Avian species richness and abundance shows stronger response to bison grazing intensity than to ecosystem productivity

Temperate grassland ecosystems are one of the most threatened ecosystems worldwide, and their loss endangers the grassland songbirds that rely upon them. This guild of birds has shown long-term declines in North America. At the same time, American bison (Bison bison) are becoming more common through reintroductions, and they may make significant modifications to grassland songbird habitat. To support conservation for this guild, we sought to understand the importance of bison grazing and ecosystem productivity to the species richness, occupancy, and abundance of this avian community. We conducted dependent double-observer bird counts, measured bison grazing intensity with patty counts, and used remote-sensed Normalized Difference Vegetation Index (NDVI) data to measure ecosystem productivity. Our work took place in the National Bison Range near Moiese, Montana and in Yellowstone National Park in Wyoming. We found that species richness was positively correlated with patty counts, and had...

温带草原生态系统是全球受威胁最为严重的生态系统之一，其退化与消失会直接威胁依赖其生存的草原鸣禽种群。该鸟类生态类群在北美地区已呈现长期种群衰退趋势。与此同时，通过野化放归，美洲野牛（Bison bison）的种群数量正逐步回升，而它们可能会对草原鸣禽的栖息环境造成显著改变。为助力该类鸣禽的保护工作，本研究旨在明确美洲野牛的放牧行为与生态系统生产力对该鸟类群落的物种丰富度、占据率以及种群丰度的影响机制。本研究采用依赖型双观察者鸟类计数法开展野外调查，通过粪团计数法量化美洲野牛的放牧强度，并借助遥感归一化差值植被指数（Normalized Difference Vegetation Index, NDVI）数据评估生态系统生产力。本研究的调查区域位于美国蒙大拿州莫伊塞附近的国家野牛保护区，以及怀俄明州的黄石国家公园。研究结果显示，物种丰富度与粪团计数结果呈显著正相关，且……