title: Emerged or imposed: a theory on the role of physical templates and self-organisation for vegetation patchiness.
abstract: In this article, we develop a unifying framework for the understanding of spatial vegetation patterns in heterogeneous landscapes. While much recent research has focused on self-organised vegetation the prevailing view is still that biological patchiness is mostly due to top-down control by the physical landscape template, disturbances or predators. We suggest that vegetation patchiness in real landscapes is controlled both by the physical template and by self-organisation simultaneously, and introduce a conceptual model for the relative roles of the two mechanisms. The model considers four factors that control whether vegetation patchiness is emerged or imposed: soil patch size, plant size, resource input and resource availability. The last three factors determine the plant-patch size, and the plant-to-soil patch size ratio determines the impact of self-organisation, which becomes important when this ratio is sufficiently small. A field study and numerical simulations of a mathematical model support the conceptual model and give further insight by providing examples of self-organised and template-controlled vegetation patterns co-occurring in the same landscape. We conclude that real landscapes are generally mixtures of template-induced and self-organised patchiness. Patchiness variability increases due to source-sink resource relations, and decreases for species of larger patch sizes.
authors.affiliation: Robert H. Smith Institute of Plant Sciences and Genetics in Agriculture, Faculty of Agricultural, Food and Environmental Quality Sciences, The Hebrew University of Jerusalem, P.O. Box 12, Rehovot, 76100, Israel. efrat.sheffer@mail.huji.ac.il
authors.forename: Efrat
authors.initials: E
authors.lastname: Sheffer
authors.forename: Jost
authors.initials: J
authors.lastname: von Hardenberg
authors.forename: Hezi
authors.initials: H
authors.lastname: Yizhaq
authors.forename: Moshe
authors.initials: M
authors.lastname: Shachak
authors.forename: Ehud
authors.initials: E
authors.lastname: Meron
mesh_terms: D017753:Ecosystem; D007091:Image Processing, Computer-Assisted; D007557:Israel; D008954:Models, Biological; D008962:Models, Theoretical; D010944:Plants; D031785:Poa / Q000502:physiology; D027824:Rosaceae / Q000502:physiology; D012987:Soil
chemical_list: D012987:Soil