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Nonlinear time‐series modeling of vole population fluctuations
Author(s) -
Turchin Peter
Publication year - 1996
Publication title -
population ecology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.819
H-Index - 59
eISSN - 1438-390X
pISSN - 1438-3896
DOI - 10.1007/bf02515720
Subject(s) - predictability , lyapunov exponent , population cycle , vole , population , nonlinear system , statistical physics , series (stratigraphy) , chaotic , econometrics , population model , biology , ecology , mathematics , physics , statistics , computer science , demography , artificial intelligence , paleontology , quantum mechanics , sociology
A central goal of population ecology is to understand and predict fluctuations in population numbers. Until recently, much of the debate focused on the issue of population regulation by density‐dependent factors. In this paper, I describe an approach to nonlinear modeling of time‐series data that is designed to go beyond this question by investigating the possibility of complex population dynamics, characterized by lags in regulation and periodic or chaotic oscillations. The questions motivating this approach are: what are relative contributions of endogenous vs. exogenous components of dynamics? Is the irregular component in fluctuations entirely due to exogenous noise, or do nonlinearities contribute to it, too? I describe the philosophy and the technical details of the nonlinear modeling approach, and then apply it to a collection of time‐series data on vole population fluctuations in northern Europe. The results suggest that population dynamics of European voles undergo a latitudinal shift from stability to chaos. Dynamics in northern Fennoscandia are characterized by positive Lyapunov exponent estimates, and a high degree of short‐term (one year ahead) predictability, suggesting a strong endogenous component. In more southerly populations estimated Lyapunov exponents are negative, and there is no one‐step ahead predictability, suggesting that fluctuations are driven by exogenous factors.