Vascular plant compositional gradients within and between Iowa fens:
Question: What is the nature and relative importance of compositional gradients within- and between fens?
Conclusions: While the principal axis of variation (corresponding to the rich-poor fen gradient) is present largely between sites, the second axis (corresponding to water level) is largely repeated within sites.
What does this mean? The species in nutrient rich areas are different from poor areas, and that's because some species are adapted (evolutionarily) to different environments.