Many previous studies evidenced very high levels of air pollution by ozone between the North Italy (Lombardy) and the Southern Switzerland (Canton Ticino). These levels are mostly attributed to the influence of the large urbanized area of Milan and to the urban and industrial settlements in the Po Valley. Recent researches revealed the existence of spread foliar ozone-like symptoms in many native plant species, both in the Swiss and in Italian sector. Experiments carried out in open top chambers in Canton Ticino allowed us to attribute the foliar symptoms to the ambient air pollution levels

The general conclusions of Warsaw ILTER meeting was that following ILTER philosophy, ecological processes integrity can be maintained on the basis of profound knowledge on the rate of changes, hierarchy of driving forces and resistance and resilience of ecosystems. To achieve such complex understanding of these processes there is a need , first to collect and analyze broad spectrum of data possibly standardized by methodology and next permanently exchange information with coordinators from other countries and regions. As a consequence the participants suggested to extend the initial number of 6 sites situated mostly at National Parks and MAB Biosphere Reserve by the new sites representing broader scope of ecosystems and wider range of its anthropogenic modifications. This should allow to define the regional hierarchy of factors deteriorating the ecological systems and create better scope for comparative studies for global environment

Results on germination, growth and mortality of Norway spruce seedlings during period 1994-2000 in various types of soil cover were summarized and evaluated. The years 1992 and 1995 were recorded as high seed production years, while the year 2000 is considered as the low seed production year. In 1999 natural seedlings from various soil covers were examined for lateral root and root tip development. The results of germination and surviving of Norway spruce seedlings are discussed in relationship with the stage of the decline of Norway spruce ecosystems

Determination of the streses operating on a forest ecosystem demands the use of several bioindication methods. Air quality indicators were assessed from an inventory of forest decline based on the assessment of tree crowns and lichens. Photosynthetic pigments, ascorbic acid and major macro nutrients were studied in mountain pine (Pinus mugo Yurra) needles as indicators of physiological and biochemical stress. Analyses were carried out at selected forest plots and transects in predominantly unpolluted areas within Triglav National Park, Julian Alps, Slovenia. It was assumed that air pollutant input in forest ecosystems is of two kind, e.g. local from the air pollutin sources in the valleys on the North-West part of tha national park and transboundary source at high altitudes

While nitrogen input exceeded the critical loads of the WHO (1995), nitrogen deficiency and nutrient imbalances were verified by needle analyses. The atmospheric input of inorganic nitrogen was higher than the nitrogen output in 50 cm soil depth. A tracer experiment with 15N helped to prove that not more than half of the applied nitrate could be discharged. This allows the conclusion that nitrogen is stored in the system and that the site cannot yet be said to be saturated with nitrogen. The same result was also obtained by modelling

Critical loads were estimated for over more than 1400 receptors supporting forest vegetation in northern Belgium using simple mass balance method. Necessary data were derived from old historical soil database, recent data from forest surveys, meteo data, level I and II plots and regional studies concerning elemental sequestration in woody biomass. Deposition estimates were performed with the OPS-model, which had been validated with deposition measurements of N and S in 6 level II plots over the period 1994-1998. In addition, an edge enhancement factor was calculated to account for enhanced deposition in plots situated in forest edges

Soil microorganisms are important for plant growth and beneficial for the nutrition and the development of a variety of soil animals. Together with soil invertebrates they also improve nutrients availability in soils. Although not frequent in Europe , magnesite emissions can affect the nutritional status of the vegetation and the survival of soil microorganisms as well as other biota locally, and thus may be crucially responsible for the quality of the entire biotic system. The observed gradients of soil microbial characteristics reflect the physico-chemical properties of soils around the magnesite plant and may be used to predict transitory changes during amelioration

Phenotypical differentiation between and within populations was observed. During the last decade, vitality decreased for both species in the observation plots in accordance with the general trend in Germany. Differences between the species were detected for single symptomatic traits like bark necroses. The genetic analyses with isozyme markers as well as cpDNA haplotypes resulted in remarkable differences between species

Since 1990 the investigations of quality of some components of nature environment were carried out on selected permanent plots in Protected Landscape Area Ponitrie focused on pollutant contents. The increased concentration of pollutants in precipitation from the top of the Vtacnik Mts. indicates firstly the effect of the nearby thermal power station, secondly documents an increased immission load on forest ecosystems in ridge positions of these mountains

Acidification of forest soils is dependent on the tree species for several reasons. One reason is that the deposition to deciduous tree species normally is considered lower than to coniferous tree species. This study therefore considers the differences in deposition to different tree species in Denmark. Canopy throughfall and precipitation were collected during the period 1986 to 1999 at three trial species experimental sites in Denmark. At each site the species Norway spruce, sitka spruce, Douglas fir, beech and oak were studied. The paper presents and discusses the differences in canopy exchange processes and dry deposition in different tree species and at different locations