Habeck Christopher W, Lindroth Richard L
Department of Zoology, University of Wisconsin, Madison, Wisconsin, United States of America.
PLoS One. 2013 Aug 19;8(8):e72717. doi: 10.1371/journal.pone.0072717. eCollection 2013.
Global atmospheric change is influencing the quality of plants as a resource for herbivores. We investigated the impacts of elevated carbon dioxide (CO2) and ozone (O3) on the phytochemistry of two forbs, Solidago canadensis and Taraxacum officinale, and the subsequent feeding behavior and growth performance of weanling prairie voles (Microtus ochrogaster) feeding on those plants. Plants for the chemical analyses and feeding trials were harvested from the understory of control (ambient air), elevated CO2 (560 µl CO2 l(-1)), and elevated O3 (ambient × 1.5) rings at the Aspen FACE (Free Air CO2 Enrichment) site near Rhinelander, Wisconsin. We assigned individual voles to receive plants from only one FACE ring and recorded plant consumption and weanling body mass for seven days. Elevated CO2 and O3 altered the foliar chemistry of both forbs, but only female weanling voles on the O3 diet showed negative responses to these changes. Elevated CO2 increased the fiber fractions of both plant species, whereas O3 fumigation elicited strong responses among many phytochemical components, most notably increasing the carbon-to-nitrogen ratio by 40% and decreasing N by 26%. Consumption did not differ between plant species or among fumigation treatments. Male voles were unaffected by the fumigation treatments, whereas female voles grew 36% less than controls when fed O3-grown plants. These results demonstrate that global atmospheric change has the potential to affect the performance of a mammalian herbivore through changes in plant chemistry.
全球大气变化正在影响植物作为食草动物资源的质量。我们研究了二氧化碳（CO₂）和臭氧（O₃）浓度升高对两种草本植物加拿大一枝黄花和蒲公英的植物化学特征的影响，以及以这些植物为食的断奶草原田鼠（Microtus ochrogaster）随后的取食行为和生长性能。用于化学分析和取食试验的植物是从威斯康星州莱茵兰德附近的阿斯彭自由空气CO₂富集（Aspen FACE）试验点的对照（环境空气）、高浓度CO₂（560 µl CO₂ l⁻¹）和高浓度O₃（环境浓度×1.5）环的林下采集的。我们将个体田鼠分配到仅接受来自一个FACE环的植物，并记录七天内的植物消耗量和断奶幼鼠体重。CO₂和O₃浓度升高改变了两种草本植物的叶片化学特征，但只有食用O₃处理植物的雌性断奶田鼠对这些变化表现出负面反应。CO₂浓度升高增加了两种植物的纤维组分，而O₃熏蒸在许多植物化学成分中引发了强烈反应，最显著的是碳氮比增加了40%，氮含量降低了26%。不同植物种类或熏蒸处理之间的消耗量没有差异。雄性田鼠不受熏蒸处理的影响，而雌性田鼠在食用O₃处理生长的植物时，生长速度比对照组慢36%。这些结果表明，全球大气变化有可能通过植物化学成分的变化影响哺乳动物食草动物的性能。
