Longhouses, the characteristic dwelling of many Dayak groups, require a great many plant species for building materials. To sustain their supply of materials, Dayaks have always protected their forests. Today we recognize the need for more forest cover for the earth, which may die without it. Indeed, the need for forests and, more importantly, for biological diversity is now becoming obvious. This diversity is important for people as well as nature. In the past, when Dayaks could still practice their traditional way of life, they helped maintain biological diversity.