Transformation to irregular structure of an upland conifer forest

The Glentress Trial was established by M.L. Anderson in 1952 as a demonstra tion of transformation to irregular structure of an upland conifer forest i n southern Scotland. The trial area (117 ha) is one of the longest continuo usly-studied forest research areas in Britain. The dominant tree species ar e Sitka spruce, European larch, Scots pine and Douglas-fir. The most import ant silvicultural system is group selection, with group size varying from 0 .1 to 0.2 ha. Groups are restocked by planting or natural regeneration. int erim results point to the development of an irregular forest structure, alt hough the transformation will not be complete until 2033. The trial demonst rates the value of continuous cover forests in meeting multiple forest mana gement objectives, and is a resource of increasing importance for silvicult ure education and long-term research.