Dr. Stephan Getzin

Contact

Helmholtz Centre for Environmental Research - UFZ

Department of Ecological Modelling

Permoserstr. 15
04318 Leipzig
Germany

Tel.: +49 341 235-1716
Fax: +49 341 235-3500
stephan.getzin@ufz.de    

Stephan Getzin

Research Interests

  • Remotely Sensed Pattern Analysis
  • Spatial Statistics
  • Application of Unmanned Aerial Vehicles (UAV)
  • Tropical Forest Ecology
  • Biodiversity Experiments
  • Dryland Research
  • Self-Organization of Vegetation


16 Years of Fairy Circle Research and a Discovery

FCs

Since the year 2000, when we published the first ISI-listed article on fairy circles in the Web of Science (Becker & Getzin 2000), I am closely following the developments of fairy circle research. Many hypotheses on the origin of fairy circles have been proposed during the last 16 years and publication numbers are exponentially growing since two years. More recently, the vegetation self-organization hypothesis has become increasingly attractive to scientists. This hypothesis is mainly rooted in pattern formation theory and thus has been primarily published in mathematical and physical journals. Usually, such highly theoretical journals are not accessed by ecologists, however, also ecologists are nowadays more and more working on searching for field evidence in support of the vegetation self-organization theory.

In 2014, we have made an intriguing discovery on a novel fairy circle pattern in remote Australia. This is a true discovery because the very rare small-scale hexagonal and large-scale homogeneous pattern of the vegetation gaps has an identical spatial structure as the Namibian counterparts 10,000 km away. As we elaborated in our PNAS article, this observation is in line with a universality principle of pattern formation theory because symmetry breaking instabilities lead to universal patterns. The unique value of this new fairy circle pattern lies in the fact that these bare-soil gaps evolve even without correlation to termitaria or pavements. We dug out actively forming, large fairy circles (5-6 m in diameter) on deep sand which have only a thin mechanical crust layer yet, but no past or present termite activity was found at depths up to 30 cm (A-C). In these relatively young successional areas after past fire, some individual plants can still survive on sand inside the forming gaps. Such plant survival inside the gaps is only possible because extremely hard termite pavements are absent and the physical crusts on the surface of the sand have not yet undergone long enough mechanical weathering to fully prevent plant growth. Stronger plant inhibition will only happen with ongoing time and crust building when the gaps are becoming progressively circular and get a closed periphery due to overall growing plant cover in the surrounding matrix vegetation (D-F). The left images illustrate the formation of round gaps and different degrees of initial, still irregular gap shapes (J-E). Only plant self-organization is known to form such very large round gaps in the complete absence of termitaria because the plants likely form a circle to optimize their per-capita access to the run-off water provided by the gap centers. Consequently, these fairy circles are a “jewel” for the self-organization hypothesis because termites as a confounding agent can be excluded in such gaps. Unfortunately, fairy circles are often confused with well-known insect-created gaps in grasslands such as those caused by the North American harvester ants, fungus-growing termites in East Africa or Drepanotermes harvester termites in Australia. Though these small gaps are also round, their spatial patterns are much less ordered at small scales and they are heterogeneously distributed at the landscape scale. In our recent Reply to Walsh et al. we clarify that the well-known termite-created gaps or "desert circles" they address are different from the fairy circles that we excavated and that develop without any termite pavements.

The Australian outback becomes very hot with soil surface temperatures in gap centers reaching 75°C at noon. Depending on the degree of mechanical weathering and of runoff-erosion, the hardened soil crusts induce an increasingly strong infiltration contrast between individual grass plants and neighboring bare soil. Such infiltration contrasts also cause the large bare-soil areas with identical physical surface crusts being dozens or hundreds of meters in extent and that inhibit plant growth as in the fairy circles right next to these areas (K-M). The extreme heat and evaporation at the soil surface, the impact from rain droplets after heavy rainfall events, and the intense runoff-erosion processes in this harsh environment also cause the dominating Triodia grass to form circular gaps and striped or labyrinthine vegetation patterns in one and the same area (N,O). These transitions of labyrinthine to gapped patterns as a result of strong interaction between vegetation and runoff-erosion processes are also known from other arid landscapes across the globe and can be found in countries such as Sudan (P).



Research in the Media

CNN Headline Fairy Circles

The fairy circles of Namibia form a spectacular pattern in the arid grasslands along the Namib Desert. Our study published as “Editor’s choice” in Ecography appeared in several media such as CNN or BBC and the new PNAS paper on Australian fairy circles appeared in many more media (Altmetric Score). The actual scientific task lies in decoding “mysterious” self-organized systems by means of sophisticated pattern- and process-based analysis. From a scientific perspective, the fairy circles are a model system whose underlying mechanisms and processes are not easy to detect but whose mystery can be solved with a modern toolbox of analytical techniques.



DRONES Unmanned Aerial Vehicles (UAV)

Unmanned aerial vehicles (UAV) or drones are increasingly used for mapping natural habitats. We have started working with drones in 2008, at a time when the technology was not yet fully reliable. The project was covered in several media such as NATIONAL GEOGRAPHIC and had a press release at the University of Göttingen.

Since 2014 we have a new high-tech drone with several sensors such as a LiDAR for 3D-mapping, a multi-spectral camera, a thermal and a photo camera (left image). The central animated image shows a tree plantation of a biodiversity experiment. The 3D-LiDAR images represent different echos of the laser pulse. The lower image shows temperature isotherms of an open habitat with water ponds and bushes. This drone was recently introduced in an online article in SPEKTRUM. Also a media production made for a new ARTE documentary ("Die Neuvermessung der Welt") filmed the flight mission of our drone during mappings of forest and open habitat.



Publications

L2_gap1_klein 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.
Howe_small 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.
Spatial_Review 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.
FC_single_klein 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.
Fairy Circles 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.
Sri_Lanka3_klein 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.
Drohne 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.
BCI 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.
Vietnam2_klein Nguyen, H., Wiegand, K. & Getzin, S. (2014b) Spatial patterns and demographics of Streblus macrophyllus trees in a tropical evergreen forest, Vietnam. Journal of Tropical Forest Science, 26, 309–319.
Vietnam Nguyen, H., Wiegand, K. & Getzin, S. (2014a) Spatial distributions of tropical tree species in northern Vietnam under environmentally variable site conditions. Journal of Forestry Research, 25, 257-268.
Sinharaja 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.
Gutianshan 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.
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.
Walter Ward, D., Wiegand, K., Getzin, S. (2013) Walter's two-layer hypothesis revisited: back to the roots! Oecologia, 172, 617-630.

Sinharaja 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.

ProceedingsB 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.

cover_meeGetzin, 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.

Lan_et_al 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.



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.

Heterogeneity_OeM_GS1Getzin, S. , Wiegand, T., Wiegand, K. & He, F. (2008) Heterogeneity influences spatial patterns and demographics in forest stands. Journal of Ecology, 96, 807-820.

Dronfield_Ranch_RS_OeM_GS6Moustakas, 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.

Crown_Areas_OeM_GS4Getzin, 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.

Asymmetric_growth_OeM_GS2Getzin, 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.

Fire_OeM_GS8Getzin, 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

Chronopattern_OeM_GS3Getzin, 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.

Dis_Crowns_OeM_GS5Getzin, S. (2006) Analysis of hierarchical structures in forest stands using detailed spatial statistics. Ph.D. thesis

Waterhole_OeM_GS9Getzin, S. (2005) The suitability of the degradation gradient method in arid Namibia. African Journal of Ecology, 43, 340-351.

Fairy1_OeM_GS7 Becker, T. & Getzin, S. (2000) The fairy circles of Kaokoland (North-West-Namibia) - origin, distribution, and characteristics. Basic and Applied Ecology, 1, 149-159.