ZLV Online

Influence of logging, possibly follow-up forestry measures on hydrology of forest and landscape are permanently the object of scientific research, economic policy and social activities. The article analyses the influence of timber harvesting on water yields at Česká Čermná (ČČ) and at Deštné (DS) in the Orlické hory Mts (Czech Republic). The results have been compared with similar data from Malá Ráztoka (MR) and Červík (ČE) experimental catchments in the Beskydy Mts (Czech Republic). Water yields were judged through runoff coefficients during growing seasons, before and after harvesting treatment. ČČ and DS runoff coefficients indicate changes of total gravity flow (overland flow + lateral subsurface flow + vertical flow). The total hillslope gravity flow was in accordance with the stormflow runoff from MR and ČE experimental watersheds. It is possible to induce that coefficients of both runoffs correspond and the both runoffs represent in fact direct runoff. Runoff changes were also shown by double mass curves – DSČ. Its curvature indicates runoff changes resulted from logging treatments or snow break damage. It was proved that runoff coefficient increase on experimental runoff areas after clearcutting really exists. Increase of runoff coefficient from stormflows was registered also after logging by strip cuts on the MR catchment, if more than 50% of the catchment was clearfelled and conversion of tree species composition from beech to spruce was performed. On the ČE catchment, where only half of the catchment was clearfelled, and regenerated (one catchment from two partial ones) water yield increase in stormflows has not come up.