Suppression and Release during Canopy Recruitment in Acer saccharum

Abstract

Patterns of radial growth were used to reconstruct the history of suppression and release during canopy recruitment of A. saccharum Marsh. in old-growth northern hardwood forests of the Adirondack Mountains of New York [USA]. In a stand that had been selectively logged 60-80 yr ago, only 20% of canopy trees between 20-40 cm DBH had undergone periods of suppression prior to canopy recruitment. In 2 unlogged stands, all of the sampled trees had undergone from 1-5 definable episodes of suppression prior to eventual recruitment at an average age of 110-126 yr. The mean lengths of periods of suppression (22-28 yr in the 2 unlogged stands), combined with the mean numbers of periods of suppression in each core (2.9-3.1/tree) indicate that saplings of A. saccharum responded to canopy openings created by the death of neighboring trees before eventually replacing an individual directly overhead. The ability to withstand suppression appears to be an essential trait for a life history that allows A. saccharum to exploit the relatively short-lived pulses of resources created by small canopy openings.