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The structure of plant-pollinator mutualistic interactions is important for pollination network stability and robustness in the face of environmental change. Even slight changes in seasonal or annual precipitation patterns can disrupt the critical plant-pollinator mutualisms that comprise healthy pollination systems, primarily through changes in the availability of floral resources. Increased instances of drought across regions, especially in the southwestern United States, is a likely threat to plant and pollinator species richness, phenology, and mutualistic associations. In this paper, we evaluate temporal changes in plant-pollinator communities of the San Francisco Peaks in northern Arizona between two years with substantially different cumulative precipitation totals. Specifically, we evaluate how plant and pollinator species abundance, richness, mutualistic interactions, and degree of pollinator generalization differed between two years, which we refer to as the “wet year” (2017) and “dry year” (2018), and how these shifts may be further impacted at three different life zones (elevation zones). We determine that plant richness and abundance decreased in the dry year, and overall pollinator species generalization increased in the dry year, with a larger number of species considered to be “core generalists”. Additionally, the timing of plant and pollinator activity periods were less consistent in the dry year; there was delayed blooming for many floral resources until after monsoon rains began, and insect activity tended to start and continue later in the season for all life zones. A greater number of pollinator species considered to be core generalists in the dry year, despite fewer floral resources until later in the season, may suggest some degree of plasticity when it comes to partner choice, which may be buffering this pollination system from community collapse when resources are scarce. With changing climate, including unpredictable precipitation worldwide, studies to uncover which pollinator species and plant-pollinator associations are most critical for community stability in drier conditions is important for informing conservation decisions on local scales.

植物-传粉者互利互作（plant-pollinator mutualistic interactions）的结构，对于环境变化下传粉网络（pollination network）的稳定性与抗干扰能力至关重要。即便季节或年际降水格局的微小变化，也可能通过改变花卉资源可获得性，破坏构成健康传粉系统的关键植物-传粉者互利关系。全球多地干旱事件愈发频发，尤以美国西南部为甚，这或对植物与传粉者的物种丰富度、物候（phenology）及互利关联构成威胁。本研究针对亚利桑那州北部旧金山峰（San Francisco Peaks）区域的植物-传粉者群落，对比了累积降水量差异显著的两个年份间的时间动态变化。具体而言，本研究对比了被分别称为"湿年（2017年）"与"干年（2018年）"的两个年份中，植物与传粉者的物种多度、丰富度、互利互作关系以及传粉者泛化度（pollinator generalization）的差异，并探究了这一变化在三个不同的生活型带（life zones，即海拔带elevation zones）中可能受到的进一步影响。研究结果显示，干年中植物的物种丰富度与多度均有所下降，而整体传粉者的物种泛化度有所提升，被归为"核心泛化种（core generalists）"的物种数量更多。此外，干年中植物与传粉者的活动周期一致性更差：多数花卉资源的开花时间推迟至季风雨降临之后，且所有生活型带的昆虫活动均倾向于在季候更晚时段启动并持续。尽管干年中季候后期之前的花卉资源更为匮乏，但此时被归为核心泛化种的传粉者数量更多，这或表明传粉者在伴侣选择方面存在一定程度的可塑性，这种可塑性或能在资源匮乏时避免该传粉系统发生群落崩溃。在全球气候变迁、降水模式愈发不可预测的背景下，探究在干旱条件下哪些传粉者物种与植物-传粉者关联对群落稳定性最为关键，可为局地尺度的保护决策提供科学依据。