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The primary aim of using treeshelters is offering protection for young trees against browsing and fraying. However treeshelters also significantly modify growth of protected trees. Even though there are many investigations on the behavior of broadleaved tree species in treeshelters, conifer species and particularly Douglas-fir [Pseudotsuga menziesii (MIRB.) FRANCO] have not been subject yet to comprehensive studies with different types of treeshelters. This is even more surprising as largescale damage caused by storms as well as devastations caused by climate change (and subsequent conversion) may most probably lead to further rising use of treeshelters and also more planting activities of Douglas-fir. Additionally silvicultural measures for compensating an expected short-coming of conifer timber from highly productive species on the roundwood marked together with an unbalanced situation of deer stock and natural regeneration may further intensify such trends. Thus, the aim of the study was to analyse growth and mortality of Douglas- fir in three different types of treeshelters including one control without protection considering two site categories of water supply (above-/below average paired sites), additional fencing (yes/no, for trees without treeshelter) and weeding/tending measures conducted every year (yes/no). The experimental design is distributed across 10 locations on public forest estates within southwest Germany/State of Baden-Württemberg. Monitoring took place over three vegetation periods (2012-2014) on three year old plants, planted bare-rooted. Growth of height (H) and stem diameter (at branch collar, WHD), measures of stability (H/WHD-ratio) as well as cumulative mortality have been recorded and compared across types of treeshelters and combined effects of water supply, fencing and mechanical weeding/tending using tests on mean values in mixed models. There were significant effects of the type of treeshelters on growth and mortality along the three years. Starting at the same size seedlings grown in sheltertype Ventex repectively Plantagard-shelter and Plantagard-mesh, when comparing to seedlings grown without protection, had a mean tree height higher by 27.4 cm respectively 18.2 cm and 13.7 cm (sign.), a mean WHD thinner by 1.5 mm, respectively 3.0 mm and 1.2 mm (partly sign.) and a higher mean H/WHD-ratio by 26 respectively 31 and 15 (sign.). The cumulative mortality was lower with a value of 12.7% respectively 15.8% and 18.1% in comparison to trees without protection (28.2%, sign.). Despite of several significant differences in height and diameter growth, measures of stability and mortality when compared to seedlings without protection, differences range still within values of trees grown up without protection as known from literature. Unprotected and planted Douglas-fir trees exhibit height development fast enough to overgrow shelters of a height of 90 cm after 2 years. Mean H/WHD-ratio of Douglas-fir three years after plantation represents sufficient stability, nevertheless it reaches published values from trees under long-term experiments of canopy closure. When analysing effects of treatments jointly with specific combinations of water supply, fencing and mechanical weeding/tending only rarely large differences in growth and mortality were found compared to seedlings grown in different sheltertypes. Additionally, when considering full costs of tree shelters as well as the potential to improve local game management, we do not recommend the use of tree shelters in the case of Douglas-fir. [ABSTRACT FROM AUTHOR]

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 18th and 19th 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. [ABSTRACT FROM AUTHOR]

The article reports that "Königseiche Kammerwald", a 370-year-old sessile oak in the Rhineland-Palatinate state forest was awarded the 17th national heritage tree at the end of June with several meters above the neighboring trees, strong Douglas firs, beeches and oaks.