scholarly journals Recent Changes in Global Photosynthesis and Terrestrial Ecosystem Respiration Constrained From Multiple Observations

2018 ◽  
Vol 45 (2) ◽  
pp. 1058-1068 ◽  
Author(s):  
Wei Li ◽  
Philippe Ciais ◽  
Yilong Wang ◽  
Yi Yin ◽  
Shushi Peng ◽  
...  
Keyword(s):  
Ecosystem Respiration ◽  
Terrestrial Ecosystem ◽  
Multiple Observations

scholarly journals A temperature threshold to identify the driving climate forces of the respiratory process in terrestrial ecosystems

2017 ◽  
Author(s):  
Zhiyuan Zhang ◽  
Renduo Zhang ◽  
Yang Zhou ◽  
Alessandro Cescatti ◽  
Georg Wohlfahrt ◽  
...  
Keyword(s):  
Air Temperature ◽  
Driving Forces ◽  
Ecosystem Respiration ◽  
Large Fraction ◽  
Terrestrial Ecosystem ◽  
Terrestrial Ecosystems ◽  
Co2 Concentration ◽  
Temperature Threshold ◽  
Current Scenario ◽  
Ecosystem Flux

Abstract. Terrestrial ecosystem respiration (Re) is the major source of CO2 release and constitutes the second largest carbon flux between the biosphere and atmosphere. Therefore, climate-driven changes of Re may greatly impact on future atmospheric CO2 concentration. The aim of this study was to derive an air temperature threshold for identifying the driving climate forces of the respiratory process in terrestrial ecosystems within different temperature zones. For this purpose, a global dataset of 647 site-years of ecosystem flux data collected at 152 sites has been examined. Our analysis revealed an ecosystem threshold of mean annual air temperature (MAT) of 11 ± 2.3 °C. In ecosystems with the MAT below this threshold, the maximum Re rates were primarily dependent on temperature and respiration was mainly a temperature-driven process. On the contrary, in ecosystems with the MAT greater than 11 ± 2.3 °C, in addition to temperature, other driving forces, such as water availability and surface heat flux, became significant drivers of the maximum Re rates and respiration was a multi-factor-driven process. The information derived from this study highlight the key role of temperature as main controlling factor of the maximum Re rates on a large fraction of the terrestrial biosphere, while other driving forces reduce the maximum Re rates and temperature sensitivity of the respiratory process. These findings are particularly relevant under the current scenario of rapid global warming, given that the potential climate-induced changes in ecosystem respiration may lead to substantial anomalies in the seasonality and magnitude of the terrestrial carbon budget.

scholarly journals Towards a standardized processing of Net Ecosystem Exchange measured with eddy covariance technique: algorithms and uncertainty estimation

2006 ◽  
Vol 3 (4) ◽  
pp. 571-583 ◽  
Author(s):  
D. Papale ◽  
M. Reichstein ◽  
M. Aubinet ◽  
E. Canfora ◽  
C. Bernhofer ◽  
...  
Keyword(s):  
Eddy Covariance ◽  
Ecosystem Respiration ◽  
Gross Primary Production ◽  
Net Ecosystem Exchange ◽  
Terrestrial Ecosystem ◽  
Climatic Conditions ◽  
High Temporal Resolution ◽  
Eddy Covariance Technique ◽  
Forest Sites ◽  
European Database

Abstract. Eddy covariance technique to measure CO2, water and energy fluxes between biosphere and atmosphere is widely spread and used in various regional networks. Currently more than 250 eddy covariance sites are active around the world measuring carbon exchange at high temporal resolution for different biomes and climatic conditions. In this paper a new standardized set of corrections is introduced and the uncertainties associated with these corrections are assessed for eight different forest sites in Europe with a total of 12 yearly datasets. The uncertainties introduced on the two components GPP (Gross Primary Production) and TER (Terrestrial Ecosystem Respiration) are also discussed and a quantitative analysis presented. Through a factorial analysis we find that generally, uncertainties by different corrections are additive without interactions and that the heuristic u*-correction introduces the largest uncertainty. The results show that a standardized data processing is needed for an effective comparison across biomes and for underpinning inter-annual variability. The methodology presented in this paper has also been integrated in the European database of the eddy covariance measurements.

scholarly journals McGill wetland model: evaluation of a peatland carbon simulator developed for global assessments

2010 ◽  
Vol 7 (11) ◽  
pp. 3517-3530 ◽  
Author(s):  
F. St-Hilaire ◽  
J. Wu ◽  
N. T. Roulet ◽  
S. Frolking ◽  
P. M. Lafleur ◽  
...  
Keyword(s):  
Water Table ◽  
Ecosystem Respiration ◽  
Gross Primary Production ◽  
General Structure ◽  
Terrestrial Ecosystem ◽  
Ecosystem Model ◽  
Terrestrial Ecosystem Model ◽  
Use Efficiency ◽  
One Year ◽  
Anoxic Zones

Abstract. We developed the McGill Wetland Model (MWM) based on the general structure of the Peatland Carbon Simulator (PCARS) and the Canadian Terrestrial Ecosystem Model. Three major changes were made to PCARS: (1) the light use efficiency model of photosynthesis was replaced with a biogeochemical description of photosynthesis; (2) the description of autotrophic respiration was changed to be consistent with the formulation of photosynthesis; and (3) the cohort, multilayer soil respiration model was changed to a simple one box peat decomposition model divided into an oxic and anoxic zones by an effective water table, and a one-year residence time litter pool. MWM was then evaluated by comparing its output to the estimates of net ecosystem production (NEP), gross primary production (GPP) and ecosystem respiration (ER) from 8 years of continuous measurements at the Mer Bleue peatland, a raised ombrotrophic bog located in southern Ontario, Canada (index of agreement [dimensionless]: NEP = 0.80, GPP = 0.97, ER = 0.97; systematic RMSE [g C m−2 d−1]: NEP = 0.12, GPP = 0.07, ER = 0.14; unsystematic RMSE: NEP = 0.15, GPP = 0.27, ER = 0.23). Simulated moss NPP approximates what would be expected for a bog peatland, but shrub NPP appears to be underestimated. Sensitivity analysis revealed that the model output did not change greatly due to variations in water table because of offsetting responses in production and respiration, but that even a modest temperature increase could lead to converting the bog from a sink to a source of CO2. General weaknesses and further developments of MWM are discussed.

scholarly journals Divergent apparent temperature sensitivity of terrestrial ecosystem respiration

2014 ◽  
Vol 7 (5) ◽  
pp. 419-428 ◽  
Author(s):  
Bing Song ◽  
Shuli Niu ◽  
Ruisen Luo ◽  
Yiqi Luo ◽  
Jiquan Chen ◽  
...  
Keyword(s):  
Temperature Sensitivity ◽  
Ecosystem Respiration ◽  
Terrestrial Ecosystem ◽  
Apparent Temperature

scholarly journals Constraining a global ecosystem model with multi-site eddy-covariance data

2012 ◽  
Vol 9 (10) ◽  
pp. 3757-3776 ◽  
Author(s):  
S. Kuppel ◽  
P. Peylin ◽  
F. Chevallier ◽  
C. Bacour ◽  
F. Maignan ◽  
...  
Keyword(s):  
Eddy Covariance ◽  
Vegetation Index ◽  
Ecosystem Respiration ◽  
Terrestrial Ecosystem ◽  
Co2 Flux ◽  
Parameter Analysis ◽  
Single Site ◽  
Biogeochemical Model ◽  
Model Parameters ◽  
Area Index

Abstract. Assimilation of in situ and satellite data in mechanistic terrestrial ecosystem models helps to constrain critical model parameters and reduce uncertainties in the simulated energy, water and carbon fluxes. So far the assimilation of eddy covariance measurements from flux-tower sites has been conducted mostly for individual sites ("single-site" optimization). Here we develop a variational data assimilation system to optimize 21 parameters of the ORCHIDEE biogeochemical model, using net CO2 flux (NEE) and latent heat flux (LE) measurements from 12 temperate deciduous broadleaf forest sites. We assess the potential of the model to simulate, with a single set of inverted parameters, the carbon and water fluxes at these 12 sites. We compare the fluxes obtained from this "multi-site" (MS) optimization to those of the prior model, and of the "single-site" (SS) optimizations. The model-data fit analysis shows that the MS approach decreases the daily root-mean-square difference (RMS) to observed data by 22%, which is close to the SS optimizations (25% on average). We also show that the MS approach distinctively improves the simulation of the ecosystem respiration (Reco), and to a lesser extent the gross primary productivity (GPP), although we only assimilated net CO2 flux. A process-oriented parameter analysis indicates that the MS inversion system finds a unique combination of parameters which is not the simple average of the different SS sets of parameters. Finally, in an attempt to validate the optimized model against independent data, we observe that global-scale simulations with MS optimized parameters show an enhanced phase agreement between modeled leaf area index (LAI) and satellite-based observations of normalized difference vegetation index (NDVI).

scholarly journals Quantifying the UK's carbon dioxide flux: an atmospheric inverse modelling approach using a regional measurement network

2019 ◽  
Vol 19 (7) ◽  
pp. 4345-4365 ◽  
Author(s):  
Emily D. White ◽  
Matthew Rigby ◽  
Mark F. Lunt ◽  
T. Luke Smallman ◽  
Edward Comyn-Platt ◽  
...  
Keyword(s):  
Carbon Dioxide ◽  
Transport Model ◽  
Ecosystem Respiration ◽  
Atmospheric Dispersion ◽  
Terrestrial Ecosystem ◽  
Carbon Dioxide Flux ◽  
Inverse Modelling ◽  
Chemical Transport Model ◽  
The Uk ◽  
The Impact

Abstract. We present a method to derive atmospheric-observation-based estimates of carbon dioxide (CO2) fluxes at the national scale, demonstrated using data from a network of surface tall-tower sites across the UK and Ireland over the period 2013–2014. The inversion is carried out using simulations from a Lagrangian chemical transport model and an innovative hierarchical Bayesian Markov chain Monte Carlo (MCMC) framework, which addresses some of the traditional problems faced by inverse modelling studies, such as subjectivity in the specification of model and prior uncertainties. Biospheric fluxes related to gross primary productivity and terrestrial ecosystem respiration are solved separately in the inversion and then combined a posteriori to determine net ecosystem exchange of CO2. Two different models, Data Assimilation Linked Ecosystem Carbon (DALEC) and Joint UK Land Environment Simulator (JULES), provide prior estimates for these fluxes. We carry out separate inversions to assess the impact of these different priors on the posterior flux estimates and evaluate the differences between the prior and posterior estimates in terms of missing model components. The Numerical Atmospheric dispersion Modelling Environment (NAME) is used to relate fluxes to the measurements taken across the regional network. Posterior CO2 estimates from the two inversions agree within estimated uncertainties, despite large differences in the prior fluxes from the different models. With our method, averaging results from 2013 and 2014, we find a total annual net biospheric flux for the UK of 8±79 Tg CO2 yr−1 (DALEC prior) and 64±85 Tg CO2 yr−1 (JULES prior), where negative values represent an uptake of CO2. These biospheric CO2 estimates show that annual UK biospheric sources and sinks are roughly in balance. These annual mean estimates consistently indicate a greater net release of CO2 than the prior estimates, which show much more pronounced uptake in summer months.

scholarly journals Warming homogenizes apparent temperature sensitivity of ecosystem respiration

2021 ◽  
Vol 7 (15) ◽  
pp. eabc7358
Author(s):  
Ben Niu ◽  
Xianzhou Zhang ◽  
Shilong Piao ◽  
Ivan A. Janssens ◽  
Gang Fu ◽  
...  
Keyword(s):  
Temperature Sensitivity ◽  
Ecosystem Respiration ◽  
Meta Analysis ◽  
Spatial Relationship ◽  
Terrestrial Ecosystem ◽  
Apparent Temperature ◽  
Carbon Loss ◽  
High Emission ◽  
Higher Temperature ◽  
Warming World

Warming-induced carbon loss through terrestrial ecosystem respiration (Re) is likely getting stronger in high latitudes and cold regions because of the more rapid warming and higher temperature sensitivity of Re (Q10). However, it is not known whether the spatial relationship between Q10 and temperature also holds temporally under a future warmer climate. Here, we analyzed apparent Q10 values derived from multiyear observations at 74 FLUXNET sites spanning diverse climates and biomes. We found warming-induced decline in Q10 is stronger at colder regions than other locations, which is consistent with a meta-analysis of 54 field warming experiments across the globe. We predict future warming will shrink the global variability of Q10 values to an average of 1.44 across the globe under a high emission trajectory (RCP 8.5) by the end of the century. Therefore, warming-induced carbon loss may be less than previously assumed because of Q10 homogenization in a warming world.

MODIS-Based Estimates of Global Terrestrial Ecosystem Respiration

2018 ◽  
Vol 123 (2) ◽  
pp. 326-352 ◽  
Author(s):  
Jinlong Ai ◽  
Gensuo Jia ◽  
Howard E. Epstein ◽  
Hesong Wang ◽  
Anzhi Zhang ◽  
...  
Keyword(s):  
Ecosystem Respiration ◽  
Terrestrial Ecosystem
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