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Ecological Sustainability and Urban Green Space |
RINGKØBING
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Urban Density
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RINGKØBING CASE STUDY - HABITAT QUALITY
The findings are discussed in relation to the different land use categories and the density of residential development.
Residential areas Existing housing areas The majority of dwellings in Ringkøbing are one family houses. These developments have grown around the medieval centre from the turn of the century, first along the fjord to the south of the old town centre, then inland to the east of the centre. This pattern of development can be traced by the architectural style of the residences, which has been very well documented in a special Ringkøbing volume of the Municipal Atlases, edited by the Danish Ministry of Environment (Miljøministeriet, 1993). The oldest areas of substantial, one and a half storey red brick houses along the fjord, were built during the first decades of this century. They have well developed gardens with a fair ratio of old trees, the height of which often does not exceed the height of the houses, which create a shelter from the prevailing west wind. This is especially true of the horse chestnut and maple trees. The problem of densification of similar areas seen in other towns and indeed in other countries (Nyhus, 1996), generally does not happen in this area, and so the consequent decrease of especially big trees has not occurred. However, the majority of the big trees are elm, which is unfortunate, as Dutch elm disease is approaching the built up areas from the countryside, just east of town. The disease is most likely to cause a large decrease in the tree cover over the coming years and consequently also a decrease in the total amount of vegetation volume of these areas. The number of trees, the high rate of vegetation cover and the generally high species diversity and structural diversity observed in the field evaluation suggests that these areas are fairly rich, urban habitats. This thus supports the often stated argument that one family housing areas are generally rich habitats (Madslund and Pape, 1991 from Sukopp, 1982). However, our studies show that this is not necessarily the case in younger developments, i.e. from the mid 1960s onwards. There is a general coherence between the age of the developments and the habitat quality of the gardens, as well as of the common spaces: The younger the developments, the lower the habitat quality of the gardens. This seems obvious, but the Ringkøbing study suggests that this difference is not only caused by a simple difference in the age of vegetation, but by a change in the choice of plant material over the years. Except for birch the large deciduous tree species are generally absent in the newer gardens, whilst a wide use of cultivars of flowering bushes and dwarfed evergreens reflects the "modern" supply of self-service garden nurseries. Fruit trees are still found frequently, but typically they are grafted on dwarf stock. They will thus never grow to the size of the large grafted fruit trees of older gardens and so will never amount to the same volume. Especially in the southern part of town, municipal planning visions of creating vegetation-sheltered common spaces in, and wind break plantings along, the residential developments were carried through. The result shows today in both the climatic conditions and the habitat quality of these areas. The newest developments have smaller gardens than in the 1960s-1970s developments. In accordance with the pilot study the amount of paved areas is still the same, and the vegetation area thus smaller. This means that there will be even less chance for larger trees to grow to and remain full size, due mainly to the shade effect. Moreover the common spaces of these developments are no longer planned in the same detail and the planting is not carried out by the municipality, among others, due to tight budgets. Creating a vegetation basis for a future high level of biodiversity of the majority of residential areas, including planning, implementation and management, is left, therefore, to private initiative and owners' associations. Examples in Ringkøbing illustrate that this solution is not always optimal, especially for the common spaces. Different attitudes, the expense and a visible lack of expertise, are typical barriers to a visually and ecologically successful result. The situation is much the same in the low density areas, which except for one large development are dispersed into smaller groups in the single family housing areas. The municipal planting of common areas has diminished over the years, so the newer developments especially generally contain little but lawn. Additionally, the fragmentation of areas typical of low density developments, including the small, private gardens, leaves little space for (stands of) trees, hedgerows and other considerable vegetation volumes. This means that height and volume of vegetation declines with density. This finding is similar to that of the pilot study. In the vegetation cover map of Ringkøbing the low density and single family residential areas typically show 30%-50%, and 50%-70% of vegetation cover respectively (Vegetation cover map -below), but compared with the map of coverage of trees and bushes ( Map of cover of trees and bushes - below) which is generally under 10%, it becomes clear that lawns and low vegetation prevail to a degree, resulting in a low score on habitat quality. The older areas just south of the old town centre, described above, and a couple of areas further south,which were developed according to the planning paradigms for single family housing areas of the 1960 and 1970s, have a higher score, as indicated on the map (Habitat quality for residential areas map - below).
The green spaces of the three apartment block developments in Ringkøbing likewise have little but lawn, although there is plenty of space for planting. In the pilot area of Køge the two apartment block developments studied had a higher volume of vegetation than even the parks (Vegetation volume in Køge structure zones, measured in cm per sq.m. vegetation area), and there was still sufficient lawn for recreational activities. However, the lawns of the Ringkøbing apartment block areas are not unusual. In a study of about 250 developments having or due to have their green spaces renovated, about half had little but lawn and lowshrubberies (Attwell et al.,1998). |
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