Where do seeds go when they go far? Distance and directionality of avian seed dispersal in heterogeneous landscapes

Abstract

Abstract. Seed dispersal at large scales strongly influences plant population dynamics. Still, ecologists have rarely measured seed dispersal at relevant scales, and the role of habitat types in affecting seed dispersal at long distances remains unexplored. We studied seed dispersal of Ilex aquifolium and Crataegus monogyna in northern Spain, hypothesizing that seeds would be recovered at higher rates and at longer distances (LDD) at habitats with fleshyfruited trees, compared to habitats with other tree types or at open habitats. We tracked seeds in eight landscapes by enriching trees with 15 N isotopes at the center of landscapes, and then detected 15 N-marked seeds by sampling at distances of up to 700 m. We found that seeds arrive in greater densities and at longer distances in habitats with trees, particularly fleshyfruited types, producing different LDD probabilities for each habitat. Results also show a disproportional arrival of seeds in habitats similar to those of mother plants, which should affect seed establishment and the genetic diversity of plant neighborhoods. Findings reveal the strong dependence of seed dispersal on the existing templates that guide the movements of avian dispersers in heterogeneous landscapes and also suggest that LDD above tree lines and beyond hard habitat edges can be difficult.

Connecting Resource Tracking by Frugivores to Temporal Variation in Seed Dispersal Networks

“…Indeed, in a desert grassland and a temperate heterogeneous system seed deposition was higher under fruiting canopies Carlo and Tewksbury, 2014). Carlo et al (2013) found that long distance dispersal events (distances of 150-700 m) were much more likely to occur under fruiting canopies than non-fruiting. Long distance dispersal events are important for plant community stability by maintaining gene flow.…”

Geographic consistency in the seed dispersal patterns of Taxus baccata L. in the Iberian Peninsula

“…For the "rock" microhabitat, due to the difficulty to install seed traps and their conspicuousness to animals (including frugivores), we collected the seeds directly from open quadrats, permanently marked on the rock substrate, with the same surface than seed traps. Seed predation by rodents is usually low in open microhabitats and it mostly occurs in late winter (Hulme, 1997;García et al, 2005a), and thus seed losses due to predation were considered negligible (see García et al, 2011;Carlo et al, 2013;Lavabre et al, 2014, for validation of the methodology). In Peña Mayor and Escobarejos, we also sampled seed deposition in permanently labelled open quadrats of 0.5×0.5 m, as the presence of abundant free-ranging cattle and human activities in these two sites prevented the use of seed traps.…”

Hierarchical mechanisms of spatially contagious seed dispersal in complex seed‐disperser networks

“…Third, linking individual disperser species to the disseminated seeds is often technically difficult and thus the contribution of particular animal dispersers to the overall seed rain often remains unknown (Côrtes and Uriarte 2013). The alternative task of quantifying multispecies compound seed rains generated by several dispersers is rarely completed because it is logistically and analytically arduous (but see Carlo et al 2013). Finally, because seed distribution resulting from such plant-animal interactions is likely to be scale and context dependent (Kollmann 2000, Carlo and Morales 2008, Garcı´a et al 2011, finding general patterns often proves challenging (Agrawal et al 2007).…”