Management Effects on Low-Herb Diversity in Outlying Grasslands
During the past century there have been vast changes in land use, which have led to succession processes in outlying lands. As a consequence, species-rich semi-natural grasslands are disappearing and many of their associated species have become threatened with extinction. For targeted and successful conservation of these species, it is important to identify the ecological factors determining their distribution and abundance. The aim of this study was to reveal effects of different management types on the distribution and abundance of rare low-herb species, while controlling for vegetation type, moisture and pH. A case study was performed at Brekken, an upland outlying landscape in Norway. Seven study species were chosen; three Botrychium species (B. lunaria, B. boreale, B. lanceolatum), three gentian species (Gentiana nivalis, Gentianella campestris, Gentianella amarella) and one orchid (Nigritella nigra). Species observations were obtained by distance transect sampling. Within transects, present vegetation was recorded as intervals of distinct types, and moisture and pH was measured and used in characterization of vegetation types. Using generalized linear models and generalized linear mixed models, density and probability of occurrence was modeled in response to management (mowing, grazing and abandonment) and vegetation types. For all species in total, both the density and the probability of occurrence is higher in grazed areas than in mown and abandoned areas, and their habitat ranges are wider in the grazed area. From models fit per species, the gentian species show higher density or probability of occurrence in mown areas. Most of the studied species were shown to be at highest density and/or have highest probability of occurrence in low-grown grassland vegetation. Such grasslands are products of land use, and therefore management effects are in some species analyses assumed to be masked within significant effects of vegetation types. In restoration and conservation, type of management should be determined specifically for each site, based on local land use history and the overall conservation aim.
Place, publisher, year, edition, pages
Institutt for biologi , 2013. , 53 p.
IdentifiersURN: urn:nbn:no:ntnu:diva-21410Local ID: ntnudaim:10218OAI: oai:DiVA.org:ntnu-21410DiVA: diva2:637021
Moen, Asbjørn, ProfessorOien, Dag-IngeSpeed, James David Mervyn