Tree establishment in canopy openings in mature Douglas-fir forests

Biological diversity in coastal Douglas-fir forests is strongly as-sociated with forest age and the arrangement of older forests on thelandscape. Many plant and animal species first appear late in suc-cession as these forests develop the multi-layered and patchy can-opies characteristic of old growth. It is presently unknown whetherthis influx of species is in response to a general decline in thedominance of the large Douglas-fir (Pseudotsuga menziesii), or to dis-crete openings in the forest canopy (termed "canopy gaps") causedby the death of large trees. The answer is important for maintainingecological diversity in managed forests and reserves.