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1.
A large interannual variation of biomass burning emissions from Southeast Asia is associated with the ENSO events. During 1997/98 and 1994 El Nino years, uncontrolled wildfires of tropical rainforests and peat lands in Indonesia were enlarged due to a long drought. Enhanced CO injection into the upper troposphere from the intense Indonesian fires was clearly observed in the 8-year measurements from a regular flask sampling over the western Pacific using a JAL airliner between Australia and Japan. This airliner observation also revealed that upper tropospheric CO2 cycle largely changed during the 1997 El Nino year due partly to the biomass burning emissions. Widespread pollution from the biomass burnings in Southeast Asia was simulated using a CO tracer driven by a 3D global chemical transport model. This simulation indicates that tropical deep convections connected to rapid advection by the subtropical jet play a significant role in dispersing biomass-burning emissions from Southeast Asia on a global scale. 相似文献
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《中国科学:生命科学英文版》2002,45(Z1):116-125
A large interannual variation of biomass burning emissions from Southeast Asia is associated with the ENSO events. During 1997/98 and 1994 El Niño years, uncontrolled wildfires of tropical rainforests and peat lands in Indonesia were enlarged due to a long drought. Enhanced CO injection into the upper troposphere from the intense Indonesian fires was clearly observed in the 8-year measurements from a regular flask sampling over the western Pacific using a JAL airliner between Australia and Japan. This airliner observation also revealed that upper tropospheric CO2 cycle largely changed during the 1997 El Niño year due partly to the biomass burning emissions. Widespread pollution from the biomass burnings in Southeast Asia was simulated using a CO tracer driven by a 3D global chemical transport model. This simulation indicates that tropical deep convections connected to rapid advection by the subtropical jet play a significant role in dispersing biomass-burning emissions from Southeast Asia on a global scale. 相似文献
3.
Spatial trends in pre-industrial biomass burning emissions for eastern North America were reconstructed from sediment charcoal data. Petrographic thin sections were prepared from varved lake sediments along a transect of sites extending from NW Minnesota eastward to NE Maine. Results showed an exponential decline in charcoal abundance with distance east from the prairie/forest border. This result quantifies burning along the broad climate/vegetation gradient from xeric woodland to mesic eastern deciduous forest. Post-settlement charcoal accumulation showed no such geographic pattern, varying from site-to-site, likely reflecting local variability in land use and combustion sources. Results suggest the total emissions of large (> 10 m diameter) charcoal particles decreased by a factor of three during the twentieth century. 相似文献
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David P. Turner Andrew R. Jacobson William D. Ritts Weile L. Wang Ramakrishna Nemani 《Global Change Biology》2013,19(11):3516-3528
Diagnostic carbon cycle models produce estimates of net ecosystem production (NEP, the balance of net primary production and heterotrophic respiration) by integrating information from (i) satellite‐based observations of land surface vegetation characteristics; (ii) distributed meteorological data; and (iii) eddy covariance flux tower observations of net ecosystem exchange (NEE) (used in model parameterization). However, a full bottom‐up accounting of NEE (the vertical carbon flux) that is suitable for integration with atmosphere‐based inversion modeling also includes emissions from decomposition/respiration of harvested forest and agricultural products, CO2 evasion from streams and rivers, and biomass burning. Here, we produce a daily time step NEE for North America for the year 2004 that includes NEP as well as the additional emissions. This NEE product was run in the forward mode through the CarbonTracker inversion setup to evaluate its consistency with CO2 concentration observations. The year 2004 was climatologically favorable for NEP over North America and the continental total was estimated at 1730 ± 370 TgC yr?1 (a carbon sink). Harvested product emissions (316 ± 80 TgC yr?1), river/stream evasion (158 ± 50 TgC yr?1), and fire emissions (142 ± 45 TgC yr?1) counteracted a large proportion (35%) of the NEP sink. Geographic areas with strong carbon sinks included Midwest US croplands, and forested regions of the Northeast, Southeast, and Pacific Northwest. The forward mode run with CarbonTracker produced good agreement between observed and simulated wintertime CO2 concentrations aggregated over eight measurement sites around North America, but overestimates of summertime concentrations that suggested an underestimation of summertime carbon uptake. As terrestrial NEP is the dominant offset to fossil fuel emission over North America, a good understanding of its spatial and temporal variation – as well as the fate of the carbon it sequesters ─ is needed for a comprehensive view of the carbon cycle. 相似文献
6.
GUIDO R. VAN DER WERF JAMES T. RANDERSON† G. JAMES COLLATZ‡ LOUIS GIGLIO§ 《Global Change Biology》2003,9(4):547-562
Global carbon emissions from fires are difficult to quantify and have the potential to influence interannual variability and long‐term trends in atmospheric CO2 concentrations. We used 4 years of Tropical Rainfall Measuring Mission (TRMM) Visible and Infrared Scanner (VIRS) satellite data and a biogeochemical model to assess spatial and temporal variability of carbon emissions from tropical fires. The TRMM satellite data extended between 38°N and 38°S and covered the period from 1998 to 2001. A relationship between TRMM fire counts and burned area was derived using estimates of burned area from other satellite fire products in Africa and Australia and reported burned areas from the United States. We modified the Carnegie‐Ames‐Stanford‐Approach (CASA) biogeochemical model to account for both direct combustion losses and the decomposition from fire‐induced mortality, using both TRMM and Sea‐viewing Wide Field of view Sensor (SeaWiFS) satellite data as model drivers. Over the 1998–2001 period, we estimated that the sum of carbon emissions from tropical fires and fuel wood use was 2.6 Pg C yr?1. An additional flux of 1.2 Pg C yr?1 was released indirectly, as a result of decomposition of vegetation killed by fire but not combusted. The sum of direct and indirect carbon losses from fires represented 9% of tropical and subtropical net primary production (NPP). We found that including fire processes in the tropics substantially alters the seasonal cycle of net biome production by shifting carbon losses to months with low soil moisture and low rates of soil microbial respiration. Consequently, accounting for fires increases growing season net flux by ~12% between 38°N and 38°S, with the greatest effect occurring in highly productive savanna regions. 相似文献
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The global pyrogenic carbon cycle and its impact on the level of atmospheric CO2 over past and future centuries
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The incomplete combustion of vegetation and dead organic matter by landscape fires creates recalcitrant pyrogenic carbon (PyC), which could be consequential for the global carbon budget if changes in fire regime, climate, and atmospheric CO2 were to substantially affect gains and losses of PyC on land and in oceans. Here, we included global PyC cycling in a coupled climate–carbon model to assess the role of PyC in historical and future simulations, accounting for uncertainties through five sets of parameter estimates. We obtained year‐2000 global stocks of (Central estimate, likely uncertainty range in parentheses) 86 (11–154), 47 (2–64), and 1129 (90–5892) Pg C for terrestrial residual PyC (RPyC), marine dissolved PyC, and marine particulate PyC, respectively. PyC cycling decreased atmospheric CO2 only slightly between 1751 and 2000 (by 0.8 Pg C for the Central estimate) as PyC‐related fluxes changed little over the period. For 2000 to 2300, we combined Representative Concentration Pathways (RCPs) 4.5 and 8.5 with stable or continuously increasing future fire frequencies. For the increasing future fire regime, the production of new RPyC generally outpaced the warming‐induced accelerated loss of existing RPyC, so that PyC cycling decreased atmospheric CO2 between 2000 and 2300 for most estimates (by 4–8 Pg C for Central). For the stable fire regime, however, PyC cycling usually increased atmospheric CO2 (by 1–9 Pg C for Central), and only the most extreme choice of parameters maximizing PyC production and minimizing PyC decomposition led to atmospheric CO2 decreases under RCPs 4.5 and 8.5 (by 5–8 Pg C). Our results suggest that PyC cycling will likely reduce the future increase in atmospheric CO2 if landscape fires become much more frequent; however, in the absence of a substantial increase in fire frequency, PyC cycling might contribute to, rather than mitigate, the future increase in atmospheric CO2. 相似文献
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YANG CHEN JAMES T. RANDERSON GUIDO R. VAN DER WERF DOUGLAS C. MORTON MINGQUAN MU PRASAD S. KASIBHATLA 《Global Change Biology》2010,16(7):2024-2038
We used satellite‐derived estimates of global fire emissions and a chemical transport model to estimate atmospheric nitrogen (N) fluxes from savanna and deforestation fires in tropical ecosystems. N emissions and reactive N deposition led to a net transport of N equatorward, from savannas and areas undergoing deforestation to tropical forests. Deposition of fire‐emitted N in savannas was only 26% of emissions – indicating a net export from this biome. On average, net N loss from fires (the sum of emissions and deposition) was equivalent to approximately 22% of biological N fixation (BNF) in savannas (4.0 kg N ha?1 yr?1) and 38% of BNF in ecosystems at the deforestation frontier (9.3 kg N ha?1 yr?1). Net N gains from fires occurred in interior tropical forests at a rate equivalent to 3% of their BNF (0.8 kg N ha?1 yr?1). This percentage was highest for African tropical forests in the Congo Basin (15%; 3.4 kg N ha?1 yr?1) owing to equatorward transport from frequently burning savannas north and south of the basin. These results provide evidence for cross‐biome atmospheric fluxes of N that may help to sustain productivity in some tropical forest ecosystems on millennial timescales. Anthropogenic fires associated with slash and burn agriculture and deforestation in the southern part of the Amazon Basin and across Southeast Asia have substantially increased N deposition in these regions in recent decades and may contribute to increased rates of carbon accumulation in secondary forests and other N‐limited ecosystems. 相似文献
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湿地土壤CO2通量研究进展 总被引:9,自引:1,他引:9
近年来 ,全球气候变化研究成为公众和科学界关注的热点之一 ,CO2 作为一种重要的温室气体 ,其源、汇及通量的研究得到格外重视。土壤作为一个巨大的碳库 (1 394× 10 18gC[15] ,是大气CO2 的重要的源或汇 ,其通量 (约 6 8± 4× 10 15gC·年 - 1)如此巨大 (燃料燃烧每年释放约 5 2× 10 15gC) [7,2 6 ] ,使得即使轻微的变化也会引起大气中的CO2 浓度的明显变化。精确测定各生态系统的土壤CO2 通量及其对全球变化的响应情况是十分重要的。土壤CO2 通量表现为土壤呼吸 ,这一术语初始的含义为一定时间内单位面积放出CO2 的… 相似文献
10.
The experimental data presented here relate to the question of whether terrestrial ecosystems will sequester more C in their soils, litter and biomass as atmospheric CO2 concentrations rise. Similar to our previous study with relatively fertile growth conditions (Körner and Arnone 1992), we constructed four rather nutrient-limited model communities of moist tropical plant species in greenhouses (approximately 7 m2 each). Plant communities were composed of seven species (77 individuals per community) representing major taxonomic groups and various life forms found in the moist tropics. Two ecosystems were exposed to 340 l CO2 l–1 and two to 610 l l–1 for 530 days of humid tropical growth conditions. In order to permit precise determination of C deposition in the soil, plant communities were initially established in C-free unwashed quartz sand. Soils were then amended with known amounts of organic matter (containing C and nutrients). Mineral nutrients were also supplied over the course of the experiment as timed-release full-balance fertilizer pellets. Soils represented by far the largest repositories for fixed C in all ecosystems. Almost 5 times more C (ca. 80% of net C fixation) was sequestered in the soil than in the biomass, but this did not differ between CO2 treatments. In addition, at the whole-ecosystem level we found a remarkably small and statistically non-significant increase in C sequestration (+4%; the sum of C accretion in the soil, biomass, litter and necromass). Total community biomass more than quadrupled during the experiment, but at harvest was, on average, only 8% greater (i.e. 6% per year; n.s.) under elevated CO2, mainly due to increased root biomass (+15%, P=0.12). Time courses of leaf area index of all ecosystems suggested that canopy expansion was approaching steady state by the time systems were harvested. Net primary productivity (NPP) of all ecosystems-i.e. annual accumulation of biomass, necromass, and leaf litter (but not plant-derived soil organic matter)-averaged 815 and 910 g m–2 year–1 at ambient and elevated CO2, respectively. These NPPs are remarkably similar to those of many natural moist tropical forested ecosystems. At the same time net productivity of soil organic matter reached 7000 g dry matter equivalent per m2 and year (i.e. 3500 g C m–2 year–1). Very slight yet statistically significant CO2-induced shifts in the abundance of groups of species occurred by the end of the experiment, with one group of species (Elettaria cardamomum, Ficus benjamina, F. pumila, Epipremnum pinnatum) gaining slightly, and another group (Ctenanthe lubbersiana, Heliconia humilis, Cecropia peltata) losing. Our results show that: (1) enormous amounts of C can be deposited in the ground which are normally not accounted for in estimates of NPP and net ecosystem productivity; (2) any enhancement of C sequestration under elevated atmospheric CO2 may be substantially smaller than is believed will occur (yet still very important), especially under growth conditions which permit close to natural NPP; and (3) species dominance in plant communities is likely to change under elevated CO2, but that changes may occur rather slowly. 相似文献
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秸秆还田量对土壤CO2释放和土壤微生物量的影响 总被引:33,自引:8,他引:33
对玉米季、小麦季3种不同秸秆还田量的土壤生物学指标的测定结果表明,在秸秆倍量还田中,随着秸秆量的增加,CO2释放量增加,而且倍量处理的增加量显著大于全量处理;在玉米和小麦季节中,不同量秸秆还田对土壤0~10和10~20cm的土壤微生物量的影响不同,但均能增大土壤微生物量,全量和倍量处理间没有明显差异、在土壤表层及下层,微生物量的最大值均落后于土壤呼吸的最大值,且土壤微生物量达到最大值即其最活跃状态后,下降缓慢,但土壤呼吸减少较快,说明微生物活动存在明显的合成性呼吸与维持性呼吸;综合评价不同秸秆量还田的效应,应采用秸秆全量还田,既能调节土壤物理环境,促进微生物的代谢活动,利于养分的转化,又可以减少环境污染。 相似文献
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用标准木回归分析法( 乔木、木质藤本) 和样方收获法( 灌木、草本) , 研究了西双版纳原始热带季节雨林生物量及其分配。雨林总生物量为692-590 t/hm2 , 其分配为: 乔木层占98-66 % 、灌木层占0-76 % 、木质藤本占0-50 % 、草本层占0-09 % , 生物量主要集中于乔木层。乔木层生物量的器官分配向树干和树根集中: 树干占69-80 % , 树根占21-56 % , 树枝占7-77 % ,树叶占0-77 % ; 生物量径级分配向中等径级(60 ~70 cm) 和最大径级(150 ~160 cm) 集中; 生物量垂直分配向上层集中; Ⅰ亚层( 高度> 40 m) 占60-55 % 、Ⅱ亚层(20 ~40 m) 占36-72 % 、Ⅲ亚层(3 ~20 m) 占2-73 % ; 优势种番龙眼生物量占乔木层的20-07 % ; 乔木层叶面积指数为6-91 。 相似文献
13.
不同干扰方式对疏叶骆驼刺形态特征及地上生物量的影响 总被引:2,自引:0,他引:2
以塔克拉玛干沙漠南缘策勒绿洲为研究区,研究了春季砍伐、秋季砍伐和春季火烧等干扰处理对绿洲-沙漠过渡带的自然植被疏叶骆驼刺形态特征及地上生物量的影响.结果表明:春季火烧降低了疏叶骆驼刺的株高、冠幅和生物量,不利于疏叶骆驼刺植被的恢复和再生;不同时间砍伐对疏叶骆驼刺植被恢复和再生的影响差异较大.春季砍伐使疏叶骆驼刺株高、冠幅和生物量降低,叶片生物量、刺的长度和直径增加.秋季砍伐使疏叶骆驼刺株高和冠幅降低,但分枝数量和生物量增加.秋季适度的砍伐有利于塔克拉玛干沙漠南缘疏叶骆驼刺的保护. 相似文献
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The climate,the fuel and the land use: Long‐term regional variability of biomass burning in boreal forests
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Chiara Molinari Veiko Lehsten Olivier Blarquez Christopher Carcaillet Basil A. S. Davis Jed O. Kaplan Jennifer Clear Richard H. W. Bradshaw 《Global Change Biology》2018,24(10):4929-4945
The influence of different drivers on changes in North American and European boreal forests biomass burning (BB) during the Holocene was investigated based on the following hypotheses: land use was important only in the southernmost regions, while elsewhere climate was the main driver modulated by changes in fuel type. BB was reconstructed by means of 88 sedimentary charcoal records divided into six different site clusters. A statistical approach was used to explore the relative contribution of (a) pollen‐based mean July/summer temperature and mean annual precipitation reconstructions, (b) an independent model‐based scenario of past land use (LU), and (c) pollen‐based reconstructions of plant functional types (PFTs) on BB. Our hypotheses were tested with: (a) a west‐east northern boreal sector with changing climatic conditions and a homogeneous vegetation, and (b) a north‐south European boreal sector characterized by gradual variation in both climate and vegetation composition. The processes driving BB in boreal forests varied from one region to another during the Holocene. However, general trends in boreal biomass burning were primarily controlled by changes in climate (mean annual precipitation in Alaska, northern Quebec, and northern Fennoscandia, and mean July/summer temperature in central Canada and central Fennoscandia) and, secondarily, by fuel composition (BB positively correlated with the presence of boreal needleleaf evergreen trees in Alaska and in central and southern Fennoscandia). Land use played only a marginal role. A modification towards less flammable tree species (by promoting deciduous stands over fire‐prone conifers) could contribute to reduce circumboreal wildfire risk in future warmer periods. 相似文献
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Andrew J. Cole Leonardo Mata Nicholas A. Paul Rocky de Nys 《Global Change Biology Bioenergy》2014,6(6):637-645
A major limiting factor in the development of algae as a feedstock for the bioenergy industry is the consistent production and supply of biomass. This study is the first to access the suitability of the freshwater macroalgal genus Oedogonium to supply biomass for bioenergy applications. Specifically, we quantified the effect of CO2 supplementation on the rate of biomass production, carbon capture, and feedstock quality of Oedogonium when cultured in large‐scale outdoor tanks. Oedogonium cultures maintained at a pH of 7.5 through the addition of CO2 resulted in biomass productivities of 8.33 (±0.51) g DW m?2 day?1, which was 2.5 times higher than controls which had an average productivity of 3.37 (±0.75) g DW m?2 day?1. Under these productivities, Oedogonium had a carbon content of 41–45% and a higher heating value of 18.5 MJ kg?1, making it an ideal biomass energy feedstock. The rate of carbon fixation was 1380 g C m?2 yr?1 and 1073.1 g C m?2 yr?1 for cultures maintained at a pH of 7.5 and 8.5, and 481 g C m?2 yr?1 for cultures not supplemented with CO2. This study highlights the potential of integrating the large‐scale culture of freshwater macroalgae with existing carbon waste streams, for example coal‐fired power stations, both as a tool for carbon sequestration and as an enhanced and sustainable source of bioenergy. 相似文献
17.
Marie Noël K. Djuikouo Jean‐Louis Doucet Charlemagne K. Nguembou Simon L. Lewis Bonaventure Sonké 《African Journal of Ecology》2010,48(4):1053-1063
We present tree community diversity, species composition, basal area and aboveground biomass of three forest types in the Dja Biosphere Reserve, in South‐East Cameroon, part of the contiguous tropical forest of the Congo Basin. A total of fourteen, 1 ha, plots were established in heterogeneous terra firme forests (TFF), Gilbertiodendron dewevrei forests (GDF) and periodically flooded forests (PFF). A total of 281 tree species with diameter ≥10 cm were recorded. The Shannon diversity index was significantly higher in TFF (5.7 ± 0.28) and PFF (5.6 ± 0.23) than in GDF (2.29 ± 0.48) (ANOVA, F2,11 = 139.75, P < 0.001). While tree density did not differ between forest types (F2,11 = 3.50, P = 0.06), basal area differed significantly (F2,11 = 7.38, P = 0.009), as did aboveground biomass (F2,11 = 17.95, P < 0.001). Mean AGB values were respectively, 596.1 ± 62.24, 401.67 ± 58.06 and 383.14 ± 61.91 Mg ha?1 in GDF, TFF and PFF. Variation in the abundance of trees with large diameter was the main reason for these differences. Few dominant species made the greatest contribution to the AGB. G. dewevrei, accounted for 83% of AGB in GDF, Penthaclethra macrophylla for 9.9% in TFF and Uapaca heudolotii for 10.6% in PFF. The importance of preserving G. dewevrei forest in the context of ‘Reducing Emissions from Deforestation and forest Degradation’ (REDD) policies is discussed. 相似文献
18.
马尾松林采伐迹地火烧黑炭对土壤活性碳氮库的影响 总被引:2,自引:0,他引:2
黑炭是火烧过程中不完全燃烧的产物,在火烧迹地的分布具有异质性。为了解黑炭输入量对土壤活性碳氮库的影响,选取中亚热带33年生马尾松人工林采伐迹地为研究对象,对比炼山1年后移除(B0)、单倍(B1)和双倍黑炭输入(B2)处理和未火烧对照土壤可溶性有机碳氮含量(DOC和DON)、矿质氮、土壤微生物量碳氮含量(MBC和MBN)之间的差异。结果表明:炼山对土壤DOC和DON含量的影响因土层而异,在0—10 cm土层,火烧土壤DOC和DON含量与对照土壤没有显著差异,而在10—20 cm土壤要显著低于对照土壤(P0.05)。火烧土壤矿质氮、土壤MBC和MBN含量均低于对照土壤,但差异未达到显著性水平(P0.05)。火烧土壤含水率、pH、全碳和全氮、铵态氮、土壤MBN含量均与黑炭输入量成正比,特别是在10—20 cm土层,B2处理土壤铵态氮含量显著高于B0和B1处理(P0.05)。对于土壤MBN,黑炭输入处理(B1和B2)火烧土壤MBN含量与对照土壤没有显著差异,而去除黑炭处理(B0)火烧土壤MBN含量则显著低于对照土壤(P0.05)。结果说明黑炭输入对火烧土壤的微生物群落恢复和N素保持具有积极意义,因此亚热带人工林管理过程中应重视黑炭的利用。 相似文献
19.
岷江上游亚高山林区老龄林地上生物量动态变化 总被引:2,自引:0,他引:2
中国川西亚高山森林中的天然林大部分为成过熟的老龄林,对其生物量动态研究有助于了解其碳储量的动态变化规律.利用全国森林资源连续清查的27个固定样地数据,基于地上各器官生物量与树干胸径(D)和树高(h)的异速生长方程,估算了岷江上游亚高林山老龄林地上生物量密度的动态变化特征及其时空变化规律.结果表明,(1)从1988~2002年期间,老龄林地上生物量密度净增量为(27.311±15.580)Mg·hm-2,平均每年增长率为(1.930±1.091 )Mg·hm-2·a-1,平均每年枯损率为(2 271±1.424)Mg·hm-2·a-1;(2)地上生物量变化受各径级保留木生长量、枯损量及进界生长量影响,其中20~40cm径级保留木生长量与生物量净增量最大,>80cm径级生物量增量最小,40~60cm和60~80cm径级生物量在调查期间净增量出现负增长.(3)岷江上游老龄林地上生物量动态变化具有时空异质性,同一样地在不同调查间隔期或同一调查期间不同样地间生物量变化不同,不仅有增量数值大小差异,还表现为生物量增量的正负差异. 相似文献
20.
Aboveground biomass dynamics of subalpine old-growth forest in the upper reach of the Minjiang River
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Biomass estimation of old-growth forests in the upper Minjiang River (UMR) is important in quantifying carbon (C) sequestration and C sink size because majority of the natural forests in UMR are mature or over-mature. Based on the forest resource data from 27 fixed sampling plots that have been surveyed consecutively, the dynamics of the aboveground biomass density (AGBD) were characterized by the allometric relationships, and the space-time variations of the C sink size in the sub-alpine old-growth forests of UMR were explored. Our results showed that 1) the net increase in AGBD was (27.311 ± 15.580) Mg·hm?2 and the mean annual growth rate and mean annual death rate were (1.930 ± 1.091) and (2.271 ± 1.424) Mg·hm?2·a?1 during 1988–2002, respectively. 2) The aboveground biomass (AGB) largely depended on the growth and death rates of the trees with different diameters at the breast height (DBH) classes and the recruitment rate from one DBH class to another as well. The largest increment component of AGB came from the DBH class of 20 to 40 cm, whereas the minimum increment component of AGB was above 80 cm in DBH. The net negative increment of AGB occurred at DBH classes of 40–60 and 60–80 cm. 3) There were space-time variations of AGB in the alpine old-growth forests, indicated by AGB changing over time in the same sampling plot and varying among the locations or plots during the same sampling period. These variations were not only reflected in numerical value but also in positive or negative biomass increment. 相似文献