Aboveground plant-insect interaction webs and associated processes along a plant diversity gradient

传粉是植物繁殖的关键，植物多样性是吸引传粉者多样性和传粉频率的重要因素。然而，很少有人研究花性状，授粉，以及其他生物相互作用如何影响植物繁殖的植物生物多样性下降的情况下。本子项目的主要目标是：（1）测定花的化学性状，并与花的形态性状一起解释植物多样性梯度沿着的访花多样性和频率：（2）通过比较传粉昆虫的C：N：P比值和传粉昆虫的繁殖成功率，研究传粉昆虫与花的互利相互作用的化学计量学;（3）在主要和（新）基于性状的实验中分析访花和植物-传粉者相互作用网络，包括入侵者在植物-传粉者相互作用网络中的整合：（4）在（新）基于性状的实验中研究植物种特异性对授粉和植物繁殖的反应;（5）在温室实验中应用的手授粉与袋授粉处理将鉴定耶拿实验的主要开花植物物种的育种系统（自主自花授粉与异花授粉）。该子项目将收集植物特有的性状（i）解释访花，授粉和植物繁殖，以及（ii）将花的性状添加到基于性状的整体建模中。因此，该子项目是至关重要的，以了解植物繁殖依赖于植物多样性，从而了解植物种群动态在草原上，不同的植物物种丰富度。

Pollination is most critical to plant reproduction and plant diversity is important to attract high pollinator diversity and pollination frequency. However, it has rarely been studied how flower traits, pollination, and other biotic interactions affect plant reproduction under a scenario of plant biodiversity decline. In this subproject, the following main objectives will be addressed: (1) Chemical flower traits will be measured and used together with morphological flower traits to explain the diversity and frequency of flower visits along the long-term plant diversity gradient; (2) The stoichiometry of mutualistic pollinator-flower interactions will be addressed by comparing C:N:P ratios of pollinators with the reproduction success of pollinators in the main experiment; (3) Flower visitation and plant-pollinator interaction webs will be analysed in the main and the (new) trait-based experiment including the integration of invaders in plant-pollinator interaction webs; (4) Plant species-specific responses to pollination and plant reproduction will be studied in the (new), trait-based experiment; (5) Hand- versus bagged pollination treatments applied in a greenhouse experiment will identify the breeding systems (autonomous self- versus cross-pollination) of major flowering plant species of the Jena experiment. The subproject will collect plant-specific traits (i) to explain flower visitation, pollination, and plant reproduction, and (ii) to add flower traits to the overall trait-based modelling. The subproject is therefore critical to understand plant reproduction dependent on plant diversity, and hence to understand plant population dynamics in grasslands that differ in plant species richness.