The five-year pineering Plants for Bugs project results revealed at the Wildlife Gardening Forum Conference at RHS Wisley on 17 March show that native plants are not necessarily better for wildlife than non-natives.
RHS scientists Helen Bostock and Andrew Salisbury led an examination on the value of native and non-native plant assemblages for biodiversity leading to evidence-based advice for the wildlife gardener.
Salisbury was keen to say he had discovered only preliminary results but the overwhelming conclusion was that near natives, and even one exotic plant, was as good for wildlife as natives.
They hoped to tackle wildlife planting guidance for gardeners, which is largely based on anecdotal evidence or assumptions that have been shown to be untrue, for example that nettles in gardens will attract butterflies.
One widely held assumption is that native plants are vital to attract wildlife to gardens. In fact, approximately 70 per cent of plants in the ‘average’ garden are non-native yet these gardens are rich in biodiversity.
The Plants for Bugs project tested the hypothesis that there is no difference in invertebrate diversity associated with assemblages of native, near-native and exotic garden border plants.
Plants for Bugs was a field experiment which compared invertebrate diversity on plots containing one of three plant assemblages (treatments) based on the geographical origin of the plants. These are:
- Native plants (naturally occurring in Britain and of British provenance where possible)
- Near-native plants (not native to Britain, but originating in the Northern hemisphere.
- Exotic plants (not native to Britain, but originating in the Southern hemisphere.
- The experiment consisted of 36 plots (each 3x3m) at two sites at Wisley.
By the end of 2013 more than 80,000 invertebrates had been counted and identified, including 47 different species of ground beetle, more than 50 species of spider and 16 species of butterfly.