Because ectotherm activity and metabolism are sensitive to temperature, terrestrial arthropods may be especially responsive to ongoing climatic warming. Here, we quantified responses of arthropod abundance to two years of warming in an outdoor temperature manipulation experiment at Duke Forest, North Carolina, USA. Nine open‐top chambers were individually heated year‐round from 1.5° to 5.5°C above ambient temperature. From two years of monthly pitfall trapping, we collected and identified 4,468 arthropods representing 24 orders. We initially predicted that arthropods would experience the greatest negative effects of experimental warming during the summer months, when temperatures reach their yearly maximum and arthropods may be close to their maximum thermal tolerance limits. Instead, we found that the strongest negative effects on arthropod abundance occurred during the winter and spring, when ambient temperatures are relatively cooler, whereas the effects of experimental warming on abundance were not significant during the summer or fall. During the spring of 2012, the warmest spring on record for the southeastern USA, total arthropod abundance declined 20% per °C of experimental warming. Abundance declines were driven largely by flies (Diptera), which were the most abundant insect order, representing approximately a third of all arthropods collected. The most abundant arthropod family, Mycetophilidae (fungus gnats), declined 64% per °C of warming during the spring of 2012. Although previous research on climatic warming has focused on the impact of maximum yearly temperatures on organismal performance, our results are more consistent with the cool‐season sensitivity hypothesis, which posits that arthropods adapted for cooler conditions are likely to face the strongest negative effects of warming during the cooler seasons.

中文翻译：

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春季和冬季活跃的节肢动物的数量随着变暖而下降

由于外热活动和新陈代谢对温度敏感，因此陆生节肢动物可能对持续的气候变暖特别敏感。在这里，我们在美国北卡罗来纳州的杜克森林进行的室外温度操纵实验中，定量了节肢动物的丰度对两年变暖的响应。全年将9个敞开式腔室分别从高于环境温度1.5°C加热到5.5°C。从两年的每月陷阱陷阱中，我们收集并确定了代表24个订单的4468个节肢动物。我们最初预测，在温度达到其年度最高值且节肢动物可能接近其最大热耐受极限的夏季，节肢动物将遭受实验性变暖的最大不利影响。反而，我们发现，在冬季和春季，当环境温度相对较低时，对节肢动物丰度的负面影响最大，而在夏季或秋季，实验性变暖对丰度的影响并不显着。在2012年春季，这是美国东南部有记录以来最温暖的春季，节肢动物的总丰度下降了20％（实验升温）。数量下降主要是由苍蝇（双翅目）驱动的，苍蝇是最丰富的昆虫纲，约占所收集的所有节肢动物的三分之一。在2012年春季，每升温一摄氏度，最丰富的节肢动物家族（真菌）就下降了64％。尽管先前有关气候变暖的研究都集中在年度最高温度对机体性能的影响上，