Density dependence in ungulates: a review of causes, and concepts with some clarifications

作者：Bowyer R Terry^*; Bleich Vernon C; Stewart Kelley M; Whiting Jericho C; Monteith Kevin L

来源：California Fish and Game, 2014, 100(3): 550-572.

• additive mortality
• compensatory mortality
• demographics
• density dependence
• density independence
• forcing
• life-history characteristics
• limitation
• predation
• regulation
• ungulates

Understanding population dynamics of ungulates is not conceptually simple, in part, because there are many counterintuitive processes. We attempt to disentangle important concepts, including density dependence, density independence, limitation, regulation, compensatory and additive mortality, and top-down versus bottom-up forcing by examining how those ideas are related to the carrying capacity (K) of the environment. We contend that the K-selected, life-history characteristics of ungulates account for major components of their population dynamics. Those density-dependent attributes of ungulates require different management strategies than for species with attributes that are influenced primarily by density-independent processes. We offer a conceptual framework to help explain how density-dependent processes can be confused with those that are density-independent. We also discuss why regulation is the correct term for describing demographics of ungulates when limiting factors have density-dependent feedbacks. We emphasize that density per se is not valuable for understanding density dependence rather, the population size relative to K is the critical factor. Comparisons among populations or within a population through time based on density alone are flawed, because K is not necessarily constant and can result in misleading results and conclusions. Whether mortality is compensatory or additive is a function of where the population is in relation to K, which is critically important when determining if and when predator control is biologically justified. We provide a model based on life-history characteristics to help parameterize where the population is in relation to K, and discuss a new nutritional model (nutritional carry capacity; NCC) for determining the relative degree of compensatory or additive mortality and the proximity of a population to its food supply.

• 出版日期2014