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Non‐climatic variations in the oxygen isotopic compositions of plants
Author(s) -
WANG XUEFENG.,
YAKIR DAN.,
AVISHAI MICHAEL
Publication year - 1998
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.1365-2486.1998.00197.x
Subject(s) - evaporation , environmental science , meteoric water , chemical composition , environmental chemistry , atmospheric sciences , botany , chemistry , stable isotope ratio , biology , geology , physics , quantum mechanics , organic chemistry , thermodynamics
The 18 O content of leaf water strongly influences the 18 O contents of atmospheric CO 2 and O 2 . The 18 O signatures of these atmospheric gases, in turn, emerge as important indicators of large‐scale gas exchange processes. Better understanding of the factors that influence the isotopic composition of leaf water is still required, however, for the quantitative utilization of these tracers. The 18 O enrichment of leaf water relative to local meteoric water, is known to reflect climatic conditions. Less is known about the extent variations in the 18 O content of leaf water are influenced by nonclimatic, species‐specific characteristics. In a collection of 90 plant species from all continents grown under the same climatic conditions in the Jerusalem Botanical Garden we observed variations of about 9‰ in the δ 18 O values of stem water, δ s , and of about 14‰ in the mid‐day δ 18 O enrichment of bulk leaf water, δ LW –δ s . Differences between δ 18 O values predicted by a conventional evaporation model, δ M , and δ LW ranged between – 3.3‰ and + 11.8‰. The δ 18 O values of water in the chloroplasts (δ ch ) in leaves of 10 selected plants were estimated from on‐line CO 2 discrimination measurements. Although much uncertainty is still involved in these estimates, the results indicated that δ ch can significantly deviate from δ M in species with high leaf peclet number. The δ 18 O values of bulk leaf water significantly correlated with δ 18 O values of leaf cellulose (directly) and with instantaneous water use efficiency (A/E, inversely). Differences in isotopic characteristics among conventionally defined vegetation types were not significant, except for conifers that significantly differed from shrubs in δ 18 O and δ 13 C values of cellulose and in their peclet numbers, and from deciduous woodland species in their δ 18 O and δ 13 C values of cellulose. The results indicated that predictions of the δ 18 O values of leaf water (δ LW , δ M and δ ch ) could be improved by considering plant species‐specific characteristics.