Replacement of Ulmus americana L. in a Mature East-Central Indiana Woods

Abstract

In 1926 all trees (.gtoreq. 10.2 cm dbh [diameter at breast height]) were permanently tagged and mapped in a 20.6 ha, mature trace of timber in Randolph County, Indiana. The central 8.5 h were resurveyed in 1976. The relative basal area and relative density of U. americana, American elm, in 1926 were 4.2 and 12.9%, respectively, for an importance value ((relative density + relative basal area) .fwdarw. 2) of 8.6. By 1976, 94.5% (172 individuals) of the tagged U. americana were dead, but 633 individuals were recorded for an importance value of 14.1. Species (and percent of total 440 ingrowth trees .gtoreq. 10 cm dbh) which grew into the gaps created by dead American elm were U. americana (24%). Acer saccharum (15%), Celtis occidentalis (9%), Carya ovata (9%), Aesculus glabra (7%), Fraxinus americana (6%), Fagus grandifolia (4%) and other species (26%). Although Dutch elm disease and elm yellows (phloem necrosis) have killed most American elms that existed in the initial survey, elm density had increased 3-fold by 1976. Early reproductive maturity and shade tolerance has allowed U. americana to persist, although its presence is restricted to smaller diameter individuals.