Considering the fragility of the Mediterranean environment, there is an increasing need to improve the knowledge of this forest environment. The aim of this study was to examine the effects of air pollution on the forest ecosystem’s condition by analyzing tree vitality. The study area was chosen to represent the most important and the most common species in Mediterranean forest ecosystems of the Eastern Adriatic coast. Quercus pubescens, Quercus ilex, Pinus halepensis, and Pinus nigra plots were equipped with rain collectors and dendrometer bands. Sampling, measurements, and analyses of atmospheric deposition, foliar nutrient, defoliation, and growth were all carried out. Results showed that actual N deposition loads were the lowest in Aleppo pine forest and the highest in holm oak forests. This, however, did not have an effect on the concentrations of N in foliage. Most elements’ concentrations were in the plausible range. No relevant differences in mean defoliation between the plots were observed. The plots with a lower percentage of basal area increment (BAI%) were found to have lower defoliation. The research was conducted to bridge the gap in the knowledge of air pollutants and vitality indicators in different forest types. These findings are a valuable contribution to the sustainable forest management of Mediterranean forest.

The Mediterranean region, with its unique ecological characteristics, is particularly sensitive to global environmental changes, including climate change and impact of air pollution. Although Aleppo pine and black pine forests are the most abundant on the eastern Adriatic coast, atmospheric deposition in these forests is poorly studied. Changes in the chemical composition of precipitation as it passes through the tree canopy can lead to soil and groundwater eutrophication, and soil acidification, which affects plant vitality. In this study, the dynamics of ion deposition in Aleppo pine forest ( Pinus halepensis Mill.) and black pine forest ( Pinus nigra Arnold) on the eastern Adriatic coast are investigated, focusing on throughfall and bulk open field depositions. The aim of our research was to fill the gaps in understanding the influence of tree canopies on deposition fluxes in two different Mediterranean pine stands and to compare total inorganic nitrogen loads with critical loads. Over a period of two years, bulk open field precipitation and throughfall were sampled, measured and analysed using the ICP Forest methodology. The results indicate significant differences in ion deposition between bulk open field and throughfall, with throughfall showing higher values for almost all ions. The highest enrichment ratio was determined for K+. + . The comparison of the actual inorganic nitrogen load with the critical nitrogen load for Mediterranean pine forests revealed that the inorganic nitrogen load exceeded the critical load in the Aleppo pine forest. Ion deposition increased in the throughfall compared to bulk precipitation, which can be attributed to the seasonality of precipitation, including leaching and long dry periods. These findings enhance our understanding of ion deposition fluxes in vulnerable Mediterranean pine ecosystems and emphasize the need for long-term research on this topic in the actual changing environmental conditions.

This study investigated the hydrochemical linkage between rainwater and stream water in an Aleppo pine-dominated Mediterranean karst catchment in Croatia during 2020–2022, focusing on ion sources, seasonal patterns, and processes governing the transformation of atmospheric inputs into stream-water chemistry. Rainwater reflected mixed atmospheric inputs, with sea-salt fractions accounting for 94.8% of Cl⁻ and 97.9% of Mg²⁺, whereas 97.5% of Ca²⁺ and 79.2% of K⁺ originated from non-sea-salt sources. Stream water was substantially more alkaline and mineralised, with a higher pH (8.23 vs. 6.53), electrical conductivity (327 vs. 19.63 µS cm⁻¹) and Ca²⁺ concentrations (65.08 vs. 6.22 mg L⁻¹). These differences reflect carbonate weathering during subsurface flow, whereby the dissolution of calcite and dolomite releases Ca²⁺ and Mg²⁺, increases alkalinity and buffering capacity, and results in approximately tenfold-higher stream-water Ca²⁺ and Mg²⁺ concentrations. Seasonal variability was evident, with ion enrichment during low-flow conditions and dilution during wetter periods. Limited synchronous hydrochemical correspondence between rainwater and stream water indicates that atmospheric inputs are modified during catchment transport. Overall, atmospheric deposition provides the initial hydrochemical signal, whereas carbonate weathering, hydrological flow paths, and seasonal biogeochemical processes are the predominant controls on stream-water chemistry.