Habitat trees in managed forest: how many are available and to what cost can they be maintained?
2010
Niedermann-Meier, S., Ecolinnea GmbH, Adliswil (Switzerland) | Mordini, M. | Bütler, R. | Rotach, P.
Habitat trees are important elements to maintain forest biodiversity. An effective way to provide habitats for species depending on old growth structures may be the conservation of a certain number of habitat trees integrated in managed forests. It has been suggested to maintain at least five such habitat trees per hectare for this purpose. In order to evaluate the number of existing potential trees as well as the financial consequences for the forest owner, we sampled all trees greater than 40 centimetres at breast height on sample plots of the forest inventory in the forest of Baden, Switzerland. Based on a catalogue of important traits of old trees which are important for the survival of five groups of organisms (insects, birds, bats, lichen, fungi), we assessed the ecological value of all trees. We also estimated their economic value in terms of net wood value for each tree. Results show that the conservation of five currently existing habitat trees per hectare would cause significant financial losses for the owner, amounting to 850 Swiss francs per hectare or 170 francs per tree in our example. Moreover, ecological values of many of these trees would be rather low because there are not enough suitable trees to select from. Ecologically valuable trees most likely were removed during tending of stands. Instead of general demands like for example five trees per hectare it seems more effective to concentrate on the currently existing ecologically valuable trees only. Financial losses may need to be covered by public funding in cases where they are high. Moreover, management of habitat trees needs to be planned on a long-term basis. Conservation and promotion of a certain number of habitat trees need to be integrated in tending concepts from early developmental stages.
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