scholarly journals Temperature response functions introduce high uncertainty in modelled carbon stocks in cold temperature regimes

2010 ◽  
Vol 7 (11) ◽  
pp. 3669-3684 ◽  
Author(s):  
H. Portner ◽  
H. Bugmann ◽  
A. Wolf
Keyword(s):  
Soil Carbon ◽  
Elevation Gradient ◽  
Temperature Response ◽  
Terrestrial Ecosystems ◽  
Ecosystem Model ◽  
Carbon Stocks ◽  
Carbon Pools ◽  
Parameter Estimates ◽  
Response Functions ◽  
Data Set

Abstract. Models of carbon cycling in terrestrial ecosystems contain formulations for the dependence of respiration on temperature, but the sensitivity of predicted carbon pools and fluxes to these formulations and their parameterization is not well understood. Thus, we performed an uncertainty analysis of soil organic matter decomposition with respect to its temperature dependency using the ecosystem model LPJ-GUESS. We used five temperature response functions (Exponential, Arrhenius, Lloyd-Taylor, Gaussian, Van't Hoff). We determined the parameter confidence ranges of the formulations by nonlinear regression analysis based on eight experimental datasets from Northern Hemisphere ecosystems. We sampled over the confidence ranges of the parameters and ran simulations for each pair of temperature response function and calibration site. We analyzed both the long-term and the short-term heterotrophic soil carbon dynamics over a virtual elevation gradient in southern Switzerland. The temperature relationship of Lloyd-Taylor fitted the overall data set best as the other functions either resulted in poor fits (Exponential, Arrhenius) or were not applicable for all datasets (Gaussian, Van't Hoff). There were two main sources of uncertainty for model simulations: (1) the lack of confidence in the parameter estimates of the temperature response, which increased with increasing temperature, and (2) the size of the simulated soil carbon pools, which increased with elevation, as slower turn-over times lead to higher carbon stocks and higher associated uncertainties. Our results therefore indicate that such projections are more uncertain for higher elevations and hence also higher latitudes, which are of key importance for the global terrestrial carbon budget.

scholarly journals Temperature response functions introduce high uncertainty in modelled carbon stocks in cold temperature regimes

2009 ◽  
Vol 6 (4) ◽  
pp. 8129-8165 ◽  
Author(s):  
H. Portner ◽  
H. Bugmann ◽  
A. Wolf
Keyword(s):  
Organic Matter ◽  
Soil Organic Matter ◽  
Soil Carbon ◽  
Temperature Response ◽  
Carbon Stocks ◽  
Carbon Pools ◽  
Temperature Dependency ◽  
Response Functions ◽  
Soil Organic Matter Decomposition ◽  
Turn Over

Abstract. Models of carbon cycling in terrestrial ecosystems contain formulations for the dependence of respiration on temperature, but the sensitivity of predicted carbon pools and fluxes to these formulations and their parameterization is not understood. Thus, we made an uncertainty analysis of soil organic matter decomposition with respect to its temperature dependency using the ecosystem model LPJ-GUESS. We used five temperature response functions (Exponential, Arrhenius, Lloyd-Taylor, Gaussian, Van't Hoff). We determined the parameter uncertainty ranges of the functions by nonlinear regression analysis based on eight experimental datasets from northern hemisphere ecosystems. We sampled over the uncertainty bounds of the parameters and run simulations for each pair of temperature response function and calibration site. The uncertainty in both long-term and short-term soil carbon dynamics was analyzed over an elevation gradient in southern Switzerland. The function of Lloyd-Taylor turned out to be adequate for modelling the temperature dependency of soil organic matter decomposition, whereas the other functions either resulted in poor fits (Exponential, Arrhenius) or were not applicable for all datasets (Gaussian, Van't Hoff). There were two main sources of uncertainty for model simulations: (1) the uncertainty in the parameter estimates of the response functions, which increased with increasing temperature and (2) the uncertainty in the simulated size of carbon pools, which increased with elevation, as slower turn-over times lead to higher carbon stocks and higher associated uncertainties. The higher uncertainty in carbon pools with slow turn-over rates has important implications for the uncertainty in the projection of the change of soil carbon stocks driven by climate change, which turned out to be more uncertain for higher elevations and hence higher latitudes, which are of key importance for the global terrestrial carbon budget.

scholarly journals Impacts of Permafrost Degradation on Carbon Stocks and Emissions under a Warming Climate: A Review

Atmosphere ◽  
2021 ◽  
Vol 12 (11) ◽  
pp. 1425
Author(s):  
Huijun Jin ◽  
Qiang Ma
Keyword(s):  
Organic Carbon ◽  
Climate Warming ◽  
Carbon Emissions ◽  
Ecosystem Model ◽  
Carbon Stocks ◽  
Carbon Pools ◽  
Permafrost Degradation ◽  
Arctic Ecosystems ◽  
Warming Climate ◽  
Permafrost Regions

A huge amount of carbon (C) is stored in permafrost regions. Climate warming and permafrost degradation induce gradual and abrupt carbon emissions into both the atmosphere and hydrosphere. In this paper, we review and synthesize recent advances in studies on carbon stocks in permafrost regions, biodegradability of permafrost organic carbon (POC), carbon emissions, and modeling/projecting permafrost carbon feedback to climate warming. The results showed that: (1) A large amount of organic carbon (1460–1600 PgC) is stored in permafrost regions, while there are large uncertainties in the estimation of carbon pools in subsea permafrost and in clathrates in terrestrial permafrost regions and offshore clathrate reservoirs; (2) many studies indicate that carbon pools in Circum-Arctic regions are on the rise despite the increasing release of POC under a warming climate, because of enhancing carbon uptake of boreal and arctic ecosystems; however, some ecosystem model studies indicate otherwise, that the permafrost carbon pool tends to decline as a result of conversion of permafrost regions from atmospheric sink to source under a warming climate; (3) multiple environmental factors affect the decomposability of POC, including ground hydrothermal regimes, carbon/nitrogen (C/N) ratio, organic carbon contents, and microbial communities, among others; and (4) however, results from modeling and projecting studies on the feedbacks of POC to climate warming indicate no conclusive or substantial acceleration of climate warming from POC emission and permafrost degradation over the 21st century. These projections may potentially underestimate the POC feedbacks to climate warming if abrupt POC emissions are not taken into account. We advise that studies on permafrost carbon feedbacks to climate warming should also focus more on the carbon feedbacks from the rapid permafrost degradation, such as thermokarst processes, gas hydrate destabilization, and wildfire-induced permafrost degradation. More attention should be paid to carbon emissions from aquatic systems because of their roles in channeling POC release and their significant methane release potentials.

How useful are MIR predictions of total, particulate, humus, and resistant organic carbon for examining changes in soil carbon stocks in response to different crop management? A case study

Soil Research ◽  
2013 ◽  
Vol 51 (8) ◽  
pp. 719 ◽  
Author(s):  
K. L. Page ◽  
R. C. Dalal ◽  
Y. P. Dang
Keyword(s):  
Organic Carbon ◽  
Soil Carbon ◽  
Management Practices ◽  
Crop Management ◽  
Carbon Stocks ◽  
Carbon Pools ◽  
Spectroscopic Techniques ◽  
Direct Measurements ◽  
Soil Carbon Stocks

Measures of particulate organic carbon (POC), humus organic carbon (HOC), and resistant organic carbon (ROC) (primarily char) are often used to represent the active, slow, and inert carbon pools used in soil carbon models. However, these fractions are difficult to measure directly, and mid infrared (MIR) spectroscopic techniques are increasingly being investigated to quantify these fractions and total organic carbon (TOC). This study examined the change in MIR-predicted pools of TOC, POC, HOC, and ROC in response to different crop management between two time periods (1981 and 2008) in a long-term wheat cropping trial in Queensland, Australia. The aims were (i) to assess the ability of MIR to detect changes in carbon stocks compared with direct measurements of TOC (LECO-TOC); and (ii) to assess how well the behaviour of POC, HOC, and ROC corresponded with the active, slow, and inert conceptual carbon pools. Significant declines in carbon stocks were observed over time using both LECO-TOC and MIR-predicted stocks of TOC, POC, HOC, and ROC, although MIR-TOC under-estimated loss by 27–30% compared with LECO-TOC. The decline in MIR-POC and MIR-HOC was consistent with the expected behaviour of the active and slow conceptual pools; however, the decline in ROC was not consistent with that of the inert pool. In addition, MIR measurements did not accurately detect differences in the rate of carbon loss under different crop management practices.

scholarly journals Convergent modeling of past soil organic carbon stocks but divergent projections

2015 ◽  
Vol 12 (5) ◽  
pp. 4245-4272 ◽  
Author(s):  
Z. Luo ◽  
E. Wang ◽  
H. Zheng ◽  
J. A. Baldock ◽  
O. J. Sun ◽  
...  
Keyword(s):  
Soil Carbon ◽  
Field Experiments ◽  
Environmental Changes ◽  
Agricultural Soils ◽  
Terrestrial Ecosystems ◽  
Turnover Time ◽  
Carbon Stocks ◽  
Biogeochemical Model ◽  
Carbon Modeling ◽  
Carbon Composition

Abstract. Soil carbon models are important tool to understand soil carbon balance and project carbon stocks in terrestrial ecosystems, particularly under global change. The initialization and/or parameterization of soil carbon models can vary among studies even when the same model and dataset are used, causing potential uncertainties in projections. Although a few studies have assessed such uncertainties, it is yet unclear what these uncertainties are correlated with and how they change across varying environmental and management conditions. Here, applying a process-based biogeochemical model to 90 individual field experiments (ranging from 5 to 82 years of experimental duration) across the Australian cereal-growing regions, we demonstrated that well-designed calibration procedures enabled the model to accurately simulate changes in measured carbon stocks, but did not guarantee convergent forward projections (100 years). Major causes of the projection uncertainty were due to insufficient understanding of how microbial processes and soil carbon composition change to modulate carbon turnover. For a given site, the uncertainty significantly increased with the magnitude of future carbon input and years of the projection. Across sites, the uncertainty correlated positively with temperature, but negatively with rainfall. On average, a 331% uncertainty in projected carbon sequestration ability can be inferred in Australian agricultural soils. This uncertainty would increase further if projections were made for future warming and drying conditions. Future improvement in soil carbon modeling should focus on how microbial community and its carbon use efficiency change in response to environmental changes, better quantification of composition of soil carbon and its change, and how the soil carbon composition will affect its turnover time.

scholarly journals Potensi Simpanan Karbon pada Beberapa Tipologi Hutan Rawa Gambut di Kalimantan Tengah

2018 ◽  
Vol 12 (2) ◽  
pp. 196 ◽  
Author(s):  
Muhammad Abdul Qirom ◽  
Tri Wira Yuwati ◽  
Purwanto Budi Santosa ◽  
Wawan Halwany ◽  
Dony Rachmanadi
Keyword(s):  
Carbon Content ◽  
Soil Carbon ◽  
Conversion Factor ◽  
Secondary Forest ◽  
Dry Weight ◽  
Carbon Stocks ◽  
Total Carbon ◽  
Carbon Pools ◽  
Soil Carbon Pools ◽  
Soil Carbon Stocks

Akurasi pendugaan simpanan karbon hutan rawa gambut dapat ditingkatkan melalui pengukuran masing-masing gudang/sumber karbon dan berbagai macam tipologi hutannya. Pengukuran tersebut berkaitan dengan besarnya kandungan dan fraksi simpanan karbon pada masing-masing gudang karbon. Penelitian ini bertujuan untuk mendapatkan kandungan dan potensi simpanan karbon pada masing-masing gudang karbon di tipologi gambut. Pengukuran simpanan karbon dilakukan pada lima gudang karbon yakni vegetasi (tingkat permudaan pohon), serasah, tumbuhan bawah, nekromasa dan tanah. Hasil penelitian menunjukkan kandungan karbon adalah 50% dari berat kering biomassa. Kandungan karbon tidak dipengaruhi oleh gudang karbon dan tipologi gambut. Pada tanah gambut, kedalaman gambut mempengaruhi besarnya kandungan karbon sehingga besarnya faktor konversi harus memperhatikan kedalaman masing-masing tipologi gambut. Potensi simpanan karbon terbesar pada tipologi hutan sekunder dengan kedalaman gambut antara 3-3,5 m sebesar 3.722,08 Mg/ha sedangkan potensi simpanan karbon terendah pada tipologi semak belukar dengan kedalaman gambut 3-3,5 m sebesar 2243,49 Mg/ha. Pada hutan gambut, gudang karbon tanah menyumbang >95% dari simpanan karbon total. Gudang karbon nekromasa memberikan sumbangan simpanan karbon terkecil. Fraksi simpanan karbon pada masing-masing gudang karbon berturut-turut adalah tanah> vegetasi> serasah> tumbuhan bawah> nekromasa.Carbon Stocks Potential of Peatland Forests Typologies in Central KalimantanAbstractAccuracy of carbon stocks estimation can be enhanced by measuring each carbon pools in various forest peatland typologies. The carbon stocks measurement is associated with the amount of contents and fractions of carbon stocks. The research objectives were to obtain the information of carbon contents and carbon stocks potentials in each carbon pool in the peat typologies. Carbon stocks measurement was conducted in five carbon pools which were: vegetation (tree stages), litter, understory, necromass, and soil. The results showed that the carbon contents reached more than 50% of its dry weight. The carbon contents were not affected by the carbon pools and peat typologies. In the soil carbon pools, peat depth affected the amount of carbon content so that the magnitude of the conversion factor should concentrate to the depth of each peat typology. The greatest potential of carbon stocks was found in the secondary forest (3,733.08 Mg/ha) with the peat depths between 3-3.5 m, while the lowest potential of carbon stocks found in the bush typology (2243.49 Mg/ha) with the peat depths between 3-3.5 m. In the peat typology, soil carbon stocks contributed more than 95% of total carbon stocks whereas necromass carbon stocks contributed the smallest amount of carbon. The fractions of carbon stocks in each carbon pools were soil> vegetation> litter> understorey> necromass, respectively.

Soil organic matter build-up during soil formation in glacier forefields around the world

2020 ◽  
Author(s):  
Norine Khedim ◽  
Lauric Cécillon ◽  
Jérome Poulenard ◽  
Pierre Barré ◽  
François Baudin ◽  
...  
Keyword(s):  
Organic Matter ◽  
Soil Organic Matter ◽  
Soil Carbon ◽  
Total Concentration ◽  
Soil Formation ◽  
Terrestrial Ecosystems ◽  
Isotopic Signature ◽  
Carbon Pools ◽  
Soil Carbon Pools ◽  
The World

<p>Due to the continued ice retreat with global warming, areas of deglaciated forefields will strongly increase in the future, leading to the emergence of new terrestrial ecosystems in many regions of the world. The soil chronosequences resulting from glacier retreat have long been a key tool for studies focusing on the mechanisms of soil formation and soil organic matter storage.</p><p>This study aimed at identifying general patterns in soil organic matter (SOM) build-up during the initial stage of soil formation and ecosystem development (0–500 years) in different glacier forefields around the world. For this purpose, we measured total soil organic matter concentration (C and N), its stable isotopic composition (<sup>13</sup>C, <sup>15</sup>N) and its distribution in carbon pools of different biogeochemical stability over time in ten soil chronosequences on glacier forefields (four Andeans, one Canadian Rockies, one Greenland, two Alps, one Caucasus, one Himalaya). The distribution of SOM in carbon pools was estimated with Rock-Eval® thermal analysis. We then tested the effect of time and climatic variables (temperature, precipitation) on the build-up of soil organic matter (total concentration, isotopic signature and distribution in carbon pools).</p><p>We found a positive correlation between the rate of SOM accumulation and the average temperature of the warmest quarter (three-month period). We also noted significant traces of atmospheric deposition of anthropogenic origin in some forefield glaciers, particularly in the northern hemisphere. The build-up of soil carbon pools showed consistent trends across the soil chronosequences of the ten glacier forefields. During the first decades of soil formation, the very low SOM quantities were dominated by a very stable carbon with a small but significant labile carbon pool. This may highlight the presence of organic matter derived from ancient carbon on the different forefield glaciers, decomposed by an active living trophic network of soil microorganisms. The overall stability of SOM then slowly decreased with time, reflecting the soil carbon input from plants.</p><p>We conclude that while the rate of SOM accumulation is driven by climate (air temperature of the growing season), the build-up of soil carbon pools shows a consistent temporal trajectory on the different glacier forefields around the world.</p>

scholarly journals Climate legacies drive global soil carbon stocks in terrestrial ecosystems

2017 ◽  
Vol 3 (4) ◽  
pp. e1602008 ◽  
Author(s):  
Manuel Delgado-Baquerizo ◽  
David J. Eldridge ◽  
Fernando T. Maestre ◽  
Senani B. Karunaratne ◽  
Pankaj Trivedi ◽  
...  
Keyword(s):  
Soil Carbon ◽  
Terrestrial Ecosystems ◽  
Carbon Stocks ◽  
Global Soil ◽  
Soil Carbon Stocks
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