presented on November 21, 2000. Title: Structure and Development of Old-Growth

The tree species and size structure of9l old-growth forests dominated by Douglas-fir in central western Oregon was characterized using complete inventories of all trees larger than 20cm dbh over a mean area of 17. iha at each site. Douglas-fir accounted for over 75 % of the total average basal area (39.1 of 49.2 m2/ha) at each site. Conventional and multivariate analysis indicated that the non-Douglas-fir component accounted for most of the structural variation between sites. Multivariate analysis characterized six groups based on the similarities and differences among sites in basal area of small (20-50cm dbh), medium (50-100cm dbh), and large (> 100cm dbh) western hemlock, western red cedar, incense-cedar, grand fir, red alder, and bigleaf maple. The hypothesis that large-diameter, old-growth Douglas-fir in central western Oregon developed at low stand densities was supported by patterns of long-term diameter and basal area growth of trees, wide mean within-site age ranges (95 % CI for mean = 134-214yr), and stem and crown characteristics. The diameters of the old-growth trees at ages 100 to 300yr were strongly, positively, and linearly related t