Ecological mechanisms maintaining the demographic and spatial structure of small mammal populations

Abstract

441 The dynamics of abundance is an integrated indi� cator of its state and reflects the outcome of its inter� action with the environment. The breeding cycles of animals are timed to the spring–summer season, which may be regarded as a major factor responsible for the delayed response of a population to changes in environmental conditions. This delay, the high repro� ductive potential of small mammals, density depen� dent regulation of animal breeding and mortality, the amount and quality of food resources, and many other factors may cause changes in the demographic and spatial structure of the population (Shilov, 1967; Shvarts, 1980; Bol’shakov and Kubantsev, 1984; Bol’shakov et al., 1986; Krebs, 1996; Zhigalski, 2002, 2012; Lukyanova, 2013). The question concerning the causes underlying the variability of population phenomena is far from being resolved. The growing amount of data based on long� term observations on mammals living in different geo� graphic zones makes it increasingly clear that the level of variation in population processes is determined not only by the geographic component: it also depends on the quality and holding capacity of the environment, its heterogeneity, productivity of plant communities, the state of the population in the current and previous moments of time, the hierarchical status of species in the community, and other factors (Shilov, 1967; Shvarts, 1980; Zhigalski, 1992; Krebs, 1996; Ivanter and Zhigalski, 2000; Zhigalski, 2002, 2012). The significance and relevance of the materials presented here consist in evaluation of the roles of intrapopulation and external factors in the formation of mechanisms for maintaining the demographic and spatial structure of small mammal populations in the center and at the periphery of the range.