Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco) in Europe: an overview of management practices

Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco), one of the most commercially important tree species in western North America and one of the most valuable timber trees worldwide, was introduced to Europe in 1827. It became a major species for afforestation in Western Europe after WWII, currently grows in 35 countries on over 0.83 million ha and is one of the most widespread non-native tree species across the continent. A lower sensitivity to drought makes Douglas-fir a potential alternative to the more drought-sensitive Norway spruce so its importance in Europe is expected to increase in the future. It is one of the fastest growing conifer species cultivated in Europe, with the largest reported dimensions of 2.3 m in diameter and 67.5 m in height. Pure stands have high productivity (up to 20 m3 ha-1a-1) and production (over 1000 m3 ha-1). The species is generally regenerated by planting (initial stocking density from less than 1000 seedlings ha-1 to more than 4000 ha-1), using seedlings of European provenance derived from seed orchards or certified seed stands. As the range of end-uses of its wood is very wide, the rotation period of Douglas-fir is highly variable and ranges between 40 and 120 years. When the production of large sized, knot-free timber is targeted, thinnings are always coupled with pruning up to 6 m. There is an increasing interest in growing Douglas-fir in mixtures and managing stands through close-to-nature silviculture, but the species’ intermediate shade tolerance means that it is best managed through group selection or shelter-wood systems

A review of black walnut (Juglans nigra L.) ecology and management in Europe

Black walnut (Juglans nigra L.) is a light-demanding, competition-intolerant, and tall forest tree species, introduced in Europe from North America at the beginning of the seventeenth century. It has an important economic role in Europe for producing wood and fruits, in agroforestry systems, as an ornamental tree for parks and avenues, for rehabilitation/restoration of degraded lands. The best sites for black walnut growth have warm and mild climates, with frequent and well-spread precipitation, and rich, deep, near neutral, well-drained and moist soils. Black walnut is a fast grower in youth and its height and diameter growth reach their peaks before age 30–35 years. It is globally the best known allelopathic species due to the juglone substance present in all parts of black walnut trees. The species is storm-resistant and not affected by any major pest or disease in Europe. It is regenerated by planting or direct seeding on bare land, in monocultures and mixed stands. The management of stands with black walnut, with a rotation period generally up to 80 years, include weeding (mandatory), cleaning-respacing (in dense stands), thinning (mostly from above), high and formative pruning (mandatory), with the aim of producing valuable wood for sliced veneer, solid furniture, flooring/parquet, cabinetry, panelling, sculpture, musical instruments, gunstocks

Provozní vápnění v Krkonoších =Large-scale practice liming in Krkonoše Mountains

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Biologická aktivita lesních půd na extrémně kamenitých holosečích =Biological activity of extreme skeletal forest soils on clearout

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Stav a vývoj půd v bilaterální Biosférické rezervaci Krkonoše/Karkonosze =Status and development of soils in the bilateral Biosphere Reserve Krkonoše/Karkonosze

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Půdy ochranných lesů Krkonoš =Soils of protective forests in the Krkonoše Mts

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Vývoj zdravotního stavu lesních porostů na výzkumných plochách v Krkonoších =Healthy status development of forest stands on permanent research plots in the Giant Mountains

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Akumulace biomasy a živin v jeřábových porostech na lokalitě Pomezní Boudy v Krkonoších =Biomass and nutrients accumulation in mountain ash stands located near Pomezní Boudy in Krkonoše Mts

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Substitution of Norway spruce for Douglas-fir: changes of soil microbial activities as climate change induced shift in species composition – a case study

Douglas-fir (Pseudotsuga menziesii [Mirb.] Franco) is the most common utilized introduced tree species in the tem-is the most common utilized introduced tree species in the temperate zone, planted in many European countries. Also, in the Czech Republic it represents the most planted exotic species as well. Its planted area exceeds 6,000 ha and represents 0.25% of the forest area of the country. In the last years, this species is supposed as convenient substitution for declining Norway spruce (Picea abies [L.] Karst.) stands under current climatic change (extreme drought, bark beetle outbreak). The changed species composition affects also soil dynamic processes, including litter decomposition and transformation. In the presented study, the respiration rate and nitrification intensity were compared in the stand parts dominated by Norway spruce and Douglas-fir in comparable site conditions (410 m a.s.l., 650 mm, 8 ºC, gleyic Luvisol, fresh oak-fir site with Oxalis acetosella, age 97 years). Analyses were performed in laboratory conditions by standard methods determining actual (basal) and potential respiration activity and intensity of ammonia and nitrate ion production. Admixture of Douglas-fir considerably intensified decomposition activities (soil respiration) and profoundly increased the nitrification rate in the surface humus and uppermost mineral soil layer – Ah horizon. Increased interest in the Douglas-fir silviculture needs increased care for forest soil dynamics with respect of nitrogen balance