F1 × F2 plane of CCA analysis (a) for eight dragonfly species, 31 sampling points and eight selected environmental variables, (b) shown as species richness. Legend: study sites (black circle symbols): IBR = Bijela rijeka River spring, SBR = Bijela rijeka River upper reaches, ICR = Crna rijeka River spring, SCR = Crna rijeka River middle reaches, CM = Crna rijeka River lower reaches, KR = Korana River, PP = Plitvica Stream, KM = Tufa barrier Kozjak-Milanovac, LB = Tufa barrier Labudovac, NOB = Tufa barrier Novakovića Brod. Microhabitats: S1 = cobbles, S2 = angiosperms, S3 = mosses, S4 = sand, S5 = silt with leaf litter. Environmental factors (green arrow symbols): T max = maximum water temperature (°C); O2 = O₂ (mg L⁻¹); pH = pH value; Con = conductivity (µS cm⁻¹); Vel = water velocity (m s⁻¹); Dep = water depth (cm); NO3 = nitrates (mg L⁻¹); NH4 = ammonium (mg L⁻¹). Species (red triangle symbols): Gom vul = Gomphus vulgatissimus, Ony for = Onychogomphus forcipatus, Cor bid = Cordulegaster bidentata, Ort coe = Orthetrum coerulescens, Cro ery = Crocothemis erythraea, Pla penn = Platycnemis pennipes, Cal vir = Calopteryx virgo, Coe pue = Coenagrion puella.