期刊
SOIL SCIENCE SOCIETY OF AMERICA JOURNAL
卷 76, 期 5, 页码 1685-1695出版社
SOIL SCI SOC AMER
DOI: 10.2136/sssaj2012.0021
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资金
- Bureau of Land Management [FAA080005]
- UNLV Urban Sustainability Initiative Fellowship Program [DOE DE-FG02-08ER64709, DOE DE-EE-0000716]
- NSF-Nevada EPSCor, SEPHAS Fellowship Program (NSF-EPSCor RING-TRUE III) [0447416]
- NASA-EPSCoR [NSHE 08-55]
- Farouk El-Baz Student Research Grant Program
- Geological Society of America Student Grant Program
- ExxonMobil Student Research Grant Program
- UNLV Geoscience Scholarship Program
- Bernada French Scholarship
- UNLV Adams/GPSA Scholarship
Biological soil crusts (BSCs) are bio-sedimentary complexes that play critical ecological roles in arid landscapes; however, the interactions between component biota and sediments are poorly understood. A detailed micromorphological investigation of BSC development and crust microstructure in the Muddy Mountains Wilderness Area, Nevada, examined features in thin section using petrographic microscopy, light microscopy, scanning electron microscopy, and energy dispersive x-ray spectroscopy. The >1800 microscopic observations were linked to crust macroscale features and soil geomorphology. Complex bio-sedimentary structures of BSCs reflect a dynamic genetic history and diverse formative processes, including: (i) stabilization and authigenic mineral precipitation; (ii) wetting-drying and expansion-contraction; (iii) dust capture; (iv) microscale mass wasting; and (v) vesicular (Av) horizon formation. A new conceptual model for hot deserts illustrates how these processes co-develop with BSC succession, during countless wet-dry cycles, to build up pinnacle microtopography while simultaneously forming Av horizons in the bio-rich and bio-poor zones. Complex surficial and internal bio-sedimentary structures, which vary as a function of crust morphology, trap surface water for uptake by crust organisms, while dust influx provides a source of nutrients. These phenomena influence landscape-scale water dynamics and biogeochemical cycling, increasing the availability of soil resources during times of biotic stress. Biological soil crusts uniquely facilitate the accumulation, morphology, and ecosystem function of dust and should, therefore, be considered critical agents in arid pedogenesis and landscape development.
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