Mammalian herbivores as potential seed dispersal vectors in ancient woodland fragments

Abstract

Europe's remaining ancient woodland is highly fragmented and many specialist woodland plants persist as isolated relictual populations. Their apparent dispersal limitation and failure to colonise more recently established secondary woodlands may reflect a loss of vectors and mechanisms for dispersal. This is in contrast to long‐distance dispersal events evidenced both by paleoecology and some contemporary observations. Although increasing populations of deer are recognised as important dispersers of plant seeds, particularly for species with no apparent dispersal mechanism, the potential for deer to disperse ancient woodland plants has not been studied previously in the UK, where remaining ancient woodland fragments are frequently surrounded by arable landscapes. Viable seed content of 616 faecal samples collected from a guild of mammalian herbivores; red deer Cervus elaphus, fallow deer Dama dama, roe deer Capreolus capreolus, reeves' muntjac Muntiacus reevesi and brown hare Lepus europaeus, over five months and from four coppiced ancient semi‐natural woodlands in eastern England, was assessed. Following cold stratification and sowing in a controlled greenhouse, 502 seedlings of 41 species germinated. Three species, constituting just 1.8% of the total individual seedlings recorded, were characteristic of woodland habitats, including only one ancient woodland indicator species, wood speedwell Veronica montana. Germinated plant species were instead characteristic of non‐woodland habitats including grassland, arable and ruderal communities. The four most abundant species were the widespread grass common bent Agrostis capillaris, the ruderal greater plantain Plantago major and the two crop species, wheat Triticum spp. and rape Brassica napus. Mammalian herbivory in these ancient woodland fragments provided few dispersal benefits for the woodland plant community. Instead, larger free‐ranging herbivores transported large volumes of propagules of ruderal agrarian and open‐habitat species from surrounding habitats into ancient woodland fragments.