RHS Journals
The Garden
June 2008
People: managers of the garden ecosystem
In the sixth and final part of his series on gardens as ecosystems, Ken Thompson examines the many ways in which gardeners can affect the organisms sharing their plots.
Images: Neil Hepworth
The overriding theme of this series has been the sheer diversity and inter-connectedness of wildlife in gardens. There is far more wildlife in all gardens (including yours) than you are ever likely to notice, most of it being both small and inconspicuous.
It is the nature of gardens that they are unusually diverse, both in terms of their physical structure, and the range of plants they contain. Gardens are rich both structurally and in species, and it is gardeners themselves who maintain this richness. As Jennifer Owen, who has undertaken a study of the species found in her Leicester garden for more than 20 years, has repeatedly pointed out, if you had to design a nature reserve specifically to pack as much wildlife into as small a space as possible, you could not do much better than a slightly untidy garden. Hers is the only one of Britain’s 15 million gardens that has anything approaching a complete wildlife inventory. She has made few concessions to wildlife gardening (beyond abstaining from pesticides and not being obsessively tidy), and most of the astonishing range of wildlife in her garden is present because of gardening, not despite it. Simply continuing to garden, even without particular regard for wildlife, is sufficient for most species to share our gardens.
It is crucial to grasp this point: there is no need to attempt to create simulations of ‘wild’ habitats in the garden, because gardens are real, diverse ecosystems in their own right, even if they do not resemble any ‘wild’ habitats. They are neither better nor worse than natural communities such as heathland, chalk grassland or woodland; they are merely different.
Most gardens contain a mix of trees, shrubs, herbaceous plants and lawns. All attract different species of wildlife, but even a garden’s gravelled areas, patios, fences and walls provide habitat and shelter for some wild species: lichens, mosses and their associated specialist fauna, for example. A compost heap allows detrivores to recycle nutrients, and even a pile of wood in a corner will soon be called home by a diversity of insects, some quite rare in the wild.
Neither should you lie awake at night worrying about the size or location of your garden. The results of the Biodiversity in Urban Gardens (BUGS) study in Sheffield showed neither variable is that important: small town gardens can be just as good for wildlife as large, suburban plots.
Joined-up gardening
Much wildlife gardening advice seems to be obsessed with the ‘three Bs’: bees, butterflies and birds. But gardening is naturally pollinator-friendly – after all, you, the bees and the butterflies all want the same things: lots of flowers.
Birds throw some of our odd attitudes to garden wildlife into sharp focus. Some people clearly think that birds had nowhere to live and nothing to eat before we invented nest boxes and started importing peanuts and sunflower seeds. But most garden birds do not use nest boxes, and many do not eat seeds. Between them, Britain’s population of blue tits eat at least 35 billion caterpillars every year, so there is a simple equation: fewer caterpillars equals fewer blue tits.
A keyword in the definition of an ecosystem is ‘interdependent’: it is not helpful, or even really possible, to divide up wildlife into the stuff you like and the stuff you do not. Manage any part of the garden ecosystem unsympathetically – or worse still, wage war on it – and everything can suffer.
Concentrating on the three Bs has some unhealthy side effects. Not only does it distract attention from the rest of the garden ecosystem, it can seem gardening for wildlife involves merely stocking up with nest boxes, bird-feeders and a truckload of the ‘right’ plants at the garden centre. In fact gardening for wildlife cannot be reduced to a list of plants and gadgets. Worry less about the failure of your expensive bumble-bee nest box to attract any customers, and more about recognising and enhancing the natural nesting opportunities provided to bees by the rest of your garden.
Hands off
Modern civilisation means control over our environment: air conditioning, dishwashers and mobile phones all foster the illusion that anything can be achieved by the touch of a button.
To an extent this control can be extended into the garden. As far as the plants in your garden are concerned, your control is limited only by the amount of time you are prepared to spend weeding, watering, dead-heading, staking and pruning.
The wildlife in your garden has its own interests and priorities: growing plants that slugs do not like will reduce slug damage, while more flowers will attract more pollinators, but attempts at more direct interference are likely to demonstrate merely how complicated, and poorly understood, the garden ecosystem is.
When I see a heron taking a frog from my small garden pond, how should I react? Naturally I feel a bit protective about ‘my’ frogs, but herons are wildlife too, and have to eat. Last year, most of my tadpoles fell victim to the nymphs of southern hawker dragonflies (Aeshna cyanea): I saw the adults emerging. It is impossible to compare the relative value of frogs and dragonflies; I enjoy watching both, but hope a few tadpoles survive next year.
Some gardeners mistakenly believe that magpies and sparrowhawks are responsible for recent declines in some songbirds. One or two have even taken to shooting magpies. Ultimately, this will have no effect at all on the magpie population, and there is good evidence neither magpies nor sparrowhawks have played a significant part in the decline of songbirds – domestic cats may be much more culpable.
Continued >