Scale-dependence of vegetation-environment relationships in semi-natural grasslands

• Published in: Journal of vegetation science 2008-02, Vol.19 (1), p.139-148
• Main Authors: Auestad, Inger, Rydgren, Knut, Økland, Rune H.
• Format: Article
• Language: English
• Subjects: Betula pubescens; botanical composition; Botany; Complex gradient; Environmental aspects; environmental factors; Grasses; Grassland management; Grassland soils; grasslands; Grazing; Growth; Hieracium; Management; Nested design; Nested design Scale; Ordination; pasture management; Pastures; Physiological aspects; plant communities; Plants; range management; roadside plants; s; Scale; Seminatural ecosystems; Soil water; soil water content; Species; Split-plot GLM; Vegetation; Vegetation dynamics
• ISSN: 1100-9233; 1654-1103; 1104-7402
• DOI: 10.3170/2007-8-18344

Questions: Which environmental and management factors determine plant species composition in semi-natural grasslands within a local study area? Are vegetation and explanatory factors scale-dependent? Location: Semi-natural grasslands in Lærdal, Sogn og Fjordane County, western Norway. Methods: We recorded plant species composition and explanatory variables in six grassland sites using a hierarchically nested sampling design with three levels: plots randomly placed within blocks selected within sites. We evaluated vegetation-environment relationships at all three levels by means of DCA ordination and split-plot GLM analyses. Results: The most important complex gradient determining variation in grassland species composition showed a broad-scale relationship with management. Soil moisture conditions were related to vegetation variation on block scale, whereas element concentrations in the soil were significantly related to variation in species composition on all spatial scales. Our results show that vegetation-environment relationships are dependent on the scale of observation. We suggest that scale-related (and therefore methodological) issues may explain the wide range of vegetation-environment relationships reported in the literature, for semi-natural grassland in particular but also for other ecosystems. Conclusions: Interpretation of the variation in species composition of semi-natural grasslands requires consideration of the spatial scales on which important environmental variables vary. Nomenclature: Lid & Lid (1994) except for Betula pubescens agg. (which includes B. pubescens and B. verrucosa) and Hieracium spp. (which includes all Hieracium species except H.umbellatum).