Edge effects decrease ant-derived benefits to seedlings in a neotropical savanna
Edge effects decrease ant-derived benefits to seedlings in a neotropical savanna
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DOI：
10.1007/s11829-012-9229-9
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发表时间：
2013-04-01
影响因子：
1.6
通讯作者：
Oliveira, Paulo S.
中科院分区：
文献类型：
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作者：
Christianini, Alexander V.;Oliveira, Paulo S.
边缘效应可能导致植物-动物相互作用的变化，如种子传播，这对植物再生至关重要。然而，对边缘效应的研究在巴西塞拉多被忽视，这是新热带最大的稀树草原。我们评估了Cerrado的边缘效应对红杉(红木科)再生的影响，这是一种得益于蚂蚁传播种子的灌木。我们比较了空气温度、相对湿度和水汽压差，以及鹿角边缘和内部之间一水硬铝石相互作用的频率和结果。塞拉多的内部可能比其边界潮湿，但种子的生产和萌发在塞拉多的边缘和内部没有区别。蚂蚁在碎片边缘附近移走的种子比碎片内部的种子多。然而，桃金娘亚科蚂蚁在边缘处主导蚂蚁与果实的相互作用。这些蚂蚁很可能不会给种子带来什么好处。靠近蚂蚁巢穴生长的白背飞虱幼苗的成活率高于远离巢穴生长在塞拉多内部的幼苗，但这种影响在边缘附近消失。由于边缘较高的蒸发需求造成的广泛的幼苗死亡可能是这种影响的部分原因。此外，Ponerinae的巢穴在边缘附近的停留时间也较短，减少了蚂蚁群体活动可能带来的好处，如营养丰富和对昆虫草食动物的保护。边缘效应可能会改变塞拉多碎片中植被的结构和动态，部分原因是这里展示的互惠作用的崩溃。
Edge effects may lead to changes in mutualistic plant-animal interactions, such as seed dispersal, that are critical to plant regeneration. However, research into edge effects is neglected in the Brazilian cerrado, the largest neotropical savanna. We evaluated the consequences of edge effects in the cerrado for the regeneration of Erythroxylum pelleterianum (Erythroxylaceae), a shrub that benefits from seed dispersal by ants. We compared air temperature, relative humidity, and vapor pressure deficit, as well as the frequency and outcome of ant-diaspore interactions between cerrado edges and interiors. The inner portion of cerrado was likely to be moister than its borders, but seed production and germination did not differ between edge and interior of cerrado. Ants removed more seeds near fragment edges than at the interior. However, Myrmicinae ants dominated ant-fruit interactions at edges. These ants are likely to provide few benefits to the seeds. Seedlings of E. pelleterianum growing close to Ponerinae ant nests showed higher survival than seedlings growing away from nests in the interior of cerrado, but such effect disappeared near edges. Widespread seedling mortality due to a higher evaporative demand at edges may partially account for this effect. Furthermore, Ponerinae's nests also showed a lower residence time near edges, decreasing possible benefits derived from ant colony activity such as nutrient enrichment and protection against insect herbivores. Edge effects could change the structure and dynamics of vegetation in cerrado fragments, due in part to the collapse of the mutualistic interactions demonstrated here.