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大气CO2浓度升高与森林群落结构的可能性变化 总被引:6,自引:1,他引:5
大气CO2浓度升高的所引起的森林生态系统稳定性的变化会导致森林在结构和功能上的变动,概述了大气CO2浓度升高和陆地森林生态系统可能性变化之间的相互关系的研究情况。由于大气CO2浓度升高出现了额外多的C,供应,讨论了以这些额外多的C经大气-植物-土壤途径的流动走向,来研究大气CO2浓度的升高,与森林结构的相互作用,探讨了大气CO2浓度升高对森林植物生长、冠层结构、引发的生物量增量的分配、凋落物质量和 相似文献
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陆地土壤碳循环的研究动态 总被引:56,自引:3,他引:56
1 引 言陆地碳循环不仅关系到陆地生态系统生产力的形成,同时也影响到整个地球系统的能量平衡,是陆地生态系统结构和功能的综合体现。近几十年来,由于人类活动引起大气CO2浓度的急剧上升,并可能导致全球气候变化,而且这种变化与陆地碳循环之间存在复杂的相互反馈机制,陆地碳循环已成为生态学、气候学、土壤学、生理学及地质学等众多学科研究的共同目标。在国际地圈生物圈研究计划(IGBP)中,碳循环也是全球尺度模型化工作最初集中的主要目标[13]。然而由于陆地生态系统的多样性和复杂性,目前在陆地碳循环研究中仍存… 相似文献
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陆地碳循环研究中的模型方法 总被引:23,自引:3,他引:20
陆地碳循环是全球变化研究中的重要内容,碳循环模型已成为研究陆地碳循环的必要方法.其中气候变化、大气CO2浓度上升以及人类活动引起的土地利用和土地覆盖变化导致陆地生态系统在结构、功能、组成和分布等方面的变化及其反馈关系对陆地碳循环的影响是模型模拟的关键问题.生物地理模型和生物地球化学模型是碳循环模型的两大类型,建模方法、模型性质、特点和应用范围各异.碳循环模型的发展方向是综合两类模型的特点,建立全球动态碳循环模型. 相似文献
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CO2浓度升高对植物-土壤系统地下部分碳流通的影响 总被引:11,自引:1,他引:11
目前 ,由于化石燃料的燃烧和土地利用的改变 ,每年释放到大气中的碳大约有 7Gt[2 4 ] ,其中 ,有 3Gt留在大气中 ,2Gt被固定在深海中 ,另 2Gt被植物固定在生态系统中[19,4 8] ,事实上 ,陆地生态系统中的碳大部分都贮存在土壤中[4 4 ] ,所以植物与土壤之间的碳流通对全球碳循环极为重要。大气CO2 浓度升高有可能通过生态系统中的各种生理过程来改变植物 -土壤系统中碳通量的变化 ,使输入土壤的碳量增加 ,另一方面 ,地下部分碳通量的增加使土体成为一个潜在的碳汇 ,有可能缓解大气中CO2 浓度的升高。但有关高CO2 对地下部分植物… 相似文献
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稻田CH4和N2O的排放及养萍和施肥的影响 总被引:56,自引:10,他引:56
用箱法对我国东北稻田CH4和N2O排放进行观测研究表明,东北稻田的CH4排放通量比南方稻田小,平均日排放通量和生长季节排放总量分别为0.07和7.4g·m-2.稻田淹水期几乎没有N2O的净排放,但在非淹水期内却有大量N2O排放(平均通量59μgN2O·m-2·h-1).稻田养萍和施肥明显促进CH4和N2O排放.稻田CH4和N2O排放之间存在消长关系.制定稻田温室气体减排技术措施时应充分注意这一关系. 相似文献
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植物光合作用对大气CO2浓度升高的反应 总被引:78,自引:1,他引:78
近年来大气中CO2浓度急剧增加使人们重新对研究CO2浓度升高对植物光合作用影响感兴趣。预计在未来的100a中,大气CO2浓度还将不断增长并达到当今的2倍。CO2排放量的增加不仅加剧了地球上的温室效应,也将改变全球生态系统中碳的平衡。离浓度CO2对植物光剑作用的影响表现为短期和长期效应。短时间地供给高浓度CO2促进阿 光合作用,而长时间生长在高浓度CO2下抒使某些植物光合能力下降,出现了光合适应现象 相似文献
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尖峰岭热带山地雨林生态系统
碳平衡的初步研究 总被引:18,自引:0,他引:18
报道了我国海南岛目前保存面积较大、林分的组成和结构复杂的热带山地雨林生态系统的C素库和群落的CO2排放动态。通过在尖峰岭林区进行为期3a的研究,结果表明:热带山地雨林的碳素库主要有3个方面,即森林生物量中的C为234.3056t/hm2,森林凋落物现存量中的C为2.98t/hm2以及土壤层中的C为104.696t/hm2,合计为341.9816t/hm2。森林生态系统中的CO2平衡的基本动态为:每年用于群落总第一性生产力所同化的CO2总量为74.28t/hm2,其中42.69t/hm2的CO2又通过群落呼吸作用而释放出来,用于净第一性生产力为31.59t/hm2;另一方面,凋落物层每年通过呼吸而释放的CO2量为3.27t/hm2,土壤的释放(不包括根系的呼吸)量约为26.96t/hm2。收支相抵,热带山地雨林生态系统每年对大气中的CO2的固定量为1.366t/hm2,折合C为0.3725t/hm2。由此可见,恢复、发展和保护热带林生态系统是解决大气中CO2浓度升高、温室效应等全球性的生态问题的重要途径之一。 相似文献
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CO2 浓度升高对水稻根系分泌物的影响——总有机碳、甲酸和乙酸含量变化 总被引:34,自引:2,他引:32
在大气CO2浓度升高条件下采用水培方法对水稻根系生长及根系分泌物进行了初步研究,CO2浓度倍增对水培水稻的根系生长具有明显的促进作用,约为70%,但是根冠比却有所降低,水稻根系单位干重总有机碳,乙酸以及甲酸的释放量在CO2浓度倍增条件下变化不明显,但是单株奶系分泌物总量,乙酸以及甲酸的释放总量在CO2倍增处理下明显增加,推测水稻根系分泌物的增加是高浓度CO2下稻田CH4排放增加的重要原因之一。 相似文献
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CO_2倍增对植物生长和土壤微生物生物量碳、氮的影响 总被引:8,自引:0,他引:8
关于大气CO2浓度倍增(即为700μmolCO2·mol-1空气)将对植物生长产生诸多影响,已有大量报道[1,2]。但CO2倍增对植物及所在土壤中微生物影响的研究甚少[3,4]。土壤微生物是陆地生态系统中最活跃的成分,担负着分解动植物残体的重要作用,... 相似文献
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再生稻田温室气体排放特征及碳足迹 总被引:1,自引:0,他引:1
研究中国东南区域不同稻作方式对水稻生产过程中稻田温室气体排放特征及其碳足迹的影响,对促进水稻可持续生产有重要意义。本研究以当前推广的常规稻‘佳辐占'和杂交中稻‘甬优2640'为材料,构建4种适合福建不同生态类型区的稻作模式: 1) 双季稻,早稻和晚稻均种植佳辐占(D-J);2) 早熟再生稻,头季稻和再生季稻均种植佳辐占(R-J);3) 中熟再生稻,头季稻和再生季稻均种植甬优2640(R-Y);4) 单季晚稻,与中熟再生季稻同期抽穗的单季晚稻,种植甬优2640(S-Y)。采用密闭静态暗箱观测法和气相色谱法分别收集并检测稻田土壤温室气体排放量,借用生命周期法对不同稻作方式产生的直接和间接温室气体排放总量(即碳足迹)进行数据采集与比较分析。结果表明: 不同稻作方式稻田温室气体排放特征均表现为生育前期排放量较低,到孕穗期前后达到高峰后又下降,即全生育期呈前高后低的双峰曲线,其中早稻或头季稻达到的第1个峰值较相应晚稻或再生季稻的第2个峰值高。不同稻作模式稻田温室气体排放总量差异显著。各种植模式全球增温潜势(GWP)表现为:R-Y>D-J>S-Y>R-J,温室气体排放强度(GHGI)表现为:D-J>S-Y>R-Y>R-J;与双季稻模式相比,佳辐占再生稻模式GWP和GHGI分别降低26.1%和14.1%;与同期抽穗的单季晚稻相比,甬优2640再生季稻稻田GWP和GHGI分别降低74.3%和56.7%。不同稻作模式下水稻单位产量碳足迹为0.38~1.08 kg CO2-eq.·kg-1,其中双季稻模式下最高,再生稻模式下甬优2640的单位产量碳足迹最低。不同稻作模式产生的碳足迹主要来源于CH4,其贡献率高达44.2%~71.5%。可见,再生稻种植模式能显著降低水稻全球增温潜势和碳排放强度。选用高产低碳排放的水稻优良品种并配套科学栽培技术,是有效降低稻田CH4排放量和碳足迹、促进再生稻生产可持续发展的关键。 相似文献
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Climate change is likely to affect agroecosystems in many ways. This study was performed to investigate how a rice–winter wheat rotation agroecosystem in southeast China would respond to global warming. By using an infrared heater system, the soil surface temperature was maintained about 1.5 °C above ambient milieu over 3 years. In the third growing season (2009–2010), the evapotranspiration (ET) rate, crop production, soil respiration, and soil carbon pool were monitored. The ET rate was 23 % higher in the warmed plot as compared to the control plot during the rice paddy growing season, and the rice grain yield was 16.3 % lower, but there was no significant difference in these parameters between the plots during the winter wheat-growing season. The phenology of the winter wheat shifted under experimental warming, and ET may decrease late in the winter wheat-growing season. Experimental warming significantly enhanced soil respiration, with mean annual soil respiration rates of 2.57 ± 0.17 and 1.96 ± 0.06 μmol CO2 m?2 s?1 observed in the warmed and control plots, respectively. After 3 years of warming, a significant decrease in the total organic carbon was observed, but only in the surface soil (0–5 cm). Warming also stimulated the belowground biomass, which may have compensated for any heat-induced loss of soil organic carbon. Paddy rice seemed to be more vulnerable to warming than winter wheat in terms of water-use efficiency and grain production. 相似文献
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Takeshi Tokida Minaco Adachi Weiguo Cheng Yasuhiro Nakajima Tamon Fumoto Miwa Matsushima Hirofumi Nakamura Masumi Okada Ryoji Sameshima Toshihiro Hasegawa 《Global Change Biology》2011,17(11):3327-3337
Quantification of rhizodeposition (root exudates and root turnover) represents a major challenge for understanding the links between above‐ground assimilation and below‐ground anoxic decomposition of organic carbon in rice paddy ecosystems. Free‐air CO2 enrichment (FACE) fumigating depleted 13CO2 in rice paddy resulted in a smaller 13C/12C ratio in plant‐assimilated carbon, providing a unique measure by which we partitioned the sources of decomposed gases (CO2 and CH4) into current‐season photosynthates (new C) and soil organic matter (old C). In addition, we imposed a soil‐warming treatment nested within the CO2 treatments to assess whether the carbon source was sensitive to warming. Compared with the ambient CO2 treatment, the FACE treatment decreased the 13C/12C ratio not only in the rice‐plant carbon but also in the soil CO2 and CH4. The estimated new C contribution to dissolved CO2 was minor (ca. 20%) at the tillering stage, increased with rice growth and was about 50% from the panicle‐formation stage onwards. For CH4, the contribution of new C was greater than for heterotrophic CO2 production; ca. 40–60% of season‐total CH4 production originated from new C with a tendency toward even larger new C contribution with soil warming, presumably because enhanced root decay provided substrates for greater CH4 production. The results suggest a fast and close coupling between photosynthesis and anoxic decomposition in soil, and further indicate a positive feedback of global warming by enhanced CH4 emission through greater rhizodeposition. 相似文献
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日本长期不同施肥稻田N2O和CH4排放特征及其环境影响 总被引:4,自引:0,他引:4
观测了75年长期连续不施肥、施硫酸铵、施熟制水稻秸秆与豆饼混合堆肥、施绿肥苜蓿4种处理下日本单季稻田温室气体N2O和CH4的排放特征及其环境影响.结果表明: 在水稻生长季节,不同处理间N2O排放无显著差异,但CH4排放差异显著;长期连续施用有机肥虽然没有增加N2O排放却促进了CH4排放.各系统排放N2O和CH4所产生的累积全球增温潜势(GWP)以绿肥处理最大(310.7 g CO2e·m-2),熟制有机堆肥次之(151g CO2e·m-2),硫酸铵处理最小(60.6 g CO2e·m-2).稻田系统的GWP主要来自CH4排放,控制和减少稻田系统CH4排放是稻田温室气体减排的核心问题.长期连续施用熟制有机堆肥既能增加土壤有机质,改善地力,满足水稻高产,又能实现CH4减排,是实践中值得推荐的水稻生产模式. 相似文献
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观测了75年长期连续不施肥、施硫酸铵、施熟制水稻秸秆与豆饼混合堆肥、施绿肥苜蓿4种处理下日本单季稻田温室气体N2O和CH4的排放特征及其环境影响.结果表明: 在水稻生长季节,不同处理间N2O排放无显著差异,但CH4排放差异显著;长期连续施用有机肥虽然没有增加N2O排放却促进了CH4排放.各系统排放N2O和CH4所产生的累积全球增温潜势(GWP)以绿肥处理最大(310.7 g CO2e·m-2),熟制有机堆肥次之(151g CO2e·m-2),硫酸铵处理最小(60.6 g CO2e·m-2).稻田系统的GWP主要来自CH4排放,控制和减少稻田系统CH4排放是稻田温室气体减排的核心问题.长期连续施用熟制有机堆肥既能增加土壤有机质,改善地力,满足水稻高产,又能实现CH4减排,是实践中值得推荐的水稻生产模式. 相似文献
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Jun Cui Rongjuan Zhang Naishun Bu Huabin Zhang Boping Tang Zhaolei Li Lifeng Jiang Jiakuan Chen Changming Fang 《Journal of Plant Ecology》2013,6(3):240
Aims Although many studies have reported net gains of soil organic carbon (SOC) after afforestation on croplands, this is uncertain for Chinese paddy rice croplands. Here, we aimed to evaluate the effects of afforestation of paddy rice croplands on SOC sequestration and soil respiration (R s). Such knowledge would improve our understanding of the effectiveness of various land use options on greenhouse gas mitigation in China.Methods The investigation was conducted on the Chongming Island, north subtropical China. Field sites were reclaimed from coastal salt marshes in the 1960s, and soils were homogeneous with simple land use histories. SOC stocks and R s levels were monitored over one year in a paddy rice cropland, an evergreen and a deciduous broad-leaved plantation established on previous paddy fields and a reference fallow land site never cultivated. Laboratory incubation of soil under fast-changing temperatures was used to compare the temperature sensitivity (Q 10) of SOC decomposition across land uses.Important findings After 15–20 years of afforestation on paddy fields, SOC concentration only slightly increased at the depth of 0–5cm but decreased in deeper layers, which resulted in a net loss of SOC stock in the top 40cm. Seasonal increase of SOC was observed during the rice-growing period in croplands but not in afforested soils, suggesting a stronger SOC sequestration by paddy rice cropping. However, SOC sequestered under cropping was more labile, as indicated by its higher contents of dissolved organic carbon and microbial biomass. Also, paddy soils had higher annual R s than afforested soils; R s abruptly increased after paddy fields were drained and plowed and remained distinctively high throughout the dry farming period. Laboratory incubation revealed that paddy soils had a much higher Q 10 of SOC decomposition than afforested soils. Given that temperature was the primary controller of R s in this region, it was concluded that despite the stronger SOC sequestration by paddy rice cropping, its SOC was less stable than in afforested systems and might be more easily released into the atmosphere under global warming. 相似文献
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WILLIAM H. SCHLESINGER 《Global Change Biology》2010,16(2):849-850
Applications of fertilizer, often thought to enhance carbon sequestration in agricultural soils, are of no value to the mitigation of climate change if the carbon dioxide released during the production and distribution of nitrogen fertilizer exceeds the incremental carbon storage in soils from its use. Nitrogen fertilizer is also a source of the greenhouse gas nitrous oxide. The recent analysis of carbon sequestration in cropland soils of China does not apply these ‘discounts’ to the global warming mitigation expected from greater use of fertilizer; doing so would likely eliminate all the climate benefits of the postulated enhanced carbon sequestration. 相似文献
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Chenchao Xu Naifang Zhang Kaihang Zhang Shuyao Li Qing Xia Jing Xiao Maojun Liang Weilei Lei Junpan He Gaiping Chen Chengjun Ge Xunhua Zheng Jianguo Zhu Shuijin Hu Roger T. Koide Mary K. Firestone Lei Cheng 《Global Change Biology》2023,29(16):4670-4685
Continued current emissions of carbon dioxide (CO2) and methane (CH4) by human activities will increase global atmospheric CO2 and CH4 concentrations and surface temperature significantly. Fields of paddy rice, the most important form of anthropogenic wetlands, account for about 9% of anthropogenic sources of CH4. Elevated atmospheric CO2 may enhance CH4 production in rice paddies, potentially reinforcing the increase in atmospheric CH4. However, what is not known is whether and how elevated CO2 influences CH4 consumption under anoxic soil conditions in rice paddies, as the net emission of CH4 is a balance of methanogenesis and methanotrophy. In this study, we used a long-term free-air CO2 enrichment experiment to examine the impact of elevated CO2 on the transformation of CH4 in a paddy rice agroecosystem. We demonstrate that elevated CO2 substantially increased anaerobic oxidation of methane (AOM) coupled to manganese and/or iron oxides reduction in the calcareous paddy soil. We further show that elevated CO2 may stimulate the growth and metabolism of Candidatus Methanoperedens nitroreducens, which is actively involved in catalyzing AOM when coupled to metal reduction, mainly through enhancing the availability of soil CH4. These findings suggest that a thorough evaluation of climate-carbon cycle feedbacks may need to consider the coupling of methane and metal cycles in natural and agricultural wetlands under future climate change scenarios. 相似文献
19.
施硅对增温稻田CH4和N2O排放的影响 总被引:4,自引:0,他引:4
夜间增温幅度大于白天是气候变暖的显著特征。夜间增温影响水稻生产及CH4和N2O排放。硅是作物有益元素,施硅可提高产量,减少稻田CH4排放。增温或施硅单因子对稻田CH4和N2O排放影响已有报道,但二者耦合如何影响水稻生产及稻田CH4和N2O排放,尚不清楚。通过田间模拟试验,研究了夜间增温下施硅对水稻生长、产量及温室气体持续增温/冷却潜势和排放强度的影响。采用铝箔反光膜夜间(19:00-6:00)覆盖水稻冠层进行模拟夜间增温试验。增温设2水平,即常温对照(CK)和夜间增温(NW);施硅量设2水平,即Si0(不施硅)和Si1(钢渣硅肥,200 kgSiO2/ha)。结果表明,施硅可缓解夜间增温对水稻根系活力的抑制作用,降低夜间增温对水稻地上部、地下部干重和产量的抑制作用。夜间增温显著提高CH4累计排放量,而施硅显著降低CH4累计排放量。夜间增温下施硅处理稻田CH4累计排放量在分蘖期、拔节期、抽穗-扬花期和灌浆成熟期比未施硅处理分别低48.12%、49.16%、61.59%和39.13%。夜间增温或施硅均促进稻田N2O排放,夜间增温下施硅在上述生育期以及全生育期的累计排放量依次比对照高78.17%、51.45%、52.01%、26.14%和40.70%。研究认为,施硅可缓解夜间增温对稻田综合增温潜势和排放强度的促进作用。 相似文献
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作为全球变化的主要表现之一,气候变暖对全球陆地生态系统碳循环的影响巨大,揭示这一作用对于精确理解碳循环的过程和相关政策的制定具有重要的指导意义。该文综述了此领域近十几年来的主要研究工作,总结了陆地生态系统碳循环对气候变暖响应的主要内部机制及其过程,简述了相关模型的发展及其主要应用,并指出以往研究中存在的主要问题以及未来研究的主要方向。在气候变暖条件下,陆地生态系统碳循环的变化主要体现在以下几个方面:1)低纬度地区生态系统NPP一般表现为降低,而在中高纬度地区通常表现为增加,而在全球尺度上表现为NPP增加;2)土壤呼吸作用增强,但经过一段时间后表现出一定的适应性;3)高纬度地区的生态系统植被碳库表现为增加趋势,低纬度地区生态系统植被碳库变化不大,或略微降低,在全球尺度上表现为植被碳库增加;4)地表凋落物的产量和分解速率增加;5)土壤有机碳分解加速,进而减少土壤碳储存,同时植被碳库向土壤碳库的流动增加从而增加土壤碳库,这两种作用在不同生态系统的比重不同,在全球尺度上表现为土壤碳库的减少;6)尽管不同生态系统表现各异,总体上全球陆地生态系统表现为一个弱碳源。生物物理模型、生物地理模型和生物地球化学模型陆续被开发出来用于研究工作,并取得了一定的成果,但是研究结果仍然存在很大的不确定性。在未来的数年甚至是数十年间,气候变暖与全球变化的其它表现间的协同影响将是下一步的研究重点,气候变暖和陆地生态系统间的双向反馈作用机制是进行更准确研究的理论基础,生态系统结构和功能对气候变化的适应性是准确理解和预测未来气候情景下陆地生态系统碳循环的前提。 相似文献