Differential interception and evaporation of fog, dew and water vapour and elemental accumulation by lichens explain their relative abundance in a coastal desert

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• 作者：K.W. Maphangwa^a ; C.F. Musil^b ; ^{c.musil@sanbi.org.za} ; L. Raitt^c ; L. Zedda^d
• 关键词：Dew ; Fog ; Lysimeters ; Rainfall ; Ramalina sp. ; Teloschistes capensis ; Water vapour adsorption
• 刊名：Journal of Arid Environments
• 出版年：2012
• 期刊代码：93_01401963
• 类别：ear
• 出版时间：July, 2012
• 卷：82
• 期：Complete
• 页码：71-80
• 文件大小：1263 K

摘要

The interception and evaporation of fog, dew and water vapour by soils and lichens in a coastal desert were measured with automated lysimeters at hourly intervals spanning a 12 month period. Fog water and lichen thalli were chemically analysed at monthly intervals. The chemical composition of the lichens did not correspond with the elemental concentration sequence in collected fog water of oceanic origin. However, elemental concentrations were generally greater in Teloschistes capensis, whose canopy area to dry mass ratio was higher than that of Ramalina sp., indicative of a more efficient mineral absorbing thinner thallus. Non-rainfall atmospheric moisture intercepted by the bare gypsum soil was 10 times greater and that solely by the lichens up to 3 times greater than the measured rainfall amount. Water vapour contributed the highest percentage of the non-rainfall atmospheric moisture absorbed by the lichens and bare soil, followed by fog, with dew contributing the smallest percentage. T.聽capensis displayed two-fold greater interception and two-thirds less evaporation of non-rainfall atmospheric moisture than Ramalina sp. which may explain T.聽capensis 3 times greater canopy cover. Our results substantiate the crucial role of atmospheric water vapour and fog in driving lichen photosynthesis and distribution in a coastal desert.