Spatiotemporal variation in predispersal seed predation intensity
Spatiotemporal variation in predispersal seed predation intensity
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DOI：
10.1007/bf00329046
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发表时间：
1996-12-01
期刊：
影响因子：
2.7
通讯作者：
Ehrlen, J
中科院分区：
文献类型：
--
作者：
Ehrlen, J
在11个固定样地中，研究了扩散前种子被豆象（Bruchus atomarius，鞘翅目，豆象科）捕食对多年生森林草本植物-种子捕食和参数描述种内邻居距离，植物大小，花序大小，开花物候和当前和以前的草食动物的损害进行了测量。此外，从所有地块的人口统计信息进行了分析，使用过渡矩阵人口模型，以估计种子捕食对人口增长率的影响。扩散前种子捕食率年间差异显着。图平均值范围为0至83.7%。然而，大部分的变异发生在个体之间。在个体内，各年的捕食率没有一致性。暴露于食草动物，植物的大小和开花物候没有影响捕食率，但个体具有较大的花序遭受显着较高的捕食。种子捕食作用在L. Vernus不受个体相邻距离的影响，但与样地内种子的平均密度呈正相关，表明种子捕食在斑块水平上具有密度依赖性。由于种子捕食的人口增长率的减少范围从0到7.6%。种群增长率对种子产量减少的敏感性在不同年份和地块之间有很大差异。这种变异主要是由于种子和幼苗的繁殖价值不同。种子捕食的强度与种群增长率的变化无关。研究结果表明，外部因素（如种子捕食）对种群增长率的影响在很大程度上取决于所调查种群的人口转变率。
The effect of predispersal seed predation by Bruchus atomarius (Bruchidae, Coleoptera) on individual performance and population dynamics of the perennial forest herb, Lathyrus vernus (Leguminosae), was investigated in 11 permanent plots over 4 years. Seed predation and parameters describing intra-specific neighbour distance, plant size, inflorescence size, flowering phenology and current and previous herbivore damage were measured on all plants. Tn addition, demographic information from all plots was analysed using transition matrix population models in order to estimate the influence of seed predation on population growth rates. Predispersal seed predation rates differed significantly among years. Plot averages ranged from 0 to 83.7%. However, most of the variation occurred among individuals. Within individuals there was no consistency in pre dation rates among years. Exposure to herbivory, plant size and flowering phenology did not affect predation rates but individuals with larger inflorescences suffered from significantly higher predation. Seed predation in L. vernus was not influenced by neighbour distances of individual plants but it was positively correlated with the average density of seeds within plots, suggesting that seed predation is density dependent at the patch level. The reduction in population growth rate due to seed predation ranged from 0 to 7.6%. The sensitivity of population growth rate to reductions in seed production varied considerably among years and plots. This variation was mainly due to differences in the reproductive value of seeds and seedlings. The intensity of seed predation over the range found was not correlated with changes in population growth rate. The results of this study suggest that the influence of external factors, like seed predation, on population growth rate largely depends on the demographic transition rates in the investigated population.