Plant clonal morphologies and spatial patterns as self-organized responses to resource-limited environments

Abstract

We propose here to interpret and model peculiar plant morphologies (cushions and tussocks) observed in the Andean Altiplano as localized structures. Such structures resulting in a patchy, aperiodic aspect of the vegetation cover are hypothesized to self-organize thanks to the interplay between facilitation and competition processes occurring at the scale of basic plant components biologically referred to as ‘ramets’. (Ramets are often of clonal origin.) To verify this interpretation, we applied a simple, fairly generic model (one integro-differential equation) emphasizing via Gaussian kernels non-local facilitative and competitive feedbacks of the vegetation biomass density on its own dynamics. We show that under realistic assumptions and parameter values relating to ramet scale, the model can reproduce some macroscopic features of the observed systems of patches and predict values for the inter-patch distance that match the distances encountered in the reference area (Sajama National Park in Bolivia). Prediction of the model can be confronted in the future with data on vegetation patterns along environmental gradients so as to anticipate the possible effect of global change on those vegetation systems experiencing constraining environmental conditions.

Light-mediated self-organization of sunflower stands increases oil yield in the field

“…This process results in the alternate orientation of plant shoots that improves oil yield per unit area. This finding is completely different from other plant selforganized population structures (21)(22)(23)(24)(25), where the occurrence of changes in demography is a stringent condition for emergence of self-organized patterns (26). The propagation of a sensory signal among plants is central to the system presented here, which therefore compares better to the communication networks leading to self-organized structures in social insects (27) than to previously described self-organized plant population structures.…”

“…At the organ level in plants, for example, the frequency distribution of seeds per fruit can be explained by simple rules of resource flow into ovules, random processes, and hormonemediated positive feedback (21). At the population and community level, self-organization can lead to plant arrangements in rings, lines, labyrinths, or bands (23)(24)(25). This self-organization process results from the balance between facilitation and competition that alters resource availability, plant survival, and demography (26).…”

Fine nurse variations explain discrepancies in the stress‐interaction relationship in alpine regions

“…Interaction involving tussock grasses in tropical alpine systems suggested that the periphery of tussocks were less subject to root and aerial competition for resources (Couteron et al ). Although aerial competition may not shift between the periphery and the centre of cushions, the vicinity of bare soil and the probable reduction of root density in the periphery are expected to reduce competition, thus promoting net facilitative interactions.…”

Vegetation ring formation by water overland flow in water‐limited environments: Field measurements and mathematical modelling

“…Much effort has been devoted to modelling water‐limited landscapes and understanding self‐organized patchiness (Borgogno, D'Odorico, Laio, & Ridolfi, ; Deblauwe, Barbier, Couteron, Lejeune, & Bogaert, ; Getzin et al, ; Gilad, von Hardenberg, Provenzale, Shachak, & Meron, , ; Rietkerk, Dekker, De Ruiter, & Van de Koppel, ; Rietkerk & Van de Koppel, ; Yizhaq, Stavi, Shachak, & Bel, ; Zelnik, Meron, & Bel, ). Very few model studies, however, have been devoted to patterns that emerge at the single‐patch scale, such as spots, rings, crescent‐like shapes, and spirals, and to the biomass–water relationships associated with them (Couteron et al, ; Fernandez‐Oto, Escaff, & Cisternas, ; Meron, Yizhaq, & Gilad, ; Sheffer et al, ; Sheffer, Yizhaq, Gilad, Shachak, & Meron, ; Tlidi et al, ; Tlidi, Lefever, & Vladimirov, ). Model studies of self‐organized patchiness, at both the patch and landscape scales, are important for understanding the relationships among spatial heterogeneity, community structure, and ecosystem functioning (Nathan, Osem, Shachak, & Meron, ).…”