Suffolk farmers have hit back at a suggestion that sheep are the "principal obstacle" to nature recovery - and have a "brutal impact" on landscapes.

A Twitter article by financier and environmentalist Ben Goldsmith in which he suggests Britain's sheep have got to go has provoked fury.

"The unavoidable truth is that sheep are the principal obstacle standing in the way of meaningful nature recovery in Britain’s national parks and other agriculturally marginal landscapes," he said.

"It is because of forensic grazing by tens of millions of sheep that great swathes of Britain are largely of trees and scrub, and impoverished of wildflowers, birdsong, wildlife."

Sheep are used in many different landscapes in Suffolk - including salt marshes along the coast. They are also seen as useful in adding nutrients to the soil in crop fields post harvest - enabling farmers to cut the use of artificial fertilisers.

Organic farmer John Pawsey at Shimpling Park near Bury St Edmunds uses them to graze clover he has sown so that combined, they can improve fertility in his crop fields in a more natural way.

National Trust Ranger Andrew Capell keeps rare sheep flocks to preserve precious landscapes including Sutton Hoo and Orfordness and pointed out that without them he would have to use heavy mowers.

The sheep create a "mosaic" of sward heights which helps nature, he said. "They are selective grazers - they like the sweet young grass." Larger herbivores tended to graze landscapes to one height, he explained.

However, it was possible to over-graze and it was important to keep control of numbers, he added.

"You have got to get the balance right and not over-stock," he said. "Last year we had record numbers of lapwings, avocet and redshank breeding pairs because we were getting the habitat right with the use of sheep and a little bit of mowing."

Lady Caroline Cranbrook, whose family farms sheep at Great Glemham, near Saxmundham, said downs, fells, saltmarshes and meadows had largely been created by the sheep, cattle and horses that grazed them.

They had made wild landscapes more accessible to walkers. Where land is no longer grazed in southern Europe, it has become virtually inaccessible, she added.

"They have been responsible for much of the appearance and biodiversity of the English landscape, including parkland and pastures in Suffolk.

"As Princess Anne memorably said at a Sentry conference a few years ago, abandoned land becomes inaccessible land. So, for many reasons sheep farming is important to us all.

"In East Anglia, the home of so much sheep farming, the prosperity it created enabled the building of many of our beautiful churches.

"Sheep farming is part of our cultural heritage and sheep have always been important for food and agriculture – and the environment.

"They remain so today and we rely on the Department for Environment, Food and Rural Affairs (DEFRA) to help underpin the industry with their support."

National Sheep Association chief executive Phil Stocker  pointed out that sheep have been in the British Isles since the Neolithic times.

"It is no accident that most of our National Parks are in areas predominated for generations by grassland and sheep," he said

He conceded there may have been a time when UK farming solely focused on production but said it had increasingly moved to farming practices that consider the wider environment.