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Nature Reserve Oostvaardersplassen, |
A brief description of the main characteristics of the each of the eight landscapes that comprise the structure of the Oostvaardersplassen, some details of the vegetation structure and the fauna found in each of the landscape types is mentioned along with the seasonal changes throughout the year.
Type 1: Large-scale shallow open water This landscape is permanently covered with water. The area is especially significant for fish and fish-eating birds. It also functions as an important resting area for waterfowl, spoonbills, herons, geese and ducks.
Type 2: Very shallow open water with locally emerging mudflats and vegetations This landscape is characterised by the strong fluctuations of the water level within and between years. This leads to a landscape, alternating between mudflats, pioneer vegetation and open reed lands. Zones with clear and turbid water can occur next to each other. It is suitable as spawning area for fish. For a lot of birds it functions as feeding, moulting and breeding area. The open reed lands are especially important as feeding area for moulting greylag geese as well as for ducks. The grazing by greylag geese has a great impact on the structure of the vegetation. Large numbers of waders and herons forage on the mudflats at the end of summer and during autumn.
Type 3: Not permanent inundated marsh vegetation (reed land, roughs, willows) This landscape is comprised of reed land, and willow growths. The water level dynamics are principally the result of fluctuations in precipitation and evaporation. The effect of flooding is very small, even with the effects of the grazing. The wet reed land exists mostly as a dense reed land without willow growths. The dry reed land contains degenerated reed in which herbs develop. Many bird species, including harriers, water rails, spoonbills, bitterns and singing birds use this landscape as a breeding place. Willow woodland in this area is especially significant for colonial breeding birds like cormorants. Mammals like mice species and marten species are common. Characteristic insect species such as loop beetles and butterflies are present.
Type 4: Large-scale wet grassland The water level fluctuates during the year so that during the winter months (from October to May) the water covers the grassland slightly. During spring and summer the water level drops to approximately 0.5 m below the ground level. The large grazers have a major influence on the vegetation. During winter, the water level is too high to allow the grazers to pass through or graze the fields. However, when the water level has dropped, the grazing is intensive. This area is a significant feeding area for the greylag geese, especially during moulting time and for ducks and waders as complementary feeding areas. It also serves as a foraging and breeding area for spoonbills, herons, water rails and harriers. There is a huge variation in numbers and species present here. Water vole, hare, stoat, weasel, polecat, fox and roe deer are living here as well. Locally the area is also suitable for reptiles, amphibians, butterflies and dragonflies and other species.
Type 5: Large-scale dry grassland During the winter period, the ground water level stays below ground level of these grasslands. In summer it drops well below ground level. The area is grazed throughout the year by the large grazers and during the winter season it is partly and temporary in use by geese as a feeding area. The landscape is an ideal area for weasel, stoat, hare and red fox, roe deer, and mice.
Type 6: Relatively large scale dry grassland, rough growth, brushwood and clusters of trees The groundwater level stays in the winter period under ground level of the grassland. During summer the level drops well below ground level. Grazing is more intensive in this area during winter than it is in summer. The number of species and the density of birds in this landscape are relatively low. Characteristic species include the red-backed shrike, whinchat, blue throat, quail, corn-crake and great grey shrike. The mammals, insects and amphibians from the ‘Large-scale dry grassland’ are also present in this landscape, though in smaller numbers.
Type 7: Relatively small-scale dry grassland, roughs, brushwood and clusters of trees The groundwater level remains under ground level of the grasslands throughout the year. The grazing in this region is extensive during the winter period and in comparison with other foraging areas it is more incidental. The vegetation structure of woods and rough growth is important for songbirds, and birds of prey such as the bussard, hawk, hobby, sparrow hawk and long-eared owl which use the area as a hunting ground and breeding area. Besides from mice, the area is suitable for mice, martens, rabbits, roe deer, red deer and red fox. It also has a diverse insect composition.
Type 8: Small-scaled woodland This landscape type can be found both in the border zone and in the wet marsh zone (see ‘Marsh vegetation not inundated’). Willow wood growths occurs spontaneously in the first stages of development. This vegetation is important for mammals as shelter. It comprises a rich birdlife and a high abundance of insects.