N.C. Stenseth, W. Falck, K.-C. Chan, O.N. Bjørnstad, H. Tong, M. O'Donoghue, R. Boonstra, S. Boutin, C.J. Krebs and N.G. Yoccoz: From pattern to process - phase- and density-dependence in the canadian lynx cycle

Proceedings of the National Academy of Science USA (1998) 95:15430-15435


Across the boreal forest of North America, lynx populations undergo 10-year cycles. Analysis of 21 time series from 1821 to the present (1-3) demonstrates that these fluctuations are generated by non-linear processes with regulatory delays. Trophic interactions between lynx and hares cause delayed density-dependent regulation of lynx population growth. The non-linearity, in contrast, appears to arise from phase-dependencies in hunting success by lynx through the cycle. Using a combined approach of empirical, statistical and mathematical modeling (4-9), we highlight how shifts in trophic interactions between the lynx and the hare generate the non-linear process primarily by shifting functional response curves during the increase and the decrease phases.

Key words: statistical modeling, non-linearity, threshold autoregressive modeling, population dynamics