Biological Invasion of the Drew University (New Jersey) Forest Preserve by Norway Maple (Acer platanoides L.)

WEBB, S. L. (Biology Department, Drew University, Madison, NJ 07940 USA) AND C. K. KAUNZINGER. Biological invasion of the Drew University (New Jersey) Forest Preserve by Norway maple (Acer platanoides L.). Bull. Torrey Bot. Club 120: 343-349. 1993.-The invasiveness of nonnative Acer platanoides in an isolated New Jersey Fagus grandifolia-Quercus spp.-Acer saccharum forest preserve was investigated by comparing size and age profiles of the exotic species with those of other tree populations present. Increment cores show that Acer platanoides was present by 1915 and is now plentiful in all younger age classes. Acer platanoides is the second most abundant canopy species (17.2% of stems), outnumbered only by Fagus grandifolia (41%), and more numerous than either Acer saccharum (9.4%) or Quercus spp. (11.7%). Because of its relatively recent arrival, Acer platanoides ranks in dominance (8.2% relative basal area) below Quercus velutina (29.1%), Fagus grandifolia (26.1%), and Quercus alba (12.1%), but above Acer saccharum (1.9%). Acer platanoides seems likely to increase in importance in the future, because its abundant (> 2000/ha) shade-tolerant seedlings and saplings comprise 59% of all small (DBH < 5 cm) woody stems, over twice the amount of Fagus grandifolia reproduction (23.1%) and five times the Acer saccharum reproduction (10.5%). To maintain or restore examples of relatively natural forest communities in this region, it may be necessary to restrict horticultural plantings and remove mature individuals of this popular tree in the vicinity of nature preserves.