Gardens as a resource for wildlife
Written by Steve Head Reviewed by Ken Thompson
This website is all about the extraordinary abundance of wildlife that occupies our gardens, how they live, and ways we can manage our gardens better with wildlife in mind. Most of the site’s content is about the quality of the garden habitat, but it is important to think of the quantity of habitat too.
How substantial is the garden habitat resource? What are its main features? The information below is a summary from our leaflet The Garden Resource which has more information, lists sources and provides an explanation of how the figures have been arrived at.
Number, size and area
About 87% of households in the UK have gardens, so there are getting on for 23 million gardens. This is an overall figure, and the proportion is less in large cities where flat-dwelling is typical. In London, it is about 61%. Gardens vary in size from 3.6m2 to over 2,200m2 but studies indicate an average of about 190m2. As we might expect, mid-terrace houses are a quarter the size of detached house gardens.
Bigger gardens are more able to contain hedges, mature trees and big shrubs that are all good for some wildlife, but having lots of small gardens in a terraced neighbourhood could mean more compost heaps and ponds, certainly small gardens are just as good for wildlife as large ones.
The total area of gardens in the UK is estimated at about 433,000 hectares or 4,330 square kilometres, a bit more than a fifth the size of Wales. This is a colossal resource of national significance for the thousands of generalist species that can live in gardens.
Loss or gain?
Mature, wildlife-rich gardens continue to be lost from the UK garden resource through “garden grabbing” and until recently gardens were regarded as brown-field sites appropriate for new house building. In 2010, 25% of new homes were built on previously residential land, rising to 71% in the Chilterns.
New-build houses are currently completed at the rate of about 114,000 per annum in England, but their gardens are much smaller than the 190 m2 national average across all housing stock, with an average size of only 113.4m2. Only one in five new houses achieves the 190 m2 average.
In London, where very accurate measurements of garden stock have been made, the equivalent of 2.5 Hyde Parks of vegetated garden area have been lost annually from 1998 to 2008. Much of this is not loss of complete gardens, but loss within gardens from changes in their use, with hard surfacing of front gardens for car parking. In back gardens, lawns, trees and mixed vegetation in back gardens, have been replaced by patios, decking, sheds and greenhouses.
Loss of mature garden space in inner cities is a very worrying trend, since gardens contribute 50% of urban green space, and this resource is so important for human health and wellbeing. Look at the Gardens in the Urban Setting and Wildlife Gardening and People sections of this website for more information on these issues.
Turnover of gardens
Gardens might be even better for wildlife if they didn’t change hands so often, which generally involves a greater or lesser garden makeover. Only a third of owner-occupiers have been in their present house for twenty years or more, and the average ownership is 11 years.
Private rented property changes hands swiftly, with more than a third of tenants occupying for less than a year. New owners may remove good wildlife features (like ponds) but of course could add others more to their taste, This makes gardens very temporary habitats, but probably contributes to the variety of opportunities they provide for wildlife.
There’s good news here, because about 16% of gardens contain ponds, so the total could add up to 3.5 million garden ponds, providing a total of about 350 hectares of pond habitat, which is a quarter the area of Lake Windemere.
More significantly, there are only about 430,000 countryside ponds left in Britain, so our garden ponds, which are usually a lot smaller than country ponds, nevertheless form a large resource, and means nowhere in the lowlands is far from a pond. See our Ponds and Water page for more information.
There are getting on for 30 million trees in our gardens, which make up about a quarter of the national resource of trees outside woodland. Garden tree cover extends to over 47,000 hectares, not far short of the 56,600 hectares of the New Forest National Park. The trend to smaller gardens in new-build will limit the overall garden tree resource, but this could be offset by tree planting in communal green space.
Three in five UK gardeners try to help their wildlife by feeding the birds, putting up nest boxes, or choosing to grow wildlife-friendly plants. We reckon there are about 7 million garden nest boxes, and in total we spend £200m every year on bird food. This augmentation of the resources birds can find in gardens has given a city like Sheffield six times the national bird density across the country as a whole!