Epsilon Archive for Student Projects

Abstract

In the lowlands of Europe, grazed wood-pasture landscapes are highly valuable habitat types, with high amounts of biodiversity and other ecosystem services. This study tries to parameterise the dynamics between thorny scrub and tree crown, and the differences in the species composition of pastures and adjacent forests. Field observations were taken at seven protected grazed pastures in southern Sweden. Shrub patches were measured in terms of area, height and species composition, while tree regeneration was measured by height, stem diameter, and crown diameter. The frequency of shrub shoots was measured underneath free-standing mature trees. In adjacent forests, tree regeneration and basal area was measured in thirty meter transects. The results were analysed with a generalised additive mixed model (GAMM) and non-metric multidimensional scaling (NMDS).
There was a significant difference between the relative species abundance and the relative basal area per species between pastures and adjacent forests, with a greater number of light-demanding species regenerating in the pastures. The dynamics between the size of the tree crown and the occurrence of shrubs beneath it follows an S-curve, whilst the shrub shoot density decreases with the size of the tree crown. These results show that grazed wood-pastures can give regeneration pathways to tree species that would have a difficult time growing underneath closed canopies. Due to the value of wood-pastures as a habitat, it is of vital importance that these highly complex ecosystems are fully understood and modelled, so that they can be protected better in future. These parameterisations could be used in the future to create a robust model of these ecosystems.