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| Titel |
The role of biological soil crusts on soil moisture |
| VerfasserIn |
S. Chamizo, Y. Cantón, R. Lázaro, E. Rodriguez-Caballero, F. Domingo |
| Konferenz |
EGU General Assembly 2012
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 14 (2012) |
| Datensatznummer |
250070527
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| Zusammenfassung |
| In water-limited ecosystems, water becomes the most important driver for plant
productivity. In these systems, spatial distribution of water resources is not random but
organized into a mosaic of water-depletion areas linked to water-accumulation
areas. In other words, water is transferred from interplant patches that act as source
areas to vegetation patches that act as sinks of this resource. Thus, structure and
functioning of interplant patches have a decisive role in water redistribution and
distribution patterns of vegetation. Soil surface in the interplant spaces of most
arid and semiarid ecosystems is covered by biological soil crusts (BSCs). These
organisms regulate water fluxes into and through soils and play major roles in local
hydrological processes. In the last years, the role of these organisms in infiltration
and runoff has gained increased importance and a better knowledge about their
effects on these processes has been acquired. However, the role of BSCs in other
important components of the water balance such as evaporation or soil moisture has
been scarcely studied, so that their effects on these processes remain unknown.
The objective of this work is to examine the influence of BSCs on soil moisture
regimes in the top profile of the soil in two semiarid ecosystems of SE Spain with
contrasting soil texture and where BSCs are well-represented. Soil moisture content at
0.03 and 0.10 m was monitored under two representative types of BSCs, a dark
cyanobacteria-dominated BSC and a light-coloured lichen-dominated BSC, and in
soils where these BSCs were removed by scraping, at both study sites. Our results
show that, under high water conditions, removal of BSCs leads to a decrease in
soil moisture compared to soils covered by BSCs. Decrease in soil moisture due
to BSC removal namely affects moisture in the upper layer of the soil (0.03 m),
but has little impact in deeper soil (0.10 m). Evaporation is also generally faster
in soils with no BSCs than in soils covered by them. The type of BSC influences
soil moisture in a different way depending on soil water conditions. Under high
water content conditions, soil water loss is faster and soil moisture content lower
under cyanobacterial than under lichen BSCs, due to higher infiltration promoted by
lichens. On the contrary, under low water content conditions, lichen-crusted soils dry
out faster and exhibit less moisture than cyanobacteria-crusted ones, attributed
to the larger porosity and subsequent greater evaporative losses in lichen- than in
cyanobacteria-crusted soils. We found higher moisture in coarse-textured soils than in
fine-textured ones, despite the higher water retention capacity of the latter soils. More
favourable conditions in the coarser soils, which had greater organic matter content,
aggregate stability and were subject to less water stress due to its proximity to the
coast, seems to contribute to this increased soil moisture content. BSCs therefore
play an important role on the maintenance of water availability in the interplant
spaces, thereby strongly affecting soil physical and biological processes, and the
potential for emergence establishment and survival of plants in semiarid ecosystems. |
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