The objective of this illustrative study was to obtain realistic data about the age and period of

hydrologic maturity of forest stands in order to use these indicators for planning the forest

management activities in water catchment basins located to the north of Istanbul. On the basis of data

and aggregate data summaries obtained from numerous studies in Central Europe, the Balkans,

Southern Ukraine, the lower forest vegetation zone of Caucasus, and Northern Asia Minor, the first

stage of the study involved the development of a hypothetical hydrologic water budget model of the

dominant tree species in the studied forests. The next stage was to calibrate this model using data from

specific climate, hydrologic and soil studies in the area under investigation. The third stage covered the

comparison between the actual and optimal age stand structure in the studied catchment area, and

these were used to calculate several variants of hypothetical water yield. On the basis of the upper limit

of the period of hydrologic maturity and the forest management analysis made, the harvest rotation of

the hydrologic forest management class was determined. The final part of the study used the already

determined period of effective precipitation and dynamics of soil moisture during the growing season

to make recommendations for the forest management practice in the studied area.

Key words: Forest management, water yield, temperate zone.