A 6000 ha reserve was created on land reclaimed from the sea. Greylag geese arrived and settled the new land. Through their grazing the facilitated many other species - they were keystone species. The geese and dynamic water table drive succession (not respond to succession)
The geese’s complete biotope is the marsh and grassland combined.
Then he introduced wild cattle to maintain the grassland. Critics said wild ungulates create a closed canopy reserve. Two large herbivores went extinct auroch 1627 and tarpan 1850. Grazing guild completely vanished. Other herbivores became functionally extinct.
The closed canopy forest is an incorrect baseline of the natural vegetation in Europe. But cattle prevent the regeneration of trees in a forest. The conclusion is that a wood pasture is a degraded ecosystem. If nature is to be restored you have to remove the cattle. And extant ungulates need to be culled to low levels. All the wood pastures changed into closed canopy forests. These closed canopy forests of Germany are called the new primeval forests of the future. In the former wood pastures oak and other light demanding tree species disappeared within decades. He shows forest structure graphs for 4 species in a national park in Denmark. In the park, 50% of all vascular plants disappeared within 40 years (the light demanding species)
In the wood pasture we see a mantle and fringe vegetation of sloe/blackthorn (Prunus spinosa). Within it there are everywhere young oaks within this fringe. The oaks are planted by the jay hoarding acorns. The regeneration of trees in a wood pasture is in the mantle fringe. When you have hawthorn they also nurse an oak. Hazel is a a light demansing shrub planted in the sloe by the nut hatch. The end result is climbs of trees surrounded by a scrub; a grove. A very diverse landscape driven by grazing animals (Bakker et al 2004).
In a closed canopy forest the sloe is disappearing. There is no shrub layer. Forest-grown trees with narrow crowns because they compete for light. When trees dies the slow occupies the gaps and the grove retreats.
You don’t need elephants to open up a forest. The wood pasture is a non-linear cyclical succession
He argues that cycling wood pastures are the natural early Holocene ecosystem of Europe. Sloe is insect-pollinated so not visible in record. Also, grazed grasses rarely flower so no pollen. If it does flower it is in the mantle vegetation so is not wind-spread. Only tree pollen appears in the long term records, giving a false impression of closed-canopy forest.
Saproxylic beetles demonstrate that there were large, open grown trees
Back to the Netherlands hypothesis. The herbivores introduced were regulated bottom up by the amount of food. There is no such thing as a carrying capacity - every year is different.
The false baseline is that herbivores must have been in very low densities otherwise there could not be a forest. So bison and red deer numbers are kept at too low a density. A wrong theory can cause an overkill. Bison are an IUCN red list species yet are still shot to maintain low densities.
Sprint shrubs became established at high deer densities
In the Holocene large herbivores are keystone species and drivers of the natural succession.
Vera’s hypothesis explained here:
http://onlinelibrary.wiley.com/doi/10.1111/j.1365-2745.2004.00964.x/abstract
http://www.knepp.co.uk/Other_docs/Frans%20Vera/Birks%20over%20Vera%20in%20TREE1.pdf
The geese’s complete biotope is the marsh and grassland combined.
Then he introduced wild cattle to maintain the grassland. Critics said wild ungulates create a closed canopy reserve. Two large herbivores went extinct auroch 1627 and tarpan 1850. Grazing guild completely vanished. Other herbivores became functionally extinct.
The closed canopy forest is an incorrect baseline of the natural vegetation in Europe. But cattle prevent the regeneration of trees in a forest. The conclusion is that a wood pasture is a degraded ecosystem. If nature is to be restored you have to remove the cattle. And extant ungulates need to be culled to low levels. All the wood pastures changed into closed canopy forests. These closed canopy forests of Germany are called the new primeval forests of the future. In the former wood pastures oak and other light demanding tree species disappeared within decades. He shows forest structure graphs for 4 species in a national park in Denmark. In the park, 50% of all vascular plants disappeared within 40 years (the light demanding species)
In the wood pasture we see a mantle and fringe vegetation of sloe/blackthorn (Prunus spinosa). Within it there are everywhere young oaks within this fringe. The oaks are planted by the jay hoarding acorns. The regeneration of trees in a wood pasture is in the mantle fringe. When you have hawthorn they also nurse an oak. Hazel is a a light demansing shrub planted in the sloe by the nut hatch. The end result is climbs of trees surrounded by a scrub; a grove. A very diverse landscape driven by grazing animals (Bakker et al 2004).
In a closed canopy forest the sloe is disappearing. There is no shrub layer. Forest-grown trees with narrow crowns because they compete for light. When trees dies the slow occupies the gaps and the grove retreats.
You don’t need elephants to open up a forest. The wood pasture is a non-linear cyclical succession
He argues that cycling wood pastures are the natural early Holocene ecosystem of Europe. Sloe is insect-pollinated so not visible in record. Also, grazed grasses rarely flower so no pollen. If it does flower it is in the mantle vegetation so is not wind-spread. Only tree pollen appears in the long term records, giving a false impression of closed-canopy forest.
Saproxylic beetles demonstrate that there were large, open grown trees
Back to the Netherlands hypothesis. The herbivores introduced were regulated bottom up by the amount of food. There is no such thing as a carrying capacity - every year is different.
The false baseline is that herbivores must have been in very low densities otherwise there could not be a forest. So bison and red deer numbers are kept at too low a density. A wrong theory can cause an overkill. Bison are an IUCN red list species yet are still shot to maintain low densities.
Sprint shrubs became established at high deer densities
In the Holocene large herbivores are keystone species and drivers of the natural succession.
Vera’s hypothesis explained here:
http://onlinelibrary.wiley.com/doi/10.1111/j.1365-2745.2004.00964.x/abstract
http://www.knepp.co.uk/Other_docs/Frans%20Vera/Birks%20over%20Vera%20in%20TREE1.pdf