You are not currently logged in.
Access your personal account or get JSTOR access through your library or other institution:
If You Use a Screen ReaderThis content is available through Read Online (Free) program, which relies on page scans. Since scans are not currently available to screen readers, please contact JSTOR User Support for access. We'll provide a PDF copy for your screen reader.
Since scans are not currently available to screen readers, please contact JSTOR User Support for access. We'll provide a PDF copy for your screen reader.
Preview not available
Our approach is twofold. First, with 1964-1983 data on red squirrel (Sciurus vulgaris) in 11 provinces in Finland we show that population fluctuations in different parts of the country are largely synchronous. Second, using two differing model types for producing the dynamics of populations we set up to examine the synchronizing effect of an extrinsic disturbing factor, the Moran effect. We show that in a spatially structured population system a randomly occurring stochastic perturbation reducing reproduction success is indeed capable of synchronizing subpopulations. The synchronizing effect is achievable with a wide range of probabilities of occurrence and strengths. However, when the Moran effect occurs in most years its synchronizing power wanes, despite the strength of the effect. Allowing regionality in the variance of the strength of the Moran effect reduces the synchronizing capacity of the perturbation. The Moran effect is also capable of producing a wide range of population dynamics from very simple premises.
Oikos © 1997 Nordic Society Oikos