了解陆地野生动植物群落的营养级联是一项重大挑战,因为这些系统很难正确采样。我们展示了非随机抽样的传统如何在教科书系统(黄石国家公园)中混淆了这种理解,在该系统中,食肉动物[犬狼疮(狼)]的恢复与营养级联有关,涉及草食动物[Cervuscanadensis(麋鹿)]行为的变化和密度促进植物再生。长期数据表明,与随机抽样相比,仅对最高的幼小植物进行抽样,从而高估了林木白杨(Populustremuloides)的再生4-7倍,因为它偏爱比麋鹿和被忽视的非再生白杨的首选浏览高度高的植物。随机抽样描述了营养级联,但它比非随机抽样描述的弱。我们的发现强调了基本采样原则(例如随机化)对于准确理解陆地野生动物系统中的营养级联至关重要。
Understanding trophic cascades in terrestrial wildlife communities is a major challenge because these systems are difficult to sample properly. We show how a tradition of non-random sampling has confounded this understanding in a textbook system (Yellowstone National Park) where carnivore [Canis lupus (wolf)] recovery is associated with a trophic cascade involving changes in herbivore [Cervus canadensis (elk)] behaviour and density that promote plant regeneration. Long-term data indicate a practice of sampling only the tallest young plants overestimated regeneration of overstory aspen (Populus tremuloides) by a factor of 4-7 compared to random sampling because it favoured plants taller than the preferred browsing height of elk and overlooked non-regenerating aspen stands. Random sampling described a trophic cascade, but it was weaker than the one that non-random sampling described. Our findings highlight the critical importance of basic sampling principles (e.g. randomisation) for achieving an accurate understanding of trophic cascades in terrestrial wildlife systems.