significantly higher bumblebee species were observed within the solar plots. This result reflects the sowing of these solar plots with wild flower mixes providing suitable forage for a wide range of invertebrates. Further, at Site 10, the relative longevity of the site (4 years) is likely to influence this result. At Site 7, the highest bumblebee diversity of all solar plots was observed (10 species), even though this was not significantly higher than its control plot. For this site, too, botanical diversity is the reason for high invertebrate diversity: Site 7 displays the second highest plant diversity of all the solar plots.
7.1.21 On the majority of solar farms included in this survey, invertebrate species richness was generally not significantly different between solar plot and control plot on a site-by-site basis (although overall, butterfly diversity was higher on solar plots). This is because the botanical diversity on many of the solar plots is still quite low and based upon an agricultural seed mix. However, as botany improves over time in response to favourable management, so invertebrate diversity would be expected to improve. In addition, the solar farms
are relatively new features of the landscape, and so even where there is higher botanical diversity it will take some time for species to discover and utilise the sites.
7.1.22 Agricultural flowers such as white clover or crops such as oil seed rape may attract an abundance of bees, but this is likely to be short lived (3-4 weeks of the year) and benefit only a few species. To benefit a high diversity of invertebrate species in larger numbers, it is necessary to sow a meadow with a range of grass and wild flower species. Higher plant diversity will have the added benefit of providing early and late season flowering which in turn will provide nectar sources at times of year when food sources for bumblebees are in short supply.
7.1.23 The results of the surveys indicate that solar farms can have a part to play in ecosystem services, through increasing the abundance and diversity of pollinator species. They may act as an important reservoir of pollinating invertebrates, particularly within intensively farmed landscapes where other suitable habitats are scarce. The fact that generally solar farms are constructed on land of poor agricultural value may mean that the economic benefits of providing a pollinating invertebrate resource (and thus benefitting adjacent agricultural land) may outweigh that of planting crops within the site. Additional indirect ecosystem services may be through the reduction in agricultural inputs leading to cleaner groundwater or adjacent waterbodies. Further study may look at calculating the economic value of solar farms in terms of their ecosystem services.
Can solar farms encourage a greater diversity of birds?
7.1.24 The conclusions reached so far indicate that solar farms can support a greater diversity of plants as well as greater numbers of butterflies and bumblebees, particularly under management which focuses on optimising