Effects of urbanization and forest type on species composition and diversity,forest characteristics,biomass carbon sink,and their associations in Changchun,Northeast China:implications for urban carbon stock improvement

Differences in forest attributes and carbon sequestration of each organ and layer between broadleaved and conifer forests of central and outer urban areas are not well-defined,hindering the precise management of urban forests and improvement of function.To clarify the effect of two forest types with different urbanization intensities,we determined differences in vegetation composition and diversity,structural traits,and carbon stocks of 152 plots(20 m×20 m)in urban park forests in Changchun,which had the largest green quantity and carbon density effectiveness.We found that 1.1-fold thicker and healthier trees,and 1.6-to 2.0-fold higher,healthier,denser,and more various shrubs but with sparser trees and herbs occurred in the central urban forests(p<0.05)than in the outer forests.The conifer forests exhibited 30–70%obviously higher tree aboveground carbon sequestration(including stem and leaf)and 20%bigger trees,especially in the outer forests(p<0.05).In contrast,1.1-to 1.5-fold higher branch stocks,healthier and more diverse trees were found in broadleaved forests of both the inner and outer forests(p<0.05).Plant size and dominant species had similarly important roles in carbon stock improvement,especially big-sized woody plants and Pinus tabuliformis.In addition,a higher number of deciduous or needle species positively affected the broadleaved forest of the central urban area and conifer forest of the outer urban area,respectively.These findings can be used to guide precise management and accelerate the improvement of urban carbon function in Northeast China in the future.

Discussion on the Ecological Effects of Carbon Source/Sink Conversion in Wetlands

This study explored the ecological effects of the transformation of carbon source and carbon sink in wetlands, that were discussed from four aspects: atmosphere, ocean, plants and soil. The results showed that the wetland changed from carbon sink to carbon source, which led to the increase of CO_2 emissions in the atmosphere and the intensification of greenhouse effect, which made the earth face the threat of global warming. At the same time, the content of CO_2 in seawater is increased; the pH value of seawater decreases; the balance of seawater acid-base is destroyed; and the ocean acidification is caused.

Influence of the biological carbon pump effect on the sources and deposition of organic matter in Fuxian Lake, a deep oligotrophic lake in southwest China

Biological carbon pumping(BCP)is a key process in which dissolved inorganic carbon in terrestrial aquatic ecosystems is utilized by aquatic autotrophs for photosynthesis and transformed into autochthonous organic matter(AOC).However,the mechanisms underlying BCP and the amount of generated AOC deposited effectively,are still poorly understood.Therefore,we conducted a systematic study combining modern hydrochemical monitoring and a sediment trap experiment in Fuxian Lake(Yunnan,SW China),the second-deepest plateau,oligotrophic freshwater lake in China.Temperature,pH,EC(electrical conductivity),DO(dissolved O2),[HCO3^-],[Ca^2+],SIc,partial CO2(pCO2)pressure,and carbon isotopic compositions of HCO3^-(δ^13CDIc)in water from Fuxian Lake all displayed distinct seasonal and vertical variations.This was especially apparent in an inverse correlation between pCO2 and DO,indicating that variations of hydrochemistry in the lake water were mainly controlled by the metabolism of the aquatic phototrophs.Furthermore,the lowest C/N ratios and highestδ^13Corg were recorded in the trap sediments.Analyses of the C/N ratio demonstrated that the proportions of AOC ranged from 30%to 100%of all OC,indicating that AOC was an important contributor to sedimentary organic matter(OC).It was calculated that the AOC flux in Fuxian Lake was 20.43 t C km^-2 in 2017.Therefore,AOC produced by carbonate weathering and aquatic photosynthesis could potentially be a significant carbon sink and may have an important contribution to solving the lack of carbon sinks in the global carbon cycle.

Distribution, burial fluxes and carbon sink effect of sedimentary organic carbon in the eastern China seas

The ocean is the largest active carbon reservoir on Earth. Organic carbon(OC), as the primary species of carbon sequestration in the ocean, plays an important role in the global carbon cycle through its deposition and burial. In this study,sedimentary OC data from 5796 stations, together with relevant geochemical and sedimentological parameters in the Bohai Sea,Yellow Sea, and East China Sea(BYES) were used to summarize and elucidate the distribution and burial patterns of sedimentary OC, and assess carbon sink effect of sedimentary OC burial. The results show that the OC content in the sediments of the BYES ranges from 0.00% to 2.12%, with an average content of 0.47%±0.26%. OC content is significantly correlated with finegrained sediments, with an average OC content in mud areas being 39% higher than that in non-mud areas. Modern OC buried in the BYES are mainly deposited in 7 major mud areas, with a total sedimentary OC burial flux of approximately 8.20 Mt C yr^(–1).Among them, the burial flux of biospheric OC is 6.92 Mt C yr^(–1), equivalent to the OC consumption amount of silicate weathering of the 9 major river basins in the eastern China. In its natural state, the annually sequestered OC in the sediments of the eastern China seas is equivalent to 25.37 Mt of atmospheric CO_(2), indicating a significant carbon sink effect. The distribution and burial of terrigenous OC in the BYES are mainly influenced by the large river inputs and complex marine hydrodynamic environment,while human activities such as dam construction have significantly altered the OC burial in these coastal mud areas.

Global significance of the carbon cycle in the karst dynamic system:evidence from geological and ecological processes

On the basis of proposing the existence of a karst carbon cycle and carbon sink at a watershed scale,this paper provides four pieces of evidence for;the integration of geology and ecology during the carbon cycle processes m the karst dynamic system,and estxmated the karst carbon sink effect using the methods of comparative monitoring of paired watersheds and the carbon stable isotope tracer technique.The results of the soil carbon cycle in Maocun,Guilin,showed that the soil carbon cycle in the karst area,the weathering and dissolution of carbonate rocks under the soil,resulted in a lower soil respiration of 25% in the karstoarea than in a non-karst area (sandstone and shale),and the carbon isotope results indicated that 13.46% of the heavy carbon of the hmestone is involved in the soil carbon cycle.The comparative monitoring results m paxred watersheds,suggesting that the HCO3 concentration m a karst spring is 10 times that of a rivulet in a non-karst area,while the concentration of inorganic carbon flux is 23.8 times.With both chemical stoichiometry and carbon stable isotopes,the proportion of carbon in karst springs derived from carbonate rocks was found to be 58.52% and 37.65% respectively.The comparison on carbon exchange and isotopes at the water-gas interface between the granite and carbonate rock basins in the Li River showed that the CO2 emission of the karst water is 10.92 times that of the allogenic water from the non-karst area,while the carbon isotope of HCO3^- in karst water is lighter by 8.62%.However,this does not mean that the karst water body has a larger carbon source effect.On the contrary,it means the karst water body has a greater karst carbon sink effect.When the karst subterranean stream in Zhaidi,Guilin,is exposed at the surface,carbon-rich karst water stimulated the growth of aquatic plants.The values of carbon stable isotopes in the same species of submerged plants gradually becomes heavier and heavier,and the 512 m flow process has a maximum range of 15.46%.The calculation results showed that 12.52% of inorganic carbon is converted into organic carbon.According to the data that has been published,the global karst carbon sink flux was estimated to be 0.53-0.58 PgC/a,equivalent to 31.18%-34.41% of the global forest carbon sink flux.In the meanwhile,the karst carbon sink flux in China was calculated to be 0.051 PgC/a,accounting for 68% of its forest carbon sink flux.

Seasonal compensation implied no weakening of the land carbon sink in the Northern Hemisphere under the 2015/2016 El Niño

The recurrent extreme El Niño events are commonly linked to reduced vegetation growth and the land carbon sink over many but discrete regions of the Northern Hemisphere(NH).However,we reported here a pervasive and continuous vegetation greening and no weakened land carbon sink in the maturation phase of the 2015/2016 El Niño event over the NH(mainly in the extra-tropics),based on multiple evidences from remote sensing observations,global ecosystem model simulations and atmospheric CO_(2)inversions.We discovered a significant compensation effect of the enhanced vegetation growth in spring on subsequent summer/autumn vegetation growth that sustained vegetation greening and led to a slight increase in the land carbon sink over the spring and summer of 2015(average increases of 23.34%and 0.63%in net ecosystem exchange from two independent datasets relative to a 5-years average before the El Niño event,respectively)and spring of 2016(6.82%),especially in the extra-tropics of the NH,where the water supply during the pre-growing-season(November of the previous year to March of the current year)had a positive anomaly.This seasonal compensation effect was much stronger than that in 1997 and 1998 and significantly alleviated the adverse impacts of the 2015/2016 El Niño event on vegetation growth during its maturation phase.The legacy effect of water supply during the pre-growing-season on subsequent vegetation growth lasted up to approximately six months.Our findings highlight the role of seasonal compensation effects on mediating the land carbon sink in response to episodic extreme El Niño events.

Carbon Capture Storage and Utilization of Pinctada margaritifera Black Lip Pearl Oyster in French Polynesia

Trees,generally,are used to remove carbon dioxide from the atmosphere.Other methods need to be considered.NASA(National Aeronautics and Space Administration)uses iron lime to increase the plankton uptake from the ocean bed.We can remove the carbon through the practice of shellfish farming.In French Polynesia,oysters mean pearl oyster farming.An independent assessment of the shellfish industry would be required to determine the carbon sequestration and generate carbon offsets through this method.CO2 sink in pearl oysters shell,called MOP(Mother Of Pearl)can be allocated into precious button and objects or powder in poultry farming.

基于内容分析法的城镇雨水系统碳排放核算研究进展

采用内容分析法,从核算对象、核算范围、核算方法及排放因子等方面,对现有城镇雨水系统碳排放核算研究情况进行了系统回顾。结果表明:现有研究基本明确了雨水系统碳排放核算公式,为开展多尺度雨水系统碳排放核算奠定了方法基础;现有研究核算了部分雨水设施部分阶段的碳排放因子,但存在核算范围不一致、方法不统一、排放因子不透明等问题,不同研究结果之间可比性较差,核算结果具有很大不确定性;雨水设施碳排放因子完整性较差,与形成统一规范的雨水系统碳排放核算体系存在一定的差距。为规范雨水系统碳排放核算体系,未来研究应重点关注截留式排水体制下雨水系统核算边界划分、直接碳排放精准测度和水能利用的碳抵消效应,逐步构建适用于雨水系统碳排放核算的综合因子数据库。

基于碳汇作用的西安市城市道路植物配置优化策略研究

为使城市道路植物配置最大限度地发挥绿色植物的生态功能,进一步推动我国“双碳”政策的实施,选取西安市长安区西部大道东段道路作为研究范围,通过对实测场地内的植物群落调研,讨论配置现状与CO_(2)浓度间的关系;利用ENVI-met在实测分析的基础上,定量地从郁闭度、树龄和群落类型3个方面,给出针对西安市城市道路碳收支平衡下的植物配置具体优化策略。结果表明,道路绿带能对CO_(2)发挥一定的削减和封存作用;同等配置条件下的道路绿带中,绿带宽度越大、绿量越高的绿色空间的固碳作用也越高;通过线性拟合得出郁闭度、树龄和群落类型中,群落类型对CO_(2)浓度的影响程度最大。

尕海湿地固碳功能及其抵消能源碳排放评估

甘肃省作为中国重要的生态屏障,省内尕海湿地是国际重要湿地之一,研究尕海湿地能源抵消效应对甘肃省更好地实现“双碳”目标和维护生态安全具有重要意义。根据尕海不同类型湿地的占地面积、土壤的有机碳密度计算出尕海湿地的碳储存总量,以及通过部门法计算出甘肃省2021年不同行业能源消耗的碳排放总量。结果表明,尕海湿地能源抵消效率呈现出明显的类型差异,草本泥炭地和高山湿地的抵消效率相近,永久性沼泽湿地的能源抵消能力最低。因此,针对提升尕海湿地能源抵消率提出以下建议:改良湿地相关的计算方法、完善湿地保护政策、拓宽融资渠道、保护湿地资源,提升抵消能力和提升专业水平,增强环保意识。

保护性耕作机械能否带动保护性耕作净碳汇的空间外溢?——基于农机跨区服务视角

农机跨区服务推动了以农业机械为载体的保护性耕作技术及其净碳汇的空间外溢。本文以2000—2020年中国30个省份(不含港澳台及西藏)为研究样本,运用探索性空间数据分析法揭示保护性耕作机械及其净碳汇在空间上的集聚特征,并通过空间杜宾模型定量分析保护性耕作机械对其净碳汇的空间溢出效应。研究发现:1)保护性耕作机械动力及其净碳汇在2000—2020年期间均呈增长态势,年均增长率分别为12.52%和7.42%,两者在空间上主要表现为“高-高集聚”和“低-低集聚”的区域集聚特征。2)保护性耕作机械动力通过跨区服务能够显著带动保护性耕作净碳汇实现空间外溢。具体表现为保护性耕作机械动力对周边省份保护性耕作净碳汇会产生正向空间溢出效应,且主要归因于秸秆还田机械的跨区作业。3)保护性耕作机械动力对其净碳汇的空间溢出效应因时间、地形、粮食作物主产区而异。具体来说,其空间溢出效应在2004—2009年间和2010—2013年间显著为正,并呈增加趋势;在平原地区,其空间溢出效应为正,在丘陵山区则为负;保护性耕作机械的空间溢出效应在水稻主产区更明显,免耕机械的空间溢出效应在小麦主产区相对突出,而秸秆还田机械的空间溢出效应在三大粮食作物主产区基本无差异。为此,本研究提出加大保护性耕作推广力度、搭建农机服务信息化平台和提高保护性耕作农机装备水平的对策建议。

地球关键带土壤微生物介导有机碳转化研究进展

地球关键带是大气圈、生物圈、土壤圈、水圈、岩石圈高度交汇和相互作用的地球表层复杂系统,也是联结气候系统-地表过程-地球深部过程物质和能量循环的重要桥梁,微生物在地球关键带碳循环中扮演着重要角色,认识地球关键带结构与功能,阐明关键带土壤微生物介导的碳转化过程是当前关键带研究热点之一。本研究首先介绍地球关键带的结构与范畴,以及土壤微生物结构特征、微生物驱动的土壤碳循环研究进展;然后指出当前工作仍停留在地球关键带的基本结构认识和土壤碳储量特征描述上,建议从关键带整体框架出发,沿垂直方向综合考虑从植物冠层到基岩之间的碳循环过程,联合使用多种技术方法,将短期高频次观测和长期定位观测相结合,重视长时间尺度下土壤有机碳对全球变化和人类活动的响应及反馈机制,特别关注土壤碳在关键带各界面的微生物驱动过程及其迁移转化规律;最后在考虑地球大数据科学工程和全球碳排放路径等时代因素的背景下,开展大气、植被、土壤、微生物、基岩、地下水等多界面、多过程、多时间尺度的同步观测和系统性研究,为地球关键带土壤碳循环模型优化及气候变化预测提供科学依据,也为我国“双碳”目标提供理论支撑。

滇池螺类碳汇分布储存特征研究

通过形态学鉴定和容量法测定碳酸钙含量,运用IBM SPSS Statistics 26软件进行数据分析,并使用ArcGIS 10.2和Origin 2022软件进行绘图,探究滇池湖区螺类的碳汇效应大小和分布情况。结果表明:(1)螺蛳数量最多,占56.99%;其次为方格短沟蜷、蚌、钉螺滇川亚种;中国圆田螺和梨形环棱螺数量较少,占比不足1.00%。(2)不同螺类之间的形态特征具有明显差异,方格短沟蜷的壳体表面积最大且固碳能力最佳,平均碳含量为112.94 mg/g;其次是钉螺滇川亚种;蚌和螺蛳的碳含量相对较低,均值在70.00 mg/g左右。(3)除方格短沟蜷外,其他3种螺类的碳固存含量均与其壳高、壳宽及壳重呈负相关。滇池湖区的螺类碳汇大部分汇集于方格短沟蜷中,其次是数量最多的螺蛳。该研究结果可为滇池及其周边地区的碳储量评估和生态修复提供科学依据和参考。

南北过渡带常绿落叶阔叶混交林碳通量特征及其对环境因子的响应

森林生态系统强大的碳源/汇功能是实现“碳中和”和“碳达峰”战略目标最经济、有效的自然气候解决方案和固碳增汇手段。准确评估森林生态系统的碳汇能力,对于明确森林碳储量有重要意义。为明确亚热带-暖温带气候过渡带的常绿落叶阔叶混交林的碳通量特征及其驱动因素,2011—2020年利用涡度相关法开展了大别山常绿落叶阔叶混交林碳通量和环境要素的观测试验。结果表明:大别山常绿落叶阔叶混交林净生态系统CO_(2)交换量、生态系统呼吸(Reco)、总初级生态生产力分别为-788.13 gC m^(-2) a^(-1)、1074.14 gC m^(-2) a^(-1)、1862.27 gC m^(-2) a^(-1),该森林生态系统整体表现为碳汇,其固碳能力与相近纬度的常绿落叶阔叶混交林基本持平,并高于针阔叶混交林、毛竹林等其他类型的森林生态系统。10年间,大别山常绿落叶阔叶混交林的固碳能力有所增强。影响大别山常绿落叶阔叶混交林碳通量的主要环境因子为温度与太阳辐射,气温(Ta)、净辐射(Rn)、光合有效辐射和总辐射与生态系统碳生产力和GPP呈显著正相关(P<0.001),Reco与Ta和Rn呈显著正相关(P<0.001)。研究结果为气候变化响应敏感的南北气候过渡带森林生态系统的碳储量估算、碳循环过程模拟提供观测数据支持和科学依据。

CCER重启视角下林业碳汇参与碳市场研究

碳排放权交易市场(碳市场)是中国积极实施应对气候变化战略、落实“双碳”目标的重要载体和动力机制。从重启国家核证自愿减排(CCER)机制重启视角出发,系统回顾国内外学者对中国碳市场与林业碳汇的研究,对CCER重启对碳市场的影响进行深入探讨。作为CCER的主要组成部分,针对林业碳汇进入碳市场面临的问题进行重点研究。研究表明:①国内林业碳汇项目与市场机制具有多样性,包括林业碳汇CDM国际项目、CCER国家项目、地方林业碳汇项目。CCER是各碳排放权交易试点与全国碳市场重要的交易品种;②CCER进入全国碳市场,对于多元化发展碳金融市场有一定帮助,可以丰富碳金融产品种类,增加碳市场活跃度;③林业碳汇参与碳市场交易仍然存在方法学不成熟、制度约束、产权不明晰、交易风险等问题。针对上述问题,本文提出了完善碳汇交易制度的政策体系、明晰林业碳汇产权等建议。

“双碳”目标下新疆“三生”空间时空演变特征及碳效应

研究“双碳”目标下“三生”空间时空演变特征及碳效应,对干旱区生态经济可持续发展及实现国土空间绿色低碳发展有重要的实践意义。本文基于新疆土地利用遥感监测数据和能源消耗数据,运用“三生”空间动态度、转移矩阵及碳排放系数等方法,借助ArcGIS空间分析功能对新疆2000—2020年“三生”空间时空演变特征及碳效应进行分析。结果表明:(1)新疆近20 a“三生”空间综合动态度达0.11%,2005—2010年综合动态度最高。(2)20 a间“三生”空间总体上呈现生活生产空间急剧扩张,生态空间面积缩减的趋势。(3)生活生产空间是新疆最主要的碳排放空间类型,呈现出持续增长的趋势;生态生产空间对碳吸收的贡献率较大。研究结果可为构建符合新疆减排需求的“三生”空间分类体系提供科学支撑,对建设高质量“一带一路”,实现干旱区新疆低碳发展和“双碳”目标具有重要意义。

外源酸作用下流域岩石风化与碳汇效应--以漾弓江为例

流域岩石风化是重要的碳源/汇过程,也是全球碳循环中的重要环节。外源酸参与流域岩石风化,影响碳元素的地球化学循环和流域碳源/汇效应。漾弓江属长江上游金沙江水系,流域岩石风化过程和碳汇效应尚不清楚。在2023年旱季和雨季分别采集了漾弓江的干流和主要支流的水样品(地表水点9个、地下水点6个),对主要离子浓度进行检测,并利用水化学平衡法和Galy估算模型分析该流域的岩风化类型,估算了碳酸与硫酸共同作用下的岩石风化CO_(2)消耗量。结果表明:(1)漾弓江流域水系离子成分主要源于硅酸盐岩和碳酸盐岩风化,水化学类型为HCO_(3)-Ca型或HCO_(3)-Ca·Mg型。(2)硫酸和碳酸共同参与了漾弓江流域的岩石风化过程。在不考虑硫酸作用时,漾弓江流域岩石风化的大气CO_(2)消耗量为38.35 t CO_(2)·km^(−2)·a^(−1),而当考虑了硫酸参与时,岩石风化碳汇量降至25.54 t CO_(2)·km^(−2)·a^(−1),扣除约33%,大大提高了计算精度。(3)漾弓江流域岩石风化的大气CO_(2)消耗量为4.27×10^(4) t CO_(2)·a^(−1),是一个碳汇过程。硫酸参与流域岩石的风化改变了区域碳循环,这是全球碳循环模型不可忽略重要环节。

碳中和目标下中国海洋渔业碳汇能力及其空间效应研究

全球变暖问题日益引起国际社会的广泛关注,而实现碳中和目标的重要路径之一就是海洋渔业的固碳增汇能力,因此如何科学准确地测算海洋渔业碳汇能力并研究其空间效应对缓解全球气候变化尤为重要。论文根据2007—2021年中国9个沿海省份贝藻养殖面板数据,利用“可移出碳汇”模型对中国海洋渔业碳汇能力进行测算,并运用空间模型对其空间效应进行分析。研究结果显示:(1)中国海洋渔业碳汇能力时间上呈现整体上升态势、空间上表现分布不均的特征。(2)莫兰指数表明海洋渔业碳汇能力具有空间正相关性,但空间聚集程度具有不稳定性。(3)通过空间杜宾模型分解后得出海洋渔业养殖产量、科技投入、科技推广情况和渔业灾情直接效应为正,劳动力投入直接效应为负。从间接效应来看,海洋渔业发展水平、养殖产量、科技投入和科技推广情况间接效应为正,劳动力投入间接效应为负。因此,应综合考虑海洋渔业碳汇能力的空间关联性,为今后海洋渔业的发展制定科学合理的空间规划。

微塑料对红树林生态系统的影响研究进展

红树林生态系统是沿海生态系统中独特且重要的环境组成部分。然而,微塑料作为新型环境污染物通过不同方式进入红树林系统中,已经成为红树林面临的一项严重挑战。分析了微塑料对红树林生态系统的影响,总结了红树林生态系统中微塑料分布特征、微塑料对红树林生态系统的影响、红树林生态系统中微塑料分布影响因素、微塑料在红树林生态系统中的归宿,最后对红树林生态系统中微塑料的研究方向进行了展望。提出确立微塑料监测方法和检测标准、评估红树林中微塑料生态风险、建立微塑料污染治理和管理措施、微塑料模型预测、探索修复与去除策略和研究微塑料与海洋生态系统碳循环的相互作用6个研究,可为未来红树林微塑料领域研究重点和污染控制提供借鉴。

岩溶碳汇对气候和土地利用变化的响应研究--以湖北省恩施州为例

为研究气候和土地利用变化情况下岩溶碳汇通量的演变趋势及响应,基于CO_(2)通量全球侵蚀模型(global erosion model for CO_(2)fluxes,GEM-CO_(2))计算2000—2020年恩施州岩溶碳汇通量的时空动态变化,并分析气候和土地利用变化对岩溶碳汇通量的影响。结果表明:2000—2020年恩施州岩溶碳汇通量时空变化差异明显,在时间上呈现稳步上升的趋势,在空间上呈现“南高北低”的分布格局,岩溶碳汇通量多年平均值为3.87×10^(5) t/a;降水量与岩溶碳汇通量的变化为正相关,蒸发量与岩溶碳汇通量的变化为负相关;岩溶碳汇通量对不同时期土地利用变化的响应有所不同。该研究证实了碳酸盐岩风化作用所消耗的CO_(2)参与了全球碳循环,同时可为土地合理利用和固碳增汇措施的实施提供科学依据。