Factors affecting survivorship, growth, and fruit production in a beach population ofXanthium strumarium

摘要

In a beach population ofXanthium strumarium, we assessed the effects of density, seedling emergence date, and soil moisture on seedling survivorship, plant growth, and fruit production. Seedling survival was largely density independent, while growth and fruit production declined significantly with increased density. Delayed seedling emergence resulted in significantly lowered survival but exhibited no significant effects on fruit production. Soil moisture was correlated positively with seedling survival, growth, and fruit production. Blowing sand was noted as an important cause of seedling mortality. Increased survival in areas of high soil moisture apparently resulted because of an absence of blowing sand in these areas. Consistent with a lack of density-dependent mortality, the densityndash;yield relationship for the population had a slope near minus;1 and not minus;3/2. Hierarchy in fruit production among plants was least developed in areas of high plant density.