Open, sunny, warm areas of sandy soil with a great profusion of flowers are attractive not only to flora and fauna, but also to human visitors. Under the heading Habitat Types and Species is a description of the enormous diversity of birds, insects, flowering plants and fungi that can be found in our sandy habitats. What many of these species share is that they benefit from the warm, dry climate provided by sand dunes and heaths.
The abundant flora and fauna of these environments are threatened by a large number of different factors. In line with the increasing threat, the deficiencies that lead to an environment with ever decreasing range of species also increase. Sand Life will take action to combat many of these threats and deficiencies so that life will once again have the opportunity to thrive in the sand dunes and heaths of southern Sweden!
Some Threats to Biodiversity in the Sand Dunes and Heaths
Planting and Cultivation
One of the gravest threats to the flora and fauna of the sand dunes and heaths is the planting of trees and shrubs that has taken place at various times. Pine and Japanese rose were planted on many sand dunes and heaths during the 17th and 18th centuries in order to prevent the sand from drifting. Drifting sand happened because the trees that had been growing there were felled and also because the turf had been broken up. The growing population needed increasing quantities of timber for fuel and house-building. Sweden was also involved in several wars which, aside from timber, also required enormous quantities of turf for the construction of large fortifications. The larger number of people required more food and so the sandy soil was cultivated all the more frequently and was not given the chance to rest. The poorest soil was used to graze animals and the vegetation was never given a reasonable chance to recover. Grass and herbaceous plants couldn’t bind the sand together and prevent it drifting as they had done previously and there were no longer any trees or bushes to stop the sand.
The cultivation of the poor sandy soil has now decreased significantly, and there has been no risk of drifting sand for a couple of hundred years. In addition, we have now built over a much larger area, compared to then, which further reduces the risk of the sand once more beginning to move. There is no longer any need for protective woodland and for shrubs to bind the sand together. Instead, we have the opposite problem – not enough exposed sand.
Pine (Pinus spp.) and Japanese rose (Rosa rugosa) now cover large areas because they have been allowed to grow freely and have spread out across the open sandy dunes and heaths. Because the sandy soil provided a low yield, it has been more profitable to use these areas to plant trees and to build roads and buildings. The sandy areas are all naturally beautiful and many are close to the sea, it is thus not unusual that they have been considered natural places to build summer cottages. In recent years, the splendid qualities of sandy soil for cultivation have been noticed. It is possible to plan the large quantities of nutrients and pesticides that are needed for a high yield and the cultivation of vegetables has thus become very profitable on this permeable soil.
Planting and commercial exploitation have resulted in the disappearance of exposed sand from the landscape. When there was no longer a demand for turf and it was no longer attractive to allow animals to graze the sandy pasture, these areas became increasingly overgrown. The environment became damper and cooler. In addition to the overgrowth of plants such as pine (Pinus spp.) and Japanese rose (Rosa rugosa) that took place, the open sand dunes and heaths have also become much more densely vegetated. The surface of the soil is shaded and there is a detrimental impact on the plants and fungi that need a dry, light environment.
There is lime in the sandy soils of Skåne and Öland. This lime binds to a number of nutrients which prevents plants from being able to make use of them. The plants of sand dunes and heaths have, in turn, adapted to this nutrient-poor environment.
When it rains, the lime is carried away in the rainwater down through the soil and the quantity of lime is reduced naturally. The process is called leaching. At the same time the soil is constantly becoming more acidic (both naturally and as a result of pollution), speeding up the leaching of lime. When the amount of lime in the soil decreases the nutrients that are bound to it are released and plants can then use this excess of nutrition. What then happens is that other plants, who can’t cope with the nutrient-poor environment, grow and compete with the diverse flora of the sand dunes and heaths.
This is a threat to, for example, the sandy grassland in south-eastern Sweden. The plants that create this habitat can tolerate a high lime content and are thus able to out-compete other vegetation. The same process has also led to the development of the unique range of gasteroid fungi on lime-rich sandy soils.
Another threat to the biodiverse sandy landscape is nitrogen deposition. South-western Sweden, including Skåne and Halland, is subject to the highest level of nitrogen deposition in Sweden; this additional nitrogen works as fertiliser in many of the sand dunes and heaths. All plants require nitrogen in order to grow, but the plants of the sand dunes and heaths are adapted to a nitrogen-poor environment. The result is that the vegetation of sand dunes and heaths are out-competed, as with the situation in leaching of lime (see the heading Acidification above).
Pastures are, for us, a genuine feature of the Swedish landscape and provide beautiful open spaces. Grazing significantly inhibits the overgrowth of shrubs and brush. Grazing also prevents plants that benefit from the additional nutrients from out-competing the natural vegetation of sand dunes and heaths. For many fungi and insects who live on dung, grazing animals are of vital importance.
However, nature is complex and when the proportion of grazing animals increase in the landscape, the number of flowering plants decreases. The fact is that grazing animals on the land encourages the growth of grass. The grass-cover of pasture often develops a dense, sealed surface where the seeds of flowering plants are unable to germinate and grow. The dense surface also prevents the appearance of open exposed patches of sand. The combination of a lack of flowering plants and exposed sand leads, in turn, to a lack of insects. The number of insects has an impact on the number of the animals that eat insects.
Despite the positive aspects of grazing for both natural and cultivated environments, overgrazing can lead to an environment with lower biodiversity if care it not taken.