Forest succession and prey availability influence the strength and scale of terrestrial-aquatic linkages in a headwater salamander system
Forest succession and prey availability influence the strength and scale of terrestrial-aquatic linkages in a headwater salamander system
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DOI：
10.1111/j.1365-2427.2008.02047.x
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发表时间：
2008-11-01
影响因子：
2.7
通讯作者：
Likens, Gene E.
中科院分区：
文献类型：
--
作者：
Greene, Brian T.;Lowe, Winsor H.;Likens, Gene E.
1.陆地和水生生态系统之间的营养联系是常见的，对干扰很敏感。然而，关于是什么导致这些联系的强度和空间尺度发生变化的信息很少。在源水火蜥蜴(Plethodontidae科)的高度水生成体中，陆地猎物的使用沿着从演替早期到晚期的河岸森林的梯度递减。为了了解这种关系的原因，我们测试了以下预测：(I)陆地猎物在演替后期森林中的丰度较低，(Ii)斑潜蝇成虫不能从溪流迁移到演替后期森林中的饲料，从而限制了获取陆地猎物的机会。我们在新罕布夏州哈伯德布鲁克实验森林的六条源头溪流上建立了100米长的研究河段。有三个地区是演替早期的森林，三个地区是演替后期的森林。我们在2005年6月和7月对无脊椎动物猎物进行了陷阱诱捕，在每个河段距离溪流0、2、5和10米处设置了三个陷阱。在2004年和2005年的6月、7月和8月，在垂直于溪流的10个长10米、宽2.5米的断面上，对每一个河段进行了夜间蜥蜴调查。在演替后期的森林中，陆地猎物丰度一直较低，这表明斑潜蝇对陆地猎物的摄取受到猎物丰度的影响。与我们的预测相反，在演替后期的森林中，斑潜蝇的成虫距离溪流更远，这表明演替后期森林的栖息地条件并不限制远离溪流的活动，这些森林中较低的陆地猎物丰度可能会导致火蜥蜴从溪流中迁移得更远。我们的研究结果为斑潜蝇利用陆地栖息地的范围提供了新的见解。更广泛地说，这些结果表明，主要的生境梯度，如森林演替，可以影响陆地-水生联系的强度和规模。将这一见解应用于沿源头溪流的植被缓冲区的设计将对淡水生态系统产生广泛的好处。
1. Trophic linkages between terrestrial and aquatic ecosystems are common and sensitive to disruption. However, there is little information on what causes variation in the strength and spatial scale of these linkages.2. In the highly aquatic adults of the headwater salamander Gyrinophilus porphyriticus (family Plethodontidae), use of terrestrial prey decreases along a gradient from early- to late-successional riparian forests. To understand the cause of this relationship, we tested the predictions that (i) terrestrial prey abundance is lower in late-successional forests, and (ii) G. porphyriticus adults cannot move as far from the stream to forage in late-successional forests, thus limiting access to terrestrial prey.3. We established 100-m long study reaches on six headwater streams in the Hubbard Brook Experimental Forest, New Hampshire. Three reaches were in early-successional forests and three were in late-successional forests. We conducted pitfall trapping for invertebrate prey in June and July of 2005, with three traps at 0, 2, 5 and 10 m from the stream at each reach. In June, July and August of 2004 and 2005, nighttime salamander surveys were conducted at each reach along ten, 10-m long by 2.5-m wide transects perpendicular to the stream.4. Abundance of terrestrial prey was consistently lower in late-successional forests, suggesting that consumption of terrestrial prey by G. porphyriticus is affected by prey abundance. Contrary to our prediction, G. porphyriticus adults moved farther from the stream in late-successional forests, suggesting that habitat conditions in late-successional forests do not limit movement away from the stream, and that lower abundances of terrestrial prey in these forests may cause salamanders to move farther from streams.5. Our results provide novel insight on the extent of terrestrial habitat use by G. porphyriticus. More broadly, these results indicate that major habitat gradients, such as forest succession, can affect the strength and scale of terrestrial-aquatic linkages. Application of this insight to the design of vegetation buffers along headwater streams would have widespread benefits to freshwater ecosystems.