Where The Wild Things Were: Re-wilding and the Sixth Extinction - Biodiversity Conservation and Environmental Change - page 44

Table 3.2 Early Holocene herbivores in Europe, suggesting less herbivore pressure in Ireland,
compared with Britain and north-west Europe (Mitchell 2005)

Species Europe Britain Ireland

Aurochs (Bos primigenius) X X

Beaver (Castor fibre) X X

Bison (Bison spp.) X

Elk (Alces alces) X X

Fallow deer (Dama dama) X

Horse (Equus caballus s.l.) X X

Red deer (Cervus elaphus) X X X

Reindeer (Rangifer tarandus) X X

Roe deer (Capreolus capreolus) X X

Wild boar (Sus scrofa) X X X

Does Mitchell's study really mean the end of the wood-pasture hypothesis? (Birks 2005)
Mitchell's argument rests on the assumption that Ireland is effectively a grazing exclosure,
whereas in fact red deer were present, and studies of current forest dynamics show that deer
have signiicant efects on tree recruitment and forest structure and composition (Baranˇeková
et al. 2007, Gill and Morgan 2010, Kuijper et al. 2010). Furthermore, Mitchell was generous in
allocating forests to closed canopy status; prior to his work, palaeoecologists generally inter-
preted 90-95% tree pollen as closed canopy 'wildwood' (Smith et al. 2010), whereas he classi-
fied sites with over 60% of tree pollen as closed canopy forest
Given that natural senescence and death of trees, fire, and windthrow all disturb forest
canopies, it seems likely that open elements are natural components of most European for-
ests, but that their prevalence fluctuated depending on changing climate, fire, herbivory, and
human management. Whether herbivores create or simply maintain these open areas is still
a matter of debate, and fire may have been a primary or complementary driver of forest
dynamics in some ecosystems (Bradshaw et al. 2003, Rackham 2003) but there is no doubt
that herbivores were present in substantial numbers in the last interglacial and were associ-
ated with more open canopy structure (Sandom et al. 2014). It might be that the higher preva-
lence of closed forests of the early Holocene was a result of megafaunal attrition and the
return to more open canopy structure that followed more intensive human management is
well within the range of natural forest variability.
Human management is evident in European forests from the mid-Holocene, in some cases
increasing heterogeneity and habitat for light demanding taxa through mechanical clear-
ance, grazing and fire (see Chapters 4 and 6) (Tipping et al. 1999, Gil-Romera et al. 2010,