Research Interests

- Remotely Sensed Pattern Analysis - Spatial Statistics - Application of Unmanned Aerial Vehicles (UAV) - Forest Ecology - Biodiversity Research - Nature Conservation - Dryland Research - Self-Organization of Vegetation Google Scholar Profile

New research results on the origin of Namibia's fairy circles
		Getzin, S., Holch, S., Yizhaq, H. & Wiegand, K. (2022) Plant water stress, not termite herbivory, causes Namibia’s fairy circles. Perspectives in Plant Ecology, Evolution and Systematics, 57, 125698.
		Getzin, S. & Yizhaq, H. (Preprint) Long and undamaged roots of dying grasses in Namibian fairy circles reject the sand termite hypothesis – Response to Jürgens & Gröngröft (2023). Available at SSRN https://ssrn.com/abstract=4507988

With our new publication “Plant water stress, not termite herbivory, causes Namibia’s fairy circles” we summarize the results of extensive fieldwork undertaken in the Namib during the rainy seasons 2020 to 2022. Our continuous soil-moisture recordings in and around fairy circles indicate that the vital matrix grasses outside of the circles strongly pulled the soil water from the interior of the fairy circles. The quick death of the germinating grasses inside the fairy circles in several regions of the Namib is thus due to plant water stress and desiccation. The large and competitively superior grasses around the circles thereby actively engineer the vegetation gaps and benefit from these additional water reservoirs via long-distance diffusion of soil water.

This self-organization of the grasses is supported by the very high water conductivity of the coarse-grained sand of the fairy circles, because at a soil water content of more than 8% of the soil volume, the soil physical conditions allow the water to be sucked out of the fairy circle. Our published measurement data from 20 cm depth in the fairy circle show that soil moisture always ranged from about 9% to 13% seven to fourteen days after typical rainfall events (see Table 3). Thus, purely in terms of soil physics, a very high water conductivity to the outside to the grasses is given, which is further enhanced by the active suction of water via the grass roots and the accompanying concentration gradient in soil moisture. In particular, the perennial, rapidly greening large grasses around the periphery of the fairy circles suck up water strongly because of their competitive advantage. This causes rapid drying of the uppermost soil layer after ten to twenty days, where the young grasses die with their 10 cm long roots in the fairy circle. Our measurement data using a mobile soil moisture sensor show that the top 10 cm to 20 cm of soil on the dead grasses is significantly drier than the soil moisture measured at the same time at a depth of exactly 20 cm. This is further evidence that the young, newly established grasses in the fairy circle are dying due to desiccation in the uppermost soil layer, which has also been previously suggested by other studies. The fact that fairy circles store a particularly large amount of water for a long time in lower soil layers of 70 cm to 100 cm depth is irrelevant for the rapidly dying seedlings in the upper 10 cm of soil, because it is mainly the highly competitive grasses at the edge of the circles that benefit from this deep water source. These arrange themselves in a round shape, because of all geometric shapes, a circle has the smallest circumference-to-area ratio. Thus, each individual plant on the fairy circle perimeter benefits maximally from the water source from greater depths.

Our in PPEES published data also show that the dying grasses had even longer roots inside the fairy circles than the vital grasses outside, because they invested resources into tapping soil water from deeper layers. Our many image comparisons of plant roots of dead and vital grasses also demonstrate that root herbivory by termites was not present because the wilting grasses inside the fairy circles were completely undamaged when they initially died. Hence, termite herbivory can neither explain the death of the grasses, nor could such biomass consumption explain why the dying grasses inside the circles had even significantly longer roots than the green and vital grasses outside in the surrounding matrix. Several independent fairy circle researchers stated in The New York Times that our new research “conclusively” showed that “contrary to popular belief, termite activity does not cause the fairy circles.”

The results were also summarized in “Solving the fairy circle mystery using scientific evidence” published by Conservation Namibia and the Namibian Chamber of Environment.

In times of climate change and prolonged droughts, researchers are increasingly interested in studying the ability of plants to self-organize and redistribute scarce resources, as media releases by CNN and The Washington Post have highlighted. In this endeavor, the fairy circles are a shining example and may inspire further research on this topic in the future.

Link to Press Release
Link to Additional Images
Link to YouTube-Video, Part 1
Link to YouTube-Video, Part 2

Publications [with PDF]
		Getzin, S., Yizhaq, H., Muñoz-Rojas, M. & Erickson, T.E. (submitted as Matters Arising) The link between termite linyji and ‘fairy circles’ does not explain the cause of this specific vegetation pattern in Australia. Nature Ecology & Evolution.
		Getzin, S., Löns, C., Yizhaq, H., Erickson, T. E., Muñoz-Rojas, M., Huth, A. & Wiegand, K. (2022) High-resolution images and drone-based LiDAR reveal striking patterns of vegetation gaps in a wooded spinifex grassland of Western Australia. Landscape Ecology, 37, 829-845. [PDF]
		Getzin, S., Yizhaq, H. & Tschinkel, W.R. (2021) Definition of “fairy circles” and how they differ from other common vegetation gaps and plant rings. Journal of Vegetation Science, 32:e13092. https://doi.org/10.1111/jvs.13092. [PDF]
		Getzin, S., Nambwandja, A., Holch, S. & Wiegand, K. (2021) Revisiting Theron’s hypothesis on the origin of fairy circles after four decades: Euphorbias are not the cause. BMC Ecology and Evolution, 21, 102. [PDF]
		Getzin, S., Erickson, T. E., Yizhaq, H., Muñoz-Rojas, M., Huth, A. & Wiegand, K. (2021) Bridging ecology and physics: Australian fairy circles regenerate following model assumptions on ecohydrological feedbacks. Journal of Ecology, 109, 399-416. [PDF]
		Getzin, S., Yizhaq, H., Cramer, M. D. & Tschinkel, W. R. (2019) Contrasting global patterns of spatially periodic fairy circles and regular insect nests in drylands. Journal of Geophysical Research: Biogeosciences, 124, 3327-3342. [PDF]
		Getzin, S., Yizhaq, H., Muñoz-Rojas, M., Wiegand, K. & Erickson, T. E. (2019) A multi-scale study of Australian fairy circles using soil excavations and drone-based image analysis. Ecosphere, 10(2), e02620. [PDF]
		Getzin, S. & Yizhaq, H. (2019) Unusual Namibian fairy circle patterns in heterogeneous and atypical environments. Journal of Arid Environments, 164, 85-89. [PDF]
		Chanthorn, W., Wiegand, T., Getzin, S., Brockelman, W.Y. & Nathalang, A. (2018) Spatial patterns of local species richness reveal importance of frugivores for tropical forest diversity. Journal of Ecology, 106, 925-935. [PDF]
		Getzin, S., Fischer, R., Knapp, N. & Huth, A. (2017) Using airborne LiDAR to assess spatial heterogeneity in forest structure on Mount Kilimanjaro. Landscape Ecology, 32, 1881-1894. [PDF]
		Velázquez, E., Martínez, I., Getzin, S., Moloney, K.A. & Wiegand, T. (2016) An evaluation of the state of spatial point pattern analysis in ecology. Ecography, 39, 1042-1055. [PDF]
		Getzin, S., Yizhaq, H., Bell, B., Erickson, T.E., Postle, A.C., Katra, I., Tzuk, O., Zelnik, Y.R., Wiegand, K., Wiegand, T. & Meron, E. (2016) REPLY TO WALSH ET AL.: Hexagonal patterns of Australian fairy circles develop without correlation to termitaria. PNAS, 113, E5368-E5369. [PDF]
		Getzin, S., Yizhaq, H., Bell, B., Erickson, T.E., Postle, A.C., Katra, I., Tzuk, O., Zelnik, Y.R., Wiegand, K., Wiegand, T. & Meron, E. (2016) Discovery of fairy circles in Australia supports self-organization theory. PNAS, 113, 3551-3556. [PDF]
		Getzin, S., Wiegand, K., Wiegand, T., Yizhaq, H., von Hardenberg, J. & Meron, E. (2015) Clarifying misunderstandings regarding vegetation self-organization and spatial patterns of fairy circles in Namibia: a response to recent termite hypotheses. Ecological Entomology, 40, 669-675. [PDF]
		Getzin, S., Wiegand, K., Wiegand, T., Yizhaq, H., von Hardenberg, J. & Meron, E. (2015) Adopting a spatially explicit perspective to study the mysterious fairy circles of Namibia. Ecography, 38, 1-11. [PDF]
		Punchi-Manage, R., Wiegand, T., Wiegand, K., Getzin, S., Huth, A., Gunatilleke, C.V.S. & Gunatilleke, I.A.U.N. (2015) Neighborhood diversity of large trees shows independent species patterns in a mixed dipterocarp forest in Sri Lanka. Ecology, 96, 1823-1834. [PDF]
		Getzin, S., Nuske, R.S. & Wiegand, K. (2014) Using unmanned aerial vehicles (UAV) to quantify spatial gap patterns in forests. Remote Sensing, 6, 6988-7004. [PDF]
		Getzin, S., Wiegand, T. & Hubbell, S.P. (2014) Stochastically driven adult-recruit associations of tree species on Barro Colorado Island. Proceedings of the Royal Society B, 281, 20140922. [PDF]
		Nguyen, H., Wiegand, K. & Getzin, S. (2014) Spatial patterns and demographics of Streblus macrophyllus trees in a tropical evergreen forest, Vietnam. Journal of Tropical Forest Science, 26, 309-319. [PDF]
		Nguyen, H., Wiegand, K. & Getzin, S. (2014) Spatial distributions of tropical tree species in northern Vietnam under environmentally variable site conditions. Journal of Forestry Research, 25, 257-268. [PDF]
		Punchi-Manage, R., Wiegand, T., Wiegand, K., Getzin, S., Gunatilleke, C.V.S. & Gunatilleke, I.A.U.N. (2014) Effect of spatial processes and topography on structuring species assemblages in a Sri Lankan dipterocarp forest. Ecology, 95, 376-386. [PDF]
		Zhu, Y., Getzin, S., Wiegand, T., Ren, H. & Ma, K. (2013) The relative importance of Janzen-Connell effects in influencing the spatial patterns at the Gutianshan subtropical forest. PLoS ONE, 8, e74560. [PDF]
		Gossner, M.M., Getzin, S., Lange, M., Pašalic, E., Türke, M., Wiegand, K. & Weisser, W.W. (2013) The importance of heterogeneity revisited from a multiscale and multitaxa approach. Biological Conservation, 166, 212-220. [PDF]
		Ward, D., Wiegand, K. & Getzin, S. (2013) Walter's two-layer hypothesis revisited: back to the roots! Oecologia, 172, 617-630. [PDF]
		Punchi-Manage, R., Getzin, S., Wiegand, T., Kanagaraj, R., Gunatilleke, C.V.S., Gunatilleke, I.A.U N., Wiegand, K. & Huth, A. (2013) Effects of topography on structuring local species assemblages in a Sri Lankan mixed dipterocarp forest. Journal of Ecology, 101, 149-160. [PDF]
		Wiegand, T., Huth, A., Getzin, S., Wang, X., Hao, Z., Gunatilleke, C.V.S. & Gunatilleke, I.A.U N. (2012) Testing the independent species' arrangement assertion made by theories of stochastic geometry of biodiversity. Proceedings of the Royal Society B, 279, 3312-3320. [PDF]
		Getzin, S., Wiegand, K. & Schoening, I. (2012) Assessing biodiversity in forests using very high-resolution images and unmanned aerial vehicles. Methods in Ecology and Evolution, 3, 397-404. [PDF]
		Lan, G., Getzin, S., Wiegand, T., Hu, Y., Xie, G., Zhu, H. & Cao, M. (2012) Spatial distribution and interspecific associations of tree species in a tropical seasonal rain forest of China. PLoS ONE, 7, e46074. [PDF]
		Getzin, S., Worbes, M., Wiegand, T. & Wiegand, K. (2011) Size dominance regulates tree spacing more than competition within height classes in tropical Cameroon. Journal of Tropical Ecology, 27, 93-102. [PDF]
		Getzin, S., Wiegand, T., Wiegand, K. & He, F. (2008) Heterogeneity influences spatial patterns and demographics in forest stands. Journal of Ecology, 96, 807-820. [PDF]
		Moustakas, A., Wiegand, K., Getzin, S., Ward, D., Meyer, K.M., Guenther, M. & Mueller, K.-H. (2008) Spacing patterns of an Acacia tree in the Kalahari over a 61-year period: how clumped becomes regular and vice versa. Acta Oecologica, 33, 355-364. [PDF]
		Getzin, S., Wiegand, K., Schumacher, J. & Gougeon, F.A. (2008) Scale-dependent competition at the stand level assessed from crown areas. Forest Ecology and Management, 255, 2478-2485. [PDF]
		Getzin, S. & Wiegand, K. (2007) Asymmetric tree growth at the stand level: Random crown patterns and the response to slope. Forest Ecology and Management, 242, 165-174. [PDF]
		Getzin, S. (2007) Structural Fire Effects in the World's Savannas. A Synthesis for Biodiversity and Land-Use Managers. VDM Verlag, Saarbruecken. Book-ISBN: 978-3-8364-3664-9
		Getzin, S., Dean, C., He, F., Trofymow, J.A., Wiegand, K. & Wiegand, T. (2006) Spatial patterns and competition of tree species in a Douglas-fir chronosequence on Vancouver Island. Ecography, 29, 671-682. [PDF]
		Getzin, S. (2005) The suitability of the degradation gradient method in arid Namibia. African Journal of Ecology, 43, 340-351. [PDF]
		Becker, T. & Getzin, S. (2000) The fairy circles of Kaokoland (North-West-Namibia) - origin, distribution, and characteristics. Basic and Applied Ecology, 1, 149-159. [PDF]