Fig 1.
Fig 2.
Nested subcatchments in Stordalen (borders in black) delineated using the D8 algorithm.
Fig 3.
Boxplot of mean monthly NDVI values for the 16-day composites at 250 m resolution for the years 2006–2012 (adapted from ORNL [59]).
Annual mean NDVI for the catchment is shown with subcatchment boundaries in black overlain to annual variation across subcatchments.
Fig 4.
Scatterplot of (a) mean annual dissolved organic carbon (DOC) concentrations and (b) flow-weighted mean annual DOC against NDVI per subcatchment. The DOC regression line shows Y = -41.765x + 41.971, R2 = 0.137 and for DOCqwc Y = 0.0042x + 0.7208, R2 = 0.114.
Fig 5.
Scatterplot of (a) mean annual dissolved organic carbon (DOC) concentrations and (b) flow-weighted mean annual DOC against Slope. The DOC regression line shows Y = -0.5047x + 14.816, R2 = 0.461 and for DOCqwc Y = 0.2789x + 6.9655, R2 = 0.082.
Fig 6.
Scatterplot of (a) mean annual dissolved organic carbon (DOC) concentrations and (b) flow-weighted mean annual DOC against Elevation per subcatchment. The DOC regression line shows Y = -13.209x + 628.36, R2 = 0.374 and for DOCqwc Y = 8.853x + 408.67, R2 = 0.099.
Table 1.
Correlation matrix of average monthly DOC concentration with fixed land cover proportion per subcatchment per year together with the seasonal maximum NDVI.
Slope (n = 50), Mire (n = 50), Forest (n = 50), Lake (n = 9), NDVI (n = 50), Elevation (n = 50), and DOC (n = 218).
Table 2.
LMER model equations for DOC concentration Stordalen catchment.
Models are ranked by marginal and conditional R squared values. Slope (n = 50), Mire (n = 50), Forest (n = 50), Lake (n = 9), NDVI (n = 50), Elevation (n = 50), and DOC (n = 218).
Table 3.
Significance of fixed effects terms of the full model.
Slope (n = 50), Mire (n = 50), Forest (n = 50), Lake (n = 9), NDVI (n = 50), and DOC (n = 218).
Table 4.
Correlation of fixed effects for the full model.
Slope (n = 50), Mire (n = 50), Forest (n = 50), Lake (n = 9), NDVI (n = 50), Elevation (n = 50), and DOC (n = 218).
Fig 7.
Relative DOC contributions from subcatchments to riverine DOC in Stordalen from Model 1.
Coefficients and the intercept (52.9) were extrapolated from LMER Model 1 to each pixel using the fixed terms of the model equation. DOC loss (denoted in blue) occurs in lakes and where steep slopes occur with forest land cover.
Fig 8.
Relative DOC contributions from subcatchments to riverine DOC in Stordalen from Model 2.
Coefficients and the intercept (1.4) were extrapolated from LMER Model 2 to each pixel using the fixed terms of the model equation. DOC loss (denoted in blue) occurs where lakes and forest land cover dominate.
Fig 9.
Relative DOC contributions from subcatchments to riverine DOC in Stordalen from Model 3.
Coefficients and the intercept (17.3) were extrapolated from LMER Model 3 to each pixel using the fixed terms of the model equation. DOC loss (denoted in blue) occurs where lakes and high elevation combine with forest land cover.