| This thesis examines ecological heterogeneity induced by geomorphology and hydrology, which are presented independently here as two case studies of macroinvertebrate communities in streams. In the first study, the communities surrounding knickpoints are described, along with knickpoint-induced fluctuations in discharge and bed sediment. The influence of a knickpoint in providing heterogeneous habitat to support biodiversity is discussed, as is the importance of such micro-scale heterogeneity in the face of watershed-scale urbanization effects. In the second study, macroinvertebrate community responses to an experimental drought and rewetting are analyzed. Community alteration along spatial and temporal disturbance gradients is assessed, specifically with regards to changes in community dispersion in ordination space. Shifts in species dominance patterns resulting from decreased prey competition are also described, as is the importance of hydrologic conditions as analogues for available habitat during drought. |
