Substantial light woodland and open vegetation characterized the temperate forest biome before Homo sapiens

• The extent of vegetation openness in past European landscapes is widely debated. In particular, the temperate forest biome has traditionally been defined as dense, closed-canopy forest; however, some argue that large herbivores maintained greater openness or even wood-pasture conditions. Here, we address this question for the Last Interglacial period (129,000–116,000 years ago), before Homo sapiens–linked megafauna declines and anthropogenic landscape transformation. We applied the vegetation reconstruction method REVEALS to 96 Last Interglacial pollen records. We found that light woodland and open vegetation represented, on average, more than 50% cover during this period. The degree of openness was highly variable and only partially linked to climatic factors, indicating the importance of natural disturbance regimes. Our results show that the temperate forest biome was historically heterogeneous rather than uniformly dense, which is consistent with the dependency of much of contemporary European biodiversity on open vegetation and light woodland.

• The extent of vegetation openness in the temperate forest biome prior to modern humans is widely debated – particularly in Europe regarding baselines for conservation and restoration. The temperate forest biome was traditionally thought to be dense closed-canopy forest; however, this view has been challenged by arguments that large herbivores could have maintained some degree of openness, or even widespread wood pasture-like conditions. In this study, we address this question for the Last Interglacial (Eemian; 129,000 – 116,000 years ago) in Europe – prior to major human-driven defaunation and large-scale anthropogenic landscape transformation. We applied the landscape reconstruction method REVEALS to 96 Last Interglacial pollen4records. We found that there was substantial open and light woodland vegetation across Europe. Within the temperate forest biome, open taxa on average represented 19% of the vegetation cover in Mesocratic I, and 16% in Mesocratic II (early and late parts of the core of the interglacial, respectively), with light woodland vegetation covering an additional 60% in Mesocratic I and 34% in Mesocratic II. The degree of openness was highly variable and not well explained by environmental or climatic factors. Overall, we found much larger proportions of openness than expected under modern succession models, pointing to the importance of natural disturbance factors such as large herbivores, fires, or flooding. Our results show that the temperate forest biome was historically heterogeneous in vegetation structure, rather than uniformly dense, explaining why a large proportion of European biodiversity depends on open vegetation and light woodland habitats.

Ämnesord

NATURVETENSKAP  -- Biologi -- Ekologi (hsv//swe)

NATURAL SCIENCES  -- Biological Sciences -- Ecology (hsv//eng)

NATURVETENSKAP  -- Geovetenskap och miljövetenskap -- Klimatforskning (hsv//swe)

NATURAL SCIENCES  -- Earth and Related Environmental Sciences -- Climate Research (hsv//eng)

NATURVETENSKAP  -- Geovetenskap och miljövetenskap -- Naturgeografi (hsv//swe)

NATURAL SCIENCES  -- Earth and Related Environmental Sciences -- Physical Geography (hsv//eng)

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