Metod för inventering av underhållsbehov för skogsdiken
Large areas have been ditched in Sweden during the past 100 years to improve the forest production. Ditching and also maintenance of old ditches are operations having mainly negative effects on water quality, flora and fauna and changing characteristics of soil. The purpose of this study was to suggest a method for inventory of the need for ditching maintenance in old forest ditches that takes biodiversity, water protection and forest production into consideration. Inventory methods from five Swedish and Finnish forest companies, agencies and organisations were compared. Their employees were interviewed about their handling with ditches, forest production and nature conservation. The results show that there are four major questions that have to be answered in order to decide whether old ditches should be left as they are, maintained or if there are other operations that could be needed. First, it is important to know whether the original ditches has had an improving effect on forest production and second, what effect a cleaning of the ditch would have on the growth at present. The third and fourth theme that has to be valued is what the effects could be on biodiversity and the environment and all this has to be weighted together. Maintenance of old ditches is a complex subject. It is of major concern to have a comprehensive view and to look outside the specific object for eventual causes and effects. A method for inventory of need for ditching maintenance is a good tool in the planning.