Alga- and Lichen-Stabilized Surface Crusts as Soil Nitrogen Sources

Shields, Lora Mangum; Mitchell, Charles E.; Drouet, Francis

doi:10.2307/2438917

Cited by 52 publications

(14 citation statements)

References 9 publications

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“…As they require a stable substrate on which to develop, stabilization of the surface by algal filaments is a precursor to their development. The growth of lichens results in marked increases in the capability for nitrogen fixation (Shields et al 1957;Rogers et al 1966;Rogers and Lange 1971;Rogers 1974). Where a strong grass canopy develops, overtopping and competition for sunlight, moisture and nutrients, and possible allelopathic effects of litter may lead to reductions in non-vascular cover.…”

Section: Microbiota and Ecosystem Processesmentioning

confidence: 99%

Microbiotic soil crusts - a review of their roles in soil and ecological processes in the rangelands of Australia

Eldridge¹,

Greene²

1994

Soil Res.

500

307

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Microbiotic crusts are assemblages of non-vascular plants (mosses, liverworts, algae, lichens, fungi, bacteria and cyanobacteria) which form intimate associations with surface soils. They play a major role in infiltration processes through changes to soil physico-chemical properties, and through their influence on soil surface roughness. Whilst some research suggests that they may restrict infiltration, Australian experience is that they are generally associated with enhanced infiltration. Unlike physical soil crusts, microbiotic crusts stabilize the soil against water and wind erosion, increasing landscape stability, particularly in areas of low vascular plant cover. Microbiotic crusts are thus useful indicators of soil surface condition, and cyanobacteria in the crusts fix nitrogen which may be utilized by developing vascular plant seedlings. Little is known, however, about how they interact with vascular plants and soil invertebrates. Their role in rangeland ecosystems has received renewed attention over the past few years with an increasing interest in ecologically sustainable development of arid and semi-arid grazing systems.In this review we discuss the characteristics and distribution of microbiotic crusts in the rangelands of Australia, their roles in soil and eco!ogical processes and the impacts of fire and grazing. Finally we propose a new system for classifying crusts into functional groups and identify areas requiring further investigation.

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Section: Microbiota and Ecosystem Processesmentioning

confidence: 99%

Microbiotic soil crusts - a review of their roles in soil and ecological processes in the rangelands of Australia

Eldridge¹,

Greene²

1994

Soil Res.

500

307

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“…The blue-green algae are reported to be highly resistant to desiccation (Shields, Mitchel & Drouet, 1957;Henrikson & Simu, 1971;Fogg et al, 1973;Brock, 1975), and several blue-green algae have been revived after long-term dehydration (Bristol, 1919;Lipman, 1941). Although growth resumes quickly after wetting, moisture is usually the liiniting factor in development of crusts (Shields & Durrell, 1964;Fogg et al, 1973;West & Skujins, 1977), and temperature may become limiting during the wet spring (Rychert & Skujins, 1974).…”

Section: Introductionmentioning

confidence: 99%

CO₂ fluxes of cryptogamic crusts

1993

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SUMMARYTlie carbon dioxide exchange of Mkrocoleus-and Scytonema-dom'mated cryptogamic crusts as related to dehydration was measured in the laboratory with a modified discrete sampling technique and infrared gas analysis. The dehydration curves predicted that carboxylation and dark respiration rates for both crust types would become zero at from 4 to 5 % water content (W) (approximately 16-23 % soil saturation), with the water contents at which the rates became zero significantly lower in the second treatment cycle than the first. The dehydration curves predicted that net photosynthesis rates would become zero at 6-7-11-2 "^ W (27-44 °' o soil saturation), with the water contents at which the rates became zero significantly higher in the second cycle of treatment than the first.

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“…In particular, cyanobacteria and cyanobacterial symbioses were recognized as important nitrogen sources in marine environments (Dugdale et al , 1959(Dugdale et al , , 1961Goering et al, 1966;Stewart, 1965), in lakes and deserts (Tchan and Beadle, 1955), in volcanic areas (Fogg, 1947;Shields et al, 1957), and in the rather bleak expanses of Antarctica (Brightman, 1959). Work with cyanobacteria in rice fields showed that remarkable increases in nitrogen could be obtained largely through the activity of cyanobacteria (Fogg, 1947;Allen and Arnon, 1955;Singh, 1942Singh, , 1961Stewart, 1966).…”

Section: Expansion Of Ecological U Nderstandingmentioning

confidence: 99%

Consumption of Atmospheric Nitrogen

Benson

1985

Bacteria in Nature

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Alga- and Lichen-Stabilized Surface Crusts as Soil Nitrogen Sources

Cited by 52 publications

References 9 publications

Microbiotic soil crusts - a review of their roles in soil and ecological processes in the rangelands of Australia

Microbiotic soil crusts - a review of their roles in soil and ecological processes in the rangelands of Australia

CO₂ fluxes of cryptogamic crusts

Consumption of Atmospheric Nitrogen

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Alga- and Lichen-Stabilized Surface Crusts as Soil Nitrogen Sources

Cited by 52 publications

References 9 publications

Microbiotic soil crusts - a review of their roles in soil and ecological processes in the rangelands of Australia

Microbiotic soil crusts - a review of their roles in soil and ecological processes in the rangelands of Australia

CO2 fluxes of cryptogamic crusts

Consumption of Atmospheric Nitrogen

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CO₂ fluxes of cryptogamic crusts