Data_Sheet_1_Experimental Climate Warming Reduces Floral Resources and Alters Insect Visitation and Wildflower Seed Set in a Cereal Agro-Ecosystem.pdf

Declines in pollinating insects and wildflowers have been well documented in recent years. Climate change is an emerging threat to insect pollinators and their food plants, but little is known about how whole communities of interacting species will be affected or what impacts there may be on ecosystem services such as pollination. Using a novel open-air field experiment, we simulated an increase in temperature of 1.5°C and rainwater of 40% for two growing seasons to investigate how climate change may impact several within-field features of temperate arable agro-ecosystems: (1) wildflower floral resources; (2) insect visitation; (3) flower-visitor network structure; and (4) wildflower seed set. Experimental warming reduced total floral abundance by nearly 40%, and nectar volumes by over 60% for two species. The species richness of the visiting insects and flowering plants (dominated by annuals) were unaffected by warming, and while a negative impact on visitor abundance was observed, this effect appears to have been mediated by different community compositions between years. Warming increased the frequency of visits to flowers and the complexity of the flower-visitor interaction networks. Wildflower seed set was reduced in terms of seed number and/or weight in four of the five species examined. Increased rainwater did not ameliorate any of these effects. These findings demonstrate the adverse impacts that climate warming might have on annual wildflowers in arable systems and the pollinating insects that feed on them, highlighting several mechanisms that could drive changes in community composition over time. The results also reveal how cascading impacts within communities can accumulate to affect ecosystem functioning.

近年来，关于授粉昆虫和野生花卉数量减少的现象已得到充分记录。气候变化正逐渐成为威胁昆虫授粉者和其食物植物的新兴威胁，然而，关于整个相互作用物种群落将如何受到影响，以及对生态系统服务如授粉可能产生的影响知之甚少。通过一项新颖的露天田间实验，我们对两个生长季节内的温度上升1.5°C和降雨量增加40%进行了模拟，以探究气候变化可能对温带耕作农业生态系统中若干田间特征的影响：包括（1）野生花卉花资源；（2）昆虫访问；（3）花-访客网络结构；（4）野生花卉种子结成。实验性升温导致总花卉数量减少了近40%，两种物种的花蜜量超过60%。访问昆虫和开花植物的物种丰富度（由一年生植物主导）未受升温影响，尽管观察到访客数量的负面影响，但这种影响似乎由不同年份的群落组成差异所调节。升温增加了对花卉的访问频率和花-访客互动网络的复杂性。在考察的五种物种中，有四种的野生花卉种子结成在种子数量和/或重量方面有所减少。增加的降雨量并未改善这些影响。这些发现展示了气候变暖可能对耕作系统中的一年生野生花卉及其食用的授粉昆虫产生的不利影响，并突出了可能导致群落组成随时间变化的若干机制。结果还揭示了群落内部级联影响如何累积，进而影响生态系统功能。