly higher in 21 day after grazing than in 1 day after grazing and the no grazing. This study showed that both light grazing and rest grazing could enhance the rate of root exudation, therefore beneficial to maintenance of soil fertility in an alpine meadow ecosystem.