Transformation to irregular structure of an upland conifer forest

The Glentress Trial was established by M.L. Anderson in 1952 as a demonstration of transformation to irregular structure of an upland conifer forest in southern Scotland. The trial area (117 ha) is one of the longest continuously-studied forest research areas in Britain. The dominant tree species are Sitka spruce, European larch, Scots pine and Douglas-fir. The most important silvicultural system is group selection, with group size varying from 0.1 to 0.2 ha. Groups are restocked by planting or natural regeneration. Interim results point to the development of an irregular forest structure, although the transformation will not be complete until 2033. The trial demonstrates the value of continuous cover forests in meeting multiple forest management objectives, and is a resource of increasing importance for silviculture education and long-term research. Key words: transformation, irregular structure, uneven-aged management, Sitka spruce, Douglas-fir, long-term silviculture research