Feener Donald H, Schupp Eugene W
Department of Biology, University of Utah, Salt Lake City, UT 84112, USA e-mail:
Department of Rangeland Resources and the Ecology Center, Utah State University, Logan, UT 84322, USA, , , , , , US.
Oecologia. 1998 Aug;116(1-2):191-201. doi: 10.1007/s004420050579.
Natural formation of treefall gaps plays an integral role in the ecological and evolutionary dynamics of many tropical forests, affecting the spatiotemporal distribution of plants and the animals that interact with them. This study examines the impact of treefall gaps on the spatial and temporal patchiness of ant assemblages in a moist lowland forest in Panama. Using pitfall traps and honey baits, we compared ant assemblages in five 1 to 2-year-old treefall gaps (ca 100 m) and five adjacent plots (ca 100 m) in undisturbed forest understory at three different times of year (late wet season, late dry season, and early wet season). We found little evidence that ant assemblages respond dramatically to the formation of treefall gaps and the differences in habitat qualities they produce. Ant abundance, species richness, species composition, and rates of resource discovery did not differ between gaps and forest understory. However, we did find significant differences in numerical abundance related to forest stratum (ground vs vegetation) and resource type in pitfall traps (oil-cockroach vs honey), and significant differences in ant species richness and rates of resource discovery across seasons. While habitat effects by themselves were never statistically significant, habitat and seasonal differences in species richness interacted significantly to produce complex, season-dependent differences among gap and forest habitats. These results suggest that the formation of natural treefall gaps has less of an effect on Neotropical ant assemblages compared to other groups of organisms (e.g., plants, birds) or other causes of patchiness (e.g., ant mosaics, moisture availability, army ant predation). The results of our study also have important implications for the underlying causes of habitat differences in the distribution of ant-defended plants.
树木倾倒形成的林窗在许多热带森林的生态和进化动态中起着不可或缺的作用，影响着植物以及与植物相互作用的动物的时空分布。本研究考察了树木倾倒形成的林窗对巴拿马湿润低地森林中蚂蚁群落时空斑块性的影响。我们使用陷阱诱捕器和蜂蜜诱饵，在一年中的三个不同时间（雨季末期、旱季末期和雨季初期），比较了五个1至2年树龄的树木倾倒林窗（约100米）和未受干扰森林林下的五个相邻样地（约100米）中的蚂蚁群落。我们几乎没有发现证据表明蚂蚁群落对树木倾倒形成的林窗及其所产生的栖息地质量差异有显著反应。林窗和森林林下的蚂蚁丰度、物种丰富度、物种组成以及资源发现率并无差异。然而，我们确实发现陷阱诱捕器中与森林层次（地面与植被）和资源类型（油蟑螂与蜂蜜）相关的数量丰度存在显著差异，并且不同季节间蚂蚁物种丰富度和资源发现率也存在显著差异。虽然栖息地本身的影响在统计学上并不显著，但物种丰富度的栖息地和季节差异之间存在显著相互作用，从而在林窗和森林栖息地之间产生复杂的、依赖季节的差异。这些结果表明，与其他生物群体（如植物、鸟类）或其他斑块性成因（如蚂蚁镶嵌、水分可利用性、行军蚁捕食）相比，天然树木倾倒林窗的形成对新热带地区蚂蚁群落的影响较小。我们的研究结果对于以蚂蚁为防御机制的植物分布中栖息地差异的潜在成因也具有重要意义。
