In conjunction with the Wildlife Trusts and the RSPB, the Royal Horticultural Society staged a one-day conference in Birmigham on 3rd December 2002 entitled Gardens: Heaven or Hell for Wildlife?
The invited audience heard contributions from Sir Richard Carew Pole (RHS President), John MacLeod (RHS Professor of Horticulture), Rt Hon John Gummer MP, Professor Kevin Gaston and Dr Ken Thompson (University of Sheffield), Dr Andy Evans (Head of Terrestrial Research, RSPB), Ifer Gwyn (Snowdonia Wildlife Gardening Project), Chris Baines (writer, broadcaster and wildlife gardening guru), Maggie McDonald (Wiltshire Wildlife Trust Green Gardening Project Officer), Karen Simms-Neighbour (Urban Parks Forum), Mike Snowdon (retired head gardener, Rowellane Garden, Northern Ireland) and Matthew Wilson (curator, RHS Hyde Hall).
Such a gathering of prominent figures and organisations from the world of gardening and wildlife conservation in the UK indicates, I believe, how wildlife gardening/garden biodiversity, is steadily climbing up the agenda both in horticultural and conservation circles. John Mcleod stated the aims of the conference thus: 'The whole aim of [this conference], working with our partners, is to create an awareness of the environment potential of gardens.
The whole aim of [this conference], working with our partners, is to create an awareness of the environment potential of gardens.'
Discussion was wide-ranging and interesting: for proceedings and full audio transcripts for each speaker, follow the source link below. Reading these transcripts, I was fascinated by the research of Professor Kevin Gaston and Dr Ken Thompson of the University of Sheffield which suggested to them that there was 'no evidence at all that the number of native plants in your garden has any effect on the invertebrate wildlife which your garden supports
Prof. Gaston and Dr Thompson
no evidence at all that the number of native plants in your garden has any effect on the invertebrate wildlife which your garden supports'.
This assertion, which contradicts what is popularly believed about wildlife in gardens, was not critically examined in detail during the conference. The conclusion was based on the results of sampling that showed that gardens with greater numbers of native plants did not yield greater numbers, or diversity, of invertebrates. Invertebrates were sampled by means of malaise traps, pitfall traps, and directly searching leaf-litter and vegetation surfaces. The major problem, as I see it, with their conclusion is that the wildlife value of a garden cannot be gauged simply by the number and variety of invertebrates which can be caught there, particularly by such indiscriminate means as malaise traps
The major problem, as I see it, with their conclusion is that the wildlife value of a garden cannot be gauged simply by the number and variety of invertebrates which can be caught there, particularly by such indiscriminate means as malaise traps.
Insects are famously mobile animals: look at the speed with which a new pond is colonised by them. I would guess that the majority of insects which pass through a garden over a period of time do not stop there at all; they are simply passing through on their way to somewhere else (just like many of the birds which fly over my garden but will never land there). But a malaise trap will not distinguish between those that are using the garden and those that are not; it will just 'hoover' the whole lot up indiscriminately and therefore mask any real differences between gardens with native plants and those without.
I would prefer to see more concentration on sampling methods which favour animals that actually use the garden to fulfil some aspect of their life cycle
If the malaise traps had been placed in the middle of the tarmac roads outside the properties sampled, they would probably still have yielded quite impressive catches; but what can we conclude about the suitability of tarmac for wildlife from that? I would prefer to see more concentration on sampling methods which favour animals that actually use the garden to fulfil some aspect of their life cycle as opposed to those which are merely passing by. I remain convinced that by doing this we would see that native plants are disproportionately more useful to invertebrates in the provision of food (other than pollen and nectar), hibernating and breeding sites and in meeting other specific life-cycle requirements that native animals have developed over thousands of years of co-evolution with our native plants.