By TATIANA SCHLOSSBERG

In a move aimed at curbing the unlawful use of the Greenlands by dirt bikers, the West Tisbury conservation commission voted Tuesday night to put up five new warning signs at entrances to the preserved area.

The vote comes in response to several complaints received by the environmental police and a group called the Friends of the Greenlands.

Steve Maxner, a member of the friends group, asked for 12 signs, to be placed at all access points to the town conservation property, but the commission lowered the number.

Located adjacent to the state forest, the Greenlands were conserved and set aside in the 1980s for aquifer protection.

At the commission meeting Tuesday, it was noted that Massachusetts state law and a West Tisbury town bylaw are already in place to address the problem. The state law includes heavy penalties — a $250 fine for the first offense, and a $1,000 fine and seizure of the vehicle on a second offense. The town bylaw includes a $25 fine for first-time offenders and less than $50 for subsequent offenses.

But apprehending offenders is easier said than done since bikers generally wear helmets or masks and are riding unregistered vehicles. “When I try to stop them, they flip me the bird and they’re just like, get lost,” said Mr. Maxner.

The commission agreed that while the signs may do little to stop trespassing bikers or other flagrant behavior, they will help spread the word that the riding is illegal and does carry a severe fine.