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The role of effective leaf mixing length in the relationship between the δ 18 O of stem cellulose and source water across a salinity gradient
Author(s) -
ELLSWORTH PATRICIA V.,
ELLSWORTH PATRICK Z.,
ANDERSON WILLIAM T.,
STERNBERG LEONEL S. L.
Publication year - 2013
Publication title -
plant, cell and environment
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.646
H-Index - 200
eISSN - 1365-3040
pISSN - 0140-7791
DOI - 10.1111/j.1365-3040.2012.02562.x
Subject(s) - transect , mangrove , salinity , fractionation , cellulose , botany , isotopes of oxygen , biology , chemistry , ecology , chromatography , nuclear chemistry , biochemistry
Previous mangrove tree ring studies attempted, unsuccessfully, to relate the δ 18 O of trunk cellulose ( δ 18 O CELL ) to the δ 18 O of source water ( δ 18 O SW ). Here, we tested whether biochemical fractionation associated with one of the oxygen in the cellulose glucose moiety or variation in leaf water oxygen isotope fractionation (Δ LW ) can interfere with the δ 18 O SW signal as it is recorded in the δ 18 O CELL of mangrove (saltwater) and hammock (freshwater) plants. We selected two transects experiencing a salinity gradient, located in the Florida Keys, USA. The δ 18 O CELL throughout both transects did not show the pattern expected based on that of the δ 18 O SW . We found that in one of the transects, biochemical fractionation interfered with the δ 18 O SW signal, while in the other transect Δ LW differed between mangrove and hammock plants. Observed differences in Δ LW between mangroves and hammocks were caused by a longer effective leaf mixing length (L) of the water pathway in mangrove leaves compared to those of hammock leaves. Changes in L could have caused the δ 18 O CELL to record not only variations in the δ 18 O SW but also in Δ LW making it impossible to isolate the δ 18 O SW signal.