松嫩草地蝗虫种群动态对降水格局变化与放牧干扰的响应及其机制

Grasshoppers are important components in grasslands, and their population dynamics play critical role for the functioning and stability of ecosystem. Currently, grasslands are susceptible to climate change and human disturbance. In this study, a field experiment with manipulated grazing intensity by large herbivores and simulated precipitation patterns in a meadow steppe will be conducted to examine the responses of the density and spatial patterns of grasshopper population to different grazing intensity (no grazing, moderate grazing, and heavy grazing) and changed precipitation patterns (natural precipitation, and increased precipitation) — the two important drivers in grassland ecosystems. The changes in grasshopper population dynamics and regulating effects of grazing and altered precipitation will be understood and recognized profoundly by studying the responses of the dynamics of density and spatial distribution of grasshoppers under different grazing intensity, increased precipitation, and their interactions in grasslands. The mechanisms of changed grasshopper population dynamics will be interpreted by analyzing the effects of grazing, altered precipitation, and their interactions on plant community diversity and composition, habitat microclimate, and the relationships between grasshopper dynamics and environmental factors in natural complex grasslands. This work will improve the understanding of the predictions on grasshopper outbreak under climate change and human disturbance, of the maintenances of ecosystem functioning, and of the sustainability of health in grasslands. Likewise, the research will provide the guide of drawing up scientific and reasonable grassland management strategies for controlling grasshopper outbreak.

蝗虫是草地生态系统的重要组成部分，其种群动态变化对草地生产与生态功能及稳定性维持有至关重要的作用。当前，草地面临气候变化与人类活动的协同作用影响，本研究通过松嫩草地上的受控放牧实验和人工模拟降水格局变化实验平台，开展蝗虫种群数量变化与空间分布模式对不同放牧强度（无牧、中度放牧和重度放牧）与降水量变化（自然降水和增加降水）的互作的响应及其机制研究。通过对放牧与降水变化的互作影响下的蝗虫种群数量与空间格局变化的响应分析，深入理解蝗虫种群的发生规律以及人为干扰和气候变化的协同作用效应；通过对蝗虫种群数量与空间格局与植物群落和生境微气候等环境因子之间的相互关系分析，探讨放牧干扰与降水变化对蝗虫种群动态变化影响的作用机制。本研究对预测气候变化与人类活动影响下的蝗虫种群爆发动态、维持草地生态系统功能与可持续健康发展有重要的科学价值，同时为制定科学合理的草地管理措施以实现蝗灾可持续控制提供理论依据。

本项目基于人类活动和气候变化条件下草地蝗虫的响应入手进行研究，通过天然草地的放牧与降水格局变化的控制实验，研究蝗虫多样性和数量以及蝗虫的空间格局响应，同时进一步研究了植食性昆虫与捕食性昆虫多样性。通过本研究发现，在降水量增加条件下，进行适度放牧能够维持蝗虫物种丰富度和增加数量，重度放牧强度不同程度影响蝗虫数量，并且这种效应是蝗虫种类依赖的；同时，还发现适度放牧强度使蝗虫趋向均匀分布，而重度放牧使蝗虫利于聚集。蝗虫多样性的变化主要受到植物多样性的影响，而蝗虫数量变化则是植被结构影响较为重要；蝗虫种群的空间分布格局同时受到生境和食物的共同作用。此外，通过本研究检验了营养级效应的重要假说，本研究结论得出，放牧和降水量变化可以通过植物多样性调节植食性昆虫多样性（支持Resource Diversity 假说），通过调节植食性昆虫个体数量影响捕食性昆虫多样性（支持More Individual 假说）。因此，在降水量增加条件下，进行适度放牧管理草地有利于减少蝗灾的发生，使草地能够可持续利用，同时该研究对于深入理解环境变化下的营养级效应以及草地生态系统的昆虫食物网络有重要意义。