Old growth and forest dynamics in the Douglas-fir region of western Oregon and Washington

Changes in the structure and function of Douglas-fir forests as theydevelop from young stands to old growth arc examined. Old-growth Douglas-fir/western hemlock forests arc a long-lived phase of a potentially very long successionalsequence. After disturbance, some ecosystem attributes, such as leaf area and waterquality, recover relatively quickly, while others, such as live and dead woody structures,which are important for wildlife, return to predisturbance maxima and toward a relativesteady state only after four or five centuries. The gradual and variable nature ofsuccession and stand development make the task of precisely defining old growthdifficult. We propose an index of "old-growthness" or structural diversity that may bea useful tool in maintaining and managing successional diversity in forest landscapes.