Asshoff Roman, Hättenschwiler Stephan
Institute of Botany, University of Basel, Schönbeinstrasse 6, 4056 Basel, Switzerland.
Oecologia. 2005 Jan;142(2):191-201. doi: 10.1007/s00442-004-1714-0. Epub 2004 Oct 5.
The consequences for plant-insect interactions of atmospheric changes in alpine ecosystems are not well understood. Here, we tested the effects of elevated CO(2) on leaf quality in two dwarf shrub species (Vaccinium myrtillus and V. uliginosum) and the response of the alpine grasshopper (Miramella alpina) feeding on these plants in a field experiment at the alpine treeline (2,180 m a.s.l.) in Davos, Switzerland. Relative growth rates (RGR) of M. alpina nymphs were lower when they were feeding on V. myrtillus compared to V. uliginosum, and were affected by elevated CO(2) depending on plant species and nymph developmental stage. Changes in RGR correlated with CO(2)-induced changes in leaf water, nitrogen, and starch concentrations. Elevated CO(2) resulted in reduced female adult weight irrespective of plant species, and prolonged development time on V. uliginosum only, but there were no significant differences in nymphal mortality. Newly molted adults of M. alpina produced lighter eggs and less secretion (serving as egg protection) under elevated CO(2). When grasshoppers had a choice among four different plant species grown either under ambient or elevated CO(2), V. myrtillus and V. uliginosum consumption increased under elevated CO(2) in females while it decreased in males compared to ambient CO(2)-grown leaves. Our findings suggest that rising atmospheric CO(2) distinctly affects leaf chemistry in two important dwarf shrub species at the alpine treeline, leading to changes in feeding behavior, growth, and reproduction of the most important insect herbivore in this system. Changes in plant-grasshopper interactions might have significant long-term impacts on herbivore pressure, community dynamics and ecosystem stability in the alpine treeline ecotone.
高山生态系统中大气变化对植物与昆虫相互作用的影响尚未得到充分了解。在此，我们在瑞士达沃斯高山林线（海拔2180米）的田间试验中，测试了高浓度二氧化碳对两种矮灌木（欧洲越桔和湿地越桔）叶片质量的影响，以及以这些植物为食的高山蚱蜢（高山米拉蚱蜢）的反应。与以湿地越桔为食相比，高山米拉蚱蜢若虫取食欧洲越桔时的相对生长率较低，且相对生长率受高浓度二氧化碳的影响，具体取决于植物种类和若虫发育阶段。相对生长率的变化与二氧化碳诱导的叶片水分、氮和淀粉浓度变化相关。高浓度二氧化碳导致雌性成虫体重减轻，与植物种类无关，且仅使取食湿地越桔的发育时间延长，但若虫死亡率无显著差异。在高浓度二氧化碳环境下，新羽化的高山米拉蚱蜢成虫产出的卵更轻，分泌的用于保护卵的物质更少。当蚱蜢在四种生长于环境二氧化碳浓度或高浓度二氧化碳环境下的不同植物种类之间进行选择时，与取食环境二氧化碳浓度下生长的叶片相比，高浓度二氧化碳环境下雌性对欧洲越桔和湿地越桔的取食量增加，而雄性则减少。我们的研究结果表明，大气中二氧化碳浓度升高明显影响了高山林线两种重要矮灌木的叶片化学性质，导致该系统中最重要的食草昆虫的取食行为、生长和繁殖发生变化。植物与蚱蜢相互作用的变化可能会对高山林线交错带的食草动物压力、群落动态和生态系统稳定性产生重大的长期影响。
