Floral Ecology in Relation to Plant Species Diversity in the Wasatch Mountains of Utah and Idaho

Abstract

An analysis of the relative abundance of the prevalent species in 25 major plant communities of the Wasatch Mountains demonstrates that variation in species diversity is significantly correlated with many floral characteristics. Wind—pollinated flowers decrease in abundance whereas animal—pollinated flowers increase along the diversity gradient. The relationship is statistically significant. Color diversity and species diversity are significantly and positively correlated in open communities bur are unrelated in forest communities. The percent sum frequency of yellow flowers decreases with increasing species diversity whereas blue flowers increase. Also, zygomorphic flowers and flowers in which access to the nectar supply is restricted by morphological barriers are positively correlated with species diversity. It is shown that species with wind—pollinated flowers and zoophilous species having open flowers are significantly better represented in the higher frequency classes than animal—pollinated species whose nectaries are morphologically restricted. The results suggest that many floral characteristics impart a reproductive advantage to species growing in communities of high diversity. That the relationships observed can be predicted with reasonable confidence within a small geographic area implies that the selective forces are local and strong.