Quadbikes and off-road vehicles are causing irreparable damage to chalky ground to the north of the city, a reader has complained.
Sarah Hall said the grassy area at the top of Chalkpit Lane was home to flora and fauna that was being destroyed by tyre tracks.
The land south west of the car parks can be accessed on foot but Sarah said the South Downs National Park Authority had not intervened.
She said: “I have contacted Goodwood about it and, when they see people doing this, they have a word, but the land does not belong to them, so that have no authority to ban it.
“It does not belong to West Dean Estate either, so I don’t know who to turn to now.
“The part they choose to drive on holds many species from cowslips, harebells and scabious to orchids.
“Slowly but surely, these precious plants are being scoured out by these thoughtless people.”
The South Downs National Park Authority (SDNPA) has been approached for comment.
It comes as the SDNP Trust continues to appeal for help restoring parts of the South Downs Way, including Chichester’s Millpond Bottom between Beacon Hill and Penn Hill, which has ‘impressive scaring’.
The appeal reads: “Successive feet, wheels and hooves have more than doubled the width of the chalk track – putting nearby sensitive Scheduled Ancient Monuments at risk.
“We need £10,000 to safely transport materials to the site, mend the trail and keep walkers on the straight and narrow.”
Andy Gattiker, South Downs Way trail officer, said: “Our existing funding allows us to make most repairs but there are a number of significant projects which, because they are on more remote sections of the path, are too expensive to tackle using existing funds.
“Each year, as the erosion and mud gets worse, they get more damaged and become harder to fix.”