Ostfeld R S, Canham C D, Pugh S R
Institute of Ecosystem Studies, Millbrook, New York 12545.
Nature. 1993 Nov 18;366(6452):259-61. doi: 10.1038/366259a0.
Considerable controversy exists over the role of density-dependent processes in controlling animal population size. In populations that fluctuate cyclically or erratically, for example many voles and insects, theory predicts that either density-dependence is weak, or that density-dependent responses lag behind density. One key mechanism for lagged density-dependence is a delay in regeneration of food resources following heavy exploitation. Here we show that meadow vole (Microtus pennsylvanicus) populations respond immediately to high density by reducing breeding effort and hence population growth, disproving the hypothesis that density-dependence is weak. In addition, vole populations do not show a delay in growth following marked reduction in plant biomass (their source of food and cover). We conclude that intrinsic density-dependence processes tend to stabilize vole populations, and that cyclic dynamics are not caused by lagged effects of resource exploitation.
关于密度依赖过程在控制动物种群数量方面的作用，存在着相当大的争议。在周期性或无规律波动的种群中，例如许多田鼠和昆虫，理论预测要么密度依赖作用微弱，要么密度依赖反应滞后于密度变化。滞后密度依赖的一个关键机制是在大量消耗后食物资源再生的延迟。在此我们表明，草甸田鼠（Microtus pennsylvanicus）种群会通过降低繁殖努力从而减少种群增长来对高密度立即做出反应，这一结果反驳了密度依赖作用微弱的假说。此外，在植物生物量（它们的食物和掩护来源）显著减少后，田鼠种群的增长并未出现延迟。我们得出结论，内在的密度依赖过程倾向于使田鼠种群稳定，并且周期性动态并非由资源开发的滞后效应所导致。
