CONSUMER DRIVEN POLLEN LIMITATION OF SEED PRODUCTION IN MARSH GRASSES

Citation
Md. Bertness et Sw. Shumway, CONSUMER DRIVEN POLLEN LIMITATION OF SEED PRODUCTION IN MARSH GRASSES, American journal of botany, 79(3), 1992, pp. 288-293
Citations number
25
Language
INGLESE
art.tipo
Article
Journal title
ISSN journal
0002-9122
Volume
79
Issue
3
Year of publication
1992
Pages
288 - 293
Database
ISI
SICI code
0002-9122(1992)79:3<288:CDPLOS>2.0.ZU;2-#
Abstract
While flower predators can limit the sexual expression and seed produc tion of salt marsh grasses, the relationship between these two effects of consumers has not been explored. At our study site, predation on S partina patens, Spartina alterniflora, and Distichlis spicata was twic e as high in 1985 (approximately 70% ovule destruction) as in 1986 (ap proximately 35% ovule destruction). In both years consumers destroyed flowers before maturity, reducing sexual expression, and particularly suppressed male sexual expression. Sexual suppression of males was muc h more pronounced in 1985 when flower predation was severe and the see d production of undamaged ovules was dramatically reduced. A number of lines of evidence suggest that predator limitation of male sexual exp ression and pollen supply contributed to low seed output in 1985. 1) U ndamaged ovules of all three grasses protected from consumers but expo sed to ambient windborne pollen set many more seeds in 1986 than in 19 85, suggesting that pollen was more abundant in 1986; 2) Artificial po llinations revealed that marsh grasses are generally pollen-limited an d that pollen limitation at our study site was more severe in 1985 tha n 1986; and 3) Caging stands of marsh grasses generally led to less pr edator damage, increased male densities and seed sets similar to those for hand-pollinated flowers. Our results support the hypothesis that flower predators can indirectly limit seed production by decreasing po llen availability.