The idyllic British scene of sheep and cattle grazing in the countryside could become a thing of the past, rural landowners have warned.
Pastoral landscapes could become scrubland, the CLA has warned
The Country Land and Business Association fears new EU funding rules will see farmers giving up livestock.
The government is due to announce in the next few days how common farming reforms will affect England and Wales.
The CLA prediction is made in a report to be launched on Monday at the Royal Agricultural Show in Warwickshire.
A key change will be that instead of being subsidised for each animal reared, farmers will receive a flat payment regardless of how they use the land.
Monday's report says this could lead to further big declines in the number of sheep and cattle with much of our pastoral landscape being abandoned and reverting to scrub.
It argues that the environmental benefits of livestock grazing can only be protected with better government promotion of British meat.
The CLA also calls for fairer returns for dairy farmers who are struggling to make profit from the production of milk.
The Royal Show at Stoneleigh Park opened on Sunday.
The show, one of the highlights of the farming and agricultural calendar attracted around 160,000 visitors last year with organisers hoping for an even bigger crowd this time around.
One of the more unusual attractions at the four-day event will be a display of lingerie made from stinging nettles, designed by student Alex Dear.