title: Spatial patterns of an endemic Mediterranean palm recolonizing old fields.
abstract: Throughout Europe, increased levels of land abandonment lead to (re)colonization of old lands by forests and shrublands. Very little is known about the spatial pattern of plants recolonizing such old fields. We mapped in two 21-22-ha plots, located in the Doñana National Park (Spain), all adult individuals of the endozoochorous dwarf palmChamaerops humilisL. and determined their sex and sizes. We used techniques of spatial point pattern analysis (SPPA) to precisely quantify the spatial structure of theseC. humilispopulations. The objective was to identify potential processes generating the patterns and their likely consequences on palm reproductive success. We used (1) Thomas point process models to describe the clustering of the populations, (2) random labeling to test the sexual spatial segregation, and (3) mark correlation functions to assess spatial structure in plant sizes. Plants in both plots showed two critical scales of clustering, with small clusters of a radius of 2.8-4 m nested within large clusters with 38-44 m radius. Additional to the clustered individuals, 11% and 27% of allC. humilisindividuals belonged to a random pattern that was independently superimposed to the clustered pattern. The complex spatial pattern ofC. humiliscould be explained by the effect of different seed-dispersers and predators' behavior and their relative abundances. Plant sexes had no spatial segregation. Plant sizes showed a spatial aggregation inside the clusters, with a decreasing correlation with distance. Clustering ofC. humilisis strongly reliant on its seed dispersers and stressful environmental conditions. However, it seems that the spatial patterns and dispersal strategies of the dwarf palm make it a successful plant for new habitat colonization. Our results provide new information on the colonization ability ofC. humilisand can help to develop management strategies to recover plant populations.
authors.affiliation: Department of Conservation Biology Estación Biológica de Doñana (EBD-CSIC) Seville Spain.
authors.forename: Miguel E
authors.initials: ME
authors.lastname: Jácome-Flores
authors.affiliation: Department of Conservation Biology Estación Biológica de Doñana (EBD-CSIC) Seville Spain.
authors.forename: Miguel
authors.initials: M
authors.lastname: Delibes
authors.affiliation: Department of Ecological Modelling Helmholtz Centre for Environmental Research GmbH - UFZ Leipzig Germany; German Centre for Integrative Biodiversity Research (iDiv) Halle-Jena-Leipzig Leipzig Germany.
authors.forename: Thorsten
authors.initials: T
authors.lastname: Wiegand
authors.affiliation: Department of Conservation Biology Estación Biológica de Doñana (EBD-CSIC) Seville Spain; Department of Ecological Modelling Helmholtz Centre for Environmental Research GmbH - UFZ Leipzig Germany; Technical University of Lisbon Institute of Agronomy Centre for Applied Ecology Lisboa Portugal.
authors.forename: José M
authors.initials: JM
authors.lastname: Fedriani
keywords: C. humilis; Mediterranean scrubland; Thomas point process models; colonization front; endozoochorous seed dispersal; plant size patterns; point pattern analysis