Does forest harvesting change the runoff quality?

Document Type : Research Paper


1 PhD Student of Forest Engineering, Faculty of Natural Resources, University of Tehran, I. R. Iran

2 Prof., Faculty of Natural Resources, University of Tehran, I. R. Iran

3 Associate Prof., Faculty of Natural Resources, University of Tehran, I. R. Iran


Forest harvesting by cutting off the nutrient cycling processes affects the water quality causes the soluble nutrients in the plant to be washed out and flowing through the soil to the river. The type and method of harvesting are important factors in the amount of nutrients get out from the area. The present study aims at investigating the effect of forest harvesting on runoff quality components in plot scale (2m*1m) with four replicates in tow slope scale (0-20%, 20-40%) in the northern forests of Iran during December 2014, December 2015. The rain depth was measured by using a rain gauge installed in the study area. Statistical analysis was conducted to evaluate the effect of forest harvesting on water quality. Samples were analyzed for EC, TDS, pH, anions (Chlorine, sulfate, bicarbonate) and cations (Calcium, magnesium, sodium, and potassium). Kruskal- Wallis Test at 0.01 significance levels was used. The results of the study showed that there was significant effects of forest cover and slope (P <0.01) on EC, TDS, anions and cations among four sites (without logging, under logging selective cutting, without canopy cover and skid trail). Spearman correlation coefficients between anions and cations were determined. There was significant correlation between Calcium, magnesium at 0.01 levels and sodium, potassium at 0.05 levels of four sites. An attempt has been made to develop the linear equations among cations parameters. The usefulness of these linear regression equations in predicting the water quality is an approach, which can be applied in any other locations. The main disturbance features of forest harvesting are the changes in vegetation characteristics that reduce the rainfall and protect soil and water. Management approaches such as application of precise harvesting can effectively protect the soil and stream water quality.


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