Florida's hammocks - areas of dense vegetation - present special problems to the builder who wants to preserve natural beauty and leave the ecology undisturbed.

Nine of the 123 houses Richard Marshall is building in the Arvida resort development of Boca West near here are in such a 31/2-acre tropical hammock preserve. The acreage features a cypress tree 20 feet around and a maple that is six feet thick at its base.

The site is also lower than the adjoining road. Florida law requires houses to be built with the floor at least 18 inches above the road level. Marshall's answer was to put the houses on poles, some ofThis construction technique raises the house above the road level and leaves the ground cover undisturbed.

The houses have no storm drainage system so all rain water soaks into the ground, giving the vegetation just as much water as before. Rather than being paved with water-diverting material, the driveways are covered with cypress mulch. Since water is scarce in Florida, not having to water to lawn is an extra advantage.

Marsall says he and his architect, William Romberger, meet with prospective buyer to be sure they are "philosophically compatible with how we want to deal with the lots."

The pole houses are all wood, with rough-swan ceder trim and tongue-and-groove ceilings and floors. Most of the woods come from the South.

The houses will sell for $100,000 to $188,000, not a high price when you consider that they are custom built and contain 2,400 to 3,700 square feet of living space.

Designed to use natural air flow rather than air conditioning, the ple houses have wood louvers along the bottom of the outside walls. These louvers let in cool air from the shaded lots. The air flows up to louvers placed near the top of the peaked ceilings at atrium walls, where it is exhausted.

According to Marshall, mechanical air conditioning will be needed only about two hours a day during tow months of the year. Actually, the air conditioning is needed more to control humidity, which in Florida can lead to mildew around the base of inside walls and in closets, Marshall said.