Dispersal Characteristics of Two Native and Two Nonnative Fleshy-Fruited Sympatric Shrubs

Published:

June 2014

Author

Laura J. McCall

Additional Authors

Jeffrey L. Walck

ABSTRACT Aspects of the dispersal characteristics of two nonnative shrubs, Elaeagnus umbellata and Ligustrum sinense, were compared with those of two native shrubs, Cornus amomum and Frangula caroliniana, to identify factors that contribute to successful invasion of the nonnative species. For each species, the following aspects were examined: shrub abundance, physical characteristics and nutritional values of fruits, arrangement of fruits along the stem and number of fruits per branch, phenology of fruit maturation and foliage coloration, and animal interactions. The two native shrubs and E. umbellata were similar in abundance, but L. sinense was significantly more abundant than the others. Cornus amomum and F. caroliniana present bicolored displays of fruits that are rapidly dispersed during autumn avian migration. Elaeagnus umbellata produces moisture- and protein-rich fruits during summer that are also rapidly removed. In contrast, L. sinense produces high numbers of fruits in late autumn that remain available to frugivores throughout the winter. The large quantities and prolonged availability of L. sinense fruits enable the dispersal of this shrub by a diverse array of frugivores and contribute at least partially to its successful invasion of new habitat and its observed abundance.

Keywords

Bicolored display, exotic species, fruit nutrition, fruit phenology, seed dispersal, seed production.