ScienceDirect - Encyclopedia of Ecology : Herbivore-Predator Cycles1

 

Terrestrial herbivores often exhibit complex or cyclic population dynamics. Approximately 30% of surveyed animal species and populations undergo population cycles, with a latitudinal gradient in cycle strength found in many mammal populations. In addition to their regularity, these cycles are often synchronous over large geographic areas. The proximate and ultimate causes of these cycles have been examined in many separate systems using both time-series analyses and large-scale manipulative experiments. Time-series analyses can point to the process order of systems, with lower orders suggesting little or no time lags and higher orders suggesting significant (3 years or longer) lags between drivers and population reactions. Manipulative experiments have generally been unable to stop the cycles entirely, but can delay or lessen some of the population crashes in mammals such as voles and hares. The drivers of the cycles vary among populations, but a major trend is that of trophic interactions between either predators and herbivores or between parasites and herbivores. It is only through a mixture of mathematical analysis and experimental manipulation that we can accurately explain how cycles begin, end, and persist over several cycles.

ScienceDirect - Encyclopedia of Ecology : Herbivore-Predator Cycles1