Department of Botany, Stockholm University, S-10691 Stockholm, Sweden;
Am J Bot. 2002 Aug;89(8):1295-302. doi: 10.3732/ajb.89.8.1295.
We experimentally investigated how pollinator- and herbivore-induced changes influence the performance of the long-lived herb Primula veris. Eight treatments that corresponded to natural factors normally affecting this species were designed to enhance or reduce reproductive success and resource availability (flower removal, supplementary pollination, defoliation). During the experimental season and in the following year we quantified responses in terms of survival, growth, and seed production of reproductive plants. Matrix population models were used to calculate population growth rate using the demographic parameters recorded in permanent plots and respective treatment groups. Seed production was not limited by pollen availability, and we found no evidence of a cost of reproduction. Leaf removal had either no effect or a negative effect on future performance, depending on the timing of removal. Defoliation early in the season reduced current seed production and future growth, whereas removal during fruit development affected performance in the following year. Demographic models suggest that leaf damage has a smaller negative impact than flower removal on overall performance in this population. Our results suggest that the source-sink paths vary over the season and that the timing of herbivory may influence the extent to which effects are carried over to subsequent reproductive seasons.
我们通过实验研究了传粉者和食草动物诱导的变化如何影响长寿草本报春花的表现。设计了八个处理方法来增强或减少生殖成功和资源可用性，这些处理方法对应于通常影响该物种的自然因素（花去除、补充授粉、除叶）。在实验季节和下一年，我们根据生殖植物的存活、生长和种子产量来量化响应。使用矩阵种群模型，根据永久样地和各自处理组记录的人口统计参数来计算种群增长率。种子产量不受花粉可用性的限制，并且我们没有发现繁殖成本的证据。叶片去除对未来的表现要么没有影响，要么产生负面影响，这取决于去除的时间。在季节早期除叶会减少当前的种子产量和未来的生长，而在果实发育期间除叶会影响下一年的表现。人口统计模型表明，叶片损伤对该种群整体表现的负面影响小于花去除。我们的结果表明，源-汇途径在整个季节中会发生变化，并且食草动物的时间可能会影响影响延续到下一个生殖季节的程度。
