The project gives a retrospective view of the development of forest site productivity in Europe. Starting from the middle of the last century, forest research organizations installed permanent research plots, analyzed trees, and conducted inventories to investigate long-term growth of forests. In recent decades the debate on forest decline and possible climatic change emphasized the importance of growth studies. Recent investigations in European forests indicate positive as well as negative changes in forest site productivity. In contrast to intensive discussions about forest decline in the 1980s, several growth studies show that actual forest growth may have increased on specific sites. Growth parameters such as height, diameter and volume have been investigated.
Three data sources will be used in the project: tree analysis data, permanent plot data, and inventory data. Since mainly existing data will be analyzed some limitations have to be accepted: Data may not always be representative for larger areas, stand structure and stand history may not always be well documented in all details. Growth trends are defined as deviation of actual growth from expected growth over several decades. The definition of expected growth is therefore important. Past experience on comparable sites will be used as a "growth reference".
The focus of the European Forest Institute's project is the evaluation of available data on a European level. Data will be checked, evaluated and interpreted by each scientist individually according to common standards. Standardization of methods and presentations are required. Since methods of collecting data differ considerably, evaluation methods have to be adapted to each case. Some standards are recommended. The results of the project will be published in a report consisting of the individual contributions.
Knowledge about European forest growth trends is necessary for sustainable forest ecosystem management and for forest industries. Besides this, growth reactions could be useful to identify and quantify possible environmental changes in their spacial and temporal extent and information about past effects of environmental changes are a base for prediction of future development. The target group for the project's results are scientists, forest land owners, forest managers, and decision makers as well as the public interested in environmental questions.
Key words: growth trend, Europe, environmental changes.
Correspondence: Heinrich Spiecker, Institut für Waldwachstum, Bertoldstr. 17, D-79085 Freiburg, Germany
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E-mail: instww@sun1.ruf.uni-freiburg.de