CBM-CFS3: A model of carbon-dynamics in forestry and land-use change implementing IPCC standards

The scientific community, forest managers, environmental organizations, carbon-offset trading systems and policy-makers require tools to account for forest carbon stocks and carbon stock changes. In this paper we describe updates to the Carbon Budget Model of the Canadian Forest Sector (CBM-CFS3) implemented over the past years. This model of carbon-dynamics implements a Tier 3 approach of the Intergovernmental Panel on Climate Change (IPCC) Good Practice Guidance for reporting on carbon stocks and carbon stock changes resulting from Land Use, Land-use Change and Forestry (LULUCF). The CBM-CFS3 is a generic modelling framework that can be applied at the stand, landscape and national levels. The model provides a spatially referenced, hierarchical system for integrating datasets originating from different forest inventory and monitoring programs and includes a structure that allows for tracking of land areas by different land-use and land-use change classes. Ecosystem pools in CBM-CFS3 can be easily mapped to IPCC-defined pools and validated against field measurements. The model uses sophisticated algorithms for converting volume to biomass and explicitly simulates individual annual disturbance events (natural and anthropogenic). Several important scientific updates have been made to improve the representation of ecosystem structure and processes from previous versions of CBM-CFS. These include: (1) an expanded representation of dead organic matter and soil carbon, particularly standing dead trees, and a new algorithm for initializing these pools prior to simulation, (2) a change in the input data requirement for simulating growth from biomass to readily available merchantable volume curves, and new algorithms for converting volume to biomass, (3) improved prediction of belowground biomass, and (4) improved parameters for soil organic matter decay, fire, insect disturbances, and forest management. In addition, an operational-scale version of CBM-CFS3 is freely available and includes tools to import data in standard formats, including the output of several timber supply models that are commonly used in Canada. Although developed for Canadian forests, the flexible nature of the model has enabled it to be adapted for use in several other countries.     

Water budget and the consequent duration of canopy carbon gain in a teak plantation in a dry tropical region: Analysis using a soil–plant–air continuum multilayer model

A soil–plant–air continuum multilayer model was used to numerically simulate canopy net assimilation (A_n), evapotranspiration (ET), and soil moisture in a deciduous teak plantation in a dry tropical climate of northern Thailand to examine the influence of soil drought on A_n. The timings of leaf flush and the end of the canopy duration period (CDP) were also investigated from the perspective of the temporal positive carbon gain. Two numerical experiments with different seasonal patterns of leaf area index (LAI) were carried out using above-canopy hydrometeorological data as input data. The first experiment involved seasonally varying LAI estimated based on time-series of radiative transmittance through the canopy, and the second experiment applied an annually constant LAI. The first simulation captured the measured seasonal changes in soil surface moisture; the simulated transpiration agreed with seasonal changes in heat pulse velocity, corresponding to the water use of individual trees, and the simulated A_n became slightly negative. However, in the second simulation, A_n became negative in the dry season because the decline in stomatal conductance due to severe soil drought limited the assimilation, and the simultaneous increase in leaf temperature increased dark respiration. Thus, these experiments revealed that the leaflessness in the dry season is reasonable for carbon gain and emphasized the unfavorable soil water status for carbon gain in the dry season. Examining the duration of positive A_n (DPA) in the second simulation showed that the start of the longest DPA (LDPA) in a year approached the timing of leaf flush in the teak plantation after the spring equinox. On the other hand, the end appeared earlier than that of all CDPs. This result is consistent with the sap flow stopping earlier than the complete leaf fall, implying that the carbon assimilation period ends before the completion of defoliation. The model sensitivity analysis in the second simulation suggests that a smaller LAI and slower maximum rate of carboxylation likely extend the LDPA because soil water from the surface to rooting depth is maintained longer at levels adequate for carbon gain by decreased canopy transpiration. The experiments also suggest that lower soil hydraulic conductivity and deeper rooting depth can postpone the end of the LDPA by increasing soil water retention and the soil water capacity, respectively.     

基于能值理论的生态足迹方法改进

生态足迹方法自提出以来受到广泛关注,其缺点也受到一些学者的批评。ZhaoSheng等2005年提出能值足迹法,弥补了生态足迹法以土地生产能力为限制的缺点。论文提出区域能值足迹法,以弥补其改进方法不能够反映区域实际情况和技术进步带来影响的不足。最后,以岷江上游1982到2002年为例应用3种方法进行计算分析。结果表明研究区生态足迹呈缓慢上升趋势,生态足迹方法计算结果<能值足迹<区域能值足迹;生态承载力计算结果显示生态足迹与区域能值足迹方法结果呈平缓下降趋势,而能值足迹方法结果呈不规则变动。区域能值足迹法能够考虑到区域实际情况和技术进步,但它不能完全代替生态足迹方法,将其结合应用将得到更多信息。     

The calculation of equivalence factor for ecological footprints in China: a methodological note

The Ecological Footprint (EF), a physical indicator to measure the extent of humanity’s use of natural resources, has gained much attention since it was first used by Wackernagel and Rees in 1996. In order to appraise land area types with different levels of productivity, they introduced the concept of an equivalence factor. This relates to the average primary biomass productivities of different types of land (i.e. arable land, pasture, forest, water/fishery, built-up land and fossil energy land) to the regional average primary biomass productivity of all land types in a given year. Hence, the equivalence factor is an important parameter in the EF model and it directly affects the reliability of all results. Thus, this article calculates equivalence factors on the national and provincial levels in China based on Net Primary Production (NPP) from MODIS 1 km data in 2008. Firstly, based on the Light Utility Efficiency and CASA model, the NPP of different biologically productive lands of China and of different provinces was calculated. Secondly, China’s equivalence factor for 6 land area types was calculated based on NPP: arable land and built-up land has an equivalence factor of 1.71, forest and fossil energy land has a factor of 1.41, pasture has a factor of 0.44 and water/fishery 0.35; Finally, the equivalence factor of 6 land area types in different provinces was also calculated. The NPP of each ecosystem type varies along with the equivalence factor in different provinces. However, the ranking of the equivalence factors in different provinces remain the same, with that of arable land being the largest, and the water/fishery being the smallest.     

Seasonal Changes in Soil Atmospheric Co2 Concentrations in Two Upland Catchments and Associated Changes in River Water Chemistry

Seasonal changes in river water chemistry and in soil atmospheric CO₂ concentrations at two depths and drainage water solute composition at two upland peaty podzol sites in north east Scotland were monitored over 12 months. the CO₂ concentrations were controlled by changes in soil temperature and moisture status. Highest CO₂ concentrations were observed in late summer 1988 when both soil temperatures and the moisture status of the soils were high. Then maximum CO₂ concentrations of 4% (v/v) were recorded for one of the sites. No significant correlations between seasonal changes in soil CO₂ concentrations and river water solute composition were observed. Nevertheless the field results and laboratory experiments indicated that in upland areas, where soils with acid surface horizons are common, soil CO₂ substantially influences river water chemistry at baseflow, increasing the pH and cation concentration of the soil water draining into the river. the results suggest that transfer of carbon as dissolved CO₂ in drainage water is a significant pathway for CO₂ transfer to the atmosphere.     

基于ARIMA模型的辽河流域生态足迹动态模拟与预测

将能值与生态足迹理论相结合,引入能量折算系数,通过能值密度构建能值-生态足迹模型,并应用此模型对辽河流域2001—2010年生态承载力和生态足迹进行计算。生态承载力计算主要是自然生态承载力和本地产品产出承载力,其中自然生态承载力主要考虑可更新资源的承载力,本地产品产出承载力主要包括生物资源产出承载力和工业产品产出承载力。生态足迹的计算主要包括消费足迹和污染足迹,消费足迹主要测算生物资源消费、能源消费和水资源消费足迹。污染足迹主要测算废气和生活废水、工业废水对自然生态系统带来的负荷。测算结果表明:2001—2010年辽河流域人均生态承载力和人均生态足迹均有所增加,但是生态足迹的增长速度远远大于生态承载力,致使流域内自2001与2009年生态略有盈余外,其余年份均出现生态赤字,处于不可持续发展状态。以能值-生态足迹模型测算结果为基础,基于EViews采用自回归综合移动平均模型(ARIMA),对流域内10年的生态足迹和生态承载力进行动态模拟。首先通过ADF与PP单位根检验时间序列的平稳性;其次分析序列的自相关函数图和偏自相关函数,初步确定AR和MA的阶次;再根据R2、AIC及SC准则,进行模型参数估计并诊断分析;最后确定最佳模拟模型。以ARIMA模型预测2011—2015年辽河流域生态足迹和生态承载力的演变趋势。预测结果表明,人均生态足迹在未来5年内会继续呈直线式增长,到2015年达到7.387 8 hm2,是2001年的2.16倍;而人均生态承载力在2011年之后开始下降,生态赤字继续扩大,到2015年增长到-4.167 67,约为2005年的10倍,流域内不可持续发展形势会更加恶化。最后提出辽河流域生态安全建设的对策。能值-生态足迹模型测算结果与实地调研基本相符,较真实反映了辽河流域可持续发展状况。基于ARIMA模型模拟预测结果可为未来流域开发和建设提供参考依据。     

基于ESDA的中国省际水足迹强度的空间关联格局分析

水足迹强度是一个反映水的利用效率的指标,论文在对1995-2009年中国31个省(市、区)水足迹计算的基础上(因资料所限,未考虑香港、澳门和台湾地区),利用探索性空间数据分析(ESDA)对15 a来各地区水足迹强度空间分布格局以及演变态势进行了分析和探讨。结果表明:①中国水足迹强度整体呈现明显的下降趋势,说明水资源的利用效率明显提高,但是区域发展并不平衡;②从全局空间分异来看,中国各地区水足迹强度呈现出正的空间相关性特征,存在着空间集聚特征,即水足迹强度高的地区相互邻接,强度低的地区相互邻接;③从局部空间分异来看,空间正相关模式(LL集聚和HH集聚)所占比例很大,且在研究年份内逐渐增加,反映出水足迹强度的LL集聚和HH集聚变得越来越显著。LL集聚主要分布在东部沿海一带,在空间上有明显的向周边扩散的趋势;HH集聚主要分布在西部地区,在空间分布上较稳定。     

Development of a theoretical framework for the evaluation of risk connected to accidental oxygen releases

A short-cut methodology for a fast estimation of hazards from oxygen releases and the evaluation of safety distances is presented. Starting from a historical survey on accidents involving oxygen releases and consequent scenarios, the approach includes analytical models for the quantification of incremental hazards due to oxygen releases, in non-obstructed areas, both for continuous and nearly instantaneous scenarios, adopting a simple Gaussian dispersion model. An example of the application of the model in a real case-study and relevant quantitative results are presented.     

The influence of impurities on the transportation safety of an anthropogenic CO2 pipeline

Transportation safety is a key aspect of carbon capture and storage (CCS), which is a major technology used to reduce greenhouse gas emissions. Supercritical CO₂ pipelines have been certified as an optimised choice for CO₂ transportation. The results of this study show that the Peng–Robinson (PR) equation of state is recommended for analysis of the properties of supercritical CO₂. The influence of nonpolar and polar impurities on the two-phase region and the location of the sharp discontinuity in the density are found by analysing the ternary phase equilibrium and physical parameters using the PR equation of state. A transitional area between the supercritical phase and the dense phase, where the density changes abruptly, is defined as the quasi-critical region. This study describes the functional relation between the temperature and the pressure that defines the quasi-critical line by calculating the partial derivative equations and then determines the effect of impurities on the quasi-critical region of transported CO₂. Operational recommendations for pipeline transportation of flue CO₂ are developed using a pipeline operated by Sinopec as an example, demonstrating the influence of impurities in flue CO₂ on saturation pressure for control and prevention of fractures in CO₂ pipelines.     

纺织印染企业水足迹测算案例

企业水足迹可用于节水减排效果的评价. 企业蓝水足迹指企业对传统水源的消耗,绿水足迹指企业收集处理并用于生产等目的的降水量;灰水足迹指以自然本底浓度和环境水质标准为基准,将企业产生的污染物负荷吸收同化所需的淡水量. 概化了企业用、排水模型,并基于《水足迹评价手册》建立了企业水足迹测算方法,测算了企业蓝水足迹、绿水足迹和灰水足迹,以及节水减排措施对削减水足迹的贡献率. 根据该测算方法对某纺织印染企业开展了案例研究. 结果表明:①经过清洁生产审核,某纺织印染企业的单位产品产量蓝水足迹为171 t/t,削减了26.3%;单位产品产量灰水足迹为146 t/t,削减了31.1%;而由于降水的采用,单位产品产量绿水足迹由0 t/t增至8 t/t;②在节水减排贡献方面,水回用措施显著大于工艺节水措施,节水和水回用措施分别削减蓝水足迹1.77×104和48.60×104 t,二者分别削减灰水足迹1.60×104和57.80×104 t.