PARENT SESSION
Monday, August 7, 5:00-6:30 pm
Poster Session 5 - Landscape and ecosystem ecology
Exhibit Hall, Ballroom Level, Cook Convention Center
The impacts of area, isolation, and dissimilarity on coexistence along a productivity gradient.
Li, Wei*,1, Stevens, M. Henry1, 1 Miami University, Oxford, OH
ABSTRACT- Evidence shows that the general forms of the relation between productivity and richness are highly variable. Several recent reviews indicate that the spatial extent, or area, of communities contributes to this variability. A hump-shaped pattern is frequently observed in small areas, whereas a positive pattern is common in large areas. Here we provide the first experimental test of the effect of area, together with the physical isolation of communities, on the species richness-productivity relationship. Replicate microcosms were assembled consisting of a small number of algae and protozoa species, and a diverse bacterial flora. Culture medium was diluted to make seven levels of productivity. Area was varied in two ways. First, culture dishes of different sizes varied area without substantially influencing isolation among locales, i.e. different locations within a dish. Second, replicate dishes of the same size and productivity level were pooled to create larger areas in which some locales were completely isolated from each other. Results showed that among locales without isolation, the productivity-richness relationship of these microbial species varied little with area. However, increasing area with isolation among locales caused the productivity-richness relation to flatten, which resulted from a negative dissimilarity-productivity relation. Thus the relation between species richness and productivity is scale-dependent only when different scales have different levels of isolation. Further, this scale dependence results from variation in dissimilarity, the potential explaining for the variable productivity-richness patterns at different scales with different levels of isolation.
Key words: isolation, area, dissimilarity