Neue Ernährungskennwerte für die in Mitteleuropa eingebürgerten Baumarten Douglasie, Roteiche und Robinie – Eine statistische Herleitung aus VAN DEN BURG’S Literaturzusammenstellung

Title of the paper: New nutritional threshold values for the in central Europe established tree species Douglas Fir, Red Oak and Black Locust – A statistical derivation from VAN DEN BURG’s literature compilation. For the main tree species (GÖTTLEIN et al., 2011) as well as for many less common tree species (GÖTTLEIN and ZEHLE, 2018) of Central Europe already nutritional threshold values have been derived on the basis of the extensive literature compilation of VAN DEN BURG (1985, 1990). The present publication provides such values also for the tree species Douglas fir, red oak and black locust, which were introduced in Central Europe in the 18^th and 19^th century. For these species nutritional threshold values for the range of normal nutrition could be calculated for all main nutrients as well as for the most important trace elements according to the method described by GÖTTLEIN et al. (2011). However, for red oak and black locust in most cases the data situation did not allow to calculate the threshold between latent and real deficit. To estimate the quality of the values given in tables 1 to 3 they were classified on the basis of their relative standard error. For Douglas fir, in the literature already several classification systems exist which, however, at least partly, were not developed independently of each other. Comparing the VAN DEN BURG-derived thresholds of the Tab. 1 with the median of all literature systems, with the exception of the lower limits of N and K, there is a very good consistency (Fig. 1). According to GÖTTLEIN (2016) from the thresholds of the range of normal nutrition a range of harmonious nutrient element ratios, as well as a narrower range of optimal ratios can be calculated. These values were also derived and are given in Tab. 4.