Testing the potential of a bush-cricket as an indicator for structure- and species-rich forests

Central European forestry is currently facing a challenging situation, striving against climate change impacts. Forest restoration is crucial but monitoring the impact of forest management on biodiversity is needed to incorporate this factor into management decisions. In open-land habitats, Orthoptera are well-known indicators of land use intensity, succession states, and biodiversity. We therefore hypothesized that forest-dwelling Orthoptera may also serve as indicators in temperate forests. We studied the habitat requirements of the common saw bush-cricket, Barbitistes serricauda. As Orthopterans typically depend upon a specific vegetation structure, we assessed canopy structure via hemispherical photography, as well as understory structure and plant diversity via Braun-Blanquet analysis on forest plots with and without the species' presence. We conducted the study in several forest types. Forest type did not have an overall effect on its presence, but it was less frequent in alluvial forests. When analyzing habitat parameters in detail, the occurrence of the species was significantly associated with canopy openness, light radiation, vertical vegetation structure and herbaceous plant diversity. We calculated its indicator value for these variables, resulting in a significant indication potential for vertical connectivity and gaps in canopy openness. As these parameters have been shown to benefit many other arthropod species, we conclude that Barbitistes serricauda is a suitable indicator for well-structured forest habitats that can promote diversity. Due to its lack of specialization on certain tree species, it may be used in various forest types and under different management strategies.