Department of Entomology, The Hebrew University of Jerusalem, P.O. Box 12, Rehovot 76100, Israel.
Ecol Appl. 2012 Jul;22(5):1535-46. doi: 10.1890/11-1299.1.
Human activity causes abrupt changes in resource availability across the landscape. In order to persist in human-altered landscapes organisms need to shift their habitat use accordingly. Little is known about the mechanisms by which whole communities persist in human-altered landscapes, including the role of complementary habitat use. We define complementary habitat use as the use of different habitats at different times by the same group of species during the course of their activity period. We hypothesize that complementary habitat use is a mechanism through which native bee species persist in human-altered landscapes. To test this idea, we studied wild bee communities in agro-natural landscapes and explored their community-level patterns of habitat and resource use over space and time. The study was conducted in six agro-natural landscapes in the eastern United States, each containing three main bee habitat types (natural habitat, agricultural fields, and old fields). Each of the three habitats exhibited a unique seasonal pattern in amount, diversity, and composition of floral resources, and together they created phenological complementarity in foraging resources for bees. Individual bee species as well as the bee community responded to these spatiotemporal patterns in floral availability and exhibited a parallel pattern of complementary habitat use. The majority of wild bee species, including all the main crop visitors, used fallow areas within crops early in the season, shifted to crops in mid-season, and used old-field habitats later in the season. The natural-forest habitat supported very limited number of bees, mostly visitors of non-crop plants. Old fields are thus an important feature in these arable landscapes for maintaining crop pollination services. Our study provides a detailed examination of how shifts in habitat and resource use may enable bees to persist in highly dynamic agro-natural landscapes, and points to the need for a broad cross-habitat perspective in managing these landscapes.
人类活动会导致景观中资源可用性的突然变化。为了在人为改变的景观中持续存在，生物需要相应地改变它们的栖息地利用方式。人们对整个群落如何在人为改变的景观中持续存在的机制知之甚少，包括互补栖息地利用的作用。我们将互补栖息地利用定义为同一组物种在其活动期间不同时间使用不同栖息地。我们假设互补栖息地利用是本地蜜蜂物种在人为改变的景观中持续存在的一种机制。为了验证这一观点，我们研究了农业自然景观中的野生蜜蜂群落，并探索了它们在空间和时间上对栖息地和资源利用的群落水平模式。该研究在美国东部的六个农业自然景观中进行，每个景观包含三种主要的蜜蜂栖息地类型（自然栖息地、农田和旧田地）。这三种栖息地在花卉资源的数量、多样性和组成方面都表现出独特的季节性模式，它们共同为蜜蜂创造了觅食资源的物候互补性。个体蜜蜂物种以及蜜蜂群落对这些花卉可利用性的时空模式做出了反应，并表现出互补栖息地利用的平行模式。大多数野生蜜蜂物种，包括所有主要的作物传粉者，在季节早期利用作物中的休耕地，在中期转向作物，后期利用旧田地栖息地。自然森林栖息地仅支持非常有限数量的蜜蜂，主要是对非作物植物的访问者。因此，旧田地是这些耕地景观中维持作物授粉服务的重要特征。我们的研究详细考察了栖息地和资源利用的转变如何使蜜蜂能够在高度动态的农业自然景观中持续存在，并指出需要从广泛的跨栖息地角度来管理这些景观。
