Search

Lexun Wang,1 Lei Xiang,1,2 Shenghua Piao,1 Xiao Gong,3 Wanxing Zhou,4 Weixun Feng,5 Huilin Li,6 Leyu Li,7 Aisheng Wei,8 Qing Zhu,1 Xianglu Rong,1 Jiao Guo1,2 1Guangdong Metabolic Diseases Research Center of Integrated Chinese and Western Medicine; Key Laboratory of Glucolipid Metabolic Disorder, Ministry of Education of China; Institute of Chinese Medicine, Guangdong Pharmaceutical University; Guangdong TCM Key Laboratory for Metabolic Diseases, Guangzhou, People’s Republic of China; 2The First Affiliated Hospital of Guangdong Pharmaceutical University, Guangzhou, People’s Republic of China; 3School of Public Health, Guangdong Pharmaceutical University, Guangzhou, People’s Republic of China; 4Department of Internal Cardiology, The First Affiliated Hospital of Guangdong Pharmaceutical University, Guangzhou, People’s Republic of China; 5Famous Doctor’s Studio, Qingyuan Hospital of Traditional Chinese Medicine, Qingyuan, People’s Republic of China; 6Department of Endocrinology, Shenzhen Traditional Chinese Medicine Hospital, The Fourth Clinical Medical College of Guangzhou University of Chinese Medicine, Shenzhen, People’s Republic of China; 7Department of Endocrinology, Zhongshan Hospital of Traditional Chinese Medicine, Zhongshan, People’s Republic of China; 8Department of Endocrinology, Foshan Hospital of Traditional Chinese Medicine, Foshan, People’s Republic of ChinaCorrespondence: Jiao GuoGuangdong Metabolic Diseases Research Center of Integrated Chinese and Western Medicine; Key Laboratory of Glucolipid Metabolic Disorder, Ministry of Education of China; Institute of Chinese Medicine, Guangdong Pharmaceutical University; Guangdong TCM Key Laboratory for Metabolic Diseases, Guangzhou, People’s Republic of ChinaTel +86-02-39352818Fax +86-02-39352607Email gyguoyz@163.comBackground: Diabetic coronary heart disease (DCHD), the main macrovascular complication of type 2 diabetes mellitus (T2DM), is greatly harmful to T2DM patients. Traditional Chinese medicine (TCM) is an alternative and effective therapy to delay the development of macrovascular diseases, but the existing evidence of its efficacy and safety is insufficient. The aim of this multicenter, randomized, double-blind, placebo-controlled trial is to evaluate the efficacy and safety of Chinese Medicine Fufang Zhenzhu Tiaozhi capsule (FTZ) in treating DCHD.Patients and Methods: This study includes a 2-week run-in, 52-week treatment, and 52-week post-treatment follow-up. A total of 160 participants will be recruited and randomized into two groups. The treatment group will receive FTZ and basic treatment, while the control group will receive the placebo and basic treatment. The primary outcome is the combined outcome including the major adverse cardiovascular events, coronary restenosis, and unplanned revascularization. The combined secondary outcomes include all-cause mortality, acute coronary syndrome, ischemic stroke, heart failure, unplanned re-hospitalization mainly caused by acute complications of diabetes, other thromboembolic events, and TCM symptom indicators. The safety outcomes and adverse events will also be evaluated in this trial.Discussion: This trial evaluates the clinical effectiveness and safety of FTZ in patients with DCHD. The results are important to further explore the effectiveness of the comprehensive strategy “Tiao Gan Qi Shu Hua Zhuo” (modulating Gan, trigging key metabolic system to resolve pathogenic factors such as phlegm retention and dampness) in the prevention and control of glucolipid metabolic disorders (GLMD) including DCHD and T2DM. On the other hand, this study is the first trial of FTZ to observe cardiovascular outcomes through long-term follow-up after treatment of DCHD, which is of great value.Trial Registration: This trial was registered in the Chinese Clinical Trial Registry on April 07, 2019 (No. ChiCTR1900022345).Keywords: type 2 diabetes mellitus, traditional Chinese medicine, clinical study

The global land and ocean carbon sinks have increased proportionally with increasing carbon dioxide emissions during the past decades.sup.1. It is thought that Northern Hemisphere lands make a dominant contribution to the global land carbon sink.sup.2-7; however, the long-term trend of the northern land sink remains uncertain. Here, using measurements of the interhemispheric gradient of atmospheric carbon dioxide from 1958 to 2016, we show that the northern land sink remained stable between the 1960s and the late 1980s, then increased by 0.5 [plus or minus] 0.4 petagrams of carbon per year during the 1990s and by 0.6 [plus or minus] 0.5 petagrams of carbon per year during the 2000s. The increase of the northern land sink in the 1990s accounts for 65% of the increase in the global land carbon flux during that period. The subsequent increase in the 2000s is larger than the increase in the global land carbon flux, suggesting a coincident decrease of carbon uptake in the Southern Hemisphere. Comparison of our findings with the simulations of an ensemble of terrestrial carbon models.sup.5,8 over the same period suggests that the decadal change in the northern land sink between the 1960s and the 1990s can be explained by a combination of increasing concentrations of atmospheric carbon dioxide, climate variability and changes in land cover. However, the increase during the 2000s is underestimated by all models, which suggests the need for improved consideration of changes in drivers such as nitrogen deposition, diffuse light and land-use change. Overall, our findings underscore the importance of Northern Hemispheric land as a carbon sink. Measurements of the interhemispheric gradient of atmospheric carbon dioxide show that the Northern Hemisphere carbon land sink remained stable between the 1960s and the late 1980s, then increased during the 1990s and 2000s., Author(s): P. Ciais [sup.1] [sup.2] , J. Tan [sup.2] , X. Wang [sup.2] , C. Roedenbeck [sup.3] , F. Chevallier [sup.1] , S.-L. Piao [sup.2] [sup.4] , R. Moriarty [sup.5] [...]

In China, irrigation is widespread in 40.7% cropland to sustain crop yields. By its action on water cycle, irrigation affects water resources and local climate. In this study, a new irrigation module, including flood and paddy irrigation technologies, was developed in the ORCHIDEE‐CROP land surface model which describes crop phenology and growth in order to estimate irrigation demands over China from 1982 to 2014. Three simulations were performed including NI (no irrigation), IR (with irrigation limited by local water resources), and FI (with irrigation demand fulfilled). Observations and census data were used to validate the simulations. Results showed that the estimated irrigation water withdrawal (W) based on IR and FI scenarios bracket statistical W with fair spatial agreements (r=0.68±0.07; p<0.01). Improving irrigation efficiency was found to be the dominant factor leading to the observed W decrease. By comparing simulated total water storage (TWS) with GRACE observations, we found that simulated TWS with irrigation well explained the TWS variation over China. However, our simulation overestimated the seasonality of TWS in the Yangtze River Basin due to ignoring regulation of artificial reservoirs. The observed TWS decrease in the Yellow River Basin caused by groundwater depletion was not totally captured in our simulation, but it can be inferred by combining simulated TWS with census data. Moreover, we demonstrated that land use change tended to drive W locally but had little effect on total W over China due to water resources limitation. Key Points: A new irrigation module is developed in ORCHIDEE including drip, flood, and paddy irrigationSimulations can explain broad scale patterns and the trends of irrigation amount from census dataIrrigation efficiency and land use change are key factors affecting the trend of irrigation [ABSTRACT FROM AUTHOR]

The global land and ocean carbon sinks have increased proportionally with increasing carbon dioxide emissions during the past decades1. It is thought that Northern Hemisphere lands make a dominant contribution to the global land carbon sink2–7; however, the long-term trend of the northern land sink remains uncertain. Here, using measurements of the interhemispheric gradient of atmospheric carbon dioxide from 1958 to 2016, we show that the northern land sink remained stable between the 1960s and the late 1980s, then increased by 0.5 ± 0.4 petagrams of carbon per year during the 1990s and by 0.6 ± 0.5 petagrams of carbon per year during the 2000s. The increase of the northern land sink in the 1990s accounts for 65% of the increase in the global land carbon flux during that period. The subsequent increase in the 2000s is larger than the increase in the global land carbon flux, suggesting a coincident decrease of carbon uptake in the Southern Hemisphere. Comparison of our findings with the simulations of an ensemble of terrestrial carbon models5,8 over the same period suggests that the decadal change in the northern land sink between the 1960s and the 1990s can be explained by a combination of increasing concentrations of atmospheric carbon dioxide, climate variability and changes in land cover. However, the increase during the 2000s is underestimated by all models, which suggests the need for improved consideration of changes in drivers such as nitrogen deposition, diffuse light and land-use change. Overall, our findings underscore the importance of Northern Hemispheric land as a carbon sink. Measurements of the interhemispheric gradient of atmospheric carbon dioxide show that the Northern Hemisphere carbon land sink remained stable between the 1960s and the late 1980s, then increased during the 1990s and 2000s. [ABSTRACT FROM AUTHOR]

The terrestrial biosphere shows substantial inertia in its response to environmental change. Hence, assessments of transient changes in ecosystem properties to 2100 do not capture the full magnitude of the response realized once ecosystems reach an effective equilibrium with the changed environmental boundary conditions. This equilibrium state can be termed the committed state, in contrast to a transient state in which the ecosystem is in disequilibrium. The difference in ecosystem properties between the transient and committed states represents the committed change yet to be realized. Here an ensemble of dynamic global vegetation model simulations was used to assess the changes in tree cover and carbon storage for a variety of committed states, relative to a preindustrial baseline, and to attribute the drivers of uncertainty. Using a subset of simulations, the committed changes in these variables post‐2100, assuming climate stabilization, were calculated. The results show large committed changes in tree cover and carbon storage, with model disparities driven by residence time in the tropics, and residence time and productivity in the boreal. Large changes remain ongoing well beyond the end of the 21st century. In boreal ecosystems, the simulated increase in vegetation carbon storage above preindustrial levels was 20–95 Pg C at 2 K of warming, and 45–201 Pg C at 5 K, of which 38–155 Pg C was due to expansion in tree cover. Reducing the large uncertainties in long‐term commitment and rate‐of‐change of terrestrial carbon uptake will be crucial for assessments of emissions budgets consistent with limiting climate change. Plain Language Summary: Changes in climate and atmospheric carbon dioxide concentration affect ecosystems. One result of these effects, projected by most vegetation models, is that the global land biosphere is expected to continue to provide a net uptake of carbon dioxide throughout the 21st century. Characterizing this is important for policy, as it influences the amount of carbon dioxide emissions reductions needed to limit global warming. However, the effects of such environmental changes on land ecosystems are not all realized instantly. Ecosystems may continue to react to a change in their wider environment for decades or centuries after that change has occurred. These delayed reactions are termed the committed change. We found widespread agreement among multiple vegetation models that land in the far north will continue to take up a large amount of carbon in the long‐term, as a result of committed responses to climate change and carbon dioxide increases. The magnitude of uptake varied between simulations and was partially driven by an advance of the northern treeline. A less consistent model response was found in the tropics. The large amount of carbon involved, and associated climate policy implications, illustrates the benefits of further measurements leading to more accurate vegetation model calibration. Key Points: Terrestrial vegetation composition and carbon storage continue to change very substantially after stabilization of climateUncertainty in this committed carbon uptake is of the order of several hundred Pg C, complicating emission budget calculationsVegetation dynamics need to be more routinely represented in the coupled Earth System Models used to make climate projections [ABSTRACT FROM AUTHOR]

The fat quality is an important aspect, especially for Wagyu beef. A handheld fiber-optic near-infrared spectrometer for on-site evaluation of beef fat quality was developed, and the interactance spectra of the intermuscular fat from 833 Wagyu carcasses at 12 markets were measured. The calibration model was transferred to five slave instruments using twenty-six block samples. The performance of one slave instrument was verified at five meat markets (n = 360). The coefficients of determination of the slave instrument for monounsaturated, oleic, and saturated fatty acid compositions determined by gas chromatography and near-infrared measurements were 0.69, 0.64, and 0.67, respectively. The standard error of prediction for the slave instrument was approximately 2%. The fiber-optic near-infrared spectrometers were highly accurate in the fat quality evaluation of Wagyu carcasses based on monounsaturated, oleic, and saturated fatty acid composition with easy calibration model transfer. [ABSTRACT FROM AUTHOR]

Methane (CH4) has a 28-fold greater global warming potential than CO2 over one hundred years. Atmospheric CH4 concentration has tripled since 1750. Anthropogenic CH4 emissions from China has been growing rapidly in the past decades, and contributes more than 10 % of global anthropogenic CH4 emissions with large uncertainties in existing global inventories, generally limited to country-scale statistics. To date, a long-term CH4 emissions inventory including the major sources sectors and based on province-level emission factors is still lacking. In this study, we produced a detailed bottom-up inventory of anthropogenic CH4 emissions from the eight major source sectors in China for the period 1980-2010. In the past three decades, the total CH4 emissions increased from 22.2 [16.6-28.2] Tg CH4 yr-1 (mean [minimum-maximum of 95 % confidence interval]) to 45.0 [36.4-58.3] Tg CH4 yr-1, and most of this increase took place in the 2000s. This fast increase of the total CH4 emissions after 2000 is mainly driven by CH4 emissions from coal exploitation. The largest contribution to total CH4 emissions also shifted from rice cultivation in 1980 to coal exploitation in 2010. The total emissions inferred in this work compare well with the EPA inventory but appear to be 38 % lower than EDGAR4.2 inventory. The uncertainty of our inventory is investigated using emissions factors collected from published literatures. We also distributed province-scale emissions into 0.5° × 0.5° maps using social-economic activity data. This new inventory could help understanding CH4 budgets at regional scale and guiding CH4 mitigation policies in China. [ABSTRACT FROM AUTHOR]

Boreal fires have immediate effects on regional carbon budgets by emitting CO2 into the atmosphere at the time of burning, but they also have legacy effects by initiating a long-term carbon sink during post-fire vegetation recovery. Quantifying these different effects on the current-day pan-boreal (44-84° N) carbon balance and quantifying relative contributions of legacy sinks by past fires is important for understanding and predicting the carbon dynamics in this region. Here we used the global dynamic vegetation model ORCHIDEE-SPITFIRE (Organising Carbon and Hydrology In Dynamic Ecosystems - SPread and InTensity of FIRE) to attribute the contributions by fires in different decades between 1850 and 2009 to the carbon balance of 2000-2009, taking into account the atmospheric CO2 change and climate change since 1850. The fire module of ORCHIDEE- SPITFIRE was turned off for each decade in turn and was also turned off before and after the decade in question in order to model the legacy carbon trajectory by fires in each past decade. We found that, unsurprisingly, fires that occurred in 2000-2009 are a carbon source (-0.17 Pg C yr-1) for the carbon balance of 2000-2009, whereas fires in all decades before 2000 contribute carbon sinks with a collective contribution of 0.23 Pg C yr-1. This leaves a net fire sink effect of 0.06 Pg Cyr-1, or 6.3% of the simulated regional carbon sink (0.95 Pg C yr-1/. Further, fires with an age of 10-40 years (i.e., those that occurred during 1960-1999) contribute more than half of the total sink effect of fires. The small net sink effect of fires indicates that current-day fire emissions are roughly balanced out by legacy sinks. The future role of fires in the regional carbon balance remains uncertain and will depend on whether changes in fires and associated carbon emissions will exceed the enhanced sink effects of previous fires, both being strongly affected by global change. [ABSTRACT FROM AUTHOR]

Processes that describe the distribution of vegetation and ecosystem succession after disturbance are an important component of dynamic global vegetation models (DGVMs). The vegetation dynamics module (ORC-VD) within the process-based ecosystem model ORCHIDEE (Organizing Carbon and Hydrology in Dynamic Ecosystems) has not been updated and evaluated since many years and is known to produce unrealistic results. This study presents a new parameterization of ORC-VD for mid- to high-latitude regions in the Northern Hemisphere, including processes that influence the existence, mortality and competition between tree functional types. A new set of metrics is also proposed to quantify the performance of ORC-VD, using up to five different data sets of satellite land cover, forest biomass from remote sensing and inventories, a data-driven estimate of gross primary productivity (GPP) and two gridded data sets of soil organic carbon content. The scoring of ORC-VD derived from these metrics integrates uncertainties in the observational data sets. This multi-data set evaluation framework is a generic method that could be applied to the evaluation of other DGVM models. The results of the original ORC-VD published in 2005 for mid- to high-latitudes and of the new parameterization are evaluated against the above-described data sets. Significant improvements were found in the modeling of the distribution of tree functional types north of 40° N. Three additional sensitivity runs were carried out to separate the impact of different processes or drivers on simulated vegetation vegetation distribution, including soil freezing which limits net primary production through soil moisture availability in the root zone, elevated CO2 concentration since 1850, and the effects of frequency and severity of extreme cold events during the spin-up phase of the model. [ABSTRACT FROM AUTHOR]

The hollow structured magnetic CoFe2O4 nanoparticles were synthesized by a facile hydrothermal method, and their magnetorheological (MR) characteristics were investigated in this paper. From transmission electron microscopy and density measurements, it was found that the CoFe2O4 nanoparticles possess a spherical shape with a narrow size distribution with a low density of 4.46 g/cm $^{{ {3}}}$ . The MR fluid was then prepared by dispersing CoFe2O4 nanoparticles in mineral oil. Under applied magnetic fields, its rheological properties, such as shear stress, shear viscosity, storage modulus, and yield stress, were investigated via a rotational rheometer with a parallel-plate geometry. In addition, suspension stability of the CoFe2O4-based MR fluid was also examined by a Turbiscan apparatus, demonstrating that the CoFe2O4 suspension has good dispersion stability due to the unique hollow architecture and the relatively low density. [ABSTRACT FROM AUTHOR]

Plants acquire carbon through photosynthesis to sustain biomass production, autotrophic respiration and production of non-structural compounds for multiple purposes. The fraction of photosynthetic production used for biomass production, the biomass production efficiency, is a key determinant of the conversion of solar energy to biomass. In forest ecosystems, biomass production efficiency was suggested to be related to site fertility. Here we present a database of biomass production efficiency from 131 sites compiled from individual studies using harvest, biometric, eddy covariance, or process-based model estimates of production. The database is global, but dominated by data from Europe and North America. We show that instead of site fertility, ecosystem management is the key factor that controls biomass production efficiency in terrestrial ecosystems. In addition, in natural forests, grasslands, tundra, boreal peatlands and marshes, biomass production efficiency is independent of vegetation, environmental and climatic drivers. This similarity of biomass production efficiency across natural ecosystem types suggests that the ratio of biomass production to gross primary productivity is constant across natural ecosystems. We suggest that plant adaptation results in similar growth efficiency in high- and low-fertility natural systems, but that nutrient influxes under managed conditions favour a shift to carbon investment from the belowground flux of non-structural compounds to aboveground biomass. [ABSTRACT FROM AUTHOR]

Since the mid-20th century, nitrogen (N) deposition has shown an increasing trend in the Tibetan Plateau (TP), where alpine ecosystems are sensitive to elevated N deposition. However, the quantitative characterization of N deposition in the TP remains unclear, due in most part to the lack of in situ measurement. Using the Tibetan Observation and Research Platform network, we conducted shortterm in situ measurements of major ions (NO-3, Cl-, SO2-4, NH+4, Na+, K+, Ca2+, and Mg2+/ wet deposition at five remote sites in the TP during 2011-2013. At Southeast Tibet Station, Nam Co Station, Qomolangma Station, Ngari Station, and Muztagh Ata Station, the NH+4 -N wet deposition was 0.63, 0.68, 0.92, 0.36, and 1.25 kgNha-1 yr-1, respectively; the NO-3 -N wet deposition was 0.28, 0.24, 0.03, 0.08, and 0.30 kgNha-1 yr-1, respectively; and the inorganic N wet deposition was 0.91, 0.92, 0.94, 0.44, and 1.55 kgNha-1 yr-1, respectively. The inorganic N wet deposition mainly occurred in the form of NH+4 -N during summer at all sites. Results of enrichment factor analysis and principal component analysis demonstrated that both NH+4 - N and NO-3 -N wet deposition in the TP were mainly influenced by anthropogenic activities. Backward trajectory analysis showed that the inorganic N deposition at Muztagh Ata Station was mainly transported from central Asia and the Middle East through westerlies. At Southeast Tibet Station, Nam Co Station, Qomolangma Station, and Ngari Station, the inorganic N deposition was mainly contributed by anthropogenic sources in south Asia, and was mainly transported by the Indian monsoon. Combining site-scale in situ measurements of inorganic N wet deposition in this and previous studies, the average wet deposition of atmospheric NH+4 - N, NO-3 -N, and inorganic N in the TP was estimated to be 1.06, 0.51, and 1.58 kgNha-1 yr-1, respectively. The average NH+4 -N : NO-3 -N ratio in precipitation in the TP was approximately 2 : 1. Results from the present study suggest that earlier estimations based on chemical transport model simulations and/or limited field measurements likely overestimated substantially the regional inorganic N wet deposition in the TP. To clarify the total N deposition in the TP more clearly, it is essential to conduct long-term monitoring of both wet and dry deposition of atmospheric N in various climate zones in the TP in the future. [ABSTRACT FROM AUTHOR]

Boreal fires have immediate effects on regional carbon budgets by emitting CO2 into the atmosphere at the time of burning, but also have legacy effects by initiating a long-term carbon sink during post-fire vegetation recovery. Quantifying these different effects on the current-day pan-boreal (44-84° N) carbon balance and relative contributions of legacy sinks by past fires is important for understanding and predicting the carbon dynamics in this region. Here we used the global dynamic vegetation model ORCHIDEE-SPITFIRE to attribute the contributions by fires in different decades of 1850-2009 to the carbon balance of 2000-2009, taking into account the atmospheric CO2 change and climate change since 1850. The fire module of ORCHIDEE-SPITFIRE was turned off in each decade sequentially, and turned on before and after, to model the legacy carbon trajectory by fires in each past decade. We found that, unsurprisingly, fires that occurred in 2000-2009 are a carbon source (-0.17 Pg C yr-1) for the 2000s-decade carbon balance, whereas fires in all decades before 2000 contribute carbon sinks with a collective contribution of 0.23 Pg C yr-1. This leaves a net fire sink effect of 0.06 Pg C yr-1, or 6.3% of the simulated regional carbon sink (0.95 Pg C yr-1). Further, fires with an age of 10-40 years (i.e. those occurred during 1960-1999) contribute more than half of the total sink effect of fires. The small net sink effect of fires indicates that current-day fire emissions are roughly in balance with legacy sinks. The future role of fires in the regional carbon balance remains uncertain and will depend on whether changes in fires and associated carbon emissions will exceed the enhanced sink effects of previous fires, both being strongly affected by global change. [ABSTRACT FROM AUTHOR]

Alpine ecosystems on the Tibetan Plateau are sensitive to elevated nitrogen (N) deposition, and N wet deposition in this region has shown an increasing trend since the mid-20th century. However, the amount of N wet deposition on the Tibetan remains unclear, due in most part to the lack of direct observations. Using the Tibetan Observation and Research Platform network, we investigated wet deposition of the major ions (NO3-, Cl-, SO42-, NH4+, Na+, K+, Ca2+ and Mg2+) at five remote stations. At Southeast Tibet Station, Nam Co Station, Qomolangma Station, Ngari Station, and Muztagh Ata Station, the NH4+-N wet deposition was 0.63, 0.91, 1.61, 0.36 and 1.25 kg N ha-1 yr-1, respectively; the NO3--N wet deposition was 0.28, 0.35, 0.04, 0.08 and 0.3 kg N ha-1 yr-1, respectively; and the inorganic N deposition was 0.91, 1.26, 1.64, 0.44 and 1.55 kg N ha-1 yr-1, respectively. Combining our field observations with previous studies, the average wet deposition of atmospheric NH4+-N, NO3--N, and inorganic N on the Tibetan Plateau was estimated to be 1.17, 0.58 and 1.75 kg N ha-1 yr-1, respectively. The estimated NH4+-N : NO3--N ratio in precipitation on the Tibetan Plateau was 2 : 1. Compared to the present study, the inorganic N wet deposition for the entire Tibetan Plateau in previous studies, either through atmospheric chemistry transport model simulations or interpolations based on limited observations, has been highly overestimated. To clarify the total N deposition on the Tibetan Plateau, it is necessary to conduct long-term and large-scale monitoring of both wet and dry deposition of N in the future. [ABSTRACT FROM AUTHOR]

Processes that describe the distribution of vegetation and ecosystem succession after disturbance are an important component of dynamic global vegetation models (DGVMs). The vegetation dynamics module (ORC-VD) within the process-based ecosystem model ORCHIDEE (Organizing Carbon and Hydrology in Dynamic Ecosystems) has not been updated and evaluated since many years and does not match the progress in modeling the rest of the physical and biogeochemical processes. Therefore, ORC-VD is known to produce unrealistic results. This study presents a new parameterization of ORC-VD for mid-to-high latitude regions in the Northern Hemisphere, including processes that influence the existence, mortality and competition between tree functional types. A new set of metrics is also proposed to quantify the performance of ORC-VD, using up to five different datasets of satellite land cover, forest biomass from remote sensing and inventories, a data-driven estimate of gross primary productivity (GPP) and two gridded datasets of soil organic carbon content. The scoring of ORC-VD derived from these metrics integrates uncertainties in the observational datasets. This multi-dataset evaluation framework is a generic method that could be applied to the evaluation of other DGVM models. The results of the original ORC-VD published in 2005 for mid-to-high latitudes and of the new parameterization are evaluated against the above-described datasets. Significant improvements were found in the modeling of the distribution of tree functional types north of 40° N. Three additional sensitivity runs were carried out to separate the impact of different processes or drivers on simulated vegetation distribution, including soil freezing which limits net primary production through soil moisture availability in the root zone, elevated CO2 concentration since 1850, and the return frequency of cold climate extremes causing tree mortality during the spin-up phase of the model. [ABSTRACT FROM AUTHOR]

Forests strongly affect climate through the exchange of large amounts of atmospheric CO2 (ref. ). The main drivers of spatial variability in net ecosystem production (NEP) on a global scale are, however, poorly known. As increasing nutrient availability increases the production of biomass per unit of photosynthesis and reduces heterotrophic respiration in forests, we expected nutrients to determine carbon sequestration in forests. Our synthesis study of 92 forests in different climate zones revealed that nutrient availability indeed plays a crucial role in determining NEP and ecosystem carbon-use efficiency (CUEe; that is, the ratio of NEP to gross primary production (GPP)). Forests with high GPP exhibited high NEP only in nutrient-rich forests (CUEe = 33 ± 4%; mean ± s.e.m.). In nutrient-poor forests, a much larger proportion of GPP was released through ecosystem respiration, resulting in lower CUEe (6 ± 4%). Our finding that nutrient availability exerts a stronger control on NEP than on carbon input (GPP) conflicts with assumptions of nearly all global coupled carbon cycle-climate models, which assume that carbon inputs through photosynthesis drive biomass production and carbon sequestration. An improved global understanding of nutrient availability would therefore greatly improve carbon cycle modelling and should become a critical focus for future research. [ABSTRACT FROM AUTHOR]

Concentrations of atmospheric carbon dioxide (CO2) have continued to increase whereas atmospheric deposition of sulphur and nitrogen has declined in Europe and the USA during recent decades. Using time series of flux observations from 23 forests distributed throughout Europe and the USA, and generalised mixed models, we found that forest-level net ecosystem production and gross primary production have increased by 1% annually from 1995 to 2011. Statistical models indicated that increasing atmospheric CO2 was the most important factor driving the increasing strength of carbon sinks in these forests. We also found that the reduction of sulphur deposition in Europe and the USA lead to higher recovery in ecosystem respiration than in gross primary production, thus limiting the increase of carbon sequestration. By contrast, trends in climate and nitrogen deposition did not significantly contribute to changing carbon fluxes during the studied period. Our findings support the hypothesis of a general CO2-fertilization effect on vegetation growth and suggest that, so far unknown, sulphur deposition plays a significant role in the carbon balance of forests in industrialized regions. Our results show the need to include the effects of changing atmospheric composition, beyond CO2, to assess future dynamics of carbon-climate feedbacks not currently considered in earth system/climate modelling.

Stand-replacing fires are the dominant fire type in North American boreal forests. They leave a historical legacy of a mosaic landscape of different aged forest cohorts. This forest age dynamics must be included in vegetation models to accurately quantify the role of fire in the historical and current regional forest carbon balance. The present study adapted the global process-based vegetation model ORCHIDEE to simulate the CO2 emissions from boreal forest fire and the subsequent recovery after a stand-replacing fire; the model represents postfire new cohort establishment, forest stand structure and the self-thinning process. Simulation results are evaluated against observations of three clusters of postfire forest chronosequences in Canada and Alaska. The variables evaluated include: fire carbon emissions, CO2 fluxes (gross primary production, total ecosystem respiration and net ecosystem exchange), leaf area index, and biometric measurements (aboveground biomass carbon, forest floor carbon, woody debris carbon, stand individual density, stand basal area, and mean diameter at breast height). When forced by local climate and the atmospheric CO2 history at each chronosequence site, the model simulations generally match the observed CO2 fluxes and carbon stock data well, with model-measurement mean square root of deviation comparable with the measurement accuracy (for CO2 flux ~100 g C m-2 yr-1, for biomass carbon ~1000 g C m-2 and for soil carbon ~2000 g C m-2). We find that the current postfire forest carbon sink at the evaluation sites, as observed by chronosequence methods, is mainly due to a combination of historical CO2 increase and forest succession. Climate change and variability during this period offsets some of these expected carbon gains. The negative impacts of climate were a likely consequence of increasing water stress caused by significant temperature increases that were not matched by concurrent increases in precipitation. Our simulation results demonstrate that a global vegetation model such as ORCHIDEE is able to capture the essential ecosystem processes in fire-disturbed boreal forests and produces satisfactory results in terms of both carbon fluxes and carbon-stock evolution after fire. This makes the model suitable for regional simulations in boreal regions where fire regimes play a key role in the ecosystem carbon balance. [ABSTRACT FROM AUTHOR]

Climate change policies need to consider the contribution of each emitting region to the increase in atmospheric carbon dioxide. We calculate regional attributions of increased atmospheric CO2 using two different assumptions about land sinks. In the first approach, each absorber region is attributed 'domestic sinks' that occur within its boundaries. In the second, alternative approach, each emitter region is attributed 'foreign sinks' that it created indirectly through its contribution to increasing CO2. We unambiguously attribute the largest share of the historical increase in CO2 between pre-industrial times and the present-day period to developed countries. However, the excess CO2 in the atmosphere since pre-industrial times attributed to developing countries is greater than their share of cumulative CO2 emissions. This is because a greater fraction of their emissions occurred more recently. If emissions remain high over the coming decades, the share of excess CO2 attributable to developing countries will grow, and the sink service provided by forested regions-in particular those with tropical forest-to other regions will depend critically on future tropical land-use change. [ABSTRACT FROM AUTHOR]

Global temperature is increasing, especially over northern lands (>50° N), owing to positive feedbacks. As this increase is most pronounced in winter, temperature seasonality (ST)-conventionally defined as the difference between summer and winter temperatures-is diminishing over time, a phenomenon that is analogous to its equatorward decline at an annual scale. The initiation, termination and performance of vegetation photosynthetic activity are tied to threshold temperatures. Trends in the timing of these thresholds and cumulative temperatures above them may alter vegetation productivity, or modify vegetation seasonality (SV), over time. The relationship between ST and SV is critically examined here with newly improved ground and satellite data sets. The observed diminishment of ST and SV is equivalent to 4° and 7° (5° and 6°) latitudinal shift equatorward during the past 30 years in the Arctic (boreal) region. Analysis of simulations from 17 state-of-the-art climate models indicates an additional STdiminishment equivalent to a 20° equatorward shift could occur this century. How SV will change in response to such large projected ST declines and the impact this will have on ecosystem services are not well understood. Hence the need for continued monitoring of northern lands as their seasonal temperature profiles evolve to resemble thosefurther south. [ABSTRACT FROM AUTHOR]

The source and sinks of carbon dioxide (CO2) and methane (CH4) due to anthropogenic and natural biospheric activities were estimated for the South Asian region (Bangladesh, Bhutan, India, Nepal, Pakistan and Sri Lanka). Flux estimates were based on top-down methods that use inversions of atmospheric data, and bottom-up methods that use field observations, satellite data, and terrestrial ecosystem models. Based on atmospheric CO2 inversions, the net biospheric CO2 flux in South Asia (equivalent to the Net Biome Productivity, NBP) was a sink, estimated at -104±150 TgCyr-1 during 2007-2008. Based on the bottom-up approach, the net biospheric CO2 flux is estimated to be -191±193 TgCyr -1 during the period of 2000-2009. This last net flux results from the following flux components: (1) the Net Ecosystem Productivity, NEP (net primary production minus heterotrophic respiration) of -220±186 TgCyr -1 (2) the annual net carbon flux from land-use change of -14±50 TgCyr -1, which resulted from a sink of -16 TgCyr -1 due to the establishment of tree plantations and wood harvest, and a source of 2 TgCyr -1 due to the expansion of croplands; (3) the riverine export flux from terrestrial ecosystems to the coastal oceans of +42.9 TgCyr -1; and (4) the net CO2 emission due to biomass burning of +44.1±13.7 TgCyr -1. Including the emissions from the combustion of fossil fuels of 444 TgCyr -1 for the 2000s, we estimate a net CO2 land--atmosphere flux of 297 TgCyr -1. In addition to CO2, a fraction of the sequestered carbon in terrestrial ecosystems is released to the atmosphere as CH4. Based on bottom-up and top-down estimates, and chemistry-transport modeling, we estimate that 37±3.7 TgC-CH4 yr -1 were released to atmosphere from South Asia during the 2000s. Taking all CO2 and CH4 fluxes together, our best estimate of the net land--atmosphere CO2-equivalent flux is a net source of 334 TgCyr-1 for the South Asian region during the 2000s. If CH4 emissions are weighted by radiative forcing of molecular CH4, the total CO2-equivalent flux increases to 1148 TgCyr -1 suggesting there is great potential of reducing CH4 emissions for stabilizing greenhouse gases concentrations. [ABSTRACT FROM AUTHOR]

The source and sinks of carbon dioxide (CO2) and methane (CH4) due to anthropogenic and natural biospheric activities were estimated for the South Asia region (Bangladesh, Bhutan, India, Nepal, Pakistan and Sri Lanka). Flux estimates were based on top-down methods that use inversions of atmospheric data, and bottom-up methods that use field observations, satellite data, and terrestrial ecosystem models. Based on atmospheric CO2 inversions, the net biospheric CO2 flux in South Asia (equivalent to the Net Biome Productivity, NBP) was a sink, estimated at -104±150 TgCyr-1 during 2007-2008. Based on the bottom-up approach, the net biospheric CO2 flux is estimated to be -191±193 TgCyr-1 during the period of 2000-2009. This last net flux results from the following flux components: (1) the Net Ecosystem Productivity, NEP (net primary production minus heterotrophic respiration) of -220±186 TgCyr-1 (2) the annual net carbon flux from land-use change of -14±50 TgCyr-1, which resulted from a sink of -16 TgCyr-1 due to the establishment of tree plantations and wood harvest, and a source of 2 TgCyr-1 due to the expansion of croplands; (3) the riverine export flux from terrestrial ecosystems to the coastal oceans of +42.9 TgCyr-1; and (4) the net CO2 emission due to biomass burning of +44.1±13.7 TgCyr-1. Including the emissions from the combustion of fossil fuels of 444 TgCyr-1 for the decades of 2000s, we estimate a net CO2 land-to-atmosphere flux of 297 TgCyr-1. In addition to CO2, a fraction of the sequestered carbon in terrestrial 20 ecosystems is released to the atmosphere as CH4. Based on bottom-up and top-down estimates, and chemistry-transport modeling, we estimate that 37±3.7 TgC-CH4 yr -1 were released to atmosphere from South Asia during the 2000s. Taking all CO2 and CH4 fluxes together, our best estimate of the net land-to-atmosphere CO2-equivalent flux is a net source of 334 TgCyr-1 for the South Asia region during the 2000s. If CH4 emissions are weighted by radiative forcing of molecular CH4, the total CO2-equivalent flux increases to 1148 TgCyr-1 suggesting there is great potential of reducing CH4 emissions for stabilizing greenhouse gases concentrations. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

High-resolution mapping of fuel combustion and CO2 emission provides valuable information for inferring terrestrial carbon balance, modeling pollutant transport, and developing mitigation strategies. Previous inventories included only a limited number of fuel types and anthropogenic emissions were mapped using national population proxies which may distort the geographical distribution within countries. In this study, a sub-national disaggregation method (SDM) was applied to establish a global 0.1° x 0.1° geo-referenced inventory of fuel combustion (PKU-FUEL) and a corresponding CO2 emission inventory (PKU-CO2) based upon 64 fuel sub-types for the year 2007. Uncertainties of the new inventories were evaluated using a Monte Carlo method. The total combustion CO2 emission in 2007 was 11.2 (9.11 and 13.3 as 5th and 95th percentiles) PgCyr-1. By replacing national disaggregation with sub-national disaggregation in this study, the average 95th minus 5th percentile ranges of CO2 emission for all grids can be reduced from 417 to 68.2Mg km-2 yr-1, indicating a significant reduction in uncertainty, because the uneven distribution of per-capita fuel consumptions within countries has been taken into account by using the sub-national fuel consumption data directly. Significant difference in per-capita CO2 emissions between urban and rural areas was found in developing nations (2.09 vs. 0.600 Mg C cap-1 yr-1), but not in developed ones (3.57 vs. 3.42 Mg C cap-1 yr-1), suggesting strong influence of the rapid urbanization of these countries on the carbon emission. By using the CO2 emission product, a new spatial pattern of terrestrial carbon sink was derived and the impact of sub-national disaggregation is discussed. [ABSTRACT FROM AUTHOR]

Ecology Letters (2012) Abstract Trees with sufficient nutrition are known to allocate carbon preferentially to aboveground plant parts. Our global study of 49 forests revealed an even more fundamental carbon allocation response to nutrient availability: forests with high-nutrient availability use 58 ± 3% (mean ± SE; 17 forests) of their photosynthates for plant biomass production (BP), while forests with low-nutrient availability only convert 42 ± 2% (mean ± SE; 19 forests) of annual photosynthates to biomass. This nutrient effect largely overshadows previously observed differences in carbon allocation patterns among climate zones, forest types and age classes. If forests with low-nutrient availability use 16 ± 4% less of their photosynthates for plant growth, what are these used for? Current knowledge suggests that lower BP per unit photosynthesis in forests with low- versus forests with high-nutrient availability reflects not merely an increase in plant respiration, but likely results from reduced carbon allocation to unaccounted components of net primary production, particularly root symbionts. [ABSTRACT FROM AUTHOR]

Soil moisture availability is important in regulating photosynthesis and controlling land surface-climate feedbacks at both the local and global scale. Recently, global remote-sensing datasets for soil moisture have become available. In this paper we assess the possibility of using remotely sensed soil moisture-AMSR--E (LPRM)--to similate soil moisture dynamics of the process-based vegetation model ORCHIDEE by evaluating the correspondence between these two products using both correlation and autocorrelation analyses. We find that the soil moisture product of AMSR-E (LPRM) and the simulated soil moisture in ORCHIDEE correlate well in space and time, in particular when considering the root zone soil moisture of ORCHIDEE. However, the root zone soil moisture in ORCHIDEE has on average a higher temporal autocorrelation relative to AMSR-E (LPRM) and in situ measurements. This may be due to the different vertical depth of the two products--AMSR-E (LPRM) at the 2-5 cm surface depth and ORCHIDEE at the root zone (max. 2m) depth--to uncertainty in precipitation forcing in ORCHIDEE, and to the fact that the structure of ORCHIDEE consists of a single-layer deep soil, which does not allow simulation of the proper cascade of time scales that characterize soil drying after each rain event. We conclude that assimilating soil moisture, using AMSR-E (LPRM) in a land surface model like ORCHIDEE with an improved hydrological model of more than one soil layer, may significantly improve the soil moisture dynamics, which could lead to improved CO2 and energy flux predictions. [ABSTRACT FROM AUTHOR]

The article looks at the implementation of subgrid soil moisture redistribution scheme based model on TOPMODEL into the ORganizing Carbon and Hydrology in Dynamic EcosystEms (ORCHIDEE) global land surface models (LSM). It explores the development in the ORCHIDEE model as well as analyzes its performance through the classic simulation of streamflow. A comparison of predicted saturated areas against the satellite products is given.

Winter CO2 fluxes represent an important component of the annual carbon budget in northern ecosystems. Understanding winter respiration processes and their responses to climate change is also central to our ability to assess terrestrial carbon cycle and climate feedbacks in the future. However, the factors influencing the spatial and temporal patterns of winter ecosystem respiration (Reco) of northern ecosystems are poorly understood. For this reason, we analyzed eddy covariance flux data from 57 ecosystem sites ranging from ~35° N to ~70° N. Deciduous forests were characterized by the highest winter Reco rates (0.90±0.39 gCm-2 d-1 ), when winter is defined as the period during which daily air temperature remains below 0° C. By contrast, arctic wetlands had the lowest winter Reco rates (0.02±0.02 gCm-2 d-1 ). Mixed forests, evergreen needle-leaved forests, grasslands, croplands and boreal wetlands were characterized by intermediate winter Reco rates (g Cm -2d-1 ) of 0.70(±0.33), 0.60(±0.38), 0.62(±0.43), 0.49(±0.22) and 0.27(±0.08), respectively. Our cross site analysis showed that winter air (Tair) and soil (Tsoil) temperature played a dominating role in determining the spatial patterns of winter R eco in both forest and managed ecosystems (grasslands and croplands). Besides temperature, the seasonal amplitude of the leaf area index (LAI), inferred from satellite observation, or growing season gross primary productivity, which we use here as a proxy for the amount of recent carbon available for R eco in the subsequent winter, played a marginal role in winter CO2 emissions from forest ecosystems. We found that winter R eco sensitivity to temperature variation across space (Q S) was higher than the one over time (interannual, Q T). This can be expected because Q S not only accounts for climate gradients across sites but also for (positively correlated) the spatial variability of substrate quantity. Thus, if the models estimate future warming impacts on R eco based onQ S rather thanQ T, this could overestimate the impact of temperature changes. [ABSTRACT FROM AUTHOR]