scholarly journals Nitrogen feedbacks increase future terrestrial ecosystem carbon uptake in an individual-based dynamic vegetation model

2014 ◽  
Vol 11 (1) ◽  
pp. 151-185 ◽  
Author(s):  
D. Wårlind ◽  
B. Smith ◽  
T. Hickler ◽  
A. Arneth
Keyword(s):  
Carbon Sequestration ◽  
Nitrogen Cycle ◽  
Environmental Changes ◽  
Nitrogen Dynamics ◽  
Carbon Uptake ◽  
Terrestrial Carbon ◽  
Vegetation Model ◽  
Carbon And Nitrogen ◽  
Dynamic Vegetation Model ◽  
Ecosystem Carbon

Abstract. Recently a considerable amount of effort has been put into quantifying how interactions of the carbon and nitrogen cycle affect future terrestrial carbon sinks. Dynamic vegetation models, representing the nitrogen cycle with varying degree of complexity, have shown diverging constraints of nitrogen dynamics on future carbon sequestration. In this study, we use the dynamic vegetation model LPJ-GUESS to evaluate how population dynamics and resource competition between plant functional types, combined with nitrogen dynamics, have influenced the terrestrial carbon storage in the past and to investigate how terrestrial carbon and nitrogen dynamics might change in the future (1850 to 2100; one exemplary "business-as-usual" climate scenario). Single factor model experiments of CO2 fertilisation and climate change show generally similar directions of the responses of C–N interactions, compared to the C-only version of the model, as documented in previous studies. Under a RCP 8.5 scenario, nitrogen limitation suppresses potential CO2 fertilisation, reducing the cumulative net ecosystem carbon uptake between 1850 and 2100 by 61%, and soil warming-induced increase in nitrogen mineralisation reduces terrestrial carbon loss by 31%. When environmental changes are considered conjointly, carbon sequestration is limited by nitrogen dynamics until present. However, during the 21st century nitrogen dynamics induce a net increase in carbon sequestration, resulting in an overall larger carbon uptake of 17% over the full period. This contradicts earlier model results that showed an 8 to 37% decrease in carbon uptake, questioning the often stated assumption that projections of future terrestrial C dynamics from C-only models are too optimistic.

scholarly journals Nitrogen feedbacks increase future terrestrial ecosystem carbon uptake in an individual-based dynamic vegetation model

2014 ◽  
Vol 11 (21) ◽  
pp. 6131-6146 ◽  
Author(s):  
D. Wårlind ◽  
B. Smith ◽  
T. Hickler ◽  
A. Arneth
Keyword(s):  
Carbon Sequestration ◽  
Nitrogen Cycle ◽  
Nitrogen Dynamics ◽  
Carbon Uptake ◽  
Terrestrial Carbon ◽  
Vegetation Model ◽  
Global Models ◽  
Carbon And Nitrogen ◽  
Dynamic Vegetation Model ◽  
Ecosystem Carbon

Abstract. Recently a considerable amount of effort has been put into quantifying how interactions of the carbon and nitrogen cycle affect future terrestrial carbon sinks. Dynamic vegetation models, representing the nitrogen cycle with varying degree of complexity, have shown diverging constraints of nitrogen dynamics on future carbon sequestration. In this study, we use LPJ-GUESS, a dynamic vegetation model employing a detailed individual- and patch-based representation of vegetation dynamics, to evaluate how population dynamics and resource competition between plant functional types, combined with nitrogen dynamics, have influenced the terrestrial carbon storage in the past and to investigate how terrestrial carbon and nitrogen dynamics might change in the future (1850 to 2100; one representative "business-as-usual" climate scenario). Single-factor model experiments of CO2 fertilisation and climate change show generally similar directions of the responses of C–N interactions, compared to the C-only version of the model as documented in previous studies using other global models. Under an RCP 8.5 scenario, nitrogen limitation suppresses potential CO2 fertilisation, reducing the cumulative net ecosystem carbon uptake between 1850 and 2100 by 61%, and soil warming-induced increase in nitrogen mineralisation reduces terrestrial carbon loss by 31%. When environmental changes are considered conjointly, carbon sequestration is limited by nitrogen dynamics up to the present. However, during the 21st century, nitrogen dynamics induce a net increase in carbon sequestration, resulting in an overall larger carbon uptake of 17% over the full period. This contrasts with previous results with other global models that have shown an 8 to 37% decrease in carbon uptake relative to modern baseline conditions. Implications for the plausibility of earlier projections of future terrestrial C dynamics based on C-only models are discussed.

scholarly journals Consequences of Considering Carbon–Nitrogen Interactions on the Feedbacks between Climate and the Terrestrial Carbon Cycle

2008 ◽  
Vol 21 (15) ◽  
pp. 3776-3796 ◽  
Author(s):  
Andrei P. Sokolov ◽  
David W. Kicklighter ◽  
Jerry M. Melillo ◽  
Benjamin S. Felzer ◽  
C. Adam Schlosser ◽  
...  
Keyword(s):  
Carbon Sequestration ◽  
Carbon Cycle ◽  
Carbon Emissions ◽  
Terrestrial Ecosystems ◽  
Co2 Concentration ◽  
Nitrogen Dynamics ◽  
Carbon Uptake ◽  
Terrestrial Carbon ◽  
Surface Warming ◽  
Terrestrial Carbon Cycle

Abstract The impact of carbon–nitrogen dynamics in terrestrial ecosystems on the interaction between the carbon cycle and climate is studied using an earth system model of intermediate complexity, the MIT Integrated Global Systems Model (IGSM). Numerical simulations were carried out with two versions of the IGSM’s Terrestrial Ecosystems Model, one with and one without carbon–nitrogen dynamics. Simulations show that consideration of carbon–nitrogen interactions not only limits the effect of CO2 fertilization but also changes the sign of the feedback between the climate and terrestrial carbon cycle. In the absence of carbon–nitrogen interactions, surface warming significantly reduces carbon sequestration in both vegetation and soil by increasing respiration and decomposition (a positive feedback). If plant carbon uptake, however, is assumed to be nitrogen limited, an increase in decomposition leads to an increase in nitrogen availability stimulating plant growth. The resulting increase in carbon uptake by vegetation exceeds carbon loss from the soil, leading to enhanced carbon sequestration (a negative feedback). Under very strong surface warming, however, terrestrial ecosystems become a carbon source whether or not carbon–nitrogen interactions are considered. Overall, for small or moderate increases in surface temperatures, consideration of carbon–nitrogen interactions result in a larger increase in atmospheric CO2 concentration in the simulations with prescribed carbon emissions. This suggests that models that ignore terrestrial carbon–nitrogen dynamics will underestimate reductions in carbon emissions required to achieve atmospheric CO2 stabilization at a given level. At the same time, compensation between climate-related changes in the terrestrial and oceanic carbon uptakes significantly reduces uncertainty in projected CO2 concentration.

scholarly journals Legacy effects from historical environmental changes dominate future terrestrial carbon uptake

2020 ◽  
Author(s):  
Andreas Krause ◽  
Almut Arneth ◽  
Anja Rammig
Keyword(s):  
Climate Change ◽  
Carbon Cycling ◽  
Environmental Changes ◽  
Carbon Accumulation ◽  
Environmental Drivers ◽  
Carbon Uptake ◽  
Legacy Effects ◽  
Terrestrial Carbon ◽  
Dynamic Global Vegetation Model ◽  
Wood Harvest

<p>The carbon balance of terrestrial ecosystems is determined by environmental drivers (chiefly related to climate and land use) which interact with each other and change over time. In particular, ecosystems are presently still affected by past environmental changes because they have not yet reached equilibrium with their environment. However, the magnitude and drivers of this legacy effect for the upcoming decades are still unclear. Here, we use the dynamic global vegetation model LPJ-GUESS to calculate the effects of historical (1850-2015) and future (2015-2099, exemplarily for the high emission/moderate deforestation scenario SSP5-8.5) environmental changes on historical and future terrestrial carbon cycling and to quantify the contributions of the following environmental drivers: climate change, CO<sub>2 </sub>fertilization, agricultural expansion, shifting cultivation frequency, wood harvest, nitrogen deposition, and nitrogen fertilization.</p><p>According to our simulations, the land represented a cumulative net carbon source (-154 GtC) over the historical period mainly due to deforestation, wood harvest, and negative climate change impacts partly offset by carbon uptake via increased CO<sub>2</sub> levels and nitrogen input. In contrast, the land is simulated to act as a net carbon sink (+118 GtC) over the 21<sup>st</sup> century. This is mostly a result of historical environmental changes as ecosystems still adapt to present-day CO<sub>2</sub> and nitrogen availability as well as long-term vegetation regrowth following agricultural abandonment and wood harvest. The net impact of future environmental changes on future carbon cycling is much smaller because effects from individual environmental drivers largely compensate. Historical environmental changes dominate future terrestrial carbon cycling at least until mid-century when legacy effects gradually diminish and future environmental changes start to trigger carbon accumulation. Our results suggest that legacy effects persist even many decades after environmental changes occurred and need to be considered when interpreting alterations of the terrestrial carbon cycle.</p>

scholarly journals Analysis of carbon sequestration sensitivity to recent changes in land use patterns over Belgium using a combination of models and remote sensing techniques

2020 ◽  
Author(s):  
Arpita Verma ◽  
Ingrid Jacquemin ◽  
Louis Francois ◽  
Nicolas Dendoncker ◽  
Veronique Beckers ◽  
...  
Keyword(s):  
Land Use ◽  
Driving Forces ◽  
Carbon Sink ◽  
Carbon Stocks ◽  
Spatial And Temporal Variability ◽  
Terrestrial Carbon ◽  
Vegetation Model ◽  
Land Use Patterns ◽  
Dynamic Vegetation Model ◽  
The Impact

<p>Changes in land use/land cover (LU/LC) practices are critical to determine and this is one of the crucial driving forces of terrestrial ecosystem productivity and carbon sink variability. However, relatively few studies have quantified the impact of LU/LC change on the terrestrial carbon cycle. In the present study, we developed a workflow for quantifying and assessing changes in terrestrial carbon stocks due to land use change using a dynamic vegetation model. The main objectives are to assess status and variation in carbon stocks across land covers, towards the quantification of spatial distribution and dynamic variation of terrestrial carbon sinks in response to LU/LC change. Here, with the CARAIB dynamic vegetation model, we perform simulations using several sets of LU/LC data to analyse the sensitivity of the carbon sink. We propose a new method of using satellite – and machine learning-based observation to reconstruct historical LU/LC change and compare it with static data from the cadastral map and dynamic data from an agent-based model coupled with CARAIB. It will quantify the spatial and temporal variability of land use during the 2000-2019 period over Belgium at high resolution. This study will give the space to analyse past information and hence calibrate the dynamic vegetation model to minimize uncertainty in the future projection (until 2035). Overall, this study allows us to understand the effect of changing land use pattern and identify the input dataset which minimizes the uncertainty in model estimation.</p>

scholarly journals Effect of increased temperature on carbon and nitrogen uptake of two intertidal foraminifera (<i>Ammonia tepida</i> and <i>Haynesina germanica</i>)

2016 ◽  
Author(s):  
Julia Wukovits ◽  
Annekatrin J. Enge ◽  
Wolfgang Wanek ◽  
Margarete Watzka ◽  
Petra Heinz
Keyword(s):  
Nitrogen Uptake ◽  
Food Source ◽  
Environmental Changes ◽  
Potential Temperature ◽  
Carbon Uptake ◽  
Nutrient Fluxes ◽  
Carbon And Nitrogen ◽  
Foraminiferal Species ◽  
Freeze Dried ◽  
Uptake Rates

Abstract. Benthic foraminifera are highly abundant heterotrophic protists in marine sediments, but intertidal communities are expected to undergo future changes. Environmental changes can exceed the tolerance limits of intertidal species causing a shift in species composition which might result in altered nutrient fluxes. Factors limiting the abundance of specific foraminiferal species can be temperature related stress tolerance or food source processing efficiency. In this study, we performed a laboratory feeding experiment on Ammonia tepida and Haynesina germanica, two dominant foraminiferal species of the German Wadden Sea/Friedrichskoog, to test the effect of temperature on phytodetritus ingestion. The specimens were fed with 13C and 15N labelled freeze dried Dunaliella tertiolecta (green algae) at the start of the experiment and were incubated at 20 °C, 25 °C, and 30 °C respectively. Dual labelling was applied to observe potential temperature effects on the relation of phytodetrital carbon and nitrogen retention. Samples were taken over a period of two weeks. Foraminiferal cytoplasm was isotopically analysed to investigate differences in carbon and nitrogen uptake derived from the food source. Both species showed a positive response to the provided food source, but carbon uptake rates of A. tepida were 10-fold higher compared to those of H. germanica. Increased temperatures had a far stronger impact on carbon uptake of H. germanica than on A. tepida. A distinct increase in levels of phytodetrital derived nitrogen (compared to more steady carbon levels) could be observed over the course of the experiment. The results suggest that higher temperatures have a significant negative effect on the carbon exploitation of H. germanica. For A. tepida, higher carbon uptake rates and the enhanced tolerance range for higher temperatures could outline an advantage in warmer periods, if the main food source consists of chlorophyte phytodetritus. These conditions are likely to impact nutrient fluxes in A. tepida/H. germanica associations.

scholarly journals Legacy Effects from Historical Environmental Changes Dominate Future Terrestrial Carbon Uptake

2020 ◽  
Vol 8 (10) ◽  
Author(s):  
A. Krause ◽  
A. Arneth ◽  
P. Anthoni ◽  
A. Rammig
Keyword(s):  
Environmental Changes ◽  
Carbon Uptake ◽  
Legacy Effects ◽  
Terrestrial Carbon

scholarly journals Contributions of secondary forest and nitrogen dynamics to terrestrial carbon uptake

2010 ◽  
Vol 7 (2) ◽  
pp. 2739-2765 ◽  
Author(s):  
X. Yang ◽  
T. K. Richardson ◽  
A. K. Jain
Keyword(s):  
Land Use ◽  
Land Use Change ◽  
Secondary Forest ◽  
Nitrogen Dynamics ◽  
Carbon Uptake ◽  
Secondary Forests ◽  
Terrestrial Carbon ◽  
Tropical Regions ◽  
Forest Regrowth ◽  
Limiting Nutrient

Abstract. We use a terrestrial carbon-nitrogen cycle component of the Integrated Science Assessment Model (ISAM) to investigate the impacts of nitrogen dynamics on regrowing secondary forests over the 20th century. We further examine what the impacts of nitrogen deposition and land use change history are on terrestrial carbon uptake since preindustrial time. Our results suggest that global total net land use emissions for the 1990s associated with changes in cropland, pastureland, and wood harvest are 1.22 GtC/yr. Without considering the secondary forest regrowth, the estimated net global total land use emissions are 1.58 GtC/yr or about 0.36 GtC/yr higher than if secondary forest regrowth is considered. Results also show that without considering the nitrogen dynamics and deposition, the estimated global total secondary forest sink for the 1990s is 0.90 GtC/yr or about 0.54 GtC/yr higher than estimates that include the impacts of nitrogen dynamics and deposition. Nitrogen deposition alone is responsible for about 0.13 GtC/yr of the total secondary forest sink. While nitrogen is not a limiting nutrient in the intact primary forests in tropical regions, our study suggests that nitrogen becomes a limiting nutrient for regrowing secondary forests of the tropical regions, in particular Latin America and Tropical Africa. This is because land use change activities, especially wood harvest, removes large amounts of nitrogen from the system when slash is burnt or wood is removed for harvest. However, our model results show that carbon uptake is enhanced in the tropical secondary forests of the Indian region. We argue that this may be due to enhanced nitrogen mineralization and increased nitrogen availability following land use change in the Indian tropical forest ecosystems. Results also demonstrate that there is a significant amount of carbon accumulating in the Northern Hemisphere where most land use changes and forest regrowth has occurred in recent decades. This study indicates the significance of secondary forests to terrestrial carbon sinks, the importance of nitrogen dynamics to the magnitude of secondary forests carbon uptake, and therefore the need to include both primary and secondary forests and nitrogen dynamics in terrestrial ecosystem models.

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