Biological soil crusts as drivers for ecosystem structures and functions on reclaimed post-mining sites in Lower Lusatia, Germany
Stella Gysper and Maik Veste
Surface mining activities are often large-scale disturbances which affect entire landscapes and ecosystem processes. Reclaimed ecosystems undergo long periods of succession for full recovery. These initial soils, consisting of excavated and dumped material, are characterized by a high vulnerability to erosion, low water-holding capacity, lack of nutrients, low pH, or sparse vegetation. Stress-tolerant microorganisms colonize the new soil surface in reclaimed areas. On the upper few millimeters of the topsoil they form a biological soil crust (biocrust) containing cyanobacteria, bacteria, green algae, mosses, lichens and fungi, which crosslink soil particles. The successional development of biocrusts communities and the resulting spatiotemporal heterogeneity of biocrust patches in the landscape depend on various abiotic factors, e.g., surface stability, soil chemistry, microclimate and surface wetness. The different successional stages are characterized by different composition and structures, which vary from initial greenalgae dominated biocrusts to moss-soil lichens crusts (1). We investigated the influence of biocrust succession on ecosystem processes on different reclaimed soils in the opencast lignite mining district of Lower Lusatia (Brandenburg). Photosynthetic activity and community respiration were measured in relation to successional stage and species composition. As photoautotroph microbiotic communities they contribute to carbon accumulation and soil formation of initial soils (2). Furthermore, they change hydrological properties of the soil surface (3) and alternate sub-critical water hydrophobicity. The ecophysiological processes of the biocrusts organisms are highly dependent on water availability, differing in time and space. Therefore, the determination of spatial biocrust activity and photosynthetic capacity was linked by using the latest digital imaging systems for NDVI and chlorophyll fluorescence (4) in the lab and field, and climatic parameters (radiation, temperature, precipitation), and surface wetness duration. The advantages of biocrusts can be used for supporting restoration measures for physical stabilization, gain of organic carbon, and the establishment of natural open grasslands during primary succession.
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(4) Gypser S., et al. 2016. Infiltration and water retention of biological soil crusts on reclaimed soils of former open-cast lignite mining sites in Brandenburg, north-east Germany. J. Hydrol. Hydromech. 64 (1), 1–11.
BIOGEOMON 2017 – 9th International Symposium on Ecosystem Behavior August 20-24, 2017 Litomyšl Chateau, Czech Republic