The growth of introduced tree species in Baden-Wuerttemberg.
Searching for possibilities to adapt our forests to the climate change, the question of the suitability of introduced tree species is discussed. To get an idea about the growth performance of these tree species under present growth and climate conditions, but also to examine the success of such experiments, the existing database of introduced tree species available at the Forest Research Station of Baden-Wuerttemberg was evaluated (Fig. 1). 15 out of the 40 introduced tree species with 431 plots being available on the data base, proved to be suitable for a statistical evaluation (Tab. 1). These experiments were analysed with regard to the relation of top height and age (using the Sloboda function, Tab. 3) respectively with regard to the relation of top height and total volume production (using a multiple polynomial regression, Tab. 4). The results gained for Abies grandis (Fig. 2-Fig. 4), Larix kaempferi (Fig. 5-Fig. 8) and Quercus rubra (Fig. 9-Fig. 14) are presented more detailed in the paper. Moreover, top height site indices and total volume production of some of the introduced species were compared to that of adjacent experiments with the "main" tree species Picea abies, Abies alba, Pseudotsuga menziesii, Fagus sylvatica and Quercus spec. (Tab. 2, Fig. 15 and 16). The comparison revealed that with respect to growth performance, Abies grandis and Pseudotsuga menziesii are clearly superior. Under comparable site conditions, Larix kaempferi reaches similar top heights like Picea abies and Abies alba, but a significantly lower total volume production. Quercus rubra equals Fagus sylvatica with regard to top heights as well as total yield and outperforms the native oak species. All the other introduced tree species for which this comparison could be made, were inferior in terms of productivity to the main tree species.