A mountain pine beetle outbreak in the mid-1970s in the southern interior of B.C. resulted in relatively widespread salvage logging of lodgepole pine from mixed pine, Douglas fir stands and mixed pine, western larch stands. In pine-leading stands, fir or larch are left as residual standing trees. These "seed trees" provide a source of fir regeneration to provide a secondary species to lodgepole pine, which regenerates naturally from abundant cone slash. This is a relatively widespread practice that has been in place since the early to mid-1970's when lodgepole pine became an important commercial timber species. Thus, this form of green-tree retention is not a new management approach to salvage or conventional timber harvesting in this region. Because of this relatively long history, it is possible to do a retrospective investigation of the influence of harvesting lodgepole pine on stand structure and biodiversity 30 years after cutting. Stands with residual green trees, composed of dispersed to aggregated Douglas fir with understory lodgepole pine, cover several landscapes in the southern interior, having arisen from harvesting over the past 30 years. Thus, a major question is: how do these stands compare to those uncut in terms of stand structure and development of late seral forest conditions? This question has direct relevance to sustainable forest management for wildlife habitat and biodiversity. Stand structure and the responses of several mammal groups are being used as indicators of sustainability and biodiversity. Examples of these species and groups are the masked shrew (Sorex cinereus) and the southern red-backed vole (Clethrionomys gapperi) on the forest-floor and the northern flying squirrel (Glaucomys sabrinus) in the arboreal mammals, and mule deer (Odocoileus hemionus) in the large mammals. Large herbivorous mammals such as mule deer may be affected by variable retention harvests because habitat use by this species is particularly important during winter periods. This is an ongoing issue with respect to winter range conditions in and near harvested units in forests of the southern interior of B.C.
Thomas P. Sullivan.
Sullivan, Thomas P.. 2007. Stand structure and maintenance of biodiversity in green-tree retention stands at 30 years after harvest: a vision into the future. Forest Investment Account (FIA) - Land Base Investment Program. Forest Investment Account Report