Figure 4. Relationships between species density (richness/area) and distance downstream (blue points & line) and cumulative richness (black line) for (a) Hjuksån and (b) Bjurbäcken. Species density regressions: Hjuksån (p = 0.0471, R2 = 0.21), Bjurbäcken (p = 0.694, R2 = 0.009). Relationships between similarity between vegetation communities and distance between all reaches for (c) Hjuksån and (d) Bjurbäcken. Linear regression: Hjuksån (R2 = 0.05, p = 0.003), Bjurbäcken (R2 = 0.092, p < 0.001).