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Ameliorating effect of UV‐B radiation on the response of Norway spruce and Scots pine to ambient ozone concentrations
Author(s) -
Schnitzler JörgPeter,
Langebartels Christian,
Heller Werner,
Liu Jinchen,
Lippert Michael,
Döhring Thorsten,
Bahnweg Günther,
Sandermann Heinrich
Publication year - 1999
Publication title -
global change biology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 4.146
H-Index - 255
eISSN - 1365-2486
pISSN - 1354-1013
DOI - 10.1046/j.1365-2486.1998.00208.x
Subject(s) - scots pine , ozone , picea abies , photosynthesis , horticulture , growing season , botany , environmental chemistry , environmental science , altitude (triangle) , chemistry , pinus <genus> , biology , geometry , mathematics , organic chemistry
Elevated levels of both ozone and UV‐B radiation are typical for high‐altitude sites. Few studies have investigated their possible interaction on plants. This study reports interactive effects of O 3 and UV‐B radiation in four‐year‐old Norway spruce and Scots pine trees. The trees were cultivated in controlled environmental facilities under simulated climatic conditions recorded on Mt Wank, an Alpine mountain in Bavaria, and were exposed for one growing season to simulated ambient or twice‐ambient ozone regimes at either near ambient or near zero UV‐B radiation levels. Chlorotic mottling and yellowing of current year needles became obvious under twice‐ambient O 3 in both species at the onset of a high ozone episode in July. Development of chlorotic mottling in relation to accumulated ozone concentrations over a threshold of 40 nL L –1 was more pronounced with near zero rather than ambient UV‐B radiation levels. In Norway spruce, photosynthetic parameters at ambient CO 2 concentration, measured at the end of the experiment, were reduced in trees cultivated under twice‐ambient O 3 , irrespective of the UV‐B treatment. Effects on photosynthetic capacity and carboxylation efficiency were restricted to trees exposed to near zero levels of UV‐B radiation, and twice‐ambient O 3 . The data indicate that UV‐B radiation, applied together with O 3 , ameliorates the detrimental effects of O 3 . The data also demonstrate that foliar symptoms develop more rapidly in Scots pine than in Norway spruce at higher accumulated ozone concentrations.Symbols and abbreviations: LSD, least significant difference; PAS300, UV‐B irradiance weighted according to the plant action spectrum of Green et al . (1974) normalized at 300 (nm); AOT40, (AOT = accumulated over threshold) reflects the sum of hourly ozone concentrations above 40 nL L –1 during daylight hours (> 50 Wm –2 ) (Kärenlampi & Skärby 1996); A 350 , net photosynthesis at ambient CO 2 ; G 350 , stomatal conductance for water vapour at ambient CO 2 ; A 2500 , net photosynthesis at saturating CO 2 (maximal potential photosynthetic activity); CE, carboxylation efficiency; ROS, reactive oxygen species; RuBP, ribulose 1,5‐bisphosphate; Rubisco, ribulose 1,5‐bisphosphate carboxylase/oxygenase; GLM, general linear model.