2010 Elsevier, Inc. Chapter 22 Complex Community Interactions Dodds & Whiles 2010 Elsevier, Inc. FIGURE 22.1 Mt. St. Helens in Washington State erupted and drastically altered the community of Spirit Lake (foreground). This led to documentation of an unusual case of primary succession. (Photograph courtesy of the US Geological Survey, Lynn Topinka). 2010 Elsevier, Inc. FIGURE 22.2 Relationship between macroinvertebrate species richness (A), Shannon diversity (B), and harshness index in Kings Creek, Kansas. The harshness index is a score based on time since flood or drought, intensity of last flood or drought, and the distance from sources of new colonists. A higher index indicates a harsher habitat. The two points on the left are from permanent sites; the rest are from intermittent sites. Both lines are statistically significant (p, 0.05). (Data from Fritz and Dodds, 2005). 2010 Elsevier, Inc. FIGURE 22.3 A hypothetical successional sequence in the epilimnion of a temperate lake with summer stratification. 2010 Elsevier, Inc. FIGURE 22.4 Numbers of larval fishes in a small eutrophic lake during a summer successional sequence. (Redrawn from Amundrud et al., 1974). 2010 Elsevier, Inc. FIGURE 22.5 A hypothetical seasonal successional sequence in a small temperate stream in a deciduous forest. 2010 Elsevier, Inc. FIGURE 22.6 A successional sequence of algal groups in a desert stream following a flood event. (Reproduced with permission from Fisher and Grimm, 1991). 2010 Elsevier, Inc. FIGURE 22.7 Interactions of fish and tufted ducks in a small English lake. Fish were removed in 1987 and Peak densities of chironomid midge larvae (A), snails (B), and macrophytes (C), and number of duck broods (D) all changed. Fish were added to the enclosures in 1990, and midge and snail densities are reported from inside the enclosures, demonstrating that fish were able to lower both populations. The ? in panel C means not reported. (Data from Giles, 1994). 2010 Elsevier, Inc. FIGURE 22.8 The food web of Little Rock Lake as described by Martinez (1991). Producers are on the bottom ring, consumers above. Species are indicated by the balls, and the sticks connecting the balls indicate which species below are being eaten. Note some of the consumers have loops to themselves representing cannibalism. (Image produced with FoodWeb3D, written by R.J. Williams and provided by the Pacific Ecoinformatics and Computational Ecology Lab ;Yoon et al., 2004).