Enhancement of local species richness in tundra by seed dispersal through guts of muskox and barnacle goose

Abstract

The potential contribution of vertebrate-mediated seed rain to the maintenance of plant community richness in a High Arctic ecosystem was investigated. We analyzed viable seed content in dung of the four numerically most important terrestrial vertebrates in Northeast Greenland - muskox (Ovibos moschatus), barnacle goose (Branta leucopsis), Arctic fox (Alopex lagopus) and Arctic hare (Lepus arcticus). High numbers of plant propagules were found in the dung of muskox and barnacle goose. Seeds of many plant species were found in the faeces of one vertebrate species only. Propagule composition in barnacle goose droppings was relatively uniform over samples, with a high abundance of the nutritious bulbils of Polygonum viviparum (Bistorta vivipara), suggesting that geese have a narrow habitat preference and feed selectively. Propagule composition in muskox dung was diverse and heterogeneous among samples, suggesting a generalist approach in terms of food selection and the haphazard ingestion of plant propagules with foliage. The species composition of plant propagules in dung samples was different from that of the receiving plant communities (in terms of the Sørensen and Czekanowski dissimilarity indices), and dung deposition, especially by muskox, often brought new species to the receiving community. The results suggest that endozoochorous propagule dispersal in the Arctic has a great potential in the generation and maintenance of local species richness, albeit being little specialized. It is further suggested that endozoochory is an important means of long-distance dispersal and, thereby, of plant migration in response to climate change.

First evidence of bryophyte diaspores in the plumage of transequatorial migrant birds

“…The feasibility of avian mediated endozoochory in the LDD of aquatic invertebrates and seed plants is well supported by diaspore retention times in captive birds and the survival of ingested diaspores (Proctor, 1968; Figuerola & Green, 2002) as well as the recovery of viable seeds from the dung of wild birds (Bruun, Lundgren & Philipp, 2008). Based on experimentally derived retention times and viability estimates paired with migratory movement data, modeling of potential dispersal distances supports intercontinental-scale movement of aquatic organisms and seeds (Viana et al, 2013).…”

Ontogenetic niche shifts in threeVacciniumspecies on a sub-alpine mountain side

“…Each fruit contains, on average, around 25 seeds for V. myrtillus and V. uliginosum, and 11 for V. vitis-idaea (Eriksson and Ehrlén 1991), and these are widely dispersed after ingestion and defecation by a number of mammal and bird species (Traveset and Willson 1997;Graae et al 2004;Bruun et al 2008). Seeds should therefore be well dispersed throughout the landscape, allowing potential recruitment in different communities.…”

“…Traveset and Willson 1997;Graae et al 2004;Bruun et al 2008), and can remain viable after several years of burial (Granström 1987;Hill and Vander Kloet 2005). Despite this, they lack germinable seed banks across much of their geographical range (Vander Kloet and Hill 1994;Molau and Larsson 2000;Alsos et al 2003;Cooper et al 2004; but see Granström 1982).…”

Hares promote seed dispersal and seedling establishment after volcanic eruptions

“…The Arctic hare (Lepus arcticus) has food preferences among Arctic plants and reduces seed viability through long gut passage times (Bruun et al, 2008), and the European hare (Lepus europaeus) is less important to local seed dispersal because it reduces seed germinability (Chang et al, 2005). These results suggest that the hares on Mount Koma feed on large numbers of G. miqueliana fruits.…”