As G7 leaders meet in Cornwall to discuss global issues, the county’s nature is in decline, according to conservationists.

The Cornwall Wildlife Trust said almost a quarter of all terrestrial mammals and butterfly species were at risk and 12% of species of principal importance were threatened with local extinction.

Since 1990, 150km (93 miles) of Cornish hedges have been lost, it added.

The trust said intensive farming and climate change were among the biggest threats to nature on land, while at sea the most significant threats were from intensive fishing and pollution.

The State of Nature Cornwall 2020 report was inspired by the UK State of Nature report of 2019, which revealed that 41% of species studied in the UK since the 1970s are in decline.

The study was carried out in conjunction with Cornwall Council and the University of Exeter to analyse habitat data collected largely by volunteers.

It shows the trend of declines is in line with the rest of the UK over the last 30 years and while a few species have prospered, the overall findings support claims of an ecological crisis.

Carolyn Cadman, chief executive of Cornwall Wildlife Trust, said: “Our analysis shows that Cornwall’s wildlife and wild places are in trouble and we need to take action now to reverse the decline.

“The UK is one of the most nature-depleted countries in the world and here in Cornwall the beauty of our coasts and countryside masks the pressures which nature faces.

“We know what to do to bring nature back. With additional investment, some changes may be reversed through species reintroductions and nature recovery programmes, which we are already undertaking.

“However, it is also vital that the UK Government makes good on its commitment to strong, world-leading environmental laws and protection, and increases investment in nature on a national scale, to create wildlife habitats which are bigger, better managed and more joined-up.”

Climate change will be much discussed at the G7 summit.

Cornwall’s average temperature has increased by one centigrade in the last 34 years – compared with a five centigrade rise in the last 20,000 years.

The report also considers the actions that can be taken at local and national levels to help nature recover.

Cheryl Marriott, head of conservation at the Cornwall Wildlife Trust, said: “The efforts of local wildlife groups, organisations and projects to monitor and protect Cornwall’s nature are outstanding.

“Without their sightings, records and evidence, the State of Nature Cornwall report would not have been possible.

“We all need to do more to protect wildlife and wild places. Government policies must change and both national and international action needs to be stepped up as a matter of urgency.”