scholarly journals The carbon budget of terrestrial ecosystems at country-scale – a European case study

2004 ◽  
Vol 1 (1) ◽  
pp. 167-193 ◽  
Author(s):  
I. A. Janssens ◽  
A. Freibauer ◽  
B. Schlamadinger ◽  
R. Ceulemans ◽  
P. Ciais ◽  
...  
Keyword(s):  
Carbon Balance ◽  
Management Practices ◽  
A Priori ◽  
Carbon Sources ◽  
Terrestrial Ecosystems ◽  
Carbon Fluxes ◽  
Terrestrial Carbon ◽  
Arable Soils ◽  
Carbon Balances

Abstract. We summed estimates of the carbon balance of forests, grasslands, arable lands and peatlands to obtain country-specific estimates of the terrestrial carbon balance during the 1990s. Forests and grasslands were sinking carbon consistently, whereas arable soils were carbon sources in all European countries. Hence, countries dominated by arable lands tended to be losing carbon from their terrestrial ecosystems, whereas forest-dominated countries tended to be sinking carbon. In countries where peatlands are still being drained or extracted, net carbon balances were much lower than expected from land use. Net terrestrial carbon fluxes were typically small relative to fossil fuel-related carbon emissions. Only where fossil fluxes were small and net terrestrial fluxes were large did terrestrial carbon fluxes matter (ranged between uptake of 70% of fossil fluxes and increase of emissions with 25%). Nonetheless, at the European scale, the small net balance is composed of two very large but opposing fluxes: uptake by forests and grasslands and losses from arable lands and peatlands. Thus, relatively minor changes in either or both of these large component fluxes could strongly affect the net total, indicating that mitigation schemes should not be discarded a priori. In the absence of carbon-oriented land management, the current net carbon balance is bound to decline soon. Protecting it will require actions at three levels. Firstly, maintaining the current sink activity of forests. Secondly, altered agricultural management practices to turn arable soils into carbon sinks. Lastly, because carbon is lost more rapidly than sequestered, the current large reservoirs (wetlands and old forests) need extra protection.

scholarly journals The carbon budget of terrestrial ecosystems at country-scale – a European case study

2005 ◽  
Vol 2 (1) ◽  
pp. 15-26 ◽  
Author(s):  
I. A. Janssens ◽  
A. Freibauer ◽  
B. Schlamadinger ◽  
R. Ceulemans ◽  
P. Ciais ◽  
...  
Keyword(s):  
Carbon Balance ◽  
Management Practices ◽  
A Priori ◽  
Carbon Sources ◽  
Terrestrial Ecosystems ◽  
Terrestrial Carbon ◽  
Arable Soils ◽  
Order Of Magnitude ◽  
Carbon Balances

Abstract. We summed estimates of the carbon balance of forests, grasslands, arable lands and peatlands to obtain country-specific estimates of the terrestrial carbon balance during the 1990s. Forests and grasslands were a net sink for carbon, whereas croplands were carbon sources in all European countries. Hence, countries dominated by arable lands tended to be losing carbon from their terrestrial ecosystems, whereas forest-dominated countries tended to be sequestering carbon. In some countries, draining and extraction of peatlands caused substantial reductions in the net carbon balance. Net terrestrial carbon balances were typically an order of magnitude smaller than the fossil fuel-related carbon emissions. Exceptions to this overall picture were countries where population density and industrialization are small. It is, however, of utmost importance to acknowledge that the typically small net carbon balance represents the small difference between two large but opposing fluxes: uptake by forests and grasslands and losses from arable lands and peatlands. This suggests that relatively small changes in either or both of these large component fluxes could induce large effects on the net total, indicating that mitigation schemes should not be discarded a priori. In the absence of carbon-oriented land management, the current net carbon uptake is bound to decline soon. Protecting it will require actions at three levels; a) maintaining the current sink activity of forests, b) altered agricultural management practices to reduce the emissions from arable soils or turn into carbon sinks and c) protecting current large reservoirs (wetlands and old forests), since carbon is lost more rapidly than sequestered.

scholarly journals Estimating Asian terrestrial carbon fluxes from CONTRAIL aircraft and surface CO<sub>2</sub> observations for the period 2006–2010

2014 ◽  
Vol 14 (11) ◽  
pp. 5807-5824 ◽  
Author(s):  
H. F. Zhang ◽  
B. Z. Chen ◽  
I. T. van der Laan-Luijk ◽  
T. Machida ◽  
H. Matsueda ◽  
...  
Keyword(s):  
A Priori ◽  
Carbon Fluxes ◽  
Terrestrial Carbon ◽  
Tropical Asia ◽  
Observation Network ◽  
Fossil Fuel Emission ◽  
Annual Total ◽  
Co2 Sink ◽  
Summer Flood ◽  
Ecosystem Flux

Abstract. Current estimates of the terrestrial carbon fluxes in Asia show large uncertainties particularly in the boreal and mid-latitudes and in China. In this paper, we present an updated carbon flux estimate for Asia ("Asia" refers to lands as far west as the Urals and is divided into boreal Eurasia, temperate Eurasia and tropical Asia based on TransCom regions) by introducing aircraft CO2 measurements from the CONTRAIL (Comprehensive Observation Network for Trace gases by Airline) program into an inversion modeling system based on the CarbonTracker framework. We estimated the averaged annual total Asian terrestrial land CO2 sink was about −1.56 Pg C yr−1 over the period 2006–2010, which offsets about one-third of the fossil fuel emission from Asia (+4.15 Pg C yr−1). The uncertainty of the terrestrial uptake estimate was derived from a set of sensitivity tests and ranged from −1.07 to −1.80 Pg C yr−1, comparable to the formal Gaussian error of ±1.18 Pg C yr−1 (1-sigma). The largest sink was found in forests, predominantly in coniferous forests (−0.64 ± 0.70 Pg C yr−1) and mixed forests (−0.14 ± 0.27 Pg C yr−1); and the second and third large carbon sinks were found in grass/shrub lands and croplands, accounting for −0.44 ± 0.48 Pg C yr−1 and −0.20 ± 0.48 Pg C yr−1, respectively. The carbon fluxes per ecosystem type have large a priori Gaussian uncertainties, and the reduction of uncertainty based on assimilation of sparse observations over Asia is modest (8.7–25.5%) for most individual ecosystems. The ecosystem flux adjustments follow the detailed a priori spatial patterns by design, which further increases the reliance on the a priori biosphere exchange model. The peak-to-peak amplitude of inter-annual variability (IAV) was 0.57 Pg C yr−1 ranging from −1.71 Pg C yr−1 to −2.28 Pg C yr−1. The IAV analysis reveals that the Asian CO2 sink was sensitive to climate variations, with the lowest uptake in 2010 concurrent with a summer flood and autumn drought and the largest CO2 sink in 2009 owing to favorable temperature and plentiful precipitation conditions. We also found the inclusion of the CONTRAIL data in the inversion modeling system reduced the uncertainty by 11% over the whole Asian region, with a large reduction in the southeast of boreal Eurasia, southeast of temperate Eurasia and most tropical Asian areas.

Exploring the effects of biodiversity and elemental stoichiometry on terrestrial carbon balance

2020 ◽  
Author(s):  
Marcos Fernández-Martínez ◽  
Jordi Sardans ◽  
Josep Peñuelas ◽  
Ivan Janssens
Keyword(s):  
Global Change ◽  
Elemental Composition ◽  
Carbon Balance ◽  
Terrestrial Ecosystems ◽  
Terrestrial Carbon ◽  
Endogenous Factors ◽  
Ecosystem Carbon ◽  
Elemental Stoichiometry ◽  
Ecosystem Carbon Balance

&lt;p&gt;Global change is affecting the capacity of terrestrial ecosystems to sequester carbon. While the effect of climate on ecosystem carbon balance has largely been explored, the role of other potentially important factors that may shift with global change, such as biodiversity and the concentration of nutrients remains elusive. More diverse ecosystems have been shown to be more productive and stable over time and differences in foliar concentrations of N and P are related to large differences in how primary producers function. Here, we used 89 eddy-covariance sites included in the FLUXNET 2015 database, from which we compiled information on climate, species abundance and elemental composition of the main species. With these data, we assessed the relative importance of climate, endogenous factors, biodiversity and community-weighted concentrations of foliar N and P on terrestrial carbon balance. Climate and endogenous factors, such as stand age, are the main determinants of terrestrial C balance and their interannual variability in all types of ecosystems. Elemental stoichiometry, though, played a significant role affecting photosynthesis, an effect that propagates through ecosystem respiration and carbon sequestration. Biodiversity, instead, had a very limited effect on terrestrial carbon balance. We found increased respiration rates and more stable gross primary production with increasing diversity. Our results are the first attempt to investigate the role of biodiversity and the elemental composition of terrestrial ecosystems in ecosystem carbon balance.&lt;/p&gt;

scholarly journals Aquatic carbon cycling in the conterminous United States and implications for terrestrial carbon accounting

2015 ◽  
Vol 113 (1) ◽  
pp. 58-63 ◽  
Author(s):  
David Butman ◽  
Sarah Stackpoole ◽  
Edward Stets ◽  
Cory P. McDonald ◽  
David W. Clow ◽  
...  
Keyword(s):  
United States ◽  
Carbon Flux ◽  
Carbon Sources ◽  
Terrestrial Ecosystems ◽  
Carbon Fluxes ◽  
Carbon Accounting ◽  
Modeling Framework ◽  
Carbon Mass ◽  
Lakes And Reservoirs ◽  
Water Ecosystems

Inland water ecosystems dynamically process, transport, and sequester carbon. However, the transport of carbon through aquatic environments has not been quantitatively integrated in the context of terrestrial ecosystems. Here, we present the first integrated assessment, to our knowledge, of freshwater carbon fluxes for the conterminous United States, where 106 (range: 71–149) teragrams of carbon per year (TgC⋅y−1) is exported downstream or emitted to the atmosphere and sedimentation stores 21 (range: 9–65) TgC⋅y−1in lakes and reservoirs. We show that there is significant regional variation in aquatic carbon flux, but verify that emission across stream and river surfaces represents the dominant flux at 69 (range: 36–110) TgC⋅y−1or 65% of the total aquatic carbon flux for the conterminous United States. Comparing our results with the output of a suite of terrestrial biosphere models (TBMs), we suggest that within the current modeling framework, calculations of net ecosystem production (NEP) defined as terrestrial only may be overestimated by as much as 27%. However, the internal production and mineralization of carbon in freshwaters remain to be quantified and would reduce the effect of including aquatic carbon fluxes within calculations of terrestrial NEP. Reconciliation of carbon mass–flux interactions between terrestrial and aquatic carbon sources and sinks will require significant additional research and modeling capacity.

scholarly journals Climate data induced uncertainties in simulated carbon fluxes under corn and soybean systems

2020 ◽  
Author(s):  
Varaprasad Bandaru
Keyword(s):  
Carbon Flux ◽  
Carbon Balance ◽  
Management Practices ◽  
Irrigation Management ◽  
Carbon Fluxes ◽  
Climate Data ◽  
Weather Variables ◽  
Relative Significance ◽  
Daily Weather ◽  
The U.S

Abstract. Net carbon balance on croplands depends on numerous factors (e.g., crop type, soil, climate and management practices) and their interactions. Agroecosystem models are generally used to assess cropland carbon fluxes under various agricultural land use and land management practices because of their ability to capture the complex interactive effects of factors influencing carbon balance. For regional carbon flux simulations, generally gridded climate data sets are used because they offer data for each grid cell of the region of interest. However, studies consistently report large uncertainties in gridded climate datasets, which will affect the accuracy of carbon flux simulations. This study investigates the uncertainties in daily weather variables of commonly used high resolution gridded climate datasets in the U.S (NARR, NLDAS, Prism and Daymet), and their impact on the accuracy of simulated Net Ecosystem Exchange (NEE) under irrigated and non-irrigated corn and soybeans using the Environmental Policy Integrated Climate (EPIC) agroecosystem model and observational data at four flux tower cropland sites in the U.S Midwest region. Further, the relative significance of each weather variable in influencing the uncertainty in flux estimates was evaluated. Results suggest that daily weather variables in all gridded climate datasets display some degree of bias, leading to considerable uncertainty in simulated NEE fluxes. The gridded climate datasets produced based on interpolation techniques (i.e. Daymet and Prism) were shown to have less uncertainties, and resulted in NEE estimates with relatively higher accuracy, likely due to their higher spatial resolution and higher dependency on meteorological station observations. The Mean Absolute Percentage Errors (MAPE) values of average growing season NEE estimates for Dayment, Prism, NLDAS and NARR include 22.53 %, 23.45 %, 62.52 % and 66.18 %, respectively. The NEE under irrigation management (MAPE = 53.15 %) tends to be more sensitive to uncertainties compared to the fluxes under non-irrigation (MAPE = 34.19 %). Further, this study highlights that NEE fluxes respond differently to the individual climate variables, and responses vary with management practices. Under irrigation management, NEE fluxes are more sensitive to shortwave radiation and temperature. Conversely, under non-irrigation management, precipitation is the most dominant climate factor influencing uncertainty in simulated NEE fluxes. These findings demonstrate that careful consideration is necessary when selecting climate data to mitigate uncertainties in simulated NEE fluxes. Further, alternative approaches such as integration of remote sensing data products may help reduce the models' dependency on climate datasets and improve the accuracy in the simulated CO2 fluxes.

Land Use Structure Optimization Based on Carbon Balance：A Case Study in Lanzhou of Gansu Province

2012 ◽  
Vol 518-523 ◽  
pp. 6069-6074 ◽  
Author(s):  
Hai Meng Liu ◽  
Pei Ji Shi ◽  
Ming Hui Sun
Keyword(s):  
Land Use ◽  
Carbon Emissions ◽  
Land Use Planning ◽  
Carbon Balance ◽  
Carbon Sink ◽  
Terrestrial Ecosystems ◽  
Optimization Scheme ◽  
Land Use Structure ◽  
Land Use Structure Optimization

Land use structure optimization is the core of land use planning, which has significant influence to the carbon cycle in terrestrial ecosystems. In this paper, we put Lanzhou as case study, to realize the land ecosystem carbon balance is the breakthrough point, using the method of fuzzy linear programming, constructing model from carbon source and carbon sink, trying to put forward a new approach to optimize the land use structure. Contrast with the former planning with the optimization scheme based on carbon balance, carbon stock volume and carbon emissions of the year 2005 and 2020 are evaluated .We got a low carbon optimization scheme of land use planning finally. The results of the study show that the objective to make carbon storage maximization and to make carbon emissions minimization is consistent and the two optimizing schemes have dramatically beneficial effect on increase carbon sink and reduce carbon source, which can slow down carbon emissions in terrestrial ecosystems and realize the rational utilization of land resources and the sustainable development.

scholarly journals Young, Old, and Weathered Carbon-Part 1: Using Radiocarbon and Stable Isotopes to Identify Carbon Sources in an Alkaline, Humic Lake

Radiocarbon ◽  
2015 ◽  
Vol 57 (3) ◽  
pp. 407-423 ◽  
Author(s):  
Evelyn M Keaveney ◽  
Paula J Reimer ◽  
Robert H Foy
Keyword(s):  
Organic Carbon ◽  
Inorganic Carbon ◽  
Dissolved Inorganic Carbon ◽  
Carbon Sources ◽  
Terrestrial Carbon ◽  
Different Sources ◽  
Global Carbon ◽  
Young Old

This article presents a case study of Lower Lough Erne, a humic, alkaline lake in northwest Ireland, and uses the radiocarbon method to determine the source and age of carbon to establish whether terrestrial carbon is utilized by heterotrophic organisms or buried in sediment. Stepped combustion was used to estimate the degree of the burial of terrestrial carbon in surface sediment. Δ14C, δ13C, and δ15N values were measured for phytoplankton, dissolved inorganic carbon (DIC), dissolved organic carbon (DOC), and particulate organic carbon (POC). Δ14C values were used to indicate the presence of different sources of carbon, including bedrock-derived inorganic carbon, “modern,” “recent,” “subsurface,” and “subfossil” terrestrial carbon in the lake. The use of 14C in conjunction with novel methods (e.g. stepped combustion) allows the determination of the pathway of terrestrial carbon in the system, which has implications for regional and global carbon cycling.

scholarly journals Biological control of the terrestrial carbon sink

2006 ◽  
Vol 3 (2) ◽  
pp. 147-166 ◽  
Author(s):  
E.-D. Schulze
Keyword(s):  
Stomatal Conductance ◽  
Carbon Balance ◽  
Microbial Respiration ◽  
Carbon Sink ◽  
Carbon Fluxes ◽  
Carbon Gain ◽  
Limiting Factor ◽  
Terrestrial Carbon ◽  
The Future ◽  
Main Factor

Abstract. This lecture reviews the past (since 1964 when the International Biological Program began) and the future of our understanding of terrestrial carbon fluxes with focus on photosynthesis, respiration, primary-, ecosystem-, and biome-productivity. Photosynthetic capacity is related to the nitrogen concentration of leaves, but the capacity is only rarely reached under field conditions. Average rates of photosynthesis and stomatal conductance are closely correlated and operate near 50% of their maximal rate, with light being the limiting factor in humid regions and air humidity and soil water the limiting factor in arid climates. Leaf area is the main factor to extrapolate from leaves to canopies, with maximum surface conductance being dependent on leaf level stomatal conductance. Additionally, gas exchange depends also on rooting depth which determines the water and nutrient availability and on mycorrhizae which regulate the nutrient status. An important anthropogenic disturbance is the nitrogen uptake from air pollutants, which is not balanced by cation uptake from roots and this may lead to damage and breakdown of the plant cover. Photosynthesis is the main carbon input into ecosystems, but it alone does not represent the ecosystem carbon balance, which is determined by respiration of various kinds. Plant respiration and photosynthesis determine growth (net primary production) and microbial respiration balances the net ecosystem flux. In a spruce forest, 30% of the assimilatory carbon gain is used for respiration of needles, 20% is used for respiration in stems. Soil respiration is about 50% the carbon gain, half of which is root respiration, half is microbial respiration. In addition, disturbances lead to carbon losses, where fire, harvest and grazing bypass the chain of respiration. In total, the carbon balance at the biome level is only about 1% of the photosynthetic carbon input, or may indeed become negative. The recent observed increase in plant growth has different reasons depending on the region of the world: anthropogenic nitrogen deposition is the controlling factor in Europe, increasing global temperatures is the main factor in Siberia, and maybe rising CO2 the factor controlling the carbon fluxes in Amazonia. However, this has not lead to increases in net biome productivity, due to associated losses. Also important is the interaction between biodiversity and biogeochemical processes. It is shown that net primary productivity increases with plant species diversity (50% species loss equals 20% loss in productivity). However, in this extrapolation the action of soil biota is poorly understood although soils contribute the largest number of species and of taxonomic groups to an ecosystem. The global terrestrial carbon budget strongly depends on areas with pristine old growth forests which are carbon sinks. The management options are very limited, mostly short term, and usually associated with high uncertainty. Unmanaged grasslands appear to be a carbon sink of similar magnitude as forest, but generally these ecosystems lost their C with grazing and agricultural use. Extrapolation to the future of Earth climate shows that the biota will not be able to balance fossil fuel emissions, and that it will be essential to develop a carbon free energy system in order to maintain the living conditions on earth.

scholarly journals The carbon budget of terrestrial ecosystems in East Asia over the last two decades

2012 ◽  
Vol 9 (9) ◽  
pp. 3571-3586 ◽  
Author(s):  
S. L. Piao ◽  
A. Ito ◽  
S. G. Li ◽  
Y. Huang ◽  
P. Ciais ◽  
...  
Keyword(s):  
Climate Change ◽  
Carbon Cycle ◽  
East Asia ◽  
Carbon Storage ◽  
Carbon Balance ◽  
Carbon Sink ◽  
Regional Scale ◽  
Terrestrial Ecosystems ◽  
Carbon Accumulation ◽  
Terrestrial Carbon

Abstract. This REgional Carbon Cycle Assessment and Processes regional study provides a synthesis of the carbon balance of terrestrial ecosystems in East Asia, a region comprised of China, Japan, North and South Korea, and Mongolia. We estimate the current terrestrial carbon balance of East Asia and its driving mechanisms during 1990–2009 using three different approaches: inventories combined with satellite greenness measurements, terrestrial ecosystem carbon cycle models and atmospheric inversion models. The magnitudes of East Asia's terrestrial carbon sink from these three approaches are comparable: −0.293±0.033 PgC yr−1 from inventory–remote sensing model–data fusion approach, −0.413±0.141 PgC yr−1 (not considering biofuel emissions) or −0.224±0.141 PgC yr−1 (considering biofuel emissions) for carbon cycle models, and −0.270±0.507 PgC yr−1 for atmospheric inverse models. Here and in the following, the numbers behind ± signs are standard deviations. The ensemble of ecosystem modeling based analyses further suggests that at the regional scale, climate change and rising atmospheric CO2 together resulted in a carbon sink of −0.289±0.135 PgC yr−1, while land-use change and nitrogen deposition had a contribution of −0.013±0.029 PgC yr−1 and −0.107±0.025 PgC yr−1, respectively. Although the magnitude of climate change effects on the carbon balance varies among different models, all models agree that in response to climate change alone, southern China experienced an increase in carbon storage from 1990 to 2009, while northern East Asia including Mongolia and north China showed a decrease in carbon storage. Overall, our results suggest that about 13–27% of East Asia's CO2 emissions from fossil fuel burning have been offset by carbon accumulation in its terrestrial territory over the period from 1990 to 2009. The underlying mechanisms of carbon sink over East Asia still remain largely uncertain, given the diversity and intensity of land management processes, and the regional conjunction of many drivers such as nutrient deposition, climate, atmospheric pollution and CO2 changes, which cannot be considered as independent for their effects on carbon storage.

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