Water-use efficiency and transpiration across European forests during the Anthropocene

The Earth’s carbon and hydrologic cycles are intimately coupled by gas exchange through plant stomata1, 2, 3. However, uncertainties in the magnitude4, 5, 6 and consequences7, 8 of the physiological responses9, 10 of plants to elevated CO2 in natural environments hinders modelling of terrestrial water cycling and carbon storage11. Here we use annually resolved long-term δ13C tree-ring measurements across a European forest network to reconstruct the physiologically driven response of intercellular CO2 (Ci) caused by atmospheric CO2 (Ca) trends. When removing meteorological signals from the δ13C measurements, we find that trees across Europe regulated gas exchange so that for one ppmv atmospheric CO2 increase, Ci increased by ~0.76 ppmv, most consistent with moderate control towards a constant Ci/Ca ratio. This response corresponds to twentieth-century intrinsic water-use efficiency (iWUE) increases of 14 ± 10 and 22 ± 6% at broadleaf and coniferous sites, respectively. An ensemble of process-based global vegetation models shows similar CO2 effects on iWUE trends. Yet, when operating these models with climate drivers reintroduced, despite decreased stomatal opening, 5% increases in European forest transpiration are calculated over the twentieth century. This counterintuitive result arises from lengthened growing seasons, enhanced evaporative demand in a warming climate, and increased leaf area, which together oppose effects of CO2-induced stomatal closure. Our study questions changes to the hydrological cycle, such as reductions in transpiration and air humidity, hypothesized to result from plant responses to anthropogenic emissions.

Innovative Agricultural Approaches of Promoting Food Security in Eritrea: Trends, Challenges and Opportunities for Growth: Proceedings of the Workshop of the Association of Eritreans in Agricultural Sciences (AEAS)

Eritrea is a Sahel country in terms of climate, and rainfall is low and highly variable. Shortage of food is thus a recurrent problem, and food security one of the key issues in development. The present publication presents the results of a nationwide workshop organised in 2006 in Asmara, Eritrea, by the Association of Eritreans in Agricultural Sciences (AEAS). The workshop was attended by over 200 participants from government administration, academia, development circles including NGOs and UN organisations. Specifically, the present publication deals with themes such as biotechnology, non-wood forest products, spate irrigation, the role of women relating to food security, and institutional and organisational aspects of food security. It also contains a chapter with policy recommendations, as well as an extensive summary of the main findings (paper abstracts) in Tigrinya.

Source apportionment of elemental carbon in Beijing, China: insights from radiocarbon and organic marker measurements

Elemental carbon (EC) or black carbon (BC) in the atmosphere has a strong influence on both climate and human health. In this study, radiocarbon (14C) based source apportionment is used to distinguish between fossil fuel and biomass burning sources of EC isolated from aerosol filter samples collected in Beijing from June 2010 to May 2011. The 14C results demonstrate that EC is consistently dominated by fossil-fuel combustion throughout the whole year with a mean contribution of 79% ± 6% (ranging from 70% to 91%), though EC has a higher mean and peak concentrations in the cold season. The seasonal molecular pattern of hopanes (i.e., a class of organic markers mainly emitted during the combustion of different fossil fuels) indicates that traffic-related emissions are the most important fossil source in the warm period and coal combustion emissions are significantly increased in the cold season. By combining 14C based source apportionment results and picene (i.e., an organic marker for coal emissions) concentrations, relative contributions from coal (mainly from residential bituminous coal) and vehicle to EC in the cold period were estimated as 25 ± 4% and 50 ± 7%, respectively, whereas the coal combustion contribution was negligible or very small in the warm period.

Irrigation development in Eritrea: potentials and constraints: Proceedings of the workshop of AEAS and SLM Programme Eritrea

Development of irrigation, which is of crucial importance in Eritrea, is perceived by many as the main technique for improving the precarious food security situation in this Sahelian country in the Horn of Africa. The present publication presents the outcome of a nationwide workshop held in 2003, which brought together administrators, scientists, and members of public development agencies and NGOs. These workshop participants presented experiences, lessons learnt, and ideas about how to move forward in relation to development of irrigation in Eritrea. Specifically, the publication deals with the following broad themes, lessons learnt, and experiences in Eritrea: · spate irrigation systems and measurement of performance, as well as experience with modernisation of spate irrigation systems in Eritrea · small-scale irrigation systems and their potentials and pitfalls, including development of low-cost micro irrigation · climate and irrigation, including rainfall forecasts · socio-economic aspects of irrigation, including gender questions, institutional requirements, and irrigation and livelihoods The publication contains an extensive summary in the Tigrinya language, in order to facilitate access to the key findings by local non-English-speaking stakeholders in irrigation development.

Human and climatic impact on mires: a case study of Les Amburnex mire, Swiss Jura Mountains

Modern period long-term human and climatic impacts on a small mire in the Jura Mountains were assessed using testate amoebae, macrofossils and pollen. This multiproxy data analysis permitted detailed interpretations of local and regional environmental change and thus a partial disentanglement of the different variables that influence long-term mire development. From the Middle Ages until a.d. 1700 the mire vegetation was characterised by ferns, Caltha and Vaccinium, but then abruptly changed into the modern vegetation characterised by Cyperaceae, Potentilla and Sphagnum. The cause for this change was most probably deforestation, possibly enhanced by climatic cooling. A decrease in trampling intensity by domestic animals from a.d. 1950 onwards allowed Sphagnum growth and climatic warming in the a.d. 1980s and 1990s may have been responsible for considerable changes in the species composition. The mire investigated is an example of the rapid changes in mire vegetation and peat development that occurred throughout the central European mountain region during the past centuries as a result of changing climate and land-use practice. These processes are still active today and will determine the future development of high-altitude mires.

Holocene biomass burning and global dynamics of the carbon cycle

Fire regimes have changed during the Holocene due to changes in climate, vegetation, and in human practices. Here, we hypothesise that changes in fire regime may have affected the global CO2 concentration in the atmosphere through the Holocene. Our data are based on quantitative reconstructions of biomass burning deduced from stratified charcoal records from Europe, and South-, Central- and North America, and Oceania to test the fire-carbon release hypothesis. In Europe the significant increase of fire activity is dated ≈6000 cal. yr ago. In north-eastern North America burning activity was greatest before 7500 years ago, very low between 7500–3000 years, and has been increasing since 3000 years ago. In tropical America, the pattern is more complex and apparently latitudinally zonal. Maximum burning occurred in the southern Amazon basin and in Central America during the middle Holocene, and during the last 2000 years in the northern Amazon basin. In Oceania, biomass burning has decreased since a maximum 5000 years ago. Biomass burning has broadly increased in the Northern and Southern hemispheres throughout the second half of the Holocene associated with changes in climate and human practices. Global fire indices parallel the increase of atmospheric CO2 concentration recorded in Antarctic ice cores. Future issues on carbon dynamics relatively to biomass burning are discussed to improve the quantitative reconstructions.

Human impacts and aridity differentially alter soil N availability in drylands worldwide

Aims Climate and human impacts are changing the nitrogen (N) inputs and losses in terrestrial ecosystems. However, it is largely unknown how these two major drivers of global change will simultaneously influence the N cycle in drylands, the largest terrestrial biome on the planet. We conducted a global observational study to evaluate how aridity and human impacts, together with biotic and abiotic factors, affect key soil variables of the N cycle. Location Two hundred and twenty-four dryland sites from all continents except Antarctica widely differing in their environmental conditions and human influence. Methods Using a standardized field survey, we measured aridity, human impacts (i.e. proxies of land uses and air pollution), key biophysical variables (i.e. soil pH and texture and total plant cover) and six important variables related to N cycling in soils: total N, organic N, ammonium, nitrate, dissolved organic:inorganic N and N mineralization rates. We used structural equation modelling to assess the direct and indirect effects of aridity, human impacts and key biophysical variables on the N cycle. Results Human impacts increased the concentration of total N, while aridity reduced it. The effects of aridity and human impacts on the N cycle were spatially disconnected, which may favour scarcity of N in the most arid areas and promote its accumulation in the least arid areas. Main conclusions We found that increasing aridity and anthropogenic pressure are spatially disconnected in drylands. This implies that while places with low aridity and high human impact accumulate N, most arid sites with the lowest human impacts lose N. Our analyses also provide evidence that both increasing aridity and human impacts may enhance the relative dominance of inorganic N in dryland soils, having a negative impact on key functions and services provided by these ecosystems.

The ecoclimatology of Danum, Sabah, in the context of the world's rainforest regions, with particular reference to dry periods and their impact

Climatic records for Danum for 1985 to 1998, elsewhere in Sabah since 1879, and long monthly rainfall series from other rainforest locations are used to place the climate, and particularly the dry period climatology, of Danum into a world rainforest context. The magnitude frequency and seasonality of dry periods are shown to vary greatly within the world's rainforest zone. The climate of Danum, which is aseasonal but subject, as in 1997 to 1998, to occasional drought, is intermediate between less drought–prone north–western Borneo and the more drought–prone east coast. Changes through time in drought magnitude frequency in Sabah and rainforest locations elsewhere in South–East Asia and in the Neotropics are compared. The 1997 to 1998 ENSO–related drought event in Sabah is placed into a historical context. The effects of drought on tree growth and mortality in the tropics are assessed and a model relating intensity and frequency of drought disturbance to forest structure and composition is discussed.

Barriers and facilitators to nurses' acceptance of and implications for injury rates of an IV catheter safety device

This study has the purpose of determining the barriers and facilitators to nurses' acceptance of the Johnson and Johnson Protectiv®* Plus IV catheter safety needle device and implications for needlestick injuries at St. Luke's Episcopal Hospital, Houston, Texas. A one-time cross-sectional survey of 620 responding nurses was conducted by this researcher during December, 2000. The study objectives were to: (1) describe the perceived (a) organizational and individual barriers and facilitators and (b) acceptance of implementation of the IV catheter device; (2) examine the relative importance of these predictors; (3) describe (a) perceived changes in needlestick injuries after implementation of the device; (b) the reported incidence of injuries; and (c) the extent of underreporting by nurses; and (4) examine the relative importance of (a) the preceding predictors and (b) acceptance of the device in predicting perceived changes in needlestick injuries. Safety climate and training were evaluated as organizational factors. Individual factors evaluated were experience with the device, including time using it and frequency of use, and background information, including nursing unit, and length of time as a nurse in this hospital and in total nursing career. The conceptual framework was based upon the safety climate model. Descriptive statistics and multiple and logistic regression were utilized to address the study objectives. ^ The findings showed widespread acceptance of the device and a strong perception that it reduced the number of needlesticks. Acceptance was notably predicted by adequate training, appropriate time between training and device use, solid safety climate, and short length of service, in that order. A barrier to acceptance was nurses' longtime of use of previous needle technologies. Over four-fifths of nurses were compliant in always using the device. Compliance had two facilitators: length of time using device and, to a lesser extent, safety climate. Rates of compliance tended to be lower among nurses in units in which the device was frequently used. ^ High quality training and an atmosphere of caring about nurse safety stand out as primary facilitators that other institutions would need to adopt in order to achieve maximum success in implementing safety programs involving utilization of new safety devices. ^

Suspected outbreak of dengue fever in Houston: Clinical characteristics and determination of autochthonous transmission between 2003 and 2005

Houston, Texas maintains the appropriate climate and mosquito populations to support the circulation of dengue viruses. The city is susceptible to the introduction and subsequent local transmission of dengue virus with its proximity to dengue-endemic Mexico and the high degree of international travel routed through its airports. In 2008, a study at the University of Texas School of Public Health identified 58 suspected dengue fever cases that presented at hospitals and clinics in the Houston area. Serum or CSF samples of the 58 samples tested positive or equivocal for the presence of anti-dengue IgM antibodies (Rodriguez, 2008). Here, we present the results of an investigation aimed to describe the clinical characteristics of the 58 suspected dengue fever cases and to determine if local transmission had occurred. Data from medical record abstractions and personal telephone interviews were used to describe clinical characteristics and travel history of the suspected cases. Our analysis classified six probable dengue fever cases based on the case definition from the World Health Organization. Three of the probable cases for which we were able to obtain travel history had not recently traveled to an endemic area prior to onset of symptoms suggesting the illnesses were locally acquired in Houston. Further analysis led us to hypothesize that additional cases of dengue fever are present in our study population. Fifty-one percent of the study population was diagnosed with meningitis and/or encephalitis. Sixty percent of the individuals who received a lumbar puncture had abnormal CSF. Together these findings indicate viral infection with neurological involvement, which has been reported to occur with dengue fever. Among the individuals who received liver enzyme analysis, 54% had evidence of abnormal liver enzyme levels, a clinical sign commonly observed with dengue. Our results indicate that a suspected outbreak of dengue fever with autochthonous transmission occurred in the Houston area between 2003 and 2005. ^

Armstrong and Neely-Kinyon Research Farms Summary

Includes Farm and Weather Summary, Research Farm Projects, Acknowledgements and Information on Experiments in Previous Annual Progress Reports.

McNay Memorial Research and Demonstration Farm Summary

Includes Farm and Weather Summary and Research Farm Projects.

Ag Engineering and Agronomy Farm and Central Iowa Research Farms Summary

Includes Ag Engineering and Agronomy Farm Farm and Weather Summary, Central Iowa Farms Farm and Weather Summary and Project Lists

Armstrong and Neely-Kinyon Research Farms Summary

Includes Wallace Foundation for Rural Research and Development 2010 President's Report, Farm and Weather Summary, Research Farm Projects and Information on Experiments in Previous Annual Progress Reports.

Pollen records and age determinations from 2 profiles at Lake Nikolay, Lena Delta

Radiocarbon-dated pollen, rhizopod, chironomid and total organic carbon (TOC) records from Nikolay Lake (73°20'N, 124°12'E) and a pollen record from a nearby peat sequence are used for a detailed environmental reconstruction of the Holocene in the Lena Delta area. Shrubby Alnus fruticosa and Betula exilis tundra existed during 10,300-4800 cal. yr BP and gradually disappeared after that time. Climate reconstructions based on the pollen and chironomid records suggest that the climate during ca. 10,300-9200 cal. yr BP was up to 2-3 °C warmer than the present day. Pollen-based reconstructions show that the climate was relatively warm during 9200-6000 cal. yr BP and rather unstable between ca. 5800-3700 cal. yr BP. Both the qualitative interpretation of pollen data and the results of quantitative reconstruction indicate that climate and vegetation became similar to modern-day conditions after ca. 3600 cal. yr BP. The chironomid-based temperature reconstruction suggests a relatively warm period between ca. 2300 and 1400 cal. yr BP, which corresponds to the slightly warmer climate conditions reconstructed from the pollen. Modern chironomid and rhizopod assemblages were established after ca. 1400 cal. yr BP.