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雄溪河河岸带典型草本植物冬季温室气体排放评估
Assessment of Winter Greenhouse Gas Emissions from Typical Herbaceous Plants in Riparian Zone of Xiongxi River Based on Global Warming Potential (GWP)
河流河岸带的草本植物在冬季可能表现为碳源,对“碳中和”具有潜在的负面影响。传统研究主要针对单项温室气体,缺少对河岸带CO2、CH4、N2O等多种温室气体的综合评估。以雄溪河为例,选择南方河流河岸带3种常见的草本植物(麦冬、葱莲、狗牙根),采用LI-7810/7820温室气体通量分析仪,分析不同植物冬季的CO2、CH4、N2O通量特征,并基于全球变暖潜能值(GWP)模型,对不同植被的冬季温室气体排放状况进行综合评估。结果表明: ①综合考虑CO2、CH4、N2O这3种温室气体下,狗牙根区、麦冬区、葱莲区、裸地区的冬季GWP分别为3 817.77±249.24、3 963.31±265.66、6 876.89±536.17、8 653.71±756.08 mg/(m2∙d)。虽然4个区域均表现为碳源,但相比于裸地区,种植草本植物均有助于减少河岸带的冬季碳排放。②河岸带GWP的日变化规律为中午高、早晚低,主要影响因素为土壤温度。③使用GWP模型,能更好地评估不同温室气体的综合影响。从“碳中和”角度,建议选择狗牙根作为南方河流河岸带的主要草本植物。
[Objective] This study aims to explore the role of river riparian zones in southern China as sources or sinks of greenhouse gases during winter. Traditional studies often focus on individual greenhouse gases, lacking simultaneous observation and comprehensive assessment of multiple greenhouse gases such as CO2, CH4, and N2O. Therefore, the core objectives of this study are: (1) to quantify the winter fluxes of CO2, CH4, and N2O under three common riparian herbaceous plants (Ophiopogon japonicus, Allium tuberosum, and Cynodon dactylon) and in bare soil control plots; (2) to comprehensively assess the contribution of different vegetation types to the net winter greenhouse effect in riparian zones based on the global warming potential (GWP) model; (3) to identify the key environmental drivers affecting greenhouse gas fluxes; and (4) to provide a scientific basis for vegetation selection and ecological management in southern riparian zones from the practical perspective of promoting “carbon neutrality”. [Methods] This study took the riparian zone of the Xiongxi River, a typical river in southern China, as the study area. Three widely distributed and representative herbaceous plant communities, along with bare soil as control areas, were selected. Throughout the winter, on one sunny day in the middle of each month, high-precision LI-7810 and LI-7820 trace gas analyzers were used for in-situ simultaneous observations to obtain flux data for the three greenhouse gases. Meanwhile, key environmental parameters such as air temperature, soil temperature, and soil moisture were synchronously recorded. To integrate the overall impact of the three greenhouse gases on global warming, the global warming potential model was adopted. On a 100-year time scale, with CO2 as the reference, all fluxes were uniformly converted into CO2 equivalents, thereby obtaining the daily comprehensive GWP for each study area. Data analysis was conducted using statistical methods including one-way analysis of variance (ANOVA), Pearson correlation analysis, and regression analysis. [Results] Herbaceous plants significantly reduced the net carbon emissions in riparian zones during winter. After comprehensive assessment of CO2, CH4, and N2O, significant differences were found in winter GWP values across different areas. The average GWP in the Cynodon dactylon area, Ophiopogon japonicus area, Allium tuberosum area, and bare area was 3 817.77±249.24, 3 963.31± 265.66, 6 876.89±536.17,8 653.71±756.08 mg/(m2∙d), respectively. Although all areas functioned as net carbon sources during winter, the GWP was effectively reduced in the three herbaceous plant-covered areas compared to bare land. This result, for the first time, quantified the mitigation effect of herbaceous plants on the greenhouse effect of riparian zones under a winter, multi-gas comprehensive assessment framework. The impact of different vegetation types on greenhouse gas composition was species-specific. In-depth analysis of each gas component showed that CO2 emission fluxes in all vegetated areas were significantly lower than in bare land. CH4 fluxes mostly exhibited weak absorption, with the lowest average in bare areas and the highest in Ophiopogon japonicus areas. Regarding N2O flux, bare areas showed the highest average, while the Cynodon dactylon areas had the lowest. Observations also indicated a distinct diurnal variation in riparian GWP, with higher values at noon and lower values in the morning and evening. Pearson correlation analysis revealed that soil temperature was the key environmental factor driving this diurnal pattern, showing a highly significant positive correlation with the GWP value. This finding clarified the central role of temperature in regulating the carbon emission process of riparian zones in winter. [Conclusion] (1) This study overcomes the limitations of traditional single-gas studies, systematically revealing for the first time in southern China’s winter riparian environment that common herbaceous plants significantly and differentially influence regional net greenhouse effects by altering CO2, CH4, and N2O emission profiles. It confirms that vegetation cover in winter also has a certain emission-reduction function.(2) From the perspective of the synergy between riparian ecological engineering management and carbon neutrality goals, vegetation selection is crucial. Among the three plants examined in this study, Cynodon dactylon proves to be the optimal choice in winter due to its lowest GWP, whereas Allium tuberosum, though visually appealing, has the highest GWP and is therefore not recommended for planting from an emission-reduction perspective.(3) Soil temperature is the key environmental factor controlling the diurnal variation of winter greenhouse gas fluxes in riparian zones. This implies that under future global warming, rising winter temperatures may significantly enhance the carbon emission intensity of such ecosystems and should be fully considered in carbon cycle models.
河岸带 / 草本植物 / 温室气体通量 / 全球变暖潜能值(GWP)模型
riparian zone / herbaceous plants / greenhouse gas fluxes / global warming potential model
| [1] |
|
| [2] |
|
| [3] |
|
| [4] |
谢立勇, 许婧, 郭李萍, 等. 水肥管理对稻田CH4排放及其全球增温潜势影响的评估[J]. 中国生态农业学报, 2017, 25(7): 958-967.
(
|
| [5] |
|
| [6] |
王晶苑, 魏杰, 温学发. 土壤CO2通量梯度观测技术和方法的理论、假设与应用进展[J]. 植物生态学报, 2022, 46(12): 1523-1536.
土壤呼吸主要包括大气-土壤界面CO<sub>2</sub>释放量和土壤中CO<sub>2</sub>储存量变化两部分, 深入理解土壤CO<sub>2</sub>的产生和迁移过程是全面认识陆地生态系统碳循环的基础。通量梯度法是基于测量扩散驱动的CO<sub>2</sub>浓度梯度和扩散系数计算CO<sub>2</sub>通量的方法, 依据菲克第一定律可以计算出不同深度土壤CO<sub>2</sub>及其稳定碳同位素组成(δ<sup>13</sup>C)通量, 进而得到土壤CO<sub>2</sub>释放量和不同深度土壤CO<sub>2</sub>储存量。地下土壤CO<sub>2</sub>浓度(<sup>13</sup>CO<sub>2</sub>和<sup>12</sup>CO<sub>2</sub>浓度)主要受孔隙曲折度、根分布深度、微生物活性和土壤总CO<sub>2</sub>产生量控制。地下CO<sub>2</sub>传输过程受不同深度CO<sub>2</sub>浓度、孔隙度和含水量等的共同控制, 上述土壤理化性质和生物因素是土壤通量梯度法应用过程的关键影响因素, 直接决定了CO<sub>2</sub>及其δ<sup>13</sup>C通量计算的精度和准确度。通量梯度法是箱式法的有益补充, 可以明确不同深度土壤CO<sub>2</sub>产生和运移过程以及对土壤CO<sub>2</sub>释放量和储存量的影响, 阐明不同深度土壤对CO<sub>2</sub>排放的相对贡献, 揭示其环境和物理控制机制。
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Soil respiration is mainly composed of the CO2 released from atmosphere-soil interface and change of CO2 stored in the soil. Understanding the production and migration of CO2 in the soil is essential for measuring the carbon cycle in terrestrial ecosystems. The flux gradient method calculates soil CO2 flux by measuring the diffusion-driven CO2 concentration gradient and diffusion coefficient. The flux of soil CO2 and its stable carbon isotopes composition (δ13C) at different depths can be calculated based on Fickʼs law. The amount of CO2 released from soil and the amount of CO2 stored in different soil layers can thus be measured. The underground soil CO2 (13CO2 and 12CO2) concentration is mainly controlled by pore tortuosity, the depth of root distribution, microbial activity and total soil CO2 production. The underground CO2 transmission process is mainly controlled by the CO2 concentrations, porosity and water content at different depths of the soil. These physical, chemical and biological features of the soil are key factors affecting the application of the soil flux gradient method, and directly determine the precision and accuracy of soil CO2 and its δ13C flux calculation. The gradient method is a useful complement to the chamber method, which can clarify the process of production and migration of soil CO2 at different depths and thus the impacts on the release and storage of soil CO2, elucidating the contribution of soils at different depths to CO2 release and uncovering the underlying environmental and physical mechanisms. |
| [7] |
张若玉, 何金海, 张华. 温室气体全球增温潜能的研究进展[J]. 安徽农业科学, 2011, 39(28): 17416-17419, 17422.
(
|
| [8] |
|
| [9] |
IPCC. Climate Change 2021:The Physical Science Basis: Working Group I Contribution to the Sixth Assessment Report of the Intergovernmental Panel on Climate Change[M]. New York: Cambridge University Press, 2021.
|
| [10] |
李成伟, 刘章勇, 龚松玲, 等. 稻作模式改变对稻田CH4和N2O排放的影响[J]. 生态环境学报, 2022, 31(5):961-968.
长江中游稻作模式由传统中稻-冬季作物模式向再生稻发展的趋势明显,但关于稻作模式对稻田CH<sub>4</sub>和N<sub>2</sub>O排放的研究尚缺乏报道。以江汉平原3种模式为对象：稻-麦（RW）、稻-油（RR）和再生稻（Rr）,采用静态箱-气相色谱法,研究稻田CH<sub>4</sub>和N<sub>2</sub>O排放的变化规律,同时监测土壤硝态氮（NO<sup>3-</sup>-N）、铵态氮（NH<sub>4</sub><sup>+</sup>-N）、pH和土温的动态变化,以期揭示不同稻作模式对温室气体排放的影响及影响因素。结果表明,在非水稻季,RW、RR和Rr处理的CH<sub>4</sub>的累计排放量分别为6.34、9.35和8.63 kg∙hm<sup>-2</sup>,N<sub>2</sub>O平均排放通量分别为8.08、17.78和24.92 μg∙m<sup>-2</sup>∙h<sup>-1</sup>,表现为Rr>RR>RW;在水稻季,相比较RR处理,RW和Rr处理CH<sub>4</sub>的累计排放量分别增加了158.27%和148.38%,且差异显著,其N<sub>2</sub>O的累计排放量分别增加了34.89%和87.36%。Rr处理头季CH<sub>4</sub>的排放量占整个水稻季87.64%,其N<sub>2</sub>O平均排放通量头季要比再生季高35.99%。RW和Rr处理产量差异不显著,但要显著高于RR处理,其增幅分别为14.49%和24.40%。RR的全球增温潜势（GWP）和温室气体排放强度（GHGI）最低,其GWP比RW、Rr分别低45.05%和72.85%;GHGI分别降低了35.14%和63.64%。中稻季CH<sub>4</sub>的排放速率与NH<sub>4</sub><sup>+</sup>-N含量呈显著正相关（P<0.05）,Rr处理下CH<sub>4</sub>的排放量与NO<sub>3</sub><sup>-</sup>-N含量呈显著负相关关系（P<0.05）,与土壤pH呈负相关,且差异极显著（P<0.01）;中稻季N<sub>2</sub>O的排放与NO<sub>3</sub><sup>-</sup>-N和土温负相关,差异不显著（P>0.05）,Rr处理N<sub>2</sub>O排放与NH<sub>4</sub><sup>+</sup>-N呈显著正相关（P<0.05）。因此,在江汉平原稻-油模式不仅利用了冬闲田,提高作物种植产量,还有利于降低温室气体的排放,缓解全球增温潜势。
(
|
| [11] |
扆凡, 庞军柱, 刘岳坤, 等. 秦岭油松林不同坡位土壤CO2、CH4、N2O通量研究[J]. 环境科学学报, 2018, 38(6): 2506-2517.
(
|
| [12] |
刘硕, 李玉娥, 孙晓涵, 等. 温度和土壤含水量对温带森林土壤温室气体排放的影响[J]. 生态环境学报, 2013, 22(7):1093-1098.
(
|
| [13] |
After ecological restoration of high and steep slopes in the project disturbed area, soil properties, soil microorganisms, litter types and root types change with the succession of vegetation cover communities. However, the effects of different vegetation successional stages on soil respiration dynamics remain unclear. To elucidate trends and drivers of soil respiration in the context of vegetation succession, we used spatio-temporal alternative applied research. Vegetated concrete-restored slopes (VC) with predominantly herbaceous (GS), shrub (SS), and arborvitae (AS) vegetation were selected, and naturally restored slopes (NS) were used as control. SRS1000 T soil carbon flux measurement system was used to monitor soil respiration rate. The results showed that soil respiration (R) and fractions of all four treatments showed a single-peak curve, with peaks concentrated in July and August. During the succession of vegetation from herbaceous to arborvitae on VC slopes, R showed a decreasing trend, and GS was significantly higher than AS by 45%; Compared to NS, R was 29.81% and 21.56% higher in GS and SS successional stages, respectively, and 27.51% lower in AS stage. R was significantly and positively correlated with nitrate nitrogen (NO-N) and microbial biomass nitrogen (MBN), both of which are important factors in regulating R under vegetation succession. A bivariate model of soil temperature and water content explains the variability of Rs better. Overall, RS was higher than NS in the transition stage and lower than NS in the equilibrium stage of the vegetation community on VC slopes, and the R decreases gradually with the vegetation succession of artificial ecological restoration slopes.© 2024. The Author(s).
|
| [14] |
|
| [15] |
|
| [16] |
梅雪英. 城市草坪温室气体通量研究[D]. 上海: 华东师范大学, 2008.
(
|
| [17] |
C4 photosynthetic plants outperform C3 plants in hot and arid climates. By concentrating carbon dioxide around Rubisco C4 plants drastically reduce photorespiration. The frequency with which plants evolved C4 photosynthesis independently challenges researchers to unravel the genetic mechanisms underlying this convergent evolutionary switch. The conversion of C3 crops, such as rice, towards C4 photosynthesis is a long-standing goal. Nevertheless, at the present time, in the age of synthetic biology, this still remains a monumental task, partially because the C4 carbon-concentrating biochemical cycle spans two cell types and thus requires specialized anatomy. Here we review the advances in understanding the molecular basis and the evolution of the C4 trait, advances in the last decades that were driven by systems biology methods. In this review we emphasise essential genetic engineering tools needed to translate our theoretical knowledge into engineering approaches. With our current molecular understanding of the biochemical C4 pathway, we propose a simplified rational engineering model exclusively built with known C4 metabolic components. Moreover, we discuss an alternative approach to the progressing international engineering attempts that would combine targeted mutagenesis and directed evolution.© 2016 The Authors The Plant Journal © 2016 John Wiley & Sons Ltd.
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| [18] |
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| [19] |
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| [20] |
. Although greenhouse gas emissions during winter contribute significantly to annual balances, their quantification is still highly uncertain in snow-covered ecosystems. Here, carbon dioxide (CO2), methane (CH4) and nitrous oxide (N2O) fluxes were measured at a subalpine managed grassland in Switzerland using concentration gradients within the snowpack (CO2, CH4, N2O) and the eddy covariance method (CO2) during the winter 2010/2011. Our objectives were (1) to identify the temporal and spatial variation of greenhouse gases (GHGs) and their drivers, and (2) to estimate the GHG budget of the site during this specific season (1 December–31 March, 121 days). Mean winter fluxes (December–March) based on the gradient method were 0.77 ± 0.54 μmol m−2 s−1 for CO2 (1.19 ± 1.05 μmol m−2 s−1 measured by eddy covariance), −0.14 ± 0.09 nmol m−2 s−1 for CH4 and 0.23 ± 0.23 nmol m−2 s−1 for N2O, respectively. In comparison with the CO2 fluxes measured by eddy covariance, the gradient technique underestimated the effluxes by 50%. While CO2 and CH4 fluxes decreased with the progressing winter season, N2O fluxes did not follow a seasonal pattern. The major variables correlating with the fluxes of CO2 and CH4 were soil temperature and snow water equivalent, which is based on snow height and snow density. N2O fluxes were only explained poorly by any of the measured environmental variables. Spatial variability across the valley floor was smallest for CO2 and largest for N2O. During the winter season 2010/2011, greenhouse gas fluxes ranged between 550 ± 540 g CO2 m−2 estimated by the eddy covariance approach and 543 ± 247 g CO2 m−2, −0.4 ± 0.01 g CH4 m−2 and 0.11 ± 0.1 g N2O m−2 derived by the gradient technique. Total seasonal greenhouse gas emissions from the grassland were between 574 ± 276 and 581 ± 569 g CO2 eq. m−2, with N2O contributing 5% to the overall budget and CH4 reducing the budget by 0.1%. Cumulative budgets of CO2 were smaller than emissions reported for other subalpine meadows in the Swiss Alps and the Rocky Mountains. Further investigations on the GHG exchange of grasslands in winter are needed in order to (1) deepen our currently limited knowledge on the environmental drivers of each GHG, (2) to thoroughly constrain annual balances, and (3) to project possible changes in GHG flux magnitude with expected shorter and warmer winter periods.
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| [21] |
. A profound understanding of temporal and spatial variabilities of soil carbon dioxide (CO2), methane (CH4) and nitrous oxide (N2O) fluxes between terrestrial ecosystems and the atmosphere is needed to reliably quantify these fluxes and to develop future mitigation strategies. For managed grassland ecosystems, temporal and spatial variabilities of these three soil greenhouse gas (GHG) fluxes occur due to changes in environmental drivers as well as fertilizer applications, harvests and grazing. To assess how such changes affect soil GHG fluxes at Swiss grassland sites, we studied three sites along an altitudinal gradient that corresponds to a management gradient: from 400 m a.s.l. (intensively managed) to 1000 m a.s.l. (moderately intensive managed) to 2000 m a.s.l. (extensively managed). The alpine grassland was included to study both effects of extensive management on CH4 and N2O fluxes and the different climate regime occurring at this altitude. Temporal and spatial variabilities of soil GHG fluxes and environmental drivers on various timescales were determined along transects of 16 static soil chambers at each site. All three grasslands were N2O sources, with mean annual soil fluxes ranging from 0.15 to 1.28 nmol m−2 s−1. Contrastingly, all sites were weak CH4 sinks, with soil uptake rates ranging from −0.56 to −0.15 nmol m−2 s−1. Mean annual soil and plant respiration losses of CO2, measured with opaque chambers, ranged from 5.2 to 6.5 μmol m−2 s−1. While the environmental drivers and their respective explanatory power for soil N2O emissions differed considerably among the three grasslands (adjusted r2 ranging from 0.19 to 0.42), CH4 and CO2 soil fluxes were much better constrained (adjusted r2 ranging from 0.46 to 0.80) by soil water content and air temperature, respectively. Throughout the year, spatial heterogeneity was particularly high for soil N2O and CH4 fluxes. We found permanent hot spots for soil N2O emissions as well as locations of permanently lower soil CH4 uptake rates at the extensively managed alpine site. Including hot spots was essential to obtain a representative mean soil flux for the respective ecosystem. At the intensively managed grassland, management effects clearly dominated over effects of environmental drivers on soil N2O fluxes. For CO2 and CH4, the importance of management effects did depend on the status of the vegetation (LAI).
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