Management and creation of Open Mosaic Habitat for invertebrate conservation

Some brownfield sites can support comparable invertebrate diversity to semi- natural early successional habitats. This was recognised in the designation of Open Mosaic Habitat on Previously Developed Land as a UK conservation priority. This project developed in response to the need for information to assist with management of brownfields protected for nature conservation, and from the lack of evidence about effectiveness of brownfield mosaic habitat creation. The study included: management interventions at Canvey Wick in Essex, a brownfield nature reserve; mosaic habitat creation by substrate addition in unmanaged grassland; and placement of artificial aculeate nests on green roofs in London.
Scrub clearance at Canvey Wick produced distinct communities of stenotopic invertebrates immediately after management, and one year later. Trait-based analysis showed that staphylinids and spiders were larger at undisturbed plots, dispersal traits for carabids and spiders were linked to disturbance, and trophic shifts for all three groups. In species-poor grassland at Canvey Wick, stenotopic beetles particularly benefitted from scraping, whereas stenotopic and generalist spiders were more abundant after excavator disturbance, and at unmanaged plots. Carabids and staphylinids were larger at undisturbed plots, although treatment responses in leg and eye morphology were not shared.

Substrate addition in unmanaged grassland on clayish soils in south Essex benefitted nesting aculeate Hymenoptera, particularly in the first year. Stenotopic early successional beetles and spiders were more abundant in the second year, although species composition was similar to the grassland. Cavity nesting aculeate Hymenoptera were reared from biodiverse and unvegetated roofs in London, although most sites were not colonised, and substrate nests were unsuccessful.

Results were examined in relation to broader literature concerning invertebrate conservation in early successional habitats. Implications for land managers were discussed, including species turnover, habitat structure, and potential benefit to ecological networks from habitat restoration, management and creation in appropriate locations.