scholarly journals CoupModel (v6.0): an ecosystem model for coupled phosphorus, nitrogen, and carbon dynamics – evaluated against empirical data from a climatic and fertility gradient in Sweden

2021 ◽  
Vol 14 (2) ◽  
pp. 735-761
Author(s):  
Hongxing He ◽  
Per-Erik Jansson ◽  
Annemieke I. Gärdenäs
Keyword(s):  
Terrestrial Ecosystems ◽  
C Sequestration ◽  
Forest Growth ◽  
N Leaching ◽  
Mean Annual Temperature ◽  
Soil N ◽  
Soil C ◽  
Fertility Gradient ◽  
Plant P Uptake ◽  
P Cycle

Abstract. This study presents the integration of the phosphorus (P) cycle into CoupModel (v6.0, referred to as Coup-CNP). The extended Coup-CNP, which explicitly considers the symbiosis between soil microbes and plant roots, enables simulations of coupled carbon (C), nitrogen (N), and P dynamics for terrestrial ecosystems. The model was evaluated against observed forest growth and measured leaf C∕P, C∕N, and N∕P ratios in four managed forest regions in Sweden. The four regions form a climatic and fertility gradient from 64∘ N (northern Sweden) to 56∘ N (southern Sweden), with mean annual temperature varying from 0.7–7.1 ∘C and soil C∕N and C∕P ratios varying between 19.8–31.5 and 425–633, respectively. The growth of the southern forests was found to be P-limited, with harvested biomass representing the largest P losses over the studied rotation period. The simulated P budgets revealed that southern forests are losing P, while northern forests have balanced P budgets. Symbiotic fungi accounted for half of total plant P uptake across all four regions, which highlights the importance of fungal-tree interactions in Swedish forests. The results of a sensitivity analysis demonstrated that optimal forest growth occurs at a soil N∕P ratio between 15–20. A soil N∕P ratio above 15–20 will result in decreased soil C sequestration and P leaching, along with a significant increase in N leaching. The simulations showed that Coup-CNP could describe shifting from being mostly N-limited to mostly P-limited and vice versa. The potential P-limitation of terrestrial ecosystems highlights the need for biogeochemical ecosystem models to consider the P cycle. We conclude that the inclusion of the P cycle enabled the Coup-CNP to account for various feedback mechanisms that have a significant impact on ecosystem C sequestration and N leaching under climate change and/or elevated N deposition.

scholarly journals CoupModel (v6.0): an ecosystem model for coupled phosphorus, nitrogen and carbon dynamics – evaluated against empirical data from a climatic and fertility gradient in Sweden

2020 ◽  
Author(s):  
Hongxing He ◽  
Per-Erik Jansson ◽  
Annemieke Gärdenäs
Keyword(s):  
Climate Change ◽  
Terrestrial Ecosystems ◽  
C Sequestration ◽  
Forest Growth ◽  
N Leaching ◽  
P Availability ◽  
Soil N ◽  
Soil C ◽  
Fertility Gradient ◽  
P Cycle

Abstract. This study presents the integration of the phosphorus (P) cycle into CoupModel (Coup-CNP). The extended Coup-CNP enables simulations of coupled carbon (C), nitrogen (N) and P dynamics for terrestrial ecosystems which explicitly consider mycorrhizal interactions. The model was evaluated against observed forest growth and measured leaf C/P, C/N and N/P ratios in four managed forest regions in Sweden. The four regions form a climatic and fertility gradient from 64° N in the North to 56° N in South Sweden with the mean annual temperature varying between 0.7–7.1 °C and the soil C/N and C/P ratios between 19.8–31.5 and 425–633, respectively. The growth of the southern forests was found to be P-limited, with harvested biomass representing the largest P loss over the studied rotation period. The simulated P budgets revealed that southern forests are losing P while northern forests are close to a steady state in P availability. Mycorrhizal fungi account for half of the total plant P uptake across all four regions, which highlights the importance of fungal-tree interactions in Swedish forests. Sensitivity analysis results demonstrated that the highest forest growth occurs at a soil N/P ratio of 15 to 20. A soil N/P ratio above 15–20 resulted in decreased soil C sequestration and total P leaching, but significantly increased N leaching. The development and evaluation of the new Coup-CNP model demonstrate that P fluxes need to be further considered in studies of how climate change will influence C turnover and ecosystem responses. We conclude that the potential P-limitation of terrestrial ecosystems highlights the need of a proper consideration of the P cycle in biogeochemical models. The inclusion of the P cycle is necessary in order to make models reliable tools for assessing long-term impacts of climate change and N deposition on C sequestration and N leaching.

Carbon stocks in Tasmanian soils

Soil Research ◽  
2012 ◽  
Vol 50 (2) ◽  
pp. 83 ◽  
Author(s):  
W. E. Cotching
Keyword(s):  
Management Practices ◽  
Agricultural Soils ◽  
C Sequestration ◽  
Mean Annual Temperature ◽  
Soil C ◽  
C Stocks ◽  
Initial Soil ◽  
If Current ◽  
Intensive Cropping ◽  
The Difference

Soil carbon (C) stocks were calculated for Tasmanian soil orders to 0.3 and 1.0 m depth from existing datasets. Tasmanian soils have C stocks of 49–117 Mg C/ha in the upper 0.3 m, with Ferrosols having the largest soil C stocks. Mean soil C stocks in agricultural soils were significantly lower under intensive cropping than under irrigated pasture. The range in soil C within soil orders indicates that it is critical to determine initial soil C stocks at individual sites and farms for C accounting and trading purposes, because the initial soil C content will determine if current or changed management practices are likely to result in soil C sequestration or emission. The distribution of C within the profile was significantly different between agricultural and forested land, with agricultural soils having two-thirds of their soil C in the upper 0.3 m, compared with half for forested soils. The difference in this proportion between agricultural and forested land was largest in Dermosols (0.72 v. 0.47). The total amount of soil C in a soil to 1.0 m depth may not change with a change in land use, but the distribution can and any change in soil C deeper in the profile might affect how soil C can be managed for sequestration. Tasmanian soil C stocks are significantly greater than those in mainland states of Australia, reflecting the lower mean annual temperature and higher precipitation in Tasmania, which result in less oxidation of soil organic matter.

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

2015 ◽  
Vol 12 (14) ◽  
pp. 4373-4383 ◽  
Author(s):  
Z. Luo ◽  
E. Wang ◽  
H. Zheng ◽  
J. A. Baldock ◽  
O. J. Sun ◽  
...  
Keyword(s):  
Field Experiments ◽  
Environmental Changes ◽  
Agricultural Soils ◽  
Terrestrial Ecosystems ◽  
C Sequestration ◽  
Biogeochemical Model ◽  
Data Set ◽  
Soil C ◽  
C Stocks ◽  
Drying Conditions

Abstract. Soil carbon (C) models are important tools for understanding soil C balance and projecting C stocks in terrestrial ecosystems, particularly under global change. The initialization and/or parameterization of soil C models can vary among studies even when the same model and data set 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 optimization procedures enabled the model to accurately simulate changes in measured C 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 C pool change to modulate C turnover. For a given site, the uncertainty significantly increased with the magnitude of future C 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 C 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 C modelling should focus on how the microbial community and its C use efficiency change in response to environmental changes, and better conceptualization of heterogeneous soil C pools and the C transformation among those pools.

scholarly journals Effects of AtmosphericCO2Enrichment on SoilCO2Efflux in a Young Longleaf Pine System

2012 ◽  
Vol 2012 ◽  
pp. 1-9 ◽  
Author(s):  
G. Brett Runion ◽  
J. R. Butnor ◽  
S. A. Prior ◽  
R. J. Mitchell ◽  
H. H. Rogers
Keyword(s):  
Soil Temperature ◽  
Atmospheric Carbon Dioxide ◽  
Continuous Monitoring ◽  
Longleaf Pine ◽  
Terrestrial Ecosystems ◽  
C Sequestration ◽  
Soil C ◽  
System A ◽  
C Dynamics ◽  
Response To Temperature

The southeastern landscape is composed of agricultural and forest systems that can store carbon (C) in standing biomass and soil. Research is needed to quantify the effects of elevated atmospheric carbon dioxide (CO2) on terrestrial C dynamics including CO2release back to the atmosphere and soil sequestration. Longleaf pine savannahs are an ecologically and economically important, yet understudied, component of the southeastern landscape. We investigated the effects of ambient and elevated CO2on soil CO2efflux in a young longleaf pine system using a continuous monitoring system. A significant increase (26.5%) in soil CO2efflux across 90 days was observed under elevated CO2; this occurred for all weekly and daily averages except for two days when soil temperature was the lowest. Soil CO2efflux was positively correlated with soil temperature with a trend towards increased efflux response to temperature under elevated CO2. Efflux was negatively correlated with soil moisture and was best represented using a quadratic relationship. Soil CO2efflux was not correlated with root biomass. Our data indicate that, while elevated CO2will increase feedback of CO2to the atmosphere via soil efflux, terrestrial ecosystems will remain potential sinks for atmospheric CO2due to greater biomass production and increased soil C sequestration.

scholarly journals Root biomass responses to elevated CO<sub>2</sub> limit soil C sequestration in managed grasslands

2012 ◽  
Vol 9 (1) ◽  
pp. 357-386 ◽  
Author(s):  
W. M. A. Sillen ◽  
W. I. J. Dieleman
Keyword(s):  
Elevated Co2 ◽  
Nitrogen Fertilization ◽  
Root Biomass ◽  
Terrestrial Ecosystems ◽  
C Sequestration ◽  
Soil C ◽  
C Storage ◽  
Co2 Concentrations ◽  
Soil C Storage ◽  
Co2 Elevation

Abstract. Elevated atmospheric CO2 levels and increasing nitrogen deposition both stimulate plant production in terrestrial ecosystems. Moreover, nitrogen deposition could alleviate an increasing nitrogen limitation experienced by plants exposed to elevated CO2 concentrations. However, an increased rate of C flux through the soil compartment as a consequence of elevated CO2 concentrations has been suggested to limit C sequestration in terrestrial ecosystems, questioning the potential for terrestrial C uptake to mitigate the increasing atmospheric CO2 concentrations. Our study used data from 69 published studies to investigate whether CO2 elevation and/or nitrogen fertilization could induce an increased carbon storage in grasslands, and considered the influence of management practices involving biomass removal or irrigation on the elevated CO2 effects. Our results confirmed a positive effect of elevated CO2 levels and nitrogen fertilization on plant growth, but revealed that N availability is essential for the increased C influx under elevated CO2 to propagate into belowground C pools. However, moderate nutrient additions also promoted decomposition processes in elevated CO2, reducing the potential for increased soil C storage. An important role in the soil carbon response to elevated CO2 was attributed to the root response, since there was a lower potential for increases in soil C content when root biomass was more responsive to CO2 elevation. Future elevated CO2 concentrations and increasing N deposition might thus increase C storage in plant biomass, but the potential for increased soil C storage is limited.

scholarly journals Quantifying Soil Carbon Accumulation in Alaskan Terrestrial Ecosystems during the Last 15,000 Years

2016 ◽  
Author(s):  
Sirui Wang ◽  
Qianlai Zhuang ◽  
Zicheng Yu
Keyword(s):  
20Th Century ◽  
Average Rate ◽  
Terrestrial Ecosystems ◽  
C Sequestration ◽  
Carbon Accumulation ◽  
Soil C ◽  
The Holocene ◽  
Holocene Thermal Maximum ◽  
Soil Carbon Accumulation ◽  
Climate Cooling

Abstract. Abstract: Northern high latitudes contain large amounts of soil organic carbon (SOC), in which Alaskan terrestrial ecosystems account for a substantial proportion. In this study, the SOC accumulation in Alaskan terrestrial ecosystems over the last 15,000 years was simulated using a process-based biogeochemistry model for both peatland and non-peatland terrestrial ecosystems. Comparable with the previous estimates of 25–70 Pg C in peatland and 13–22 Pg C in non-peatland soils within 1 m depth in Alaska, our model estimated a total SOC of 36–63 Pg C at present, including 27–48 Pg C in peatland soils and 9–15 Pg C in non-peatland soils. Vegetation stored only 2.5–3.7 Pg C in Alaska currently with 0.3–0.6 Pg C in peatlands and 2.2–3.1 Pg C in non-peatlands. The simulated average rate of peat C sequestration was 2.3 Tg C yr−1 with a peak value of 5.1 Tg C yr−1 during the Holocene Thermal Maximum (HTM) in the early Holocene, four folds higher than the average rate of 1.4 Tg C yr−1 over the rest of the Holocene. The SOC accumulation slowed down, or even ceased, during the neoglacial climate cooling after the mid-Holocene, but accumulation increased again in the 20th century. The model-estimated peat depths ranged from 1.1 to 2.7 m, similar to the field-based estimate of 2.29 m for the region. We found that the changes in vegetation types and their distributions due to climate change were the main factors determining the spatial variations of SOC accumulation during different time periods. Warmer summer temperature and stronger radiation seasonality, along with higher precipitation in the HTM and the 20th century might have resulted in the extensive peatland expansion and carbon accumulation, implying that soil C accumulation would continue under future warming conditions.

scholarly journals Carbon stocks and soil sequestration rates of riverine mangroves and freshwater wetlands

2015 ◽  
Vol 12 (2) ◽  
pp. 1015-1045 ◽  
Author(s):  
M. F. Adame ◽  
N. S. Santini ◽  
C. Tovilla ◽  
A. Vázquez-Lule ◽  
L. Castro
Keyword(s):  
Carbon Dioxide Emissions ◽  
Biosphere Reserve ◽  
C Sequestration ◽  
Freshwater Wetlands ◽  
Soil N ◽  
Riverine Wetlands ◽  
Soil C ◽  
C Stocks ◽  
Soil Accumulation ◽  
Soil C Sequestration

Abstract. Deforestation and degradation of wetlands are important causes of carbon dioxide emissions to the atmosphere. Accurate measurements of carbon (C) stocks and sequestration rates are needed for incorporating wetlands into conservation and restoration programs with the aim for preventing carbon emissions. Here, we assessed whole ecosystem C stocks (trees, soil and downed wood) and soil N stocks of riverine wetlands (mangroves, marshes and peat swamps) within La Encrucijada Biosphere Reserve in the Pacific coast of Mexico. We also estimated soil C sequestration rates of mangroves on the basis of soil accumulation. We hypothesized that riverine wetlands have large C stocks, and that upland mangroves have larger C and soil N stocks compared to lowland mangroves. Riverine wetlands had large C stocks with a mean of 784.5 ± 73.5 Mg C ha-1 for mangroves, 722.2 ± 83.4 Mg C ha-1 for peat swamps, and 336.5 ± 38.3 Mg C ha-1 for marshes. C stocks and soil N stocks were in general larger for upland (833.0 ± 7.2 Mg C ha-1; 26.4 ± 0.5 Mg N ha-1) compared to lowland mangroves (659.5 ± 18.6 Mg C ha-1; 13.8 ± 2.0 Mg N ha-1). Soil C sequestration values were 1.3 ± 0.2 Mg C ha-1 yr-1. The Reserve stores 32.5 Mtons of C or 119.3 Mtons of CO2, with mangroves sequestering (via soil accumulation) 27 762 ± 0.5 Mg C ha-1 every year.

scholarly journals Effects of two wood-based biochars on the fate of added fertilizer nitrogen—a 15N tracing study

2021 ◽  
Author(s):  
Subin Kalu ◽  
Gboyega Nathaniel Oyekoya ◽  
Per Ambus ◽  
Priit Tammeorg ◽  
Asko Simojoki ◽  
...  
Keyword(s):  
Plant Uptake ◽  
Plant Biomass ◽  
Application Rate ◽  
Control Treatment ◽  
Organic N ◽  
N Leaching ◽  
Soil N ◽  
Mineral N ◽  
Total N ◽  
Application Rates

AbstractA 15N tracing pot experiment was conducted using two types of wood-based biochars: a regular biochar and a Kon-Tiki-produced nutrient-enriched biochar, at two application rates (1% and 5% (w/w)), in addition to a fertilizer only and a control treatment. Ryegrass was sown in pots, all of which except controls received 15N-labelled fertilizer as either 15NH4NO3 or NH415NO3. We quantified the effect of biochar application on soil N2O emissions, as well as the fate of fertilizer-derived ammonium (NH4+) and nitrate (NO3−) in terms of their leaching from the soil, uptake into plant biomass, and recovery in the soil. We found that application of biochars reduced soil mineral N leaching and N2O emissions. Similarly, the higher biochar application rate of 5% significantly increased aboveground ryegrass biomass yield. However, no differences in N2O emissions and ryegrass biomass yields were observed between regular and nutrient-enriched biochar treatments, although mineral N leaching tended to be lower in the nutrient-enriched biochar treatment than in the regular biochar treatment. The 15N analysis revealed that biochar application increased the plant uptake of added nitrate, but reduced the plant uptake of added ammonium compared to the fertilizer only treatment. Thus, the uptake of total N derived from added NH4NO3 fertilizer was not affected by the biochar addition, and cannot explain the increase in plant biomass in biochar treatments. Instead, the increased plant biomass at the higher biochar application rate was attributed to the enhanced uptake of N derived from soil. This suggests that the interactions between biochar and native soil organic N may be important determinants of the availability of soil N to plant growth.

scholarly journals Higher stand densities can promote soil carbon storage after conversion of temperate mixed natural forests to larch plantations

2020 ◽  
Author(s):  
Meng Na ◽  
Xiaoyang Sun ◽  
Yandong Zhang ◽  
Zhihu Sun ◽  
Johannes Rousk
Keyword(s):  
Forest Management ◽  
Soil Carbon ◽  
Stand Density ◽  
C Sequestration ◽  
Tree Density ◽  
Natural Forests ◽  
Soil C ◽  
C Storage ◽  
Soil C Storage ◽  
Soil C Sequestration

AbstractSoil carbon (C) reservoirs held in forests play a significant role in the global C cycle. However, harvesting natural forests tend to lead to soil C loss, which can be countered by the establishment of plantations after clear cutting. Therefore, there is a need to determine how forest management can affect soil C sequestration. The management of stand density could provide an effective tool to control soil C sequestration, yet how stand density influences soil C remains an open question. To address this question, we investigated soil C storage in 8-year pure hybrid larch (Larix spp.) plantations with three densities (2000 trees ha−1, 3300 trees ha−1 and 4400 trees ha−1), established following the harvesting of secondary mixed natural forest. We found that soil C storage increased with higher tree density, which mainly correlated with increases of dissolved organic C as well as litter and root C input. In addition, soil respiration decreased with higher tree density during the most productive periods of warm and moist conditions. The reduced SOM decomposition suggested by lowered respiration was also corroborated with reduced levels of plant litter decomposition. The stimulated inputs and reduced exports of C from the forest floor resulted in a 40% higher soil C stock in high- compared to low-density forests within 8 years after plantation, providing effective advice for forest management to promote soil C sequestration in ecosystems.

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