Folk are being urged to push for more tree planting in urban areas but local authorities insist Norwich already compares favourably to other cities.
The Woodland Trust's new report - Trees and Woods at the Heart of Nature Recovery in England - calls for more trees in housing estates with less than 16pc tree cover, or 30pc canopy cover, for new developments.
Norfolk County Council, however, say the Fine City is already exceeding national averages.
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Dr Darren Moorcroft, chief executive of the Woodland Trust, said: "We've launched our campaign that lets the council know people want it to declare a nature emergency.
"We're focusing on solutions, not panic.
"There are answers to the crisis we face but we just need action – it can be done.
"Trees and woods are critical in creating better, healthier places for people to live and all communities should have access to these benefits.
"Our report calls for councils to ensure more trees on new and existing housing estates as well as improved access to woodland, so it can benefit people and nature alike."
The report arrives amid a housing boom in the area after the Greater Norwich Local Plan set out targets for where 50,000 homes would be built by 2038 in the Norwich, Broadland and South Norfolk council areas.
A spokeswoman for Norfolk County Council said: "Norwich's tree canopy coverage - the layer of leaves, branches and tree stems that cover the ground - was assessed at 18.6pc by Forest Research.
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"The city is above the national average level of cover of 16pc and compares relatively well alongside other historic cities.
"We recognise the importance of trees in our towns and cities and have been working with Norwich City Council to plant more trees within the city.
"Last year we planted 63 new street trees and this year we've developed a programme to plant 382 across the city over the next two years."
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