scholarly journals Investigating the sensitivity of soil respiration to recent snow cover changes in Alaska using a satellite-based permafrost carbon model

2020 ◽  
Author(s):  
Yonghong Yi ◽  
John S. Kimball ◽  
Jennifer D. Watts ◽  
Susan M. Natali ◽  
Donatella Zona ◽  
...  
Keyword(s):  
Soil Respiration ◽  
Soil Temperature ◽  
Soil Carbon ◽  
Snow Cover ◽  
Carbon Fluxes ◽  
Cold Season ◽  
Heterotrophic Respiration ◽  
Surface Model ◽  
Total Soil ◽  
Soil Heterotrophic Respiration

Abstract. The contribution of soil heterotrophic respiration to the boreal-Arctic carbon (CO2) cycle and its potential feedback to climate change remain poorly quantified. We developed a remote sensing driven permafrost carbon model at intermediate scale (~ 1 km) to investigate how environmental factors affect the magnitude and seasonality of soil heterotrophic respiration in Alaska. The permafrost carbon model simulates snow and soil thermal dynamics, and accounts for vertical soil carbon transport and decomposition at depths up to 3 m below surface. Model outputs include soil temperature profiles and carbon fluxes at 1-km resolution spanning the recent satellite era (2001–2017) across Alaska. Comparisons with eddy covariance tower measurements show that the model captures the seasonality of carbon fluxes, with favorable accuracy in predicting net ecosystem CO2 exchange (NEE) in both tundra (R > 0.8, RMSE = 0.34 g C m−2 d−1) and boreal forest (R > 0.73, RMSE = 0.51 g C m−2 d−1). Benchmark assessments using two regional in-situ datasets indicate that the model captures the complex influence of snow insulation on soil temperature, and the temperature sensitivity of cold-season soil respiration. Across Alaska, we find that seasonal snow cover imposes strong controls on the contribution from different soil depths to total soil carbon emissions. Earlier snow melt in spring promotes deeper soil warming and enhances the contribution of deeper soils to total soil respiration during the later growing season, thereby reducing net ecosystem carbon uptake. Early cold-season soil respiration is closely linked to the number of snow-free days after land surface freezes (R = −0.48, p 

scholarly journals Investigating the sensitivity of soil heterotrophic respiration to recent snow cover changes in Alaska using a satellite-based permafrost carbon model

2020 ◽  
Vol 17 (22) ◽  
pp. 5861-5882
Author(s):  
Yonghong Yi ◽  
John S. Kimball ◽  
Jennifer D. Watts ◽  
Susan M. Natali ◽  
Donatella Zona ◽  
...  
Keyword(s):  
Soil Temperature ◽  
Snow Cover ◽  
Land Surface ◽  
Carbon Fluxes ◽  
Cold Season ◽  
Heterotrophic Respiration ◽  
Surface Model ◽  
Thermal Dynamics ◽  
Total Soil ◽  
Soil Heterotrophic Respiration

Abstract. The contribution of soil heterotrophic respiration to the boreal–Arctic carbon (CO2) cycle and its potential feedback to climate change remains poorly quantified. We developed a remote-sensing-driven permafrost carbon model at intermediate scale (∼1 km) to investigate how environmental factors affect the magnitude and seasonality of soil heterotrophic respiration in Alaska. The permafrost carbon model simulates snow and soil thermal dynamics and accounts for vertical soil carbon transport and decomposition at depths up to 3 m below the surface. Model outputs include soil temperature profiles and carbon fluxes at 1 km resolution spanning the recent satellite era (2001–2017) across Alaska. Comparisons with eddy covariance tower measurements show that the model captures the seasonality of carbon fluxes, with favorable accuracy in simulating net ecosystem CO2 exchange (NEE) for both tundra (R>0.8, root mean square error (RMSE – 0.34 g C m−2 d−1), and boreal forest (R>0.73; RMSE – 0.51 g C m−2 d−1). Benchmark assessments using two regional in situ data sets indicate that the model captures the complex influence of snow insulation on soil temperature and the temperature sensitivity of cold-season soil heterotrophic respiration. Across Alaska, we find that seasonal snow cover imposes strong controls on the contribution from different soil depths to total soil heterotrophic respiration. Earlier snowmelt in spring promotes deeper soil warming and enhances the contribution of deeper soils to total soil heterotrophic respiration during the later growing season, thereby reducing net ecosystem carbon uptake. Early cold-season soil heterotrophic respiration is closely linked to the number of snow-free days after the land surface freezes (R=-0.48, p<0.1), i.e., the delay in snow onset relative to surface freeze onset. Recent trends toward earlier autumn snow onset in northern Alaska promote a longer zero-curtain period and enhanced cold-season respiration. In contrast, southwestern Alaska shows a strong reduction in the number of snow-free days after land surface freeze onset, leading to earlier soil freezing and a large reduction in cold-season soil heterotrophic respiration. Our results also show nonnegligible influences of subgrid variability in surface conditions on the model-simulated CO2 seasonal cycle, especially during the early cold season at 10 km scale. Our results demonstrate the critical role of snow cover affecting the seasonality of soil temperature and respiration and highlight the challenges of incorporating these complex processes into future projections of the boreal–Arctic carbon cycle.

scholarly journals Dynamics of the soil respiration response to soil reclamation in a coastal wetland

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Xiliang Song ◽  
Yihao Zhu ◽  
Weifeng Chen
Keyword(s):  
Soil Respiration ◽  
Soil Temperature ◽  
Soil Carbon ◽  
Water Content ◽  
Coastal Wetlands ◽  
Positive Relationship ◽  
Soil Reclamation ◽  
Diurnal Changes ◽  
Seasonal Scale ◽  
Study Sites

AbstractThe soil carbon (C) pools in coastal wetlands are known as “blue C” and have been damaged extensively owing to climate change and land reclamation. Because soil respiration (RS) is the primary mechanism through which soil carbon is released into the atmosphere at a global scale, investigating the dynamic characteristics of the soil respiration rate in reclaimed coastal wetlands is necessary to understand its important role in maintaining the global C cycle. In the present study, seasonal and diurnal changes in soil respiration were monitored in one bare wetland (CK) and two reclaimed wetlands (CT, a cotton monoculture pattern, and WM, a wheat–maize continuous cropping pattern) in the Yellow River Delta. At the diurnal scale, the RS at the three study sites displayed single-peak curves, with the lowest values occurring at midnight (00:00 a.m.) and the highest values occurring at midday (12:00 a.m.). At the seasonal scale, the mean diurnal RS of the CK, CT and WM in April was 0.24, 0.26 and 0.79 μmol CO2 m−2 s−1, and it increased to a peak in August for these areas. Bare wetland conversion to croplands significantly elevated the soil organic carbon (SOC) pool. The magnitude of the RS was significantly different at the three sites, and the yearly total amounts of CO2 efflux were 375, 513 and 944 g CO2·m−2 for the CK, CT and WM, respectively. At the three study sites, the surface soil temperature had a significant and positive relationship to the RS at both the diurnal and seasonal scales, and it accounted for 20–52% of the seasonal variation in the daytime RS. The soil water content showed a significant but negative relationship to the RS on diurnal scale only at the CK site, while it significantly increased with the RS on seasonal scale at all study sites. Although the RS showed a noticeable relationship to the combination of soil temperature and water content, the synergic effects of these two environment factors were not much higher than the individual effects. In addition, the correlation analysis showed that the RS was also influenced by the soil physico-chemical properties and that the soil total nitrogen had a closer positive relationship to the RS than the other nutrients, indicating that the soil nitrogen content plays a more important role in promoting carbon loss.

scholarly journals Improvement of Soil Respiration Parameterization in a Dynamic Global Vegetation Model and Its Impact on the Simulation of Terrestrial Carbon Fluxes

2018 ◽  
Vol 32 (1) ◽  
pp. 127-143 ◽  
Author(s):  
Dongmin Kim ◽  
Myong-In Lee ◽  
Eunkyo Seo
Keyword(s):  
Spatial Distribution ◽  
Soil Respiration ◽  
Soil Temperature ◽  
Vegetation Type ◽  
Carbon Fluxes ◽  
Decomposition Process ◽  
Spatial And Temporal Variation ◽  
In Situ Observation ◽  
Terrestrial Carbon ◽  
Soil Temperature And Moisture

Abstract The Q10 value represents the soil respiration sensitivity to temperature often used for the parameterization of the soil decomposition process has been assumed to be a constant in conventional numerical models, whereas it exhibits significant spatial and temporal variation in the observations. This study develops a new parameterization method for determining Q10 by considering the soil respiration dependence on soil temperature and moisture obtained by multiple regression for each vegetation type. This study further investigates the impacts of the new parameterization on the global terrestrial carbon flux. Our results show that a nonuniform spatial distribution of Q10 tends to better represent the dependence of the soil respiration process on heterogeneous surface vegetation type compared with the control simulation using a uniform Q10. Moreover, it tends to improve the simulation of the relationship between soil respiration and soil temperature and moisture, particularly over cold and dry regions. The modification has an impact on the soil respiration and carbon decomposition process, which changes gross primary production (GPP) through controlling nutrient assimilation from soil to vegetation. It leads to a realistic spatial distribution of GPP, particularly over high latitudes where the original model has a significant underestimation bias. Improvement in the spatial distribution of GPP leads to a substantial reduction of global mean GPP bias compared with the in situ observation-based reference data. The results highlight that the enhanced sensitivity of soil respiration to the subsurface soil temperature and moisture introduced by the nonuniform spatial distribution of Q10 has contributed to improving the simulation of the terrestrial carbon fluxes and the global carbon cycle.

scholarly journals Significance of soil respiration from biological activity in the degradation processes of different types of organic matter

2020 ◽  
Vol 1 (2) ◽  
pp. 171-179
Keyword(s):  
Climate Change ◽  
Organic Matter ◽  
Soil Moisture ◽  
Soil Respiration ◽  
Soil Temperature ◽  
Temperature Sensitivity ◽  
Soil Co2 Efflux ◽  
Co2 Efflux ◽  
Soil Co2 ◽  
Total Soil

Soil respiration is a major component of global carbon cycle. Therefore, it is crucial to understand the environmental controls on soil respiration for evaluating potential response of ecosystems to climate change. In a temperate deciduous forest (located in Northern-Hungary) we added or removed aboveground and belowground litter to determine total soil respiration. We investigated the relationship between total soil CO2 efflux, soil moisture, and soil temperature. Soil CO2 efflux was measured at each plot using soda-lime method. Temperature sensitivity of soil respiration (Q10) was monitored via measuring soil temperature on an hourly basis, while soil moisture was determined monthly. Soil respiration increased in control plots from the second year after implementing the treatment, but results showed fluctuations from one year to another. The effect of doubled litter was less significant than the effect of removal. Removed litter and root inputs caused substantial decrease in soil respiration. We found that temperature was more influential in the control of soil respiration than soil moisture. In plots with no litter Q10 varied in the largest interval. For treatment with doubled litter layer, temperature sensitivity of CO2 efflux did not change considerably. The effect of increasing soil temperature is more conspicuous to soil respiration in litter removal treatments since lack of litter causes greater irradiation. When exclusively leaf litter was considered, the effect of temperature on soil respiration was lower in treatments with added litter than with removed litter. Our results reveal that soil life is impacted by the absence of organic matter, rather than by an excess of organic matter. Results of CO2 emission from soils with different organic matter content can contribute to sustainable land use, considering the changed climatic factors caused by global climate change.

scholarly journals Contribution of root respiration to total soil respiration during non-growing season in mine reclaimed soil with different covering soil thicknesses

2020 ◽  
Author(s):  
Min Chen ◽  
Xiaoyang Chen ◽  
Zhiyong Hu ◽  
Tingyu Fan ◽  
Shiwen Zhang ◽  
...  
Keyword(s):  
Soil Respiration ◽  
Soil Temperature ◽  
Root Respiration ◽  
Growing Season ◽  
Growth Season ◽  
Soil Thickness ◽  
Total Soil ◽  
Reclaimed Soil ◽  
Total Soil Respiration ◽  
Monthly Variations

Abstract An accurate assessment of root respiration in mine reclaimed soil is important for effectively evaluating mining area ecosystem. This study investigated dynamic changes in root respiration and contribution of root respiration to total soil respiration (Rr/Rt ratio) during the non-growth season in mine reclaimed soil with different covering soil thicknesses. According to covering soil thicknesses, the study area was divided into four sites: 10-25 cm (site A), 25-45 cm (site B), 45-55 cm (site C) and 55-65 cm (site D). From November 2017 to April 2018 (except February in 2018), the soil respiration, root respiration, temperature at 5 cm, water content and root biomass were measured. The results showed that soil temperature and root respiration exhibited similar diurnal and monthly variations. The root respiration was strongly influenced by soil temperature during the non-growing season, which showed an exponential and positive relationship with soil temperature (P<0.001). The root respiration varied with the covering soil thickness and was the greatest with the covering soil thickness at 25–45 cm. The Rr/Rt ratio also exhibited monthly variations. During the non-growth season, the mean value of the Rr/Rt ratio were 51.15% in mine reclaimed soil. The study indicated that root respiration was the primary source of soil respiration and important to estimate the potential of emission of soil CO 2 at regional scale in mine reclaimed soil.

scholarly journals Contribution of root respiration to total soil respiration during non-growing season in mine reclaimed soil with different covering soil thicknesses

2020 ◽  
Author(s):  
Min Chen ◽  
Xiaoyang Chen ◽  
Zhiyong Hu ◽  
Tingyu Fan ◽  
Shiwen Zhang ◽  
...  
Keyword(s):  
Soil Respiration ◽  
Soil Temperature ◽  
Root Respiration ◽  
Regional Scale ◽  
Growing Season ◽  
Soil Thickness ◽  
Total Soil ◽  
Reclaimed Soil ◽  
Total Soil Respiration ◽  
Monthly Variations

Abstract An accurate assessment of root respiration in mine reclaimed soil is important for effectively evaluating mining area ecosystem. This study investigated dynamic changes in root respiration and contribution of root respiration to total soil respiration (Rr/Rt ratio) during the non-growing season in mine reclaimed soil with different covering soil thicknesses. According to covering soil thicknesses, the study area was divided into four sites: 10-25 cm (site A), 25-45 cm (site B), 45-55 cm (site C) and 55-65 cm (site D). From November 2017 to April 2018 (except February in 2018), the soil respiration, root respiration, temperature at 5 cm, water content and root biomass were measured. The results showed that soil temperature and root respiration exhibited similar diurnal and monthly variations. The root respiration was strongly influenced by soil temperature during the non-growing season, which showed an exponential and positive relationship with soil temperature (P<0.001). The root respiration varied with the covering soil thickness and was the greatest with the covering soil thickness at 25–45 cm. The Rr/Rt ratio also exhibited monthly variations. During the non-growing season, the mean value of the Rr/Rt ratio was 51.15% in mine reclaimed soil. The study indicated that root respiration was the primary source of soil respiration and important to estimate the potential emission of soil CO2 at regional scale in mine reclaimed soil.

scholarly journals Assessing the simulated soil hydrothermal regime of the active layer from the Noah-MP land surface model (v1.1) in the permafrost regions of the Qinghai–Tibet Plateau

2021 ◽  
Vol 14 (3) ◽  
pp. 1753-1771
Author(s):  
Xiangfei Li ◽  
Tonghua Wu ◽  
Xiaodong Wu ◽  
Jie Chen ◽  
Xiaofan Zhu ◽  
...  
Keyword(s):  
Soil Temperature ◽  
Snow Cover ◽  
Land Surface ◽  
Tibet Plateau ◽  
Cold Bias ◽  
Surface Model ◽  
Model Parameters ◽  
Hydrothermal Regime ◽  
Qinghai Tibet Plateau ◽  
Permafrost Regions

Abstract. Extensive and rigorous model intercomparison is of great importance before model application due to the uncertainties in current land surface models (LSMs). Without considering the uncertainties in forcing data and model parameters, this study designed an ensemble of 55 296 experiments to evaluate the Noah LSM with multi-parameterization (Noah-MP) for snow cover events (SCEs), soil temperature (ST) and soil liquid water (SLW) simulation, and investigated the sensitivity of parameterization schemes at a typical permafrost site on the Qinghai–Tibet Plateau (QTP). The results showed that Noah-MP systematically overestimates snow cover, which could be greatly resolved when adopting the sublimation from wind and a semi-implicit snow/soil temperature time scheme. As a result of the overestimated snow, Noah-MP generally underestimates ST, which is mostly influenced by the snow process. A systematic cold bias and large uncertainties in soil temperature remain after eliminating the effects of snow, particularly in the deep layers and during the cold season. The combination of roughness length for heat and under-canopy (below-canopy) aerodynamic resistance contributes to resolving the cold bias in soil temperature. In addition, Noah-MP generally underestimates top SLW. The runoff and groundwater (RUN) process dominates the SLW simulation in comparison to the very limited impacts of all other physical processes. The analysis of the model structural uncertainties and characteristics of each scheme would be constructive to a better understanding of the land surface processes in the permafrost regions of the QTP as well as to further model improvements towards soil hydrothermal regime modeling using LSMs.

Evaluation of modelled methane emissions over high-latitude wetlands

2020 ◽  
Author(s):  
Yao Gao ◽  
Eleanor Burke ◽  
Sarah Chadburn ◽  
Maarit Raivonen ◽  
Timo Vesala ◽  
...  
Keyword(s):  
Soil Respiration ◽  
Soil Carbon ◽  
Water Table ◽  
High Latitude ◽  
Land Surface ◽  
Water Table Depth ◽  
Surface Model ◽  
Emission Model ◽  
Earth System ◽  
Positive Feedbacks

&lt;p&gt;Atmospheric emissions and concentrations of CH&lt;sub&gt;4&lt;/sub&gt; are continuing to increase, making CH&lt;sub&gt;4&lt;/sub&gt; the second most important human-influenced greenhouse gas in terms of climate forcing, after CO&lt;sub&gt;2&lt;/sub&gt;. Previous studies indicated that wetland CH&lt;sub&gt;4&lt;/sub&gt; emission is not only the single largest but also the most uncertain natural source in the global CH&lt;sub&gt;4&lt;/sub&gt; budget. Furthermore, the strong sensitivity of wetland CH&lt;sub&gt;4&lt;/sub&gt; emissions to environmental conditions has raised concerns on potential positive feedbacks to climate change. Therefore, evaluation of the process-based land surface models of earth system models (ESMs) in simulating CH&lt;sub&gt;4&lt;/sub&gt; emission over wetlands is needed for more precise future predictions. In this work, a set of high-latitude wetland sites with various nutrient conditions are studied. The wetland CH&lt;sub&gt;4&lt;/sub&gt; fluxes are simulated by the land surface model JULES of the UK Earth System model and the Helsinki peatland methane emission model (HIMMELI), which is developed at Finnish Meteorological Institute and Helsinki University. The differences between the modelled and observed CH&lt;sub&gt;4&lt;/sub&gt; fluxes are analyzed, complemented with key environmental variables for interpretation (e.g. soil temperature and moisture, vegetation types, snow depth, NPP, soil carbon). In general, the simulated CH&lt;sub&gt;4&lt;/sub&gt; fluxes by HIMMELI is closer to the observed CH&lt;sub&gt;4&lt;/sub&gt; fluxes in magnitude and seasonality at sites than those by JULES. The inter-annual variability of simulated CH&lt;sub&gt;4&lt;/sub&gt; fluxes by HIMMELI depends on the simulated anoxic soil respiration, which serves as the substrate of the CH&lt;sub&gt;4&lt;/sub&gt; fluxes in HIMMELI. The anoxic soil respiration is calculated based on the simulated soil respiration and water table depth in JULES. More accurate simulation of soil carbon pool and water table depth in JULES will lead to improvement in the simulated anoxic soil respiration.&lt;/p&gt;

Sign in / Sign up

Export Citation Format

Share Document