Mechanistic drivers of stem respiration: a modelling exercise across species and seasons

2021 ◽  
Author(s):  
Roberto L. Salomón ◽  
Linus De Roo ◽  
Jacek Oleksyn ◽  
Kathy Steppe
Keyword(s):  
Stem Respiration

A new automated stem CO2 efflux chamber based on industrial ultra-low-cost sensors

2019 ◽  
Author(s):  
Johannes Brändle ◽  
Norbert Kunert
Keyword(s):  
Gas Exchange ◽  
Low Cost ◽  
Climatic Conditions ◽  
Co2 Efflux ◽  
Diurnal Changes ◽  
Lowland Forest ◽  
Stem Respiration ◽  
Stem Co2 Efflux ◽  
Gas Exchange System ◽  
Controlling Processes

Abstract Tree autotrophic respiratory processes, especially stem respiration or stem CO2 efflux (Estem), are important components of the forest carbon budget. Despite the efforts to investigate the controlling processes of Estem in the last years a considerable lack in our knowledge remains on the abiotic and biotic drivers affecting Estem dynamics. It has been strongly advocated that long-term measurements would shed light into those processes. The expensive scientific instruments needed to measure gas exchange has prevented from applying Estem measurements on a larger temporal and spatial scale. Here, we present an automated closed dynamic chamber system based on inexpensive and industrially broadly applied CO2 sensors reducing the costs for the sensing system to a minimum. The CO2 sensor was cross-calibrated with a commonly used gas exchange system in the laboratory and in the field, and we found very good accordance of these sensors. We tested the system under harsh tropical climatic conditions, characterized by heavy tropical rainfall events, extreme humidity, and temperatures, in a moist lowland forest in Malaysia. We recorded Estem of three Dyera costulata trees with our prototype over various days. The variation of Estem was large among the three tree individuals and varied by 7.5-fold. However, clear diurnal changes in Estem were present in all three tree individuals. One tree showed high diurnal variation in Estem and the relationship between Estem and temperature was characterized by a strong hysteresis. The large variations found within one single tree species highlights the importance of continuous measurement to quantify ecosystem carbon fluxes.

scholarly journals Low-cost chamber design for simultaneous CO2 and O2 flux measurements between tree stems and the atmosphere

2021 ◽  
Author(s):  
Juliane Helm ◽  
Henrik Hartmann ◽  
Martin Göbel ◽  
Boaz Hilman ◽  
David Herrera ◽  
...  
Keyword(s):  
Low Cost ◽  
Co2 Flux ◽  
Co2 Efflux ◽  
Stem Respiration ◽  
Ecosystem Carbon ◽  
O2 Concentration ◽  
Flux Measurements ◽  
Stem Co2 Efflux ◽  
Tree Stem

Abstract Tree stem CO2 efflux is an important component of ecosystem carbon fluxes and has been the focus of many studies. While CO2 efflux can easily be measured, a growing number of studies have shown that it is not identical with actual in situ respiration. Complementing measurements of CO2 flux with simultaneous measurements of O2 flux provides an additional proxy for respiration, and the combination of both fluxes can potentially help getting closer to actual measures of respiratory fluxes. To date, however, the technical challenge to measure relatively small changes in O2 concentration against its high atmospheric background has prevented routine O2 measurements in field applications. Here we present a new and low-cost field-tested device for autonomous real-time and quasi-continuous long-term measurements of stem respiration by combining CO2 (NDIR based) and O2 (quenching based) sensors in a tree stem chamber. Our device operates as a cyclic closed system and measures changes in both CO2 and O2 concentration within the chamber over time. The device is battery-powered with a > 1 week power independence and data acquisition is conveniently achieved by an internal logger. Results from both field and laboratory tests document that our sensors provide reproducible measurements of CO2 and O2 exchange fluxes under varying environmental conditions.

scholarly journals Internal respiration of Amazon tree stems greatly exceeds external CO<sub>2</sub> efflux

2012 ◽  
Vol 9 (12) ◽  
pp. 4979-4991 ◽  
Author(s):  
A. Angert ◽  
J. Muhr ◽  
R. Negron Juarez ◽  
W. Alegria Muñoz ◽  
G. Kraemer ◽  
...  
Keyword(s):  
Tropical Trees ◽  
Co2 Efflux ◽  
Water Stream ◽  
New Approach ◽  
Stem Respiration ◽  
Internal Flux ◽  
Stem Co2 Efflux ◽  
Internal Co2 ◽  
Global Carbon ◽  
Net Release

Abstract. Respiration in tree stems is an important component of forest carbon balance. The rate of CO2 efflux from the stem has often been assumed to be a measure of stem respiration. However, recent work in temperate forests has demonstrated that stem CO2 efflux can either overestimate or underestimate respiration rate because of emission or removal of CO2 by transport in xylem water. Here, we studied gas exchange from stems of tropical forest trees using a new approach to better understand respiration in an ecosystem that plays a key role in the global carbon cycle. Our main questions were (1) is internal CO2 transport important in tropical trees, and, if so, (2) does this transport result in net release of CO2 respired in the roots at the stem, or does it cause the opposite effect of net removal of stem-respired CO2? To answer these questions, we measured the ratio of stem CO2 efflux to O2 influx. This ratio, defined here as apparent respiratory quotient (ARQ), is expected to equal 1.0 if carbohydrates are the substrate for respiration, and the net transport of CO2 in the xylem water is negligible. Using a stem chamber approach to quantifying ARQ, we found values of 0.66 ± 0.18. These low ARQ values indicate that a large portion of respired CO2 (~ 35%) is not emitted locally, and is probably transported upward in the stem. ARQ values of 0.21 ± 0.10 were found for the steady-state gas concentration within the stem, sampled by in-stem equilibration probes. These lower values may result from the proximity to the xylem water stream. In contrast, we found ARQ values of 1.00 ± 0.13 for soil respiration. Our results indicate the existence of a considerable internal flux of CO2 in the stems of tropical trees. If the transported CO2 is used in the canopy as a substrate for photosynthesis, it could account for up to 10% of the C fixed by the tree, and perhaps serve as a mechanism that buffers the response of the tree to changing CO2 levels. Our results also indicate, in agreement with previous work, that the widely used CO2 efflux approach for determining stem respiration is unreliable. We demonstrate here a field applicable approach for measuring the O2 uptake rate, which we suggest to be a more appropriate method to estimate stem respiration rates.

Stem respiration increases in CO2-enriched sweetgum trees

2002 ◽  
Vol 155 (2) ◽  
pp. 239-248 ◽  
Author(s):  
Nelson T. Edwards ◽  
Timothy J. Tschaplinski ◽  
Richard J. Norby
Keyword(s):  
Stem Respiration

scholarly journals Temperature Sensitivity in Individual Components of Ecosystem Respiration Increases along the Vertical Gradient of Leaf–Stem–Soil in Three Subtropical Forests

Forests ◽  
2020 ◽  
Vol 11 (2) ◽  
pp. 140
Author(s):  
Yonggang Chi ◽  
Qingpeng Yang ◽  
Lei Zhou ◽  
Ruichang Shen ◽  
Shuxia Zheng ◽  
...  
Keyword(s):  
Loblolly Pine ◽  
Temperature Sensitivity ◽  
Ecosystem Respiration ◽  
Terrestrial Ecosystems ◽  
Vertical Gradient ◽  
Central China ◽  
Masson Pine ◽  
Stem Respiration ◽  
Crucial Parameter ◽  
Process Based Models

Temperature sensitivity (Q10) of ecosystem respiration (ER) is a crucial parameter for predicting the fate of CO2 in terrestrial e cosystems under global warming. Most studies focus their attention in the variation of Q10 in one or two components of ER, but not in the integration or comparison among Q10 in major components of ER. Vertical and seasonal variations in individual components, including leaf respiration, stem respiration and soil respiration, of ER were observed synchronously along the gradient of leaf–stem–soil over a 2 year period in three forest stands dominated by masson pine, loblolly pine and oak, respectively, in a subtropical forest ecosystem of central China. We found that Q10 in individual components of ER increased along the vertical gradient of leaf–stem–soil. The vertical pattern of Q10 in individual components of ER was ascribed to variations of diurnal temperature range (DTR) and activation energy (ΔHa). These results suggest that a vertical pattern of Q10 in individual components of ER along the gradient of leaf–stem–soil should be taken into consideration in process-based models that simulate respiratory carbon flux in terrestrial ecosystems.

scholarly journals Elevated CO2does not affect stem CO2efflux nor stem respiration in a dryEucalyptuswoodland, but it shifts the vertical gradient in xylem [CO2]

2019 ◽  
Vol 42 (7) ◽  
pp. 2151-2164 ◽  
Author(s):  
Roberto L. Salomón ◽  
Kathy Steppe ◽  
Kristine Y. Crous ◽  
Nam Jin Noh ◽  
David S. Ellsworth
Keyword(s):  
Vertical Gradient ◽  
Stem Respiration

scholarly journals TR eSpire – a biophysical TR ee Stem respiration model

2019 ◽  
Vol 225 (5) ◽  
pp. 2214-2230 ◽  
Author(s):  
Roberto L. Salomón ◽  
Linus De Roo ◽  
Jacek Oleksyn ◽  
Dirk J. W. De Pauw ◽  
Kathy Steppe
Keyword(s):  
Stem Respiration ◽  
Respiration Model

scholarly journals Vertical Strata and Stem Carbon Dioxide Efflux in Cycas Trees

Plants ◽  
2020 ◽  
Vol 9 (2) ◽  
pp. 230 ◽  
Author(s):  
Thomas E. Marler ◽  
Murukesan V. Krishnapillai
Keyword(s):  
Carbon Dioxide ◽  
Carbon Cycling ◽  
Sap Flow ◽  
Quadratic Model ◽  
Maintenance Respiration ◽  
Stem Respiration ◽  
Ecosystem Carbon ◽  
Vertical Location ◽  
Carbon Dioxide Efflux ◽  
Cycas Revoluta

Stem respiration is influenced by the vertical location of tree stems, but the influence of vertical location on stem respiration in a representative cycad species has not been determined. We quantified the influence of vertical strata on stem carbon dioxide efflux (Es) for six arborescent Cycas L. species to characterize this component of stem respiration and ecosystem carbon cycling. The influence of strata on Es was remarkably consistent among the species, with a stable baseline flux characterizing the full mid-strata of the pachycaulous stems and an increase in Es at the lowest and highest strata. The mid-strata flux ranged from 1.8 μmol·m−2·s−1 for Cycas micronesica K.D. Hill to 3.5 μmol·m−2·s−1 for Cycas revoluta Thunb. For all species, Es increased about 30% at the lowest stratum and about 80% at the highest stratum. A significant quadratic model adequately described the Es patterns for all six species. The increase of Es at the lowest stratum was consistent with the influence of root-respired carbon dioxide entering the stem via sap flow, then contributing to Es via radial conductance to the stem surface. The substantial increase in Es at the highest stratum is likely a result of the growth and maintenance respiration of the massive cycad primary thickening meristem that constructs the unique pachycaulous cycad stem.

scholarly journals Comparison of CO<sub>2</sub> and O<sub>2</sub> fluxes demonstrate retention of respired CO<sub>2</sub> in tree stems from a range of tree species

2019 ◽  
Vol 16 (1) ◽  
pp. 177-191 ◽  
Author(s):  
Boaz Hilman ◽  
Jan Muhr ◽  
Susan E. Trumbore ◽  
Norbert Kunert ◽  
Mariah S. Carbone ◽  
...  
Keyword(s):  
Tree Species ◽  
Sap Flow ◽  
Xylem Sap ◽  
Co2 Efflux ◽  
Forest Trees ◽  
O2 Uptake ◽  
Stem Respiration ◽  
Low Solubility ◽  
Main Substrate

Abstract. 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 nine 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 refixation of respired CO2 in biosynthesis reactions as possible mechanism for low ARQ values.

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