For several decades, acid deposition has had a major impact on forest ecosystems of the Northern Hemisphere, particular in areas having substrates with low base content. During the last 20-25 years, the deposition of sulphate (S04) has decreased in many areas Europe [1]. However, the nitrogen (N) deposition (nitrate (N03) and ammonium (NH4)) remains high. Subsequent oxidation of NH4 increases the acid load for terrestrial and aquatic ecosystems. Although S04 deposition and associated H+ deposition have decreased, many ecosystems still receive high loadings of acidity. According to the data provided by the European EMEP Monitoring Center, depositions of ammonia on the territory of the Republic of Moldova are 136-240 and 85-148 mg/m2 depending on the EMEP grid cell under survey. In the years 90th of the last century, the values of oxidized and reduced nitrogen stood at 7-30 kg/ha. Acidification, eutrophication are base effects affecting vegetation forest ecosystems. Assessing of integrated index of eutrophication of the ecosystems was based on critical loads concept (which has been elaborated to assess air pollution reduction strategies, becoming a modern method for the estimation of potential harmful effects of atmospheric pollutants on ecosystems) [2]. Critical loads are defined as “a quantitative estimate of an exposure to one or more pollutants below which significant harmful effects on specified sensitive elements of the environment do not occur according to present knowledge” (UN-ECE, 1996). Critical loads for nutrients for the territory of the Republic of Moldova in EMEP 50x50 grid cells have been calculated by the following: CLnut(N)= Ni + Nu +Nle (acc) / (1 - fde), where: Ni - Annual rate of nitrogen immobilization in root zone ; Nu - Annual rate of nitrogen uptake by vegetation harvesting. For all types of vegetation (semi- natural vegetation, forests), the annual averaged critical levels for NO2 and SO2 stand at 20 μg/m3 and 30 μg/m3 respectively. Critical levels for NH3 for time period – annual mean and 24-hour mean stand at 8 μg/m3 and 270 μg/m3 respectively. Atmospheric air quality in rural areas as assessed by calculating the dispersion of pollutants from local sources. In the figure below is presented the calculation based on characteristic for sources of pollution (technological, meteorological, geographical location) data from Călărași area. Fig. The isolines of nitrogen dioxide concentration for the most unfavorable conditions of pollution According to the Program “Ecolog” calculations, dispersion NOx emissions from local sources for protected areas the range vegetation are from 6.5 to 10 μg/m3,that is ten times smaller than the critical value, which indicates a significant NOx pollution on the environmental components studied. Ion exchange to environmental and forest vegetation including CL calculation of pollutants require a database by about 60 environmental indicators. If the nutrient cycle is modelled, as in the SAFE model, data are needed on litterfall rates, root turnover rates, including the nutrient contents in litter, and fine roots. Such data are highly dependent on tree species and site conditions, tape of soils. Compiling of such data allow us to perform mitigation of pollution at a higher level of knowledge.