When large herbivores became less abundant, fewer young trees and shrubs were eaten or damaged, making it easier for woody vegetation to spread. That is a well-supported contributor to post-megafauna tree-cover expansion across humid-temperate Europe, but it is not a complete, Scandinavia-specific explanation: climate, fire and human activity also shaped forests, and the available evidence does not pin down how the process varied across Norway, Sweden and Denmark.
How large grazers kept some places open
Large herbivores affect vegetation in more ways than eating grass. Browsing removes shoots and seedlings; grazing reduces ground vegetation; and trampling, debarking and rooting disturb plants and soils. When these pressures are frequent, fewer young trees survive to form a canopy. When pressure eases, more seedlings can establish and woodland can spread.
This does not mean that grazers kept all ancient landscapes treeless. Their effects varied with animal numbers, plant communities and local conditions. The result could be a shifting mosaic of open ground, lightly wooded patches and denser forest, rather than either uninterrupted forest or an entirely open landscape. A 2026 review of humid-temperate Europe argues for this mosaic view and reports tree-cover expansion after the Late-Pleistocene megafaunal collapse under reduced herbivore pressure (Czyżewski et al., Revisiting Europe’s temperate forests).
What the evidence says—and what it cannot prove
A broad European synthesis
The 2026 review brings together several kinds of evidence, including pollen, plant macrofossils, isotopes, dental ecometrics, microcharcoal and ancient environmental DNA. Its conclusion is that tree cover expanded after megafauna declined, in association with reduced herbivore pressure. Because the review covers humid-temperate Europe rather than resolving a separate chronology for Scandinavia, it supports the mechanism and broad pattern—not a precise account of when or how strongly forests changed in each Scandinavian country.
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Pollen comparisons point to disturbance, not a single cause
A 2024 study compared pollen-based vegetation reconstructions from the Last Interglacial (129,000–116,000 years before present) with those from the early–mid-Holocene (8,700–5,700 years before present). It found more hazel (Corylus) and yew (Taxus) in the Last Interglacial reconstructions, while oak (Quercus) was moderately abundant in both periods. The authors interpret the contrast as consistent with different disturbance regimes and possible herbivore influence, but say a direct quantitative link has not been established (Pearce et al., Journal of Ecology, 2024). Pollen patterns therefore inform the explanation; they are not a controlled test proving that herbivores alone caused the difference.
Why fewer grazers were not the only reason forests changed
| Influence | How it can shape woodland | What the evidence supports |
|---|---|---|
| Herbivores | Browsing, grazing and physical disturbance can limit tree recruitment and create open patches. | The 2026 European review associates post-megafauna tree-cover expansion with reduced herbivore pressure; the strength and timing of that effect in Scandinavia are not resolved. |
| Climate and moisture | Temperature and water availability affect which trees can grow and how quickly vegetation develops. | They are among the forces shaping the outcome; the available evidence does not isolate their regional contribution for Scandinavia. |
| Fire | Fire can open woodland and alter which plants regenerate. | Palaeoecological evidence includes charcoal records, and fire is one of several processes that can maintain openness. |
| Human activity and livestock | Hunting, burning and later land use change vegetation; domestic herbivores can restore some grazing and browsing effects while introducing new pressures. | Human influence increased from the Mesolithic onward, and later domestic herbivory added to, rather than simply copied, earlier disturbance dynamics. |
These influences overlap: an opening created by fire or human land use may respond differently to herbivory than a wetter or drier woodland. In a 2005 discussion of European primeval forests, Mitchell also noted that fire, windthrow and seasonal flooding can produce open woodland. Mid-Holocene evidence from Zealand showed abundant oak and hazel after aurochs and elk had been extirpated, while other large herbivores remained. That example is a useful warning against treating the loss of any one group of grazers as a complete explanation (Mitchell, Journal of Ecology, 2005).
Forest change continued long after megafauna declined
Forest history did not stop with the Late-Pleistocene transition. A 2018 pollen-based synthesis describes early-Holocene forest expansion to a maximum, followed by gradual decline in the second half of the Holocene. It estimates modern boreal forest cover at around 55–60% in its regional reconstruction, after a relatively rapid decline from about 1,700 years before present in the context of rising human impact in northern Europe. That is a synthesis estimate for the boreal region—not a current measurement for all of Scandinavia (“Europe’s lost forests,” 2018).
A later local example from southern Sweden
At Söderåsen in southern Sweden, a study using pollen, plant macrofossils and tree-ring evidence reports renewed, rapid forest expansion after grazing pressure declined around 1900 CE (Rundgren et al., The Holocene, 2025). This historical case shows that reduced grazing can accompany forest recovery in a particular place. It is not direct evidence for the ancient transition: it concerns a different period, landscape and human context.
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What to conclude about Scandinavia
The best-supported answer is that fewer large herbivores likely removed one important check on tree growth, allowing woodland to expand in parts of Europe. But the evidence presented here does not establish a single Scandinavian timeline or show that megafauna loss alone drove forest expansion across the region. Climate, fire and human land use also mattered, and the historical Swedish example demonstrates a mechanism—not a substitute for evidence about the Late Pleistocene.
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