by Charles H. Smith Whether or not you care about the long-run future of the world's forests, ecology issues probably haven't had any impact on your business up until now. But that is likely to change. Increasingly, customers are asking questions about the environmental impact of using wood products in building projects. To answer such concerns, builders can now locate "certified lumber" and other ecologically sound wood products in the commercial marketplace. Small suppliers such as San Francisco's EcoTimber International are offering lesser-known woods like Narra, a subtropical hardwood, as substitutes for mahogany in finish work and furniture. Eco-friendly wood is going mainstream: Home Depot, the giant Atlantabased home center chain, is stocking "environmental" pine in a specially marked section of its stores. Independent certification. In the past, it has been hard 0/JLC