The relationships between properties of present landscapes and species diversity within fragmented grasslands have been the subject of many studies. However the potential roles of grassland history ...
In the past, arable fields were established locally on the alvar on Oland. Several persisted until the present time, but some of them were abandoned shorter or longer ago. We found a series of arable fields forming a chronosequence: still cultivated, ca. 20 years abandoned, ca. 50 years abandoned, and never cultivated. Species of man-influenced habitats gradually disappeared from the former arable fields, but a few persisted after 50 years. A group of alvar species had re-established after 20 years, but others did not re-establish even after 50 years of abandonment, although they are present in the local species pool. We found no evidence of dispersal as a constraint for re-establishment.
We studied dry grassland vegetation on southern Oland, both within and outside the Great Alvar, using the Braun-Blanquet approach. We were able to distinguish 15 associations or equivalent units belonging to three major syntaxa. Dry grasslands on sandy soils (class Koelerio-Corynephoretea; subclass Koelerio-Corynephorenea) occurred along the east and west coasts. Weathered rock and outcrop communities (class Koelerio-Corynephoretea; subclass Sedo-Scleranthenea) inhabited shallow skeletal soils, mainly on the Great Alvar. Semi-dry basiphilous grasslands of the class Festuco-Brometea occurred on moraine soils, which were the least extreme in terms of soil moisture and nutrient availability. Whereas the first category comprises impoverished variants of widely distributed syntaxa, all Sedo-Scleranthenea and Festuco-Brometea communities lack direct counterparts in central Europe. The alvar communities proved to be floristically well separated from the others. Species density on 4 m2 was highest in the Sedo-Scleranthenea (that of the Gypsophilo fastigiatae-Globularietum vulgaris with 80 taxa being one of the highest known), intermediate in the Festuco-Brometea, and lowest in the Koelerio-Corynephorenea. Harsh and variable conditions, small plant sizes, and a large local species pool are considered possible causes.
In consequence of variations in geology and soils, in climate, and in its wide extent in longitude, latitude and altitude, the Scandinavian mountain chain exhibits major variations in natural conditions. Nature is constantly influenced by processes that include both natural forces and human activity.In the early 1990s, there was an intense media debate about current damage to the montane vegetation, which many believed they could observe.In 1992, the World Wide Foundation for Nature, WWF, invited representatives of responsible authorities, reindeer-husbandry interests, voluntary conservation bodies and interested researchers to a conference, which, somewhat erroneously, came to be called the 'Reindeer grazing conference', but which included a spectrum of factors that can affect the montane vegetation.One result of this conference was that, in 1993, WWF initiated a research project, extending over several years, intended to provide information about temporal changes in montane vegetation.Experimental areas distributed along the Swedish mountain chain were selected: the southernmost are on Fulufjallet in Dalama, and the northernmost are ea. 15 km S of Tavvavuoma in Swedish Lapland. (Some placenames are given in modern North-Saamish spelling in Appendix 2) The vegetation types studied were Grass heath, Meadow with low herbs, Dry heath, Birch forest-heath type with lichens and Birch forest-heath with mosses. These cover all major montane areas and are important grazing areas for reindeer.At all study sites, six adjacent plots were selected, half of which were fenced to deny access to larger herbivores, and half were left open for grazing by all herbivores. The composition of plant communities in the field, bottom and tree layer in plots was estimated in 1995-96, and re-estimated three to four years later.Generally, marginal or no effects of enclosure were seen on the vegetation communities, and there were no differences between vegetation types.Up to the end of the 19th century, travellers in the montane region, both Saami and outsiders, ocularly assessed the plant cover. As a rule, they reported a good supply of reindeer fodder plants, especially lichen species.From the end of the 19th century, there began to be observations of severely denuded lichen cover, especially in areas exposed to a veritable invasion of Saami and reindeer from the north-Norwegian and north-Finnish reindeer grazing areas. Incomers from those areas introduced an extensive form of reindeer husbandry, developed to suit conditions on the Finnmarksvidda and in northernmost Finland, where large reindeer herds could readily find grazing on well-demarcated headlands and islands during the snowfree season, without much supervision.The conflicts of interest between the incomers, and indigenous Saami who wished to carry on an intensive form of reindeer husbandry, with closely supervised herds, were great. From the beginning of the 20th century, state interventions, in the form of commissions of enquiry and field surveys, were instituted. Their aim was to resolve existing conflicts, to ensure a sustainable access to grazing, and satisfactory profitability. The results cannot be said to have been satisfactory.
Nutrient and water supply, light availability and removal of biomass were manipulated in a limestone grassland community on the Swedish island of Oland from 1990 to 1993 in order to investigate how these factors influence species richness and year-to-year turnover at fine scales. Turnover, broken down into disappearance (‘extinction’) and appearance (‘immigration’) of vascular plant species, was measured at different spatial scales in plots ranging from 4 cm2 to 0.25 m2. For most treatments, turnover was highest at the finest scale, both measured as absolute and relative numbers. Turnover rate increased at all scales when the treatment implied such a change in the environment, where application of fertilizer was combined with shading. In these cases, disappearance of species largely exceeded appearance in a predictable manner, and resulted in species-poor assemblages at all scales. In plots treated with either fertilizer or shade, there were large differences in the direction of the turnover (i.e. whether immigration or extinction dominated) between years, apparently depending on the weather conditions in the respective year. After drought spells total turnover was also high for such treatments, whereas plots regularly receiving additional water supplies had rather similar turnover rates during the whole experiment.
The dry alvar grasslands of Oland: ecological amplitudes of plant species in relation to vegetation composistion.
Den nordiska utbredningen av Lactuca alpina, Aconitum septentrionale, Ranunculus platanifolius och Polygonatum verticillatum
Die Verbreitung der Alchemilla-Arten aus der Vulgaris-Gruppe in Nordeuropa (Fennoskandien und Danemark)
Scorpidium turgescens (Th. Jens. ) Moenkem. En senglacial relikt i nordisk alvarvegetation.
