Slash-pile burning impacts on the quality of runoff waters in a Mediterranean environment (Croatia)

Abstract

Slash-pile burning is a frequent land management practice implemented across the Mediterranean. However, the impact of this practice on runoff waters has often been neglected. To address this issue, two experimental burns were conducted: one with moderate (MS) severity, and another with high (HS) severity, to evaluate the impact of different types of slash–pile on the quality of runoff waters. An unburned (UB) treatment was also considered in this study, to evaluate the impacts of slash–pile burning per se. Treatments were established on a slope terrain (∼18°) characteristic of the Adriatic coast. During the two-year study, runoff and erosion samples were collected 22 times after major rainfall events. Aside from runoff, erosion, and total carbon in sediments (TC) were determined, as well as various water quality parameters, including, pH, electrical conductivity (EC), and Br¯, Cl¯, SO42¯, PO43¯, F¯, K+, Na+, Ca2+, and Mg2+. Overall, water quality parameters were more affected shortly after burning, while runoff and erosion were more dependent on precipitation patterns. TC in sediments was higher in HS than in MS, the highest values being observed in the last sampling events for both burned treatments. Regarding runoff water quality, the effects were more pronounced at HS, even if the hydrological response was stronger at the MS. The UB treatment showed significant changes in runoff water quality following major rain events, which was attributed to soil saturation. Our results suggest that slash pile burning has adverse effects on runoff waters, so it is recommended for biomass to be used in other ways, especially in the context of soil and water conservation.