Dig a pond to help city wildlife, gardeners told

Londoners must do more to attract animals to their gardens, wildlife experts claimed at the launch of a green campaign today.

The campaign aims to safeguard animals such as frogs, toads and hedgehogs which are rapidly disappearing in the capital.

As a study revealed that there were more than 3.2 million gardens in London covering 93,757 acres - equivalent to 37 Richmond Parks - the London Wildlife Trust, backed by Boris Johnson, said they could be vital in fighting climate change and protecting wildlife.

The Garden For A Living London campaign aims to transform private spaces into a network of mini nature reserves. Organisers are asking homeownersto sign an online pledge to make theirs more animal friendly. "We want to highlight the incredible importance of the capital's gardens to wildlife and to people," said the trust's chief executive, Carlo Laurenzi. "In urban areas especially, gardens will help reduce the impacts of climate change. They provide shade, absorb carbon, soak up flood water, retain water and help to cool the city.

"They also provide vital habitat for wildlife - and a strong network of wildlife- and climate-friendly gardens stretching across the capital will provide room for species to move freely and adapt to our changing climate."

The trust has come up with seven actions for homeowners, which include building a pond, planting hedgerows and changing to drought-resistant plants.

Previous research has found the increasing number of patios and the spread of decking in gardens were having an adverse effect on animal and bird numbers.

The Mayor said: "London's gardens not only make life more pleasant for millions of people, they can also be a veritable treasure trove of wildlife. I have pledged to protect our gardens from being eaten up by developers, so I welcome the London Wildlife Trust's campaign."

Thames Water is also supporting the campaign. Sustainability director Richard Aylard said: "Our customers and local communities are at the heart of everything we do, and we know that many of them are passionate about their gardens. By supporting the campaign we can help them to achieve wonderful results with a minimum of water."

The campaign is being officially launched today at the trust's Future Garden at the RHS Hampton Court Flower Show.