Investment is needed if England’s national parks are to continue providing a haven for wildlife and rare plants, a body representing the parks’ authorities said.

National Parks England, the umbrella body for the country’s 10 parks, said the increased environmental protection in the areas has allowed nature to flourish.

Statistics compiled by the body show that while the national parks cover less than 10 per cent of England’s area, they contain much higher proportions of the most wildlife-rich habitats such as heaths, fens and ancient woodlands. Up to 80 per cent of some habitats that have been identified as national priorities for conservation are within the national parks.

A spokesperson for National Parks England said: “It is not surprising, then, that national parks are havens for our native plants and animals. 87 per cent of conservation priority butterfly species and 80 per cent of priority orchid species can be found in England’s national parks.

“Dedicated management and reintroduction projects are helping special species such as the fen raft spider, the freshwater pearl mussel and the barn owl to thrive and increase their range.”

National Parks England said it believes that national park designation has provided extra protection, creating the right conditions for nature to flourish. National park authorities work with landowners, communities and a range of charities and agencies to implement conservation measures and projects. The authorities’ conservation expertise and role as planning authorities helps to protect wildlife, and support developments that enhance the natural environment.

It pointed out that England’s national parks, unlike those in some other countries, are not strict preserves where the public cannot visit. “Our National Parks are free and open to all, with 90 million visitors every year enjoying the opportunity to get closer to nature,” the spokesperson said.

English national park authorities’ central government funding was cut by 40 per cent by the last coalition Government.

The National Parks England spokesperson said: “To secure this natural value for the future, continued protection needs to be maintained across the whole of the national parks’ area. With investment the national parks can help expand and join up wildlife-rich habitats, providing even more places where nature can thrive and people can come to enjoy it.”

Jim Bailey, chair of National Parks England, said: “National parks hold sites of national and international importance, and as national park authorities we take seriously our role in looking after such special places.

“Against a backdrop of national declines in many species, we have seen notable successes. For example, the latest data on high brown fritillary butterflies on Exmoor shows the highest numbers since records began.”

The diversity of landscape in one national park, the North York Moors, includes the largest continuous expanse of heather moorland in England, 42km (26 miles) of heritage coastline and one of the largest concentrations of veteran trees in the North of England.

A North York Moors spokesperson said: “Add to this species rich grassland and heaths and it’s easy to see why the area is such a haven for wildlife. The North York Moors is the southernmost place for dwarf cornel and is home to the most northerly colony of the Duke of Burgundy butterfly in Britain.

“Whales and dolphins including minke, fin, sei, pilot and humpback are regularly spotted off the national park’s coastline and, earlier this year, hundreds of people flocked to Sutton Bank National Park Centre to see its turtle doves.”

Andy Wilson, chief executive of the North York Moors National Park Authority, added: “The wildlife of the North York Moors is undoubtedly one of its charms, be it the huge variety of birds that provide a melodic soundtrack to a moorland walk or the thrill of spotting a whale surfacing off the coast.

“The National Park’s pioneering Farm Scheme had a big impact on the area’s wildlife providing grants and support to farmers to maintain and introduce traditional boundaries such as stone walls and hedges, woodland and hay meadows – all valuable habitats.

“Our work with farmers and those who manage the land continues today to restore and link habitats, protect water resources, manage our woodland and a host of other projects to help our wildlife continue and hopefully to thrive.”

Secretary of State for the Environment Liz Truss said: “Our national parks are some of the UK’s most beautiful natural environments which we want everyone to enjoy.

“They are home to our native plants and spectacular wildlife, from the stunning orchids in the South Downs to the ospreys that return each year to breed in the Lake District. They boost our rural economies with visitors spending £4bn each year and bring together local communities helping the countryside and its businesses to thrive.”