森林生态系统粗死木质残体碳储量研究进展

粗死木质残体(CWD)是森林生态系统重要的结构性与功能性单元,作为连接植被碳库与土壤碳库的关键纽带,对全球森林生态系统碳循环发挥着重要而独特的作用,越来越多的学者开始关注CWD碳储量相关研究。系统阐述了国内外CWD碳储量研究的发展历程、研究范围与基本特征等内容,总结概括了CWD体积测算、CWD碳浓度估算等碳计量相关方法的研究进展。通过梳理发现:国内外学者对CWD碳储量的研究仍处于初级阶段,主要集中于探讨不同树种、不同林龄、不同腐解等级、不同海拔、不同存在形式的森林CWD碳储量分布特征,而较少关注CWD碳库对土壤碳库和植被碳库的作用机制以及对未来气候变化的响应和反馈机制;CWD碳计量方法较为单一,普遍采用的是传统的"生物量-碳浓度法",而运用机器学习算法对CWD碳储量进行估算的研究尚不多见。此外,相对国外研究而言,国内研究主要局限于小尺度范围。文章据此提出未来CWD碳储量研究的发展方向:(1)拓展研究尺度,建立CWD碳储量长期观测体系;(2)深入开展不同森林生态系统CWD碳储量对气候变化的响应机制研究;(3)探索更加多元化的CWD碳储量计量方法;(4)深入探讨CWD碳库对土壤碳库与植被碳...     

滨海蓝碳湿地碳汇速率测定方法及中国的研究现状和挑战

滨海盐沼、红树林和海草床蓝碳湿地生态系统具有高效的固碳-储碳能力,准确测定滨海蓝碳湿地生态系统碳汇速率,对于评估滨海湿地碳中和能力、生态恢复新增碳汇规模及碳贸易至关重要。深入思考滨海蓝碳湿地生态系统碳汇定义的内涵,提出狭义碳汇和广义碳汇的概念,介绍沉积物碳累积+植被净初级生产力法以及生态系统碳通量收支法2个目前国际上应用最多的滨海蓝碳湿地碳汇速率测定方法,特别是深入分析作为开放系统的滨海盐沼生态系统和海草床生态系统碳汇速率测定面临的诸多问题与挑战,梳理中国红树林、滨海盐沼和海草床生态系统碳汇速率的测定结果及国家尺度滨海蓝碳湿地生态系统碳汇规模,最后提出中国在滨海蓝碳湿地碳汇速率测定实践中急需加强的基础研究领域,以期为科学地计量中国滨海蓝碳湿地生态系统碳汇速率与碳汇规模提供方法参考和技术支撑。     

土壤碳库构成研究进展

土壤碳库是陆地生态系统中最大的碳库。土壤碳库的构成影响其累积和分解,并直接影响全球陆地生态系统碳平衡,同时也影响土壤质量变化。弄清土壤碳库的组分及构成,是进一步研究土壤碳库变化机制的关键。综述了土壤碳库的组分和构成,对有机碳库进行不稳定性有机碳库和稳定有机碳库归类,描述各类碳库的性质,并对各类碳库的分析测定方法进行了评述。提出在土壤碳构成中增加黑碳和煤炭(碳)以完善土壤有机碳构成框架。在未来研究中,应加强土壤无机碳及湿地土壤和新开发新复垦的重构土壤碳库构成及变化,各类碳库化学构成,交叉重叠的定量关系,碳库之间的转化及在土壤中的迁移,黑碳对土壤碳库稳定性及土壤质量的影响,煤开采扰动区煤炭(碳)对土壤质量的影响及环境效应等科学问题的研究。     

Spatial patterns of China's carbon sinks estimated from the fusion of remote sensing and field-observed net primary productivity and heterotrophic respiration

Accurately assessing the carbon sink and spatial distribution pattern of China's terrestrial ecosystems is of great significance to the implementation of climate change and carbon neutrality strategy. However, the views of various studies are still very controversial due to the differences in carbon sink estimation methods and data sources. In this study, vegetation net primary productivity (NPP) and ecosystem heterotrophic respiration (Rh) estimation models were constructed based on machine learning methods by fusing multisource data, such as remote sensing and ground observation data. The magnitude and spatial pattern of carbon sink in China from 2000 to 2018 were then revealed, and the carbon sink capacity of various ecosystems was quantitatively assessed. The main conclusions include the following: (1) The use of scale-matched carbon input and output data can help reduce the system error in carbon sink estimation. (2) China's terrestrial ecosystem carbon sink since the twenty-first century is approximately 0.458 Pg C/yr, which is equivalent to 22.72% of China's anthropogenic carbon emissions. (3) Deciduous forest has a higher carbon sink capacity than evergreen forest, while coniferous forest has a more stable carbon sink capacity than broad-leaved forest. The magnitude and spatial distribution of carbon sink in China reported in this study provides a scientific reference for achieving carbon neutrality and sustainable development.     

基于自然的碳达峰、碳中和解决方案：关键议题

实现碳达峰、碳中和是我国生态文明建设的重点战略方向。按照“目标设计-要素布局-方案实施”的基本逻辑，可以对碳达峰、碳中和的工作要点进行系统梳理。基于自然的解决方案(Nature-based Solutions, NbS)是国际社会普遍认可的生态恢复前沿理念，具备可持续性、系统性、尺度性、适应性四方面核心特质，能够有效回应“双碳”目标的工作要求。碳达峰、碳中和与NbS在目标导向和实践思路上高度契合，二者均以可持续发展为主要目标，NbS八项实施准则亦能够为“双碳”工作的积极推进提供全面系统的行动框架。结合NbS实施准则，具体提出基于自然的碳达峰、碳中和八大关键议题：(1)统筹减污降碳协同增效的政策体系；(2)强化尺度级联的传导机制；(3)构建基于自然的固碳途径；(4)完善多元化的碳汇交易；(5)兼顾社会公平的参与机制；(6)促进基于权衡的路径选择；(7)创新动态连续的监测手段；(8)推动NbS在“双碳”领域主流化，以期支撑国家碳达峰、碳中和可持续解决方案的落实。     

Sources of carbon productivity change: A decomposition and disaggregation analysis based on global Luenberger productivity indicator and endogenous directional distance function

The measurement of carbon productivity makes the effort of global climate change mitigation accountable and helps to formulate policies and prioritize actions for economic growth, energy conservation, and carbon emissions control. Previous studies arbitrarily predetermined the directions of directional distance function in calculating the carbon productivity indicator, and the traditional carbon productivity indicator itself is not capable of identifying the contribution of different energy driven carbon emissions in carbon productivity change. Through utilizing an endogenous directional distance function selecting approach and a global productivity index, this paper proposes a global Luenberger carbon productivity indicator for computing carbon productivity change. This carbon productivity indicator can be further decomposed into three components that respectively identify the best practice gap change, pure efficiency change, and scale efficiency change. Moreover, the carbon productivity indicator is shown as a combination of individual carbon emissions productivity indicators that account for the contribution of different fossil fuel driven carbon emissions (i.e. coal driven CO₂, oil driven CO₂, and natural gas driven CO₂) toward the carbon productivity change. Our carbon productivity indicator is employed to measure and decompose the carbon productivity changes of 37 major carbon emitting countries and regions over 1995–2009. The main findings include: (i) endogenous directions identifying the largest improvement potentials are noticeably different from exogenous directions in estimating the inefficiencies of undesirable outputs. (ii) Carbon productivity indicator calculated with the consideration of emission structure provides a more significant estimation on productivity change. (iii) The aggregated carbon productivity and the specific energy driven carbon productivities significantly improve over our study period which are primarily attributed to technical progress. (iv) Empirical results imply that policies focused on researching and developing energy utilization and carbon control technologies might not be enough; it is also essential to encourage technical efficiency catching-up and economic scale management.     

“双碳”目标下闽三角碳排放脱钩状态及驱动机制分析

快速城市化背景下,建设低碳城市群是实现"双碳"目标的最佳方式。在碳排放核算的基础上,使用Tapio脱钩模型和LMDI方法对闽三角以及厦门、漳州和泉州的脱钩状态和碳排放的驱动机制进行了研究。主要结论如下：（1）2005-2017年闽三角碳排放和人均碳排放均持续增加,二者有相同的变化趋势。闽三角的工业中心泉州有最高的碳排放和人均碳排放。发展型城市漳州碳排放最低,但碳排放和人均碳排放增长率均最高。服务型城市厦门碳排放增长率最低。（2）闽三角的脱钩状态逐渐改善,平均脱钩系数为1.03,脱钩状态为扩张性连接。厦门、漳州和泉州的平均脱钩系数分别为0.45、2.70和1.10,3个城市分别以弱脱钩、扩张负脱钩和扩张性连接状态为主。（3）人均GDP和人口规模是闽三角碳排放的正向因素,能源结构和能源强度是负向因素。正向因素的贡献在下降,负向因素的贡献在升高。人均GDP和能源结构分别对漳州和厦门碳排放有最强的促进和抑制效应。能源强度对3个城市碳排放变化的效应不同。（4）人口扩张促进碳排放增加,使碳排放与经济发展无法脱钩。人口规模对闽三角碳减排无脱钩努力。能源结构优化和能源强度下降有助于碳排放与经济发展脱钩,是闽三角碳减排的强脱钩努力和弱脱钩努力。能源强度对泉州碳减排无脱钩努力。优化能源结构是闽三角实现碳减排和"双碳"目标的关键。已经脱钩的厦门宜尽早制定碳达峰行动计划,引领闽三角的碳达峰行动。漳州可通过升级产业结构实现减排。泉州必须提升能源效率才能降低碳排放。     

闽三角城市群碳达峰的多情景模拟分析

碳达峰、碳中和是应对气候变化的关键手段。在闽三角碳排放核算的基础上,运用STIRPAT模型建立了碳排放与人口规模、城镇化率、人均GDP、能源强度和产业结构间的函数关系。结合情景分析法,模拟上述因素在不同变化速率下的目标值,对2021-2050年的碳排放及碳排放强度进行了预测,为闽三角碳达峰提供时间和技术路径参考。此外,还引入人均GDP二次方指标,验证EKC假说的存在性。结论如下：（1）能源强度是闽三角碳排放的负向因素,其他因素均为正向因素。产业结构和人均GDP分别对闽三角碳排放有最大和最小的影响。（2）人均GDP的二次方与碳排放间的系数为正,表明碳排放和人均GDP间不存在倒"U"型曲线关系。闽三角碳排放和人均GDP间的关系不符合EKC假说的描述。（3）基准情景下,闽三角碳排放和碳排放强度持续增加,碳排放不能达峰。厦门的碳排放强度将持续下降。低碳情景下,厦门最可能在2020年实现达峰目标。低发展、中减排情景下,闽三角在2030年实现碳达峰,碳排放最大值为0.57亿t。（4）所有情景下,闽三角都未实现2030年碳排放强度比2005年下降60%-65%的目标。基于上述结论,为闽三角碳达峰提供如下意见：（1）优化产业结构。漳州和泉州既需要升级生产技术又需要淘汰高能耗高排放产业,发展高端制造和智能制造等;（2）优化能源消费结构。"十四五"期间重点建设漳州核电、厦门水电、泉州热能等可再生能源工程。加快特高压电网的建设,减少化石能源的消耗;（3）尽快制定厦门的碳达峰计划,引领闽三角碳达峰行动。     

基于小尺度的高寒牧区碳排放估算——以甘南州合作市为例

碳排放是目前国内外研究的热点问题。纵观碳排放计算,关键涉及到两个环节:一是研究尺度的选择,二是评估参数(即碳排放/吸收系数)的确定。高寒牧区还必须充分考虑牲畜碳排放。以甘南州合作市为例,将研究尺度缩小到41个行政村,并采用最新的土地二调数据,对土地利用碳排放和碳汇、生活和牲畜碳排放进行了系统地测算。结果表明:(1)从土地利用的角度考察,合作市总碳排放表征为"碳亏"态势。总碳排放量为24374.82 t/a,其中土地利用碳排放量为4908.21 t/a,牲畜代谢碳排放量为3703.94 t/a,城乡居民生活碳排放量为15762.67 t/a。而碳汇量仅为1949.74 t/a,"碳亏"量为22425.08 t/a。(2)牲畜是高寒牧区呼吸碳排放的主体,其碳排量为3703.94t/a,其中牛是碳排放的主体,其碳排量占90%以上。(3)城乡居民生活碳排量为15762.67t/a,城镇明显高于农村,生存型碳排放强度高于发展型碳排放强度。(4)碳排放局分布势面与碳汇分布局势面基本呈反向分布态势,但总的碳排放格局取决于碳排放而非碳汇,空间分布表现为从城区—半农半牧区—纯牧区逐级递减的趋势。     

西南岩溶区植被碳循环研究进展

由于岩溶关键带是地球关键带系统中重要的部分,岩溶区的植被是陆地生态系统重要的碳汇项,岩溶区植被的地上部分通过植物生长固碳的同时其地下部分的碳储量也非常可观,地下生物量生长和凋落物分解也会提高土壤有机碳和无机碳的含量,因此岩溶区植被碳循环已成为当前岩溶碳汇研究的热点之一。该文梳理了近四十年来岩溶植被固碳过程的研究文献,阐述了西南岩溶区植被特有的生理学特征,重点论述了以下4个方面的内容:(1)西南岩溶区植被生物量、生产力、碳储量评估;(2)西南岩溶区植被时空变化格局与碳源汇效应;(3)岩溶区植被碳利用特殊机制;(4)岩溶区植被碳循环模型预测与碳汇潜力。同时,提出了目前研究中存在的问题,并对今后的研究方向进行了展望,认为今后应在岩溶区植被碳循环的相关参数系统测定和机理过程研究,精细识别西南岩溶地区植被景观类型、量化固碳过程,以及对岩溶植被碳循环模型进行校正和修改等方面开展研究。该文可为深入理解岩溶区碳的时空演化规律、探索区域碳循环机理提供参考。     

The synthesis of amino acids by Methanobacterium omelianskii

1. Methanobacterium omelianskii was grown on (14)CO(2) and unlabelled ethanol, or on [1-(14)C]- or [2-(14)C]-ethanol and unlabelled carbon dioxide. The cell protein was hydrolysed and certain of the amino acids were isolated and degraded. 2. Carbon from both carbon dioxide and ethanol is used for biosynthesis of amino acids, and in most cases ethanol is incorporated as a C(2) unit. Ethanol carbon atoms and carbon dioxide carbon atoms apparently enter the same range of compounds. Ethanol and carbon dioxide are equally important as sources of cell carbon. 3. The origins of carbon atoms of aspartate, alanine, glycine, serine and threonine are consistent with the synthesis of these amino acids, by pathways known to exist in aerobic organisms, from pyruvate arising by a C(2)+C(1) condensation. The proportion of total radioactivity found in C-1 of lysine, proline, methionine and valine is consistent with synthesis of these amino acids by pathways similar to those found in Escherichia coli. Isoleucine is probably formed by carboxylation of a C(5) precursor formed entirely from ethanol. Glutamate is formed by an unknown pathway.     

潮汐作用和干湿交替对盐沼湿地碳交换的影响机制研究进展

潮汐盐沼湿地具有高的碳积累速率和低的CH_4排放量,是地球上最密集的碳汇之一。同时,气候变暖和海平面上升可能使得盐沼湿地更迅速的捕获和埋藏大气中的CO_2,因此盐沼湿地的"蓝碳"在减缓气候变化方面扮演着重要角色。潮汐盐沼湿地与其他湿地类型最大的区别和最显著的特征是在周期性潮汐作用下出现淹没和暴露,同时伴随盐分表聚与淋洗的干湿交替,可能是控制盐沼湿地碳交换过程和碳收支平衡的关键因素。但是,当前潮汐水动力过程及其周期性干湿交替对盐沼湿地碳交换关键过程和碳汇形成机制的影响尚不十分清楚。另外,以往相关研究通常孤立地考虑垂直方向上CO_2或CH_4交换或横向方向上的可溶性有机碳(DOC)、可溶性无机碳(DIC)、颗粒有机碳(POC)交换通量对盐沼湿地碳平衡进行评估,显然不够准确。因此,为了精确评估和预测盐沼湿地蓝碳的吸存能力,必须系统研究潮汐不同阶段对盐沼湿地碳交换过程的影响;深入分析潮汐作用下盐沼湿地碳交换的微生物机制;关注潮汐水动力作用对盐沼湿地DOC、DIC和POC产生、释放以及向邻近水体输出的影响;阐明潮汐作用对盐沼湿地碳汇形成机制的影响;纳入潮汐水动力过程作为变量,建立盐沼湿地碳循环模型。     

The carbon cycle on early Earth--and on Mars?

One of the goals of the present Martian exploration is to search for evidence of extinct (or even extant) life. This could be redefined as a search for carbon. The carbon cycle (or, more properly, cycles) on Earth is a complex interaction among three reservoirs: the atmosphere; the hydrosphere; and the lithosphere. Superimposed on this is the biosphere, and its presence influences the fixing and release of carbon in these reservoirs over different time-scales. The overall carbon balance is kept at equilibrium on the surface by a combination of tectonic processes (which bury carbon), volcanism (which releases it) and biology (which mediates it). In contrast to Earth, Mars presently has no active tectonic system; neither does it possess a significant biosphere. However, these observations might not necessarily have held in the past. By looking at how Earth's carbon cycles have changed with time, as both the Earth's tectonic structure and a more sophisticated biology have evolved, and also by constructing a carbon cycle for Mars based on the carbon chemistry of Martian meteorites, we investigate whether or not there is evidence for a Martian biosphere.     

Biofixation of carbon dioxide by Spirulina sp. and Scenedesmus obliquus cultivated in a three-stage serial tubular photobioreactor

The increase in the concentration of atmospheric carbon dioxide is considered to be one of the main causes of global warming. As estimated by the Intergovernmental Panel on Climate Change (IPCC) criteria, about 10-15% of the gases emitted from the combustion coal being in the form of carbon dioxide. Microalgae and cyanobacteria can contribute to the reduction of atmospheric carbon dioxide by using this gas as carbon source. We cultivated the Scenedesmus obliquus and Spirulina sp. at 30 degrees C in a temperature-controlled three-stage serial tubular photobioreactor and determined the resistance of these organisms to limitation and excess of carbon dioxide and the capacity of the system to fix this greenhouse gas. After 5 days of cultivation under conditions of carbon limitation both organisms showed cell death. Spirulina sp. presenting better results for all parameters than S. obliquus. For Spirulina sp. the maximum specific growth rate and maximum productivity was 0.44 d(-1), 0.22 g L(-1)d(-1), both with 6% (v/v) carbon dioxide and maximum cellular concentration was 3.50 g L(-1) with 12% (v/v) carbon dioxide. Maximum daily carbon dioxide biofixation was 53.29% for 6% (v/v) carbon dioxide and 45.61% for 12% carbon dioxide to Spirulina sp. corresponding values for S. obliquus being 28.08% for 6% (v/v) carbon dioxide and 13.56% for 12% (v/v) carbon dioxide. The highest mean carbon dioxide fixation rates value was 37.9% to Spirulina sp. in the 6% carbon dioxide runs.     

Global and regional importance of the tropical peatland carbon pool

Accurate inventory of tropical peatland is important in order to (a) determine the magnitude of the carbon pool; (b) estimate the scale of transfers of peat‐derived greenhouse gases to the atmosphere resulting from land use change; and (c) support carbon emissions reduction policies. We review available information on tropical peatland area and thickness and calculate peat volume and carbon content in order to determine their best estimates and ranges of variation. Our best estimate of tropical peatland area is 441 025 km² (～11% of global peatland area) of which 247 778 km² (56%) is in Southeast Asia. We estimate the volume of tropical peat to be 1758 Gm³ (～18–25% of global peat volume) with 1359 Gm³ in Southeast Asia (77% of all tropical peat). This new assessment reveals a larger tropical peatland carbon pool than previous estimates, with a best estimate of 88.6 Gt (range 81.7–91.9 Gt) equal to 15–19% of the global peat carbon pool. Of this, 68.5 Gt (77%) is in Southeast Asia, equal to 11–14% of global peat carbon. A single country, Indonesia, has the largest share of tropical peat carbon (57.4 Gt, 65%), followed by Malaysia (9.1 Gt, 10%). These data are used to provide revised estimates for Indonesian and Malaysian forest soil carbon pools of 77 and 15 Gt, respectively, and total forest carbon pools (biomass plus soil) of 97 and 19 Gt. Peat carbon contributes 60% to the total forest soil carbon pool in Malaysia and 74% in Indonesia. These results emphasize the prominent global and regional roles played by the tropical peat carbon pool and the importance of including this pool in national and regional assessments of terrestrial carbon stocks and the prediction of peat‐derived greenhouse gas emissions.     

京津冀地区碳排放时空格局变化及其驱动因子

人类对陆地生态系统的改变是碳排放增加的主要原因。在“双碳”目标背景下探索土地利用变化与碳排放的动态关系,有助于区域土地低碳可持续利用。研究基于土地利用转移视角,采用重心-标准差椭圆方法揭示了京津冀地区土地利用碳排放时空格局演化特征,评估了碳排放与生态环境、社会经济发展的协调程度,并借助改进的Kaya模型和LMDI分解模型定量分析了土地利用变化对碳排放的影响程度。结果表明：(1)建设用地的转入是土地利用碳排放增加的主要来源,引起碳排放量增加15844.36万t;耕地、草地向林地、水域的转变促进了地区固碳能力的提升。(2)土地利用碳排放空间分布格局呈现出东北-西南方向向中心进一步聚集的趋势,并且东-西向聚集趋势大于南-北向。(3)京津冀地区整体碳排放与生态环境的协调性呈向好趋势发展,但大部分地区碳排放与社会经济发展出现失衡现象,地区间碳生产力差异逐渐增大。(4)经济水平是促进碳排放增加的最显著因素,单位GDP用地强度是抑制碳排放增加的最主要因素。分析结果表明,严格控制建设用地的无序扩张是促进低碳土地利用的基础,低碳经济发展是促进地区减碳的重要途径。     

大兴安岭地区天然落叶松林乔木碳增量的研究

基于1990~2010年黑龙江省大兴安岭地区4期森林资源连续清查的602块固定样地数据,分析了大兴安岭地区天然落叶松林年均枯损木碳释放量、进界木碳储量、碳净增量的动态变化以及随立地质量、林分密度的变化规律。结果表明：该地区各龄组碳释放量在0.133 7~0.484 1 t·hm^-2·a,碳释放量随着龄组的增大而增大;进界木碳储量在幼龄林时较大,为0.128 2 t·hm^-2·a,近熟林最小,为0.040 0 t·hm^-2·a,其他龄组差异不大;碳净增量随着龄组的增大而减小,幼龄林、中龄林、近、成、过熟林分别为1.374 9、0.982 1、0.649 9、0.538 1、0.240 7 t·hm^-2·a;相同立地质量条件下,各龄组碳释放量与林分密度成正比。幼龄林、中龄林、成熟林随林分密度的增大进界木碳储量减小,近熟林和过熟林规律不明显。除幼龄林之外,各龄组在林分密度为中时,林分碳净增量最大;相同林分密度条件下,各龄组（近熟林、成熟林无明显规律）碳释放量与立地质量成负相关关系。各龄组（过熟林除外）立地质量越好,进界木碳储量越小;相同林分密度条件下,立地质量越好,碳净增量越大。     

喀斯特山地不同微地貌下土壤碳氮磷空间异质性及生态化学计量特征

喀斯特地区特殊地质背景造就复杂破碎的地形发育出多样的微地貌,这使得清晰地认识土壤碳氮磷的空间异质性及生态化学计量特征存在困难。基于实地调查、土壤采样、实验测试的结果数据,引入混合效应模型评估方法结合变异系数,分别从全量(土壤有机碳、全氮、全磷)及有效态(活性有机碳、碱解氮及速效磷)两方面,揭示不同微地貌类型下土壤碳氮磷空间异质性及其生态化学计量特征。结果显示：(1)不同微地貌类型下土壤有机碳、全氮、全磷对碳氮磷比值的耦合解释度为：土面(91.09%)>石沟(91.02%)>石坑(84.63%)>石洞(80.17%)>石缝(73.20%),土面的空间异质性最低而石缝最高。(2)有效态方面,活性有机碳、碱解氮和速效磷对碳氮磷比值的耦合解释度特征为：石缝(84%)>石洞(58.15%)>土面(47.80%)>石坑(44.06%)>石沟(32.18%),说明石缝微地貌的土壤活性有机碳、碱解氮及速效磷空间异质性最低。(3)不同微地貌类型下土壤全量碳氮磷生态化学计量的变异系数差异均在50%以上(C/N 80%、C/P 53.57%、N/P 69.33...     

低碳导向下土地覆被演变模拟——以深圳市为例

全球碳排放水平的不断增加引起的全球变暖越发严重,导致了严重的自然灾害和经济损失,这种失衡发展的态势促使着各个国家开始探索低碳环保的发展模式。为了探究何种土地利用组成可以更好的为低碳城市服务,以深圳市为研究区,结合2020年土地利用现状结构和2020年土地利用规划结构分别估算出碳汇最大化情景和碳排放量最小化情景下2020年各土地利用类型的数量结构,并运用FLUS模型模拟出深圳市土地利用类型在这两种情景下的空间分布特征。最后,从碳密度和碳排放视角对比这两种情景的低碳效益。研究结果如下：①碳汇最大化和碳排放最小化情景下土地利用总碳盈余均比2020年少,且碳汇最大化情景下土地利用总碳盈余最小。碳汇最大化情景下耕地、园地和林地面积增加而水域和建设用地减少,碳排放最小化情景下园地和林地面积增加来源于草地、水域和建设用地的减少,这两种低碳情景的碳汇能力增强而碳排放量减少;②碳汇最大化和碳排放最小化情景下林地明显增加故而土地利用总碳盈余均比实际情景小,而园地和草地的缩减和扩张是引起两种低碳情景碳密度和碳排放量有差异的主要原因。碳汇最大化和碳排放最小化情景下,西部和东南部主要是碳密度增加和碳排放减少的区域,而中部是碳密度减少和碳排放增加的区域。因此对中部区域进行重点调控,有利于深圳市碳中和和碳达峰的实现。研究可以为深圳的低碳发展提供规划建议,同时给其他区域的低碳规划提供参考意见。     

不同退耕年限对菜子湖湿地表土有机碳组分与质量的影响

退耕还湿后土壤有机碳不同组分变化和有机碳质量的评价是退耕湿地生态恢复研究的重要内容。对安徽菜子湖湿地不同退耕年限(2、5、8、10和20a)的湿地土壤总有机碳(TOC)、颗粒态有机碳(POC)和矿物结合态有机碳(MOC)的含量与有机碳质量进行了研究。结果表明,随着退耕年限增加,土壤TOC、POC、MOC含量均有显著增加,且退耕后土壤有机碳增加过程中,以POC为代表的活性有机碳优先恢复,而以MOC为代表的稳定有机碳恢复相对滞后。随着退耕年限增加,POC/MOC、TOC和POC的层化比(SR)增加,反映有机碳的活性明显提高。退耕期间所增加的有机碳在组成上以易降解的POC为主,在分布上以易降解的表层有机碳居多,因此有机碳库的稳定性并未明显提高。通过计算碳库管理指数(CPMI),发现土壤质量随着退耕年数增加而提高,根据CPMI变化趋势线,土壤质量大约需要13a才能恢复到对照水平;退耕湿地生态恢复过程中,有机碳数量(碳库指数CPI)恢复较快,而有机碳质量(碳库活度指数AI)恢复需要较长的时间,二者分别需7.6和22.7a恢复到对照水平。