Old field Vegetation Height and the Dispersal Pattern of Bird-Disseminated Woody Plants

Abstract

McDONNELL, M. J. (Department of Biological Sciences, Rutgers University, P.O. Box 1059, Piscataway, NJ 08854). Old field vegetation height and the dispersal pattern of bird-disseminated woody plants. Bull. Torrey Bot. Club 113:6-11. 1986.-To determine the influence of old-field woody vegetation height on the dispersal pattern of bird-disseminated plants, white ash (Fraxinus americana) saplings, of similar size and shape, were cut and placed on stakes at various heights (0.5-3.0 m) in a 1 ha field in central New Jersey. From August 9 to December 30, 1981 a total of 1247 seeds was collected from under the saplings in a total trap surface of 36 m2. The most abundant seeds collected were Toxicodendron radicans, Rosa multiflora, Phytolacca americana, and Juniperus virginiana. Seed input under saplings increased proportionally with sapling height. The tallest height class (3 m) received the greatest seed input, while the shortest height class (0.5 m) received no seed input. Saplings became attractive perches and served as recruitment foci for bird-dispersed seeds when they projected over the existing matrix of herbaceous vegetation. Existing old-field vegetation influences the effectiveness of both living (e.g., woody plants) and non-living (e.g., rocks, fence posts, etc.) structures as recruitment foci for bird-disseminated plants.