Soil CO&amp;lt;sub&amp;gt;2&amp;lt;/sub&amp;gt; efflux in an old-growth southern conifer forest (&amp;lt;i&amp;gt;Agathis australis&amp;lt;/i&amp;gt;) – magnitude, components and controls

Schwendenmann, Luitgard; Macinnis-Ng, Cate

doi:10.5194/soil-2-403-2016

Cited by 14 publications

(6 citation statements)

References 111 publications

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“…We also detected significant variation among individual root-zone F CO2 estimates, both before and after rainfall. Temperature-corrected F CO2 increased significantly with tree size, consistent with prior studies [25][26][27][28][29][30]; however, this pattern was only detected for post-precipitation F CO2 . We did not find any trend with tree health indicators (either recent tree growth increment or crown transparency), suggesting that the size-dependent pattern in F CO2 is not related to tree senescence.…”

Section: Discussionsupporting

confidence: 89%

“…A number of recent studies have documented detectable local effects of tree proximity and even tree species on F CO2 [3,[22][23][24], but the hypothetical mechanisms behind these effects are numerous and remain poorly resolved. Studies have also described effects of tree size on F CO2 in forest ecosystems, generally finding higher F CO2 in the immediate neighborhood of larger trees [25][26][27][28][29][30]. However, counterexamples exist [10,31], and several chrono sequence studies have found reduced F CO2 with stand age in even-aged plantations [32,33], or no consistent relationship [34].…”

Section: Introductionmentioning

confidence: 99%

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Linking Soil CO2 Efflux to Individual Trees: Size-Dependent Variation and the Importance of the Birch Effect

Schurman

Thomas

2021

Soil Systems

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Soil CO2 efflux (FCO2) is a major component of the terrestrial carbon (C) cycle but challenges in explaining local variability hamper efforts to link broad-scale fluxes to their biotic drivers. Trees are the dominant C source for forest soils, so linking tree properties to FCO2 could open new avenues to study plant-soil feedbacks and facilitate scaling; furthermore, FCO2 responds dynamically to meteorological conditions, complicating predictions of total FCO2 and forest C balance. We tested for proximity effects of individual Acer saccharum Marsh. trees on FCO2, comparing FCO2 within 1 m of mature stems to background fluxes before and after an intense rainfall event. Wetting significantly increased background FCO2 (6.4 ± 0.3 vs. 8.6 ± 0.6 s.e. μmol CO2 m−2s−1), with a much larger enhancement near tree stems (6.3 ± 0.3 vs. 10.8 ± 0.4 μmol CO2 m−2s−1). FCO2 varied significantly among individual trees and post-rain values increased with tree diameter (with a slope of 0.058 μmol CO2 m−2s−1cm−1). Post-wetting amplification of FCO2 (the ‘Birch effect’) in root zones often results from the improved mobility of labile carbohydrates and further metabolization of recalcitrant organic matter, which may both occur at higher densities near larger trees. Our results indicate that plant-soil feedbacks change through tree ontogeny and provide evidence for a novel link between whole-system carbon fluxes and forest structure.

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Section: Discussionsupporting

confidence: 89%

Section: Introductionmentioning

confidence: 99%

Linking Soil CO2 Efflux to Individual Trees: Size-Dependent Variation and the Importance of the Birch Effect

Schurman

Thomas

2021

Soil Systems

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“…Unlike other large C fluxes such as net primary production, net ecosystem exchange, and gross primary production, R s cannot be measured, even indirectly, at scales larger than a few square meters (Bond-Lamberty et al, 2016). Though global-scale R s varies between vegetation types and biomes (Raich et al, 2002;Raich and Schlesinger, 1992), and responds to disturbances such as land use and climate changes (Hursh et al, 2017;Schlesinger and Andrews, 2000), it is uncertain how these patterns arise from localscale variability, limiting our ability to robustly scale the process.…”

Section: Introductionmentioning

confidence: 99%

“…At ecosystem scales, a number of studies have examined how the spatial distribution of R s is affected by vegetation. R s is typically higher closer to tree stems (Epron et al, 2004;Tang and Baldocchi, 2005) and with higher nearby stem density (Schwendenmann and Macinnis-Ng, 2016;Stegen et al, 2017). Photosynthesis is also a driver of the rhizospheric component of soil respiration (Hopkins et al, 2013) and influences seasonal trends in root contribution to total soil respiration (Braendholt et al, 2018;.…”

Section: Introductionmentioning

confidence: 99%

Localized basal area affects soil respiration temperature sensitivity in a coastal deciduous forest

et al. 2020

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Abstract. Soil respiration (Rs), the flow of CO2 from the soil surface to the atmosphere, is one of the largest carbon fluxes in the terrestrial biosphere. The spatial variability of Rs is both large and poorly understood, limiting our ability to robustly scale it in space. One factor in Rs spatial variability is the autotrophic contribution from plant roots, but it is uncertain how the presence of plants affects the magnitude and temperature sensitivity of Rs. This study used 1 year of Rs measurements to examine the effect of localized basal area on Rs in the growing and dormant seasons, as well as during moisture-limited times, in a temperate, coastal, deciduous forest in eastern Maryland, USA. In a linear mixed-effects model, tree basal area within a 5 m radius (BA5) exerted a significant positive effect on the temperature sensitivity of soil respiration. Soil moisture was the dominant control on Rs during the dry portions of the year, while soil moisture, temperature, and BA5 all exerted significant effects on Rs in wetter periods. Our results suggest that autotrophic respiration is more sensitive to temperature than heterotrophic respiration at these sites, although we did not measure these source fluxes directly, and that soil respiration is highly moisture sensitive, even in a record-rainfall year. The Rs flux magnitudes (0.46–15.0 µmol m−2 s−1) and variability (coefficient of variability 10 %–23 % across plots) observed in this study were comparable to values observed in similar forests. Six Rs observations would be required in order to estimate the mean across all study sites to within 50 %, and 518 would be required in order to estimate it to within 5 %, with 95 % confidence. A better understanding of the spatial interactions between plants and microbes, as well as the strength and speed of above- and belowground coupling, is necessary to link these processes with large-scale soil-to-atmosphere C fluxes.

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“…These two studies used a similar method (infrared gas analyser attached to soil respiration chamber) to measure soil CO2 efflux in their sites and therefore, with comparable results. The spatial variation in RTOT values may be explained by differences in the mean annual temperatures registered in the Finnish and Irish sites respectively (4.0 vs. 10.2ºC), differences in previous land use and management (agricultural fields vs. heather-dominated blanket peat) and root biomass (Schwendenmann and Macinnis-Ng 2016).…”

Section: Total Soil Respirationmentioning

confidence: 99%

Soil respiration partitioning in afforested temperate peatlands

2018

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Understanding and quantifying soil respiration and its component fluxes are necessary to model global carbon cycling in a changing climate as small changes in soil CO2 fluxes could have important implications for future climatic conditions. A soil respiration partitioning study was conducted in eight afforested peatland sites in southwest Ireland. Using trenched points, annual soil CO2 emissions, and the contributions of autotrophic and heterotrophic respiration as components of total soil respiration, were estimated. Nonlinear regression models were evaluated to determine the best predictive soil respiration model for each component flux, using soil temperature and water table level as explanatory variables. Temporal variation in soil CO2 efflux was driven by soil temperature at 10 cm depth, with all treatment points also affected by water table level fluctuations. The effect of water table level on soil respiration was best accounted for by incorporating a water level Gaussian function into the soil-temperature-soil-respiration model. Mean autotrophic respiration was 44% of mean total soil respiration, varying between 1100-2049 g CO2 m -2 year -1 . Heterotrophic respiration was divided between peat respiration and litter respiration, which accounted for 35 and 21% of total soil respiration, respectively. While peat respiration varied between 774-1492 g CO2 m -2 year -1 , litter respiration varied between 514-1013 g CO2 m -2 year -1 . Although the extrapolation of these results to other sites should be done with caution, the empirical models developed for the entire dataset in this study are a useful tool to predict and simulate CO2 emissions in afforested peatland in temperate climates.

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Soil CO<sub>2</sub> efflux in an old-growth southern conifer forest (<i>Agathis australis</i>) – magnitude, components and controls

Cited by 14 publications

References 111 publications

Linking Soil CO2 Efflux to Individual Trees: Size-Dependent Variation and the Importance of the Birch Effect

Linking Soil CO2 Efflux to Individual Trees: Size-Dependent Variation and the Importance of the Birch Effect

Localized basal area affects soil respiration temperature sensitivity in a coastal deciduous forest

Soil respiration partitioning in afforested temperate peatlands

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