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Where trees need to be killed to improve the health, diversity or productivity of the remaining stand, the usual practice is to harvest them. However, if conventional harvesting and timber extraction is impractical or not economic, ‘felling to recycle’ (also referred to in the past as ‘felling to waste’ or ‘thinning to waste’), where the cut timber is left on site to degrade, is sometimes necessary. Our research investigated whether chemical thinning, which involves the killing of standing trees through the application of herbicides, might provide a more cost effective alternative to either manual ring barking or felling to recycle.We found that applying glyphosate in an encapsulated form as Ecoplug Max® at a rate of 0.068 g a.i. glyphosate per cm of stem diameter killed ~90 per cent of 47-year-old standing Douglas fir within two full growing seasons of treatment. Ecoplugs appeared to be a more effective method of applying glyphosate to kill standing trees than the traditional method of chemical thinning which involves spraying liquid glyphosate into cuts made in the tree stem. Both traditional chemical thinning and non-chemical ring barking were also moderately effective in our work, but the speed of kill was slower and overall efficacy lower than when using Ecoplugs. Ecoplugs may also have other advantages such as eliminating the risk of chemical drift and operator contamination, and providing the potential for year round application, but they are 300 per cent more expensive to use than traditional chemical thinning and 30 per cent more expensive than manual ring barking. [ABSTRACT FROM AUTHOR]

The aim of this study was to examine the species composition and structure of woodlands that have been managed using the Bradford-Hutt system for 54 years on the Tavistock Estate, Devon in England. The Bradford-Hutt system is a unique method of transforming even-aged stands to continuous cover management because it is not inspired by traditional silvicultural systems such as shelterwood or selection. Instead the system takes the main elements of clearfelling, i.e. planting, thinning and felling, and organizes them on a small-scale, grid pattern in such a way that there will be continuous canopy cover and good access for forest operations. The system has been successful in creating mixed species stands with an uneven-aged structure that meet present policy requirements for resilience but, to our knowledge, it was not applied elsewhere. Options for future management include continued use of the Bradford-Hutt system; however, now that the structure has been created and natural regeneration is apparent, this may not be the best method and other options are examined. The system was developed by the sixth Earl of Bradford and his forester Phil Hutt, both of whom deserve credit for their pioneering efforts and challenging the 'forestry establishment' to examine alternatives to clearfelling some 30-40 years before continuous cover became part of mainstream forest management in Britain. [ABSTRACT FROM AUTHOR]

Pacific silver fir ( Abies amabilis Douglas ex J. Forbes) was first introduced to Britain in 1830 but has not been widely planted and occupies a minute part of the forest estate. The results of six experiments established in the uplands of Britain examining material from 30 collection sites in 14 seed zones clearly demonstrate that its potential has not been recognised. The trials were assessed after 28 years and show that Pacific silver fir has the potential to be as productive as other common species options. There was little variation in performance between the 14 seed zones, and future seed collections could be carried out within a wide geographical range, including mainland British Columbia and Vancouver Island and the Olympic Mountains and western Cascades of Washington. The silvicultural characteristics of the species mean that it could be used more widely to diversify forests in Britain both as a plantation species and in the wider use of continuous cover management. More work is justified to determine its susceptibility to Annosum root rot ( Heterobasidion annosum (Fr.) Bref), confirm its productivity on sites with rainfall below 800 mm·a-1 and (or) with a high peat content, and provide more detail on its wood properties. [ABSTRACT FROM AUTHOR]

Stands of Sitka spruce ( Picea sitchensis (Bong.) Carr.) originating from natural regeneration can be extremely dense with high mortality, poor growth form and low volume production. Although costly, respacing (pre-commercial thinning) can reduce resource competition for the remaining trees, altering the final crop produced. Three experiments were established to examine the effect of respacing 1-2 m tall trees to different target densities. The impact on stand growth and yield was measured 11-17 years after respacing, and the longer-term impact was modelled to year 50. Unrespaced control treatments self-thinned at a similar and constant rate at two sites. At the third, extremely high initial density resulted in a higher rate of self-thinning and lower density after 11 years. Wider respacing treatments resulted in larger mean tree diameter, but there was no significant effect of respacing on stand volume 11-17 years after respacing; greater diameter growth did not compensate for low tree number. Results indicate a volume penalty associated with delaying respacing until trees were 4 m tall, but this treatment was unreplicated. Modelled stand volume in year 50 was higher for the 2.6 m × 2.6 m respacing treatment than for the 1.8 m × 1.8 m, 2.1 m × 2.1 m or 3.3 m × 3.3 m treatments. However, open-grown conditions may reduce timber quality compared to closer spacing treatments. The results are presented using a stand density management diagram for Sitka spruce growing in Canada and support recent suggestions that British stands have a shallower size-density relationship than Canadian stands. [ABSTRACT FROM AUTHOR]