Projects

Oak is one of the most valuable tree species in the Central Europe. However, establishing oak stands by traditional planting is very expensive. Since in most of the cases, the aim of growing oaks is the production of high quality timber, oaks are traditionally planted in high densities to facilitate self pruning. This has resulted plantation of stockings between 6000 and 10000 plants per hectare. For example, in Germany the costs of 1 ha oak afforestation can range between 7000 to 20000 Euro depending on the site conditions and required protection (e.g. fencing). These almost prohibitive costs have stimulated the search for alternative establishment practices.

One approach, which has become very popular, is the so-called “bio-groups”; where oaks are planted in clusters of 15-30 trees at different densities, and spacing between clusters represent the spacing between future crop trees. Many trials of such bio-groups have been established during the 1980s and 1990s. Some trials were developed in large openings after the catastrophic storm events in 1991 and 1999, where oak was to be introduced to create more wind-firm forests. Although many trials now exist, no comprehensive evaluation has been carried out involving all trials using techniques like meta-analysis. The project aims to evaluate these bio-groups on the basis of certain ecological and silvicultural parameters through a systematic meta-analysis.