BETWEEN the high-technology ribbons of Route 128 and Interstate 495, an older industry is quietly growing up almost unnoticed - forestry. True, the profits are not as spectacular as those in the computer industry. But state officials say that forestry and related industries are vital to the Massachusetts economy. And, they point out, the trees are not all located in the western part of the state.
For instance, says James M. MacArthur, forest products marketing and utilization specialist with the state Department of Environmental Management, there are 50 tree farms on the North Shore alone. Most are small, he says, averaging only 25 acres each.
In a given year, these farms may not individually produce much timber, or revenue for the owners, Mr. MacArthur says. But collectively their benefit is great.
Managing small forests rather than letting them grow wild makes them much more productive, MacArthur explains. It also provides increased wildlife habitat , conserves land, protects water supplies, and often provides natural areas for recreation.
Massachusetts tree farms supply major wood-products industries, which provide employment for almost 45,000 workers and generate more than $1 billion in revenue, he adds.
MacArthur and other state officials are promoting the American Tree Farm system, a national program that encourages private forest owners to grow trees as a crop.
Jim Dennesen, a forester with the New England Forestry Foundation, says the tree farmer ''has the means to earn an annual, though not substantial, revenue.'' He points out that William E. Dorman, owner of the 155-acre Herrick Tree Farm in Boxford, Mass., harvested enough wood last year to build an average-size house just from ''thinning'' an unmanaged section of the farm. He won't get such a large harvest from that particular area for another 15 years, Mr. Dennesen says. But by thinning that section, he explains, the owner makes it possible for the remaining trees to grow much more quickly.
At the nearby Elmlea Tree Farm, Jack Jackson, a forester with the state division of Forests and Parks, points to a stand of red pines planted in 1939. Exhibiting a sample bored from one tree, he says that until five years ago it had been growing at a rate of about an inch in diameter every five or six years.
The stand was thinned about five years ago, giving the remaining trees more access to sunlight. The result, says Mr. Jackson, is that the growth rate has almost doubled. The tree from which the earlier boring was taken has grown an inch in diameter in the last three years alone, according to Jackson.
Besides producing timber for wood products, tree farmers can expect to harvest half a cord to a full cord of firewood from each acre annually, says Dennesen.
Mr. Dorman is growing Christmas trees on part of his property. These provide a good return on the investment and take much less time to mature than trees used for timber, Dennesen explains.
In addition to their income from wood, forest owners get a 95 percent rebate from the state on their property taxes. Jackson says, ''This is very substantial'' in the Boston area, where property values are so high. At least 30 other states provide similar rebates.
Jackson says that to get the rebate a landowner must follow a forest management plan designed by either the New England Forestry Foundation or one of several private forestry consultants. The plan requires building a fire access road and making sure trees are harvested properly. The state monitors compliance with the plan, and requires a 10-year commitment to tree farming.
Tree farmers are motivated by more than the modest income from their wood, says MacArthur. Many do it for conservation purposes or simply ''for the love of the land.''
The program is becoming more popular and better known in Massachusetts, he says. He expects to receive as many as 600 new applications this year and foresees a tripling of the 300,000 acres now in tree farms in Massachusetts in coming years.
At the turn of the century, says Dennesan, only 20 percent of the state was covered with forests - a result of poor logging practices. Now, he says, that figure has reached 65 percent.
He points out that good forest management also takes into account wildlife needs. In an unmanaged forest, he says, little sunlight reaches the forest floor. Little underbrush grows, and there is not much protection for wildlife. In a managed forest, Dennesen explains, small areas are left open to the sunlight, allowing the necessary cover to grow.
Small tree farms are vital to the strength of the ''forest products industries'' in Massachusetts, MacArthur says. These industries include not only logging operations and the 152 sawmills in the state, but also furniture and cabinet makers, and pulp and paper manufacturing operations.
MacArthur provides market research information for manufacturers of wood products and uses various techniques to help them sell market their products. He is also organizing an international wood-products trade fair to be held in Boston next year.
''A lot of us take forestry for granted,'' he says. ''You have to show people where the chair, wood in the pencil, and paper towels come from,'' he says.