Data from: Redistribution of soil water by a saprotrophic fungus enhances carbon mineralization

The desiccation of upper soil horizons is a common phenomenon, leading to a decrease in soil microbial activity and mineralization. Recent studies have shown that fungal communities and fungal-based food webs are less sensitive and better adapted to soil desiccation than bacterial-based food webs. One reason for a better fungal adaptation to soil desiccation may be hydraulic redistribution of water by mycelia networks. Here we show that a saprotrophic fungus (Agaricus bisporus) redistributes water from moist (–0.03 MPa) into dry (–9.5 MPa) soil at about 0.3 cm⋅min−1 in single hyphae, resulting in an increase in soil water potential after 72 h. The increase in soil moisture by hydraulic redistribution significantly enhanced carbon mineralization by 2,800% and enzymatic activity by 250–350% in the previously dry soil compartment within 168 h. Our results demonstrate that hydraulic redistribution can partly compensate water deficiency if water is available in other zones of the mycelia network. Hydraulic redistribution is likely one of the mechanisms behind higher drought resistance of soil fungi compared with bacteria. Moreover, hydraulic redistribution by saprotrophic fungi is an underrated pathway of water transport in soils and may lead to a transfer of water to zones of high fungal activity.

上层土壤的干燥化是一种常见现象，会导致土壤微生物活性与矿化作用降低。已有研究表明，相较于以细菌为基础的食物网，真菌群落及真菌基食物网对土壤干燥化的敏感性更低、适应性更强。真菌对土壤干燥化适应性更强的原因之一，可能是菌丝网络介导的水分水力再分配（hydraulic redistribution）作用。本研究证实，一种腐生真菌（saprotrophic fungus）——双孢蘑菇（Agaricus bisporus），可通过单根菌丝以约0.3 cm·min⁻¹的速率，将水分从湿润（-0.03 MPa）土壤转运至干燥（-9.5 MPa）土壤，使72小时后的土壤水势得到提升。在168小时内，水力再分配带来的土壤湿度提升，可使此前干燥的土壤隔室的碳矿化作用提升2800%，酶活性提升250%~350%。本研究结果表明，若菌丝网络的其他区域存在可利用水分，水力再分配作用可部分弥补干燥区域的水分亏缺。水力再分配作用可能是相较于细菌，土壤真菌具备更强抗旱性的潜在机制之一。此外，腐生真菌介导的水力再分配作用是一种长期被低估的土壤水分运移途径，还可将水分转运至真菌活性较高的土壤区域。