Ekoparkernas inverkan på långhornskalbaggar (Cerambycidae) : artrikedom, abundans och artsamhällen i jämförelse med kommersiellt brukad skogsmark

Sammanfattning: Several dead wood-dependent beetles need substrates which to great extent have been disfavored by intense forestry. Active and continuous restoration in Ecoparks may offer an option with intention to improve the habitation conditions. This study investigated, with data from 2011 and 2020, if longhorn beetle species communities, abundance, species richness and red-listed occurrence were different in an Ecopark compared to a conventional production landscape as a reference. The hypothesis was that the species richness and abundance in general are higher in the Ecopark, and that the trend over time will indicate a sharper difference between Ecoparks and conventionally managed forest. Regarding species communities and red-listed species, the assumption was that the Ecopark over time will inhabit another species composition and more redlisted species compared to the conventionally managed forest. The assumptions are based on earlier studies showing that dead wood-dependent beetles are favored by nature conservation – in particular by creation of dead wood. The beetles were collected in 2011 and 2020 by using insect traps on high stumps from birch and pine - in both Ecopark Hornsö and its reference landscape Hälleskog. Differences between Ecopark and reference landscape regarding abundance and species richness were tested with GLM-models. Differences in occurrence of red listed species over time in the Ecopark were also tested with GLM-model. Venn diagrams and box plots were used to illustrate data. The tests showed a generally higher species richness and abundance of longhorn beetles in the Ecopark compared to the reference area, independent of the year. The models also showed a general decline of abundance and species richness from 2011 to 2020, independent of the year. Red-listed longhorn species occurrence in the Ecopark showed a decline from 2011 to 2020. The landscapes inhabited on both occasions over 50 % of the species in common. The Ecopark inhabited on both occasions more than 30 % of the species not found in the production landscape. The production landscape on both occasions inhabited 10 % of the species not found in the Ecopark. A total of 6 red-listed species was only found in the Ecopark, and not in the production landscape. The number of red-listed species found in the production landscape was 3, but these species were also found in the Ecopark. The results indicate that the strengthened conservation creates a more favourable envirionment for longhorn beetles compared to conventional forest land. Despite that the study in contrast to the hypothesis do not show increased abundance or species richness over time, there are however indications that the Ecopark has a value – in particular regarding the 6 red-listed species in total found exclusively in the Ecopark, but not in the conventional production landscape.