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Importance of short‐term dynamics in carbon isotope ratios of ecosystem respiration (δ 13 C R ) in a Mediterranean oak woodland and linkage to environmental factors
Author(s) -
Werner Christiane,
Unger Stephan,
Pereira João S.,
Maia Rodrigo,
David Teresa S.,
KurzBesson Cathy,
David Jorge S.,
Máguas Cristina
Publication year - 2006
Publication title -
new phytologist
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 3.742
H-Index - 244
eISSN - 1469-8137
pISSN - 0028-646X
DOI - 10.1111/j.1469-8137.2006.01836.x
Subject(s) - ecosystem , atmospheric sciences , mediterranean climate , environmental science , isotopes of carbon , nocturnal , ecology , ecosystem respiration , respiration , carbon sink , carbon cycle , climate change , eddy covariance , biology , botany , physics , total organic carbon
Summary• Temporal dynamics in carbon isotope ratios of ecosystem respiration (δ 13 C 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 δ 13 C R was tested. • The relationship between δ 13 C R (determined through Keeling plots) and environmental factors was evaluated through time‐lag analysis. • δ 13 C R exhibited high annual variation (> 7). During the transition periods, δ 13 C 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). δ 13 C R exhibited substantial nocturnal enrichment (> 4) from dusk to dawn. • These data indicate pronounced short‐term dynamics in δ 13 C R at hourly to daily timescales and a modulated response to environmental drivers. Substantial short‐term changes in nocturnal δ 13 C R may have important implications for the sampling protocols of nocturnal Keeling plots.