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1.
CAROLINE ROELANDT NICOLAS DENDONCKER MARK ROUNSEVELL DOMINIQUE PERRIN† BAS VAN WESEMAEL 《Global Change Biology》2007,13(1):18-27
This study analyses the spatial and temporal variability of N2O emissions from the agricultural soils of Belgium. Annual N2O emission rates are estimated with two statistical models, MCROPS and MGRASS, which take account of the impact of changes in land use, climate, and nitrogen‐fertilization rate. The models are used to simulate the temporal trend of N2O emissions between 1990 and 2050 for a 10′ latitude and longitude grid. The results are also aggregated to the regional and national scale to facilitate comparison with other studies and national inventories. Changes in climate and land use are derived from the quantitative scenarios developed by the ATEAM project based on the Intergovernmental Panel on Climate Change‐Special Report on Emissions Scenarios (IPCC‐SRES) storylines. The average N2O flux for Belgium was estimated to be 8.6 × 106 kg N2O‐N yr−1 (STD = 2.1 × 106 kg N2O‐N yr−1) for the period 1990–2000. Fluxes estimated for a single year (1996) give a reasonable agreement with published results at the national and regional scales for the same year. The scenario‐based simulations of future N2O emissions show the strong influence of land‐use change. The scenarios A1FI, B1 and B2 produce similar results between 2001 and 2050 with a national emission rate in 2050 of 11.9 × 106 kg N2O‐N yr−1. The A2 scenario, however, is very sensitive to the reduction in agricultural land areas (−14% compared with the 1990 baseline), which results in a reduced emission rate in 2050 of 8.3 × 106 kg N2O‐N yr−1. Neither the climatic change scenarios nor the reduction in nitrogen fertilization rate could explain these results leading to the conclusion that N2O emissions from Belgian agricultural soils will be more markedly affected by changes in agricultural land areas. 相似文献
2.
Spatially explicit estimates of N2O emissions from croplands suggest climate mitigation opportunities from improved fertilizer management 下载免费PDF全文
James S. Gerber Kimberly M. Carlson David Makowski Nathaniel D. Mueller Iñaki Garcia de Cortazar‐Atauri Petr Havlík Mario Herrero Marie Launay Christine S. O'Connell Pete Smith Paul C. West 《Global Change Biology》2016,22(10):3383-3394
With increasing nitrogen (N) application to croplands required to support growing food demand, mitigating N2O emissions from agricultural soils is a global challenge. National greenhouse gas emissions accounting typically estimates N2O emissions at the country scale by aggregating all crops, under the assumption that N2O emissions are linearly related to N application. However, field studies and meta‐analyses indicate a nonlinear relationship, in which N2O emissions are relatively greater at higher N application rates. Here, we apply a super‐linear emissions response model to crop‐specific, spatially explicit synthetic N fertilizer and manure N inputs to provide subnational accounting of global N2O emissions from croplands. We estimate 0.66 Tg of N2O‐N direct global emissions circa 2000, with 50% of emissions concentrated in 13% of harvested area. Compared to estimates from the IPCC Tier 1 linear model, our updated N2O emissions range from 20% to 40% lower throughout sub‐Saharan Africa and Eastern Europe, to >120% greater in some Western European countries. At low N application rates, the weak nonlinear response of N2O emissions suggests that relatively large increases in N fertilizer application would generate relatively small increases in N2O emissions. As aggregated fertilizer data generate underestimation bias in nonlinear models, high‐resolution N application data are critical to support accurate N2O emissions estimates. 相似文献
3.
William Burchill Dejun Li Gary J. Lanigan Micheal Williams James Humphreys 《Global Change Biology》2014,20(10):3137-3146
Nitrous oxide (N2O) emissions are subject to intra‐ and interannual variation due to changes in weather and management. This creates significant uncertainties when quantifying estimates of annual N2O emissions from grazed grasslands. Despite these uncertainties, the majority of studies are short‐term in nature (<1 year) and as a consequence, there is a lack of data on interannual variation in N2O emissions. The objectives of this study were to (i) quantify annual N2O emissions and (ii) assess the causes of interannual variation in emissions from grazed perennial ryegrass/white clover grassland. Nitrous oxide emissions were measured from fertilized and grazed perennial ryegrass/white clover grassland (WC) and from perennial ryegrass plots that were not grazed and did not receive N input (GB), over 4 years from 2008 to 2012 in Ireland (52°51′N, 08°21′W). The annual N2O‐N emissions (kg ha?1; mean ± SE) ranged from 4.4 ± 0.2 to 34.4 ± 5.5 from WC and from 1.7 ± 0.8 to 6.3 ± 1.2 from GB. Interannual variation in N2O emissions was attributed to differences in annual rainfall, monthly (December) soil temperatures and variation in N input. Such substantial interannual variation in N2O emissions highlights the need for long‐term studies of emissions from managed pastoral systems. 相似文献
4.
Climate- and crop-responsive emission factors significantly alter estimates of current and future nitrous oxide emissions from fertilizer use 总被引:1,自引:0,他引:1
Helen C. Flynn Jo Smith Keith A. Smith† Jim Wright† Pete Smith Jon Massheder‡ 《Global Change Biology》2005,11(9):1522-1536
The current Intergovernmental Panel on Climate Change (IPCC) default methodology (tier 1) for calculating nitrous oxide (N2O) emissions from nitrogen applied to agricultural soils takes no account of either crop type or climatic conditions. As a result, the methodology omits factors that are crucial in determining current emissions, and has no mechanism to assess the potential impact of future climate and land‐use change. Scotland is used as a case study to illustrate the development of a new methodology, which retains the simple structure of the IPCC tier 1 methodology, but incorporates crop‐ and climate‐dependent emission factors (EFs). It also includes a factor to account for the effect of soil compaction because of trampling by grazing animals. These factors are based on recent field studies in Scotland and elsewhere in the UK. Under current conditions, the new methodology produces significantly higher estimates of annual N2O emissions than the IPCC default methodology, almost entirely because of the increased contribution of grazed pasture. Total emissions from applied fertilizer and N deposited by grazing animals are estimated at 10 662 t N2O‐N yr?1 using the newly derived EFs, as opposed to 6 796 t N2O‐N yr?1 using the IPCC default EFs. On a spatial basis, emission levels are closer to those calculated using field observations and detailed soil modelling than to estimates made using the IPCC default methodology. This can be illustrated by parts of the western Ayrshire basin, which have previously been calculated to emit 8–9 kg N2O‐N ha?1 yr?1 and are estimated here as 6.25–8.75 kg N2O‐N ha?1 yr?1, while the IPCC default methodology gives a maximum emission level of only 3.75 kg N2O‐N ha?1 yr?1 for the whole area. The new methodology is also applied in conjunction with scenarios for future climate‐ and land‐use patterns, to assess how these emissions may change in the future. The results suggest that by 2080, Scottish N2O emissions may increase by up to 14%, depending on the climate scenario, if fertilizer and land management practices remain unchanged. Reductions in agricultural land use, however, have the potential to mitigate these increases and, depending on the replacement land use, may even reduce emissions to below current levels. 相似文献
5.
Xiaohan Wang Yu'e Li Muhammad Ahmed Waqas Bin Wang Waseem Hassan Xiaobo Qin 《Oikos》2021,130(9):1440-1449
Understanding the responses of soil nitrous oxide (N2O) emissions from terrestrial ecosystems to future CO2 enrichment and warming is critical for the development of mitigation and adaptation policies. The effects of continuous increase in elevated CO2 (EC) and elevated temperature (ET) on N2O emissions are not fully known. We synthesized 209 measurements from 70 published studies and carried out a meta-analysis to examine individual and interactive effects of EC and ET on N2O emissions from grasslands, croplands and forests. On average, a significant increase of 23% in N2O emissions was observed under EC across all case studies. EC did not affect N2O emissions from grasslands or forests, but significantly increased N2O emissions in croplands by 38%. The extent of ET effects on N2O emissions was nonsignificant and there was no significant difference in N2O emission responses among these three terrestrial systems. ET only promoted N2O emissions in forest by about 32% when ET was less than 2°C. The interactive effect of EC and ET on N2O emissions was significantly synergistic, showing a greater increase than the sum of the effects caused by EC and ET alone. Our findings indicated that the combination of EC and ET substantially promoted soil N2O and highlighted the urgent need to explore its mechanisms to better understand N2O responses under future climate change. 相似文献
6.
JIANWEN ZOU YAO HUANG† YANMEI QIN SHUWEI LIU QIRONG SHEN GENXING PAN YANYU LU‡ QIAOHUI LIU§ 《Global Change Biology》2009,15(1):229-242
Nitrogen fertilizer‐induced direct nitrous oxide (N2O) emissions depend on water regimes in paddy fields, such as seasonal continuous flooding (F), flooding–midseason drainage–reflooding (F‐D‐F), and flooding–midseason drainage–reflooding–moist intermittent irrigation but without water logging (F‐D‐F‐M). In order to estimate the changes in direct N2O emission from paddy fields during the rice‐growing season in Mainland of China between the 1950s and the 1990s, the country‐specific emission factors of N2O‐N under different water regimes combined with rice production data were adopted in the present study. Census statistics on rice production showed that water management and nitrogen input regimes have changed in rice paddies since the 1950s. During the 1950s–1970s, about 20–25% of the rice paddy was continuously waterlogged, and 75–80% under the water regime of F‐D‐F. Since the 1980s, about 12–16%, 77%, and 7–12% of paddy fields were under the water regimes of F, F‐D‐F, and F‐D‐F‐M, respectively. Total nitrogen input during the rice‐growing season has increased from 87.5 kg N ha−1 in the 1950s to 224.6 kg N ha−1 in the 1990s. The emission factors of N2O‐N were estimated to be 0.02%, 0.42%, and 0.73% for rice paddies under the F, F‐D‐F, and F‐D‐F‐M water regimes, respectively. Seasonal N2O emissions have increased from 9.6 Gg N2O‐N each year in the 1950s to 32.3 Gg N2O‐N in the 1990s, which is accompanied by the increase in rice yield over the period 1950s–1990s. The uncertainties in N2O estimate were estimated to be 59.8% in the 1950s and 37.5% in the 1990s. In the 1990s, N2O emissions during the rice‐growing season accounted for 8–11% of the reported annual total of N2O emissions from croplands in China, suggesting that paddy rice development could have contributed to mitigating agricultural N2O emissions in the past decades. However, seasonal N2O emissions would be increased, given that saving‐water irrigation and nitrogen inputs are increasingly adopted in rice paddies in China. 相似文献
7.
Controls and models for estimating direct nitrous oxide emissions from temperate and sub-boreal agricultural mineral soils in Europe 总被引:1,自引:1,他引:0
Based on a review of N2O field studies in Europe, major soil, climate and management controls of N2O release from agricultural mineral soils in the European Union have been identified. Data for these N2O emission drivers can easily be gathered from statistical services. Using stepwise multivariate linear regression analysis, empirical first order models of N2O emissions have been established which allow – in contrast to existing large-scale approaches – a regionally disaggregated estimation of N2O emissions at sub-national, national and continental level in the temperate and boreal climate regions of Europe. Arable soils showed lower mean and maximum emissions in oceanic temperate climate (Temperate West) than in pre-alpine temperate and sub-boreal climate (Sub-boreal Europe). Therefore, two separate regression models were developed. Nitrous oxide emissions from arable soils the Temperate West amount to an average flux rate below 2 kg N2O-N ha–1 yr–1 and rarely exceed 5 kg N2O-N ha–1 yr–1. They are modelled by the parameters fertiliser, topsoil organic carbon and sand content. In Sub-boreal European arable soils, N2O emissions vary in a much wider range between 0 and 27 kg N2O-N ha–1 yr–1 in dependence of available nitrogen, represented in the model by fertiliser and topsoil nitrogen content. Compared to existing methods for large scale inventories, the regression models allow a better regional fit to measured values since they integrate additional driving forces for N2O emissions. For grasslands, a fertiliser-based model was established which yields higher emission estimates than existing ones. Due to an extreme variability, no climate, soil nor management parameters could be included in the empirical grasslands model. 相似文献
8.
Linfeng Li Zhenzhen Zheng Weijin Wang Joel A. Biederman Xingliang Xu Qinwei Ran Ruyan Qian Cong Xu Biao Zhang Fang Wang Shutong Zhou Lizhen Cui Rongxiao Che Yanbin Hao Xiaoyong Cui Zhihong Xu Yanfen Wang 《Global Change Biology》2020,26(2):931-943
Nitrous oxide (N2O) emissions from soil contribute to global warming and are in turn substantially affected by climate change. However, climate change impacts on N2O production across terrestrial ecosystems remain poorly understood. Here, we synthesized 46 published studies of N2O fluxes and relevant soil functional genes (SFGs, that is, archaeal amoA, bacterial amoA, nosZ, narG, nirK and nirS) to assess their responses to increased temperature, increased or decreased precipitation amounts, and prolonged drought (no change in total precipitation but increase in precipitation intervals) in terrestrial ecosystem (i.e. grasslands, forests, shrublands, tundra and croplands). Across the data set, temperature increased N2O emissions by 33%. However, the effects were highly variable across biomes, with strongest temperature responses in shrublands, variable responses in forests and negative responses in tundra. The warming methods employed also influenced the effects of temperature on N2O emissions (most effectively induced by open‐top chambers). Whole‐day or whole‐year warming treatment significantly enhanced N2O emissions, but daytime, nighttime or short‐season warming did not have significant effects. Regardless of biome, treatment method and season, increased precipitation promoted N2O emission by an average of 55%, while decreased precipitation suppressed N2O emission by 31%, predominantly driven by changes in soil moisture. The effect size of precipitation changes on nirS and nosZ showed a U‐shape relationship with soil moisture; further insight into biotic mechanisms underlying N2O emission response to climate change remain limited by data availability, underlying a need for studies that report SFG. Our findings indicate that climate change substantially affects N2O emission and highlights the urgent need to incorporate this strong feedback into most climate models for convincing projection of future climate change. 相似文献
9.
Nitrous oxide (N2O) is a potent greenhouse gas with a high contribution from agricultural soils and emissions that depend on soil type, climate,
crops and management practices. The N2O emissions therefore need to be included as an integral part of environmental assessments of agricultural production systems.
An algorithm for N2O production and emission from agricultural soils was developed and included in the FASSET whole-farm model. The model simulated
carbon and nitrogen (N) turnover on a daily basis. Both nitrification and denitrification was included in the model as sources
for N2O production, and the N2O emissions depended on soil microbial and physical conditions. The model was tested on experimental data of N2O emissions from grasslands in UK, Finland and Denmark, differing in climatic conditions, soil properties and management.
The model simulated the general time course of N2O emissions and captured the observed effects of fertiliser and manure management on emissions. Scenario analyses for grazed
and cut grasslands were conducted to evaluate the effects of soil texture, climatic conditions, grassland management and N
fertilisation on N2O emissions. The soils varied from coarse sand to sandy loam and the climatic variation was taken to represent the climatic
variation within Denmark. N fertiliser rates were varied from 0 to 500 kg N ha−1. The simulated N2O emissions showed a non-linear response to increasing N rates with increasing emission factors at higher N rates. The simulated
emissions increased with increasing soil clay contents. N2O emissions were slightly increased at higher temperatures, whereas increasing annual rainfall generally lead to decreasing
emissions. Emissions were slightly higher from grazed grasslands compared with cut grasslands at similar rates of total N
input (fertiliser and animal excreta). The results indicate higher emission factors and thus higher potentials for reducing
N2O emissions for intensively grazed grasslands on fine textured soils than for extensive cut-based grasslands on sandy soils. 相似文献
10.
Katja Walter Axel Don Roland Fuß Jürgen Kern Julia Drewer Heinz Flessa 《Global Change Biology Bioenergy》2015,7(6):1260-1271
Oilseed rape is one of the leading feedstocks for biofuel production in Europe. The climate change mitigation effect of rape methyl ester (RME) is particularly challenged by the greenhouse gas (GHG) emissions during crop production, mainly as nitrous oxide (N2O) from soils. Oilseed rape requires high nitrogen fertilization and crop residues are rich in nitrogen, both potentially causing enhanced N2O emissions. However, GHG emissions of oilseed rape production are often estimated using emission factors that account for crop‐type specifics only with respect to crop residues. This meta‐analysis therefore aimed to assess annual N2O emissions from winter oilseed rape, to compare them to those of cereals and to explore the underlying reasons for differences. For the identification of the most important factors, linear mixed effects models were fitted with 43 N2O emission data points deriving from 12 different field sites. N2O emissions increased exponentially with N‐fertilization rates, but interyear and site‐specific variability were high and climate variables or soil parameters did not improve the prediction model. Annual N2O emissions from winter oilseed rape were 22% higher than those from winter cereals fertilized at the same rate. At a common fertilization rate of 200 kg N ha?1 yr?1, the mean fraction of fertilizer N that was lost as N2O‐N was 1.27% for oilseed rape compared to 1.04% for cereals. The risk of high yield‐scaled N2O emissions increased after a critical N surplus of about 80 kg N ha?1 yr?1. The difference in N2O emissions between oilseed rape and cereal cultivation was especially high after harvest due to the high N contents in oilseed rape's crop residues. However, annual N2O emissions of winter oilseed rape were still lower than predicted by the Stehfest and Bouwman model. Hence, the assignment of oilseed rape to the crop‐type classes of cereals or other crops should be reconsidered. 相似文献
11.
Effect of improved nitrogen management on greenhouse gas emissions from intensive dairy systems in the Netherlands 总被引:1,自引:0,他引:1
R. L. M. SCHILS A. VERHAGEN H. F. M. AARTS P. J. KUIKMAN† L. B. J. EBEK‡ 《Global Change Biology》2006,12(2):382-391
Dairy systems in Europe contribute to the emissions of the greenhouse gases (GHGs) nitrous oxide (N2O), methane (CH4) and carbon dioxide (CO2). In this paper, the effects of improved nitrogen (N) management on GHG emissions from Dutch dairy farms are determined. The GHG emissions are calculated using the panel on climate change (IPCC) methodology for the Netherlands, an updated and refined IPCC methodology, and a full accounting approach. The changes in dairy farming over the last 20 years, and the consequences for N management are described using detailed farm‐level data, collected in 1985, 1997 and 2002. The selected years represent distinct stages in the implementation of N policies. The changes in N management have reduced the GHG emissions. A reduction of the N surplus per kilogram milk with 1 g N reduced the GHG emissions per kilogram milk with approximately 29 g CO2‐equivalents. The reduction of the N surpluses was mainly brought about by reduced fertilizer use and reduced grazing time. The use of updated and refined emission factors resulted in higher CH4 emissions and lower N2O emissions. On average, the overall emission was 36% higher with the refined method. Full accounting, including all direct and indirect emissions of CH4, N2O and CO2, increased the emission with 36% compared with the refined IPCC methodology. We conclude that the N surplus at farm level is a useful indicator of GHG emissions. A full accounting system as presented in this study may effectively enable farmers to address the issue of emissions of GHGs in their operational management decisions. Both approaches serve their own specific objectives: full accounting at the farm level to explore mitigation options, and the IPCC methods to report changes in GHG emissions at the national level. 相似文献
12.
LOUISE BARTON KLAUS BUTTERBACH‐BAHL RALF KIESE DANIEL V. MURPHY 《Global Change Biology》2011,17(2):1153-1166
Understanding nitrous oxide (N2O) fluxes from grain–legume crops in semiarid and arid regions is necessary if we are to improve our knowledge of global terrestrial N2O losses resulting from biological N2 fixation. N2O fluxes were measured from a rain‐fed soil, cropped to a grain–legume in a semiarid region of southwestern Australia for 1 year on a subdaily basis. The site included plots planted to narrow‐leafed lupin (Lupinus angustifolius; ‘lupin’) and plots left bare (no lupin). Fluxes were measured using soil chambers connected to a fully automated system that measured N2O by gas chromatography. Daily N2O fluxes were low (?0.5 to 24 g N2O‐N ha?1 day?1) and not different between treatments, culminating in an annual loss of 127 g N2O‐N ha?1. Greatest daily N2O fluxes occurred from both treatments in the postharvest period, and following a series of summer and autumn rainfall events. At this time of the year, soil conditions were conducive to soil microbial N2O production: elevated soil water contents, increased inorganic nitrogen (N) and dissolved organic carbon concentrations, and soil temperatures generally > 25 °C; furthermore, there was no active plant growth to compete for mineralized N. N2O emissions from the decomposition of legume crop residue were low, and approximately half that predicted using the currently recommended IPCC methodology. Furthermore, the contribution of the biological N2 fixation process to N2O emissions appeared negligible in the present study, supporting its omission as a source of N2O from the IPCC methodology for preparing national greenhouse gas inventories. 相似文献
13.
Bärbel Tiemeyer Elisa Albiac Borraz Jürgen Augustin Michel Bechtold Sascha Beetz Colja Beyer Matthias Drösler Martin Ebli Tim Eickenscheidt Sabine Fiedler Christoph Förster Annette Freibauer Michael Giebels Stephan Glatzel Jan Heinichen Mathias Hoffmann Heinrich Höper Gerald Jurasinski Katharina Leiber‐Sauheitl Mandy Peichl‐Brak Niko Roßkopf Michael Sommer Jutta Zeitz 《Global Change Biology》2016,22(12):4134-4149
Drainage has turned peatlands from a carbon sink into one of the world's largest greenhouse gas (GHG) sources from cultivated soils. We analyzed a unique data set (12 peatlands, 48 sites and 122 annual budgets) of mainly unpublished GHG emissions from grasslands on bog and fen peat as well as other soils rich in soil organic carbon (SOC) in Germany. Emissions and environmental variables were measured with identical methods. Site‐averaged GHG budgets were surprisingly variable (29.2 ± 17.4 t CO2‐eq. ha?1 yr?1) and partially higher than all published data and the IPCC default emission factors for GHG inventories. Generally, CO2 (27.7 ± 17.3 t CO2 ha?1 yr?1) dominated the GHG budget. Nitrous oxide (2.3 ± 2.4 kg N2O‐N ha?1 yr?1) and methane emissions (30.8 ± 69.8 kg CH4‐C ha?1 yr?1) were lower than expected except for CH4 emissions from nutrient‐poor acidic sites. At single peatlands, CO2 emissions clearly increased with deeper mean water table depth (WTD), but there was no general dependency of CO2 on WTD for the complete data set. Thus, regionalization of CO2 emissions by WTD only will remain uncertain. WTD dynamics explained some of the differences between peatlands as sites which became very dry during summer showed lower emissions. We introduced the aerated nitrogen stock (Nair) as a variable combining soil nitrogen stocks with WTD. CO2 increased with Nair across peatlands. Soils with comparatively low SOC concentrations showed as high CO2 emissions as true peat soils because Nair was similar. N2O emissions were controlled by the WTD dynamics and the nitrogen content of the topsoil. CH4 emissions can be well described by WTD and ponding duration during summer. Our results can help both to improve GHG emission reporting and to prioritize and plan emission reduction measures for peat and similar soils at different scales. 相似文献
14.
Micrometeorological measurements over 3 years reveal differences in N2O emissions between annual and perennial crops 下载免费PDF全文
Diego Abalos Shannon E. Brown Andrew C. Vanderzaag Robert J. Gordon Kari E. Dunfield Claudia Wagner‐Riddle 《Global Change Biology》2016,22(3):1244-1255
Perennial crops can deliver a wide range of ecosystem services compared to annual crops. Some of these benefits are achieved by lengthening the growing season, which increases the period of crop water and nutrient uptake, pointing to a potential role for perennial systems to mitigate soil nitrous oxide (N2O) emissions. Employing a micrometeorological method, we tested this hypothesis in a 3‐year field experiment with a perennial grass‐legume mixture and an annual corn monoculture. Given that N2O emissions are strongly dependent on the method of fertilizer application, two manure application options commonly used by farmers for each crop were studied: injection vs. broadcast application for the perennial; fall vs. spring application for the annual. Across the 3 years, lower N2O emissions (P < 0.001) were measured for the perennial compared to the annual crop, even though annual N2O emissions increased tenfold for the perennial after ploughing. The percentage of N2O lost per unit of fertilizer applied was 3.7, 3.1 and 1.3 times higher for the annual for each consecutive year. Differences in soil organic matter due to the contrasting root systems of these crops are probably a major factor behind the N2O reduction. We found that a specific manure management practice can lead to increases or reductions in annual N2O emissions depending on environmental variables. The number of freeze‐thaw cycles during winter and the amount of rainfall after fertilization in spring were key factors. Therefore, general manure management recommendations should be avoided because interannual weather variability has the potential to determine if a specific practice is beneficial or detrimental. The lower N2O emissions of perennial crops deserve further research attention and must be considered in future land‐use decisions. Increasing the proportion of perennial crops in agricultural landscapes may provide an overlooked opportunity to regulate N2O emissions. 相似文献
15.
We used a climate‐driven regression model to develop spatially resolved estimates of soil‐CO2 emissions from the terrestrial land surface for each month from January 1980 to December 1994, to evaluate the effects of interannual variations in climate on global soil‐to‐atmosphere CO2 fluxes. The mean annual global soil‐CO2 flux over this 15‐y period was estimated to be 80.4 (range 79.3–81.8) Pg C. Monthly variations in global soil‐CO2 emissions followed closely the mean temperature cycle of the Northern Hemisphere. Globally, soil‐CO2 emissions reached their minima in February and peaked in July and August. Tropical and subtropical evergreen broad‐leaved forests contributed more soil‐derived CO2 to the atmosphere than did any other vegetation type (~30% of the total) and exhibited a biannual cycle in their emissions. Soil‐CO2 emissions in other biomes exhibited a single annual cycle that paralleled the seasonal temperature cycle. Interannual variability in estimated global soil‐CO2 production is substantially less than is variability in net carbon uptake by plants (i.e., net primary productivity). Thus, soils appear to buffer atmospheric CO2 concentrations against far more dramatic seasonal and interannual differences in plant growth. Within seasonally dry biomes (savannas, bushlands and deserts), interannual variability in soil‐CO2 emissions correlated significantly with interannual differences in precipitation. At the global scale, however, annual soil‐CO2 fluxes correlated with mean annual temperature, with a slope of 3.3 Pg C y?1 per °C. Although the distribution of precipitation influences seasonal and spatial patterns of soil‐CO2 emissions, global warming is likely to stimulate CO2 emissions from soils. 相似文献
16.
Estimation of nitrous oxide, nitric oxide and ammonia emissions from croplands in East, Southeast and South Asia 总被引:23,自引:0,他引:23
Agricultural activities have greatly altered the global nitrogen (N) cycle and produced nitrogenous gases of environmental significance. More than half of all chemical N fertilizer produced globally is used in crop production in East, Southeast and South Asia, where rice is central to nutrition. Emissions of nitrous oxide (N2O), nitric oxide (NO) and ammonia (NH3) from croplands in this region were estimated by considering background emission and emissions resulting from N added to croplands, including chemical N, animal manure, biologically fixed N and N in crop residues returned to fields. Background emission fluxes of N2O and NO from croplands were estimated to be 1.22 and 0.57 kg N ha?1 yr?1, respectively. Separate fertilizer‐induced emission factors were estimated for upland fields and rice fields. Total N2O emission from croplands in the study region was estimated to be 1.19 Tg N yr?1, with 43% contributed by background emissions. The average fertilizer‐induced N2O emission, however, accounts for only 0.93% of the applied N, which is less than the default IPCC value of 1.25%, because of the low emission factor from paddy fields. Total NO emission was 591 Gg N yr?1 in the study region, with 40% from background emissions. The average fertilizer‐induced NO emission factor was 0.48%. Total NH3 emission was estimated to be 11.8 Tg N yr?1. The use of urea and ammonium bicarbonate and the cultivation of rice led to a high average NH3 loss rate from chemical N fertilizer in the study region. Emissions were displayed at a 0.5° × 0.5° resolution with the use of a global landuse database. 相似文献
17.
Effects of Climate Change Drivers on Nitrous Oxide Fluxes in an Upland Temperate Grassland 总被引:1,自引:0,他引:1
Amélie A. M. Cantarel Juliette M. G. Bloor Nicolas Deltroy Jean-François Soussana 《Ecosystems》2011,14(2):223-233
Despite increasing interest in the patterns of trace gas emissions in terrestrial ecosystems, little is known about the impacts
of climate change on nitrous oxide (N2O) fluxes. The aim of this study was to determine the importance of the three main drivers of climate change (warming, summer
drought, and elevated CO2 concentrations) on N2O fluxes from an extensively managed, upland grassland. Over a 2-year period, we monitored N2O fluxes in an in situ ecosystem manipulation experiment simulating the climate predicted for the study area in 2080 (3.5°C
temperature increase, 20% reduction in summer rainfall and atmospheric CO2 levels of 600 ppm). N2O fluxes showed significant seasonal and interannual variation irrespective of climate treatment, and were higher in summer
and autumn compared with winter and spring. Overall, N2O emissions showed a positive correlation with soil temperature and rainfall. Elevated temperature had a positive impact on
mean annual N2O fluxes but effects were only significant in 2007. Contrary to expectations, neither combined summer drought and warming
nor the simultaneous application of elevated atmospheric CO2 concentrations, summer drought and warming had any significant effect on annual N2O fluxes. However, the maximum N2O flux rates observed during the study occurred when elevated CO2 was combined with warming and drought, suggesting the potential for important, short-term N2O–N losses in enriched CO2 environments. Taken together, our results suggest that the N2O responses of temperate, extensively managed grasslands to future climate change scenarios may be primarily driven by temperature
effects. 相似文献
18.
Estimating the impact of changing fertilizer application rate, land use, and climate on nitrous oxide emissions in Irish grasslands 总被引:1,自引:0,他引:1
Dong-Gill Kim Rashad Rafique Paul Leahy Mark Cochrane Gerard Kiely 《Plant and Soil》2014,374(1-2):55-71
Aim
This study examines the impact of changing nitrogen (N) fertilizer application rates, land use and climate on N fertilizer-derived direct nitrous oxide (N2O) emissions in Irish grasslands.Methods
A set of N fertilizer application rates, land use and climate change scenarios were developed for the baseline year 2000 and then for the years 2020 and 2050. Direct N2O emissions under the different scenarios were estimated using three different types of emission factors and a newly developed Irish grassland N2O emissions empirical model.Results
There were large differences in the predicted N2O emissions between the methodologies, however, all methods predicted that the overall N2O emissions from Irish grasslands would decrease by 2050 (by 40–60 %) relative to the year 2000. Reduced N fertilizer application rate and land-use changes resulted in decreases of 19–34 % and 11–60 % in N2O emission respectively, while climate change led to an increase of 5–80 % in N2O emission by 2050.Conclusions
It was observed in the study that a reduction in N fertilizer and a reduction in the land used for agriculture could mitigate emissions of N2O, however, future changes in climate may be responsible for increases in emissions causing the positive feedback of climate on emissions of N2O. 相似文献19.
TIM J. CLOUGH LAURA E. BUCKTHOUGHT FRANCIS M. KELLIHER† ROBERT R. SHERLOCK 《Global Change Biology》2007,13(5):1016-1027
There is uncertainty in the estimates of indirect nitrous oxide (N2O) emissions as defined by the Intergovernmental Panel on Climate Change (IPCC). The uncertainty is due to the challenge and dearth of in situ measurements. Recent work in a subtropical stream system has shown the potential for diurnal variability to influence the downstream N transfer, N form, and estimates of in‐stream N2O production. Studies in temperate stream systems have also shown diurnal changes in stream chemistry. The objectives of this study were to measure N2O fluxes and dissolved N2O concentrations from a spring‐fed temperate river to determine if diurnal cycles were occurring. The study was performed during a 72 h period, over a 180 m reach, using headspace chamber methodology. Significant diurnal cycles were observed in radiation, river temperature and chemistry including dissolved N2O‐N concentrations. These data were used to further assess the IPCC methodology and experimental methodology used. River NO3‐N and N2O‐N concentrations averaged 3.0 mg L−1 and 1.6 μg L−1, respectively, with N2O saturation reaching a maximum of 664%. The N2O‐N fluxes, measured using chamber methodology, ranged from 52 to 140 μg m−2 h−1 while fluxes predicted using the dissolved N2O concentration ranged from 13 to 25 μg m−2 h−1. The headspace chamber methodology may have enhanced the measured N2O flux and this is discussed. Diurnal cycles in N2O% saturation were not large enough to influence downstream N transfer or N form with variability in measured N2O fluxes greater and more significant than diurnal variability in N2O% saturation. The measured N2O fluxes, extrapolated over the study reach area, represented only 6 × 10−4% of the NO3‐N that passed through the study reach over a 72 h period. This is only 0.1% of the IPCC calculated flux. 相似文献
20.
Thomas Nemecek Julian Schnetzer Jürgen Reinhard 《The International Journal of Life Cycle Assessment》2016,21(9):1361-1378