Evaluation of Forest Carbon Budget of Liaoning Province in Recent 50 Years

The interannual variation characteristics of NPP and carbon emission of Liaoning forest in recent 50 years (from 1961 to 2008) were analyzed based on the hydrothermal optimized NPP model and soil respiration Q10 model.The results showed that the total amount of annual NPP was increased in recent 50 years,in which the amount of NPP (83.9 Mt) in 2008 was 2.8 times as high as that in 1961.Amount of NPP per unit area changed with different years,and the maximum value was 36.5% more than the minimum one.The net carbon budget of Liaoning forest was carbon sink,with annual 2.1 t CO2/hm2.

Seasonal and inter-annual variations in carbon fluxes and evapotranspiration over cotton field under drip irrigation with plastic mulch in an arid region of Northwest China

Xinjiang is the largest semi-arid and arid region in China, and drip irrigation under plastic mulch is widely used in this water-limited area. Quantifying carbon and water fluxes as well as investigating their environ- mental drivers over cotton fields is critical for understanding regional carbon and water budgets in Xinjiang, the largest cotton production basin of China. In this study, an eddy covariance （EC） technique was used to measure the carbon and water fluxes of cotton field under drip irrigation with plastic mulch in the growing seasons of 2009, 2010, 2012 and 2013 at Wulanwusu Agrometeorological Experiment Station, a representative oasis cropland in northern Xinjiang. The diurnal patterns of gross primary production （GPP）, net ecosystem exchange （NEE） and evapotran-spiration （ET） showed obviously sinusoidal variations from June to September, while the diurnal ecosystem respiration （Res） was stable between daytime and nighttime. The daytime hourly GPP and ET displayed asymptotic rela-tionships with net solar radiation （Rnet）, while showed concave patterns with raising vapor pressure deficit （VPD） and air temperature （Ta）. The increases in hourly GPP and ET towards the maximum occurred over half ranges of VPD and Ta. The seasonal variations of GPP, NEE and ET were close to the cotton phenology, which almost reached the peak value in July. The cumulative GPP averaged 816.2±55.0 g C/m^2 in the growing season （from April to October）, and more than half of GPP was partitioned into NEE （mean value of -478.6±41.4 g C/m^2）. The mean seasonal ET was 501.3±13.9 mm, and the mean water use efficiency （WUE） was 1.0＋0.1 （mg C/g H2O）/d. The agro-ecosystem behaved as a carbon sink from squaring to harvest period, while it acted as a carbon source before the squaring time as well as after the harvest time.

Carbon Budget of Bastard Halibut Paralichthys Olivaceus in Relation to Body Weight and Temperature

The effects of body weight and temperature on the carbon budget of the juvenile bastard halibut,Paralichthys olivaceus, were studied at temperature 13.5, 18, 21.5 and 24 ℃, respectively. The carbon intake, faecal and growth carbon were measured, and the carbon respiration was calculated using the carbon budget equation (C C=G C+F C+R C). The combined relationship between different components of the carbon budget, body weight and temperature could be described by regression equations:C C=1.0206W 0.8126e 0.1483T; G C=0.0042W 1.4096 (-5.11T3+285.90T2-5173.72T+30314.03);F C=0.0485W 0.7711e 0.1624T U C = 1.4333W 0.6715e 0.1487T. Body weight had no significant effect on the carbon absorption efficiency and the conversion efficiency.

Simulating Net Carbon Budget of Forest Ecosystems and Its Response to Climate Change in Northeastern China Using Improved FORCCHN

As dominant biomes,forests play an important and indispensable role in adjusting the global carbon balance under climate change.Therefore,there are scientific and political implications in investigating the carbon budget of forest ecosystems and its response to climate change.Here we synthesized the most recent research progresses on the carbon cycle in terrestrial ecosystems,and applied an individual-based forest ecosystem carbon budget model for China(FORCCHN) to simulate the dynamics of the carbon fluxes of forest ecosystems in the northeastern China.The FORCCHN model was further improved and applied through adding variables and modules of precipitation(rainfall and snowfall) interception by tree crown,understory plants and litter.The results showed that the optimized FORCCHN model had a good performance in simulating the carbon budget of forest ecosystems in the northeastern China.From 1981 to 2002,the forests played a positive role in absorbing carbon dioxide.However,the capability of forest carbon sequestration had been gradually declining during the the same period.As for the average spatial distri-bution of net carbon budget,a majority of the regions were carbon sinks.Several scattered areas in the Heilongjiang Province and the Liaoning Province were identified as carbon sources.The net carbon budget was apparently more sensitive to an increase of air temperature than change of precipitation.

Estimated biomass carbon in thinned Cunninghamia lanceolate plantations at different stand-ages

Chinese fir(Cunninghamia lanceolate[Lamb.]Hook.)is a fast-growing species which is not only important as a timber-supplier,but also as an available sink for carbon(C)storage in biomass.Stand age and density are two critical factors that can determine tree C sequestration as interrelated drivers through natural self-thinning.C.lanceolate were planted using 1-year-old bare-root seedlings at the initial density of 1800 stems ha^(-1)in a 15-ha montane area of Hunan Province,China in 1987.The plantation was thinned twice 10 and 20 years after planting to leave trees of437.5±26.6,675.0±155.2 and 895.8±60.1 stems ha^(-1)as low,medium,and high densities,respectively.Tree height and diameter at breast height(DBH)were measured every2 years beginning from 23 years(2009)to 31 years(2018)after establishment,timber volume(TV)and biomass C were estimated accordingly.We did not find any interactive effect of age and density on any variables except for height.Both TV and biomass C increased with stand age or decreased in higher densities.The allometric heightDBH relationship can be fitted by an exponential risingto-maximum model with higher maximum value over time.The decline of biomass C along density fit with the inverse first-order polynomial model which indicated that at least1300-1500 stems ha^(-1)may be needed to maximize TV and biomass C for a longer term over 20 years.Therefore,to control the density to a reasonable level,over 1300 stems ha^(-1)in a rotation over 20 years old will be practical for tree biomass C in Chinese fir plantations.

Carbon storage and sequestration rate assessment and allometric model development in young teak plantations of tropical moist deciduous forest, India

Carbon （C） sequestration through plantations is one of the important mitigation measures for rising levels of carbon dioxide and other greenhouse gases in the atmosphere. This study aimed to assess C stocks and their sequestration rate, and to develop allometric models for estimation of C stocking in age-series young teak （Tectona grandis） planta- tions （1, 5, 11, 18, 24 and 30 years） by using biomass and productivity estimation and regression, respectively. These plantations were raised in tropical moist deciduous forests of Kumaun Himalayan tarai. Total C stocks estimated for these plantations were 1.6, 15.8, 35.4, 39.0, 61.5 and 73.2 Mg ha-1, respectively. Aboveground and belowground C storage in- creased with increasing plantation age; however, the range of their percentage contribution showed little variation （87.8-88.2 and 11.7-12.7 %, respectively）, The rate of C sequestration for these respective plantations was 1.06, 6.95, 5.46, 5.42, 3.39 and 5.37 Mg ha-1 a-1. Forty percent of the aboveground annual storage was retained in the tree while 60 % was released in the form of foliage, twigs, and fruit litter. In the case of total （tree） annual production, 43 % was retained while 57 % was released as litter including root. C stock, C sequestration rate, accumulation ratio （1.4-18.1）, root：shoot C ratio （0.61--0.13） and production efficiency （0.01-0.18） were comparable to some previous reports for other species and forests. These data could be useful in deciding the harvesting age for young teak with respect to C storage and sequestrationrate. Four allometric models using linear regression equations were developed between biomass （twice the C stock） and diameter, girth, and height of the tree at different ages. The diameter model was found more suitable for C stock predic- tion in similar areas.

Carbon stock and rate of carbon sequestration in Dipterocarpus forests of Manipur,Northeast India

We examined the carbon stock and rate of carbon sequestration in a tropical deciduous forest dominated by Dipterocarpus tuberculatus in Manipur,North East India.Estimation of aboveground biomass was determined by harvest method and multiplied with density of tree species.The aboveground biomass was between18.27–21.922 t ha-1and the carbon stock ranged from9.13 to 10.96 t C ha-1across forest stands.Aboveground biomass and carbon stock increased with the increase in tree girth.The rate of carbon sequestration varied from1.4722 to 4.64136 t ha-1year-1among the dominant tree species in forest stands in tropical deciduous forest area.The rate of carbon sequestration depends on species composition,the density of large trees in different girth classes,and anthropogenic disturbances in the present forest ecosystem.Further work is required to identify tree species having the highest potential to sequester CO2 from the atmosphere,which could lead to recommendations for tree plantations in a degraded ecosystem.

The Variability of Air-sea O_(2)Flux in CMIP6:Implications for Estimating Terrestrial and Oceanic Carbon Sinks

The measurement of atmospheric O_(2)concentrations and related oxygen budget have been used to estimate terrestrial and oceanic carbon uptake.However,a discrepancy remains in assessments of O_(2)exchange between ocean and atmosphere(i.e.air-sea O_(2)flux),which is one of the major contributors to uncertainties in the O_(2)-based estimations of the carbon uptake.Here,we explore the variability of air-sea O_(2)flux with the use of outputs from Coupled Model Intercomparison Project phase 6(CMIP6).The simulated air-sea O_(2)flux exhibits an obvious warming-induced upward trend(~1.49 Tmol yr−2)since the mid-1980s,accompanied by a strong decadal variability dominated by oceanic climate modes.We subsequently revise the O_(2)-based carbon uptakes in response to this changing air-sea O_(2)flux.Our results show that,for the 1990−2000 period,the averaged net ocean and land sinks are 2.10±0.43 and 1.14±0.52 GtC yr−1 respectively,overall consistent with estimates derived by the Global Carbon Project(GCP).An enhanced carbon uptake is found in both land and ocean after year 2000,reflecting the modification of carbon cycle under human activities.Results derived from CMIP5 simulations also investigated in the study allow for comparisons from which we can see the vital importance of oxygen dataset on carbon uptake estimations.

Sensitivity analysis of the De Nitrification and De Composition model for simulating regional carbon budget at the wetlandgrassland area on the Zoige Plateau,China

Although mathematical models(e.g., De Nitrification and De Composition(DNDC) provide a powerful tool to study regional carbon budget, it is still difficult to obtain accurate simulation results because there exists large uncertainties in modeling regional carbon budget. Through the investigation on the sensitivity of model output parameters to the input parameters, sensitivity analysis(SA) has been proved to be able to identify the key sources of uncertainties and be helpful to reduce the model uncertainties. However, some input parameters with discrete values(e.g., land use type and soil type) and the regional effect of the sensitive parameters were rarely examined in SA. In this paper, taking the Zoige Plateau as a case area, we combined the one-factor-ata-time(OAT) with Extended Fourier Amplitude Sensitivity Test(EFAST) to conduct a SA of DNDC for simulating the regional carbon budget, including Gross Primary Productivity(GPP), Net Primary Productivity(NPP), Net Ecosystem Productivity(NEP), autotrophic respiration(Ra), soil microbial heterotrophic respiration(Rh) and ecosystem respiration(Re). The result showed that the combination of OAT and EFAST could test the contribution of the input parameters with discrete values to the output parameters. In DNDC model, land use type and soil type had a significant impact on the regional carbon budget of the Zoige Plateau, and daily temperature was also confirmed to be one of the most important parameters for carbon budget. For the other input parameters, with the change of land use type or soil type at regional scale, the sensitive parameters of carbon budget would vary accordingly. The SA results would provide scientific evidence to optimize DNDC model and they suggested that we should pay attention to the spatial/temporal effect of SA and try to use the appropriate data in simulation of the regional carbon budget.

Carbon and nitrogen budget in fish-polychaete integrated aquaculture system

Integrated multi-tropic aquaculture(IMTA)systems have been used in China for many years and have achieved significant economic,social,and ecological benefits.However,there is still a lack of benthic bioremediation species that can effectively utilize the aquaculture particulate organic waste in the system.Polychaete Perinereis aibuhitensis Grube is used as an environmental remediation species for large-scale aquaculture to reduce particulate organic waste,which is of great significance to environmental protection.To improve bio-elements utilization efficiency,P.aibuhitensis was applied for IMTA indoor fish(Hexagrammos otakii)farming.Results showed that in the system,production of 1 kg of the fish discharged 2141-2338 mg of carbon and 529-532 mg of nitrogen,while in the monoculture of the fish,the figures were 3033-3390 mg and 764-794 mg,or 24.84%-35.26%and 30.35%-33.32%less,respectively.This approach promoted IMTA technology that could utilize the particulate organic waste from intensive aquaculture and reduce the adverse environmental effects.

Modeling Carbon and Water Budgets in the Lushi Basin with Biome-BGC

In this article, annual evapotranspiration(ET) and net primary productivity (NPP) of fourtypes of vegetation were estimated for the Lushi basin,a subbasin of the Yellow River in China. These fourvegetation types include: deciduous broadleaf forest,evergreen needle leaf forest, dwarf shrub and grass.Biome-BGC--a biogeochemical process model wasused to calculate annual ET and NPP for eachvegetation type in the study area from 1954 to 2000.Daily microclimate data of 47 years monitored byLushi meteorological station was extrapolated tocover the basin using MT-CLIM, a mountainmicroclimate simulator. The output files of MT-CLIM were used to feed Biome-BGC. We usedaverage ecophysiological values of each type ofvegetation supplied by Numerical TerradynamicSimulation Group (NTSG) in the University ofMontana as input ecophysiological constants file.The estimates of daily NPP in early July and annualET on these four biome groups were comparedrespectively with field measurements and other studies.Daily gross primary production (GPP) of evergreenneedle leaf forest measurements were very close tothe output of Biome-BGC, but measurements ofbroadleaf forest and dwarf shrub were much smallerthan the simulation result. Simulated annual ET andNPP had a significant correlation with precipitation,indicating precipitation is the major environmentalfactor affecting ET and NPP in the study area.Precipitation also is the key climatic factor for theinterannual ET and NPP variations.

Study on Soil Respiration Characteristics and Carbon Balance of <i>Kobresia pygmaea</i>Meadow in Qinghai-Tibet Plateau, China

Although soil respiration is the largest contributor to C flux from terrestrial ecosystems to the atmosphere, our understanding of its characteristics and carbon budget in alpine meadow is rather limited because of extremely geographic situation. This study was designed to examine soil CO2 efflux characteristics of diurnal and seasonal variation, thus obtaining estimates of carbon balance of Kobresia pygmaea meadow in Qinghai-Tibet plateau. The results showed that the soil respiration of diurnal and seasonal rate changed little in growing season and was mainly affected by temperature, and single peak curve that showed afternoon appeared. Composite model which was set by soil respiration rate, soil moisture content and temperature (atmospheric temperature and soil temperature) could explain better the variations of soil respiration rate. The variation range of Q10 ranged from 1.28 to 2.34, which was sensitive to temperature in green-up period and late growth stage, and decreased in growth peak period. Meanwhile, during the growing seasons the observed amount of annual carbon fixation via primary production for Kobresia pygmaea meadow ecosystem was about 120.21 g C·m-2·a-1. The carbon dioxide output via soil heterotrophic respiration was about 37.54 g C·m-2·a-1. So carbon budget had more input than output. The Kobresia pygmaea meadow ecosystem has stronger potential to absorb carbon dioxide, it was a sink of atmospheric CO2, and the plant community had a net carbon gain of 82.67 g C·m-2·a-1.

Bridging mapping and simulation modelling in the ecosystem service assessments of boreal forests:effects of bioenergy production on carbon dynamics

Background:Increasing the use of forest harvest residues for bioenergy production reduces greenhouse emissions from the use of fossil fuels.However,it may also reduce carbon stocks and habitats for deadwood dependent species.Consequently,simple tools for assessing the trade-offs of alternative management practices on forest dynamics and their services to people are needed.The objectives of this study were to combine mapping and simulation modelling to investigate the effects of forest management on ecosystem services related to carbon cycle in the case of bioenergy production;and to evaluate the suitability of this approach for assessing ecosystem services at the landscape level.Stand level simulations of forest growth and carbon budget were combined with extensive multi-source forest inventory data across a southern boreal landscape in Finland.Stochastic changes in the stand age class distribution over the study region were simulated to mimic variation in management regimes.Results:The mapping framework produced reasonable estimates of the effects of forest management on a set of key ecosystem service indicators:the annual carbon stocks and fluxes of forest biomass and soil,timber and energy-wood production and the coarse woody litter production over a simulation period 2012–2100.Regular harvesting,affecting the stand age class distribution,was a key driver of the carbon stock changes at a landscape level.Extracting forest harvest residues in the final felling caused carbon loss from litter and soil,particularly with combined aboveground residue and stump harvesting.It also reduced the annual coarse woody litter production,demonstrating negative impacts on deadwood abundance and,consequently,forest biodiversity.Conclusions:The refined mapping framework was suitable for assessing ecosystem services at the landscape level.The procedure contributes to bridging the gap between ecosystem service mapping and detailed simulation modelling in boreal forests.It allows for visualizing ecosystem services as fine resolution maps to support sustainable land use planning.In the future,more detailed models and a wider variety of ecosystem service indicators could be added to develop the method.

FOOD SOURCES AND CARBON BUDGET OF CHINESE PRAWN PENAEUS CHINENSIS

This study deals with contribution of artificial food pellet and natural food to Chinese prawn (Penaeus orientalis) growth in a semi-intensive culture pond. The prawn carbon consumption, budget, and the effects of some factors on the budget were investigated. The results showed that 26.2% of P. orientalis growth carbon came from formulated feed at the initial culture stage (when the prawns were 0.06±0.01 g in wet weight), and was 62.5% when the prawns were 9.56±1.04 g. The remaining part of the growth carbon was derived from organic fertilizer and natural food. The highest growth rate occurred at 20×10 -3 salinity. Suitable salinity for culturing Chinese prawn was (20-28)×10 -3 .

Carbon Budget for Basic Needs:Implications of International Equity and Sustainability

The fundamental way of satisfying the basic needs of human development is to secure the basic needs,limit luxurious and wasteful emissions,and ensure the fulfillment of climate targets,so as to achieve intra-and intergenerational equity.In this paper,the author discusses and analyzes a series of challenges that the development has to face,such as poverty elimination,urbanization,and industrialization,and the problems of increased consumption that is brought about by the improvement of living standards;the author distinguishes the stock emission,which does not need annual updating,and the flow emission of regular consumption;the author also defines the standards of energy consumption and carbon emissions that can meet the basic needs.On this basis,the author proposes the concept and method of carbon budget,compares this method with other means,and in particular,studies and analyzes the implications of international equity and sustainability of carbon budget as part of the international climate regime design.

Carbon Budget Proposal:An Institutional Framework for an Equitable and Sustainable World Climate Regime

Consensus on reducing greenhouse gas emissions has been reached at the technical and political level.However,as the issue involves economic costs and the right to develop,the international institutional framework for addressing greenhouse gas emissions has consistently failed to balance the demands of impartiality and sustainability.However,a sustainable carbon budget proposal is undoubtedly achievable if the global carbon budget (the total amount of carbon permitted by climate security) is made an absolute constraint.If a preliminary distribution was made among the world's population on a per capita basis,the total limited global carbon budget could not only meet basic needs but also ensure the proposal's equitable.Taking into account historical emission levels and future needs,we should carry out carbon budget transfer payments and devise a corresponding funding mechanism to ensure efficient allocation under the proposal.Unlike the phase-by-phase progress and provisional goals of the Kyoto Protocol,the carbon budget proposal outlined above is a comprehensive and holistic package.Due to the politicization of the climate change issue,however,many technical issues can only be worked out through international political and diplomatic negotiations.

The experimental studies on the carbon and nitrogen budgets of Pseudeuphausia sinica

The carbon and nitrogen budgets were estimated on the adult females, juveniles and post-furcilia larvae of Pseudeuphausia sinica fed on newly hatching nauplii of Artemia salina in the laboratory. It was found that the ingestion rate was linearly related to the food concentration, suggesting high feeding potential. The linear correlation could be established between the respirating rate (carbon consumption rate) and carbon ingestion rate, as well as carbon assimilation rate. The regression coefficients (i.e.specific dynamic action coefficients) were in the range from 9% to 16% (ingested C) or 10% to 17% (assimilated C) respectively, with lower in the post-furcilia larvae. There also existed a linear correlation equation between estimated total nitrogen excretion rate and the rates of nitrogen ingestion and assimilation separately, except for the juveniles. The defecation rates increased with the increase of the ingestion rate; as a result, assimilation efficiency was not related to the ingestion rate, ranging from 0.84 to 0.95. The results inducated that the nitrogen content in food particles was a key factor limiting the growth of P. sinica. The critical ingestion rate was 10 μgN·mg-1 body dry weight per day. Assimilated N was lost mostly by excretion, following allocated to somatic growth. The nitrogen loss by moult only accounted for a minor part. As for carbon budget, respiration and somatic growth also accounted for most of assimilation, but varied with ingestion rates. Moult loss was minor. Estimated reproductive growth (C&N) in the adult females accounted for somewhat higher percent of assimilation than the moult growth. The net growth efficiency (K2) increased with the increase of the ingestion rates, but decreased slightly for juvenile and post-furcilia larvae after the rates up to a certain value.

Studies on carbon budget score remarkable progress

On 23 November, 2006, a key CAS research project on carbon budget passed the review by a panel of experts under the joint

Carbon Budget Pattern and Carbon Compensation Standard of Xinjiang Tianshan World Natural Heritage Site

Clarifying the pattern of regional carbon balance and determining the carbon compensation standards ofstakeholders are the keys to building a regional carbon compensation mechanism and promoting regional carbonneutrality.The land use area of the Xinjiang Tianshan World Natural Heritage Site in 1980,2000,2010,and 2020was interpreted using remote sensing technology(RS)and geographic information system(GIS),and the netecosystem productivity model was used to calculate the carbon sink of the forest,grassland,water area,and cultivated land ecosystem in the heritage site.The IPCC carbon emission factor method and carbon footprint methodwere used to calculate the tourism and animal husbandry carbon emissions,and the carbon sink evolution characteristics,carbon emission structure characteristics,and carbon budget pattern of the heritage sites were analyzed.Further,the carbon compensation for tourists in the heritage site was calculated using the carbon compensation coefficient correction model and the tourists’willingness to pay method.The results demonstrated that(1)thecarbon sinks of the heritage sites decreased from 1980 to 2020,with those of grassland,cultivated land,forest land,and wetland exhibiting different degrees of decline.(2)The whole heritage site had a carbon deficit of 8.67×10^(6)tCO_(2).Tourism carbon emission was the main carbon source,accounting for more than 95%,whereas livestockcarbon emissions accounted for only 4.12%.The carbon emission intensity of regional human activities exceededits ecological carbon sink carrying capacity,and tourists were the main carbon compensators in heritage sites.(3)The theoretical compensation of tourists in the heritage site was 25.23 yuan p^(-1)yr^(-1),and the willingness to compensate was 14.78 yuan p^(-1)yr^(-1)(nonparametric estimation)and 5.93 yuan p^(-1)yr^(-1)(parametric estimation).Further,the standards for carbon compensation by tourists calculated using the two methods differed.Therefore,whenformulating the carbon compensation standards for stakeholders,the responsibility weight of the compensationsubject should be clarified,and the regional carbon balance and the willingness to pay of the compensation subjectshould be comprehensively considered.By adopting scientific and reasonable carbon compensation standards,carbon compensation mechanisms in the region can be effectively implemented.

Findings through the AsiaFlux network and a view toward the future

The preliminary results of long-term CO_(2)flux measurements at forest sites in East Asia are explained and compared with each other.The features of seasonal variation of CO_(2)fluxes are different among deciduous-broadleaf,evergreen-coniferous,deciduous-coniferous and tropical forests in East Asia,and the causes of difference are discussed.The integrated yearly NEP(net ecosystem production)estimated from the CO_(2)flux by eddy covariance method in various forests of East Asia has a notable difference in the range of 2 to 8 tC ha^(-1)yr^(-1).The main factors of this difference are the annual mean temperature and tree species.Furthermore,the remaining issues are discussed,such as the quantitative estimation of the CO_(2)flux by the eddy covariance method and the synthetic analysis of the carbon budget under collaborations with biological survey.