The charity says losing a habitat that supports 'iconic, yet threatened' species would be 'a tragedy'.
The land supports threatened wildlife such as water voles, the UK's fastest declining mammal, the charity saidArchers Green, near Welwyn Garden City in Hertfordshire, supports "iconic, yet threatened" wildlife such as water vole, skylark and harebell, the Herts and Middlesex Wildlife Trust said.
The trust said it needed to raise money to pay back a "philanthropic loan" used to take the site off the market.Image caption,Chief executive Lesley Davies said: "When the trust saw Archers Green come up for sale, they had to act fast to stop the site from falling into unsympathetic hands. "Securing the future of wild places like Archers Green is crucial for our planet and our local community.
"The complex of habitats at Archers Green is what makes it so special and home to so many different plants and animals and is why the site is a priority for the trust to give it a secure future and manage it positively to benefit its wildlife.Archers Green also flanks the River Mimram, which is one of just 240 chalk streams in the world, according to the trust.
"These unique river systems are so rare, and support some of our most endangered species - they are the UK's equivalent to tropical rainforests," the trust said.