Las comunidades criptógamas como potenciales indicadores de recuperación post-fuego en el pedemonte

Abstract

Among the disturbances affecting terrestrial ecosystems, fire is one of the most important in the Monte ecoregion of Argentina. In the foothills, recurrent fires generate changes in the composition of the vegetation and the physiognomy of the landscape, without knowledge of the effects of fire on cryptogams. Cryptogams include biological soil crusts (BSC), corticolous and saxicolous lichens, and mosses. These communities are crucial in degraded ecosystems and in arid zones by fixing nitrogen and stabilizing the soil. Furthermore, some of the organisms of BSC develop quite slowly and are sensitive to disturbances, which makes them potentially useful as indicators of disturbance or recovery. In this work, we evaluate the cover and frequency of functional types of cryptogams, as well as the environmental factors that favor their development in sites with different fire histories, in order to identify potential indicators of post-fire recovery. We found that saxicolous and corticolous lichen frequency, BSC cover and cyanobacterial-dominated BSC frequency varied as a function of post-fire recovery time. Their cover and frequency were also affected by the cover of vascular plants, bare soil, rocks and mounds generated by animals. These variations in abundance can be used as indicators of the success of passive ecological restoration strategies. Corticolous and saxicolous lichens may function as indicators of post-fire recovery as they are only present on sites with +40 years since the latest fire and showed a greater response than vascular plants. On the other hand, CBS dominated by cyanobacteria —being more abundant in sites with recent fires— would be good indicators of more recent soil recovery processes. The wide distribution of BSC dominated by mosses, and the development of cyanobacteria in recently disturbed places, highlight the potential of these two groups of organisms to actively and more quickly restore arid ecosystems degraded by fires.