Dependence of the average and 95% confidence intervals for the number of recorded individuals (NL) of D. dahli (solid lines) and D. portschinskii (dashed lines) at a plot during a given session on: a: distance from the brook (m), b: year, c: air temperature (°C), d: days passed after 1st April, e: substrate type and f: average slope index on the 3 cm pixel scale (averaged for a plot).