Gap dynamics of old-growth eastern forests: management implications

Runkle, James

How trees die in time and space determines many aspects of forests. Some sites are characterized by infrequent, large-scale disturbances that give rise to predominantly even-aged forests. In other forests, most trees die singly or in small groups, forming what have been termed gaps. Whether large-scale or small-scale disturbances predominate in a given forest has important management implications, both for interpreting annual changes and for manipulating the forest to best match natural processes. This paper focuses on old-growth forests in which small-scale disturbances predominate. Gaps provide the light and soil resources that saplings require to grow and eventually reach the canopy. The exact effects of a particular gap depend upon such factors as the size of the area affected(determined in part by the number and sizes of dead trees involved) and the state of the understory at the time of gap formation. Gaps typical of old-growth forests cannot be mimicked precisely in a young forest, with its smaller crowns and different understory. Creating openings of naturally observed sizes and at natural disturbance rates may approximate old-growth conditions. Old-growth forests also contain a relatively large quantity of dead wood. Many trees die and remain standing for years, fulfilling an important function as wildlife habitat Fallen trees also serve as germination sites for several plant species.There is greater potential for management of this resource than there is for gap creation.Nest boxes, dead logs, and even snags can be added to forests. Management actions to mimic gap and snag dynamics cannot replace all functions of an old-growth forest but may allow certain species and processes to establish at a site several decades earlier than they would by natural changes.

Gap dynamics of old-growth eastern forests: management implications

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