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Annual rainfall does not directly determine the carbon isotope ratio of leaves of Eucalyptus species
Author(s) -
Turner Neil C.,
Schulze ErnstDetlef,
Nicolle Dean,
Schumacher Jens,
Kuhlmann Iris
Publication year - 2008
Publication title -
physiologia plantarum
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.351
H-Index - 146
eISSN - 1399-3054
pISSN - 0031-9317
DOI - 10.1111/j.1399-3054.2007.01027.x
Subject(s) - eucalyptus , isotopes of carbon , nitrogen , range (aeronautics) , isotopes of nitrogen , botany , horticulture , environmental science , biology , total organic carbon , agronomy , zoology , ecology , chemistry , materials science , organic chemistry , composite material
Leaf carbon isotope discrimination (δ 13 C) was widely considered to directly reflect the rainfall environment in which the leaf developed, but recent observations have queried this. The relationship between δ 13 C and rainfall was explored in Eucalyptus species growing along a rainfall gradient in Australia. The leaves of 43 species of Eucalyptus and the closely related Corymbia species produced in 2003 were sampled in September 2004 at 50 sites and grouped into 15 locations along a rainfall gradient in southwest Western Australia. At 24 sites, the same species and same trees were sampled as in a study in September 2003 when leaves produced in 2002 were sampled. The rainfall in 2004 was on average 190 mm (range 135–270 mm) higher at all locations than in 2003. In the leaves sampled in 2004, the mean carbon isotope discrimination (δ 13 C) across the 15 locations decreased 2.9‰ per 1000 mm of rainfall, the specific leaf area (SLA) increased by 2.9 m 2 kg −1 per 1000 mm of rainfall and the nitrogen (N) content decreased by 1.56 g m −2 per 1000 mm of rainfall. In contrast, a comparison between the leaves produced in the drier 2002 year compared with the wetter 2003 year showed that there was a strong correlation (r 2 = 0.85) between the SLA values between years and a trend for higher values with increasing SLA, but the values of δ 13 C were on average only 0.38‰ lower (more negative) at all locations in the wetter year, equivalent to a decrease of 2.0‰ per 1000 mm of rainfall. The results suggest that while there may be constitutive differences in leaf morphology, SLA and N content per unit area, increasing rainfall or cloudiness associated with higher rainfall increases SLA and decreases N content per unit area. We conclude that rainfall does not directly influence δ 13 C, but induces leaf morphological and physiological changes that affect the resultant δ 13 C.