Maintaining distances with the engineer: patterns of coexistence in plant communities beyond the patch‐bare dichotomy

Abstract

SummaryTwo-phase plant communities with an engineer conforming conspicuous patches and affecting the performance and patterns of coexisting species are the norm under stressful conditions.To unveil the mechanisms governing coexistence in these communities at multiple spatial scales, we have developed a new point-raster approach of spatial pattern analysis, which was applied to a Mediterranean high mountain grassland to show how Festuca curvifolia patches affect the local distribution of coexisting species.We recorded 22 111 individuals of 17 plant perennial species. Most coexisting species were negatively associated with F. curvifolia clumps. Nevertheless, bivariate nearest-neighbor analyses revealed that the majority of coexisting species were confined at relatively short distances from F. curvifolia borders (between 0-2 cm and up to 8 cm in some cases).Our study suggests the existence of a fine-scale effect of F. curvifolia for most species promoting coexistence through a mechanism we call 'facilitation in the halo'. Most coexisting species are displaced to an interphase area between patches, where two opposite forces reach equilibrium: attenuated severe conditions by proximity to the F. curvifolia canopy (nutrientrich islands) and competitive exclusion mitigated by avoiding direct contact with F. curvifolia.

What causes conspecific plant aggregation? Disentangling the role of dispersal, habitat heterogeneity and plant–plant interactions

“…alpina appear interspersed within the community. Previous studies in this community found that neither the dominant F. curvifolia nor the shrub species affect the spatial distribution of S. ciliata (Pescador et al ).…”

“…50 cm: Lara‐Romero et al ). Pescador et al () observed that habitat heterogeneity in the psychroxerophyllous pastures where this species lives affects its spatial pattern, as some areas had more favourable abiotic conditions for the species’ occurrence. Furthermore, previous studies suggest that adults have a facilitative effect on recruits by providing shade and better soil conditions including the amelioration of water availability (Lara‐Romero et al ).…”

The assembly of a plant network in alpine vegetation

“…First, for each species’ spatial pattern, we fitted models of fine‐scale spatial distribution that accounted for the effects of environmental heterogeneity and limited dispersal (Pescador et al., ; Jara‐Guerrero et al., ; Chacon‐Labella et al., ; see Supporting information for details). Then, we assessed interspecific spatial associations using bivariate point‐pattern analysis (Baddeley et al., ).…”

“…Environmental heterogeneity, dispersal and biotic interactions shape the fine‐scale distribution of organisms and affect the spatial structure of populations, communities and ecosystems (Kefi, Rietkerk, van Baalen, & Loreau, ; Meron, ; Rietkerk, Dekker, de Ruiter, & van de Koppel, ). For instance, facilitation can induce fine‐scale associations (Bruno, Stachowicz, & Bertness, ; Chacon‐Labella, de la Cruz, & Escudero, ; Schöb, Kammer, Kikvidze, Choler, & Veit, ) while competition can reduce them (Durrett & Levin, ; MacArthur & Levins, ; Pescador, Chacon‐Labella, de la Cruz, & Escudero, ; Tilman, ). The structure of plant communities can therefore be seen as a complex network of positive and negative interactions among species (Levine, Bascompte, Adler, & Allesina, ; Losapio, Pugnaire, O'Brien, & Schöb, ; Saiz, Gomez‐Gardeñes, Borda, & Maestre, ; Verdù & Valiente‐Banuet, ).…”

Colonization in Mediterranean old‐fields: the role of dispersal and plant–plant interactions

“…Although χ 2 tests ignore the question of scale, they allow evaluating if P. sylvestris and J. communis individuals grow exactly under J. sabina canopies, an issue that spatial point‐pattern analyses do not fully cover (but see Pescador et al. ).…”