PARENT SESSION
Poster Session 2: Forest Ecology
Monday, August 8, 5:00 PM - 6:30 PM, Exhibit Hall 220 A-E, Level 2, Palais des congrès de Montréal
Spatial distribution of trees in northern hardwoods after selection system silviculture and diameter-limit cutting.
Bohn, Kimberly*,1, Yanai, Ruth2, Nyland, Ralph2, 1 kkbohn@att.net, Syracuse, NY2 SUNY, College of Environmental Science and Forestry, Syracuse, NY
ABSTRACT- The spatial arrangement of trees in unmanaged stands changes through time from aggregated or random patterns during the regeneration phase to more uniform distributions after the self-thinning phase. In uneven-aged, old-growth stands the younger age classes may exhibit this same change as they mature, though with more complexity because of the interaction among age classes. Harvesting regimes in uneven-aged stands can alter the development of the younger age classes if it severely affects the spatial structure of residual trees. We simulated and evaluated spatial structure of residual trees on ten 0.8 ha stem maps undergoing selection system and diameter-limit cutting over three cutting cycles. We used the Ripley's K statistic to evaluate point patterns of different size classes, since age and size are highly correlated in northern hardwoods. After simulated selection system cutting, larger sawtimber-sized trees became significantly more uniform in spacing. Medium, pole-sized trees showed a tendency towards uniformity by the 2nd cutting treatment, though the results were not significantly different from a random distribution. On the other hand, simulated diameter-limit cutting led to more random distributions of the residual sawtimber and significant aggregation developed in the poles after the 2nd cutting treatment. Harvesting with selection system silviculture appears well suited to maintaining spatial patterns similar to those of undisturbed forests, though it may speed the process by which younger trees move from aggregated to uniform conditions. It is also a beneficial treatment where uniformity of ecological conditions (i.e. light, vertical structure, habitat) is desired. On the other hand, diameter-limit cutting considerably altered the spatial interactions both within and between age classes. It can induce more competition between younger age classes and possibly lead to greater mortality.
Key words: northern hardwoods, spatial pattern, Ripley's K