Community and Macroecology Group, Abteilung Ökologie, Institut für Zoologie, Johannes Gutenberg-Universität, 55099, Mainz, Germany.
Oecologia. 2012 Feb;168(2):425-37. doi: 10.1007/s00442-011-2090-1. Epub 2011 Aug 5.
Land-use intensification is a major cause for the decline in species diversity in human-modified landscapes. The loss of functionally important species can reduce a variety of ecosystem functions, such as pollination and seed dispersal, but the intricate relationships between land-use intensity, biodiversity and ecosystem functioning are still contentious. Along a gradient from forest to intensively used farmland, we quantified bee species richness, visitation rates of bees and pollination success of wild cherry trees (Prunus avium). We analysed the effects of structural habitat diversity at a local scale and of the proportion of suitable habitat around each tree at a landscape scale. We compared these findings with those from previous studies of seed-dispersing birds and mammals in the same model system and along the same land-use gradient. Bee species richness and visitation rates were found to be highest in structurally simple habitats, whereas bird species richness--but not their visitation rates--were highest in structurally complex habitats. Mammal visitation rates were only influenced at the landscape scale. These results show that different functional groups of animals respond idiosyncratically to gradients in habitat and landscape structure. Despite strong effects on bees and birds, pollination success and bird seed removal did not differ along the land-use gradient at both spatial scales. These results suggest that mobile organisms, such as bees and birds, move over long distances in intensively used landscapes and thereby buffer pollination and seed-dispersal interactions. We conclude that measures of species richness and interaction frequencies are not sufficient on their own to understand the ultimate consequences of land-use intensification on ecosystem functioning.
土地利用集约化是人类改造景观中物种多样性下降的主要原因。功能重要物种的丧失会降低多种生态系统功能，如传粉和种子散布，但土地利用强度、生物多样性和生态系统功能之间的复杂关系仍存在争议。我们沿着从森林到集约化农田的梯度，量化了蜜蜂物种丰富度、蜜蜂访问率和野生樱桃树（Prunus avium）的授粉成功率。我们分析了局部尺度结构生境多样性的影响，以及每棵树周围适宜生境比例的景观尺度影响。我们将这些发现与同一模型系统和沿同一生境梯度的种子散布鸟类和哺乳动物的先前研究结果进行了比较。结果表明，蜜蜂物种丰富度和访问率在结构简单的生境中最高，而鸟类物种丰富度——而不是它们的访问率——在结构复杂的生境中最高。哺乳动物的访问率仅在景观尺度上受到影响。这些结果表明，不同功能类群的动物对生境和景观结构梯度的反应是特殊的。尽管对蜜蜂和鸟类有强烈影响，但授粉成功率和鸟类种子去除率在两个空间尺度上都没有沿着土地利用梯度而有所不同。这些结果表明，在集约化景观中，移动能力强的生物，如蜜蜂和鸟类，可以远距离移动，从而缓冲授粉和种子散布相互作用。我们得出结论，仅通过物种丰富度和相互作用频率的测量不足以理解土地利用集约化对生态系统功能的最终影响。
