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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

How former arable fields with permanent grazing differ from managed semi-natural pastures in Sweden

Galin, Isolde January 2019 (has links)
New farming needs and innovations have, over time, led to changes in land use. Arable fields have been turned into pastures and semi-natural pastures into arable fields. Due to the ecological value of continually grazed semi-natural pastures in Sweden the aim of this study is to find out how former arable fields that are permanently grazed differ from semi-natural pastures. In this study I selected appropriate semi-natural pastures from a national monitoring program on seminatural- pastures and meadows. Plots continuously grazed were compared with grazed plots on former arable fields. Pair-wise differences in the Ellenberg indicator values Light (L), Soil moisture (F), soil pH (R) and soil nitrogen (N), vertical coverage of trees, bushes and vegetation, species richness and species composition were tested. Except for species composition there were only small differences between former arable fields that are permanently grazed and semi-natural pastures. That means former arable fields can with time and grazing gain many of the values continuously grazed semi-natural pastures have.
2

Past and present management influences the seed bank and seed rain in a rural landscape mosaic

Auffret, Alistair G., Cousins, Sara A. O. January 2011 (has links)
1. Seed bank and seed rain represent dispersal in time and space. They can be important sources of diversity in the rural landscape, where fragmented habitats are linked by their histories. 2. Seed bank, seed rain and above-ground vegetation were sampled in four habitat types (abandoned semi-natural grassland (ABA), grazed former arable field (FAF), mid-field islet (MFI) and grazed semi-natural grassland (SNG)) in a rural landscape in southern Sweden, to examine whether community patterns can be distinguished at large spatial scales and whether seed bank and seed rain are best explained by current, past or intended future vegetation communities. 3. We counted 54 357 seedlings of 188 species from 1190 seed bank and 797 seed rain samples. Seed bank, seed rain and above-ground vegetation communities differed according to habitat. Several species characteristic of managed grassland vegetation were present in the seed bank, seed rain and vegetation of the other habitats. 4. The seed banks of SNGs and the seed rain of the FAFs were generally better predicted by the surrounding above-ground vegetation than were the other habitat types. The seed rain of the grazed communities was most similar to the vegetation in the FAFs, while the seed banks of the abandoned grasslands most resembled the vegetation in SNGs. 5. Gap availability and seed input could be limiting the colonisation of target species in FAFs, while remnant populations in the seed bank and the presence of grassland specialists in the above-ground vegetation indicate that abandoned grasslands and mid-field islets could be valuable sources of future diversity in the landscape after restoration. 6. Synthesis and applications. SNG communities are able to form seed banks which survive land-use change, but their seed rain does not reflect their above-ground communities. It is important that grassland plants set seed. By connecting existing grasslands with restoration targets, increased disturbance in the target habitats would allow for colonisation via the seed bank or seed rain, while decreased grazing intensity would benefit seed production in the source grasslands. Otherwise, landscape-wide propagule availability might increase with a more varied timing and intensity of management.

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