Ecological restoration of natural disturbances in boreal forests

摘要

Worldwide declines in biodiversity have accentuated the need for conservation actions. Unfortunately, the decline is unlikely to be reversed by traditional conservation alone. Instead the practice of ecological restoration has come to play an ever increasing role. It is therefore important to develop methods that are beneficial for biodiversity, cost efficient and applicable on larger scales. By using a before-after control-impact experiment in boreal forest voluntary set-asides, I evaluated the response of forest-dwelling beetles and flat bugs to two cost neutral ecological restoration methods. The two restoration treatments, restoration burning and artificial gap creation were aimed at emulating natural disturbance processes, at the same time as they were expected to improve conditions for biodiversity. I compared the results from the two treatments with that of unmanaged reference stands.ududI found that beetles showed strongest response to restoration burning by increasing in abundance and species richness directly, as well as one year after restoration. In addition the composition of species communities differed significantly between beetles collected in burned stands compared to those collected in gap-cut and reference stands immediately after restoration. One year after restoration the composition of species communities differed significantly between all three treatment groups. Flat bugs also responded strongest to restoration burning by displaying higher abundance and species richness in burned stands compared to gap-cut- and reference stands. I also found that dead wood substrate type mattered for beetles. Tree species and tree posture, i.e. if the trees were standing up or lying down, had the strongest effect on the composition of species communities emerging from the dead wood. In addition, tree species was of importance for abundance and species richness in gap-cut stands, where spruce trees generally had higher counts that birch- and pine trees.ududAs the voluntary set-asides already were established and the restoration costs were fully covered by revenues from the extracted timber, the restoration methods applied in this study may prove particularly useful. Not only because of the positive effects on forest biodiversity, but also due to their high level of applicability and cost effectiveness