Possibilities for estimation and silvicultural influencing the contention in young mixed stands of beech and Douglas fir
1999
Bommer, S. | Weihs, U. | Beuke, H.
Covering more than 1,5 % of the total forest area Douglas fir (Pseudotsuga menziesii (Mirb.) Franco) is today the most important foreign species in Germany. For reasons of stability and ecology Douglas fir is preferably mixed withEuropean beech (Fagus sylvatica L.), which is the most competitive indigenous species in Germany. But even compared to European beech Douglas fir shows a superior growth. The authors studies reveal that the two species show different reactions to differing degrees of shelter. While the best growth of European beech requires a medium shelter, Douglas fir looses competitiveness as the shelter turns more umbrageous. During the investigation the authors were concerned with the problem of estimating the competition between the two species in quantity the angle alpha was found appropriate to record the competition between species. Close functional correlation between the investigated parameters of competition could be proved by regression analysis. Therefore it is possible to concentrate on the main competitor with the highest angle alpha, which can be ascertained easily on the basis of distance and difference in height. Results show that a beech can only tolerate two or three Douglas firs among its next five competitors if there is a medium or intenses shelter. Because of the outstanding competitiveness of Douglas firs next to a beech under the conditions of a light shelter wood. According to these results mixed stands of European beech and Douglas fir should be planted or naturally regenerated under the conditions of a medium shelter with a mean interconnecting number at least of 2:1 to the advantage of beech.
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