Nature Policy, Large Ecosystems
von H. Kampf, Wageningen / Niederlande
4. Provide more room for naturalness
The first track
In our countries, whether the Netherlands, Germany, England or Denmark, "nature" is often the remains of centuries-old forms of human activity. The dunes have been much influenced by coastal defence and overgrazing by cattle, sheep and goats. The marshlands are often left over from peat extraction. Our meadow bird areas and botanical grasslands arose from centuries of pasturing or haymaking, on land reclaimed from wasteland. The heaths, except for perhaps the coastal heathlands, are left over from such practices as timber cutting, peat cutting, burning and grazing.
"Natural nature or wilderness" is quite rare. Developing nature is actually a contradiction is terms. But nature is also stubborn. Natural processes cannot be destroyed, and experience has shown us that if the abiotic conditions, like soil, water, and air quality, are right, then a lot is possible.
But what is this "natural nature" supposed to look like? Plants and animals have names, that is simple, as do vegetation systems and communities. You can talk about them with those who understand the language. But nature and management goals are often formulated in abstract terms and only deal with the long term!
That is why we have developed a system that describes nature or management goals in terms of target processes and target species. We have chosen fine names for "natural nature", and determined the acreage be realised by 2020. This means that we have a clear qualitative, quantitative and measurable division of tasks in terms of processes, species and time.
For large-scale nature this comes down to:
This approach aims to create nature areas with as little human intervention as possible.
4.1 Population development of large herbivores
As an example of track A - nature as natural as possible - I would like to explain the development of large herbivore populations.
The results in nature areas in the Netherlands with cattle and horses living in a kind of wilderness seem very positive so far. Here is an example from the area known as the Oostvaardersplassen: the surface area for the grazers has increased (as you see from the white line in Fig. 5), and the population is also growing very fast, maybe too fast since there are no natural predators.
In 1983 about 35 Heck cattle were introduced, and more were introduced in 1987 and 1989. The first years were rather difficult as you can see from the red line in Fig. 5. Accidents have a greater impact on small populations than on large ones. Since 1986 the Heck cattle population has been constantly growing, doubling itself about every 4 years. Since a few years some stabilisation seems to appear.
The development of the Konik horse population also got off to a slow start. It took about 7 years before the population began to grow rapidly. However, there are indications that the growth rate of the population will decrease as the area becomes overpopulated. This is an interesting point for further ethological research.
The purple line shows the development of the red deer population. Those animals, a mixed population from Scotland, Holland and the Czech Republic, do not seem to have had problems with their new home. From the beginning this population grew very rapidly and recently passed the number of horses. For red deer a large, still undiscovered marshy area is available yet.
For the roe deer, the introduction of red deer was not so advantageous, as the green line shows. Causes are: changing of the vegetation (more elder - Sambucus nigra) and since 1998 a higher water level.
Horses and cattle do not need a strong fence. However, choosing red deer means that either the animals roam freely in a large area or must be fenced in, so when the red deer were introduced, a strong fence was needed. For roe deer, which were used to wandering into and out of agricultural land, it was an unwelcome restriction. Roe deer has more interest in the mixed forest areas outside the Oostvaardersplassen.
Another complication was the building of the railway line along the border of the Oostvaardersplassen. The line forms a barrier between the other ecological areas. Solutions for making this barrier more transparent (using existing tunnels) are in discussion now.
These slides (Fig. 6) show the population development of both the Heck cattle and Konik horses. Striking are the parallel lines of males and females. There are slightly fewer bulls than cows, but there could be higher mortality due to fighting between them. One incident involved two bulls fighting and a third that rammed one of them in the ribs. The green line indicates the number of births. There may be a slight decline nowadays. Last year 25 animals were killed for veterinary research. The only serious disease found was IBR (Infectious Bovine Rhinotracheitis).
For the Konik horses, stallions outnumber the mares. In both figures (6 + 7) the mortality rate is low. However, we must remember that as the average age increases, the mortality rate will do likewise.
4.2 Nature values
The animals in the Oostvaardersplassen can live a life fast as natural as possible, like this relieving konik: excrements of a number of stallions as a tool to set hierarchy.
Red deer can develop themselves to strong stags and will die when time is ripe, as this 19 years old one. The Oostvaardersplassen is a special place for birds such as swans, geese, ducks, waders, herons and birds of prey. The large herbivores are helping each other as well as the other animals. The low grassland area is very suitable for these birds. Cattle, horses and deer have different grazing patterns. Depending on the time of year they eat grass, stinging nettles, thistles, roots, barks of trees and reed. Depending on the number of animals and population dynamics, whether natural or artificial, a park-like landscape may result. Here in a river area, De Gelderse Poort, Galloway grazing results in a half open steppe-like grassland with scrub.
There are already some results. The greylag geese have returned and have been breeding so well over the last century that farmers are starting to complain. The goose has complex environmental demands; essentially, it must have a moulting area and once moulting time is over, sufficient grasslands. While they moult, they are used to living in reed beds, where they can eat the sugar-laden reed sprouts, or on Senecio palustris.
This prevents the water from becoming overgrown with reeds, while the habitat will stay suitable for the water birds and fish. Fishes like stickleback are an important food for heron species, like spoonbill and white egrets, which are increasing. In the spring of 2000, 10 - 12 breeding couples of the great white egret and 6 of the little white egret were counted.
The Oostvaardersplassen is a nutrient-rich, moist area. Because of its isolation, the area is still relatively poor in plant species, since the Southern Flevopolder - in which this area lies - was only drained in 1968. More than 30 years of development has offered many opportunities for birds, butterflies, etc. while the natural introduction of plants is slow. Introduction of plants has to be considered. Pioneer plants such as reeds, thistles, stinging nettle, clover, elder and willows arrive first. A species such as the red eyebright (Euphrasia) probably arrived with seeds in grass used a winter fodder for the cattle and horses. This hay was from Lauwersmeer, where this species is common. In this area we chose to leave a lot to nature and not introduce many species.
We also do not let in any water, and only drain off water when it exceeds a certain level. In this whole area of almost 6,000 ha there are only two dams, which are set at a fixed level. This means of course that we get wet years and dry years, and that some birds will disappear (albeit temporarily) if their habitat becomes less than suitable. This happened with the spoonbill a few years ago. It went in the Oostvaardersplassen from 130 breeding pairs to zero - a dynamic system indeed. The result however was that these birds suddenly appeared in many other places, as far away as Denmark. Our goal of 1200 breeding pairs was thus attained earlier than expected.
The Oostvaardersplassen seem to function as a sort of overflow area for other potential breeding areas, at least for birds. In other areas, like the Veluwezoom, a dry sandy area pushed up during the Ice Age, or the Lauwersmeergebied - recent reclaimed area - , things develop differently. Precisely we know still too little about the influence of grazing on the ecosystem, and until now unfortunately not much accessible has been written about it (grazed heathland).
It is clear that grazing is more natural than such large vehicles in nature areas. Comparable with here, where the highland cow with its calve is monitoring the results.