Martine Couvreur

Large herbivores as mobile links between isolated nature reserves through adhesive seed dispersal

Abstract Question: Do large herbivores contribute to the dispersal of plant seeds between isolated habitats by epizoochory? Location: Nature reserves in Flanders, Belgium. Methods: Epizoochory was studied by brushing plant seeds from the fur of 201 domesticated large herbivores (Galloway cattle, donkeys and horses), grazing in 27 Flemish nature reserves. Several herbivores were examined after transport between different nature reserves as part of the seasonal grazing system in Flanders, allowing detection of seed dispersal both within and between reserves. The seedling emergence method was used to identify the dispersed plant species. Results: In total, 6385 epizoochorous seeds from 75 species germinated, yet the real seed quantity was underestimated by the seedling emergence method. A wide variety of seed morphology, seed weights and plant heights was represented among the dispersed species, many of which had a transient seed bank. There was a gradual turnover in epizoochorous species composition in the course of the vegetation season, and seed dispersal occurred both within and between different nature reserves. Conclusions: Domesticated large herbivores, as models for wild mammals in the present and the past, are important dispersers of many plant species. Through seasonal grazing, the herbivores function as ‘mobile link organisms’, connecting isolated nature reserves through seed dispersal, possibly influencing vegetation development and long-term survival of plant populations. As such, large herbivores are important instruments in ecological restoration, especially in fragmented ecosystems. Nomenclature: Lambinon et al. (1998).

An experimental assessment of seed adhesivity on animal furs

Epizoochory is widely recognized as an effective longdistance seed dispersal mechanism. Nevertheless, few studies have focused on the investigation of its influencing factors. One of the key aspects of epizoochory is the adhesive interaction between seeds and furs. We describe a new method to quantify experimentally and standardize the adhesivity of seeds to animal fur, as a measure of epizoochorous dispersal potential. The method excludes the impact of animal behaviour and environmental factors, and allows the ranking of species according to their adhesivity score. We measured adhesivity scores for 66 species on the furs of seven mammals. Deep furs with long, rough, undulated hairs implanted at a large angle were most suited for seed adhesion, while seeds adhered less well to shallow furs with short, smooth, straight hairs implanted at small angles. Seeds with specialized adhesive appendages had higher adhesivity scores than seeds with unspecialized appendages and seeds without appendages. However, an interaction effect between certain seed and fur types exists. Although seed morphology is a good predictor for seed adhesivity on fur, less well-adhering seed types often still have relatively high adhesivity scores. Therefore, it is likely that nearly all species are, to some extent, able to disperse epizoochorously.