The effect of food web structure on the population dynamics of pitcher plant microfauna

My objective was to quantify how local and regional dynamics affect the population dynamics of pitcher plant microfauna. I studied (a) factors affecting arthropod community assembly, (b) how top-down and bottom-up factors affected the local population dynamics of microfauna, (c) the effects of community structure and growth rates on population synchrony of one microfaunal taxon. I showed that the assembly of the arthropod community was an important determinant of local and regional dynamics of the aquatic microfauna.; I found that both fine- and meso-scale factors affected the assembly of the arthropod community. All three taxa responded to the fine-scale factors, leaf length, and capture rate, but the strength of the responses frequently depended on plant density—a meso-scale factor. Midges, but not mosquitoes or mites, responded directly to plant density.; The abundance and dynamics of the microfauna community is potentially affected by both pitcher plant arthropods and the resources captured by the leaf. Ecological theory suggests that top-down and bottom-up effects can be stabilizing or destabilizing, depending on community structure. Predation tended to decrease and destabilize microfaunal populations, leading to higher temporal variability and lower persistence times. Bottom-up effects varied with taxon and depended on the manner in which resource availability was increased. Top-down effects tended to be destabilizing, but the influence of bottom-up factors on stability depended on patterns of midge abundance.; Community structure and growth rates can affect population synchrony, which, in turn affects regional persistence. Recent modelling studies predict that high population growth rates will decrease population synchrony by reducing the synchronizing effect of dispersal. I found that growth rates, and high mosquito and midge densities did lower population synchrony. Synchrony had no effect on local stability, but there was some evidence that greater synchrony decreased regional stability.