EFFECTS OF POSTDISPERSAL SEED PREDATION ON SPATIAL INEQUALITY AND SIZE VARIABILITY IN AN ANNUAL PLANT, ERODIUM-CICUTARIUM (GERANIACEAE)

Citation
Gd. Harmon et Ne. Stamp, EFFECTS OF POSTDISPERSAL SEED PREDATION ON SPATIAL INEQUALITY AND SIZE VARIABILITY IN AN ANNUAL PLANT, ERODIUM-CICUTARIUM (GERANIACEAE), American journal of botany, 79(3), 1992, pp. 300-305
Citations number
28
Language
INGLESE
art.tipo
Article
Journal title
ISSN journal
0002-9122
Volume
79
Issue
3
Year of publication
1992
Pages
300 - 305
Database
ISI
SICI code
0002-9122(1992)79:3<300:EOPSPO>2.0.ZU;2-M
Abstract
By decreasing seed density, ants introduced into flats of uniformly so wn seeds of Erodium cicutarium (Geraniaceae) created differences in th e neighbor-free area available to individual plants. The changes in sp atial patterns brought about by the ants were greater when a higher pr oportion of seeds was removed but were independent of initial seed den sity. These spatial changes and differences in seed density were exami ned for their effects on plant size and reproduction. Gini values were calculated to determine inequalities. As the inequality in space amon g individual plants increased, the variation in final biomass increase d. The number of individuals reproducing was constant among treatments , and yet seed production per plant was significantly greater for popu lations in which the spatial pattern was influenced by seed predation. The decrease in density and changed spatial pattern, due to previous seed predation, resulted in a few individuals having much more space t han others and consequently producing many more seeds. The increase in reproductive effort per flat was much greater than could be explained by the changing density alone. Our experiment demonstrates that spati al inequality, such as that generated by seed predators, can be more i mportant than density in generating size inequalities in plant populat ions. This result can profoundly alter the competitive interactions be tween plants and determine which plants produce seed for the next gene ration.