Masting and trophic cascades: interplay between rowan trees, apple fruit moth, and their parasitoid in southern Norway
Masting and trophic cascades: interplay between rowan trees, apple fruit moth, and their parasitoid in southern Norway
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桅杆和营养级联：挪威南部罗文树、苹果果蛾及其寄生蜂之间的相互作用
DOI：
10.1111/j.0030-1299.2004.12694.x
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发表时间：
2004
期刊：
影响因子：
3.4
通讯作者：
S. Kobro
中科院分区：
文献类型：
--
作者：
A. Satake;O. Bjørnstad;S. Kobro
我们分析了挪威南部罗文的浆果产量，并考察了罗文桅杆对优势种捕食性天敌及其寄生蜂动态的影响。苹果小食心蛾Argyresthia congigella Zeller是苹果小食心虫Rowan的一种预扩散种子捕食性天敌。苹果蛾的幼虫以罗文浆果为食，而罗文浆果又会受到寄生黄蜂Microgaster Poltes Marsh的攻击。我们在罗文发现了典型的主干：浆果产量在不同年份之间存在差异(平均变异系数为1.02)，并且在大范围内具有空间同步性(平均相关系数为0.67)。在西方，浆果的生产代表着两年的周期，而在挪威东部，则代表着三年的周期。飞蛾和寄生蜂的丰度也随着年份的变化而变化，并且在空间上是同步的。随着营养水平的增加，空间同步性降低，周期性变得不明显。基于一个简单的种群动力学模型，我们试图评估捕食者饱和的两个不同组成部分：功能饱和和数量饱和。观察到的种子捕食模式证明，在这个系统中，功能性饱和和数量饱和都在起作用。在不同地点的比较中，具有更多可变浆果产量的Rowan树在减少对种子捕食者的损失方面更有效。通过寄主丰度的波动，寄生蜂似乎也经历了饱和。这些结果表明，罗文桅杆具有适应的基础，这影响了较高营养级的动态。
We analyzed berry production in rowan, Sorbus aucuparia L., in southern Norway and examined the ramifying effects of rowan masting on the dynamics of the dominant seed predator and its parasitoid. The apple fruit moth, Argyresthia conjugella Zeller, is a pre-dispersal seed predator of rowan. The larva of the apple fruit moth rely on rowan berries, which in turn is attacked by the parasitoid wasp, Microgaster politus Marsh. We found classic masting in rowan: berry production varied across years (the mean coefficient of variation=1.02) and was spatially synchronized at large scale (the averaged correlation coefficient = 0.67). Berry production represented a two-year cycle in western but a three-year cycle in eastern Norway. The abundance of the moth and the parasitoid also varied across years and were spatially synchronized. The degree of spatial synchrony decreased and cyclicity became obscure with increasing trophic level. We attempted to assess two different components to the predator satiation, functional and numerical satiations, based on a simple population dynamics model. The observed pattern of seed predation testified that both of functional and numerical satiations were at work in this system. In a comparison at different locations, rowan trees with more variable berry production were more effective in reducing losses to the seed predator. The parasitoids also seemed to experience satiation through the fluctuation in their host abundance. These results show that rowan masting has an adaptive foundation, which impacts the dynamics of higher trophic levels.