Xeric sand calcareous grasslands or sand steppe is a rare habitat type in Sweden. In our country the occurrence of sand steppe is limited to eastern Scania and a few sites on the Baltic island of Öland. The availability of calcareous sand and a continuous management of the soil surface regulate formation of the sand steppe. A low annual precipitation is also a critical factor. Due to these unique circumstances the habitat type has never had a great distribution in the country. Sand steppe is closely related to the agricultural landscape with a long tradition of extensive arable farming and grazing animals. Patches of bare sand mixed with a sparse cover of low grass vegetation is the characteristic of the habitat. Changes in land use linked to agricultural modernization, and pine-tree plantations in former sand steppe areas, have made the habitat seriously threatened today. The purpose of the survey has been to carry out a detailed mapping of sand steppe on Öland and to study how the habitat changed over the last fourteen years. I wanted to see what such a change analysis could say about the future of the sand steppe on Öland where the assumption was that the habitat is reduced and the overgrowth is inevitable without restoration measures. As with other similar types of culture-guided grasslands the sand steppe habitat is never in a stable equilibrium. Without disturbance of the topsoil layer, grazing animals or human activity the sand steppe will get overgrown. By using the land for cultivation the process of succession is delayed. This process can be illustrated by the three development phases associated with sand steppe, the initial phase (1st class), the optimal phase (2nd class), and the phase of degradation (3rd class). Both the lack of management practices and improper land use is a threat to the habitat. A number of rare and red-listed plant species are associated with the habitat together with the indicator species, Koeleria glauca. Sand steppe is also a very important habitat for insects, order Hymenoptera and order Coleoptera. The current situation of sand steppe on Öland consists of 15 sites all of which can be found on the east side of the island, along the ancient shorelines from the early stages in the development of the Baltic Sea. The sites have been carefully mapped by counting the number of individuals of Koeleria glauca and by the quantification of the three phases of development for each site. The number of Koeleria glauca individuals on Öland (July 2009), is 604 805. A change analysis was carried out to compare the distribution of sand steppe on Öland in 1995 with the distribution in 2009. Because of incomplete data in the 1995 inventory, the result of the analysis is considered to be a trend. The total area of sand steppe on Öland has increased, from 36.5 to 41.5 hectares since the 1995 inventory. This is contrary to the hypothesis that the area of sand steppe had declined. The reason to this total increase is probably due to greater awareness of the habitat sites. The distribution of development phases shows a clear dominance of the 3rd class-surfaces. The reason for such a large increase of the third phase is mainly due to an increased knowledge of the existence of Koeleria glauca at each site. But since the proportion of the initial phase and the optimal phase have been reduced this suggests that the 3.rd class-surfaces has increased at the expense of the 1.st- and 2.nd classes. This provides a future indication for the sand steppe sites on Öland where overgrowth is inevitable, without restorative management measures to create new sand steppe. The assumption that small sites get overgrown faster than large sites has been clearly confirmed. Such a fragmentation process, which also is a result of the overgrowth, is an additional threat in the longer term. At an increased habitat fragmentation risks of isolation and inbreeding might occur and finally a gradual and increasing extinction debt. Since the sand steppe environment also allows for species that have general needs of bare sand the restoration and preservation of the habitat type is of great importance. Thanks to the distinctive character of the habitat there is a large commitment among nature conservation authorities and in the final stages of this work a decision was made regarding Åby sandbackar, a prospective nature reserve on Öland.
| Identifer | oai:union.ndltd.org:UPSALLA1/oai:DiVA.org:su-191202 |
| Date | January 2009 |
| Creators | Lundquist, Jonas |
| Publisher | Stockholms universitet, Institutionen för naturgeografi |
| Source Sets | DiVA Archive at Upsalla University |
| Language | Swedish |
| Detected Language | English |
| Type | Student thesis, info:eu-repo/semantics/bachelorThesis, text |
| Format | application/pdf |
| Rights | info:eu-repo/semantics/openAccess |
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