A carbon-budget approach shows that reduced decomposition causes the nitrogen-induced increase in soil carbon in a boreal forest

2021 ◽  
Vol 502 ◽  
pp. 119750
Author(s):  
John D. Marshall ◽  
Matthias Peichl ◽  
Lasse Tarvainen ◽  
Hyungwoo Lim ◽  
Tomas Lundmark ◽  
...  
Keyword(s):  
Boreal Forest ◽  
Soil Carbon ◽  
Carbon Budget ◽  
Reduced Decomposition

Agriculture in the Boreal Forest: Understanding the Impact of Land Use Change on Soil Carbon for Developing Sustainable Community Food Systems 

2021 ◽  
Author(s):  
David Bysouth ◽  
Merritt Turetsky ◽  
Andrew Spring
Keyword(s):  
Climate Change ◽  
Land Use ◽  
Land Use Change ◽  
Boreal Forest ◽  
Soil Carbon ◽  
Food Systems ◽  
Agricultural Land ◽  
Carbon Stocks ◽  
Soil Carbon Stocks ◽  
Carbon Losses

<p>Climate change is causing rapid warming at northern high latitudes and disproportionately affecting ecosystem services that northern communities rely upon. In Canada’s Northwest Territories (NWT), climate change is impacting the access and availability of traditional foods that are critical for community health and well-being. With climate change potentially expanding the envelope of suitable agricultural land northward, many communities in the NWT are evaluating including agriculture in their food systems. However, the conversion of boreal forest to agriculture may degrade the carbon rich soils that characterize the region, resulting in large carbon losses to the atmosphere and the depletion of existing ecosystem services associated with the accumulation of soil organic matter. Here, we first summarize the results of 35 publications that address land use change from boreal forest to agriculture, with the goal of understanding the magnitude and drivers of carbon stock changes with time-since-land use change. Results from the literature synthesis show that conversion of boreal forest to agriculture can result in up to ~57% of existing soil carbon stocks being lost 30 years after land use change occurs. In addition, a three-way interaction with soil carbon, pH and time-since-land use change is observed where soils become more basic with increasing time-since-land use change, coinciding with declines in soil carbon stocks. This relationship is important when looking at the types of crops communities are interested in growing and the type of agriculture associated with cultivating these crops. Partnered communities have identified crops such as berry bushes, root vegetables, potatoes and corn as crops they are interested in growing. As berry bushes grow in acidic conditions and the other mentioned crops grow in more neutral conditions, site selection and management practices associated with growing these crops in appropriate pH environments will be important for managing soil carbon in new agricultural systems in the NWT. Secondly, we also present community scale soil data assessing variation in soil carbon stocks in relation to potential soil fertility metrics targeted to community identified crops of interest for two communities in the NWT.  We collected 192 soil cores from two communities to determine carbon stocks along gradients of potential agriculture suitability. Our field soil carbon measurements in collaboration with the partnered NWT communities show that land use conversions associated with agricultural development could translate to carbon losses ranging from 2.7-11.4 kg C/m<sup>2</sup> depending on the type of soil, agricultural suitability class, and type of land use change associated with cultivation. These results highlight the importance of managing soil carbon in northern agricultural systems and can be used to emphasize the need for new community scale data relating to agricultural land use change in boreal soils. Through the collection of this data, we hope to provide northern communities with a more robust, community scale product that will allow them to make informed land use decisions relating to the cultivation of crops and the minimization of soil carbon losses while maintaining the culturally important traditional food system.</p>

Carbon input threshold for soil carbon budget optimization in eroding vineyards

Geoderma ◽  
2016 ◽  
Vol 271 ◽  
pp. 144-149 ◽  
Author(s):  
Andrés García-Díaz ◽  
Ramón Bienes Allas ◽  
Luciano Gristina ◽  
Artemio Cerdà ◽  
Paulo Pereira ◽  
...  
Keyword(s):  
Soil Carbon ◽  
Carbon Budget ◽  
Budget Optimization

scholarly journals The implications of microbial and substrate limitation for the fates of carbon in different organic soil horizon types of boreal forest ecosystems: a mechanistically based model analysis

2014 ◽  
Vol 11 (16) ◽  
pp. 4477-4491 ◽  
Author(s):  
Y. He ◽  
Q. Zhuang ◽  
J. W. Harden ◽  
A. D. McGuire ◽  
Z. Fan ◽  
...  
Keyword(s):  
Boreal Forest ◽  
Soil Carbon ◽  
Microbial Activity ◽  
Forest Ecosystems ◽  
Size Variation ◽  
Pool Size ◽  
Biogeochemical Processes ◽  
Soil Horizons ◽  
Carbon Decomposition ◽  
Decomposition Models

Abstract. The large amount of soil carbon in boreal forest ecosystems has the potential to influence the climate system if released in large quantities in response to warming. Thus, there is a need to better understand and represent the environmental sensitivity of soil carbon decomposition. Most soil carbon decomposition models rely on empirical relationships omitting key biogeochemical mechanisms and their response to climate change is highly uncertain. In this study, we developed a multi-layer microbial explicit soil decomposition model framework for boreal forest ecosystems. A thorough sensitivity analysis was conducted to identify dominating biogeochemical processes and to highlight structural limitations. Our results indicate that substrate availability (limited by soil water diffusion and substrate quality) is likely to be a major constraint on soil decomposition in the fibrous horizon (40–60% of soil organic carbon (SOC) pool size variation), while energy limited microbial activity in the amorphous horizon exerts a predominant control on soil decomposition (>70% of SOC pool size variation). Elevated temperature alleviated the energy constraint of microbial activity most notably in amorphous soils, whereas moisture only exhibited a marginal effect on dissolved substrate supply and microbial activity. Our study highlights the different decomposition properties and underlying mechanisms of soil dynamics between fibrous and amorphous soil horizons. Soil decomposition models should consider explicitly representing different boreal soil horizons and soil–microbial interactions to better characterize biogeochemical processes in boreal forest ecosystems. A more comprehensive representation of critical biogeochemical mechanisms of soil moisture effects may be required to improve the performance of the soil model we analyzed in this study.

Carbon and nitrogen in the silt-size fraction and its HCl-hydrolysis residues from coarse-textured Canadian boreal forest soils

2014 ◽  
Vol 94 (2) ◽  
pp. 157-168 ◽  
Author(s):  
Caroline M. Preston ◽  
Charlotte E. Norris ◽  
Guy M. Bernard ◽  
David W. Beilman ◽  
Sylvie A. Quideau ◽  
...  
Keyword(s):  
Boreal Forest ◽  
Soil Carbon ◽  
Forest Soils ◽  
Mineral Soil ◽  
Size Fraction ◽  
Soil C ◽  
Carbon And Nitrogen ◽  
Total Soil ◽  
C Stocks ◽  
Canadian Boreal Forest

Preston, C. M., Norris, C. E., Bernard, G. M., Beilman, D. W., Quideau, S. A. and Wasylishen, R. E. 2014. Carbon and nitrogen in the silt-size fraction and its HCl-hydrolysis residues from coarse-textured Canadian boreal forest soils. Can. J. Soil Sci. 94: 157–168. Improving the capacity to predict changes in soil carbon (C) stocks in the Canadian boreal forest requires better information on the characteristics and age of soil carbon, especially more slowly cycling C in mineral soil. We characterized C in the silt-size fraction, as representative of C stabilized by mineral association, previously isolated in a study of soil profiles of four sandy boreal jack pine sites. Silt-size fraction accounted for 13–31% of the total soil C and 12–51% of the total soil N content. Solid-state 13C nuclear magnetic resonance spectroscopy showed that silt C was mostly dominated by alkyl and O,N-alkyl C, with low proportions of aryl C in most samples. Thus, despite the importance of fire in this region, there was little evidence of storage of pyrogenic C. We used HCl hydrolysis to isolate the oldest C within the silt-size fraction. Consistent with previous studies, this procedure removed 21–74% of C and 74–93% of N, leaving residues composed mainly of alkyl and aryl C. However, it failed to isolate consistently old C; 11 out of 16 samples had recent 14C ages (fraction of modern 14C > 1), although C-horizon samples were older, with Δ14C from –17 to –476‰. Our results indicate relatively young ages for C associated with the silt-size fractions in these sites, for which mineral soil C storage may be primarily limited by good drainage and coarse soil texture, exacerbated by losses due to periodic wildfire.

scholarly journals A revised northern soil Hg pool, based on western Siberia permafrost peat Hg and carbon observations

2020 ◽  
Author(s):  
Artem G. Lim ◽  
Martin Jiskra ◽  
Jeroen E. Sonke ◽  
Sergey V. Loiko ◽  
Natalia Kosykh ◽  
...  
Keyword(s):  
Soil Carbon ◽  
Carbon Budget ◽  
Western Siberia ◽  
Mineral Soil ◽  
Peat Soils ◽  
Run Off ◽  
Permafrost Soils ◽  
Siberian Permafrost ◽  
Soil Hg ◽  
Carbon Inventory

Abstract. Natural and anthropogenic mercury (Hg) emissions are sequestered in terrestrial soils over short, annual, to long, millennial time scales, before Hg mobilization and run-off impacts wetland and coastal Ocean ecosystems. Recent studies have used Hg to carbon (C) ratios, RHgC, measured in Alaskan permafrost mineral and peat soils, together with a northern soil carbon inventory, to estimate that these soils contain large amounts, 184 to 755 Gg of Hg in the upper 1 m. However, measurements of RHgC on Siberian permafrost peatlands are largely missing, leaving the size of estimated northern soil Hg budget, and its fate under arctic warming scenarios uncertain. Here we present Hg and carbon data for 6 peat cores, down to mineral horizons at 1.5–4 m depth, across a 1700 km latitudinal (56 to 67° N) permafrost gradient in the Western Siberian lowlands (WSL). Hg concentrations increase from south to north in all soil horizons, reflecting enhanced net accumulation of atmospheric gaseous Hg by the vegetation Hg pump. The RHgC in WSL peat horizons decreases with depth from 0.38 Gg Pg−1 in the active layer to 0.23 Gg Pg−1 in continuously frozen peat of the WSL. We estimate the Hg pool (0 1 m) in the permafrost-affected part of WSL peatlands to be 9.3 ± 2.7 Gg. We review and estimate pan-arctic organic and mineral soil RHgC to be 0.19 and 0.77 Gg Pg−1, and use a soil carbon budget to revise the northern soil Hg pool to be 67 Gg (37–88 Gg, interquartile range (IQR)) in the upper 30 cm, 225 Gg (102–320 Gg) in the upper 1 m, and 557 Gg (371–699 Gg) in the upper 3 m. Using the same RHgC approach, we revise the global upper 30 cm soil Hg pool to contain 1078 Gg of Hg (842–1254 Gg, IQR), of which 6 % (67 Gg) resides in northern permafrost soils. Additional soil and river studies must be performed in Eastern and Northern Siberia to lower the uncertainty on these estimates, and assess the timing of Hg release to atmosphere and rivers.

Assessing the impact of cover crop as a GHG mitigation solution at intra-field scale using the AgriCarbon-EO tool

2021 ◽  
Author(s):  
Taeken Wijmer ◽  
Ahmad Al Bitar ◽  
Remy Fieuzal ◽  
Ludovic Arnaud ◽  
Gaetan Pique ◽  
...  
Keyword(s):  
High Resolution ◽  
Soil Carbon ◽  
Cover Crops ◽  
Cover Crop ◽  
Carbon Budget ◽  
Carbon Stocks ◽  
Optical Data ◽  
Agricultural Practice ◽  
Soil Carbon Stocks ◽  
Sentinel 2

<p>Increasing soil carbon stocks has been identified as a major climate change mitigation solution. As a consequence, an objective of 4/1000 yearly increment in soil carbon stocks has been proposed at the COP21.  Sustainable agriculture provides several solutions to meet this objective and among those solutions, the implementation of cover crops has been identified as most efficient. Currently, a comprehensive modeling tool that takes into account the major bio-geophysical processes with associated uncertainties, while assimilating frequent high-resolution observations at large scale could allow accounting for the effect of cover crops on the carbon budget in a realistic way. In this study, we quantify the components of the carbon budget at high resolution and we analyse the effect of cover crops. Computations are based on the newly developed AgriCarbon-EO tool which assimilates full resolution (10-20m) Sentinel-2 optical data into a radiative transfer model (PROSAIL), and a crop model (SAFYE-CO2). The assimilation scheme is based on a Bayesian approach which provides the retrieved biogeophysical variables with their associated uncertainties. Uncertainties are essential when determining the carbon stocks. For instance, the future European Common Agricultural Practice (CAP) may take into consideration the uncertainty of the determination of the soil carbon stocks changes in the evaluation of the subsidies. The main inputs of the computations are weather data, soil texture maps, crop maps and surface reflectances. The Sentinel-2 Leaf Area Index (LAI) are obtained from those Sentinel-2 surface reflectance by inverting the PROSAIL model. These are then assimilated into the SAFY_CO2 model to determine the carbon budget components. To validate our approach, we implemented the AgriCarbon-EO tool over a set of plots in south-western France over which we dispose of biomass measurements for cover crops in wheat/cover crop/maize rotations for 2017-2018 and 2019-2020 agricultural seasons. Also, the CO2 fluxes are validated against eddy covariance flux measurements in the same context. Our study shows that the cover crops allow on average 250gC/m² of organic carbon with a high spatial heterogeneity. This has important implications regarding the dynamic of carbon storage in agronomic soils and demonstrates the importance of high-resolution agronomic modeling.</p>

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