scholarly journals Microbial activity and root carbon inputs are more important than soil carbon diffusion in simulating soil carbon profiles

2021 ◽  
Author(s):  
Ying‐Ping Wang ◽  
Haicheng Zhang ◽  
Philippe Ciais ◽  
Daniel Goll ◽  
Yuanyuan Huang ◽  
...  
Keyword(s):  
Soil Carbon ◽  
Microbial Activity ◽  
Carbon Diffusion ◽  
Root Carbon

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

2014 ◽  
Vol 11 (2) ◽  
pp. 2227-2266 ◽  
Author(s):  
Y. He ◽  
Q. Zhuang ◽  
J. W. Harden ◽  
A. D. McGuire ◽  
Z. Fan ◽  
...  
Keyword(s):  
Soil Carbon ◽  
Microbial Activity ◽  
Size Variation ◽  
Pool Size ◽  
Soil Horizon ◽  
Biogeochemical Processes ◽  
Soil Horizons ◽  
Model Framework ◽  
Carbon Decomposition ◽  
Decomposition Models

Abstract. The large magnitudes of soil carbon stocks provide potentially large feedbacks to climate changes, highlighting the 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 mechanistically based soil decomposition model framework for boreal forest ecosystems. A global 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 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 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.

scholarly journals CO2-C losses and carbon quality of selected Maritime Antarctic soils

2012 ◽  
Vol 25 (1) ◽  
pp. 11-18 ◽  
Author(s):  
Juliana Vanir De Souza Carvalho ◽  
Eduardo De Sá Mendonça ◽  
Newton La Scala ◽  
César Reis ◽  
Efrain Lázaro Reis ◽  
...  
Keyword(s):  
Organic Matter ◽  
Soil Organic Matter ◽  
Soil Temperature ◽  
Soil Carbon ◽  
Humic Substances ◽  
Microbial Activity ◽  
Chemical Characteristics ◽  
Maritime Antarctic ◽  
Antarctic Soils ◽  
Humification Degree

AbstractPolar Regions are the most important soil carbon reservoirs on Earth. Monitoring soil carbon storage in a changing global climate context may indicate possible effects of climate change on terrestrial environments. In this regard, we need to understand the dynamics of soil organic matter in relation to its chemical characteristics. We evaluated the influence of chemical characteristics of humic substances on the process of soil organic matter mineralization in selected Maritime Antarctic soils. A laboratory assay was carried out with soils from five locations from King George Island. We determined the contents of total organic carbon, oxidizable carbon fractions of soil organic matter, and humic substances. Two in situ field experiments were carried out during two summers, in order to evaluate the CO2-C emissions in relation to soil temperature variations. The overall low amounts of soil organic matter in Maritime Antarctic soils have a low humification degree and reduced microbial activity. CO2-C emissions showed significant exponential relationship with temperature, suggesting a sharp increase in CO2-C emissions with a warming scenario, and Q10 values (the percentage increase in emission for a 10°C increase in soil temperature) were higher than values reported from elsewhere. The sensitivity of the CO2-C emission in relation to temperature was significantly correlated with the humification degree of soil organic matter and microbial activity for Antarctic soils.

scholarly journals A deeper look at the relationship between root carbon pools and the vertical distribution of the soil carbon pool

2017 ◽  
Author(s):  
Ranae Dietzel ◽  
Matt Liebman ◽  
Sotirios Archontoulis
Keyword(s):  
Soil Carbon ◽  
Plant Root ◽  
Substantial Contribution ◽  
Root Turnover ◽  
Soil Organic C ◽  
Organic C ◽  
Native Prairie ◽  
Perennial Plant ◽  
Root Carbon ◽  
The Relationship

Abstract. Plant root material makes a substantial contribution to the soil organic carbon (C) pool, but this contribution is disproportionate below 20 cm, where 30 % of root mass and 50 % of soil organic C is found. Root carbon inputs changed drastically when native perennial plant systems were shifted to cultivated annual plant systems. We used the reconstruction of a native prairie and a continuous maize field to examine both the relationship between root carbon and soil carbon and the fundamental rooting system differences between the vegetation under which the soils developed versus the vegetation under which the soils continue to change. In all treatments we found that root C : N ratios increased with depth, which may help explain why an unexpectedly large proportion of soil organic C is found below 20 cm. Measured root C : N ratios and turnover times along with modeled root turnover dynamics showed that in moving from prairie to maize, a large, structural-tissue dominated root C pool with slow turnover, concentrated at shallow depths was replaced by a small, non-structural-tissue dominated root C pool with fast turnover evenly distributed in the soil profile. These differences in rooting systems suggest that while prairie roots contribute more C to the soil than maize at shallow depths, maize may contribute more C to the soil than prairies at deeper depths.

scholarly journals Seasonal/Interannual Variations of Carbon Sequestration and Carbon Emission in a Warm-Season Perennial Grassland

2014 ◽  
Vol 2014 ◽  
pp. 1-13
Author(s):  
Deepa Dhital ◽  
Tomoharu Inoue ◽  
Hiroshi Koizumi
Keyword(s):  
Carbon Sequestration ◽  
Soil Carbon ◽  
Carbon Emission ◽  
Warm Season ◽  
Growing Season ◽  
Interannual Variations ◽  
Root Carbon ◽  
Ground Biomass ◽  
Below Ground ◽  
Perennial Grassland

Carbon sequestration and carbon emission are processes of ecosystem carbon cycling that can be affected while land area converted to grassland resulting in increased soil carbon storage and below-ground respiration. Discerning the importance of carbon cycle in grassland, we aimed to estimate carbon sequestration in photosynthesis and carbon emission in respiration from soil, root, and microbes, for four consecutive years (2007–2010) in a warm-season perennial grassland, Japan. Soil carbon emission increased with increasing growing season temperature which ranged from 438 to 1642 mg CO2 m−2 h−1. Four years’ average soil carbon emission for growing season, nongrowing season, and annual emission was 1123, 364, and 1488 g C m−2, respectively. Nongrowing and snow covered season soil carbon emission contributed 23–25% and 14–17% to the annual emission. Above-ground biomass varied seasonally and variation in green biomass affected soil carbon emission with increasing temperature and precipitation. Temperature effect on root carbon emission contributed about 1/4th of the total soil carbon emission. Variation in soil and root carbon emission is affected by below-ground biomass. Long-term estimation concluded that seasonal and interannual variations in carbon sequestration and emission are very common in grassland ecosystem.

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.

scholarly journals SPATIAL AND VERTICAL DISTRIBUTION OF LITTER AND BELOWGROUND CARBON IN A BRAZILIAN CERRADO VEGETATION

CERNE ◽  
2017 ◽  
Vol 23 (1) ◽  
pp. 43-52 ◽  
Author(s):  
Vinícius Augusto Morais ◽  
Carla Alessandra Santos ◽  
José Márcio Mello ◽  
Hassan Camil Dadid ◽  
Emanuel José Gomes Araújo ◽  
...  
Keyword(s):  
Vertical Distribution ◽  
Soil Carbon ◽  
Carbon Stock ◽  
Soil Depth ◽  
Soil Layer ◽  
Total Carbon ◽  
Coarse Roots ◽  
Soil Layers ◽  
Root Carbon ◽  
Spatial And Vertical Distribution

ABSTRACT Forest ecosystems contribute significantly to store greenhouse gases. This paper aimed to investigate the spatial and vertical distribution of litter, roots, and soil carbon. We obtained biomass and carbon of compartments (litter, roots, and soil) in a vegetation from Cerrado biome, state of Minas Gerais, Brazil. The materials were collected in 7 0.5 m² sub-plots randomly allocated in the vegetation. Root and soil samples were taken from five soil layers across the 0-100 cm depth. Roots were classified into three diameter classes: fine (<5 mm), medium (5-10 mm), and coarse (>10 mm) roots. The carbon stock was mapped through geostatistical analysis. The results indicated averages of soil carbon stock of 208.5 Mg.ha-1 (94.6% of the total carbon), root carbon of 6.8 Mg.ha-1 (3.1%), and litter of 5 Mg.ha-1 (2.3%). The root carbon was majority stored in coarse roots (83%), followed by fine (10%), and medium roots (7%). The largest portion of fine roots concentrated in the 0-10 cm soil depth, whereas medium and coarse roots were majority in the 10-20 cm depth. The largest portion of soil (53%) and root (85%) carbon were stored in superficial soil layers (above 40 cm). As conclusion, the carbon spatial distribution follows a reasonable trend among the compartments. There is a vertical relation of which the deeper the soil layer, the lower the soil and root carbon stock. Excepting the shallowest layer, coarse roots held the largest portion of carbon across the evaluated soil layers.

Root carbon inputs under moderately diverse sward and conventional ryegrass-clover pasture: implications for soil carbon sequestration

2015 ◽  
Vol 392 (1-2) ◽  
pp. 289-299 ◽  
Author(s):  
Samuel Rae McNally ◽  
Daniel C. Laughlin ◽  
Susanna Rutledge ◽  
Mike B. Dodd ◽  
Johan Six ◽  
...  
Keyword(s):  
Carbon Sequestration ◽  
Soil Carbon ◽  
Soil Carbon Sequestration ◽  
Root Carbon ◽  
Clover Pasture
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