Comparative dynamics of small mammal populations in treefall gaps and surrounding understorey within Amazonian rainforest
Comparative dynamics of small mammal populations in treefall gaps and surrounding understorey within Amazonian rainforest
复制标题
DOI：
10.1111/j.0030-1299.2004.12864.x
复制
发表时间：
2004-07-01
期刊：
影响因子：
3.4
通讯作者：
Nichols, JD
中科院分区：
文献类型：
--
作者：
Beck, H;Gaines, MS;Nichols, JD
食物资源可用性的变化会对栖息地选择和种群动态产生深远影响。先前的研究报告称，树木落差处的食物资源可用性和果实清除率高于林下植被。因此，间隙被认为是新热带食果鸟类的“关键栖息地”。在这里，我们测试这个预测是否也适用于陆地小型哺乳动物。在亚马逊地区，我们量化了 11 个树木间隙和配对的林下栖息地的食物资源可用性，并使用喂养实验来测试两种常见的陆生啮齿动物（Oryzomys megacephalus 和 Proechimys spp.）是否会感知栖息地之间的差异。我们在 11 个间隙和林下地点圈养了小型哺乳动物两年，并比较了这两种啮齿类动物在间隙和林下以及季节（雨季和干旱）的丰度、适应性成分（生存和人均补充量）以及分布情况。我们的数据表明栖息地之间的资源可用性和消耗率没有差异。树木间隙可能代表了稻鼠的一个汇栖息地，那里个体的适应性较低，显然是因为栖息地特定的蚂蚁在生命早期阶段的捕食，而不是在下层，即源栖息地。相反，间隙可能是原鼩鼠的源栖息地，那里的个体比下层的水槽栖息地具有更高的适应度。我们的结果表明，在热带间隙林下景观中存在源汇动态，其中两种啮齿动物对栖息地的感知不同。这可能是它们在异质和物种多样性系统中共存的机制。
Variation in food resource availability can have profound effects on habitat selection and dynamics of populations. Previous studies reported higher food resource availability and fruit removal in treefall gaps than in the understorey. Therefore, gaps have been considered "keystone habitat" for Neotropical frugivore birds. Here we test if this prediction would also hold for terrestrial small mammals. In the Amazon, we quantified food resource availability in eleven treefall gaps and paired understorey habitats and used feeding experiments to test if two common terrestrial rodents (Oryzomys megacephalus and Proechimys spp.) would perceive differences between habitats. We live-trapped small mammals in eleven gaps and understorey sites for two years, and compared abundance, fitness components (survival and per capita recruitment) and dispersal of these two rodent species across gaps and understorey and seasons (rainy and dry). Our data indicated no differences in resource availability and consumption rate between habitats. Treefall gaps may represent a sink habitat for Oryzomys where individuals had lower fitness, apparently because of habitat-specific ant predation on early life stages, than in the understorey, the source habitat. Conversely, gaps may be source habitat for Proechimys where individuals had higher fitness, than in the understorey, the sink habitat. Our results suggest the presence of source-sink dynamics in a tropical gap-understorey landscape, where two rodent species perceive habitats differently. This may be a mechanism for their coexistence in a heterogeneous and species-diverse system.