Eight years of integrated monitoring in Alpine forest ecosystems of Trentino and South Tyrol, Italy

After the acute emergency of decline in European woodland at the beginning of 1980’s, forest health was the subject of several studies in Trentino and South-Tyrol. Since 1992 investigations focused on an integrated monitoring under the UN-ECE-ICP programme in 4 selected areas, 2 in subalpine Norway spruce woodland (Lavazè Pass and Renon), and 2 in thermophilous Pubescent oak woodland (Pomarolo and Monticolo). The interdisciplinary programme of integrated monitoring aimed to investigate the state of alpine semi-natural forests in relation to air pollution, anthropogenic stresses, climate changes and trophic-energetic balances. Assessment of forest health by means of crown conditions showed very low levels of defoliation and discoloration in the subalpine areas, while in the other ones the same parameters had slightly higher values. Every year and in all the sites the mean percentages values were always in class 0 and class 1, hence indicating no danger. Weather patterns showed the presence of occasional water deficit, albeit general trends were not observed. High level of pollution were never detected while the level of acidity in rainfall has been slightly decreasing in all the investigated plots. Only ozone showed higher values than normal but there was no correlation with any damage. Foliar mineral nutrient contents ranged quite always within the threshold level. Because of the few years of observation and the absence of relevant stress, it is not possible to get any indication about the relationship between the forest health status and the fungi community composition. The presence of some anomalous data and the growing concern on climate change give reason to the importance of a continuous monitoring action acquiring of comparable set of data, in order to get a better understanding of forest ecosystems response to stress and make progress in general ecological knowledge.