作者: Birger Hornfeldt
DOI: 10.2307/1941735
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摘要: Largely synchronous population fluctuations of Clethrionomys glareolus, C. rufocanus, and Microtus agrestis were monitored by snap-trapping in spring autumn 1971-1988 a strongly seasonal environment near Umea, northern Sweden. All species cyclic the sense that they showed fairly regular (3-4 yr) fluctuations, but amplitudes (nma,/nmin) varied, averaging - 200-fold each species. This conclusion was supported autocorrelation spectral analysis, fitting time series data to model for phase-forgetting cycles. By contrast, did not conform phase-remem- bering cycles (with fixed period amplitude). The transition between cycles, i.e., from low increase phase, characterized distinct shift rate change numbers high or markedly higher values both summer winter. Generally, declined continuously phase through cycle. Moreover, there similar decrease winter, although (mainly rufocanus M. agrestis) first frequently increased early Rate delayed density dependent all as revealed negative correlations with previous winter changes, respectively. These new findings dependence (DDD) support suggestion vole are generated time-lag mechanism. Possible mechanisms DDD discussed. Regression analyses different voles suggest that, besides strong on density, also affected current seed supply (in glareolus) and/or weather variables (temperature precipi- tation sums) may have quantity quality food.