Microclimatic boundary conditions for activity of soil lichen crusts in sand dunes of the north-western Negev desert, Israel

Veste, Maik; Littmann, Thomas; Friedrich, Hartmut; Breckle, Siegmar-Walter

doi:10.1016/s0367-2530(17)30088-9

Cited by 57 publications

(48 citation statements)

References 28 publications

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“…Contrarily, the photosynthesis metabolism of green-algae and green algae soil lichens as well as of dry Microcoleus sociatus is reactivated solely by hydration in equilibrium with high air humidity (Lange et al, 1994;Lange, 2001). Lange et al (1992) and Veste et al (2001) estimated that BSCs are photosynthetically active at precipitation amounts > 0.1 mm, which is similar to the dewfall amounts reported in our field experiment (Fig. 2).…”

Section: Discussionsupporting

confidence: 86%

“…At the same time, availability of water to vascular plants largely depends on the form of precipitation: Rain infiltrating into the rooting zone of the soil supplies available water, while dew accumulating on leaves is -with few exceptions of desert succulents -not available to the plant metabolism. Dew has further been identified to be one of the major sources of BSC and lichen water supply under arid and semi-arid conditions (Kidron, 2000;Veste et al, 2001;Veste and Littmann, 2006). Hence, BSCs would benefit from repartitioning rain and from collecting dew.…”

Section: Introductionmentioning

confidence: 99%

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Dew formation on the surface of biological soil crusts in central European sand ecosystems

et al. 2012

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Abstract. Dew formation was investigated in three developmental stages of biological soil crusts (BSC), which were collected along a catena of an inland dune and in the initial substrate. The Penman equation, which was developed for saturated surfaces, was modified for unsaturated surfaces and used for prediction of dewfall rates. The levels of surface saturation required for this approach were predicted using the water retention functions and the thicknesses of the BSCs. During a first field campaign (2-3 August 2011), dewfall increased from 0.042 kg m −2 for the initial sandy substrate to 0.058, 0.143 and 0.178 kg m −2 for crusts 1 to 3, respectively. During a second field campaign (17-18 August 2011), where dew formation was recorded in 1.5 to 2.75-h intervals after installation at 21:30 CEST, dewfall increased from 0.011 kg m −2 for the initial sandy substrate to 0.013, 0.028 and 0.055 kg m −2 for crusts 1 to 3, respectively. Dewfall rates remained on low levels for the substrate and for crust 1, and decreased overnight for crusts 2 and 3 (with crust 3 > crust 2 > crust 1 throughout the campaign). Dew formation was well reflected by the model response. The suggested mechanism of dew formation involves a delay in water saturation in near-surface soil pores and extracellular polymeric substances (EPS) where the crusts were thicker and where the water capacity was high, resulting in elevated vapor flux towards the surface. The results also indicate that the amount of dewfall was too low to saturate the BSCs and to observe water flow into deeper soil. Analysis of the soil water retention curves revealed that, despite the sandy mineral matrix, moist crusts clogged by swollen EPS pores exhibited a claylike behavior. It is hypothesized that BSCs gain double benefit from suppressing their competitors by runoff generation and from improving their water supply by dew collection. Despite higher amounts of dew, the water availability to the crust community decreases with crust development, which may be compensated by ecophysiological adaptation of crust organisms, and which may further suppress higher vegetation or mosses.

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Section: Discussionsupporting

confidence: 86%

Section: Introductionmentioning

confidence: 99%

Dew formation on the surface of biological soil crusts in central European sand ecosystems

et al. 2012

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“…Notably, there are large differences in the reported rates of activation of photosynthesis after rehydration (Scherer et al, 1984;Green et al, 1994;Dodds et al, 1995;Garcia-Pichel and Belnap, 1996;Mazor et al, 1996;Veste et al, 2001;Satoh et al, 2002). Studies by Potts (1994) and our own (data not shown) clearly indicated that the duration of desiccation was an important factor; the shorter the dry phase the faster was the activation of photosynthetic capability.…”

Section: Activation Of Psii During Rehydrationmentioning

confidence: 66%

“…It was concluded that stabilization of existing proteins during dehydration must be involved to ensure rapid reappearance of growth of Nostoc under favorable conditions. Very little is known about the mechanisms whereby the cyanobacteria in the crusts activate the photosynthetic system upon rehydration Tarnawski et al, 1994;Dodds et al, 1995;Garcia-Pichel and Belnap, 1996;Lü ttge et al, 1996;Qiu and Gao, 2001;Veste et al, 2001) and protect themselves against photoinhibition under the high light intensities particularly during periods of declining water content. Coordination of light energy flux transfer with the rate of electron transport and CO 2 fixation is therefore of particular importance during periods of hydration and dehydration.…”

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confidence: 99%

Activation of Photosynthesis and Resistance to Photoinhibition in Cyanobacteria within Biological Desert Crust

2004

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Filamentous cyanobacteria are the main primary producers in biological desert sand crusts. The cells are exposed to extreme environmental conditions including temperature, light, and diurnal desiccation/rehydration cycles. We have studied the kinetics of activation of photosynthesis during rehydration of the cyanobacteria, primarily Microcoleus sp., within crust samples collected in the Negev desert, Israel. We also investigated their susceptibility to photoinhibition. Activation of the photosynthetic apparatus, measured by fluorescence kinetics, thermoluminescence, and low temperature fluorescence emission spectra, did not require de novo protein synthesis. Over 50% of the photosystem II (PSII) activity, assembled phycobilisomes, and photosystem I (PSI) antennae were detected within less than 5 min of rehydration. Energy transfer to PSII and PSI by the respective antennae was fully established within 10 to 20 min of rehydration. The activation of a fraction of PSII population (about 20%-30%) was light and temperature-dependent but did not require electron flow to plastoquinone [was not inhibited by 3-(3,4-dichlorophenyl)-1,1-dimethylurea]. The cyanobacteria within the crusts are remarkably resistant to photoinhibition even in the absence of protein synthesis. The rate of PSII repair increased with light intensity and with time of exposure. Consequently, the extent of photoinhibition in high-light-exposed crusts reached a constant, relatively low, level. This is in contrast to model organisms such as Synechocystis sp. strain PCC 6803 where PSII activity declined continuously over the entire exposure to high illumination. Ability of the crust's organisms to rapidly activate photosynthesis upon rehydration and withstand photoinhibition under high light intensity may partly explain their ability to survive in this ecosystem.Biological sand crusts are found in many deserts around the world. They play an important role in stabilizing sandy areas and affect the vegetation composition (Prasse and Bornkamm, 2000;Hagen, 2001;Abed et al., 2002;Eldridge and Leys, 2003;Rajot et al., 2003). Their destruction by man-made activities such as overgrazing is considered an important promoter of desertification in arid and semiarid regions. The crusts are formed by adhesion of the sand to extracellular polysaccharides excreted mainly by filamentous cyanobacteria. These cyanobacteria are the main primary producers in arid desert crusts; other microorganisms including fungi, microalgae, and bacteria are also abundant, particularly in humid areas often covered by a thick crust . The microorganisms inhabiting the crusts are exposed to extreme environmental conditions including high daytime temperatures during the summer, low temperatures during the night in the winter, high radiation including visible and UV light, and frequent hydration/ dehydration cycles.To cope with the harsh conditions in the biological crusts the organisms must have developed survival mechanisms, the nature of which remains largely unknown. Crucial for survival i...

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“…For instance, a rainfall gradient of 200-250 mm exists from the coastal region to the arid core of the Negev Desert, Israel. Dew precipitation accounts on average for 33 mm or 25-30% of the annual precipitation in the gravel desert of the Negev highlands (Evenari, 1981), and it was concluded that dew and fog play a particular role for BSC activity (e.g., Lange et al, 1994;Veste et al, 2001). However, significant differences exist in the amount of dew on a medium spatial scale (Kidron, 2000), so that dew and fog increase by 0.03 mm per 100 m increase in elevation from the coastal lowlands to the highlands of the Negev (Kidron, 1999).…”

Section: Introductionmentioning

confidence: 99%

The CO<sub>2</sub> exchange of biological soil crusts in a semiarid grass-shrubland at the northern transition zone of the Negev desert, Israel

et al. 2008

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Abstract. Biological soil crusts (BSC) contribute significantly to the soil surface cover in many dryland ecosystems. A mixed type of BSC, which consists of cyanobacteria, mosses and cyanolichens, constitutes more than 60% of ground cover in the semiarid grass-shrub steppe at Sayeret Shaked in the northern Negev Desert, Israel. This study aimed at parameterizing the carbon sink capacity of welldeveloped BSC in undisturbed steppe systems. Mobile enclosures on permanent soil borne collars were used to investigate BSC-related CO 2 fluxes in situ and with natural moisture supply during 10 two-day field campaigns within seven months from fall 2001 to summer 2002. Highest BSC-related CO 2 deposition between -11.31 and -17.56 mmol m −2 per 15 h was found with BSC activated from rain and dew during the peak of the winter rain season. Net CO 2 deposition by BSC was calculated to compensate 120%, -26%, and less than 3% of the concurrent soil CO

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Microclimatic boundary conditions for activity of soil lichen crusts in sand dunes of the north-western Negev desert, Israel

Cited by 57 publications

References 28 publications

Dew formation on the surface of biological soil crusts in central European sand ecosystems

Dew formation on the surface of biological soil crusts in central European sand ecosystems

Activation of Photosynthesis and Resistance to Photoinhibition in Cyanobacteria within Biological Desert Crust

The CO<sub>2</sub> exchange of biological soil crusts in a semiarid grass-shrubland at the northern transition zone of the Negev desert, Israel

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Microclimatic boundary conditions for activity of soil lichen crusts in sand dunes of the north-western Negev desert, Israel

Cited by 57 publications

References 28 publications

Dew formation on the surface of biological soil crusts in central European sand ecosystems

Dew formation on the surface of biological soil crusts in central European sand ecosystems

Activation of Photosynthesis and Resistance to Photoinhibition in Cyanobacteria within Biological Desert Crust

The CO&lt;sub&gt;2&lt;/sub&gt; exchange of biological soil crusts in a semiarid grass-shrubland at the northern transition zone of the Negev desert, Israel

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The CO<sub>2</sub> exchange of biological soil crusts in a semiarid grass-shrubland at the northern transition zone of the Negev desert, Israel