In this review, the unique features and facts of long-term experiments are presented. Long-term experimental plots provide information of forest stand dynamics which cannot be derived from forest inventories or small temporary plots. Most comprise unthinned plots which represent the site specific maximum stand density as an unambiguous reference. By measuring the remaining as well as the removed stand, the survey of long-term experiments provides the total production at a given site, which is most relevant for examining the relationship between site conditions and stand productivity on the one hand and between stand density and productivity on the other. Thus, long-term experiments can reveal the site-specific effect of thinning and species mixing on stand structure, production and carbon sequestration. If they cover an entire rotation or even the previous and following generation on a given site, they reveal a species' long-term behaviour and any growth trends caused by environmental changes. Second, we exploit the unique data of European long-term experiments, some of which have been surveyed since 1848. We show the longterm effect of different density regimes on stand dynamics and an essential trade-off between total stand volume production and mean tree size. Long-term experiments reveal that tree species mixing can significantly increase stand density and productivity compared with monospecific stands. Thanks to surveys spanning decades or even a century, we can show the changing long-termperformance of different provenances and acceleration of stand production caused by environmental change, as well as better understand the growth dynamics of natural forests. Without long-term experiments forest science and practice would be not in a position to obtain such findings which are of the utmost relevance for science and practice. Third, we draw conclusions and show perspectives regarding the maintenance and further development of long-term experiments. It would require another 150 years to build up a comparable wealth of scientific information, practical knowledge, and teaching and training model examples. Although tempting, long-term experiments should not be sacrificed for cost-cutting measures. Given the global environmental change and the resulting challenges for sustainable management, the network of long-term experiments should rather be extended regarding experimental factors, recorded variables and inter-and transdisciplinary use for science and practice.

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Summary: The global need to increase sustained forestry value production requires an operational silviculture and a practical method for controlling tree growth, especially that of target trees. The target tree management system has been designed for this purpose. It is applicable as a decision support tool in stands of any size and structure, including pure and mixed stands.For controlling the growth of selected target trees, only a few tree parameters (age, height and diameter) need to be taken from sample target trees and compared to site‐specific growth norms. These target tree norms describe the optimal growth of target trees towards a specified production goal, easily modified by the forest owner to his own requirements.For each stand and tree species, the target tree management system delivers target tree related information on vitality, production risks, thinning volume within the next 10 years, value development, and the time required to reach the target diameter. Stands may be grouped and evaluated according to the importance of these criteria. This may be a strategic help towards solving the problems of timber market policy in the next decades.The system is also suitable for description of growth and yield in long‐term experiments, especially those involving special treatments and the changing influence of climate and soil conditions, and provides for data transfer to the forest owners.

Growth and value production of Douglas-fir under varying stand densities The investigation is focused on the effects of initial tree number and thinning on growth and value performance of Douglas-fir stands. Data base is a coordinated Douglas-fir spacing experiment in South Germany, started 40 years ago and comprising variants of tree numbers with 500, 1,000, 2,000 and 4,000 Douglas-firs per hectare. The treatment was performed according to a standardized experiment program. The results show that at low initial tree numbers, the diameter on breast height (DBH) of (pre)dominant trees at the beginning of the observations (with 12 m top height) is bigger than at higher initial plant numbers. Accordingly, the quotient of height (H) to DBH (as an indicator for tree's static stability) is lower. The further development of DBH and H/DBH quotient is decisively determined by stand treatment, which superimposes the effect of the initial tree number. The total volume growth shows a clear differentiation, too, the variants with initially high tree numbers appearing on top. In the monetary analysis, this ranking is reversed: despite a supposed inferior wood quality, the variants with lower initial tree numbers clearly outperform the ones with higher numbers in terms of value. From these results, the following silvicultural recommendations for Douglas-fir can be derived: the initial tree numbers should be in the range from 1,000 to 2,000 plants per hectare. On technically not accessible sites, even lower tree numbers may come into question. The strong influence of stand treatment on DBH and H/DBH development highlights the problem of postponed thinnings, for this causes growth and stability losses even under favorable starting conditions in terms of competition.

Waldbau mit Douglasie in Deutschland und in Frankreich Der erwartete Klimawandel macht die Douglasie (Pseudotsuga menziesii [Mirb.] Franco) zu einer vielversprechenden Option für die Waldbewirtschaftung in Mitteleuropa. Die Art ist resistenter gegenüber Trockenheit als zum Beispiel die Fichte, wächst sehr gut und liefert wertvolles Sägeholz mit überlegenen technischen Holzeigenschaften. Die über ein Jahrhundert vor allem in Frankreich und in Deutschland gesammelte Erfahrung in Forschung und Praxis hat substanzielles, evidenzbasiertes waldbauliches Wissen zur Bewirtschaftung der Douglasie in Europa geschaffen. Der Artikel hat zum Ziel, die wichtigsten Aspekte darzustellen. Während die mit relativ hohen Kosten verbundene Pflanzung bislang die gebräuchlichste Begründungstechnik in Europa war, wird das offensichtliche Potenzial der natürlichen Verjüngung mit grosser Wahrscheinlichkeit an Bedeutung gewinnen. Allerdings wird die Wurzelentwicklung junger Bäume sowohl durch Überschirmung als auch durch seitliche Konkurrenz negativ beeinflusst. Wenn die Douglasie unter Schirm verjüngt werden soll, muss die Dauer der Überschirmung kurz gehalten und die seitlichen Konkurrenten frühzeitig und entschlossen entfernt werden. Das Durchmesserwachstum lässt sich durch geeignete Pflanzabstände, Durchforstung und die Wahl der Produktionszeiträume gezielt steuern. Die Holzqualität kann durch die Auswahl von Z-Bäumen und eine Ästung verbessert werden. Um den Anteil an qualitativ minderwertigen schwachen Sortimenten klein zu halten, kann ein längerer Produktionszeitraum in Verbindung mit grösserem Zieldurchmesser als Bewirtschaftungsoption in Betracht gezogen werden. Allerdings sind längere Produktionszeiträume ausnahmslos mit höheren Risiken verbunden, insbesondere nimmt das Sturmschadenrisiko mit der Baumhöhe progressiv zu. Im Zusammenhang mit dem Risikomanagement und der Integration der nicht einheimischen Douglasie in naturnahe Bewirtschaftungssysteme sind die Begründung und die Bewirtschaftung von Mischbeständen von grosser Bedeutung.