More than 2,000 gorse blazes in Northern Ireland were attended by firefighters last year, the service said.
Most were started deliberately or because of thoughtless or careless behaviour, according to assistant chief fire officer Dale Ashford. Failing to extinguish cigarettes properly or leaving barbecues unattended are among common causes.
Around 55 fires a day required the emergency service during the first week of last April, the service said.
Mr Ashford said: "Dealing with these types of incidents puts not only firefighters' lives at risk but the lives of everyone in the local community and puts additional pressure on Northern Ireland Fire and Rescue Service (NIFRS) resources.
"People need to realise that we simply cannot be in two places at once and fighting gorse fires mean that fire appliances and firefighters are diverted from other potentially life-threatening emergency incidents in the local community."
He added: "We would ask that people be vigilant when out and about during the Easter break for anyone starting fires deliberately and any suspicious behaviour should be reported to the police immediately."
The number of gorse fires in recent years has decreased. During the financial year ending last March 2,088 incidents required the emergency services. That compares to 3,651 in 2011/12. The number of hoax calls for which firefighters were mobilised was 488 last year compared to 770 in 2011/12.
The tally of hoaxes and attacks on crews tends to peak over the Easter holidays.