The likelihood of dew to provide water to cyanobacteria (CB) and crustose lichens (CL) on soil is a matter of great controversy. Although vapour condensation takes place on cobbles of the Negev Highlands, facilitating lush cover of CL, controversy exists regarding the possible contribution of dew to CB and CL inhabiting the loessial soil of the Negev Highlands. To evaluate this matter, temperature, and measurements of the nonrainfall water (NRW) were conducted during the dewy season (August–November 2019). They included periodical NRW measurements using cloths attached to the (a) soil surface, (b) on top of 10 × 10 × 5‐ to 6‐cm cobbles, and (c) on 10 × 10 × 0.2‐cm glass plates (the cloth‐plate method, CPM). Additionally, temperature measurements took place at the soil and the cobble surfaces and in the air at 10‐cm height above ground. Air temperature and the relative humidity measured by an adjacent meteorological station facilitated the calculation of the dew‐point temperature (Td). Taking the CPM as reference, 24 mornings with NRW ≥0.03 mm (the threshold of lichen metabolism) were recorded. Vapour condensation, that is, NRW ≥0.1 mm were recorded during 16 mornings on the cobbles (with a maximum of 0.21 mm) but never on the soil, where maximum NRW reached only 0.023 mm. Surface temperature never reached Td. We therefore conclude that unlike lithic lichens that inhabit bedrocks and cobbles in the Negev Highlands, dew cannot be regarded as a meaningful direct source of water for CB or CL biocrusts on soil.

中文翻译：

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评估土壤表面凝结蒸气的可能性：内盖夫经验

露水为土壤中的蓝细菌（CB）和甲壳类地衣（CL）提供水的可能性引起很大争议。尽管在内盖夫高地的鹅卵石上发生了蒸汽凝结，有利于CL的茂密覆盖，但关于露水对内盖夫高地的黄土土壤中CB和CL的可能贡献存在争议。为了评估此问题，在露水季节（2019年8月至11月）进行了温度和非降雨水（NRW）的测量。他们包括使用（a）土壤表面，（b）10×10×5至6 cm鹅卵石顶部和（c）10×10×0.2 cm的玻璃板上附着的布定期进行NRW测量。布板法（CPM）。此外，在土壤和鹅卵石表面以及距地面10 cm高度的空气中进行温度测量。相邻气象站测量的气温和相对湿度有助于计算露点温度（Td）。以CPM为参考，记录了NRW≥0.03 mm（地衣代谢阈值）的24个早晨。16天早晨，在鹅卵石上记录到蒸汽凝结，即NRW≥0.1 mm（最大为0.21 mm），但从未在土壤上记录到蒸汽，最大NRW仅为0.023 mm。表面温度从未达到Td。因此，我们得出的结论是，与在内盖夫高地的基岩和卵石中居住的石质地衣不同，露水不能被视为土壤中CB或CL生物结皮的有意义的直接水源。记录NRW≥0.03 mm（地衣代谢阈值）的24个早晨。16天早晨，在鹅卵石上记录到蒸汽凝结，即NRW≥0.1 mm（最大为0.21 mm），但从未在土壤上记录到蒸汽，最大NRW仅为0.023 mm。表面温度从未达到Td。因此，我们得出的结论是，与在内盖夫高地的基岩和卵石中居住的石质地衣不同，露水不能被视为土壤中CB或CL生物结皮的有意义的直接水源。记录NRW≥0.03 mm（地衣代谢阈值）的24个早晨。16天早晨，在鹅卵石上记录到蒸汽凝结，即NRW≥0.1 mm（最大为0.21 mm），但从未在土壤上记录到蒸汽，最大NRW仅为0.023 mm。表面温度从未达到Td。因此，我们得出的结论是，与在内盖夫高地的基岩和卵石中居住的石质地衣不同，露水不能被视为土壤中CB或CL生物结皮的有意义的直接水源。