Rangers at Buchan County Park, near Crawley, fear arsonists may ruin their busiest tourist trade of the year.
Firefighters tackled five fires at the park near Crawley during the weekend.
The fires destroyed an acre of woodland off the main footpaths.
Rangers have stepped up patrols in the 170-acre park in a bid to prevent further damage in the run up to the Easter holiday.
The four-day weekend is the park's busiest of the year, attracting about 3,000 visitors.
Senior ranger Robin Edwards said: "It appears somebody was walking along the footpaths, randomly starting fires. We are very keen to stop whoever is responsible before the Easter weekend, so our visitors can enjoy all corners of the park."
Since 1996, when 20 acres of parkland went up in smoke, rangers have been killing some flammable bracken with herbicide in the hope of preventing further fires.
Mr Edwards said: "Now it is a matter of being vigilant. At least when we have lots of visitors during the weekend there will be more eyes looking out for troublemakers."
Fire crews from Crawley, Horley and Haywards Heath were called to four incidents in just over two hours at the park on Friday.
At 2.40pm, Crawley firefighters were alerted to heathland on fire and at 4pm crews from Horley joined them to tackle a second fire, which saw 40sqm of bushes set alight.
A third incident, half an hour later, saw part of a plantation area ignited and the final call of the day was at 4.55pm, when bushes backing on to Cottesmore Golf Club were targeted.
The final call was at 12.20pm on Saturday.
The fire brigade is treating the fires as suspicious and police have also been alerted.
Firefighters think youths started a fire which destroyed gorseland.
About 300m of standing weeds and gorse were destroyed by the fire at Park Copse in East Beach Road, Selsey, on Saturday.
Youths were seen running away from the copse shortly before the fire took hold at 1.25pm.
A member of the public alerted the fire brigade.
When crews from Selsey arrived at the scene they called for back up from Chichester.
Sussex Police have been informed.
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