The contribution of fog to water and nutrient supply to Arthraerua leubnitziae in the central Namib Desert, Namibia. (February 2019)

• Record Type: Journal Article
• Authors: Gottlieb, Tunehafo R.; Eckardt, Frank D.; Venter, Zander S.; Cramer, Michael D.
• Is Part Of: Journal of arid environments. Volume 161(2019)
• Page Start: 35
• Page End: 46
• Publication Date: 2019-02
• Subjects: Arthraerua leubnitziae -- Fog -- Atmospheric deposition -- Central Namib desert -- Nutrient supply; Arid regions ecology -- Periodicals; Arid regions -- Periodicals; Écologie des régions arides -- Périodiques; Régions arides -- Périodiques; 577.54
• DOI: 10.1016/j.jaridenv.2018.11.002
• Languages: English
• ISSNs: 0140-1963

Abstract

Abstract: Fog is a key source of moisture to the biota of the coastal Namib Desert and is associated with particulates that may contain essential nutrients for plants. Furthermore, fog makes dust deposited on leaves or on soil accessible for plant uptake. This study was carried out at five meteorological stations in the gravel plains of the central Namib Desert, along an east-west transect increasing in elevation inland. We hypothesised that marine-derived deposition contributes to moisture and nutrient supply of Arthraerua leubnitziae, an endemic shrub restricted to the fog zone of the central Namib Desert, and consequently determines its distribution. The range of A. leubnitziae, derived from a species distribution model, was found to coincide with areas with high fog occurrence, with fog contributing 36% to the modelled distribution of A. leubnitziae alongside precipitation (43%), isothermality (15%) and elevation (6%). We measured nutrients deposited in fog water derived from wet and dry deposition Ca 2+, K +, Mg 2+, Na +, Cl −, Br −, NO3 −, PO4 3− and SO4 2− and plant essential nutrients in plant and soil samples (N, P, K, Ca, Mg, Mn, Fe, Cu and Zn). We also determined the nutrient uptake by stems of A. leubnitziae . Over the course of the sampling cycle, the total annual nutrient content of fog and dust was dominated by Ca 2+ and Na + . Most of the nutrients (K +, Mg 2+, Na +, and SO4 2− ) were of marine origin. A. leubnitziae was found to be able to directly intercept and absorb some of the nutrients in the dust and fog via their stems. The low nutrient concentrations in the soils of the Namib Desert and significant inputs from dust and fog suggest deposition is an important source of nutrients for A. leubnitziae . We conclude that water and nutrients should not be considered separately in studying the role of fog as a determinant of plant distributions. Highlights: 92% of the moisture in the central Namib desert was contributed by fog. Fog is more than a source of water in the Namib Desert, also providing and enabling access to nutrients for A. leubnitziae . The distribution overlap of A. leubnitziae with the occurrence of fog may indicate the dependence of these plants on fog.