Does spatial heterogeneity blur the signature of dispersal syndromes on spatial patterns of woody species? A test in a tropical dry forest

Abstract

Spatial patterns of adult plants are a consequence of several ecological processes related to seed dispersal and recruitment. Dispersal limitation, mediated by dispersal syndrome, is considered a key factor in the formation of adult plant spatial patterns. Although this initial pattern determined by dispersal has been thoroughly studied, the subsequently modification by the effect of additional ecological factors, such as habitat heterogeneity is less understood. We explored the relative importance of dispersal syndrome and spatial heterogeneity on the realization of spatial patterns of adult trees in an Ecuadorian tropical dry forest. The spatial distribution of 28 species was modeled with four different spatial point processes each: homogeneous Poisson (HPP), inhomogeneous Poisson (IPP), homogeneous Poisson cluster (HPCP), and inhomogeneous Poisson cluster process (IPCP). These models allowed us to discern between effects of random processes, habitat heterogeneity, limited dispersal, and joint effects of habitat heterogeneity and limited dispersal. We employed Akaike's information criterion (AIC) to select the model which best fit the spatial pattern of each species. The best model of each species was used to analyze differences in cluster size and degree of aggregation, between dispersal syndromes. Seventy-five percent of the species showed inhomogeneous patterns. IPCP yielded the best fit for the spatial distribution of 50% of species in the studied forest and was the prevalent model for the three dispersal syndromes. Thus, the effect of spatial heterogeneity was prevalent in the distribution of most species in this dry tropical forest. Only 21% of species had spatial patterns compatible with random mechanisms associated to limited dispersal around parent sources. Clearly, ignoring habitat heterogeneity could bias the analysis of relationships between dispersal syndrome and species patterns.

Spatial distribution and interspecific associations in a deciduous broad‐leaved forest in north‐central China

“…The resulting variations of conspecific aggregation might be caused by habitat association and dispersal limitation. Moreover, the limitated dispersal can be mediated by the dispersal syndrome (Jara‐Guerrero et al., ). It has been confirmed that the distribution of wind‐dispersed species is dispersed less than that of animals, and tends to generate a pattern of aggregation (Condit et al., ; Seidler & Plotkin, ).…”

“…It has been confirmed that dispersal limitation is the key factor affecting the degree of stump clumping, regardless of habitat heterogeneity in a tropical forest (Hardy & Sonké, ; Seidler & Plotkin, ). In addition, differences in seed dispersal syndrome, which are related to morphological attributes, may contribute to structuring and maintaining the assemblage of species in the forest community (Hubbell, ; Jara‐Guerrero, De la Cruz, Espinosa, Méndez, & Escudero, ; Seidler & Plotkin, ; Song et al., ). However, dispersion limitation is often discussed with other niche‐based processes such as habitat filtering and species interaction since it cannot explain the distribution of species by itself.…”

The effects of individual tree species on species diversity in a tropical dry forest change throughout ontogeny

“…The predominance of neutral species in the ISAR analyses, where the null models explicitly accounted for spatial heterogeneity, and the absence of a clear relationship between dispersal limitation and ISAR behavior (Supplementary material Appendix 2, Table A2), discards the prevalence of key species and instead points to the existence of environmental filters. In fact, Jara‐Guerrero et al () have documented that the spatial distribution of 75% of REMA species respond to some kind of environmental heterogeneity.…”

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., ).…”