Ecohydrological interactions within "fairy circles" in the Namib Desert: Revisiting the self‐organization hypothesis. Issue 2 (18th February 2017)

• Record Type: Journal Article
• Authors: Ravi, Sujith; Wang, Lixin; Kaseke, Kudzai Farai; Buynevich, Ilya V.; Marais, Eugene
• Is Part Of: Journal of geophysical research. Volume 122:Issue 2(2017)
• Page Start: 405
• Page End: 414
• Publication Date: 2017-02-18
• Subjects: Aeolian -- vegetation patterns -- plant‐soil feedbacks -- infiltration -- runoff -- soil moisture; Geobiology -- Periodicals; Biogeochemistry -- Periodicals; Biotic communities -- Periodicals; Geophysics -- Periodicals; 577.14
• DOI: 10.1002/2016JG003604
• Languages: English
• ISSNs: 2169-8953

Abstract

Abstract: Vegetation patterns such as rings, bands, and spots are recurrent characteristics of resource‐limited arid and semiarid ecosystems. One of the most recognizable vegetation patterns is the millions of circular patches, often referred to as "fairy circles, " within the arid grassland matrix extending over hundreds of kilometers in the Namib Desert. Several modeling studies have highlighted the role of plant‐soil interactions in the formation of these fairy circles. However, little is known about the spatial and temporal variabilities of hydrological processes inside a fairy circle. In particular, a detailed field assessment of hydrological and soil properties inside and outside the fairy circles is limited. We conducted extensive measurements of infiltration rate, soil moisture, grass biometric, and sediment grain‐size distribution from multiple circles and interspaces in the Namib Desert. Our results indicate that considerable heterogeneity in hydrological processes exists within the fairy circles, resulting from the presence of coarser particles in the inner bare soil areas, whereas concentration of fine soil occurs on the vegetated edges. The trapping of aeolian and water‐borne sediments by plants may result in the observed soil textural changes beneath the vegetation, which in turn, explains the heterogeneity in hydrological processes such as infiltration and runoff. Our investigation provides new insights and experimental data on the ecohydrological processes associated with fairy circles, from a less studied location devoid of sand termite activity within the circles. The results seem to provide support to the "self‐organization hypothesis" of fairy circle formation attributed to the antiphase spatial biomass‐water distributions. Key Points: We provide experimental evidence for the ecohydrological interactions within fairy circles in the Namib Desert Considerable heterogeneity in hydrological processes and soil properties exists between the gaps and edges of fairy circles Our results support the self‐organization hypothesis of fairy circle formation attributed to scale‐dependent antiphase biomass‐water feedbacks