Integrated impact of sulphur and nitrogen deposition and ozone on forest ecosystems in Lithuania, 1995–2015

Abstract

The present study considers temporal variability in concentrations of the throughfall fluxes and bulk fluxes of sulphate, nitrate, and ammonium in precipitation in Lithuania evaluated employing a non-parametric Mann-Kendall test along with Sen’s slope estimator during the period 1995–2015. Decreased air concentrations of sulphur species and ammonium as well as their deposition were the main drivers of the reduction of mean defoliation of Scots pine trees in Lithuania. Their effect on Norway spruce crown defoliation was less expressed, but no effect of acidifying species and surface ozone was detected on birch tree crown defoliation. The established relationships revealed that a deterioration of the health of coniferous tree species, first of all Scots pine, could be expected only in forest where the deposition of the acidifying species exceeded the critical loads.