OAKLAND, CALIF. — THE spectacle of residents here returning to homes where nothing is left but a chimney is sending a five-alarm warning across the United States.In a nation where cities are expanding into suburbs and suburbs into "exurbs," experts say Oakland typifies "the fire of the future," a place where housing developments meet wildlands and the results are too often combustible. The risks are probably the most pronounced in California, but they extend way beyond this rapidly growing state. The development of what were once wild areas on the outskirts of cities, the building of homes on the edge of national parks and pristine forests, dense development in urban hills and canyons lands - all pose new challenges to firefighters. Experts say preventing such debacles as occurred here, where 2,700 dwellings were destroyed in the worst fire in US history, requires new firefighting techniques, changes in urban planning, and sacrifices by home owners. "As the population grows, as we take over more wildland areas, there are no buffer zones between ground cover and homes," says James Covington, an instructor at the National Fire Academy in Maryland. "Whenever you have small brush fires, they can run right up to buildings." No longer, say experts, can city fire departments be content knowing just how to put out structure fires, nor can state and federal agencies be schooled only in wildland techniques. Departments today need off-road vehicles as well as traditional "pumpers," and ground crews that can create fire breaks. "I think this is the fire of the future," says Charlie Johnson of the Santa Barbara Fire Department, which last year fought the "painted cave" blaze that destroyed 600 structures. The Oakland fire also highlights the need for new command structures to handle large-scale emergencies. At the peak, more than 1,400 firefighters and several hundred pieces of equipment - including planes and helicopters - were enlisted to battle the 1,800-acre blaze. Traditionally, departments have used top-down command structures, with one person directing the operation. Now, says Mr. Covington, departments need to use "incident command systems" that decentralize tasks, allowing greater flexibility. Although the Oakland fire department was using this management approach, some firefighters have complained of confusion and lack of direction that left them idle during phases of the operation. Much of the responsibility for reducing the fire danger in urban-rural areas will fall to governments and homeowners. Fire authorities emphasize the need for adequate water supplies in new developments. This means not only the systems that emergency crews would tap - several reservoirs went dry in the early stages of the Oakland fire after pumping plants failed - but also reserve supplies at homes. The state Department of Forestry recommends that each homeowner have at least 2,500 gallons of emergency water on hand. To allow easy access to dwellings in rugged areas, fire officials stress the need for adequate roads. Homeowners, officials believe, must adopt an new fire-safety ethic. This means new fire-retardant building materials and new approaches to landscaping. Some residents that rebuilt after the Santa Barbara have moved homes away from ledges and created vegetation-free buffer zones around their dwellings. "This is not just a fire department problem," says Mr. Johnson. "It is a community problem." Oakland officials are being criticized for their handling of a small brush fire last Saturday that precipitated the inferno. Fire officials thought the small blaze - the origin of which has been "classified as suspicious in nature was under control and they left it unmonitored at times. Gusting winds whipped it into the conflagration it became the next day. Local officials reacted angrily this week to all the post-tragedy finger pointing. "I don't think anything could have been done differently," said one fire official. "This was a true freak of nature."