Vapor flux induced by temperature gradient is responsible for providing liquid water to hypoliths.

Commonly comprised of cyanobacteria, algae, bacteria and fungi, hypolithic communities inhabit the underside of cobblestones and pebbles in diverse desert biomes. Notwithstanding their abundance and widespread geographic distribution and their growth in the driest regions on Earth, the source of water supporting these communities remains puzzling. Adding to the puzzle is the presence of cyanobacteria that require liquid water for net photosynthesis.

The consequences of using microlysimeters: Why microlysimeters grossly overestimate dew amounts in arid regions? A critical review.

Although commonly considered the gold standard for measurement of non-rainfall water (NRW), providing reasonable reliable data for vegetated soils, microlysimeters (MLs) tend to grossly overestimate NRW (primarily in form of dew) on barren soil. In arid and semiarid regions, the reported values may be overestimated by hundreds and even 1000 %. This bias is attributed to (i) the effect of the structure and dimension of the ML (ii) the tacit assumption that the weight difference between morning and the previous midday/evening results from dew or (iii) the belief that the MLs will provide reliable values if the difference in weight would be calculated only from the evening or night.

Interactions between biocrusts and herbaceous communities are divergent in dry and wet semiarid ecosystems.

Biocrusts are a prevalent form of living cover in worldwide drylands, and their presence are intimately associated with herbaceous community, forming a spatially mosaic distribution pattern in dryland ecosystems. The role of biocrusts as modulators of herbaceous community assembly is extensively studied, whereas, less is known whether their interactions are permanent or changeable with various environmental conditions. This study conducted a field survey of herbaceous community accompanied by three types of biocrusts (cyanobacterial, cyanobacterial-moss mixed, and moss crusts) in two contrasting (dry and wet) semiarid climate regions in the Chinese Loess Plateau, to explore whether or not climatic aridity gradient affects the interactions between biocrusts and herbaceous community.

The enigmatic enrichment of potassium and magnesium in runoff and floodwater in the Negev: Do biocrusts hold the key?

Regardless of lithology and plant cover, chemical composition of floodwater in the Negev show a consistent enrichment in K and Mg ions, which could not have been explained by the rock or clay minerals or (due to the scarcity of plants) by plant decomposition. Hypothesizing that rock-dwelling (lithobionts) or soil (loess)-dwelling biocrusts may shed light on the phenomena, we conducted sprinkling experiments in the Negev Highlands. Sprinkling was conducted on 4 types of lithobionts: cyanobacteria which inhabit the south-facing bedrock (ENC), epilithic lichens, inhabiting the inclined (EPI) and the flat (EPI) north-facing bedrocks, and endolithic lichens (ENL) inhabiting south-facing boulders.

Altitudinal Gradient and Soil Depth as Sources of Variations in Fungal Communities Revealed by Culture-Dependent and Culture-Independent Methods in the Negev Desert, Israel.

We examined fungal communities in soil profiles of 0-10 cm depth along the altitudinal gradient of 250-530-990 m.a.s.

The effect of the water source on niche partioning of chlorolichens and cyanobacteria-implications for resilience?

Microclimate determines lichens and cyanobacteria distribution in the Negev, with lichens and cyanobacteria inhabit dewy and dewless habitats, respectively. Lichens experiences more frequent and extensive environmental fluctuations than cyanobacteria. The spatial partitioning of chlorolichens (eukaryotes) and cyanobacteria (prokaryotes) are intriguing, especially following recent intense search for extraterrestrial life.

Dew and fog as possible evolutionary drivers? The expansion of crustose and fruticose lichens in the Negev is respectively mainly dictated by dew and fog.

The expansion of crustose lichens in the Negev is principally determined by dew and that of fruticose lichens by fog. Crustose and fruticose lichens are largely adapted to dew and fog, respectively. Although crustose and fruticosea lichens were shown to efficiently use dew and fog, the link between their expansion and the occurrence of dew and fog has never been shown experimentally.

Data variability or paradigm shift? Slow versus fast recovery of biological soil crusts-a review.

Biological soil crusts, known also as biocrusts, provide valuable ecosystem services, especially in arid and semiarid regions. They may affect geomorphological (stability), hydrological (infiltration, evaporation), biochemical (carbon and nitrogen fixation) and ecological (germination and growth of vascular plants) processes, and their disturbance may have important ecological consequences. The common view, as reflected in hundreds of papers, regards biocrusts as having extremely slow recovery with characteristic time of up to hundreds and even thousands of years.

Drought effect on biocrust resilience: High-speed winds result in crust burial and crust rupture and flaking.

Once established, biocrusts (known also as biological soil crusts or microbiotic crusts) are thought to be relatively resilient to wind erosion, with crust burial being considered as the main mechanism responsible for crust death. Thus far, to the best of our knowledge, crust flaking and rupture under natural conditions were not reported. We report herein a two-year study during two severe drought years (2010-2012) in a dunefield in the Negev Desert during which in addition to crust burial, crust rupture and flaking also took place.