Can plant traits predict seed dispersal probability via red deer guts, fur, and hooves?

Tanja K Petersen,Hans Henrik Bruun

doi:10.1002/ece3.5512

Abstract

Seed dispersal by mammals provides functional connectivity between isolated plant habitat patches. Across much of Europe, red deer (Cervus elaphus) populations are growing steadily, potentially leading to increasing importance of this large mammal species to plant dispersal. While deer endozoochory is relatively well studied, epizoochory via fur and hoof attachment is much less understood. Seed dispersal internally and externally on 57 red deer individuals was investigated by sampling the seed content of intestinal tracts, fur, and hooves of animals shot during annual hunts in four contrasted landscapes in Denmark. We assessed compositional differences between dispersal modes whether plant species' association to a dispersal mode could be predicted by seed traits, whole‐plant traits, and species' local abundance. We found the largest difference in seed species composition to be between epizoochory (fur and hooves) and endozoochory (gut contents). Probability of plant dispersal through guts and fur was correctly predicted from traits more often than not. Hoof‐epizoochory, however, could not be correctly predicted from plant traits. Most plant species encountered were picked up by all three dispersal modes, suggesting an overriding effect of plant abundance in the landscapes in which the deer roam, which was also indicated by the statistical analysis. Nonetheless, a significant proportion of species were associated with either gut, fur, or hoof‐borne dispersal, reflecting the effect of plant traits and, potentially, animal behavior. Plant species being dispersed more often than expected through intestines were mainly associated with ruderal habitats, whereas species transported via fur tended toward association with wooded habitats. Considering the increasing red deer populations in Europe, and the differences between seed dispersal modes, all modes of animal seed dispersal should be taken into account in future studies.OPEN RESEARCH BADGES This article has been awarded Open Data and Open Materials Badges. All materials and data are publicly accessible via the Open Science Framework at https://doi.org/10.6084/m9.figshare.7982483 and https://doi.org/10.6084/m9.figshare.7982483

Highlights

Large herbivores have key impacts on vegetation structure and species composition of plant communities (Burns, Collins, & Smith, 2009; Ripple et al, 2015)
We ask: (a) Does seed species composition differ between the three deer‐mediated seed dispersal routes? (b) Can seed traits and whole‐plant traits predict the dispersal route preferentially taken by plant species?
Our study shows that the species composition of plants seeds dispersed by red deer in Denmark, either through the guts or attached to the fur or hooves, differs significantly, especially between internal and external dispersal

Summary

| INTRODUCTION

Large herbivores have key impacts on vegetation structure and species composition of plant communities (Burns, Collins, & Smith, 2009; Ripple et al, 2015). The release height of the diaspores can affect the attachment and retention potential of diaspores in the fur, with seeds presented near the soil surface being less likely to becoming attached to favorable positions on the animal, such as the back (Albert, Auffret, et al, 2015; Graae, 2002; Wessels, Eichberg, Storm, & Schwabe, 2008) It may affect endozoochory, as plant height in general influences in probability of ingestion by both mixed feeders and concentrate selectors (Albert, Mårell, et al, 2015). We ask: (a) Does seed species composition differ between the three deer‐mediated seed dispersal routes (guts, fur, hooves)? (b) Can seed traits and whole‐plant traits predict the dispersal route preferentially taken by plant species?

| MATERIALS AND METHODS

Findings

| DISCUSSION