Byrnes Jarrett, Stachowicz John J, Hultgren Kristin M, Randall Hughes A, Olyarnik Suzanne V, Thornber Carol S
Ecol Lett. 2006 Jan;9(1):61-71. doi: 10.1111/j.1461-0248.2005.00842.x.
Although human-mediated extinctions disproportionately affect higher trophic levels, the ecosystem consequences of declining diversity are best known for plants and herbivores. We combined field surveys and experimental manipulations to examine the consequences of changing predator diversity for trophic cascades in kelp forests. In field surveys we found that predator diversity was negatively correlated with herbivore abundance and positively correlated with kelp abundance. To assess whether this relationship was causal, we manipulated predator richness in kelp mesocosms, and found that decreasing predator richness increased herbivore grazing, leading to a decrease in the biomass of the giant kelp Macrocystis. The presence of different predators caused different herbivores to alter their behaviour by reducing grazing, such that total grazing was lowest at highest predator diversity. Our results suggest that declining predator diversity can have cascading effects on community structure by reducing the abundance of key habitat-providing species.
尽管人类介导的物种灭绝对较高营养级的影响尤为严重，但生物多样性下降对生态系统的影响在植物和食草动物方面最为人所知。我们结合了实地调查和实验操作，以研究捕食者多样性变化对海带森林营养级联的影响。在实地调查中，我们发现捕食者多样性与食草动物数量呈负相关，与海带数量呈正相关。为了评估这种关系是否具有因果性，我们在海带中型生态系统中操纵了捕食者丰富度，发现捕食者丰富度的降低增加了食草动物的啃食，导致巨型海带巨藻的生物量减少。不同捕食者的存在会使不同的食草动物通过减少啃食来改变其行为，从而使总啃食量在捕食者多样性最高时最低。我们的结果表明，捕食者多样性的下降可能会通过减少关键栖息地提供物种的数量，对群落结构产生级联效应。
