A multiisotope C and N modeling analysis of soil organic matter turnover and transport as a function of soil depth in a California annual grassland soil chronosequence

Baisden, W. T.; Amundson, Ronald; Brenner, Dana L.; Cook, A. C.; Kendall, Carol; Harden, J. W.

doi:10.1029/2001gb001823

Cited by 153 publications

(209 citation statements)

References 69 publications

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“…Values of δ 15 N increased with depth, as has been observed before (e.g. Mariotti et al, 1980;Baisden et al, 2002b), and were on average 1.7‰ (s.d. ±0.8‰) larger in the mOM fraction.…”

Section: Resultssupporting

confidence: 59%

Relative stability of soil carbon revealed by shifts in δ<sup>15</sup>N and C:N ratio

Conen

Zimmermann

Leifeld³

et al. 2008

Biogeosciences

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Abstract. Life on earth drives a continuous exchange of carbon between soils and the atmosphere. Some forms of soil carbon, or organic matter, are more stable and have a longer residence time in soil than others. Relative differences in stability have often been derived from shifts in δ 13 C (which is bound to a vegetation change from C3 to C4 type) or through 14 C-dating (which is bound to small sample numbers because of high measurement costs). Here, we propose a new concept based on the increase in δ 15 N and the decrease in C:N ratio with increasing stability. We tested the concept on grasslands at different elevations in the Swiss Alps. Depending on elevation and soil depth, it predicted mineral-associated organic carbon to be 3 to 73 times more stable than particulate organic carbon. Analysis of 14 C-ages generally endorsed these predictions.

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Section: Resultssupporting

confidence: 59%

Relative stability of soil carbon revealed by shifts in δ<sup>15</sup>N and C:N ratio

Conen

Zimmermann

Leifeld³

et al. 2008

Biogeosciences

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“…These results argue that the traditional ecological perspective of POC as fragmented and egested leaf litter (Vannote et al 1980) requires modification to include mineral-core and algal-derived particles as components of the suspended load. Furthermore, our results detail variability in POC fluxes and quality (i.e., carbon content of seston), which control carbon bioavailability (Baisden et al 2002) and should ultimately influence rates of heterotrophic respiration in downstream rivers (Mayorga et al 2005). Future work is needed to advance the understanding of the role of river networks in controlling the transformations of allochthonous and autochthonous POC transported from inland waters to the oceans.…”

Section: Discussionmentioning

confidence: 99%

Temporal dynamics of seston: A recurring nighttime peak and seasonal shifts in composition in a stream ecosystem

et al. 2009

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We measured the baseflow concentration and composition of seston and suspended particulate organic carbon (POC) over a 1-yr period in White Clay Creek, a third-order stream in the southeastern Pennsylvania Piedmont, to assess temporal variability in seston concentration and quality at seasonal and diel timescales. Each month, we sampled stream water under baseflow conditions every 1.5 h over a 24-h period and measured seston and POC concentrations, carbon composition, pigment content, and 13 C isotopic ratios. Seston and POC concentrations exhibited a strong diel pattern; nighttime concentrations exceeded daytime concentrations by 80% and 43%, respectively. Suspended chlorophyll a concentrations did not exhibit a diel pattern. We attribute the diel pattern of seston concentration to bioturbation by the nocturnal stream community, including crayfish, amphibians, eels, and macroinvertebrates. Seasonally, carbon content of seston increased from 9% throughout most of the year to 15% during November, December, and March, while seston d 13 C was depleted in the late fall and enriched in early spring months relative to the rest of the year. Chlorophyll a and pheophytin a concentrations in seston peaked during the early spring. Seasonal patterns in seston and POC composition reflect cycles of autumnal leaf litter inputs and vernal algal production. Bioturbation and shifts in organic carbon inputs mediate changes in POC quality and fluxes, which affect the bioavailability of POC and ultimately influence rates of heterotrophic respiration.

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“…Oelbermann and Voroney (2011) evaluated the ability of the CENTURY model (Parton et al, 1987) to predict SOC stocks in tropical and temperate agroforestry systems, but with a singlelayer modeling approach (0-20 cm). The approach of modeling a single topsoil layer assumes that deep SOC does not play an active role in carbon cycling, while it was shown that deep soil layers contain important amounts of SOC (Jobbagy and Jackson, 2000) and that part of this deep SOC could cycle on decadal timescales due to root inputs or dissolved organic carbon transport (Baisden and Parfitt, 2007;Koarashi et al, 2012). The need to take into account deep soil layers when modeling SOC dynamics is now well recognized in the scientific community (Baisden et al, 2002;Elzein and Balesdent, 1995), and several models have been proposed (Braakhekke et al, 2011;Guenet et al, 2013;Koven et al, 2013;Taghizadeh-Toosi et al, 2014;Ahrens et al, 2015).…”

mentioning

confidence: 99%

High organic inputs explain shallow and deep SOC storage in a long-term agroforestry system – combining experimental and modeling approaches

et al. 2018

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Abstract. Agroforestry is an increasingly popular farming system enabling agricultural diversification and providing several ecosystem services. In agroforestry systems, soil organic carbon (SOC) stocks are generally increased, but it is difficult to disentangle the different factors responsible for this storage. Organic carbon (OC) inputs to the soil may be larger, but SOC decomposition rates may be modified owing to microclimate, physical protection, or priming effect from roots, especially at depth. We used an 18-year-old silvoarable system associating hybrid walnut trees (Juglans regia × nigra) and durum wheat (Triticum turgidum L. subsp. durum) and an adjacent agricultural control plot to quantify all OC inputs to the soil -leaf litter, tree fine root senescence, crop residues, and tree row herbaceous vegetation -and measured SOC stocks down to 2 m of depth at varying distances from the trees. We then proposed a model that simulates SOC dynamics in agroforestry accounting for both the whole soil profile and the lateral spatial heterogeneity. The model was calibrated to the control plot only.Measured OC inputs to soil were increased by about 40 % (+ 1.11 t C ha −1 yr −1 ) down to 2 m of depth in the agroforestry plot compared to the control, resulting in an additional SOC stock of 6.3 t C ha −1 down to 1 m of depth. However, most of the SOC storage occurred in the first 30 cm of soil and in the tree rows. The model was strongly validated, properly describing the measured SOC stocks and distribution with depth in agroforestry tree rows and alleys. It showed that the increased inputs of fresh biomass to soil explained the observed additional SOC storage in the agroforestry plot. Moreover, only a priming effect variant of the model was able to capture the depth distribution of SOC stocks, suggesting the priming effect as a possible mechanism driving deep SOC dynamics. This result questions the potential of soils to store large amounts of carbon, especially at depth. Deep-rooted trees modify OC inputs to soil, a process that deserves further study given its potential effects on SOC dynamics.

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A multiisotope C and N modeling analysis of soil organic matter turnover and transport as a function of soil depth in a California annual grassland soil chronosequence

Cited by 153 publications

References 69 publications

Relative stability of soil carbon revealed by shifts in δ<sup>15</sup>N and C:N ratio

Relative stability of soil carbon revealed by shifts in δ<sup>15</sup>N and C:N ratio

Temporal dynamics of seston: A recurring nighttime peak and seasonal shifts in composition in a stream ecosystem

High organic inputs explain shallow and deep SOC storage in a long-term agroforestry system – combining experimental and modeling approaches

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A multiisotope C and N modeling analysis of soil organic matter turnover and transport as a function of soil depth in a California annual grassland soil chronosequence

Cited by 153 publications

References 69 publications

Relative stability of soil carbon revealed by shifts in δ&lt;sup&gt;15&lt;/sup&gt;N and C:N ratio

Relative stability of soil carbon revealed by shifts in δ&lt;sup&gt;15&lt;/sup&gt;N and C:N ratio

Temporal dynamics of seston: A recurring nighttime peak and seasonal shifts in composition in a stream ecosystem

High organic inputs explain shallow and deep SOC storage in a long-term agroforestry system – combining experimental and modeling approaches

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Relative stability of soil carbon revealed by shifts in δ<sup>15</sup>N and C:N ratio

Relative stability of soil carbon revealed by shifts in δ<sup>15</sup>N and C:N ratio