Investigating the spatial mechanisms of self-organized vegetation gaps in arid Australia
Final Report Abstract
With this DFG-project on “Investigating the spatial mechanisms of self-organized vegetation gaps in arid Australia” we were able to shed light on the mysterious fairy circles and on basic principles of vegetation-pattern formation in water-limited environments. We have followed a holistic approach to investigating these highly ordered, spatially periodic vegetation gaps by employing comprehensive spatial analyses of remote-sensing data, quadrat-based sampling, soil excavations and soil texture analysis, as well as installing permanently recording soil-moisture sensors. Our analyses not only account for eco-hydrological feedbacks at different spatial scales but we also address temporal aspects of post-fire recovery of vegetation. In summary, all our empirical findings strongly support assumptions from modeling that are rooted in physics and mathematics, where Turing-like instabilities and resulting plant selforganization are thought to cause these periodic vegetation gaps. As we have concluded in Getzin et al. (2019): “By forming symmetric patterns, the vegetation benefits from the additional water resource provided by the FCs and thereby keeps the arid ecosystem functional at lower precipitation values compared with uniform vegetation. We consider FCs to be a striking example of the concept of emergence, where new patterns, processes, or structures appear at higher levels of organization that are not present at lower levels of organization.” The results of this DFG project can be seen as a bridge between empirical ecology and theoretical physics because so far only few studies have directly linked field-work observations with the theoretical modeling of vegetation self-organization. This DFG project was a productive cooperation with colleagues from Israel (Hezi Yizhaq) and Australia (Todd Erickson, Miriam Munoz-Rojas) who supported me in the field. Especially, Dr. Erickson from Kings Park/Perth, a seed expert being involved in mine-site rehabilitation, supported my field work logistically and in person whenever possible. Australian employers of Dr. Erickson (BHP mining, Kings Park Botanic Garden) also showed interest in this basic research because the Australian FCs occur in the very arid interior of Western Australia, where rehab experts of iron-ore mines have difficulties to restore local plants in disturbed areas. One potential, more applied aspect of this project can be to utilize detailed statistical knowledge on the self-organized plant patterns for rehabilitation purposes, i.e. seeds and young plants could be spatially arranged in a way that closely resembles their growth patterns in nature. Such innovations are still new but have been already suggested for rehabilitation purposes by, for example, Israelian physicists. Additionally, local Australians like mine-site related ecologists have also shown interest in the general techniques of drone-mapping, as applied during this project in 2017. Future will show in how far the basic research of this project will eventually be utilized in concrete applications. Irrespective of these uncertainties whether the knowledge gained during this research will affect industrial applications or not, the results of this project will have implications for other “mysterious” vegetation patterns around the globe, such as also the fairy circles of Namibia. This is because our research here has demonstrated that spatially periodic fairy circles can principally emerge “on their own” without being caused by external drivers such as termites or other causal agents. These specific insights will go into my current DFG project (Origin and dynamics of Namibian fairy circles assessed in-situ and by high-resolution spatio-temporal analysis) and will help to evaluate the drivers and spatial emergence of the Namibian fairy circles as objective as possible.
Publications
- (2017) Self-organized fairy circles versus common termite circles: the differences in spatial patterns matter! 6th International Conference on Drylands, Deserts & Desertification, Sede Boqer Campus, Israel, 07.11.2017
Getzin, S., Yizhaq, H., & Erickson, T. E.
- (2018) Fairy circles may form without termites: Australian evidence from drone-based image analysis and soil excavations, 48th Annual Meeting of the Ecological Society of Germany, Austria and Switzerland, Vienna, Austria, 12.09.2018
Getzin, S., Yizhaq, H., Munoz-Rojas, M., Wiegand, K. & Erickson, T. E.
- (2018) Pattern formation of fairy circles without termite correlation: insights from Australia and Namibia, 3rd Symposium of the A.F.W. Schimper-Foundation, Illmitz am Neusiedler See, Austria, 18.09.2018
Getzin, S., Yizhaq, H., 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
Getzin, S., Yizhaq, H., Munoz-Rojas, M., Wiegand, K. & Erickson, T. E.
(See online at https://doi.org/10.1002/ecs2.2620) - (2019) Contrasting global patterns of spatially periodic fairy circles and regular insect nests in drylands. Journal of Geophysical Research: Biogeosciences, 124, 3327–3342
Getzin, S., Yizhaq, H., Cramer, M. D. & Tschinkel, W. R.
(See online at https://doi.org/10.1029/2019JG005393) - (2019) Drone-based assessment of grass vitality in the Australian outback reveals emergent pattern formation of fairy circles, AGU (American Geophysical Union) Fall Meeting, San Francisco, USA, 12.12.2019
Getzin, S., Erickson, T. E., Yizhaq, H., Munoz-Rojas, M., Huth, A. & Wiegand, K.
- (2019) Drone-based assessment of grass vitality reveals emergent pattern formation of Australian fairy circles, 49th Annual Meeting of the Ecological Society of Germany, Austria and Switzerland, Münster, Germany, 11.09.2019
Getzin, S., Erickson, T. E., Yizhaq, H., Munoz-Rojas, M., Huth, A. & Wiegand, K.
