Xylem and soil CO2 fluxes in a Quercus pyrenaica Willd. coppice: root respiration increases with clonal size

Salomón, Roberto L.; Valbuena‐Carabaña, María; Rodríguez‐Calcerrada, Jesús; Aubrey, Doug P.; McGuire, MaryAnne; Teskey, Robert O.; Gil, Luis; González-Doncel, Inés

doi:10.1007/s13595-015-0504-7

Cited by 21 publications

(12 citation statements)

References 64 publications

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“…deltoides plantation, F T at the stem base even doubled the amount of soil CO 2 efflux originated from root respiration (Aubrey & Teskey, ). Likewise, substantial xylem [CO 2 ] variability observed at the stem base of Platanus occidentalis trees was associated to stem size with potentially bigger roots (Teskey & McGuire, ), and F T at the stem base scaled up with soil CO 2 efflux in multistemmed oak trees with larger root systems (Salomón et al, ). Here, higher xylem [CO 2 ] measured closer to the soil level suggests greater root respiration in eCO 2 rings.…”

Section: Discussionmentioning

confidence: 99%

Elevated CO₂ does not affect stem CO₂ efflux nor stem respiration in a dry Eucalyptus woodland, but it shifts the vertical gradient in xylem [CO₂]

Salomón

Steppe

Crous

et al. 2019

Plant Cell & Environment

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To quantify stem respiration (RS) under elevated CO2 (eCO2), stem CO2 efflux (EA) and CO2 flux through the xylem (FT) should be accounted for, because part of respired CO2 is transported upwards with the sap solution. However, previous studies have used EA as a proxy of RS, which could lead to equivocal conclusions. Here, to test the effect of eCO2 on RS, both EA and FT were measured in a free‐air CO2 enrichment experiment located in a mature Eucalyptus native forest. Drought stress substantially reduced EA and RS, which were unaffected by eCO2, likely as a consequence of its neutral effect on stem growth in this phosphorus‐limited site. However, xylem CO2 concentration measured near the stem base was higher under eCO2, and decreased along the stem resulting in a negative contribution of FT to RS, whereas the contribution of FT to RS under ambient CO2 was positive. Negative FT indicates net efflux of CO2 respired below the monitored stem segment, likely coming from the roots. Our results highlight the role of nutrient availability on the dependency of RS on eCO2 and suggest stimulated root respiration under eCO2 that may shift vertical gradients in xylem [CO2] confounding the interpretation of EA measurements.

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Section: Discussionmentioning

confidence: 99%

Elevated CO₂ does not affect stem CO₂ efflux nor stem respiration in a dry Eucalyptus woodland, but it shifts the vertical gradient in xylem [CO₂]

Salomón

Steppe

Crous

et al. 2019

Plant Cell & Environment

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“…Moreover, the microbial respiration could increase around vigorous trees as a result of higher root exudation rates and leaf and fine root litter supply to the soil [14]. In support of this reasoning it has been observed that variables related with photosynthetic C uptake, such as the leaf area index, sap flow, tree size, or tree proximity to and live tree basal area around R s sampling locations are positively related to R s [11,[15][16][17][18][19][20]. Nevertheless, R s can be relatively homeostatic across successional stages or after perturbations [8,[21][22][23].…”

Section: Introductionmentioning

confidence: 83%

Regeneration in the Understory of Declining Overstory Trees Contributes to Soil Respiration Homeostasis along Succession in a Sub-Mediterranean Beech Forest

Rodríguez‐Calcerrada

Salomón

Barba

et al. 2019

Forests

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Research Highlights: Tree decline can alter soil carbon cycling, given the close relationship between primary production and the activity of roots and soil microbes. Background and Objectives: We studied how tree decline associated to old age and accelerated by land-use change and increased drought in the last decades, affects soil properties and soil respiration (Rs). Materials and Methods: We measured Rs over two years around centennial European beech (Fagus sylvatica L.) trees representing a gradient of decline in a sub-Mediterranean forest stand, where the number of centennial beech trees has decreased by 54% in the last century. Four replicate plots were established around trees (i) with no apparent crown dieback, (ii) less than 40% crown dieback, (iii) more than 50% crown dieback, and (iv) dead. Results: Temporal variations in Rs were controlled by soil temperature (Ts) and soil water content (SWC). The increase in Rs with Ts depended on SWC. The temperature-normalized Rs exhibited a parabolic relationship with SWC, suggesting a reduced root and microbial respiration associated to drought and waterlogging. The response of Rs to SWC did not vary among tree-decline classes. However, the sensitivity of Rs to Ts was higher around vigorous trees than around those with early symptoms of decline. Spatial variations in Rs were governed by soil carbon to nitrogen ratio, which had a negative effect on Rs, and SWC during summer, when drier plots had lower Rs than wetter plots. These variations were independent of the tree vigor. The basal area of recruits, which was three times (although non-significantly) higher under declining and dead trees than under vigorous trees, had a positive effect on Rs. However, the mean Rs did not change among tree-decline classes. These results indicate that Rs and related soil physico-chemical variables are resilient to the decline and death of dominant centennial trees. Conclusions: The development of advanced regeneration as overstory beech trees decline and die contribute to the Rs homeostasis along forest succession.

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“…Stem CO 2 flux is typically composed of respiration from the stem. However, it has been found that passive diffusion of CO 2 out of the stem from water in the xylem that is being transported from the roots to the shoots, can contribute to the stem CO 2 flux as well [48]. The CO 2 concentration in the soil pores is high, typically several thousand ppm, which leads to CO 2 being dissolved in the soil water [49][50][51].…”

Section: Overall δ 13 C Values Of the Co 2 Fluxes From Intact Soils mentioning

confidence: 99%

Combining a Quantum Cascade Laser Spectrometer with an Automated Closed-Chamber System for δ13C Measurements of Forest Soil, Tree Stem and Tree Root CO2 Fluxes

Brændholt

Ibrom

Larsen

et al. 2019

Forests

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Recent advances in laser spectroscopy have allowed for real-time measurements of the 13C/12C isotopic ratio in CO2, thereby providing new ways to investigate carbon cycling in natural ecosystems. In this study, we combined an Aerodyne quantum cascade laser spectrometer for CO2 isotopes with a LI-COR LI-8100A/8150 automated chamber system to measure the δ13C of CO2 during automated closed-chamber measurements. The isotopic composition of the CO2 flux was determined for each chamber measurement by applying the Keeling plot method. We found that the δ13C measured by the laser spectrometer was influenced by water vapour and CO2 concentration of the sample air and we developed a method to correct for these effects to yield accurate measurements of δ13C. Overall, correcting for the CO2 concentration increased the δ13C determined from the Keeling plots by 3.4‰ compared to 2.1‰ for the water vapour correction. We used the combined system to measure δ13C of the CO2 fluxes automatically every two hours from intact soil, trenched soil, tree stems and coarse roots during a two-month campaign in a Danish beech forest. The mean δ13C was −29.8 ± 0.32‰ for the intact soil plots, which was similar to the mean δ13C of −29.8 ± 1.2‰ for the trenched soil plots. The lowest δ13C was found for the root plots with a mean of −32.6 ± 0.78‰. The mean δ13C of the stems was −30.2 ± 0.74‰, similar to the mean δ13C of the soil plots. In conclusion, the study showed the potential of using a quantum cascade laser spectrometer to measure δ13C of CO2 during automated closed-chamber measurements, thereby allowing for measurements of isotopic ecosystem CO2 fluxes at a high temporal resolution. It also highlighted the importance of proper correction for cross-sensitivity with water vapour and CO2 concentration of the sample air to get accurate measurements of δ13C.

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Xylem and soil CO2 fluxes in a Quercus pyrenaica Willd. coppice: root respiration increases with clonal size

Abstract: Abstract• Key message Xylem and soil CO 2 fluxes in coppiced oak forests increase with clonal size, suggesting larger expenditures of energy for root respiration.

Cited by 21 publications

References 64 publications

Elevated CO₂ does not affect stem CO₂ efflux nor stem respiration in a dry Eucalyptus woodland, but it shifts the vertical gradient in xylem [CO₂]

Elevated CO₂ does not affect stem CO₂ efflux nor stem respiration in a dry Eucalyptus woodland, but it shifts the vertical gradient in xylem [CO₂]

Regeneration in the Understory of Declining Overstory Trees Contributes to Soil Respiration Homeostasis along Succession in a Sub-Mediterranean Beech Forest

Combining a Quantum Cascade Laser Spectrometer with an Automated Closed-Chamber System for δ13C Measurements of Forest Soil, Tree Stem and Tree Root CO2 Fluxes

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Xylem and soil CO2 fluxes in a Quercus pyrenaica Willd. coppice: root respiration increases with clonal size

Abstract: Abstract• Key message Xylem and soil CO 2 fluxes in coppiced oak forests increase with clonal size, suggesting larger expenditures of energy for root respiration.

Cited by 21 publications

References 64 publications

Elevated CO2 does not affect stem CO2 efflux nor stem respiration in a dry Eucalyptus woodland, but it shifts the vertical gradient in xylem [CO2]

Elevated CO2 does not affect stem CO2 efflux nor stem respiration in a dry Eucalyptus woodland, but it shifts the vertical gradient in xylem [CO2]

Regeneration in the Understory of Declining Overstory Trees Contributes to Soil Respiration Homeostasis along Succession in a Sub-Mediterranean Beech Forest

Combining a Quantum Cascade Laser Spectrometer with an Automated Closed-Chamber System for δ13C Measurements of Forest Soil, Tree Stem and Tree Root CO2 Fluxes

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Elevated CO₂ does not affect stem CO₂ efflux nor stem respiration in a dry Eucalyptus woodland, but it shifts the vertical gradient in xylem [CO₂]

Elevated CO₂ does not affect stem CO₂ efflux nor stem respiration in a dry Eucalyptus woodland, but it shifts the vertical gradient in xylem [CO₂]