A suggestion that livestock should be removed from upland areas to protect their ecosystems has provoked an angry reaction from a Welsh farming union.
In a book by George Monbiot, the author claims that sheep have reduced most of the uplands to "bowling greens with contours''.
The Farmers' Union of Wales (FUW) has hit back by commissioning a report based on the role of grazing animals and agriculture in the Cambrian mountains - a major upland area in mid-Wales.
The report, written by former joint nature conservancy committee member and Countryside Council for Wales board member, Dr Ieuan Joyce, highlights that agriculture and grazing livestock have played a central role in creating and maintaining the landscape for thousands of years.
FUW hill farming committee chairman Derek Morgan, who farms on the eastern slopes of the Cambrians, said farming and grazing animals had become an inherent part of the landscape and upland ecosystems.
"This major report vividly highlights not only the dependency of upland species on agriculture, but also the key role that agriculture should play in terms of addressing the challenges of the coming centuries,'' he said.
According to the report, management by farmers has not only enabled the production of high-quality food, but also led to the development of internationally important semi-natural ecosystems.
Mr Morgan said the assertion that uplands should be left to go wild was an attack on the Welsh communities who had farmed the mountains for thousands of years.
"The vast majority of farmers and some conservationists are on the same page on this, particularly as undergrazing becomes recognised as a problem for many species,'' he said. "We need to build on that understanding and recognition. Wilding on the Cambrians would be akin to the herding of American Indians on to reserves in order to satisfy a romantic whim - and result in the destruction of existing ecosystems.''