An assessment of uncertainty in forest carbon budget projections

Estimates of uncertainty are presented for projections of forest carbon inventory and average annual net carbon flux on private timberland in the US using the model FORCARB. Uncertainty in carbon inventory was approximately ±9% (2000 million metric tons) of the estimated median in the year 2000, rising to 11% (2800 million metric tons) in projection year 2040, with this range covering 95% of the distribution. Relative uncertainties about net flux were higher and more variable than relative uncertainty estimates of carbon inventory. Results indicated that relatively high correlations among projected carbon budgets for the regional forest types led to greater total uncertainty than under assumptions of independence among types, indicating that an accurate portrayal of correlations is important. Uncertainty in soil carbon, closely followed by uncertainty in tree carbon, were most influential in estimating uncertainty in carbon inventory, but uncertainties in projections of volume growth and volume removals were most important in estimating uncertainty in carbon flux. This implies the most effective ways of reducing uncertainty in carbon flux are different from those required to reduce uncertainties in carbon inventory. Analyses as presented here are necessary prerequisites to identify and reduce uncertainty in a systematic and iterative way.     

Carbon budget of the Canadian forest product sector

Although many factors influencing the forest C cycle are beyond direct human control, decisions made in forestry and the forest product sector (FPS) can either mitigate or aggravate the net C balance of terrestrial ecosystems. The Canadian Budget Model of the Forest Product Sector (CBM-FPS) described here, was designed to work with a national scale model of forest ecosystem dynamics (the Carbon Budget Model of the Canadian Forest Sector, CBM-CFS). The CBM-FPS accounts for harvested forest biomass C from the time that it enters the manufacturing process until it is released into the atmosphere. It also accounts for the use and production of energy by the FPS, and emission of CO₂ during FPS processing. The CBM-FPS accounting framework uses the characteristics of different forest product types to estimate changes in the storage of C in forest products; it tracks C from the transportation of the harvested raw material through various processing steps in sawmills or pulp mills, to its final destination (product, pulp, landfill, atmosphere or recycled). Because not all harvested biomass C is released into the atmosphere in the year it is harvested, the model tracks C retained in various short- and long-lived products, and in landfills. Model results are in general agreement with available data from 1920–1989. Average changes in net C stocks in the FPS, estimated as the difference between harvest C input to the FPS and total losses from the forest product sector is estimated to be 23.5 Tg C yr⁻¹ for the 1985–1989 period. The total FPS pool size at the end of this period is estimated to be 837 Tg C, of which only a fraction (32%) is retained in Canada. The total FPS C stock is small compared to that in the forest ecosystems from which they derive (estimated to contain 86 Pg C in 1989). Nevertheless, the changes in these C stocks contribute significantly to a reduction of the total net atmospheric exchange of the total forest sector (ecosystem and product sector) for that period.     

The carbon budget of California

The carbon budget of a region can be defined as the sum of annual fluxes of carbon dioxide (CO₂) and methane (CH₄) greenhouse gases (GHGs) into and out of the regional surface coverage area. According to the state government's recent inventory, California's carbon budget is presently dominated by 115 MMTCE per year in fossil fuel emissions of CO₂ (>85% of total annual GHG emissions) to meet energy and transportation requirements. Other notable (non-ecosystem) sources of carbon GHG emissions in 2004 were from cement- and lime-making industries (7%), livestock-based agriculture (5%), and waste treatment activities (2%). The NASA-CASA (Carnegie Ames Stanford Approach) simulation model based on satellite observations of monthly vegetation cover (including those from the Moderate Resolution Imaging Spectroradiometer, MODIS) was used to estimate net ecosystem fluxes and vegetation biomass production over the period 1990–2004. California's annual NPP for all ecosystems in the early 2000s (estimated by CASA at 120 MMTCE per year) was roughly equivalent to its annual fossil fuel emission rates for carbon. However, since natural ecosystems can accumulate only a small fraction of this annual NPP total in long-term storage pools, the net ecosystem sink flux for atmospheric carbon across the state was estimated at a maximum rate of about 24 MMTCE per year under favorable precipitation conditions. Under less favorable precipitation conditions, such as those experienced during the early 1990s, ecosystems statewide were estimated to have lost nearly 15 MMTCE per year to the atmosphere. Considering the large amounts of carbon estimated by CASA to be stored in forests, shrublands, and rangelands across the state, the importance of protection of the natural NPP capacity of California ecosystems cannot be overemphasized.     

正确评价森林水文效应

只有正确客观地认识森林水文效应，才能在实践中实现其指导意义。论文从森林与水的关系入手，提出要确立系统观。以我国各生态定位研究站及其他同类研究项目的多年研究结果为基础，系统客观地分析和阐述了森林生态系统与水分循环的关系以及森林在各方面的综合调节功能。提出在西部开发中林草植被建设要考虑到水资源的科学分配；要在保证生态安全的前提下，所有产业“适度发展”。     

基于涡度相关技术的农田生态系统碳收支评估

以涡度相关技术为主要观测手段,连续观测冬小麦和水稻生态系统主要生长季净生态系统CO₂交换（NEE）的变化规律,评估两种农田生态系统CO₂的源/汇功能.结果表明,整个观测期间,两种作物生态系统CO₂浓度的日变化曲线呈现白天低、晚上高的"一峰一谷"型,冬小麦生态系统变化较为平缓,而水稻生态系统变化则比较剧烈.冬小麦和水稻生态系统白天30 min CO₂通量的平均值分别为-13.4 μmol·m^-2·s^-1和-12.9 μmol·m^-2·s^-1,通量最高值分别出现冬小麦的孕穗期与水稻的开花期.此外,两种作物生长季CO₂通量表现出"U"形曲线的日变化特点,白天以吸收CO₂为主,冬小麦和水稻生态系统分别于12：00和11：30达到吸收峰值;夜间CO₂通量变化较为稳定,表现为呼吸排放CO₂.两种农田生态系统均表现为碳汇,冬小麦与水稻生态系统净碳交换分别为188.2 g·m^-2与233.8 g·m^-2.     

基于RDBMS的海洋溢油生物资源损害评估空间数据库研究

为满足海洋溢油生物资源损害评估数据管理和共享的应用需求,提出构建基于关系数据库(RDBMS)的空间数据库.通过分析电子海图和评估模型数据中的矢量、栅格、时空等空间数据类型及其特征,探讨了RDBMS支持下的空间数据组织、压缩存储、维护管理的实现方法,并建立了基于空间数据库引擎的空间数据访问模式.应用实例表明,基于RDBM...     

A distributional analysis of the socio-ecological and economic determinants of forest carbon stocks

Forest carbon (C) sequestration is being actively considered by several states as a way to cost-effectively comply with the forthcoming United States (US) Environmental Protection Agency’s rule that will reduce power plant C emissions by 32% of 2005 levels by 2030. However, little is known about the socio-ecological and distributional effects of such a policy. Given that C is heterogeneous across the landscape, understanding how social, economic, and ecological changes affect forest C stocks and sequestration is key for developing forest management policies that offset C emissions. Using Florida US as a case study, we use US National Forest Inventory Analysis and Census Bureau data in both linear regression and quantile regression analyses to examine the socio-ecological and economic determinants of forest C stocks and its relationship with differing communities. Quantile regression findings demonstrate nonlinearity in the effects of key determinants, which highlight the limitations of regularly used mean-based regression analyses. We also found that forest basal area, site quality, stand size, and stand age are significant ecological predictors of carbon stocks, with a positive and increasing effect on upper quantiles where C stocks are greater. The effect of education was generally positive and mostly significant at upper quantiles, while the effects of income and locations with predominantly minority residents (as compared to whites) were negative. Upper quantiles were also affected by population age. Our findings underscore the importance of considering the broader socio-ecological and economic implications of compliance strategies that target the management of forests for carbon sequestration and other ecosystem services.     

Transaction costs for carbon sequestration projects in the tropical forest sector

There is general consensus that carbon (C) sequestration projects in forests are a relatively low cost option for mitigating climate change, but most studies on the subject have assumed that transaction costs are negligible. The objectives of the study were to examine transaction costs for forest C sequestration projects and to determine the significance of the costs based on economic analyses. Here we examine four case studies of active C sequestration projects being implemented in tropical countries and developed for the C market. The results from the case studies were then used with a dynamic forest and land use economic model to investigate how transaction costs affect the efficiency and cost of forest C projects globally. In the case studies transaction costs ranged from 0.38 to 27 million US dollars ($0.09 to $7.71/t CO₂) or 0.3 to 270 % of anticipated income depending principally on the price of C and project size. The three largest cost categories were insurance (under the voluntary market; 41–89 % of total costs), monitoring (3–42 %) and regulatory approval (8–50 %). The global analysis indicated that most existing estimates of marginal costs of C sequestration are underestimated by up to 30 % because transaction costs were not included.     

Assessment of the nitrogen and carbon budget of two managed temperate grassland fields

Greenhouse gas budgets as well as the productivity of grassland systems are closely related to the carbon (C) and nitrogen (N) cycles. Within the framework of the CarboEurope and NitroEurope projects we have measured C and N exchange on the field scale at the grassland site Oensingen previously converted from arable rotation. The site is located on the Swiss Central Plateau and consists of two parallel fields of equal size. One field was subjected to intensive management with average nitrogen input of 230 kg-N ha⁻¹ year⁻¹ and 4–5 cuts per year, and the other to an extensive management with no fertilisation and less frequent cutting. The total C budget of the fields was assessed by measuring the CO₂ exchange by eddy covariance and analysing the carbon import by manure application and export by harvest. The N budget of the managed grassland is more complex. Besides the management related import and export, it includes gaseous exchange in many different forms (NO, NO₂, HNO₃, N₂O, NH₃, N₂) needing different analytical techniques, as well as input by rain and leaching of N-compounds with the soil water. The main (“level-3”) field sites in the NitroEurope project are supposed to measure 95% of the N fluxes at the field scale. For several of the N fluxes specific measurements have been performed for 1 year or longer at the site. Some of the remaining N budget components (dry and wet deposition) could be estimated from results of a national deposition network, while other components (NH₃ and N₂ emission) were estimated based on literature parameterisations. However, we found indications that the (systematic) uncertainties of these estimated N-fluxes are large and that it is important to make site-specific measurement for all relevant budget components. The suitability of corresponding experimental methods is discussed.Analysis of the C budget over a 6-year period (2002–2007) showed a significant mean difference between the two newly established grassland fields with a likely net carbon loss for the extensive management and a net sequestration for the intensive management. Since the C/N ratio of the soil organic matter of the grassland is constrained in a rather narrow range around 9.3, the change in the soil carbon pool is supposed to be accompanied by a corresponding change in the N storage. This approach provided an alternative method to check the N budget of the two grassland fields derived from the individual N fluxes.     

Achieving forest carbon information with higher certainty: A five-part plan

International negotiations on the inclusion of land use activities into an emissions reduction system for the UN Framework Convention on Climate Change (UNFCCC) have been partially hindered by the technical challenges of measuring, reporting, and verifying greenhouse gas (GHG) emissions and the policy issues of leakage, additionality, and permanence. This paper outlines a five-part plan for estimating forest carbon stocks and emissions with the accuracy and certainty needed to support a policy for Reducing Emissions from Deforestation and forest Degradation, forest conservation, sustainable management of forests, and enhancement of forest carbon stocks (the REDD-plus framework considered at the UNFCCC COP-15) in developing countries. The plan is aimed at UNFCCC non-Annex 1 developing countries, but the principles outlined are also applicable to developed (Annex 1) countries. The parts of the plan are: (1) Expand the number of national forest carbon Measuring, Reporting, and Verification (MRV) systems with a priority on tropical developing countries; (2) Implement continuous global forest carbon assessments through the network of national systems; (3) Achieve commitments from national space agencies for the necessary satellite data; (4) Establish agreed-on standards and independent verification processes to ensure robust reporting; and (5) Enhance coordination among international and multilateral organizations.     

功能区土地利用碳收支空间分异及碳补偿分区——以武汉城市圈为例

开展功能区土地利用碳收支评估并构建碳补偿分区优化框架,对于制定适应各功能区低碳策略、指导补偿额度流向、推动区域协调发展具有重要现实意义。以武汉城市圈县域为基本单元,在分析主体功能区划下土地利用碳收支空间分异特征的基础上,借助标准显示性比较优势指数法、SOM-K-means模型、二维关联矩阵等方法,对武汉城市圈进行了碳补偿类型区划分及优化。结果表明：武汉城市圈各县域土地利用碳排放总量地区差异显著,呈现“西高东低,中心最高”空间分布格局;主体功能区划下土地利用碳排放、碳吸收均具有明显空间分异特征,碳吸收与碳排放呈现出一定程度的相对空间分布趋势;武汉城市圈共有16个碳补偿支付区、11个碳补偿获补区以及12个碳补偿平衡区;结合主体功能区规划战略目标,最终形成7类碳补偿空间优化区,并对每一类型区提出了相应的低碳发展方向及策略。     

Assessing negative carbon dioxide emissions from the perspective of a national “fair share” of the remaining global carbon budget

We present an assessment of the plausible Paris-aligned fair share nett cumulative carbon dioxide (CO₂) quota for an example nation state, the Republic of Ireland. By Paris-aligned, we mean consistent with the Paris Agreement adopted at the 21st Conference of the Parties to the United Nations Framework Convention on Climate Change, at Paris, France, in December 2015 (UNFCCC 2015). We compare and contrast this quota with both the aspirations expressed in the current Irish National Policy Position and current national emission projections. The fair share quota is assessed as a maximum of c. 391 million tonnes of carbon dioxide (MtCO₂), equal to 83 tonnes of carbon dioxide (tCO₂) per capita, from 2015, based on a precautionary estimate of the global carbon budget (GCB) and specific interpretation of global equity. Given Ireland’s high current CO₂ per capita emission rate, this would correspond to sustained year-on-year reductions in nett annual CO₂ emissions of over ??11% per year (beginning as of 2016). By contrast, the CO₂ mitigation target indicated in the National Policy Position corresponds to nett annual reduction rates in the range of only ?4.7% per year (low ambition) up to a maximum of ??8.3% per year (high ambition), and projections based on current and immediately planned mitigation measures indicate the possibility, instead, of sustained increases in emissions at a rate of the order of +?0.7% per year. Accordingly, there is a large gap between Paris-aligned ambition and current political and policy reality on the ground, with a significant risk of early emergence of “CO₂ debt” and tacit reliance on rapid deployment of currently speculative (at a relevant scale and feasible cost) negative CO₂ emission technologies to actively remove CO₂ from the atmosphere. While the detailed policy situation will clearly differ from country to country, we suggest that this methodology, and its CO₂debt framing, may be usefully applied in other individual countries or regions. We recommend that such framing be incorporated explicitly into a global mitigation strategy via the statements of nationally determined contributions required to be submitted and updated by all parties under the Paris Agreement processes.

     

典型场地四氯化碳污染的健康风险评价

以华北某污染场地为研究区域,采集了场地内大气、土壤、地表水和地下水4个类别共196个样品.分析了25项挥发性有机物在不同区域的分布特征,探讨了超标污染物的污染来源,最后,应用美国环保局的健康风险评价方法,对场地超标污染物进行了健康风险评价.结果表明,场地超标污染物仅为四氯化碳;主要赋存于地下水中,其污染晕的平面分布与地...     

A virtual “field test” of forest management carbon offset protocols: the influence of accounting

Of the greenhouse gas (GHG) mitigation options available from U.S. forests and agricultural lands, forest management presents amongst the lowest cost and highest volume opportunities. A number of carbon (C) accounting schemes or protocols have recently emerged to track the mitigation achieved by individual forest management projects. Using 50-year C cycling data from the Calhoun Experimental Forest in South Carolina, USA, C storage is estimated for a hypothetical forest management C offset project operating under seven of these protocols. After 100 years of project implementation, net C sequestration among the seven protocols varies by nearly a full order of magnitude. This variation stems from differences in how individual C pools, baseline, leakage, certainty, and buffers are addressed under each protocol. This in turn translates to a wide variation in the C price required to match the net present value of the non-project, business-as-usual alternative. Collectively, these findings suggest that protocol-specific restrictions or requirements are likely to discount the amount of C that can be claimed in “real world” projects, potentially leading to higher project costs than estimated in previous aggregate national analyses.     

Forest carbon accounting methods and the consequences of forest bioenergy for national greenhouse gas emissions inventories

While bioenergy plays a key role in strategies for increasing renewable energy deployment, studies assessing greenhouse gas (GHG) emissions from forest bioenergy systems have identified a potential trade-off of the system with forest carbon stocks. Of particular importance to national GHG inventories is how trade-offs between forest carbon stocks and bioenergy production are accounted for within the Agriculture, Forestry and Other Land Use (AFOLU) sector under current and future international climate change mitigation agreements. Through a case study of electricity produced using wood pellets from harvested forest stands in Ontario, Canada, this study assesses the implications of forest carbon accounting approaches on net emissions attributable to pellets produced for domestic use or export. Particular emphasis is placed on the forest management reference level (FMRL) method, as it will be employed by most Annex I nations in the next Kyoto Protocol Commitment Period. While bioenergy production is found to reduce forest carbon sequestration, under the FMRL approach this trade-off may not be accounted for and thus not incur an accountable AFOLU-related emission, provided that total forest harvest remains at or below that defined under the FMRL baseline. In contrast, accounting for forest carbon trade-offs associated with harvest for bioenergy results in an increase in net GHG emissions (AFOLU and life cycle emissions) lasting 37 or 90 years (if displacing coal or natural gas combined cycle generation, respectively). AFOLU emissions calculated using the Gross-Net approach are dominated by legacy effects of past management and natural disturbance, indicating near-term net forest carbon increase but longer-term reduction in forest carbon stocks. Export of wood pellets to EU markets does not greatly affect the total life cycle GHG emissions of wood pellets. However, pellet exporting countries risk creating a considerable GHG emissions burden, as they are responsible for AFOLU and bioenergy production emissions but do not receive credit for pellets displacing fossil fuel-related GHG emissions. Countries producing bioenergy from forest biomass, whether for domestic use or for export, should carefully consider potential implications of alternate forest carbon accounting methods to ensure that potential bioenergy pathways can contribute to GHG emissions reduction targets.     

Influence of carbon sources on nutrient removal in A/O-MBRs: Availability assessment of internal carbon source

Both internal carbon source and some external carbon sources were used to improve the nutrient removal in Anaerobic-Anoxic-Oxic-Membrane Bioreactor (A²/O-MBRs), and their technical and cost analysis was investigated. The experimental results showed that the nutrient removals were improved by all the carbon source additions. The total nitrogen and phosphorus removal efficiency were higher in the experiments with external carbon source additions than that with internal carbon source addition. It was found that pathways of nitrogen and phosphorus transform were different dependent on different carbon source additions by the mass balance analysis. With external carbon source addition, the simultaneous nitrification and denitrification occurred in aerobic zone, and the P-uptake in aerobic phase was evident. Therefore, with addition of C-MHP (internal carbon source produced from sludge pretreatment by microwave-H₂O₂ process), the denitrification and phosphorus-uptake in anoxic zone was notable. Cost analysis showed that the unit nitrogen removal costs were 57.13 CNY/kg N of C-acetate addition and 54.48 CNY/kgN of C-MHP addition, respectively. The results indicated that the C-MHP has a good technical and economic feasibility to substitute external carbon sources partially for nutrient removal.     

向往森林

春天是万物复苏的季节，也是回归自然的绝佳时候。森林，那是一个接受大自然的洗礼、体验舂的气息的最佳去处。     

National forest policy as a platform for biosphere carbon management: the case of community forestry in Cameroon

Little attention has been given to the development of national policies relevant for the uptake, development and implementation of Clean Development Mechanism (CDM) projects. In this paper we examine the compatibility between forestry and related policy provisions in Cameroon and the CDM provisions for Land Use, Land Use Change and Forestry (LULUCF). For each CDM requirement such as eligibility, additionality, impact assessment and sustainable development, relevant national forestry policy questions are identified. These relevant policy questions are applied to community forestry policy instruments in Cameroon to analyse the likelihood that they can enhance or inhibit the uptake and implementation of biosphere carbon projects. We found that choosing a single crown cover value (from between 10 and 30%) presented a serious dilemma for Cameroon given its diverse vegetation cover. Adopting any single value within this range is unlikely to optimize national carbon management potential. The current forest institutional and regulatory policy framework in Cameroon is inadequate for promoting carbon forestry under current CDM rules. We conclude that national policy in Cameroon would need to recognise the need for and adopt a pro-active approach for biosphere carbon management, engaging in institutional development, integrated planning, project development support and providing adequate regulatory frameworks to enhance sustainable development through CDM projects. The need for CDM/Kyoto capacity building support for proactive national and local policy development is highlighted.     

Quantification of net primary production of Chinese forest ecosystems with spatial statistical approaches

Net primary production (NPP) of terrestrial ecosystems provides food, fiber, construction materials, and energy to humans. Its demand is likely to increase substantially in this century due to rising population and biofuel uses. Assessing national forest NPP is of importance to best use forest resources in China. To date, most estimates of NPP are based on process-based ecosystem modeling, forestry inventory, and satellite observations. There are little efforts in using spatial statistical approaches while large datasets of in-situ observed NPP are available for Chinese forest ecosystems. Here we use the surveyed forest NPP and ecological data at 1,266 sites, the data of satellite forest coverage, and the information of climate and topography to estimate Chinese forest NPP and their associated uncertainties with two geospatial statistical approaches. We estimate that the Chinese forest and woodland ecosystems have total NPP of 1,325 ± 102 and 1,258 ± 186 Tg C year⁻¹ in 1.57 million km² forests with a regression method and a kriging method, respectively. These estimates are higher than the satellite-based estimate of 1,034 Tg C year⁻¹ and almost double the estimate of 778 Tg C year⁻¹ using a process-based terrestrial ecosystem model. Cross-validation suggests that the estimates with the kriging method are more accurate. Our developed geospatial statistical models could be alternative tools to provide national-level NPP estimates to better use Chinese forest resources.     

中国森林生态安全空间关联的网络特征及其驱动机制

提高森林生态安全的整体水平,是生态文明建设和林业可持续发展的必然选择。在对2009—2018年中国省际森林生态安全进行定量测度的基础上,利用修正的引力模型计算省际间的空间关联关系,并运用社会网络分析法探究其网络特征及驱动机制。结果表明：（1）中国森林生态安全的空间关联网络整体具有较好的通达性和显著的等级性,但关联强度和稳定性较低。（2）中国森林生态安全空间关联网络呈现出明显的“中心—外围”格局,山东、河南、湖北、湖南等省份处于网络中心位置,发挥重要的中介作用。（3）中国森林生态安全的空间关联网络可划分为经纪人、净溢出、净受益、双向溢出四个板块,并呈现板块内集聚为主、板块间关联为辅的空间关联特征。（4）经济发展差异、林业产业结构差异、城镇化水平差异、林业生态建设投入差异、森林资源禀赋差异对中国森林生态安全空间关联网络的形成具有弱负向的驱动作用,地理邻接关系对其具有强正向的驱动作用。