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 palm Chamaerops humilis L. and determined their sex and sizes. We used techniques of spatial point pattern analysis (SPPA) to precisely quantify the spatial structure of these C. humilis populations. 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 all C. humilis individuals belonged to a random pattern that was independently superimposed to the clustered pattern. The complex spatial pattern of C. humilis could 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 of C. humilis is 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 of C. humilis and can help to develop management strategies to recover plant populations.

Differential pollinator response underlies plant reproductive resilience after fires

“…Ants are erratic and infrequent visitors and also unlikely to pollinate this dioecious plant. There have been suggestions that wind could also play a role in pollination of C. humilis (Herrera, 1989;Jácome-Flores et al, 2016). Although most previous evidence does not support this possibility (Anstett, 1999;, we experimentally test it here (see Results).…”

Interaction motifs variability in a Mediterranean palm under environmental disturbances: the mutualism–antagonism continuum

“…Data are available from the Dryad Digital Repository: <http://dx.doi.org/10.5061/dryad.8w9ghx3h2> (Jácome‐Flores et al ).…”

“…To estimate the quality component (QLY, hereafter) we compiled available data from previous works on C. humilis seed dispersal in the Doñana National Park made in open areas in dehesa (Fedriani and Delibes 2011, Perea et al 2013, Suárez-Esteban et al 2013, Jácome-Flores et al 2016, Castañeda et al 2017) regarding: 1) fruit handling and fruit processing behaviour; 2) seed germination of handled and defecated/regurgitated seeds; and 3) probability of seedling survival. The cumulative probability is calculated from the product of the three probabilities: i.e.…”

Community‐wide seed dispersal distances peak at low levels of specialisation in size‐structured networks

“…Theoretical work has highlighted conspecific spatial clustering as a mechanism reducing competitive exclusion and promoting diversity (Hubbell and Foster 1986, Chave et al 2002). Empirical work has demonstrated that between‐species variability in seed dispersal distances leads to differences in spatial clustering of plants, such that species with shorter seed dispersal distances are more tightly clustered in space than species with longer seed dispersal distances (Seidler and Plotkin 2006, Jácome‐Flores et al 2016). In our simulations, we found no variability between seed dispersal distances across plant species under a scenario that lacked niche partitioning (Fig.…”