Nordwestdeutsche Forstliche Versuchsanstalt

Göttingen, Germany

Nordwestdeutsche Forstliche Versuchsanstalt

Göttingen, Germany
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The present evaluation focuses on a benchmarking of selected Douglas-fir (Pseudotsuga menziesii [Mirb.] Franco) provenances up to the age of fifty-eight years, drawing upon empirical data from six northeast and northwest German individual trials within the International Douglas-fir Provenance Test Series of 1961 with a wide site-climatic range. The investigated feature is mean height of predominants (H100). Furthermore, the development of the assessed provenances is characterized by total volume production (cubic metres solid volume per hectare). With the aid of a wide data base, phenotypical source differences are elaborated on the basis of the number of straight stemmed future crop trees. The following questions are asked: (1) How do the provenances differ in relation to top height and is it possible to observe a variation of provenance-specific increase in height during the previous twenty years? (2) What are the differences between the provenances regarding total volume production and can a yield-level divergence be diagnosed among the trial plot locations? (3) Which origins recommend themselves for their stem quality? Twenty-five North American provenances and one German stand, Kiekindemark, grown from North American seeds, were evaluated. The results regarding provenance dependent height increment are at least singly significant. The provenance-specific differences in quality are also statistically assured. Based on standardized top height values, Humptulips on the Olympic- peninsula in the northwest of the federal state of Washington is the most effective of all the provenances. The Canadian ecotypes from the coastal 'fog-belt' as well as from the southern interior 'wet-belt' show less than average performance, just like the sources from Oregon and Washington that lie higher than 600 metres above sea-level. Over the last twenty years the tested origins have shown little ranking order variation relating to top height increase. Of all the sites. Mineral, Silver Lake and Humptulips have the greatest amount of total volume increment. In the evaluation mean however, the Canadian stand strains show the weakest growth. There are clear differences in the yield-levels of the trial sites. Gold Hill, Mineral and Ashford have the best stem quality, the Salmon Arm provenances Larch Hill and Mt. Ida range at the bottom of the scale. The domestic ecotype Kiekindemark has a positive yield performance, which, however, can only be ascertained for the growth site Parchim 6223a. Furthermore, the restricted amount of random samples, only obtained from one measurement plot, does not permit comparison with stem shapes of the remaining sources. The significance of well-proven origins and the problem of Douglas-fir seed supply in the light of existing national and European rules and regulations are also considered.

Hanewinkel M.,Albert Ludwigs University of Freiburg | Albrecht A.,Forstliche Versuchs und Forschungsanstalt Baden Wurttemberg | Schmidt M.,Nordwestdeutsche Forstliche Versuchsanstalt
Schweizerische Zeitschrift fur Forstwesen | Year: 2015

The paper deals with different influencing factors that determine storm damage to forests and the question how this damage can be minimized. The influence factors include treerelated parameters like species, tree height and h/d-relation, terrain-related parameters (encompassing wind speed and soil condition), and type of forest management as well as stand structure. The analysis of a multitude of studies including empirical as well as mechanistic models reveals that coniferous species, especially Norway spruce, show a higher vulnerability towards storm damage than broadleaves. Many investigations point at a significant influence of tree height on storm damage probability, while the h/d-value does not have the same importance. Besides that, the influence of management operations, stand structure and surrounding forest stands as well as the vulnerability of selection forests ("plenter forest") are analysed. Silvicultural treatment, mostly timing and intensity of the interventions, plays a role for determining damage severity, as well as soil water content (waterlogged soils) and exposure towards the main wind direction. Plenter forests appeared not to be very vulnerable to storm damage in the existing investigations in Switzerland, however, due to the lack of sufficient data, a general superiority of these uneven-aged forests compared to even-aged ones cannot be proved at the moment. Based on a discussion on the importance of the different parameters, measures to reduce storm damage to forests are discussed. Hereby mainly the choice of tree species, the limitation of the dominant height of forest stands as well as early and intensive thinning are investigated.

Meyer P.,Nordwestdeutsche Forstliche Versuchsanstalt | Molder A.,Nordwestdeutsche Forstliche Versuchsanstalt
Forstarchiv | Year: 2017

Improved understanding of natural tree mortality is urgently needed. We analyzed beech (Fagus sylvatica) and oak (Quercus petraea, Q. robur) mortality in unmanaged forest stands by using long-term inventory data from strict forest reserves in Lower Saxony (Germany). We asked whether the mortality of these two tree species can be explained by competition, and whether beech and oak forest communities differ in respect of the relevance of causal factors of tree death. Competition was a significant factor regarding both beech and beech forest communities. However, death of oaks in oak forest communities could not be explained by competition. We hypothesize that in oak forest communities competition is masked by oak decline.

The proof of the autnenticity of seed lots is Dasic for tne privately organized certification and is used in the control case, the discovery of violations of the Act on forest reproductive material (Forstvermehrungsgutgesetz, FoVG) in Germany. A method is presented that allows to compare seed-lots according to their largely tamper-proof signatures of stable isotopes and content of the elements C, N, H, 0. This comparison allows an examination of individual cases with the help of a multivariate discriminant analysis. By crossvalidation in 79 out of 110 (72%) comparisons made it was possible to completely differentiate the samples from nine German seed stands and two imported seed lots from North America. In addition, for a test data set comprising of stable isotope signatures from another German and a North American seed lot, their non-affiliation could be confirmed. Significant differences between seed lots of different stable isotope delta-values became obvious. © DLV GmbH.

Hornbeam (Carpinus betulus L) in central europe is a middle sized tree, commonly growing in mixed stands with oak. Information of genetic variability of hornbeam is very rare. Within its distribution area well growing stands are known with high grade timber, meanwhile especially in the western part of the geographical extension area hornbeam is characterized by poor timber quality. In 1984 the Forest Research Institute of Lower Saxony has established field trials with hornbeam provenances to find the best suitable provenances for cultivation in this region. Results from two test plots are presented.The trial includes provenances from Germany, Poland, Croatia, France and Austria. Data collection covered height, diameter and timber quality attributes. Diameter and height can be compared with existing yield tables, but there is much variety in quality. Up to now recommendations for specific provenances based on the trial results cannot be given.

Grotehusmann H.,Nordwestdeutsche Forstliche Versuchsanstalt
Landbauforschung Volkenrode | Year: 2014

25 years old Scots pine progenies descending from 19 seed orchards and four stands are tested on three sites in the North German Plain. Plus trees from the lowland are inferior in quality and yield compared to those originating from north-western Poland (formerly "East Prussia") and from the Black Forest and Bavarian Forest. Seed orchards with plus trees originating from north-western Poland generate progenies with a well-balanced proportion between high quality and good yield performance.

Nagel J.,Nordwestdeutsche Forstliche Versuchsanstalt | Spellmann H.,Nordwestdeutsche Forstliche Versuchsanstalt | Pretzsch H.,TU Munich
Allgemeine Forst- und Jagdzeitung | Year: 2012

The tradition of long term forest experiments started in 1873 with a manual for thinning experiments published by the Society of German Forest Research. Many of these experiments are still in observation and have been used to understand the principles of forest growth, to test hypothesis, to derive models for sustainable management and to give advice to forest managers. Since the 1970s many permanent forest inventories have been established to describe the forest on a national, regional or company level. The availability of growth information from inventory data puts the amount of the long term experiments into question. The main difference between both sources of information is that long term experiments are designed to study cause and effects by active variation of one variable. Inventories are made to estimate unbiased the state or the change of a variable of interest, in example the standing volume or the volume growth. Inventory data represents usually average conditions and rarely extreme conditions which are important for understanding and modelling. However long term experiments are expensive in time and effort. Therefore, it is often not possible to establish the experiments on wide amplitude of site conditions. The use of existing inventory data in combination with long term experiment is a possibility to enlarge the data base and derive fast results for current issues. For example Albert and Schmidt (2010) used this approach to model climatic effects on the site index of Norway spruce and European beech. Long term experiments will still be essential for forest research. Available inventory data can be useful to fill in data gaps and to project the long term experiment results to a regional or overall site level.

Hauck M.,University of Gottingen | Zimmermann J.,University of Gottingen | Jacob M.,University of Gottingen | Dulamsuren C.,University of Gottingen | And 3 more authors.
Environmental Pollution | Year: 2012

Tree-ring width of Picea abies was studied along an altitudinal gradient in the Harz Mountains, Germany, in an area heavily affected by SO 2-related forest decline in the second half of the 20th century. Spruce trees of exposed high-elevation forests had earlier been shown to have reduced radial growth at high atmospheric SO 2 levels. After the recent reduction of the SO 2 load due to clean air acts, we tested the hypothesis that stem growth recovered rapidly from the SO 2 impact. Our results from two formerly damaged high-elevation spruce stands support this hypothesis suggesting that the former SO 2-related spruce decline was primarily due to foliar damage and not to soil acidification, as the deacidification of the (still acidic) soil would cause a slow growth response. Increasing temperatures and deposited N accumulated in the topsoil are likely additional growth-promoting factors of spruce at high elevations after the shortfall of SO 2 pollution. © 2012 Elsevier Ltd. All rights reserved.

The comparison of various thinning regimes for beech (Fagus sylvatica L.) is focused on empirical as well as simulated radial and diameter increment of selected trees. The following questions are dealt with: (1) What effects do several stand tending measures have on radial increment within the framework of young stand thinning during a stand development phase with the highest increment capacity? (2) What is the effect of a modelled image of thinning variants on the attainment of a target diameter of 60 cm or rather on the age related risk of beech heart? (3) In how far is it possible to make model-based predictions of beech trunk increment on highly productive sites in northwestern Germany as a result of the applied thinning regimes? The possibility of duramenisation of beech is dependent on trunk diameter and age respectively and leads to a decline in timber value. From a diameter of 60 cm upwards, respectively beyond an age limit of 120 years, there is an increased probability of a negative effect on timber grading. The present assessment is based on 3 thinning experiments carried out between 2002 and 2005 on good to very good sites in low mountain ranges of northwestern Germany. The defined thinning experiments encompass 2 groups regarding basic forest management procedure. Accretion thinning according to the principles of the forest management strategy 'Qualify - Dimension' (abbr. QD-strategy) and future crop tree oriented selective thinning concentrate exclusively on the growth and furtherance of selected trees (z-stems), while crown thinning with designated future crop trees also entails treatment of the intermediate spaces. The QD-strategy moreover is based on a limited amount of future crop trees per unit area. The influence of the various regimes on radial increment of the selected trees at breast height (1.3 m) is assessed using empirical time series data: accretion thinning leads to higher radial increment after two applications. The simulation of the diameter development of the individual trees based upon the TreeGrOSS-library (Tree Growth Open Source Software; Nagel 2009). The simulations comprise periods up to 90 years. The slope of diameter development lines (DBH) becomes shallower with increasing tree age, even with intensive accretion thinning. Thus, asked increment will only occur, if thinning measure is carried out from an early stage. Only on capable sites in northwestern Germany (absolute stand top height site class at the age of 100 years ≥ 39 m) will nearly all future crop trees up to an age of approximately 130 years attain the target diameter of 60 cm, with an accordingly lower size-related beech heart devaluation risk. The DBH-achievements of beech suggested by the QD-concept of 80 cm-plus for periods ranging from 110 to 120 years are not projected by the growth model, even on highly productive sites in northwestern Germany. © DLV GmbH.

Meyer P.,Nordwestdeutsche Forstliche Versuchsanstalt | Schmidt M.,Nordwestdeutsche Forstliche Versuchsanstalt
Forest Ecology and Management | Year: 2011

Currently, there is much debate about what strategy is most suitable for increasing old-growth attributes in forests that have been managed intensively for wood production in the past. Passive restoration, i.e. cessation of forestry interventions, should be considered when the old-growth attributes desired can be restored within a feasible period of time. Our study focuses on standing and lying coarse dead wood (≥20cm diameter) in beech-dominated forests in northwestern Germany. We analyzed monitoring data of 545 sample plots (sized 500-1000m 2) from 12 strict forest reserves (SFRs). The SFRs had been without forestry intervention for up to 28 years.Both, number of dead objects and volume of dead wood (m 3ha -1) increased significantly with ongoing time since abandonment from forestry interventions. The mean amount doubled from 9 to 18m 3ha -1 within 10 years. The proportion of standing dead wood was about 40% of the total dead wood pool ≥20cm diameter. With mixed linear modeling we showed that dead wood increased by a mean net rate of about 1m 3ha -1a -1. Therefore, after three decades critical values for restoring the dead wood pool could be reached. We hypothesized that the rate of dead wood input is mainly determined by disturbance driven tree mortality such as oak decline, bark beetle infestations and storms.A comparison with primeval forests or reserves abandoned more than 100 years ago showed that the SFRs studied are at the beginning of a long process of dead wood accumulation. Based on our results, the abandonment of forest activities in harvestable pure and mixed beech stands is an effective strategy for restoring the dead wood pool. © 2010.

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