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The spruce-fir forest cover type, occupying nearly 8 million acres in Maine, accounts for approximately 50 percent of the growing stock volume in the State. A similar portion of Maine's commercial forest land is owned and managed by forest industry, with spruce and fir being the mainstay of the industry.

Analyses in recent years of Maine's timber supply have shown softwood removals to exceed growth. The dramatic effects of the spruce budworm (Choristoneura.fumiferana (Clemens)) on the spruce-fir forest of Maine has heightened concern over the timber supply. A greater emphasis on management is necessary if timber growth is to keep pace with demand. With increasing demand for timber, and the increasing value of timber products, intensive management is becoming economically feasible. High labor costs have led to an increase in mechanized harvesting. Consequently, the stage has been set for a greater emphasis on even-aged management of the spruce-fir forest type in Maine~ As red spruce (Picea rubens Sarg.), black spruce (Picea mariana (Mill.) B.S.P.), white spruce (Picea glauca (Moench) Voss), and balsam fir (Abies balsamea (L.) Mill.) are the backbone of Maine's forest industry, it is desirable to identify those sites best suited to the growth of these species.

An easily attained and sufficiently accurate method of estimating the relative quality of a particular site is essential to sound forest management. Site index, defined as being the height attained by the dominant stand at an arbitrarily chosen age, commonly 50 years in the northeastern United States, has been the most widely used measure of site quality. In addition to being an easily measured indicator of relative site quality, site index provides a crucial parameter in the estimation of the ultimate capability of forest land to produce wood volume.

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Maine Agricultural and Forest Experiment Station




even-aged stand, formulate base-age, stem analysis data


Forest Management

B802: Base-Age Invariant Polymorphic Site Index Curves for Even-Aged Spruce-Fir Stands in Maine



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