Wang Xiaonan, Zhou Chengyang, Zuo Shining, Ji Yixin, Liu Wenxin, Huang Ding
College of Grassland Science and Technology, China Agricultural University, Beijing, China.
PeerJ. 2024 Mar 7;12:e17031. doi: 10.7717/peerj.17031. eCollection 2024.
In a context of long-term highly intensive grazing in grassland ecosystems, a better understanding of how quickly belowground biodiversity responds to grazing is required, especially for soil microbial diversity.
In this study, we conducted a grazing experiment which included the CK (no grazing with a fenced enclosure undisturbed by livestock), light and heavy grazing treatments in a desert steppe in Inner Mongolia, China. Microbial diversity and soil chemical properties (., pH value, organic carbon, inorganic nitrogen (IN, -N and -N), total carbon, nitrogen, phosphorus, and available phosphorus content) both in rhizosphere and non-rhizosphere soils were analyzed to explore the responses of microbial diversity to grazing intensity and the underlying mechanisms.
The results showed that heavy grazing only deceased bacterial diversity in the non-rhizosphere soil, but had no any significant effects on fungal diversity regardless of rhizosphere or non-rhizosphere soils. Bacterial diversity in the rhizosphere soil was higher than that of non-rhizosphere soil only in the heavy grazing treatment. Also, heavy grazing significantly increased soil pH value but deceased NH4+-N and available phosphorus in the non-rhizosphere soil. Spearman correlation analysis showed that soil pH value was significantly negatively correlated with the bacterial diversity in the non-rhizosphere soil. Combined, our results suggest that heavy grazing decreased soil bacterial diversity in the non-rhizosphere soil by increasing soil pH value, which may be due to the accumulation of dung and urine from livestock. Our results highlight that soil pH value may be the main factor driving soil microbial diversity in grazing ecosystems, and these results can provide scientific basis for grassland management and ecological restoration in arid and semi-arid area.
在草地生态系统长期高度密集放牧的背景下，需要更好地了解地下生物多样性对放牧的响应速度，特别是土壤微生物多样性。
在本研究中，我们在中国内蒙古的一个荒漠草原进行了一项放牧实验，该实验包括对照（用围栏围起来不让牲畜干扰的不放牧处理）、轻度放牧和重度放牧处理。分析了根际和非根际土壤中的微生物多样性以及土壤化学性质（如pH值、有机碳、无机氮（铵态氮和硝态氮）、总碳、氮、磷和有效磷含量），以探讨微生物多样性对放牧强度的响应及其潜在机制。
结果表明，重度放牧仅降低了非根际土壤中的细菌多样性，但对根际或非根际土壤中的真菌多样性均无显著影响。仅在重度放牧处理中，根际土壤中的细菌多样性高于非根际土壤。此外，重度放牧显著提高了土壤pH值，但降低了非根际土壤中的铵态氮和有效磷。Spearman相关性分析表明，土壤pH值与非根际土壤中的细菌多样性显著负相关。综合来看，我们的结果表明，重度放牧通过提高土壤pH值降低了非根际土壤中的细菌多样性，这可能是由于牲畜粪便和尿液的积累。我们的结果强调，土壤pH值可能是驱动放牧生态系统中土壤微生物多样性的主要因素，这些结果可为干旱和半干旱地区的草地管理和生态恢复提供科学依据。
