Chemistry of rainfall and its components under pine forests in Dohuk governorate

الملخص EN

The study was carried out at Zawita pine forests (Pinus brutia Ten.) during the water-year 2010-2011.

The area is located about 17 km northeast of Duhok city in Kurdistan Region of Iraq.

Two forest stands were selected, the area for each one was 900 m2.

One for the natural pine forest and the other for the artificial pine plantation.

The results showed that the concentration of cations and anions increased after the rainfall passed through the canopy and flowed via the bole.

The sequence of total cations and anions concentration decreased in the order of: stemflow > throughfall > gross rainfall.

Cations concentration for gross rainfall in natural pine forest and artificial pine plantation decreased in the order of: Ca2+> Mg2+> Na+ > K+, were 28.6, 8.89, 7.11 and 5.43 mg/L; 27.44, 8.27, 5.76 and 4.23 mg/L respectively.

But this sequence changed in throughfall and stemflow in both stands to become Ca2+> Mg2+> K+ > Na+, were 66.21, 25.32, 16.9 and 11.15 mg/L; 98.80, 36.45, 25.01 and 16.6 mg/L in natural pine forest, while in artificial pine plantation were 46.64, 19.82, 11.27 and 9.29 mg/L; 75.06, 25.20, 17.48 and 13.21 mg/L respectively.

Anions in gross rainfall in both stands decreased in the order of: HCO3 -> Cl-, were 75.95 and 32.79 mg/L in natural pine forest while for artificial pine plantation were 72.40 and 31.73 mg/L respectively, and the sequence in throughfall and stemflow in both stands of natural pine forest and artificial pine plantation were 141.92 and 70.56, 127.45 and 63.05mg/L for throughfall and for stemflow were 197.07 and 83.84, 174.7 and 77.32 mg/L respectively.

The results also indicated that the pH values slightly increased in throughfall and decreased in stemflow as compared with gross rainfall.