Biodiversity and ecosystem services in forest - the ‘BioHolz’ project

Abstract

Whenever a tree dies, it makes room for millions of organisms contributing to the crucial ecosystem process of decomposition. The diversity of saproxylic organisms, which are depending in at least some stage of their life on decaying wood, comprises about one third of all forest species. Forest management in Europe of the last centuries changed forest structures and in particular reduced the amount of available dead wood, which is mirrored by the current extinction risk of saproxylic species1. However, society expects a forest to be a multi-functional ecosystem, which provides, among others, timber, recreation and biodiversity conservation. In the trans-disciplinary project ‘BioHolz’, we try to develop management approaches combining ecological, economical and social science perspectives. One challenge is to integrate restoration of saproxylic diversity in managed forests in the economically most efficient way. We established several field experiments, which investigate biodiversity, economic costs and public perception associated to dead wood. The balance between ecological and economic demands is mostly a question of how much dead wood is needed for effective conservation. However, in two experiments it could be shown that for saproxylic diversity dead wood heterogeneity is more important than just dead wood amount. In one of these experiments the importance of dead wood in the forest canopy was highlighted2. In addition to a reduction in economic gain through deadwood increase, bark beetles colonising Norway spruce pose a potential threat to the remaining stand, with the consequence that conservation of other saproxylic beetles plays a minor role in bark beetle management. Within two experiments, a new technic of on-site bark scratching was developed facilitating the opportunity to reduce bark beetle populations while promoting saproxylic diversity3. Furthermore, public perception towards bark scratching was more favourable than formerly applied full debarking strategies. In a further experiment within the ‘BioHolz’ project, we investigate ecological, economic and social aspects of standing and lying logs in different spatial arrangements and under different microclimatic situations at the forest stand level.

1.Seibold, S., Brandl, R., Buse, J., Hothorn, T., Schidl, J., Thorn, S. & Müller, J. (2015) Association of extinction risk of saproxylic beetles with ecological degradation of forests in Europe. Conservation Biology, 29, 382–390. 2.Seibold, S., Hagge, J., Müller, J., Gruppe, A., Brandl, R., Bässler, C. & Thorn, S. (2018) Experiments with dead wood reveal the importance of dead branches in the canopy for saproxylic beetle conservation. Forest Ecology and Management, 409, 564–570. 3.Thorn, S., Bässler, C., Bußler, H., Lindenmayer, D.B., Schmidt, S., Seibold, S., Wende, B. & Müller, J. (2016) Bark-scratching of storm-felled trees preserves biodiversity at lower economic costs compared to debarking. Forest Ecology and Management, 364, 10–16.