Wiegand, Kerstin

[["dc.bibliographiccitation.firstpage","399"],["dc.bibliographiccitation.journal","Journal of Ecology"],["dc.bibliographiccitation.lastpage","416"],["dc.bibliographiccitation.volume","109"],["dc.contributor.author","Getzin, Stephan"],["dc.contributor.author","Erickson, Todd E."],["dc.contributor.author","Yizhaq, Hezi"],["dc.contributor.author","Muñoz‐Rojas, Miriam"],["dc.contributor.author","Huth, Andreas"],["dc.contributor.author","Wiegand, Kerstin"],["dc.date.accessioned","2020-12-08T08:09:43Z"],["dc.date.available","2020-12-08T08:09:43Z"],["dc.date.issued","2021"],["dc.description.abstract","1. So‐called fairy circles (FCs) comprise a spatially periodic gap pattern in arid grasslands of Namibia and north‐west Western Australia. This pattern has been explained with scale‐dependent ecohydrological feedbacks and the reaction‐diffusion, or Turing mechanism, used in process‐based models that are rooted in physics and pattern‐formation theory. However, a detailed ecological test of the validity of the modelled processes is still lacking. 2. Here, we test in a spinifex‐grassland ecosystem of Western Australia the presence of spatial feedbacks at multiple scales. Drone‐based multispectral analysis and spatially explicit statistics were used to test if grass vitality within five 1‐ha plots depends on the pattern of FCs that are thought to be a critical extra source of water for the surrounding matrix vegetation. We then examined if high‐ and low‐vitality grasses show scale‐dependent feedbacks being indicative of facilitation or competition. Additionally, we assessed facilitation of grass plants for different successional stages after fire at fine scales in 1‐m2 quadrats. Finally, we placed soil moisture sensors under bare soil inside the FC gap and under plants at increasing distances from the FC to test if there is evidence for the ‘infiltration feedback’ as used in theoretical modelling. 3. We found that high‐vitality grasses were systematically more strongly associated with FCs than low‐vitality grasses. High‐vitality grasses also had highly aggregated patterns at short scales being evidence of positive feedbacks while negative feedbacks occurred at larger scales. Within 1‐m2 quadrats, grass cover and mutual facilitation of plants was greater near the FC edge than further away in the matrix. Soil moisture after rainfall was lowest inside the FC with its weathered surface crust but highest under grass at the gap edge, and then declined towards the matrix, which confirms the infiltration feedback. 4. Synthesis. The study shows that FCs are a critical extra source of water for the dryland vegetation, as predicted by theoretical modelling. The grasses act as ‘ecosystem engineers’ that modify their hostile, abiotic environment, leading to vegetation self‐organization. Overall, our ecological findings highlight the validity of the scale‐dependent feedbacks that are central to explain this emergent grassland pattern via the reaction‐diffusion or Turing‐instability mechanism."],["dc.description.sponsorship","German Research Foundation ‐ DFG"],["dc.identifier.doi","10.1111/1365-2745.13493"],["dc.identifier.uri","https://resolver.sub.uni-goettingen.de/purl?gro-2/69461"],["dc.language.iso","en"],["dc.notes.intern","DeepGreen Import"],["dc.relation.issn","0022-0477"],["dc.relation.issn","1365-2745"],["dc.relation.orgunit","Abteilung Ökosystemmodellierung"],["dc.rights","CC BY 4.0"],["dc.subject.gro","ecosystem engineer"],["dc.subject.gro","Normalized Difference Vegetation Index"],["dc.subject.gro","reaction-diffusion mechanism"],["dc.subject.gro","scale-dependent feedback"],["dc.subject.gro","spatial periodicity"],["dc.subject.gro","Turing dynamics"],["dc.subject.gro","unmanned aerial vehicle"],["dc.subject.gro","vegetation self-organization"],["dc.title","Bridging ecology and physics: Australian fairy circles regenerate following model assumptions on ecohydrological feedbacks"],["dc.type","journal_article"],["dc.type.internalPublication","yes"],["dc.type.subtype","original_ja"],["dspace.entity.type","Publication"]]

[["dc.bibliographiccitation.artnumber","e02620"],["dc.bibliographiccitation.issue","2"],["dc.bibliographiccitation.journal","Ecosphere"],["dc.bibliographiccitation.volume","10"],["dc.contributor.author","Getzin, Stephan"],["dc.contributor.author","Yizhaq, Hezi"],["dc.contributor.author","Muñoz-Rojas, Miriam"],["dc.contributor.author","Wiegand, Kerstin"],["dc.contributor.author","Erickson, Todd E."],["dc.date.accessioned","2019-07-09T11:50:12Z"],["dc.date.available","2019-07-09T11:50:12Z"],["dc.date.issued","2019"],["dc.description.abstract","Fairy circles (FCs) are extremely ordered round patches of bare soil within arid grasslands of southwestern Africa and northwestern Australia. Their origin is disputed because biotic factors such as insects or abiotic factors such as edaphic and eco-hydrological feedback mechanisms have been suggested to be causal. In this research, we used a multi-scale approach to shed light on the origin of Australian FCs. At a local scale, we investigated the potential cause of FCs using analyses of soil compaction and texture within FCs, the surrounding matrix vegetation, and in nearby large bare-soil areas. We found that soil hardness and clay content were similarly higher inside the FCs and in the large bare-soil areas. When compared to the matrix soils with protective grass cover, the 2.6–2.8 times higher clay content in FCs and large bare-soil areas is likely sourced via multiple abiotic weathering processes. Intense rainfall events, particle dispersion, surface heat, evaporation, and mechanical crust building inhibit plant growth in both areas. At the landscape scale, a systematic survey of 154 soil excavations within FCs was undertaken to evaluate the presence of pavement termitaria that could inhibit plant growth. We show that in up to 100% and most of the excavations per plot, no hard pavement termitaria were present in the FCs. This fact is substantiated by the observation that small, newly forming FCs are initiated on soft sand without evidence of termite activity. At the regional scale, we investigated the spatial properties of FCs and common termite-created gaps in Western Australia, using spatially explicit statistics. We mapped three 25-ha FC plots with a drone and compared them with three aerial images of typical vegetation gaps created by harvester and spinifex termites. We demonstrate that the small diameters, the lower ordering, and the heterogeneous patterns of these common termite gaps strongly differ from the unique spatial signature of FCs. Our multi-scale approach emphasizes that FCs are not trivial termite gaps and that partial correlation with termites at some sites does not imply causation. Instead, we highlight the need to study the edaphic and ecohydrological drivers of vegetation-pattern formation in water-limited environments."],["dc.identifier.doi","10.1002/ecs2.2620"],["dc.identifier.purl","https://resolver.sub.uni-goettingen.de/purl?gs-1/15879"],["dc.identifier.uri","https://resolver.sub.uni-goettingen.de/purl?gro-2/59720"],["dc.language.iso","en"],["dc.notes.intern","Merged from goescholar"],["dc.relation.issn","2150-8925"],["dc.relation.orgunit","Abteilung Ökosystemmodellierung"],["dc.rights","CC BY 3.0"],["dc.rights.uri","https://creativecommons.org/licenses/by/3.0"],["dc.subject.ddc","570"],["dc.subject.gro","clay crust"],["dc.subject.gro","cyclone"],["dc.subject.gro","emergent vegetation patterns"],["dc.subject.gro","heterogeneity"],["dc.subject.gro","hydrology"],["dc.subject.gro","nearest-neighbor distance"],["dc.subject.gro","pair-correlation function"],["dc.subject.gro","spatial periodicity"],["dc.subject.gro","Triodia basedowii"],["dc.subject.gro","vegetation self-organization"],["dc.subject.gro","wavelength"],["dc.subject.gro","weathering"],["dc.title","A multi-scale study of Australian fairy circles using soil excavations and drone-based image analysis"],["dc.type","journal_article"],["dc.type.internalPublication","yes"],["dc.type.subtype","original_ja"],["dc.type.version","published_version"],["dspace.entity.type","Publication"]]