Gao Qian, Yang Jiangshan, Wu Junyang, Zhu Yongli, Fan Diwu, Han Jiangang
Co-Innovation Center for the Sustainable Forestry in Southern China, College of Ecology and Environment, Nanjing Forestry University, Nanjing, China.
National Positioning Observation Station of Hung-tse Lake Wetland Ecosystem in Jiangsu Province, Hongze, China.
Front Microbiol. 2025 Aug 12;16:1647658. doi: 10.3389/fmicb.2025.1647658. eCollection 2025.
Hormesis is a phenomenon in which low doses of toxins stimulate organisms, while high doses have inhibitory effects. Soil heterogeneity nutrient spatial profoundly influences community structure and stress responses by altering the microenvironment around microorganisms. Studies on hormesis in soil ecosystems have made significant progress, but most of them have overlooked the impact of soil nutrient spatial heterogeneity on hormesis. To examine the effects of nutrient spatial heterogeneity on the hormesis of soil ecosystem under cadmium (Cd) stress, we constructed three patches with different spatial nutrient distribution but the same total nutrient content through different spatial discharge patterns. Different levels of Cd stress were applied to the patches, and after incubation, soil respiration rate, content of dissolved organic matter (DOM) and metagenomic characteristics were measured. The results indicated that higher nutrient spatial heterogeneity enhanced the tolerance of soil respiration to Cd stress (the maximum stimulating dose increased from 0.03 to 3.0 mg·kg), and simultaneously improved the compensation capacity ( increased from 0.04 to 21.59). The results also revealed that Cd stress had the least impact on soil microbial diversity of the high heterogeneity samples. The content of DOM initially displayed a hormesis-like phenomenon with increasing Cd stress, followed by a linear increase. Notably, the biphasic change trend became more pronounced as the degree of spatial heterogeneity increased (The maximum stimulation rate of DOM content increases from 10.8 to 22.9%). The hormetic response of soil respiration to nutrient spatial heterogeneity offers novel insights for the identification and mitigation of Cd pollution in ecosystems.
毒物兴奋效应是一种低剂量毒素刺激生物体，而高剂量则具有抑制作用的现象。土壤养分空间异质性通过改变微生物周围的微环境，深刻影响群落结构和应激反应。土壤生态系统中毒物兴奋效应的研究取得了显著进展，但大多数研究都忽略了土壤养分空间异质性对毒物兴奋效应的影响。为了研究镉（Cd）胁迫下养分空间异质性对土壤生态系统毒物兴奋效应的影响，我们通过不同的空间排放模式构建了三个具有不同空间养分分布但总养分含量相同的斑块。对这些斑块施加不同水平的Cd胁迫，培养后测定土壤呼吸速率、溶解有机物（DOM）含量和宏基因组特征。结果表明，较高的养分空间异质性增强了土壤呼吸对Cd胁迫的耐受性（最大刺激剂量从0.03增加到3.0 mg·kg），同时提高了补偿能力（从0.04增加到21.59）。结果还表明，Cd胁迫对高异质性样本的土壤微生物多样性影响最小。DOM含量最初随着Cd胁迫的增加呈现出类似毒物兴奋效应的现象，随后呈线性增加。值得注意的是，随着空间异质性程度的增加，双相变化趋势变得更加明显（DOM含量的最大刺激率从10.8%增加到22.9%）。土壤呼吸对养分空间异质性的毒物兴奋响应为生态系统中Cd污染的识别和缓解提供了新的见解。
