THE Provisional Airport Authority is providing $8 million to plant 60 hectares of trees on north Lantau island adjacent to the new town at Tung Chung. An environmental assessment of Chek Lap Kok has determined a significant amount of natural habitat would be destroyed during construction. This habitat is being replaced by more than 100 varieties of native Hongkong tree species from the Agricultural and Fisheries Department nurseries. ''The initial phase of planting is to start this summer,'' said Nigel Blandford, the landscape architect of the Southwest New Territories Development Office. The planting will take place in four areas on the slopes above Tung Chung. About 20 hectares of natural woodland, along with coastal mangrove trees and animals, such as the Romer Tree Frog, are also losing their habitat during the development of Chek Lap Kok. ''We are just about to start on the compensatory planting to replace the 20 hectares of woodland, and we are proposing to plant 60 hectares on the slopes of Lantau, making it a three-to-one replacement,'' Mr Blandford said. Intended more to conserve the environment than for public recreation, the planting takes place in an area that was formerly heavily forested, and which is now only lightly vegetated, after years of logging and fires. ''It is not really for people to walk in or to look at but is a natural habitat for animals and birds,'' Mr Blandford said. Phase 1 of the project begins this year and includes 87,000 trees. According to Mr Blandford, a term contractor will start planting at the end of this month. ''It's a fairly random mixture of species, and the Hongkong University Botany Department is going to monitor these trees,'' he said. ''It's a kind of experiment. We are going to see what grows best,'' he said, adding that a trial plot was under way to monitor growth rates. As a safety measure, a fire break was being created between the Tung Chung woodland and the newly planted slopes. ''If you go back several hundred years, the natural part of this place is forest. The only reason that it doesn't recover is fire. Where it is replanted, it thrives.'' Mr Blandford said costal mangroves would also be included in the replanting. ''We are looking for areas for the planting of coastal mangrove. They are important habitat-nursery areas for fish.'' Conservation has been an important aspect of north Lantau development from its beginning. ''There are people in the Government trying to make sure we end up with an environmentally friendly development,'' he said. ''The Territory Development Department, the Agriculture and Fisheries Department, and the Environmental Protection Department are trying to do that.''