The role of dietary breadth in national bumblebee (Bombus) declines: Simple correlation?

Bumblebee species declines have been reported in Europe, North America and Asia. Loss of suitable habitat to agricultural intensification is considered to be the main cause of declines in Europe. Differential impacts on species have been recorded but insufficient knowledge of species ecology means that effective conservation management prescriptions cannot be put into place with certainty. Dietary specialisation, specifically on flowers of Fabaceae, has been hypothesised as driving differential declines but the reliability of previous studies has been questioned. Here we present a three-year study of the foraging behaviour of two UK Biodiversity Action Plan bumblebee species. For the first time, analysis of nectar and pollen foraging was performed on sites where nationally rare UK bumblebees were as abundant as more nationally ubiquitous species. Results indicated that the nationally rare Bombus sylvarum collected the majority of its pollen from flowers of Odontites verna and had a significantly narrower mean nectar dietary breadth than ecologically similar species Bombus humilis and Bombus pascuorum (p = 0.004 and 0.008 respectively). In contrast, the dietary breadth of the nationally rare B. humilis was similar to the more nationally ubiquitous species B. pascuorum and Bombus lapidarius. Moreover, B. lapidarius was recorded as having the narrowest pollen dietary breadth, collected pollen from the least number of floral taxa and was the most specialised of the Bombus species on pollen of Fabaceae. Patterns of dietary specialization were inconsistent with national declines and results highlighted a need for further detailed investigation into the factors contributing to differential declines.

Initial insights on the biodiversity potential of biosolar roofs: A London Olympic Park green roof case study

Cities dominated by impervious artificial surfaces can experience myriad negative environmental impacts. Restoration of green infrastructure has been identified as a mechanism for increasing urban resilience, enabling cities to transition towards sustainable futures in the face of climate-driven change. Building rooftops represent a viable space for integrating new green infrastructure into high density urban areas. Urban rooftops also provide prime locations for photovoltaic (PV) systems. There is increasing recognition that these two technologies can be combined to deliver reciprocal benefits in terms of energy efficiency and biodiversity targets. Scarcity of scientific evaluation of the interaction between PVs and green roofs means that the potential benefits are currently poorly understood. This study documents evidence from a biodiversity monitoring study of a substantial biosolar roof installed in the Queen Elizabeth Olympic Park. Vegetation and invertebrate communities were sampled and habitat structure measured in relation to habitat niches on the roof, including PV panels. Ninety-two plant species were recorded on the roof and variation in vegetation structure associated with proximity to PV panels was identified. Almost 50% of target invertebrate species collected were designated of conservation importance. Arthropod distribution varied in relation to habitat niches on the roof. The overall aim of the MPC green roof design was to create a mosaic of habitats to enhance biodiversity, and the results of the study suggest that PV panels can contribute to niche diversity on a green roof. Further detailed study is required to fully characterise the effects of PV panel density on biodiversity.