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.

上层土壤层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。近期研究表明，相较于细菌基食物网（bacterial-based food webs），真菌群落（fungal communities）以及真菌基食物网（fungal-based food webs）对土壤干燥化的敏感性更低、适应性更强。真菌更适应土壤干燥化的原因之一，可能是菌丝网络（mycelia networks）可介导水分再分配（hydraulic redistribution）。本研究发现，腐生真菌双孢蘑菇（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，处理72小时后可提升土壤水势（soil water potential）。在168小时的培养周期内，通过水分再分配提升的土壤湿度，可使先前干燥土壤区域的碳矿化（carbon mineralization）水平提升2800%，酶活性（enzymatic activity）提升250%~350%。研究结果证实，若菌丝网络的其他区域存在可利用水分，水分再分配可部分弥补干燥土壤的水分缺失。水分再分配或许是相较于细菌，土壤真菌具备更高抗旱性（drought resistance）的核心机制之一。此外，腐生真菌介导的水分再分配是土壤中一种长期被低估的水分运输途径，可能会将水分转运至真菌活性较高的区域。