scholarly journals Spatial and temporal patterns of CH<sub>4</sub> and N<sub>2</sub>O fluxes in terrestrial ecosystems of North America during 1979–2008: application of a global biogeochemistry model

2010 ◽  
Vol 7 (9) ◽  
pp. 2673-2694 ◽  
Author(s):  
H. Tian ◽  
X. Xu ◽  
M. Liu ◽  
W. Ren ◽  
C. Zhang ◽  
...  
Keyword(s):  
North America ◽  
Terrestrial Ecosystem ◽  
Terrestrial Ecosystems ◽  
N2o Emission ◽  
Annual Precipitation ◽  
Continental Scale ◽  
The Past ◽  
The Us ◽  
N2o Fluxes ◽  
Ch4 And N2o

Abstract. Continental-scale estimations of terrestrial methane (CH4) and nitrous oxide (N2O) fluxes over a long time period are crucial to accurately assess the global balance of greenhouse gases and enhance our understanding and prediction of global climate change and terrestrial ecosystem feedbacks. Using a process-based global biogeochemical model, the Dynamic Land Ecosystem Model (DLEM), we quantified simultaneously CH4 and N2O fluxes in North America's terrestrial ecosystems from 1979 to 2008. During the past 30 years, approximately 14.69 ± 1.64 T g C a−1 (1 T g = 1012 g) of CH4, and 1.94 ± 0.1 T g N a−1 of N2O were released from terrestrial ecosystems in North America. At the country level, both the US and Canada acted as CH4 sources to the atmosphere, but Mexico mainly oxidized and consumed CH4 from the atmosphere. Wetlands in North America contributed predominantly to the regional CH4 source, while all other ecosystems acted as sinks for atmospheric CH4, of which forests accounted for 36.8%. Regarding N2O emission in North America, the US, Canada, and Mexico contributed 56.19%, 18.23%, and 25.58%, respectively, to the continental source over the past 30 years. Forests and croplands were the two ecosystems that contributed most to continental N2O emission. The inter-annual variations of CH4 and N2O fluxes in North America were mainly attributed to year-to-year climatic variability. While only annual precipitation was found to have a significant effect on annual CH4 flux, both mean annual temperature and annual precipitation were significantly correlated to annual N2O flux. The regional estimates and spatiotemporal patterns of terrestrial ecosystem CH4 and N2O fluxes in North America generated in this study provide useful information for global change research and policy making.

scholarly journals Spatial and temporal patterns of CH<sub>4</sub> and N<sub>2</sub>O fluxes in terrestrial ecosystems of North America during 1979–2008: application of a global biogeochemistry model

2010 ◽  
Vol 7 (2) ◽  
pp. 2831-2887
Author(s):  
H. Tian ◽  
X. Xu ◽  
M. Liu ◽  
W. Ren ◽  
C. Zhang ◽  
...  
Keyword(s):  
United States ◽  
North America ◽  
Terrestrial Ecosystem ◽  
Terrestrial Ecosystems ◽  
The United States ◽  
N2o Emission ◽  
Annual Precipitation ◽  
The Past ◽  
N2o Fluxes ◽  
Ch4 And N2o

Abstract. Continental-scale estimations of terrestrial methane (CH4) and nitrous oxide (N2O) fluxes over a long time period are crucial to accurately assess the global balance of greenhouse gases and enhance our understanding and prediction of global climate change and terrestrial ecosystem feedbacks. Using a process-based global biogeochemical model, the Dynamic Land Ecosystem Model (DLEM), we quantified simultaneously CH4 and N2O fluxes in North America's terrestrial ecosystems from 1979 to 2008. During the past 30 years, approximately 14.69±1.64 T g C a−1 (1 T g=1012 g) of CH4, and 1.94±0.16 T g N a−1 of N2O were released from terrestrial ecosystems in North America. At the country level, both the United States and Canada acted as CH4 sources to the atmosphere, but Mexico mainly oxidized and consumed CH4 from the atmosphere. Wetlands in North America contributed predominantly to the regional CH4 source, while all other ecosystems acted as sinks for atmospheric CH4, of which forests accounted for 36.8%. Regarding N2O emission in North America, the United States, Canada, and Mexico contributed 56.19%, 18.23%, and 25.58%, respectively, to the continental source over the past 30 years. Forests and croplands were the two ecosystems that contributed most to continental N2O emission. The inter-annual variations of CH4 and N2O fluxes in North America were mainly attributed to year-to-year climatic variability. While only annual precipitation was found to have a significant effect on annual CH4 flux, both mean annual temperature and annual precipitation were significantly correlated to annual N2O flux. The regional estimates and spatiotemporal patterns of terrestrial ecosystem CH4 and N2O fluxes in North America generated in this study provide useful information for global change research and policy making.

scholarly journals CH<sub>4</sub> and N<sub>2</sub>O dynamics in the boreal forest–mire ecotone

2015 ◽  
Vol 12 (2) ◽  
pp. 281-297 ◽  
Author(s):  
B. Tupek ◽  
K. Minkkinen ◽  
J. Pumpanen ◽  
T. Vesala ◽  
E. Nikinmaa
Keyword(s):  
Ground Water ◽  
N2o Emission ◽  
N2o Emissions ◽  
Summer Drought ◽  
Drought Period ◽  
Local Climate ◽  
N2o Fluxes ◽  
Ch4 And N2o ◽  
Water Saturated ◽  
Boreal Landscapes

Abstract. In spite of advances in greenhouse gas research, the spatiotemporal CH4 and N2O dynamics of boreal landscapes remain challenging, e.g., we need clarification of whether forest–mire transitions are occasional hotspots of landscape CH4 and N2O emissions during exceptionally high and low ground water level events. In our study, we tested the differences and drivers of CH4 and N2O dynamics of forest/mire types in field conditions along the soil moisture gradient of the forest–mire ecotone. Soils changed from Podzols to Histosols and ground water rose downslope from a depth of 10 m in upland sites to 0.1 m in mires. Yearly meteorological conditions changed from being exceptionally wet to typical and exceptionally dry for the local climate. The median fluxes measured with a static chamber technique varied from −51 to 586 μg m−2 h−1 for CH4 and from 0 to 6 μg m−2 h−1 for N2O between forest and mire types throughout the entire wet–dry period. In spite of the highly dynamic soil water fluctuations in carbon rich soils in forest–mire transitions, there were no large peak emissions in CH4 and N2O fluxes and the flux rates changed minimally between years. Methane uptake was significantly lower in poorly drained transitions than in the well-drained uplands. Water-saturated mires showed large CH4 emissions, which were reduced entirely during the exceptional summer drought period. Near-zero N2O fluxes did not differ significantly between the forest and mire types probably due to their low nitrification potential. When upscaling boreal landscapes, pristine forest–mire transitions should be regarded as CH4 sinks and minor N2O sources instead of CH4 and N2O emission hotspots.

Tree death as a crucial geomorphic agent in temperate forests: effects of weak and severe disturbances from local to continental scale

2020 ◽  
Author(s):  
Pavel Šamonil ◽  
Pavel Daněk ◽  
James A. Lutz ◽  
Jakub Jaroš ◽  
Anna Rousová ◽  
...  
Keyword(s):  
Terrestrial Ecosystem ◽  
Terrestrial Ecosystems ◽  
Ecosystem Dynamics ◽  
Retention Capacity ◽  
Tree Species Composition ◽  
Continental Scale ◽  
Standing Trees ◽  
Forested Landscapes ◽  
Tree Uprooting ◽  
Hillslope Processes

&lt;p&gt;Hillslope processes in terrestrial ecosystems are significantly modified by changes in climate and land use. At the same time they strongly influence ecosystem retention capacity, pedocomplexity and biodiversity. This undoubtedly makes hillslope processes one of the crucial components of terrestrial ecosystem dynamics. In this study we focus on the long overlooked biogeomorphological impact of tree death in forested landscapes. Tree uprooting caused by strong storms affects soil and regolith formation and movement quite differently from the decomposition of intact root systems of standing trees that died due to e.g. fire or bark beetle infestation. We quantify the biogeomorphic processes associated with tree death in various terrestrial forest ecosystems and specifically assess (i) the significance of these processes in hillslope dynamics (e.g. slope denudation) of forested landscapes and (ii) the extent to which infrequent severe disturbances can shape these dynamics.&lt;/p&gt;&lt;p&gt;We used data from repeated tree censuses carried out in ten permanent forest plots (13&amp;#8211;74 ha in area) located in Central Europe and North America, differing in a range of characteristics such as tree species composition, climate and disturbance regime. In total, life history of more than 134,000 trees was recorded over periods of up to 47 years, during which about one third of these trees died. Using this information together with empirical models and allometric equations we were able to quantify the average areas and volumes of soil annually affected by dying trees. These quantities differed markedly between sites with different disturbance regimes. Tree uprooting-related volumes accounted annually for 0.01&amp;#8211;13.5 m&lt;sup&gt;3&lt;/sup&gt;ha&lt;sup&gt;&amp;#8722;1&lt;/sup&gt; reaching maximum values on sites with occurrence of infrequent strong windstorms (Zofin and Boubin primeval forests, Czech Republic). Volumes related to trees that died standing ranged anually between 0.17 and 20.7 m&lt;sup&gt;3&lt;/sup&gt;ha&lt;sup&gt;&amp;#8722;1&lt;/sup&gt; and were highest in the presence of stand-replacing fires (Yosemite National Park, U.S.). Comparison of these quantities with long-term erosion rates derived using cosmogenic nuclides (&lt;sup&gt;10&lt;/sup&gt;Be) suggests that on certain sites, over the last few millennia, tree uprooting can be the main driver of soil erosion.&lt;/p&gt;

scholarly journals Carbon balance of South Asia constrained by passenger aircraft CO<sub>2</sub> measurements

2011 ◽  
Vol 11 (9) ◽  
pp. 4163-4175 ◽  
Author(s):  
P. K. Patra ◽  
Y. Niwa ◽  
T. J. Schuck ◽  
C. A. M. Brenninkmeijer ◽  
T. Machida ◽  
...  
Keyword(s):  
South Asia ◽  
Transport Model ◽  
Terrestrial Ecosystem ◽  
Terrestrial Ecosystems ◽  
Ecosystem Model ◽  
Terrestrial Ecosystem Model ◽  
Terra Incognita ◽  
Ch4 And N2o ◽  
Carbon Dioxide Co2 ◽  
Passenger Aircraft

Abstract. Quantifying the fluxes of carbon dioxide (CO2) between the atmosphere and terrestrial ecosystems in all their diversity, across the continents, is important and urgent for implementing effective mitigating policies. Whereas much is known for Europe and North America for instance, in comparison, South Asia, with 1.6 billion inhabitants and considerable CO2 fluxes, remained terra incognita in this respect. We use regional measurements of atmospheric CO2 aboard a Lufthansa passenger aircraft between Frankfurt (Germany) and Chennai (India) at cruise altitude, in addition to the existing network sites for 2008, to estimate monthly fluxes for 64-regions using Bayesian inversion and transport model simulations. The applicability of the model's transport parameterization is confirmed using SF6, CH4 and N2O simulations for the CARIBIC datasets. The annual amplitude of carbon flux obtained by including the aircraft data is twice as large as the fluxes simulated by a terrestrial ecosystem model that was applied to prescribe the fluxes used in the inversions. It is shown that South Asia sequestered carbon at a rate of 0.37 ± 0.20 Pg C yr−1 (1 Pg C = 1015 g of carbon in CO2) for the years 2007 and 2008. The seasonality and the strength of the calculated monthly fluxes are successfully validated using independent measurements of vertical CO2 profiles over Delhi and spatial variations at cruising altitude over Asia aboard Japan Airlines passenger aircraft.

scholarly journals Probing the past 30 year phenology trend of US deciduous forests

2015 ◽  
Vol 12 (8) ◽  
pp. 6037-6080 ◽  
Author(s):  
X. Yue ◽  
N. Unger ◽  
T. F. Keenan ◽  
X. Zhang ◽  
C. S. Vogel
Keyword(s):  
New England ◽  
Model Performance ◽  
Remote Sensing Data ◽  
Deciduous Forests ◽  
Significant Advance ◽  
Spring Phenology ◽  
Continental Scale ◽  
The Past ◽  
The Us

Abstract. Phenology is experiencing dramatic changes over deciduous forests in the US. Estimates of trends in phenology on the continental scale are uncertain, however, with studies failing to agree on both the magnitude and spatial distribution of trends in spring and autumn. This is due to the sparsity of in situ records, uncertainties associated with remote sensing data, and the regional focus of many studies. It has been suggested that reported trends are a result of recent temperature changes, though multiple processes are thought to be involved and the nature of the temperature forcing remains unknown. To date, no study has directly attributed long-term phenological trends to individual forcings across the US through integrating observations with models. Here, we construct an extensive database of ground measurements of phenological events across the US, and use it to calibrate and evaluate a suite of phenology models. The models use variations of the accumulative temperature summation, with additional chilling requirements for spring phenology and photoperiod limitation for autumn. Including a chilling requirement or photoperiod limitation does not improve model performance, suggesting that temperature change, especially in spring and autumn, is the dominant driver of the observed trend during the past 3 decades. Our results show that phenological trends are not uniform over the contiguous US, with a significant advance of 0.34 day yr−1 for the spring budburst in the East, a delay of 0.15 day yr−1 for the autumn dormancy onset in the Northeast and West, but no evidence of change elsewhere. Relative to the 1980s, the growing season in the 2000s is extended by about 1 week (3–4%) in the East, New England, and the upper Rocky Mountains forests. These results help reconcile conflicting reports of phenological trends in the literature, and directly attribute observed trends to long-term changes in temperature.

scholarly journals CH<sub>4</sub> and N<sub>2</sub>O dynamics in the boreal forest–mire ecotone

2014 ◽  
Vol 11 (6) ◽  
pp. 8049-8084 ◽  
Author(s):  
B. Tupek ◽  
K. Minkkinen ◽  
J. Pumpanen ◽  
T. Vesala ◽  
E. Nikinmaa
Keyword(s):  
Ground Water ◽  
N2o Emission ◽  
N2o Emissions ◽  
Summer Drought ◽  
Drought Period ◽  
Local Climate ◽  
N2o Fluxes ◽  
Spatio Temporal ◽  
Ch4 And N2o ◽  
Water Saturated

Abstract. In spite of advances in greenhouse gas research, the spatio-temporal CH4 and N2O dynamics of boreal landscape remain challenging, e.g. we need clarification of whether the forest–mire transitions are occasional hotspots of landscape CH4 and N2O emissions during exceptionally high and low ground water level events. In our study, we tested the differences and drivers of CH4 and N2O dynamics of forest/mire types in field conditions along the soil moisture gradient of the forest–mire ecotone. Soils changed from podzols to histosols and ground water rose downslope from the depth of 10 m in upland sites to 0.1 m in mires. Yearly meteorological conditions changed from being exceptionally wet to typical and exceptionally dry for the local climate. The median fluxes measured with a static chamber technique varied from −51 to 586 μg m−2 h−1 for CH4 and from 0 to 6 μg m−2 h−1 for N2O between forest/mire types throughout the entire wet-dry period. In spite of the highly dynamic soil water fluctuations in carbon rich soils in forest–mire transitions, there were no large peak emissions in CH4 and N2O fluxes and the flux rates changed minimally between years. Methane oxidations were significantly lower in poorly drained transitions than in the well-drained uplands. Water saturated mires showed large CH4 emissions, which were reduced entirely during the exceptional summer drought period. Near zero N2O fluxes did not differ significantly between the forest/mire types probably due to their low nitrification potential. When up scaling boreal landscapes, pristine forest–mire transitions should be categorized as CH4 oxidation types and background N2O emission types instead of CH4 and N2O emission hotspots.

Advances In Asthma Care

2003 ◽  
Vol 1 (1) ◽  
pp. 87-90 ◽  
Author(s):  
Chris Garvey
Keyword(s):  
Healthcare Costs ◽  
Professional Organizations ◽  
Current Status ◽  
Asthma Care ◽  
Advanced Level ◽  
Clinical Criteria ◽  
Asthma Knowledge ◽  
The Past ◽  
The Us ◽  
Examination Process

Asthma rates in the US have risen during the past 25 years, as have asthma-related morbidity and healthcare costs. Professional organizations involved in asthma care have identified the need to assure that an advanced level of asthma knowledge and skill is available to patients with asthma, their families, and insurers. This need led to development of the certification for asthma educators. The Certified Asthma Educator (AE-C) must meet specific clinical criteria and pass a standardized examination designed to evaluate knowledge and skill for providing competent asthma education and coordination. The development and current status of the Certified Asthma Educator examination process and content are discussed, as are goals of the certification

BP Global Energy Outlook 2030

2013 ◽  
pp. 109-128 ◽  
Author(s):  
C. Rühl
Keyword(s):  
Emerging Economies ◽  
Energy Demand ◽  
Fossil Fuels ◽  
Net Energy ◽  
Global Energy ◽  
The Past ◽  
Market Shares ◽  
The Us ◽  
Almost All ◽  
Oil Gas

This paper presents the highlights of the third annual edition of the BP Energy Outlook, which sets out BP’s view of the most likely developments in global energy markets to 2030, based on up-to-date analysis and taking into account developments of the past year. The Outlook’s overall expectation for growth in global energy demand is to be 36% higher in 2030 than in 2011 and almost all the growth coming from emerging economies. It also reflects shifting expectations of the pattern of supply, with unconventional sources — shale gas and tight oil together with heavy oil and biofuels — playing an increasingly important role and, in particular, transforming the energy balance of the US. While the fuel mix is evolving, fossil fuels will continue to be dominant. Oil, gas and coal are expected to converge on market shares of around 26—28% each by 2030, and non-fossil fuels — nuclear, hydro and renewables — on a share of around 6—7% each. By 2030, increasing production and moderating demand will result in the US being 99% self-sufficient in net energy. Meanwhile, with continuing steep economic growth, major emerging economies such as China and India will become increasingly reliant on energy imports. These shifts will have major impacts on trade balances.

World Economy: Prospects and Barriers for Recovery

2012 ◽  
pp. 61-83 ◽  
Author(s):  
M. Ershov
Keyword(s):  
World Economy ◽  
Western World ◽  
Short Time Period ◽  
Market Segments ◽  
Junk Bonds ◽  
The Past ◽  
Time Period ◽  
The Us ◽  
Global Liquidity ◽  
Short Time

According to the latest forecasts, it will take 10 years for the world economy to get back to “decent shape”. Some more critical estimates suggest that the whole western world will have a “colossal mess” within the next 5–10 years. Regulators of some major countries significantly and over a short time‑period changed their forecasts for the worse which means that uncertainty in the outlook for the future persists. Indeed, the intensive anti‑crisis measures have reduced the severity of the past problems, however the problems themselves have not disappeared. Moreover, some of them have become more intense — the eurocrisis, excessive debts, global liquidity glut against the backdrop of its deficit in some of market segments. As was the case prior to the crisis, derivatives and high‑risk operations with “junk” bonds grow; budget problems — “fiscal cliff” in the US — and other problems worsen. All of the above forces the regulators to take unprecedented (in their scope and nature) steps. Will they be able to tackle the problems which emerge?

Holism, Chinese Medicine and Systems Ideologies: Rewriting the Past to Imagine the Future

2018 ◽  
Author(s):  
Volker Scheid
Keyword(s):  
Eighteenth Century ◽  
Chinese Medicine ◽  
Medical Humanities ◽  
Science And Technology Studies ◽  
Human Beings ◽  
The Past ◽  
Starting Point ◽  
The Us ◽  
Shared Objective ◽  
Definition Of

This chapter explores the articulations that have emerged over the last half century between various types of holism, Chinese medicine and systems biology. Given the discipline’s historical attachments to a definition of ‘medicine’ that rather narrowly refers to biomedicine as developed in Europe and the US from the eighteenth century onwards, the medical humanities are not the most obvious starting point for such an inquiry. At the same time, they do offer one advantage over neighbouring disciplines like medical history, anthropology or science and technology studies for someone like myself, a clinician as well as a historian and anthropologist: their strong commitment to the objective of facilitating better medical practice. This promise furthermore links to the wider project of critique, which, in Max Horkheimer’s definition of the term, aims at change and emancipation in order ‘to liberate human beings from the circumstances that enslave them’. If we take the critical medical humanities as explicitly affirming this shared objective and responsibility, extending the discipline’s traditional gaze is not a burden but becomes, in fact, an obligation.

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