Changes in Precipitation Patterns: Responses and Strategies from Streambed Sediment and Soil Microbes
Giulia Gionchetta, Aline Frossard, Luis Bañeras and Anna Maria Romaní
from: Climate Change and Microbial Ecology: Current Research and Future Trends (Second Edition) (Edited by: Jürgen Marxsen). Caister Academic Press, U.K. (2020) Pages: 391-420.
Sediments in intermittent watersheds as well as soil systems, especially in arid and semi-arid regions, suffer an increasing pressure of drought events and water scarcity, affecting the ecosystems and the microorganisms inhabiting them. Such microbial communities contribute greatly to global biogeochemical cycles and thus it is crucial to understand their response mechanisms to increasing dryness. Microorganisms show responses to drought at different organizational levels, from the cell (e.g. spores formation, osmolytes production, cell wall thickening) to the whole community (e.g. production of extracellular polymeric substances, community composition changes). At the same time, dryness induces functional modifications such as changes in microbial respiration and organic matter degradation capabilities in both streambed sediments and soils. Water content is a major contributor to the observed responses and is highly associated to the soil/sediment water holding capacity as well as to the water solutes concentration. Knowledge from studies on microbes inhabiting extreme habitats, like deserts and hypersaline arid zones, further stress the importance of minimal water inputs (e.g. fog, dew or light rains) to support the microbial functions. Conservation of habitat heterogeneity, with diverse water holding capacities, might support the microbial resistance and resilience against the intensification of dry-wet extreme episodes, as suggested by recent studies in the field. Moreover, space heterogeneity, including arid and semiarid systems, and tight bacterial networks at highest level will significantly contribute to ecosystem fitness in about-to-come climate scenarios read more ...