Enhancing biodiversity on industrial land

Abstract

The significant decline in flower-visiting invertebrate populations across Europe has been largely attributed to habitat loss and agricultural intensification. To facilitate and enhance population growth, reversal of biodiversity loss within the local landscapes should be addressed. This study identifies and assesses habitat features associated with flower-visiting invertebrates with the aim to develop management targets to enhance biodiversity. The abundance and diversity of flower-visiting invertebrates were compared between six habitat areas within the grounds of the Alcan Aluminium smelter. The majority of invertebrates were attracted to high flower density, rather than a particular habitat area. Underpinning the project, this study identified three priority habitats utilised by invertebrates; Grassland, Woodland, and Hedgerows. Within grassland, the impact of mowing regimes on flower-visiting invertebrates and flowering plants was assessed. A reduction in mowing frequency resulted in a significant increase of both flower density and diversity within the sward. Comparisons to local flower-rich grasslands showed that following appropriate management the grassland at the Alcan smelter was comparable, if not better in some cases in terms of flower density, along with increasing stability of the plant and invertebrate network. Steps to establish a diverse understorey within the woodland began with an assessment of the seedbank. Results closely mimicked the above ground flora, confirming a low abundance and diversity of flowering species. Germination trials followed to determine the suitability of current light levels to support woodland flowering plants; findings indicated the need for canopy management to enhance the woodland. Hedgerows are an important landscape feature for invertebrates, this study showed that species-rich hedgerows hosted a greater diversity of invertebrates than species poor hedgerows. Indicating the importance of hedgerow management, and the potential benefits of gap filling with native shrub species. Finally, the presence of suitable nesting habitat is another important consideration when managing habitats for invertebrates. Here we assessed the use of three different substrates for suitability in building artificial nests (aimed primarily at bees and wasps). The uptake of these nests increased with exposure length, suggesting that artificial nests do indeed support breeding invertebrates, and could be successfully used as a tool for invertebrate conservation in the future.