Table 1.
Altitude, annual precipitation, summer temperature, number of plots sampled and mean ± standard deviations of predictor variables at alpine, sub alpine, and boreal grassland sites along precipitation gradients (low [1] to high [4]) in southern Norway.
Fig 1.
Location of the twelve study sites along temperature and precipitation gradients in the fjord landscape of southern Norway.
Fig 2.
Overall ordination of the grid.
Canonical correspondence analysis (CCA) of measured biotic (green) and abiotic (black) environmental variables and alpine (▲), sub-alpine (●) and boreal (▼) sites along a precipitation gradient (1–4 from light to dark blue, see Fig 1) in southern Norway. LOI refers to Loss-On-Ignition, a measure of soil organic matter. Eigenvalues axis 1 = 0.472, axis 2 = 0.248, axis 3 = 0.182, axis 4 = 0.137. Only the two first axes are shown.
Fig 3.
Variation explained at broad and fine geographical scales.
Compositional variation in graminoid and forb species (% of total deviance [CCA] or variation [RDA]) explained by abiotic and biotic environmental variables, grouped and separately, at the a) regional/among site scale and b) local/within site scale when all sites are part of the same canonical correspondence analysis (CCA). Part c) shows parallel results for separate site-wise redundancy analyses (RDA) analyses for each of eleven grassland sites in southern Norway. LOI refers to Loss-On-Ignition, a measure of soil organic matter.
Fig 4.
Variation explained by abiotic vs. biotic variables.
Relative variation in species composition explained by abiotic (black) and biotic (grey) environmental variables in site-wise redundancy analyses (RDA) performed across eleven grassland sites in alpine, sub alpine and boreal sites along a precipitation gradient from low (1) to high (4) in southern Norway. LOI refers to Loss-On-Ignition, a measure of soil organic matter.
Table 2.
Regression slopes and associated p-values (* p < 0.05, · p < 0.1, no symbol = not significant) of relationships between variation in forb and graminoid species composition explained by local abiotic and biotic environmental variables in redundancy analyses (RDA) of local grassland species composition along broad scale temperature and precipitation gradients in southern Norway.
Table 3.
ANOVA estimates, F- and P-values of the relative proportion of the explained variation accounted for by biotic (vs abiotic) variables in redundancy analyses (RDA) of graminoid and forb species composition in grassland sites along temperature and precipitation gradients in southern Norway.