More than 100 trees are being cut down at Cissbury Fields in Worthing after ash dieback was found.
Worthing Borough Council’s contractor has started felling trees at Sheepcombe Hanger which it says could pose a significant risk to the public if they were to fall.
It says it will begin to replant a variety of different trees there next winter.
Ash dieback is a chronic fungal disease that has been slowly killing ash trees in the UK and across Europe. It considerably weakens trees and results in crown dieback, which eventually renders the tree unsafe.
The council said: “In recent years, we have been felling ash trees clearly affected by the disease to ensure public woodland paths remain safe.
“Sadly, ash is one of the most common trees in West Sussex, meaning our woodlands could suffer more than most.
“Our arboricultural inspector is leading the work and has surveyed which trees need to be felled. We are still retaining trees that are showing some signs of resistance at this time.
“Disturbance will be kept to a minimum and we request that you keep dogs under close control and keep out of any areas cordoned off for the work.”