退化高寒草地恢复中植物-传粉者互作网络构建模式与机理

Intensive effect of anthropogenic perturbations on habitats has affected plant community, insect community and pollination process, and further changed plant-pollinator interaction networks and pollination service. As interaction networks between organisms underpin the whole ecosystem, recently people have focused on restoring ecosystem functioning, especially the structure of interaction networks rather than species diversity. In the process of ecological restoration, reconstruction of solid interaction networks between species can restore lost interactions and diversity, which is the core for repairing and protecting ecological functions. Due to the effects of overgrazing and climate changes, the alpine meadow of Qinghai-Tibet Plateau experienced the decline of biodiversity and production, severe degradation of grassland and damage of ecosystem functions of water resource conservation and diversity protection. This project aims to the restoring mechanism of degraded alpine meadow, to study the dynamic of plant-pollinator interaction networks and change of diversity by the regularly restoring measure of fencing and modifying timing of grazing during the growth season of community. This will determine the key species including plants and insects and their roles in the process of community restoration, and reveal the construction mechanism of interaction networks and critical parameters involved in stability of community, and establish ecological theory for restoring degraded alpine meadow.

人为活动对生境改造和扰动强度的加大不但影响植物群落、传粉者群落和传粉过程，还能改变传粉互作网络及传粉服务。因为生物之间的互作关系网络维持着整个生态系统，近年来人们开始注意恢复生态系统的功能，尤其是物种间的互作网络结构而不仅仅物种多样性。生态恢复过程中通过重建坚固的物种间作用网络可以恢复丧失的交互作用和生物多样性，这是恢复和保护生态功能的关键。青藏高原地区近年来在过度放牧和全球气候变化影响下，生物多样性下降，生产力降低，草地严重退化，水源涵养的生态功能及生物多样性保护功能也已严重受损。本项目将针对青藏高原东部退化高寒草地的恢复机理，在普遍采用的设置围栏、调整放牧时间的恢复措施中探讨植物与传粉者互作网络结构动态与多样性变化，揭示群落恢复中的关键物种及其作用，阐明植物-传粉者网络构建机理和影响群落稳定性的重要参数，完善退化高寒草地恢复的相关理论。

在青藏高原，放牧制度的调整（如生长季禁牧）是一项广泛采用的草地恢复措施。本研究首次评估了生长季禁牧措施对于青藏高原高寒草甸中植物-传粉者互作网络的影响和维持物种多样性的机制。研究表明生长季禁牧措施能够增加草地的花资源和传粉者多样性，以及传粉网络的稳定性。在恢复后的样地中，植物繁殖的花粉限制程度降低，结子率增加。同时，研究区高寒草甸中植物-植物的相互作用主要是促进或中性，在禁牧群落中竞争作用减少，物种之间的促进作用占主导地位。传粉者介导的植物间相互作用带来的好处超过了与传粉者共享带来的同种花粉的损失（成本），花性状相似性是影响这些相互作用的驱动因素，花性状与中心物种相似的植物可以从传粉者介导的种间花粉转移中受益，最终保障植物的繁殖适合度。因此，本项目揭示了植物生长季节采用禁牧制度有利于植物繁殖和物种多样性维持机制，生长季禁牧是一项有效的并且可推广的草地恢复措施。