A beaver creating a wetland leads to species replacements: figure 16. 4 spectrum of disturbance how much biomass is removed and how often it is removed can influence the amount of disturbance that occurs and the type of succession that is possible afterward. Two types of succession differ in their initial stage: through the process of occurs after a: primary succession involves the colonization of habitats devoid of like (volcanic rock) doesn"t happen too often, secondary succession involves reestablishment of a community in which some, but not all, organisms have been destroyed. The sequence of species facilitations leads to a climax community: tolerance model: also assumes the earliest species modify the environment, but in neutral ways that neither benefit nor inhibit later species, inhibition model: assumes early species modify conditions in negative ways that hinder later successional species, figure 16. 8 the three models on page 350.