Cattle are to be introduced to Warren Hill, near Storrington as a conservation measure by the National Trust.
It will be the first time grazing animals will have been on the site since 1920.
The National Trust is aiming to bring some cows from Woolbeding Common to graze at Warren Hill for a very short time each year to help manage the heather.
The Trust also manages Sullington Warren, where it has kept up with the invasion of trees across the heather and changed the age structure of the heather by mowing and removing the cuttings.
But at Warren Hill, between Georges Lane and Washington, the story is different.
Warden Vic Oliver said: “We have removed tree roots and then used cuttings from Sullington Warren to restore neglected heathland with good results. It resulted in young vigorous heather growing in the sunshine, with opportunities for insects, mammals and birds to explore.
“However, things continue to change. The trees are fighting back, with birch trees marching across the heather.
“We have cut and sprayed the birch and brambles, but we are fighting a losing battle.”
He said there were not enough volunteers or time to manage Sullington Warren and Warren Hill.
Introduction of grazing animlas to a small part of Warren Hill will manage the heather.
He explained: “We will aim to graze the area in late summer to avoid damaging the daffodils and bluebells. We hope to bring some cows from Woolbeding Common to graze at Warren Hill for a very short time each year.”
The cows are Belted Galloways, originating from moorland in South East Scotland,
Warren Hill last saw grazing animals in 1920 when the Lloyd family took over the estate and planted up some of the poorer fields with trees.
The change to Warren Hill will mean reinstating some of an old fenceline and putting in five gates, which will only be in place when the cows are grazing, then removed.
The whole area will still be open access and people will be able to walk freely.
“We are telling as many people as possible about the changes – what we are doing and why we are doing it,” said Mr Oliver.
The fence installation will be carried out this autumn by National Trust wardens and volunteers.
The National Trust welcomes volunteers and anyone wanting to help should ring 07768 065372.