Bassin Seraina, Werner Roland A, Sörgel Karin, Volk Matthias, Buchmann Nina, Fuhrer Jürg
Air Pollution and Climate Group, Agroscope Research Station ART, Reckenholzstrasse 191, 8046, Zurich, Switzerland.
Oecologia. 2009 Jan;158(4):747-56. doi: 10.1007/s00442-008-1191-y. Epub 2008 Oct 31.
Tropospheric O(3) and deposition of reactive N threaten the composition and function of natural and semi-natural vegetation even in remote regions. However, little is known about effects of these pollutants individually or in combination on plant species in alpine habitats. We analyzed 11 frequent plant species of a subalpine Geo-Montani-Nardetum pasture exposed at 2,000 m a.s.l. in the Swiss Alps during 3 years using a factorial free-air exposure system with three concentrations of O(3) and five rates of N application. The aim was to detect subtle effects on leaf chlorophyll and N concentrations, leaf weight, specific leaf area (SLA), and delta(18)O and delta(13)C as proxies for gas exchange. We expected that the species' responsiveness to O(3) and N would be related to their functional traits and that N-induced changes in these traits would modify the species' response to O(3) via increased growth and higher leaf conductance (g (s)). Most species reacted to N supply with the accumulation of N and chlorophyll, but with no change in SLA, g (s), and growth, except Carex sempervirens which showed increased water use efficiency and leaf weight. Elevated O(3) reduced g ( s ) in most species, but this was not related to a reduction in leaf weight, which was recorded in half of the species. Contrary to our expectation, the magnitude of the response to both O(3) and N was not related to species-specific traits such as SLA or g (s). No pronounced O(3) x N interactions were observed. In conclusion, since for most species neither N nor gas exchange limited growth, their short-term response to O(3) and N and to their combination was small. O(3) x N interactive effects are expected to be more pronounced in habitats where species are more responsive to N due to favorable growth conditions in terms of nutrient availability and temperature.
对流层中的臭氧（O₃）和活性氮沉降甚至在偏远地区也会威胁到天然和半天然植被的组成与功能。然而，对于这些污染物单独或联合作用于高山栖息地植物物种的影响，我们却知之甚少。我们利用一个析因自由空气暴露系统，设置了三种臭氧浓度和五种施氮速率，对瑞士阿尔卑斯山海拔2000米处亚高山地杨梅-山地早熟禾群落草场上的11种常见植物进行了为期3年的分析。目的是检测对叶片叶绿素和氮浓度、叶重、比叶面积（SLA）以及作为气体交换指标的δ¹⁸O和δ¹³C的细微影响。我们预期物种对臭氧和氮的响应会与其功能性状相关，并且氮诱导的这些性状变化会通过增加生长和提高叶片导度（gs）来改变物种对臭氧的响应。大多数物种对氮供应的反应是氮和叶绿素的积累，但比叶面积、叶片导度和生长没有变化，只有青绿苔草表现出水分利用效率和叶重增加。臭氧浓度升高使大多数物种的叶片导度降低，但这与半数物种记录到的叶重降低无关。与我们的预期相反，对臭氧和氮的响应程度与比叶面积或叶片导度等物种特异性性状无关。未观察到明显的臭氧×氮交互作用。总之，由于大多数物种的生长既不受氮限制也不受气体交换限制，它们对臭氧、氮及其组合的短期响应较小。在因养分有效性和温度等生长条件有利而使物种对氮更敏感的栖息地，预计臭氧×氮交互作用会更显著。
