Importance of short-term dynamics in carbon isotope ratios of ecosystem respiration (delta13C(R)) in a Mediterranean oak woodland and linkage to environmental factors.
Temporal dynamics in carbon isotope ratios of ecosystem respiration (delta13C(R)) were evaluated on hourly, daily and annual timescales in a Mediterranean woodland. Emphasis was given to the periods of transition from wet to dry season and vice versa, when the system turns from a net carbon sink to a source. The constancy of nocturnal delta13C(R) was tested. The relationship between delta13C(R) (determined through Keeling plots) and environmental factors was evaluated through time-lag analysis. Delta13C(R) exhibited high annual variation (> 7). During the transition periods, delta13C(R) correlated significantly with factors influencing photosynthetic discrimination, soil respiration, and whole-canopy conductance. Time-lags differed between below- and above-ground variables, and between seasons. A shift in regression parameters with environmental factors indicated seasonal differences in ecosystem responsiveness (e.g. temperature acclimation). Delta13C(R) exhibited substantial nocturnal enrichment (> 4) from dusk to dawn. These data indicate pronounced short-term dynamics in delta13C(R) at hourly to daily timescales and a modulated response to environmental drivers. Substantial short-term changes in nocturnal delta13C(R) may have important implications for the sampling protocols of nocturnal Keeling plots.
Werner
Christiane
C
Exp. and Systems Ecology, University of Bielefeld, Universitätsstr. 25, D-33615 Bielefeld, Germany. c.werner@uni-bielefeld.de
Unger
Stephan
S
Pereira
João S
JS
Maia
Rodrigo
R
David
Teresa S
TS
Kurz-Besson
Cathy
C
David
Jorge S
JS
Máguas
Cristina
C
D002245:Carbon Dioxide / Q000378:metabolism*; D002247:Carbon Isotopes; D002940:Circadian Rhythm; D017753:Ecosystem; D019083:Mediterranean Region; D029963:Quercus / Q000378:metabolism*; D012621:Seasons; D013997:Time Factors; D014197:Trees / Q000378:metabolism*
D002247:Carbon Isotopes; D002245:Carbon Dioxide