Microenvironments and microscale productivity of cyanobacterial desert crusts

被引:228
作者
GarciaPichel, F [1 ]
Belnap, J [1 ]
机构
[1] NATL BIOL SERV,MOAB,UT 84532
关键词
cyanobacteria; deserts; extreme environments; Microcoleus vaginatus; microenvironments; Nostoc; photosynthesis; productivity; Scytonema; soil algae;
D O I
10.1111/j.0022-3646.1996.00774.x
中图分类号
Q94 [植物学];
学科分类号
071001 ;
摘要
We used microsensors to characterize physicochemical microenvironments and photosynthesis occurring immediately after water saturation in two desert soil crusts from southeastern Utah, which were formed by the cyanobacteria Microcoleus vaginatus Gomont, Nostoc spp., and Scytonema sp. The light fields within the crusts presented steep vertical gradients in magnitude and spectral composition. Near-surface light-trapping zones were formed due to the scattering nature of the sand particles, but strong light attenuation resulted in euphotic zones only ca. 1 mm deep, which were progressively enriched in longer wavelengths with depth. Rates of gross photosynthesis (3.4-9.4 mmol O-2 . m(-2). h(-1)) and dark respiration (0.81-3.1 mmol O-2 . m(-2). h(-1)) occurring within 1 to several mm from the surface were high enough to drive the formation of marked oxygen microenvironments that ranged from oxygen supersaturation to anoxia. The photosynthetic activity also resulted in localized pH values in excess of 10, 2-3 units above the soil pH. Differences in metabolic parameters and community structure between two types of crusts were consistent with a successional pattern, which could be partially explained on the basis of the microenvironments. We discuss the significance of high metabolic rates and the formation of microenvironments for the ecology of desert dusts, as well as the advantages and limitations of microsensor-based methods for crust investigation.
引用
收藏
页码:774 / 782
页数:9
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