Fig. 4.
Palaeoartistic reconstructions of Last Interglacial landscapes in the European temperate forest biome, consistent with our pollen-based estimates of vegetation structure.
Typical Last Interglacial fauna are shown, such as the extinct straight-tusked elephant (Palaeoloxodon antiquus), an extinct rhinoceros (Stephanorhinus kirchbergensis), and aurochs (Bos primigenius, the extinct wild form of contemporary domestic and feral cattle), alongside common extant species: fallow deer (Dama dama), a great spotted woodpecker (Dendrocopos major), a European robin (Erithacus rubecula), and greylag geese (Anser anser). (Top left) Early-temperate period: Light woodland, including a mix of taller trees and the shrub hazel (Corylus avellana), and grass-dominated open vegetation. (Top right) Early-temperate period: Open, grassy vegetation interspersed with light woodland and bordering closed forest with shade-tolerant trees. (Bottom left) Late-temperate period: Light woodland, denser forest with frequent hornbeam (Carpinus betulus), and some open vegetation (front). (Bottom right) Late-temperate period: Open grass- and sedge-dominated vegetation with free-standing deciduous oaks (Quercus robur), with more closed tree stands in the background.
Palaeoartistic reconstructions of Last Interglacial landscapes in the European temperate forest biome, consistent with our pollen-based estimates of vegetation structure.
Typical Last Interglacial fauna are shown, such as the extinct straight-tusked elephant (Palaeoloxodon antiquus), an extinct rhinoceros (Stephanorhinus kirchbergensis), and aurochs (Bos primigenius, the extinct wild form of contemporary domestic and feral cattle), alongside common extant species: fallow deer (Dama dama), a great spotted woodpecker (Dendrocopos major), a European robin (Erithacus rubecula), and greylag geese (Anser anser). (Top left) Early-temperate period: Light woodland, including a mix of taller trees and the shrub hazel (Corylus avellana), and grass-dominated open vegetation. (Top right) Early-temperate period: Open, grassy vegetation interspersed with light woodland and bordering closed forest with shade-tolerant trees. (Bottom left) Late-temperate period: Light woodland, denser forest with frequent hornbeam (Carpinus betulus), and some open vegetation (front). (Bottom right) Late-temperate period: Open grass- and sedge-dominated vegetation with free-standing deciduous oaks (Quercus robur), with more closed tree stands in the background.
Illustrator: Brennan Stokkermans.
Pearce, E. A.; Mazier, F.; Normand, S., et al. (2023) (CC BY 4.0)
Pearce, E. A.; Mazier, F.; Normand, S., et al. (2023) (CC BY 4.0)
Researchers led by Elena A. Pearce of the Department of Biology, Aarhus University, Aarhus, Denmark, have looked again at the evidence for the flora and fauna of Europe during the last interglacial period (130,000 -150,000 years ago) and believe they have shown that the previous assumption that Europe was covered in dense woodland prior to the arrival of modern human, may be wrong. Europe was, instead, "full of variation. Importantly, the landscapes harboured large amounts of open and semi-open vegetation with shrubs, light-demanding trees and herbs alongside stands of tall-growing shade trees."
When was the last interglacial period in Europe and what caused it? The last interglacial period in Europe occurred during the Pleistocene epoch, specifically the Eemian interglacial. The Eemian interglacial is estimated to have occurred roughly between 130,000 and 115,000 years ago. It was a relatively warm period when temperatures were higher than during the subsequent Last Glacial Maximum.The team arrived at their conclusion after examining pollen grains from soil samples taken from large parts of Europe.
The primary cause of glacial-interglacial cycles, including the Eemian interglacial, is believed to be variations in Earth's orbit and axial tilt, collectively known as Milankovitch cycles. These variations influence the amount and distribution of solar radiation reaching the Earth's surface. The interplay of these orbital parameters results in periodic changes in climate, leading to alternating glacial and interglacial periods.
During interglacial periods, such as the Eemian, temperatures were warmer, and ice sheets and glaciers retreated. This warmer climate allowed for the expansion of forests and the development of different ecosystems compared to the colder glacial periods. It's important to note that natural climate variability, driven by factors like Milankovitch cycles, played a significant role in past climate changes, but contemporary climate change is also influenced by human activities, particularly the emission of greenhouse gases.
What pollen can reveal about the past
Almost all trees, flowers and shrubs give off pollen. Pollen is to plants what sperm cells are to animals. In order for a plant to seed, its egg cells must be pollinated.
Pollen is spread by the wind or by insects.
A lot of pollen lands on the ground, where it cannot pollinate other plants. Instead, it is eaten by insects or degraded by microorganisms. However, a small amount of pollen lands in lakes, bogs or streams, where it falls to the seabed.
Below the surface, there is often no oxygen and no life, and the pollen is preserved over hundreds of thousands of years in the soil layers.
By looking at the composition of different types of pollen in the soil layers of ancient, buried wetlands, researchers can deduce what the vegetation looked like more than 100,000 years ago.
What they found is explained in the news release from Aarhus University:
Almost all trees, flowers and shrubs give off pollen. Pollen is to plants what sperm cells are to animals. In order for a plant to seed, its egg cells must be pollinated.
Pollen is spread by the wind or by insects.
A lot of pollen lands on the ground, where it cannot pollinate other plants. Instead, it is eaten by insects or degraded by microorganisms. However, a small amount of pollen lands in lakes, bogs or streams, where it falls to the seabed.
Below the surface, there is often no oxygen and no life, and the pollen is preserved over hundreds of thousands of years in the soil layers.
By looking at the composition of different types of pollen in the soil layers of ancient, buried wetlands, researchers can deduce what the vegetation looked like more than 100,000 years ago.
Ancient pollen samples reveal what nature was likeThe researchers have published their findings, open access, in Science Advances, together with some rather nice paintings depicting Europe during the last interglacial:
Samples of ancient pollen helped the research team identify which plants grew more than 100,000 years ago in the last interglacial period.
The research group integrated data from pollen samples from large parts of Europe. The samples reveal that plants that do not thrive in dense forest often constituted large components of the vegetation.
“Tall-growing shade trees like spruce, linden, beech and hornbeam will be most prevalent in dense forests. However, the results show that hazel often covered large areas of the landscapes. Hazel is a bush that doesn’t grow in large quantities in dense forest,” says Jens-Christian Svenning.
In the world of plants, competition for sunlight is fierce. The trees that reach highest with their crowns can capture the most sunlight and win that competition. In beech forests, trees take almost all the sunlight. This means that other, smaller trees and shrubs, such as hazel, cannot grow in a beech forest.
“Hazel thrives in the open countryside and in open or disturbed forest and tolerates disturbance from large animals. Whereas species like beech and spruce often are severely damaged or killed by cutting or browsing, hazel can manage without problems. Even if you cut down a hazel, it will still produce lots of new shoots,” he says.
“For this reason, hazel was often very common in historical coppice woodlands”.
Merck's rhinoceros with pollen between its teeth
There are many indications that large animals kept the landscape varied before humans came, with large areas of open and semi-open vegetation.
A very special study from Poland further underlines this theory, says Jens-Christian Svenning.
"In Poland, researchers have taken a closer look at fossils from Merck’s rhinoceros to see what this large animal lived on. They found remnants of pollen and twigs between its teeth, and when they analysed them, they could see that a large amount came from hazel,” he says and continues:
“So the rhinoceros has trudged around eating branches and leaves from hazel bushes. This supports the theory that the large animals have affected the vegetation, perhaps just like historical coppice woodlands. At the same time, marks of its teeth suggest it had foraged a lot on grass and sedges through its life time.”
AbstractYou know, it’s a constant source of amazement, just how much history occurred in that vast amount of time before creationism's god decided to create the Universe out of nothing by magic.
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.
Big animals, like the elephants on the illustration, probably helped keep part of the European landscape open or semi-open during last interglacial period. That created variation in the vegetation and fauna.
The landscape in Europe was dominated by a variety of different vegetational systems. In this picture it is open wood which lets enough sunlight through the foliage to support bushes, small trees and grasses.
Merck's rhino was one of the animals that loved to feed on hazel leaves. The animal lived in most of Europe and probably played an important function in keeping the landscapes open and varied.
Aurochs are taking a rest in a semi-open forest. The big animals probably meant that these areas didn't grow over.Artwork: Brennan StokkermanPearce, E. A.; Mazier, F.; Normand, S., et al.,
Substantial light woodland and open vegetation characterized the temperate forest biome before Homo sapiens
Science Advances, 9(45) eadi9135. DOI: 10.1126/sciadv.adi9135.
Copyright: © 2023 The authors.
Published by American Association for the Advancement of Science. Open access.
Reprinted under a Creative Commons Attribution 4.0 International license (CC BY 4.0)
In this case, whole ecosystems had arisen in Europe between periods of glaciation, much of it before modern humans, who hadn't been created yet, were still to migrate out of Africa where they had been evolving for about 6 million years.
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