Research Information System
Eruopean Water, vol.58, pp.281-286, 2017 (Peer-Reviewed Journal)
Forest ecosystems provide fresh water with best quality in sustainable manner but they consume huge amount of
water. Researchers apply different forestry practices to increase water yield by minimizing water loss through
evapotranspiration and maximizing amount of rainwater reaching soil surface in the watersheds. Studies showed that
water yield and nutrient losses increase after clear cutting. High nutrient concentrations in the streamwater cause
deterioration in the water quality. Therefore, objectives of this study were to investigate relationship between amount
of annual streamflow and nutrient outflux and quantify nutrient losses in three oak-beech mixed forest covered
watersheds. The experimental watersheds were located in Istanbul with sizes of 77.4 ha, 71.9 ha, and 17.5 ha. Water
samples were collected from the streams of the watersheds on weekly basis and analyzed for pH, electrical
conductivity (EC), total suspended sediment (TSS), chloride (CI-), calcium (Ca2+), magnesium (Mg2+), total nitrogen
(TN), sodium (Na+), potassium (K+), iron (Fe3+), aluminum (Al3+), ammonium nitrogen (NH4
+ - N), and sulfate
(SO4)2-. Regression equations were developed between annual water yields and nutrient outfluxes. Results showed
that there were significant relationships between annual water yield and nutrient outflux except for pH and EC and
these parameters showed increase with the increase in the streamflow discharge. This means that if the water yield
increases after timber harvest then water quality can be deteriorated in the watersheds.