Characteristic Description
Community contribution* Proportion of a given genus in the community, based on the total number of rodent individuals. Calculated for each rodent genus. See Appendix 1 Text A1 on calculation at location level.
Mean density Mean trapping index, calculated for each rodent genus.
Cycle amplitude Variability of the population abundance around the mean. Calculated using the standard deviation of log-transformed (log +0.01) time-series (i.e. the s-index, (Stenseth and Framstad 1980)). Calculated for each rodent genus.
Peak sharpness Based on skewness of the data, which is defined as \(\gamma_{1}=\mu_{3}/\mu_{2}^{3/2}\)2 and µ3 are the second and third central moments of the time-series). Skewness describes the degree of asymmetry of data. Negative skewness relates to a few observations at very low density, but most near the maximum density (i.e. round cycles), whereas zero skewness relates to symmetric data and positive skewness to most observations at low density and only few at high densities (i.e. sharp cycles) (Turchin et al. 2000). Calculated for each rodent genus.
Peak interval* Mean number of years between population peaks. Calculated based on visual inspection of data, assigning year t as a peak year when a population had a positive growth rate from t-1 and negative to t+1. See Hanski et al. (1991) and Appendix 1 (Text A1). Calculated for the entire rodent community, as different rodent species at the same location usually have synchronous cycles, and at sampling units with little data the signal of a cycle could be missed if evaluated for one species only.