Growth of ponderosa pine thinned to different stocking levels in central Oregon: 30-year results.

The levels-of-growing-stock (LOGS) study at Lookout Mountain in central Ore gon is one of six studies established in even-aged, pole-sized ponderosa pi ne (Pinus ponderosa Dougl. ex. Laws) stands as part of a westwide investiga tion (Myers 1967, Oliver and Edminster 1988). Two of these studies are in t he Black Hills of South Dakota, two are in Oregon (Barrett 1983, Cochran an d Barrett 1995), one is in northern Arizona (Ronco and others 1985), and on e is on the west slope of the Sierra Nevada in California (Oliver 1979). Th e objective is to compare cumulative wood production, tree size development , and growth-growing stock relations under several different thinning regim es. The Lookout Mountain study is in a naturally regenerated, 1,000-acre stand in central Oregon, in the Pringle Falls Experimental Forest, Deschutes Nati onal Forest. These 30-year results include six measurement periods, each ha ving five growing seasons. Results are directly applicable only to this sta nd, but they provide useful information about managing other ponderosa pine stands on similar sites.