Hättenschwiler Stephan, Schafellner Christa
Botanisches Institut, Universität Basel, Schönbeinstrasse 6, CH-4056 Basel, Switzerland e-mail:
Institute for Forest Entomology, Forest Pathology and Forest Protection, Universität für Bodenkultur (BOKU), Hasenauerstrasse 38, A-1190 Vienna, Austria, , , , , , AT.
Oecologia. 1999 Feb;118(2):210-217. doi: 10.1007/s004420050720.
The effects of elevated atmospheric CO and increased wet N deposition on leaf quality and insect herbivory were evaluated in nine model ecosystems composed of 7-year-old spruce trees (Picea abies) and three understorey species established on natural forest soil. Each model ecosystem was grown in a simulated montane climate, and was exposed to one of three CO concentrations (280, 420, and 560 μl l), and to one of three levels of N deposition (0, 30, and 90 kg ha year) for 3 years. In the 3rd year of the experiment second to third instars of the nun moth (Lymantria monacha) were allowed to feed directly on current-year needles of top canopy branches of each tree for 12 days. Specific leaf area (SLA), water content, and N concentration decreased in needles exposed to elevated CO, whereas the concentrations of starch, condensed tannins, and total phenolics increased. Increased N deposition had no significant effect on SLA, and water content, but the concentrations of starch, condensed tannins, and total phenolics decreased, and sugar and N concentrations increased. Despite higher relative consumption rates (RCRs) larvae consumed 33% less N per unit larval biomass and per day at the two high CO treatments, compared to those feeding on 280 μl l-needles, but they maintained similar N accumulation rates due to increased N utilization efficiencies (NUE). However, over the 12-day experimental period larvae gained less N overall and reached a 35% lower biomass in the two high-CO treatments compared to those at 280 μl l. The effects of increased N deposition on needle quality and insect performance were generally opposite to those of CO enrichment, but were lower in magnitude. We conclude that altered needle quality in response to elevated CO will impair the growth and development of L. monacha larvae. Increasing N deposition may mitigate these effects, which could lead to altered insect herbivore distributions depending on regional patterns of N deposition.
在由7年生云杉树（欧洲云杉）和三种林下植物组成的九个模型生态系统中，评估了大气二氧化碳浓度升高和湿态氮沉降增加对叶片质量和昆虫食草作用的影响。这些生态系统建立在天然森林土壤上。每个模型生态系统在模拟山地气候中生长，并在三年时间里暴露于三种二氧化碳浓度（280、420和560 μl l）之一以及三种氮沉降水平（0、30和90 kg ha 年）之一。在实验的第三年，允许舞毒蛾（Lymantria monacha）的二至三龄幼虫直接取食每棵树顶冠层当年生针叶12天。暴露于高浓度二氧化碳的针叶中，比叶面积（SLA）、含水量和氮浓度降低，而淀粉、缩合单宁和总酚类物质的浓度增加。增加氮沉降对SLA和含水量没有显著影响，但淀粉、缩合单宁和总酚类物质的浓度降低，糖和氮浓度增加。尽管相对取食率（RCRs）较高，但与取食280 μl l针叶的幼虫相比，在两种高二氧化碳处理下，幼虫每单位幼虫生物量和每天消耗的氮减少33%，但由于氮利用效率（NUE）提高，它们保持了相似的氮积累率。然而，在12天的实验期内，与280 μl l处理相比，两种高二氧化碳处理下的幼虫总体上获得的氮较少，生物量低35%。增加氮沉降对针叶质量和昆虫表现的影响通常与二氧化碳浓度升高的影响相反，但程度较低。我们得出结论，响应高浓度二氧化碳而改变的针叶质量将损害舞毒蛾幼虫的生长和发育。增加氮沉降可能会减轻这些影响，这可能导致食草昆虫分布的改变，具体取决于区域氮沉降模式。
