Building resilient wooded landscapes: How can we support saproxylic invertebrates into the future?

Decaying wood hosts a diverse network of saproxylic invertebrates. These play important roles in forest functioning, including pest control, pollination, and nutrient cycling. However, declines in ancient and veteran trees in UK landscapes threaten saproxylic communities. The present research sought to address this through investigating multiple aspects of saproxylic habitat use and creation.
Previous studies of saproxylic invertebrate landscape use have identified scales at which habitat density is most important. However, many of these studies were done in dense woodlands and none have been attempted in the UK. This research sought to fill these knowledge gaps by investigating habitat density scales of importance to invertebrate populations in English open-grown oak landscapes. Flight interception trapping data showed that higher veteran tree densities over a 250 m radius positively correlated with saproxylic community diversity, whilst higher densities over smaller scales support rare species.

The second aspect of this research explored beetle boxes as a deadwood habitat creation method. The present research built upon previous studies by investigating a novel ground-level design to replicate basal tree hollows. It also tested the potential of different construction materials and content variations in improving beetle box function. Results showed that plastic beetle boxes contained similar abundances and diversities of deadwood-associated beetles than those made of wood. However, the wood mould in plastic boxes became significantly drier than that in wooden boxes. The addition of poultry faeces to beetle boxes as a source of nitrogen was associated with higher abundances and diversities of some beetle groups. No evidence of the basal hollow specialist, Limoniscus violaceus, was found in beetle boxes; however, more long-term monitoring is needed to thoroughly investigate this. This research also noted the potential for beetle boxes to function as a public engagement tool to promote a widespread appreciation of the importance of deadwood ecosystems.