Habitat modification is now a widespread phenomenon, impacting landscape structure, biophysical processes, food webs and biodiversity. These changes have trickle-down effects on trophic cascades: predators often become rarer, increasing prey populations, which then subject plants to higher levels of herbivory. How habitat modification mediates this trophic cascade, however, is poorly understood, and this is particularly true for temperate forests. Here we investigate if the strength of trophic cascades, defined as the magnitude of the effect of bird exclusion on leaf damage, varies along a gradient of increasing habitat modification, from forest interior to forest edge to open habitat, through an experimental manipulation of bird exclusion. We found that habitat modification reduces the number of bird observations, with trophic cascades being three times stronger in the forest interior than edge and open habitats. However, there is no corresponding increase in leaf damage with habitat modification in the presence of birds, suggesting that other taxa or factors may mediate leaf damage in modified habitats. Our findings suggest that even though habitat modification disrupts the functions that birds perform in the ecosystem, overall ecosystem function is not dramatically altered, possibly due to the functional redundancy of birds.

现在，栖息地改造已成为一种普遍现象，影响着景观结构，生物物理过程，食物网和生物多样性。这些变化对营养级联有trick滴效应：捕食者通常变得稀少，猎物种群增加，然后使植物遭受更高水平的食草。然而，人们对如何改变栖息地的营养级联反应知之甚少，对于温带森林尤其如此。在这里，我们通过对鸟类排斥的实验性操作，研究了营养级联的强度（定义为鸟类对叶片损害的影响程度）是否沿着不断变化的生境变化梯度变化，从森林内部到森林边缘再到开放生境。 。我们发现栖息地的改变减少了鸟类观测的数量，在森林内部，营养级联比边缘和开放栖息地强三倍。然而，在鸟类存在的情况下，随着生境的改变，叶片的伤害并没有相应增加，这表明其他类群或因素可能介导了改良的栖息地中的叶片伤害。我们的发现表明，即使栖息地的改变破坏了鸟类在生态系统中的功能，但总体生态系统的功能并没有显着改变，这可能是由于鸟类的功能冗余所致。