Intensive Monitoring of Forest Ecosystems in Europe : Technical Report 2000

Brüssel

2000

191 S.

zahlr. Lit. Ang.

Bandaufführung

13834

76831

Apart from an overview of the implementation of the Intensive Monitoring Programme of forest ecosystems in Europe and the various methodological aspects involved in data evaluation, this Technical Report gives information on results obtained in surveys on crown condition, soil condition, foliar condition, atmospheric deposition and soil solution chemistry. It also includes examples from results related to remote sensing. The major aim of this year's reprot was to gain insight in element concentrations in view of critical chemical values and in relationships between results from the various surveys and environmental factors, in comparison to previously obtained results. Examples of aerial photography show that this technique can successfully be used to gain information on the representativity of stand characteristics, such as crown condition, stand height and stand structure, within the plot in comparison to the area surrounding the plot including time series of those characteristics. Major conclusions for the different surveys are: - Both bulk and total deposition of N appeared to be higher than S deposition at nearly all the plots in 1997 and the average calculated total N deposition was approximately twice the S deposition. Atmospheric deposition was significantly influenced by the geographic region and to a lesser extent by rainfall, altitude and tree species. - Stand age alone explained 5-36% of the variation in crown condition, depending on tree species. Apart from stand age, 15-30% of the variation in defoliation could be explained by the variation in precipitation, temperature, N and S deposition and foliar chemistry. - At approximately 30% of the stands, the nutrient status of the foliage can be judged as insufficient and unbalanced for at least one nutrient. Atmospheric deposition, meteorological parameters, soil chemistry, and site characteristics all contributed to the explanation of foliar nutrient concentrations. The percentage variation accounted for generally decreased going from N> Mg> S> Ca> K> P. The foliar N and S concentrations of the coniferous species, especially pine, were significantly related to the N and S deposition. - Nitrogen pools, in the organic layer of forest soils varied mostly between 100 and 250 kg.ha®Ü.yr®Ü. Considering the net N input by deposition, a time interval of 10 years might give a significant difference in N pools for approximately 25% of the plots. Approximately 30-50% of the variation in element pools in the organic layer was mostly explained for by various stand and site characteristics, precipitation, temperature and pH. - Concentrations of NO3 and ratios of Al to Ca+Mg+K, above levels that are indicative for adverse effects, occurred in the subsoil at some 10 - 40% of all plots, respectively. Those plots were manily located in a transect from Finland to Spain. The variation in concentrations of major ions in the soil solution could to a large extent be explained by differences in atmospheric deposition and to a lesser extent by variations in precipitation and soil chemistry.