Nelson Rebecca A, Borer Elizabeth T, Seabloom Eric W
Department of Wildland Resources and the Ecology Center Utah State University Logan Utah USA.
Department of Environmental Science & Policy University of California, Davis Davis California USA.
Ecol Evol. 2025 Sep 13;15(9):e72153. doi: 10.1002/ece3.72153. eCollection 2025 Sep.
Nutrient enrichment has decreased the diversity and abundance of wildflower species, raising questions about whether nutrient enrichment can further decrease the diversity and abundance of pollinators that rely on wildflowers. Whether the effects of nutrient enrichment on plant-pollinator interactions differ by nutrient type remains an open question. Moreover, plant family and flower color, two core axes of pollination niches, may further mediate how wildflowers and their pollinators respond to nutrient enrichment. We tested these questions using a nutrient addition experiment replicated at three grasslands in California, a global plant diversity hotspot. We found that adding nitrogen increased the floral abundance of Asteraceae, while decreasing that of Fabaceae, Geraniaceae, Iridaceae, and Euphorbiaceae. Adding phosphorus and potassium in the absence of nitrogen produced the opposite effects. Pollinator abundance and composition varied strongly by floral family, suggesting that these differing responses to nutrient addition by floral family may alter pollinator community composition. Nitrogen addition decreased the abundance of native blue, native green, and exotic pink flowers, while increasing the abundance of native and exotic yellow and exotic purple flowers. Consequently, nitrogen addition increased pollinator abundance on purple flowers, while decreasing pollinator abundance on pink flowers. Purple and yellow Asteraceae species, which increased under nitrogen enrichment, acted as core hubs in structuring the plant-pollinator network. Our findings suggest that the type of nutrient, plant family, and flower color modulate how plant-pollinator interactions respond to eutrophication.
养分富集降低了野花物种的多样性和丰度，这引发了关于养分富集是否会进一步降低依赖野花的传粉者的多样性和丰度的问题。养分富集对植物-传粉者相互作用的影响是否因养分类型而异仍是一个悬而未决的问题。此外，植物科属和花色作为传粉生态位的两个核心轴，可能会进一步调节野花及其传粉者对养分富集的反应。我们在加利福尼亚州的三个草原（一个全球植物多样性热点地区）进行了一项重复的养分添加实验，以检验这些问题。我们发现，添加氮会增加菊科的花量，同时减少豆科、牻牛儿苗科、鸢尾科和大戟科的花量。在不添加氮的情况下添加磷和钾则产生相反的效果。传粉者的丰度和组成因花的科属而有很大差异，这表明这些花的科属对养分添加的不同反应可能会改变传粉者群落的组成。添加氮会减少本地蓝色、本地绿色和外来粉色花朵的丰度，同时增加本地和外来黄色以及外来紫色花朵的丰度。因此，添加氮会增加紫色花朵上传粉者的丰度，同时减少粉色花朵上传粉者的丰度。在氮富集条件下增加的紫色和黄色菊科物种，在构建植物-传粉者网络中起到了核心枢纽的作用。我们的研究结果表明，养分类型、植物科属和花色会调节植物-传粉者相互作用对富营养化的反应。
