VINE MAPLE CLONE GROWTH AND REPRODUCTION IN MANAGED AND UNMANAGED COASTAL OREGON DOUGLAS-FIR FORESTS

Vine maple (Acer circinatum Pursh.) clone development, expansion, and regeneration by seedling establishment were studied in 5-240 yr old ma naged and unmanaged Douglas-fir (Pseudotsuga menziesii (Mirb.) France) stands in coastal Oregon. Stem length, number of stems, and crown are a were all significantly (P less than or equal to 0.01) related to sta nd age, and clone development was most rapid during the first 50 yr of stand development. Following clear-cutting, clones were clumps of 1-3 m long upright stems. Fifty years after disturbance, clones consisted of 5-15 drooping aerial stems > 10 m long and basal sprouts 1-2 m lon g; some stems had been pinned to the forest floor by fallen trees or b ranches and had layered. In stands > 120 yr in age, clones were often quite complex, composed of several decumbent stems each of which conne cted the ramets of 1-10 new aerial stems. Vine maple clone expansion o ccurs by the layering of long aerial stems. Over 95% of the layered st ems we observed had been pinned to the forest floor by fallen debris. Unsevered stems that we artificially pinned to the forest floor initia ted roots within 1 yr Thinning may favor clonal expansion because fall en slash from thinning often causes entire clones to layer, not just i ndividual stems. Clonal vine maple seed production and seedling establ ishment occurred in all stages of stand development except dense, youn g stands following crown closure. There were more seedlings in thinned stands than in unthinned stands and in unburned clearcuts than in bur ned clearcuts.