Effects of algal crusts in ground fissure areas on soil physicochemical properties and water transport

The ecological environment of coal mining areas in western China is highly fragile.Ground fissures induced by coal extraction subsidence exacerbate soil erosion and degradation. Microbial-based land reclamation has become a research hotspot in ecological restoration of mining areas. This study focuses on elucidating the functional mechanisms by which algal crusts influence soil physicochemical properties and water transport processes in fissured areas, aiming to reveal the key ecological roles in mitigating soil structure degradation and water-nutrient loss. Algal-crusted and bare soils in fissure areas were selected as study objects. Through soil structural analysis, water infiltration and evaporation tests, as well as nutrient content determination, the ecological effects of algal crusts under fissure disturbance were systematically assessed to provide a theoretical basis for artificial algal crust applications in ecological restoration.The results showed that with the increase in fissure scale, soil exhibit higher sand content, reduced silt and clay fractions, decreased surface soil moisture, accelerated infiltration and evaporation rates, and significantly lower nutrient levels.In non-fissured areas, algal crusts improved soil quality significantly, increasing organic carbon, total nitrogen, total phosphorus, and surface moisture content by 91.13%, 27.48%, 23.46%, and 38.77%, respectively, while reducing infiltration rate by 42.9%.In fissure areas, algal crusts alleviate water and nutrient loss effectively, increasing surface soil moisture from 18.36% to 42.85%.Algal crusts exhibit significant functions in water retention and nutrient accumulation, and hold promissing prospects for application in ecological restoration of coal mining subsidence areas.