Estimating gap origin probabilities for canopy trees

A method is presented for estimating the probability that existing canopy trees were growing in gaps during the sapling stage, given observed mean 5yr radial growth rates starting at the point where the trees were 4cm dbh. The method is illustrated with data from sugar maple Acer saccharum and eastern hemlock Tsuga canadensis in mature and old northern hardwood forests of W Upper Michigan. The proportion of canopy trees that had been growing in gaps during the sapling stage ranged from 35-67% in different stands, a range suggesting the adaptability of these 2 late-successional, shade-tolerant species to a variety of stand microenvironments. -from Authors