CO<sub>2</sub> fluxes of cryptogamic crusts

Jeffries, Douglas L.; Link, Steven O.; Klopatek, Jeffrey M.

doi:10.1111/j.1469-8137.1993.tb03891.x

Cited by 28 publications

(11 citation statements)

References 19 publications

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“…Instantaneous rates of carbon (C; Garcia-Pichel and Belnap 1996;Evans and Lange 2001;Jeffries et al 1993) and nitrogen (Johnson et al 2005;Abed et al 2010) fixation in BSCs during periods of microbial activity are high enough to expect noticeable long-term increases in BSC soil C and N content. However, biomass does not seem to accumulate in a commensurate manner in BSCs during succession to maturity, and loss processes are deemed to be important (Garcia-Pichel and Belnap 1996).…”

Section: Introductionmentioning

confidence: 99%

Nitrogen cycling in desert biological soil crusts across biogeographic regions in the Southwestern United States

2011

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Biological soil crusts (BSCs) are thought to be important in the fertility of arid lands as gateways for carbon (C) and nitrogen (N). Studies on the Colorado Plateau have shown that an incomplete internal N cycle operates in BSCs that results in significant exports of dissolved organic N, ammonia and nitrate into the bulk soil through percolating water, thus mechanistically explaining their role as a N gateway. It is not known if this pattern is found in other arid regions. To examine this, we measured rates of major biogeochemical N-transformations in a variety of BSCs collected from the Colorado Plateau and the Mojave, Sonoran and Chihuahuan Deserts. Dinitrogen fixation and aerobic ammonia oxidation were prominent transformations at all sites. We found anaerobic ammonia oxidation (anammox) rates to be below the detection limit in all cases, and at least 50-fold smaller than rates of N 2 -fixation, making it an irrelevant process for these BSCs. Heterotrophic denitrification was also of little consequence for the flow of N, with rates at least an order of magnitude smaller than those of N 2 -fixation. Thus we could confirm that despite the demonstrable differences in microbial community composition and soil material, BSCs from major biogeographic regions in arid North America displayed a remarkably consistent pattern of internal N cycling. The implications for arid land fertility drawn from previous studies in the Colorado Plateau appear applicable to BSCs across other arid regions of the Southwestern United States.

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Section: Introductionmentioning

confidence: 99%

Nitrogen cycling in desert biological soil crusts across biogeographic regions in the Southwestern United States

2011

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“…Such a phenomenon can also be observed in the field, where the greening occurs after long rainy and cloudy conditions. In these environments, the water potential obviously plays a key role in the control of growth and activity of microorganisms [3,6,15]. Recently, we have shown that cyanobacteria in desert soils can track water, suggesting that cyanobacterial migration was controlled by the water content [11].…”

Section: Introductionmentioning

confidence: 99%

Hydrotaxis of Cyanobacteria in Desert Crusts

Pringault¹,

García-Pichel

2003

Microb Ecol

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We studied the migration of cyanobacteria in desert crusts from Las Bárdenas Reales (Spain). The crusts were almost exclusively colonized by the filamentous cyanobacterium Oscillatoria, which formed a dense layer approximately 600 lm thick located between 1.5 and 2.1 mm deep. Laboratory and field experiments showed that saturation of the crust with liquid water induced a migration of the cyanobacteria leading to a significant greening of the surface within a few minutes. Under light and rapid evaporation, the green color rapidly disappeared and the crust surface was completely devoid of filaments within 60 min. In contrast, 260 min was required to recover the original white color of the crust when slow evaporation was experimentally imposed. The up and down migration following wetting and drying occurred also in the dark. This demonstrates that light was not a required stimulus. Addition of ATP synthesis inhibitors prevented the cyanobacterium from migrating down into the crust, with filaments remaining on the surface. Therefore, the disappearance of the green color observed during desiccation can only be attributed to an active cyanobacterial motility response to the decrease in the water content. The simplest explanation that can account for the evidence gathered is the presence of a mechanism that links, directly or indirectly, these motility responses to gradients in water content, namely a form of hydrotaxis.

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“…Most of the studies [22][23][24][25] have focused mainly on structure, distribution, nitrogen fixation or work with isolated cultures. Despite their importance only a few studies are interested in the ecophysiology of cyanobacterial crust communities of the tropical and subtropical inselberg rock surfaces [7,9,19,21,[26][27][28] and seasonally inundated system of plans and dunes [29,30]. Most studies deal with the photosynthesis of the cryptogamic crusts under laboratory conditions [29] while only few characterize the photosynthesis of free-living cyanobacteria under natural conditions in the tropical field [7,21,28,31] and desert [11,13,30].…”

Section: Introductionmentioning

confidence: 99%

Ecophysiological responses of desiccation-tolerant cryptobiotic crusts

et al. 2011

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In our present studies, the recovery of photosynthetic activity after rehydration was demonstrated. We measured chlorophyll fluorescence, CO2 gas exchange and the pigment composition in the previously long-term air-dried cryptogamic inselberg crusts collected from two tropical areas. The cryptobiotic crusts were collected from different localities on similar ecological and climatic conditions from extreme habitats of inselbergs (outcrops). These inselbergs are characterized by a dry microclimate and are covered by scarce soil. We found that the ecophysiological responses of both cryptogamic inselberg crusts showed an extremely high degree of desiccation-tolerance due to the fast and full recovery during rehydration. The photosynthetic activity of the cryptobiotic crusts were restored and regained within 15 and 40 min, respectively, after rehydration. Photosynthetic activity of the crusts was retained at all applied light intensities when enough water was available, however the degree of the recovery was different between the crusts. Photosynthetic pigment contents were strongly and positively correlated with water content. Our results indicated that tropical desiccation-tolerant cryptogamic crusts found on inselberg rock surfaces have CO2 fixation ability in the range of cyanobacteria and lichens, suggesting that at a global scale they can assimilate CO2 in a significant amount.

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CO₂ fluxes of cryptogamic crusts

Cited by 28 publications

References 19 publications

Nitrogen cycling in desert biological soil crusts across biogeographic regions in the Southwestern United States

Nitrogen cycling in desert biological soil crusts across biogeographic regions in the Southwestern United States

Hydrotaxis of Cyanobacteria in Desert Crusts

Ecophysiological responses of desiccation-tolerant cryptobiotic crusts

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CO2 fluxes of cryptogamic crusts

Cited by 28 publications

References 19 publications

Nitrogen cycling in desert biological soil crusts across biogeographic regions in the Southwestern United States

Nitrogen cycling in desert biological soil crusts across biogeographic regions in the Southwestern United States

Hydrotaxis of Cyanobacteria in Desert Crusts

Ecophysiological responses of desiccation-tolerant cryptobiotic crusts

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CO₂ fluxes of cryptogamic crusts