The UMF-index: an indicator to compare silvicultural practices at the forest or forest estate level

Abstract

For more than two centuries forests in Europe have become increasingly shaped by a silviculture favouring pure, even-aged stands. Originally this was introduced to safeguard and restore wood production from remnants of a forest resource marked by heavy, unregulated exploitation. In response to developments in society, in particular regarding contemporary ideas on the sustainable use of natural resources, the current trend in forestry in Europe is towards a forest management based on natural processes. The silvicultural challenge is to create and maintain forest types that favour both production and environmental targets, i.e. yielding a high and valuable production, while simultaneously encouraging natural or close-to-natural biological processes. It is believed that such forest types, as a side effect, consider recreational, cultural and amenity values better than does ‘traditional’ plantation-oriented silviculture. In the temperate deciduous forest zone a more or less mixed broadleaved forest is considered the potential natural vegetation. Here, silviculture should move away from pure, even-aged stands managed under the clearcutting system with concentrated regeneration, restricted to a well-defined period and often occurring simultaneously over a relatively large area, towards a mixed, unevenaged forest with regeneration diffuse in space and time, occurring in minor forest gaps continuously throughout the rotation period. In terms of harvesting criteria this is a change from a stand level approach towards a single-tree philosophy. In time this development will lead to a forest that differs profoundly from the well known ‘normal forest’. As part of this undertaking, one of the challenges for forest research will be to deal with and synthesize findings from large-scale experiments and offer overall appraisals of management alternatives. In Denmark, such projects were initiated around 1995 (Skovsgaard et al., 1997). So, while accurate and detailed stand descriptions remain relevant, it is becoming increasingly important to characterize forest types and silvicultural practices at an aggregate level comprising a whole forest or forest estate. In this paper a simple indicator for this purpose is proposed and discussed.