Argumento de The Role of Physical and Biological Soil Crusts on the Water Balance In Semiarid Ecosystems
Colección: Tesis doctorales ; 330
Formato: CD-ROM
In arid and semiarid areas, the interplant spaces are usually covered by physical and biological soil crusts. These crusts, though representing an almost negligible portion of the soil profile, have a number of crucial roles. Soil crusts form the boundary between soil and atmosphere and therefore control gas, water and nutrient exchange into and through soils.
Concretely, in the last decade, the study of biological soil crusts (BSCs) (complex communities of cyanobacteria, algae, fungi, lichens, mosses and other microorganisms in intimate association with soil particles) has drawn the attention of a growing number of researchers due to the key role they play in numerous processes in the ecosystems where they appear. Unlike physical crusts, BSCs protect soils against erosion by water and wind, and increase soil fertility by fixing atmospheric C and N, synthesising polysaccharides and reducing nutrient losses by runoff and erosion.
Through their influence on numerous properties that affect how water moves though soils such as roughness, porosity, hydrophobicity, cracking, and albedo, BSCs play a key role in water processes, such as infiltration and runoff, evaporation and soil moisture. It is widely known the role of physical crusts in decreasing soil porosity and hydraulic conductivity, thus decreasing infiltration. However, there is controversy regarding the role of BSCs in infiltration and runoff processes. Some studies indicate that BSCs increase infiltration, and consequently, decrease runoff, whereas others have reported that they decrease infiltration and increase runoff or that they have no effect on either of them. In addition, the influence of BSCs on other soil water balance components such as evaporation and soil moisture has hardly been studied and the scarce existing studies also show contradicting results.0
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