Wood-pasture hypothesis

While his proposals for widespread semi-open savanna as the predominant landscape of temperate Europe in the early to mid-Holocene have at large been rejected, they do partially agree with the established wisdom about vegetation structure during previous interglacials.

Whether the Holocene prior to the rise of agriculture provides an adequate approximation to a state of "pristine nature" at all has also been questioned, since by that time anatomically modern humans had already been omnipresent in Europe for millennia, with in all likelihood profound effects on the environment.

The severe loss of megafauna at the end of the Pleistocene and beginning of the Holocene known as the Quaternary extinction event, which is frequently linked to human activities, did not leave Europe unscathed and brought about a profound change in the European large mammal assemblage and thus ecosystems as a whole, which probably also affected vegetation patterns.

[8] In his 1817 work Anweisungen zum Waldbau (Directions for Silviculture), Heinrich Cotta posited that if humans abandoned his native Germany, in the space of 100 years it would be "covered with wood".

[9] This assumption laid the foundation for what is now called the high-forest theory, which assumes that deciduous forests are the naturally predominant ecosystem type in the temperate, broad-leaved regions.

This, however, did not change anything about the status of the "high-forest theory" as the commonly accepted view; that without human intervention closed-canopy forest would dominate the global temperate regions as the potential natural vegetation.

[36][38] In regions with relatively intact large-mammal assemblages in Africa and Asia, as well as in European rewilding areas where "naturalistic grazing" is practised, herbivore biomass exceeds the values commonly deemed appropriate for temperate forests many times over.

Backbreeding-projects, such as the German Taurus project and the Dutch Tauros programme are addressing this issue by breeding domestic cattle that can be released into the landscape as hardy and sufficiently similar proxies to act as ecological replacements for the aurochs.

Indeed, investigations point to at least locally open circumstances, for example in floodplains, on infertile soils, chalklands and in submediterranean and continental areas, but maintain that forest largely dominated.

[3][26] On the other hand, traditional animal husbandry may have mitigated the effects of possibly human-induced megafaunal die-off, allowing the survival of species of the open landscape previously created and maintained by megafauna.

He argues that the only explanation for the great abundance of oak and hazel pollen in previous ages is that the primeval landscape was open, and this contrast forms the principal theorem of his hypothesis.

These were multifunctional and used for a range of purposes, from pannage and livestock grazing to the harvest of tree hay, coppice, timber and oak galls for the manufacture of ink, as well as for the production of charcoal, crops and fruit.

[69]In line with this, it may be argued that the prevalence of closed-canopy forest as the prevailing conservation narrative in Europe similarly arises from multiple shifted baselines: However, a strong argument that may put Vera's etymological evidence into perspective altogether is that the composition of medieval woodlands may not be relevant to their naturalness.

[85] There are several ecological processes at work in herbivore grazing systems, namely associational resistance, shifting mosaics, cyclic succession, and gap dynamics.

[89] On the other hand, nut-bearing species such as hazel, beech, chestnut, pedunculate and sessile oak would become "planted" somewhat deliberately in the vicinity of those shrubs by rodents such as red squirrel and wood mouse, the nuthatch and corvids such as crows, magpies, ravens and especially jays, which store them for winter supply.

[94] Thorny bushes play an important role in tree regeneration in the European lowlands,[95] and evidence is emerging that similar processes can also ensure the survival of browsing-sensitive species like rowan in browsed boreal forests.

Therefore, once the established trees would start to decay, either due to old age or other factors like pathogens, illness, lightning strike or windbreak, this would leave open, bare land behind, for grasses and unpalatable species to colonise, closing the cycle.

[3][26] Modern humans have likely exerted a strong influence in Europe since their first appearance here during the Weichselian glaciation, which has led some researchers to criticize Vera's choice of the early to mid Holocene as his benchmark for pristine nature.

[103] Both groups of animals spread and retreated cyclically, depending on whether the climate favoured one or the other, but essentially remained intact in refugia that continued to provide the conditions they preferred.

Modern taxa with a once wider distribution include the Eurasian saiga, wapiti-deer, the Asian black bear, bisons, the dhole, lions, the leopard, the jaguar, and the giant anteater.

Research has also shown that the extant megafaunal species that survived the extinction event experienced a sharp population decline starting at the same time and continuing to the present day.

[110] While the exact cause of these events remains debated, it seems clear that ecological niches in Europe, the Middle East, big parts of Asia, and the Americas were left unoccupied.

[54] Similarly, modelling approaches[121] and the use of beetle diversity as an indicator for landscape openness[3] also support the view of a predominance of forest throughout the early and middle Holocene in most of Europe.

The aurochs at least seems to have favoured fertile, low-lying riverine areas and plains,[123] which may have led to locally open conditions, while the hill and mountain ranges were more heavily forested.

[131][132] In a 2014 paper, rewilding ecologist Christopher Sandom et al. found that the depauperate megafauna that remained in Europe after these extinctions may be the reason for the reduced landscape openness.

Instead it was believed that the broadleaved regions were dominated by climax communities of shade-tolerant species, interrupted only occasionally by collapses of forest cover and disturbances through fire, storm or browsing.

[138] Similarly high numbers were counted at other locations in Eastern Europe, making the region one of the hotspots for plant species richness on small scale worldwide.

[142][143] For Europe, studies have demonstrated the local persistence of grasslands throughout the Holocene as natural ecosystems,[136][52] the important role they play for insects, for example,[144][145] and the potential for biodiversity enhancement that lies in their maintenance by reintroduced large herbivores.

Taking them into account, it works to establish free-moving herds of European bison, aurochs-proxies (e.g. Tauros-cattle), proxies for the wild tarpan (e.g. Konik, Exmoor pony) as well as water buffalo and kulan (which were present in Europe until the early Holocene)[f] to create dynamic ecosystems maintained by the grazing and browsing activity of these herbivores.

This goes hand-in-hand with the fact that, for instance, 63 of the ecosystems listed in Annex I of the Habitats Directive of the European Union strictly depend on low-intensity use and maintenance work, mostly in the form of grazing and mowing.

The image shows the succession from bare land to forest in 6 phases. Each phase is characterised by the prominence of one feature; bare soil decreases as vegetation increases. Mosses and annuals are outcompeted by grasses and perennials, which give rise to woody pioneers, then fast-growing trees and eventually the climax community. Simultaneously, the disturbance through fire, storm or antropogenic factors decreases steadily, while biodiversity, the soil layer and total biomass increases following a flat curve
The natural succession in the temperate hemisphere as per the high-forest theory, and the characteristics associated with each phase.
Old-growth beech forest in Biogradska Gora National Park, Montenegro
If the high-forest theory holds true, beech forests would naturally dominate temperate Europe.
Mature red deer stag in a pasture near an oak tree
Red deer can prevent the regeneration of forest. Whether this is seen as negative or positive may depend on both the conditions and the eye of the beholder.
African savanna. Trees in the background, grassland in the foreground, wildebeest crossing
In how far African savannas are adequate to draw comparisons to the primeval European landscape remains debated.
Pollen from plants that are pollinated by insects, such as here Zilla Spinosa by a dwarf honey bee , rarely or never ends up in places that favour preservation, such as lakeshores. It is therefore generally underrepresented in pollen deposits.
Reclining female lion looks directly toward camera
An example of a shifted baseline: Asiatic lions were present in the Balkans well into Classical Antiquity , yet few would consider them native to Europe. (Pictured: An Asiatic lioness in India's Gir National Park .)
Old beeches in a forest. The structure with a thick trunk and proportionally thin branches is reminiscient of a use as pollards
Many European forests were formerly managed as wood-pasture, coppice or were, as in this case, pollarded .
Young hawthorn shrub, heavily browsed upon by cattle and therefore shaped. A young dogwood bush inside benefits from the hawthorn's thorn protection.
The four phases of vegetation succession according to the hypothesis: In the park phase, grassland and heath prevail. In the scrub phase they get invaded by thorny shrubs, which in turn provide protection for tree saplings. Then, in the grove phase, the saplings grow up and displace the nurse bushes. Eventually, in the break-up phase, the trees start to die, the groves thin out and grassland species return.
Collage of mixed temperate forest environments in Europe during the Eemian. Animals clockwise: fallow deer , straight-tusked elephants , Merck's rhinoceros and aurochs .
Late Pleistocene distribution of the woolly mammoth, marking the extension of the mammoth steppe.
Atlatls have been used in Europe since at least the late Upper Palaeolithic and were effective weapons for killing large, thick-skinned prey.
Life restoration of two straight-tusked elephants during the Eemian interglacial. Palaeoecological data suggest that the European megafauna may prehistorically have created a mosaic landscape in the temperate zone.
The Sonian Forest in Belgium as an example of a protected closed-canopy beech forest .
Taurus cattle in the Lippeaue , serving as proxies for the aurochs.
Wisent herd in Milovice Nature Reserve , Czech Republic .
Dehesa/montado , a very species-rich, semi-natural wood-pasture landscape type of the Iberian peninsula .
A young oak utilises an established juniper bush as protection against browsing in a historical wood-pasture.
Modern remains of the mammoth steppe, still found at scattered sites in Siberia , can serve as a model for larger-scale restoration.