תפריט נגישות
ניגודיות עדינהניגודיות גבוהה
מונוכרום
הדגשת קישורים
חסימת אנימציה
פונט קריא
סגור
איפוס הגדרות נגישות
להורדת מודול נגישות חינם תפריט נגישותניגודיות עדינהניגודיות גבוההמונוכרוםהדגשת קישוריםחסימת אנימציהפונט קריאסגוראיפוס הגדרות נגישותלהורדת מודול נגישות חינםTal Weiner, Alon Angert, Boaz Hilman - The Fredy and Nadine Herrmann Institute of Earth Sciences, The Hebrew University of Jerusalem
Jan Muhr, Susan E. Trumbore - Department of Biogeochemical Processes, Max-Planck Institute for Biogeochemistry, Jena, 07745, Germany
Mariah S. Carbone - Center for Ecosystem Science and Society, Northern Arizona University, Flagstaff, AZ 86011, USA. Arnaud Carrara - Instituto Universitario Fundación Centro de Estudios Ambientales del Mediterráneo (CEAM-UMH), Paterna, 46980, Spain
José M. Grünzweig - Robert H. Smith Institute of Plant Sciences and Genetics in Agriculture, Robert H. Smith Faculty of Agriculture, Food and Environment, The Hebrew University of Jerusalem, Rehovot
S. Joseph Wright - Smithsonian Tropical Research Institute, Balboa, Apartado 0843-03092, Panama. Gerardo Moreno - Institute for Dehesa Research, University of Extremadura, Plasencia, 10600, Spain
Oscar Pérez-Priego, Mirco Migliavacca - Department of Biogeochemical Integration, Max Planck Institute for Biogeochemistry, Jena, 07745, Germany
the ratio of CO2 efflux to O2 influx (ARQ, apparent respiratory quotient) in tree stems is expected to be 1.0 for carbohydrates, the main substrate supporting stem respiration. In previous studies of stem fluxes, ARQ values below 1.0 were observed and hypothesized to indicate retention of respired carbon within the stem. Here, we demonstrate that stem ARQ<1.0 values are common across 85 tropical, temperate, and Mediterranean forest trees from 9 different species. Mean ARQ values per species per site ranged from 0.39 to 0.78, with an overall mean of 0.59. Assuming that O2 uptake provides a measure of in situ stem respiration (due to the low solubility of O2), the overall mean indicates that on average 41% of CO2 respired in stems is not emitted from the local stem surface. The instantaneous ARQ did not vary with sap flow. ARQ values of incubated stem cores were similar to those measured in stem chambers on intact trees. We therefore conclude that dissolution of CO2 in the xylem sap and transport away from the site of respiration cannot explain the low ARQ values. We suggest to examine refixation of respired CO2 in biosynthesis reactions as possible mechanism for low ARQ values.
Manuscript under review for journal Biogeosciences
Tal Weiner, Alon Angert, Boaz Hilman - The Fredy and Nadine Herrmann Institute of Earth Sciences, The Hebrew University of Jerusalem
Jan Muhr, Susan E. Trumbore - Department of Biogeochemical Processes, Max-Planck Institute for Biogeochemistry, Jena, 07745, Germany
Mariah S. Carbone - Center for Ecosystem Science and Society, Northern Arizona University, Flagstaff, AZ 86011, USA. Arnaud Carrara - Instituto Universitario Fundación Centro de Estudios Ambientales del Mediterráneo (CEAM-UMH), Paterna, 46980, Spain
José M. Grünzweig - Robert H. Smith Institute of Plant Sciences and Genetics in Agriculture, Robert H. Smith Faculty of Agriculture, Food and Environment, The Hebrew University of Jerusalem, Rehovot
S. Joseph Wright - Smithsonian Tropical Research Institute, Balboa, Apartado 0843-03092, Panama. Gerardo Moreno - Institute for Dehesa Research, University of Extremadura, Plasencia, 10600, Spain
Oscar Pérez-Priego, Mirco Migliavacca - Department of Biogeochemical Integration, Max Planck Institute for Biogeochemistry, Jena, 07745, Germany
the ratio of CO2 efflux to O2 influx (ARQ, apparent respiratory quotient) in tree stems is expected to be 1.0 for carbohydrates, the main substrate supporting stem respiration. In previous studies of stem fluxes, ARQ values below 1.0 were observed and hypothesized to indicate retention of respired carbon within the stem. Here, we demonstrate that stem ARQ<1.0 values are common across 85 tropical, temperate, and Mediterranean forest trees from 9 different species. Mean ARQ values per species per site ranged from 0.39 to 0.78, with an overall mean of 0.59. Assuming that O2 uptake provides a measure of in situ stem respiration (due to the low solubility of O2), the overall mean indicates that on average 41% of CO2 respired in stems is not emitted from the local stem surface. The instantaneous ARQ did not vary with sap flow. ARQ values of incubated stem cores were similar to those measured in stem chambers on intact trees. We therefore conclude that dissolution of CO2 in the xylem sap and transport away from the site of respiration cannot explain the low ARQ values. We suggest to examine refixation of respired CO2 in biosynthesis reactions as possible mechanism for low ARQ values.
Manuscript under review for journal Biogeosciences
