Megafauna were standard components of most ecosystems (Smith et al 2010 show how body six increased over time). So the current megafauna-poor world in an anomaly. We had elephants everywhere in the late Pleistocene except Australia and Antarctica. He shows a very striking map.
How do megafauna-rich ecosystems function in the temperate zone? Shows artist’s impression of Norfolk in Pleistocene with abundant megafauna. He shows megafauna of the last interglacial in Germany, including lions, elephants, rhinos, hyenas, wild horses, leopards
There has been a big discussion about whether the temperate forest biome was a closed forest, a mosaic, a pasture or a no-analogue system. The paleorecord says that the meso and small biota were largely the same as modern. But the megafauna are gone.
If you try and make a synthesis of the interglacial paleorecord, it says there were many trees in the landscape, but also evidence of more open vegetation (meadow/grassland pollen), plant macro fossils in small forest hollows. Clear signs of open vegetation near rivers, and on poor soil. We had a forest ecosystem but it might have been more heterogeneous than we normally associate with the forest. In the vertebrate fauna you see species of mixed habitats, such as horses, fallow deer and grazing rhino (Dicerorhinus), and grassland small mammals (field voles) and birds as well as woodland species.
There are some outstanding questions:
What were the densities of large herbivores?
How much of the vegetation was closed forest, and how much was open or semi-open?
Recent study by Sandom et al (2014, PNAS) shows herbivores had a positive influence on diversity. Used beetles as indicators - useful for ecosystem reconstruction as many beetles are very specialised in habitat needs. The UK has by far the best record on fossil beetles! This analysis is focussed on the UK.
They look at four periods.
Last interglacial (132-100 kyr) - no evidence of any humans, and certainly before modern humans
Last ice age (50-15 kyr)
Early Holocene (10-5 kyr)
Late Holocene cultural landscape (2-0 kyr)
The look and dung beetles. Pasture dung levels at LIG were as high as cultural landscape (this says high densities of herbivores in LIG)
Woodland dung is high in early Holocene, but lower in LIG
Hence there were often high herbivore densities and mosaic landscape during the LIG. More open vegetation in LIG, more closed forest in the early Holocene. Clearly shows very high species diversity and mosaic landscapes in the LIG. The study is biased towards lowland sites near floodplains
What is the relevancy beyond Europe.
Asia also had high megafaunal diversity in the temperate forest zone (e.g. Japanese elephant and giant deer). Same story in temperate forest zone of North America, and the “temperate” high Andes of Ecuador! (Sanchez et al 2013 PPP). Dung beetles are an underexploited resource for paleoecological studies.
David Nogues-Bravo: could today’s European forests support high densities of megafauna.
Jens-Christian Svenning: I don’t see why not.
How do megafauna-rich ecosystems function in the temperate zone? Shows artist’s impression of Norfolk in Pleistocene with abundant megafauna. He shows megafauna of the last interglacial in Germany, including lions, elephants, rhinos, hyenas, wild horses, leopards
There has been a big discussion about whether the temperate forest biome was a closed forest, a mosaic, a pasture or a no-analogue system. The paleorecord says that the meso and small biota were largely the same as modern. But the megafauna are gone.
If you try and make a synthesis of the interglacial paleorecord, it says there were many trees in the landscape, but also evidence of more open vegetation (meadow/grassland pollen), plant macro fossils in small forest hollows. Clear signs of open vegetation near rivers, and on poor soil. We had a forest ecosystem but it might have been more heterogeneous than we normally associate with the forest. In the vertebrate fauna you see species of mixed habitats, such as horses, fallow deer and grazing rhino (Dicerorhinus), and grassland small mammals (field voles) and birds as well as woodland species.
There are some outstanding questions:
What were the densities of large herbivores?
How much of the vegetation was closed forest, and how much was open or semi-open?
Recent study by Sandom et al (2014, PNAS) shows herbivores had a positive influence on diversity. Used beetles as indicators - useful for ecosystem reconstruction as many beetles are very specialised in habitat needs. The UK has by far the best record on fossil beetles! This analysis is focussed on the UK.
They look at four periods.
Last interglacial (132-100 kyr) - no evidence of any humans, and certainly before modern humans
Last ice age (50-15 kyr)
Early Holocene (10-5 kyr)
Late Holocene cultural landscape (2-0 kyr)
The look and dung beetles. Pasture dung levels at LIG were as high as cultural landscape (this says high densities of herbivores in LIG)
Woodland dung is high in early Holocene, but lower in LIG
Hence there were often high herbivore densities and mosaic landscape during the LIG. More open vegetation in LIG, more closed forest in the early Holocene. Clearly shows very high species diversity and mosaic landscapes in the LIG. The study is biased towards lowland sites near floodplains
What is the relevancy beyond Europe.
Asia also had high megafaunal diversity in the temperate forest zone (e.g. Japanese elephant and giant deer). Same story in temperate forest zone of North America, and the “temperate” high Andes of Ecuador! (Sanchez et al 2013 PPP). Dung beetles are an underexploited resource for paleoecological studies.
David Nogues-Bravo: could today’s European forests support high densities of megafauna.
Jens-Christian Svenning: I don’t see why not.