Acetylene reduction by cryptogamic crusts from a blackbrush community as related to resaturation and dehydration

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

doi:10.1016/0038-0717(92)90059-7

Cited by 73 publications

(43 citation statements)

References 10 publications

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“…Assuming that nitrogen fixation occurs during 12 h day −1 and during 100 day year −1 , we would estimate an annual nitrogen input of 3.5 kg ha −1 year −1 . This value is similar to those reported by Isichei (1980) for crusts of savannah regions in Nigeria and by Jeffries et al (1992) in southern Utah (USA). Our estimates of nitrogen fixation are also in the same order of magnitude as those measured in highly active coastal cyanobacterial mats ( Stal et al, 1984).…”

supporting

confidence: 92%

Nitrogen fixation by microbial crusts from desiccated Sahelian soils (Niger)

Issa¹,

Stal²,

Défarge³

et al. 2001

Soil Biology and Biochemistry

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Cyanobacterial crusts developing on the sandy and loamy soils of fallow lands in the Sahel (Niger) were investigated for their potential to fix nitrogen. Three sites were selected in this arid environment, differing in sediment type and species composition. In the sandy sites heterocystous nitrogen-fixing cyanobacteria were present, whereas the loamy site did not contain such species. All sites showed light-dependent nitrogenase activity, starting within 2 h after re-wetting of the desiccated crust samples. Inhibition of photosystem II caused a decrease of nitrogenase activity in the samples with heterocystous cyanobacteria, but was stimulatory in the non-heterocystous crust. The results suggest that cyanobacterial crusts may be important for the improvement of the soil by enriching it with nitrogen.Author Keywords: Nitrogen fixation; Cyanobacteria; Microbiotic crusts; Arid and semi-arid environments Cyanobacterial crusts in desert ecosystems fulfil a number of important functions. The filamentous cyanobacteria form tough, entangled structures that render stability to the soil surface and protect it from erosion (De Winder et al., 1989). Mucilage produced by the cyanobacteria serves as water storage ( Decho, 1990). Photosynthesis enriches the soil with organic matter, which improves its structure and biological activity ( Lange et al., 1994). Because many cyanobacteria are capable of fixing nitrogen, the soil may be enriched with nitrogen, hence serving as natural fertiliser ( Zaady et al., 1998).This investigation was carried out to demonstrate the capacity of nitrogen fixation by microbial crusts developing in the Sahel (Niger) and to relate this to species composition and sediment morphological characteristics.The samples were obtained from western Niger, between 13° 32′ N and 2° 42′ E. The climate is typical of the southern Sahel, with a single summer rainy season of 4 months and a mean annual average rain of about 560 mm. Average minimum and maximum temperatures are 22 and 34°C. Samples of the desiccated crusts were collected in 1995 from three different sites located in fields left fallow. The sites varied in their topographic and hydrological characteristics, particle size distribution, and microbial cover. Site 1 (Hama) contained microbial crusts covering 60-80% of the surface of residual sand dunes that developed on sandy loam soil material. At site 2 (Chef 2) microbial crusts covered more than 80% of the surface of a depressed zone of loamy soil material between sand dunes where water accumulated after rain events. Microbial crusts at site 3 (Mali-Djibo1) covered almost 100% of the border of a depressed zone of sandy to sandy-loam material. The microbial crusts were sampled at the beginning of the dry season and kept desiccated in the dark for 3 years until they were used for the experiments.The biological composition of the microbial crusts revealed that Porphyrosiphon kaernbachii was by far the most abundant species, but other cyanobacteria were also encountered. These included other non-hete...

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supporting

confidence: 92%

Nitrogen fixation by microbial crusts from desiccated Sahelian soils (Niger)

Issa¹,

Stal²,

Défarge³

et al. 2001

Soil Biology and Biochemistry

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“…PII: S 0 0 3 8 -0 7 1 7 ( 0 0 ) 0 0 0 0 4 -3 www.elsevier.com/locate/soilbio 1975; Eskew and Ting, 1978;Skujins, 1984;Terry and Burns, 1988;Jeeries et al, 1992;Zaady et al, 1998;Evans and Belnap, 1999). Soil crust communities, as well, have considerable photosynthetic potential, although this is limited by the hydration status (Lange et al, 1992(Lange et al, , 1998Jeeries et al, 1993) and is thus highly dependent on precipitation, i.e., rain, fog, dew and atmospheric water vapour.…”

Section: Introductionmentioning

confidence: 99%

Patterns of CO2 exchange in biological soil crusts of successional age

Zaady

Kühn

Wilske

et al. 2000

Soil Biology and Biochemistry

137

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The objective of this paper was to determine whether CO 2 exchange rates could be used as an indicator for determining the state of development and species or functional composition of biological soil crusts in dierent successional stages. We quanti®ed the CO 2 exchange rates, i.e., CO 2 assimilation and respiration, in samples from dierent microhabitats at two dierent sites in the Negev desert. In the successional pathway of the crust communities, the pioneers in colonising the soil surface are the cyanobacteria; green algae, mosses and lichens then follow. Physical in¯uences such as soil structure and types, radiation intensity, and topographic traits such as slope directions that aect water availability and soil moisture, in¯uence the successional pathways and the soil crust community. When physical conditions are the same, disturbances are key factors for a speci®c successional stage. We found a substantial gradient of CO 2 exchange at the Nizzana site for both respiration and photosynthesis. Samples from the sand dunes at the Nizzana site showed a pronounced activity gradient with high rates for assimilation (around 70 mmol CO 2 m À2 min À1) as well as respiration (60±70 mmol CO 2 m À2 min À1 ) at the base of dunes, decreasing towards the top. The soil crust samples of the Negev desert show comparable values. Hence, as ecotypes containing such biological soil crusts with dominant photosynthetically active organisms are a widespread phenomenon in desert, boreal and arctic systems, their contribution to the global cycling of trace gases and elements can be signi®cant for global budgets. 7

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“…3) If we compare the nitrogenase activity registered for Scytonema mirabile and Gloeocapsa sanguinea in Andragulla Cave with the mean value of 28.2 nmol C 2 H 4 m 22 s 21 recorded on the crusts of Scytonema sp. in semiarid areas of the USA (Jeffries et al, 1992), we find an important difference, basically owing to the fact that the latter samples had been previously rehydrated, as opposed to the limited natural moisture in the Andragulla Cave samples. This fact, along with the various experiments carried out by Renaut et al (1975), who recorded higher nitrogenase activity values if samples had been moistened prior to nitrogen fixation, confirmed the importance of a high relative humidity in the nitrogenfixation process.…”

Section: Resultsmentioning

confidence: 64%

In Situ Nitrogen Fixation by Cyanobacteria at the Andragulla Cave, Spain

Asencio¹,

Aboal²

2011

JCKS

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Andragulla Cave is 2 m high, 6 m wide, and 2 m long (deep). Its lack of depth means that it is not isolated from external influences, and the microclimate is very similar to that experienced externally. The common stress factors on the growth of cyanobacterial communities on walls inside of Andragulla Cave include excess light, dryness, lack of nutrients, and cold temperatures. Nitrogen fixation, photon flux, relative humidity, and temperature in Andragulla Cave were measured hourly over 24 hours in winter. Nitrogen fixation by the reddish-brown mat formed by both cyanobacteria Scytonema mirabile and Gloeocapsa sanguinea in cave-like environments was measured in situ for the first time by acetylene reduction. The mat-specific rates (1.6 to 7.5 nmol C 2 H 4 m 22 s 21 ) were lower compared to published values from laboratory measurements of rehydrated samples from different environments. Daytime fixation was slightly higher than nighttime fixation, where nitrogen fixation by Gloeocapsa sanguinea played an important role. The most influential parameters for environmental nitrogen fixation in Andragulla Cave were photon flux for daytime fixation, temperature for nighttime fixation, and relative humidity for both. Nitrogen fixation by cyanobacteria may be significant in these N-poor ecosystems.

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Acetylene reduction by cryptogamic crusts from a blackbrush community as related to resaturation and dehydration

Cited by 73 publications

References 10 publications

Nitrogen fixation by microbial crusts from desiccated Sahelian soils (Niger)

Nitrogen fixation by microbial crusts from desiccated Sahelian soils (Niger)

Patterns of CO2 exchange in biological soil crusts of successional age

In Situ Nitrogen Fixation by Cyanobacteria at the Andragulla Cave, Spain

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