Past, present and future land cover changes and their effect on plant species diversity patterns
Sara Cousins (project leader)
Summary of results with list of publications from Department of Botany, Stockholm University.
Email: cousins@botan.su.se
This is how it was before – haymaking in the 1920s
Biodiversity is highest in semi-natural grassland in the cultivated A semi-natural grassland is grassland that has never been ploughed or treated with synthetic fertiliser. One reason for the high species richness is that grasslands have been grazed and cut over many centuries. Today, only small remnants of semi-natural grassland remain.
Loss and fragmentation of habitats are a threat to biodiversity. Results from earlier studies are often contradictory since some of the historical landscape is of great importance for today's vegetation, while others demonstrate the opposite, i.e. the vegetation reflects the habitat size of the present. Few have analysed the usual modern landscapes in which little semi-natural grassland remains.
The overarching objective of this project was to combine geography and plant ecology in order to explain contemporary species richness, patterns and threats. The focus was on semi-natural grassland, small remnant biotopes (midfield islets and road verges), abandoned grassland and new grassland on old arable land. A combination of methodology and theory from these two disciplines has increased understanding of today's species richness, which is of great importance for the care and restoration of the cultivated landscape in the future. By incorporating different remnant biotopes in larger grazing complexes, species richness can be increased in landscapes which otherwise have little semi-natural grassland left.
Quantitative genetic effects of habitat fragmentation in two grassland species
Stefan Andersson (project leader)
Summary of results from Lund University.
Email: stefan.andersson@ekol.lu.se
Grazed or mowed grassland (semi-natural grassland) contains a large proportion of the biodiversity that is found in the Swedish cultivated This habitat is appreciated by both landowners and tourists and those of the general public who are interested in nature, and it has a high nature conservation value. Many grassland species have been adversely affected by the fragmentation that has occurred in conjunction with the comprehensive rationalisation of agriculture over the past 50 years.
Species which previously had contiguous distribution are divided up into small isolated populations where random processes such as genetic drift occur. The genetic variation disappears from the gene pools and the populations become more inbred. This process can be studied most easily by comparing genetic variation in small and large populations. Many researchers have based their studies on "marker genes", but few have studied genetic impoverishment in polygenic characteristics, i.e. characteristics that are affected by many genes.
This project studied two common grassland species (meadow saxifrage, Saxifraga granulata and quaking grass, Briza media). The results show that the selectable polygenic variation still appears to be characterised by the population structure that earlier prevailed in the more contiguous historical The reason that no effect of fragment size was revealed may be that populations are still too large for genetic drift to be of any major importance. Another possibility is that there have not been a sufficient number of generations since fragmentation began, or that gene flow in the form of seeds or pollen counteracted genetic impoverishment by introducing new variation into the gene pools.
Agricultural intensification and the decline of farmland birds. The importance of landscape heterogeneity
Tomas Pärt (project leader)
Summary of results with list of publications from SLU.
Email: tomas.part@nvb.slu.se
Conditions are bad for birds in the farming In England, where this is noted most, people are even talking of a second "silent spring". Today there is general agreement that the main reason is intensification and effectivisation of agriculture. Is there no sanctuary for birds? The situation is perhaps better in Sweden which despite all changes has a more varied farming landscape.
The study clearly shows that the effects of nature conservation measures to reverse the negative population trends of species vary between species and agricultural landscapes, and this is the reason that no single nature conservancy strategy that is generally successful for all types of landscape has been found. A judicious strategy may therefore be to concentrate on creating farming landscapes of more varied character. This implies that support should be given to different measures that are geared to the agricultural region and landscape in question. In simple terms, support should be given for low intensity agriculture on the large plains and for cereal production in the small scale farming landscapes in the forest dominated regions.
Genetic variation, heterozygocity, inbreeding and gene flow in relation to population size and environmental variation
Lars Gustafsson (project leader)
Summary of results with list of publications from Animal Ecology, Uppsala University.
Email: lars.gustafsson@ebc.uu.se
Old hay meadows are a characteristic biotope on Gotland which, according to tradition, have been cultivated for more than a thousand years. Today they remain in different stages of management, and in the south of Gotland meadows and deciduous forests form a reasonably contiguous biotope.
The collared flycatcher is a characteristic bird on Gotland which mainly breeds in deciduous forests and meadows. In a long term study, a large population of birds has been observed since 1980. In small isolated populations, the difference in numbers between two consecutive years has been as much as 400%. These dramatic changes can be associated with climatic variations, but extensive thinning may also have great significance for genetic variation. In the project, a study was made of the way in which genetic and phenotypic variation can be retained or modified in bird populations.
Population dynamics and persistence of birds in heterogeneous farming landscapes
Henrik Smith (project leader)
Summary of results with list of publications from Department of Ecology, Lund University.
Email: Henrik.Smith@zooekol.lu.se
Agricultural change has resulted in decreased abundance and distribution of many organisms. Farming methods of increasing intensity have produced larger harvests, but may at the same time have resulted in a decrease in biodiversity. One general cause may be that the more intensive farming methods have resulted in a loss of ecological heterogeneity. The project has investigated the consequences of ecological heterogeneity at different spatial scales on species numbers, population sizes and reproductive success in birds.
The studies have shown that the diversity of birds, but not their density, was affected by the interaction between the way intensive farming is carried out and the complexity of the The reason for this was that there was no statistically verified effect of organic farming on bird diversity in mosaic landscapes, but there was a positive effect in simplified agricultural plains. Studies showed that insects exhibit similar patterns.
The reason for the decline in starling numbers in colonies spread over Sweden was investigated by observing population size and reproductive success over two decades. Through analysis of aerial photographs, population change was compared with the changes in the The rate at which the number of starlings declined was related to how much semi-natural grassland disappeared in the area near the colony.
It was found that starlings mainly forage for the nestlings in grassland. However, some populations decreased without any sign of a local cause. The reduction may instead be due to changes in overwintering areas. Waders also exhibited a similar relationship between changes in the landscape and declines in population sizes.
The results show that both farming intensity and the spatial variation of the landscape can affect the abundance of birds and insects. Organic farming can restore the diversity at small scales, while studies of landscape heterogeneity show that variation at larger scale also has significance. In order to restore the biodiversity of the agricultural landscape, heterogeneity should therefore be recreated at multiple spatial scales.
Responsible for this page: Kerstin Franklin