Assessing the response of soil carbon in Australia to changing inputs and climate using a consistent modelling framework

Abstract. Land use and management practices affect the response of soil organic carbon (C) to global change. Process-based models of soil C are useful tools to simulate C dynamics, but it is important to bridge any disconnect that exists between the data used to inform the models and the processes that they depict. To minimise that disconnect, we developed a consistent modelling framework that integrates new spatially explicit soil measurements and data with the Rothamsted carbon model (Roth C) and simulates the response of soil organic C to future climate change across Australia. We compiled publicly available continental-scale datasets and pre-processed, standardised and configured them to the required spatial and temporal resolutions. We then calibrated Roth C and ran simulations to estimate the baseline soil organic C stocks and composition in the 0–0.3 m layer at 4043 sites in cropping, modified grazing, native grazing and natural environments across Australia. We used data on the C fractions, the particulate, mineral-associated and resistant organic C (POC, MAOC and ROC, respectively) to represent the three main C pools in the Roth C model's structure. The model explained 97 %–98 % of the variation in measured total organic C in soils under cropping and grazing and 65 % in soils under natural environments. We optimised the model at each site and experimented with different amounts of C inputs to simulate the potential for C accumulation under constant climate in a 100-year simulation. With an annual increase of 1 Mg C ha−1 in C inputs, the model simulated a potential soil C increase of 13.58 (interquartile range 12.19–15.80), 14.21 (12.38–16.03) and 15.57 (12.07–17.82) Mg C ha−1 under cropping, modified grazing and native grazing and 3.52 (3.15–4.09) Mg C ha−1 under natural environments. With projected future changes in climate (+1.5, 2 and 5.0 ∘C) over 100 years, the simulations showed that soils under natural environments lost the most C, between 3.1 and 4.5 Mg C ha−1, while soils under native grazing lost the least, between 0.4 and 0.7 Mg C ha−1. Soil under cropping lost between 1 and 2.7 Mg C ha−1, while those under modified grazing showed a slight increase with temperature increases of 1.5 ∘C, but with further increases of 2 and 5 ∘C the median loss of TOC was 0.28 and 3.4 Mg C ha−1, respectively. For the different land uses, the changes in the C fractions varied with changes in climate. An empirical assessment of the controls on the C change showed that climate, pH, total N, the C : N ratio and cropping were the most important controls on POC change. Clay content and climate were dominant controls on MAOC change. Consistent and explicit soil organic C simulations improve confidence in the model's estimations, facilitating the development of sustainable soil management under global change.

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Simulation of soil carbon dynamics in Australia under a framework that better connects spatially explicit data with Rᴏᴛʜ C

10.5194/bg-2020-150 ◽

2020 ◽

Author(s):

Juhwan Lee ◽

Raphael A. Viscarra Rossel ◽

Zhongkui Luo ◽

Ying Ping Wang

Keyword(s):

C:N Ratio ◽

Clay Content ◽

Spatially Explicit ◽

Natural Environments ◽

Soil Organic C ◽

Total N ◽

Organic C ◽

Soil C ◽

Continental Scale ◽

C Stocks

Abstract. We simulated soil organic carbon (C) dynamics across Australia with the Rothamsted carbon model (Rᴏᴛʜ C) under a framework that connects new spatially-explicit soil measurements and data with the model. Doing so helped to bridge the disconnection that exists between datasets used to inform the model and the processes that it depicts. Under this framework, we compiled continental-scale datasets and pre-processed, standardised and configured them to the required spatial and temporal resolutions. We then calibrated Rᴏᴛʜ C and run simulations to predict the baseline soil organic C stocks and composition in the 0–0.3 m layer at 4,043 sites in cropping, modified grazing, native grazing, and natural environments across Australia. The Rᴏᴛʜ C model uses measured C fractions, the particulate, humus, and resistant organic C (POC, HOC and ROC, respectively) to represent the three main C pools in its structure. The model explained 97–98 % of the variation in measured total organic C in soils under cropping and grazing, and 65 % in soils under natural environments. We optimised the model at each site and experimented with different amounts of C inputs to predict the potential for C accumulation in a 100-year simulation. With an annual increase of 1 Mg C ha−1 in C inputs, the model predicted a potential soil C increase of 13.58 (interquartile range 12.19–15.80), 14.21 (12.38–16.03), and 15.57 (12.07–17.82) Mg C ha−1 under cropping, modified grazing and native grazing, and 3.52 (3.15–4.09) Mg C ha−1 under natural environments. Soils under native grazing were the most potentially vulnerable to C decomposition and loss, while soils under natural environments were the least vulnerable. An empirical assessment of the controls on the C change showed that climate, pH, total N, the C:N ratio, and cropping were the most important controls on POC change. Clay content and climate were dominant controls on HOC change. Consistent and explicit soil organic C simulations improve confidence in the model's predictions, contributing to the development of sustainable soil management under global change.

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Simulation of soil carbon dynamics in Australia with {\sc Roth C}

10.5194/ismc2021-91 ◽

2021 ◽

Author(s):

Raphael Viscarra Rossel ◽

Juhwan Lee ◽

Mingxi Zhang ◽

Zhongkui Luo ◽

YingPing Wang

Keyword(s):

C:N Ratio ◽

Clay Content ◽

Natural Environments ◽

Soil Organic C ◽

Total N ◽

Organic C ◽

Continental Scale ◽

C Stocks ◽

C Decomposition ◽

Soil Measurements

We simulated soil organic carbon (C) dynamics across Australia with the Rothamsted carbon model ({\sc Roth C}) by connecting new spatially-explicit soil measurements and data with the model. This helped us to bridge the disconnection that exists between datasets used to inform the model and the processes that it depicts. We compiled publicly available continental-scale datasets and pre-processed, standardised and configured them to the required spatial and temporal resolutions. We then calibrated {\sc Roth C} and run simulations to estimate the baseline soil organic C stocks and composition in the 0--0.3~m layer at 4,043 sites in cropping, modified grazing, native grazing, and natural environments across Australia. We used data on the C fractions, the particulate, mineral associated, and resistant organic C (POC, MAOC and ROC, respectively) to represent the three main C pools in the {\sc Roth C} model's structure.&#160; The model explained 97--98\% of the variation in measured total organic C in soils under cropping and grazing, and 65\% in soils under natural environments. We optimised the model at each site and experimented with different amounts of C inputs to simulate the potential for C accumulation under constant and chainging climate in a 100-year simulation. Soils under native grazing were the most potentially vulnerable to C decomposition and loss, while soils under natural environments were the least vulnerable. An empirical assessment of the controls on the C change showed that climate, pH, total N, the C:N ratio, and cropping were the most important controls on POC change. Clay content and climate were dominant controls on MAOC change. Consistent and explicit soil organic C simulations improve confidence in the model's estimations, contributing to the development of sustainable soil management under global change.&#160;

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Soil carbon and nitrogen in pasture soil reforested with eucalyptus and guachapele

Revista Brasileira de Ciência do Solo ◽

10.1590/s0100-06832008000300033 ◽

2008 ◽

Vol 32 (3) ◽

pp. 1253-1260 ◽

Cited By ~ 33

Author(s):

Fabiano de Carvalho Balieiro ◽

Marcos Gervasio Pereira ◽

Bruno José Rodrigues Alves ◽

Alexander Silva de Resende ◽

Avílio Antonio Franco

Keyword(s):

Panicum Maximum ◽

Soil Organic C ◽

Total N ◽

Organic C ◽

Soil C ◽

C Stocks ◽

Soil C And N ◽

C And N ◽

Mixed Plantation ◽

The Impact

In spite of the normally low content of organic matter found in sandy soils, it is responsible for almost the totality of cation exchange capacity (CEC), water storage and availability of plant nutrients. It is therefore important to evaluate the impact of alternative forest exploitation on the improvement of soil C and N accumulation on these soils. This study compared pure and mixed plantations of Eucalyptus grandis and Pseudosamanea guachapele, a N2-fixing leguminous tree, in relation to their effects on soil C and N stocks. The studied Planosol area had formerly been covered by Panicum maximum pasture for at least ten years without any fertilizer addition. To estimate C and N contents, the soil was sampled (at depths of 0-2.5; 2.5-5.0; 5.0-7.5; 7.5-10.0; 10.0-20.0 and 20.0-40.0 cm), in pure and mixed five-year-old tree plantations, as well as on adjacent pasture. The natural abundance 13C technique was used to estimate the contribution of the soil organic C originated from the trees in the 0-10 cm soil layer. Soil C and N stocks under mixed plantation were 23.83 and 1.74 Mg ha-1, respectively. Under guachapele, eucalyptus and pasture areas C stocks were 14.20, 17.19 and 24.24 Mg ha-1, respectively. For these same treatments, total N contents were 0.83; 0.99 and 1.71 Mg ha-1, respectively. Up to 40 % of the soil organic C in the mixed plantation was estimated to be derived from trees, while in pure eucalyptus and guachapele plantations these same estimates were only 19 and 27 %, respectively. Our results revealed the benefits of intercropped leguminous trees in eucalyptus plantations on soil C and N stocks.

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Evaluation of terrestrial pan-Arctic carbon cycling using a data-assimilation system

Earth System Dynamics ◽

10.5194/esd-10-233-2019 ◽

2019 ◽

Vol 10 (2) ◽

pp. 233-255 ◽

Cited By ~ 4

Author(s):

Efrén López-Blanco ◽

Jean-François Exbrayat ◽

Magnus Lund ◽

Torben R. Christensen ◽

Mikkel P. Tamstorf ◽

...

Keyword(s):

The Arctic ◽

Soil Organic C ◽

Area Index ◽

Organic C ◽

Soil C ◽

Transit Times ◽

C Cycle ◽

C Stocks ◽

Data Assimilation System ◽

Assimilation System

Abstract. There is a significant knowledge gap in the current state of the terrestrial carbon (C) budget. Recent studies have highlighted a poor understanding particularly of C pool transit times and of whether productivity or biomass dominate these biases. The Arctic, accounting for approximately 50 % of the global soil organic C stocks, has an important role in the global C cycle. Here, we use the CARbon DAta MOdel (CARDAMOM) data-assimilation system to produce pan-Arctic terrestrial C cycle analyses for 2000–2015. This approach avoids using traditional plant functional type or steady-state assumptions. We integrate a range of data (soil organic C, leaf area index, biomass, and climate) to determine the most likely state of the high-latitude C cycle at a 1∘ × 1∘ resolution and also to provide general guidance about the controlling biases in transit times. On average, CARDAMOM estimates regional mean rates of photosynthesis of 565 g C m−2 yr−1 (90 % confidence interval between the 5th and 95th percentiles: 428, 741), autotrophic respiration of 270 g C m−2 yr−1 (182, 397) and heterotrophic respiration of 219 g C m−2 yr−1 (31, 1458), suggesting a pan-Arctic sink of −67 (−287, 1160) g Cm−2 yr−1, weaker in tundra and stronger in taiga. However, our confidence intervals remain large (and so the region could be a source of C), reflecting uncertainty assigned to the regional data products. We show a clear spatial and temporal agreement between CARDAMOM analyses and different sources of assimilated and independent data at both pan-Arctic and local scales but also identify consistent biases between CARDAMOM and validation data. The assimilation process requires clearer error quantification for leaf area index (LAI) and biomass products to resolve these biases. Mapping of vegetation C stocks and change over time and soil C ages linked to soil C stocks is required for better analytical constraint. Comparing CARDAMOM analyses to global vegetation models (GVMs) for the same period, we conclude that transit times of vegetation C are inconsistently simulated in GVMs due to a combination of uncertainties from productivity and biomass calculations. Our findings highlight that GVMs need to focus on constraining both current vegetation C stocks and net primary production to improve a process-based understanding of C cycle dynamics in the Arctic.

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Douglas-fir soil C and N properties a decade after termination of urea fertilization

Canadian Journal of Forest Research ◽

10.1139/x01-162 ◽

2001 ◽

Vol 31 (12) ◽

pp. 2225-2236 ◽

Cited By ~ 23

Author(s):

Peter S Homann ◽

Bruce A Caldwell ◽

H N Chappell ◽

Phillip Sollins ◽

Chris W Swanston

Keyword(s):

Mineral Soil ◽

Cellulase Activity ◽

Douglas Fir ◽

Soil Organic C ◽

Total N ◽

Organic C ◽

Soil C ◽

Second Growth ◽

Heavy Fractions ◽

Urea Fertilization

Chemical and microbial soil properties were assessed in paired unfertilized and urea fertilized (>89 g N·m2) plots in 13 second-growth Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco) stands distributed throughout western Washington and Oregon. A decade following the termination of fertilization, fertilized plots averaged 28% higher total N in the O layer than unfertilized plots, 24% higher total N in surface (05 cm) mineral soil, and up to four times the amount of extractable ammonium and nitrate. Decreased pH (0.2 pH units) caused by fertilization may have been due to nitrification or enhanced cation uptake. In some soil layers, fertilization decreased cellulase activity and soil respiration but increased wood decomposition. There was no effect of fertilization on concentrations of light and heavy fractions, labile carbohydrates, and phosphatase and xylanase activities. No increase in soil organic C was detected, although variability precluded observing an increase of less than ~15%. Lack of a regionwide fertilization influence on soil organic C contrasts with several site-specific forest and agricultural studies that have shown C increases resulting from fertilization. Overall, the results indicate a substantial residual influence on soil N a decade after urea fertilization but much more limited influence on soil C processes and pools.

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Soil carbon stocks and their variability across the forests, shrublands and grasslands of peninsular Spain

Biogeosciences ◽

10.5194/bg-10-8353-2013 ◽

2013 ◽

Vol 10 (12) ◽

pp. 8353-8361 ◽

Cited By ~ 25

Author(s):

E. Doblas-Miranda ◽

P. Rovira ◽

L. Brotons ◽

J. Martínez-Vilalta ◽

J. Retana ◽

...

Keyword(s):

Global Change ◽

Vegetation Cover ◽

Field Measurements ◽

Annual Precipitation ◽

Future Climate Change ◽

Mean Annual Temperature ◽

Soil C ◽

C Stocks ◽

The Impact ◽

Peninsular Spain

Abstract. Accurate estimates of C stocks and fluxes of soil organic carbon (SOC) are needed to assess the impact of climate and land use change on soil C uptake and soil C emissions to the atmosphere. Here, we present an assessment of SOC stocks in forests, shrublands and grasslands of peninsular Spain based on field measurements in more than 900 soil profiles. SOC to a depth of 1 m was modelled as a function of vegetation cover, mean annual temperature, total annual precipitation, elevation and the interaction between temperature and elevation, while latitude and longitude were used to model the correlation structure of the errors. The resulting statistical model was used to estimate SOC in the ∼8 million pixels of the Spanish Forest Map (29.3 × 106 ha). We present what we believe is the most reliable estimation of current SOC in forests, shrublands and grasslands of peninsular Spain thus far, based on the use of spatial modelling, the high number of profiles and the validity and refinement of the data layers employed. Mean concentration of SOC was 8.7 kg m−2, ranging from 2.3 kg m−2 in dry Mediterranean areas to 20.4 kg m−2 in wetter northern locations. This value corresponds to a total stock of 2.544 Tg SOC, which is four times the amount of C estimated to be stored in the biomass of Spanish forests. Climate and vegetation cover were the main variables influencing SOC, with important ecological implications for peninsular Spanish ecosystems in the face of global change. The fact that SOC was positively related to annual precipitation and negatively related to mean annual temperature suggests that future climate change predictions of increased temperature and reduced precipitation may strongly reduce the potential of Spanish soils as C sinks. However, this may be mediated by changes in vegetation cover (e.g. by favouring the development of forests associated to higher SOC values) and exacerbated by perturbations such as fire. The estimations presented here provide a baseline to estimate future changes in soil C stocks and to assess their vulnerability to key global change drivers, and should inform future actions aimed at the conservation and management of C stocks.

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Soil carbon stocks and their variability across the woodlands of peninsular Spain

Biogeosciences Discussions ◽

10.5194/bgd-10-10913-2013 ◽

2013 ◽

Vol 10 (7) ◽

pp. 10913-10936

Author(s):

E. Doblas-Miranda ◽

P. Rovira ◽

L. Brotons ◽

J. Martínez-Vilalta ◽

J. Retana ◽

...

Keyword(s):

Global Change ◽

Vegetation Cover ◽

Carbon Stocks ◽

Annual Precipitation ◽

Future Climate Change ◽

Mean Annual Temperature ◽

Soil C ◽

C Stocks ◽

The Impact ◽

Peninsular Spain

Abstract. Global warming effects in our ecosystems could be offset by reducing carbon emissions and protecting and increasing carbon stocks. Accurate estimates of carbon stocks and fluxes of soil organic carbon (SOC) are thus needed to asses the impact of climate and land-use change on soil C uptake and soil C emissions to the atmosphere. Here, we present an assessment of SOC stocks in woodlands (forest, shrublands and grasslands) of peninsular Spain based on field measurements in more than 900 soil profiles. Estimations of soil C stocks for the 7 796 306 plots of the Spanish Forest Map (24.3 × 106 ha.) were carried out using a statistical model that included, as explanatory variables, vegetation cover, parent material, soil consistency, mean annual temperature, total annual precipitation and elevation, and the influence of spatial correlation. We present what we believe is the most reliable estimation of current SOC in woodlands of peninsular Spain thus far, based on the considered predictors, the high number of profiles and the validity and refinement of the data layers employed. Mean concentration of SOC was 8.8 kg m−2, which is slightly higher than that presented in previous studies. This value corresponds to a total stock of 2574 Tg SOC, which is four times the amount of carbon estimated to be stored in the biomass of Spanish forests. Climate and vegetation cover were the main variables influencing SOC, with important ecological implications for peninsular Spanish ecosystems in the face of global change. The fact that SOC was positively related to annual precipitation and negatively related to mean annual temperature suggests that future climate change may strongly reduce the potential of Spanish soils as carbon sinks. However, this may be mediated by changes in vegetation cover (e.g., by favouring the development of forests associated to higher SOC values) and threatened by perturbations such as fire. The estimations presented here should improve our capacity to respond to global change by carbon stocks conservation and management.

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ANALISIS PERUBAHAN CADANGAN HARA PADA BERBAGAI PENGGUNAAN LAHAN DAN KELERENGAN DI DAS MIKRO KALI KUNGKUK, KOTA BATU

Jurnal Tanah dan Sumberdaya Lahan ◽

10.21776/ub.jtsl.2021.008.1.1 ◽

2020 ◽

Vol 8 (1) ◽

pp. 1-8

Author(s):

Refki Aulia Wiwaha ◽

Syahrul Kurniawan

Keyword(s):

Soil Nutrient ◽

Apple Orchard ◽

Forest Conversion ◽

Land Uses ◽

Soil Organic C ◽

Total N ◽

Organic C ◽

Soil C ◽

Soil C And N ◽

C And N

The Kali Kungkuk micro watershed which is located in the upper area of Brantas watershed, had experienced forest conversion to horticulture during the last fourth decades. Since the physiographic of Kali Kungkuk micro watershed is hilly, forest conversion to horticulture may result in soil nutrient stock changes. The research aimed to analyze soil nutrient stock from forest to horticulture land uses (i.e. apple orchard and vegetables) in the Kali Kungkuk micro watershed. The field research was conducted on three different land uses (i.e. vegetable land (PK), apple orchard (PA), and forest (PH)) and four land slope classes (i.e. slope 0-8% (K1), 8-15% (K2), 15-25% (K3), and > 25% (K4)), with three, replicates plots of each. Soil samples were collected at three different depths (0-10, 10-30, and 30- 50 cm) from each plot. The parameters measured included soil texture, bulk density, standing litter mass, canopy cover, basal area, soil organic carbon and total nitrogen. Data analysis was conducted with Linear Mixed Effect Models with a level of 5% and a further analysis of LSD test level of 5% as well as a correlation test between observational parameters. The results showed that differences in land use and slope affected to significant differences in the content of soil organic C and total N. In general, forests had higher soil C and N stocks as compared to other land uses (i.e. apple orchard and vegetables). Furthermore, soil organic C and total N was higher in the low slopes (i.e. 0-8%) and (8-15%) as compared to the high slopes (i.e. 15-25%) and (> 25%). The study found a positive correlation between soil nutrient stocks (i.e. C and N) and clay content. In contrast, soil C and N stock was negatively correlated with soil bulk density. Soil fertility degradation that occurs in the Kali Kungkuk micro watershed (i.e. apple orchard and vegetables) requires serious attention in soil management in order to ensure the sustainability of apple and vegetable production.

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Change in soil organic carbon and nitrogen stocks eight years after conversion of sub-humid grassland to Pinus and Eucalyptus forestry

Soil Research ◽

10.1071/sr17171 ◽

2018 ◽

Vol 56 (3) ◽

pp. 318 ◽

Cited By ~ 6

Author(s):

R. M. Lebenya ◽

C. W. van Huyssteen ◽

C. C. du Preez

Keyword(s):

Organic Carbon ◽

Soil Organic Carbon ◽

Soil Layer ◽

Pinus Elliottii ◽

Soil Organic C ◽

Soil Drainage ◽

Total N ◽

Organic C ◽

Drainage Class ◽

C Stocks

Scientific studies report decreases, increases, or negligible changes in soil organic carbon (C) stocks upon afforestation; however, these studies neglect the potential role of total nitrogen (N), tree species, and soil drainage class on these changes. This paper therefore aimed to quantify the change in soil organic C and total N stocks in the Weatherley catchment, eight years after conversion of grassland to forestry. Twenty-seven soil profile sites in this catchment, situated in the north-eastern corner of the Eastern Cape Province of South Africa, were sampled to determine the soil organic C and total N concentrations for the estimation of stocks. These sites represented different vegetation (Pinus elliottii, P. patula, Eucalyptus nitens, and grass) and soil drainage class (poorly, moderately, and freely drained soils) areas. Eighteen of the 27 sites studied had decreases, and nine sites had increases in organic C stocks in the 0–300 mm soil layer after eight years of afforestation. Total N decreased in 18 sites and increased at nine sites. Eight years of afforestation with P. elliottii and E. nitens significantly decreased stocks of soil organic C (from 47.6 to 38.8 Mg/ha) and total N (from 3.22 to 2.87 Mg/ha), whereas P. patula only slightly increased the corresponding stocks from 43.8 to 48.6 Mg C/ha and from 2.80 to 3.68 Mg N/ha. Both soil organic C and total N stocks decreased in all three soil drainage classes upon afforestation. It is proposed that these findings be corroborated after another 8–10 years of afforestation.

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Soil temperatures and active carbon components as key drivers of C stock dynamics between two different stand ages of Larix principis-rupprechtii plantation

PeerJ ◽

10.7717/peerj.8384 ◽

2020 ◽

Vol 8 ◽

pp. e8384

Author(s):

Junyong Ma ◽

Hairong Han ◽

Xiaoqin Cheng

Keyword(s):

Soil Temperature ◽

Soil Layer ◽

Microbial Biomass C ◽

Soil Organic C ◽

Total N ◽

Organic C ◽

Soil C ◽

Growing Seasons ◽

Soil Temperatures ◽

C And N

Forest soils sequester a large amount of carbon (C) and have a significant effect on the global C balance. Forests are commonly managed to maintain certain age structures but the effects of this management on soil C pools (kg C m−2) is still uncertain. We compared 40-year-old (1GF) and 24-year-old (2GF) plantations of Larix principis-rupprechtii in North China. Specifically, we measured environmental factors (e.g., soil temperature, moisture, and pH), the active C and nitrogen (N) pools (e.g., soil organic C, soil total N, dissolved organic C and N, microbial biomass C and N), and soil processes (e.g., C mineralization and microbial activity in different seasons) in five soil layers (0–50 cm, 10 cm for each soil layer) across the growing seasons in three 25 m × 25 m plots in each age class (1GF and 2GF). Findings indicated that the soil organic C pool in the older 1GF forest (12.43 kg C m−2) was significantly higher than 2GF forests (9.56 kg C m−2), and that soil temperature in 1GF forests was 9.8 °C, on average, 2.9% warmer than temperature in 2GF forests. The C lost as carbon dioxide (CO2) as a result of mineralization in the 2GF plots may partly explain the lower soil organic C pool in these younger forests; microorganisms likely drive this process.

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