Interaction between ungulates and bruchid beetles and its effect on Acacia trees: modeling the costs and benefits of seed dispersal to plant demography
Interaction between ungulates and bruchid beetles and its effect on Acacia trees: modeling the costs and benefits of seed dispersal to plant demography
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有蹄类动物和豆象甲虫之间的相互作用及其对金合欢树的影响：模拟种子传播对植物人口学的成本和效益
作者：
Javier Rodríguez‐Pérez;K. Wiegand;D. Ward
对植物-动物相互作用的综合研究，包括相互作用的多种影响，对于辨别植物物种种群动态中每个因素的重要性是重要的。干旱稀树草原上许多相思树种的更新能力较低，这是种子传播减少和种子被高度捕食的共同结果。在这里，我们研究了有蹄类(既是种子传播者又是草食动物)和布氏甲虫(散布后的种子捕食者)是如何调节中东关键物种拉迪亚纳的种群动态的。我们开发了两个植物人口学模拟模型：第一个模型包括有蹄类动物对种子的摄取和棕榈虫对种子的捕食，而第二个模型还包括有蹄类动物的食草性。我们还包括了去除种子和体重的相互作用，因为较大的有蹄类动物破坏的种子比例较少，并提高了种子萌发。模拟表明，种子捕食对相思种群大小的负面影响被种子摄取的积极影响所补偿，在有和没有草食的情况下，种子摄取分别在50%和30%种子去除的情况下。较小的有蹄类(例如，35公斤)必须比较大的有蹄类(例如，250公斤)带走的种子多十倍，以补偿种子被捕食的负面影响。在草食模型中，苗木比例随着种子的去除而增加。管理和修复相思种子散布器是保护相思种群的关键，因为低到中等程度的种子去除可以迅速恢复它们的再生能力。
Integrative studies of plant–animal interactions that incorporate the multiple effects of interactions are important for discerning the importance of each factor within the population dynamics of a plant species. The low regeneration capacity of many Acacia species in arid savannas is a consequence of a combination of reduction in seed dispersal and high seed predation. Here we studied how ungulates (acting as both seed dispersers and herbivores) and bruchid beetles (post-dispersal seed predators) modulate the population dynamics of A. raddiana, a keystone species in the Middle East. We developed two simulation models of plant demography: the first included seed ingestion by ungulates and seed predation by bruchids, whereas the second model additionally incorporated herbivory by ungulates. We also included the interacting effects of seed removal and body mass, because larger ungulates destroy proportionally fewer seeds and enhance seed germination. Simulations showed that the negative effect of seed predation on acacia population size was compensated for by the positive effect of seed ingestion at 50 and 30% seed removal under scenarios with and without herbivory, respectively. Smaller ungulates (e.g., <35 kg) must necessarily remove tenfold more seeds than larger ungulates (e.g., >250 kg) to compensate for the negative effect of seed predation. Seedling proportion increased with seed removal in the model with herbivory. Managing and restoring acacia seed dispersers is key to conserving acacia populations, because low-to-medium seed removal could quickly restore their regeneration capacity.