The cause of the problem, according to the trust, is the change in the farm support system which has been heralded by the Government as having absolutely the opposite effect in rewarding small farmers for their work in conserving the countryside and wildlife.
And after an economic survey of land covering some 370,000 acres, it says that 60 of their tenant farmers will be forced out of business by 2012.
The report is already causing a major rift between the trust and the Government. The Department of the Environment, Food and Rural Affairs rushed out a statement yesterday saying the report was "absolutely wrong."
But there was strong support for the trust amongst Yorkshire Dales hill farmers, who tend most of the land in the national park, conserving the landscape which brings in hundreds of thousands of visitors each year.
Our countryside commentator John Sheard, who has been writing about the problems of hill farms for more than 40 years, will give his pungent view on this situation in A Week in the Country on Friday.