Guerrilla clonal growth strategy leads to amorphous pattern formation in a drylands vegetation model

Ecological Modelling, vol. 515, pp. 111510

Abstract

Resource concentration in the vicinity of plants is observed in drylands as a result of various mechanisms, developed to cope with water scarcity. This often leads to self-organized spatial patterns that enhance drylands’ ecosystem resilience to environmental changes. Numerous vegetation dynamics models have been developed over the past few decades to study this pattern formation. Generally, they represent plant spatial spread as a diffusive process, which captures well species that reproduce via seed dispersal or through clonal growth following the “phalanx” strategy, characterized by slow, compact expansion. However, many dryland species exhibit “guerrilla” clonal growth, characterized by rapid, directional exploration of favourable areas, which is poorly captured by diffusion. To address this limitation, we introduce a novel term for lateral biomass expansion into a classical dryland model. We found conditions suitable for periodic patterns to emerge with a Turing analysis, aiming to test the stability of a uniform solution against uniform and periodic perturbations. However, numerically, these patterns could not be observed by perturbing the homogeneous equilibria with small perturbations, possibly because of the non-linearity of the guerrilla expansion term. Instead, remarkably, the model produced amorphous, far-from-equilibrium patterns when integrated along a rainfall precipitation gradient. These findings highlight the need to represent the diversity of clonal plant strategies in dryland ecosystem models, as they play an important role in pattern formation and, thus, may influence ecosystem resilience and responses to global environmental change. Furthermore, our results highlight the need to move beyond linear analyses when studying systems with nonlinear dispersal dynamics. • Clonal growth is common among plants in dryland ecosystems • We introduce a novel model representing the main clonal growth types in drylands • Vegetation dominated by guerrilla clonal growth forms amorphous patterns • Nonlinear dispersal may require methods beyond classical linear stability analysis.

Authors 8

1. Andrea Davin corresponding

   University of Milano-Bicocca

   Affiliation as printed

   Department of Earth and Environmental Sciences, University of Milan-Bicocca, Milan, Italy

2. Jost v. Hardenberg

   Politecnico di Torino

   Affiliation as printed

   Department of Environment, Land and Infrastructure Engineering, Politecnico di Torino, Turin, Italy

3. Paul M. J. Berghuis

   Utrecht University · Royal Netherlands Institute for Sea Research

   Affiliation as printed

   Copernicus Institute of Sustainable Development, Environmental Sciences, Utrecht University, Utrecht, The Netherlands

   Department of Coastal Systems, Royal Netherlands Institute for Sea Research, Den Burg, The Netherlands

4. Ángeles G. Mayor

   University of Alicante

   Affiliation as printed

   Department of Ecology, University of Alicante, Alicante, Spain

5. Enrico Magazzino

   University of Padua

   Affiliation as printed

   Department of Land, Environment, Agriculture and Forestry (TESAF), University of Padova, Legnaro, Italy

   Interdepartmental Research Center of Geomatics (CIRGEO), University of Padova, Legnaro, Italy

6. Max Rietkerk

   Utrecht University

   Affiliation as printed

   Copernicus Institute of Sustainable Development, Environmental Sciences, Utrecht University, Utrecht, The Netherlands

7. Frits Veerman Aachen Mathematical Institute

   Leiden University

   Affiliation as printed

   Mathematical Institute, University of Leiden, Leiden, The Netherlands

8. Mara Baudena

   National Research Council · University of Palermo

   Affiliation as printed

   Institute for Atmospheric Sciences and Climate (ISAC), National Research Council (CNR), Turin, Italy

   National Biodiversity Future Center (NBFC), Palermo, Italy