Response of alpine vegetation growth dynamics to snow cover phenology on the Tibetan Plateau

Science.gov (United States)

Wang, X.; Wu, C.

2017-12-01

Alpine vegetation plays a crucial role in global energy cycles with snow cover, an essential component of alpine land cover showing high sensitivity to climate change. The Tibetan Plateau (TP) has a typical alpine vegetation ecosystem and is rich of snow resources. With global warming, the snow of the TP has undergone significant changes that will inevitably affect the growth of alpine vegetation, but observed evidence of such interaction is limited. In particular, a comprehensive understanding of the responses of alpine vegetation growth to snow cover variability is still not well characterized on TP region. To investigate this, we calculated three indicators, the start (SOS) and length (LOS) of growing season, and the maximum of normalized difference vegetation index (NDVImax) as proxies of vegetation growth dynamics from the Moderate Resolution Imaging Spectroradiometer (MODIS) data for 2000-2015. Snow cover duration (SCD) and melt (SCM) dates were also extracted during the same time frame from the combination of MODIS and the Interactive Multi-sensor Snow and Ice Mapping System (IMS) data. We found that the snow cover phenology had a strong control on alpine vegetation growth dynamics. Furthermore, the responses of SOS, LOS and NDVImax to snow cover phenology varied among plant functional types, eco-geographical zones, and temperature and precipitation gradients. The alpine steppes showed a much stronger negative correlation between SOS and SCD, and also a more evidently positive relationship between LOS and SCD than other types, indicating a longer SCD would lead to an earlier SOS and longer LOS. Most areas showed positive correlation between SOS and SCM, while a contrary response was also found in the warm but drier areas. Both SCD and SCM showed positive correlations with NDVImax, but the relationship became weaker with the increase of precipitation. Our findings provided strong evidences between vegetation growth and snow cover phenology, and changes in

Contrasting growth responses of dominant peatland plants to warming and vegetation composition.

Science.gov (United States)

Walker, Tom N; Ward, Susan E; Ostle, Nicholas J; Bardgett, Richard D

2015-05-01

There is growing recognition that changes in vegetation composition can strongly influence peatland carbon cycling, with potential feedbacks to future climate. Nevertheless, despite accelerated climate and vegetation change in this ecosystem, the growth responses of peatland plant species to combined warming and vegetation change are unknown. Here, we used a field warming and vegetation removal experiment to test the hypothesis that dominant species from the three plant functional types present (dwarf-shrubs: Calluna vulgaris; graminoids: Eriophorum vaginatum; bryophytes: Sphagnum capillifolium) contrast in their growth responses to warming and the presence or absence of other plant functional types. Warming was accomplished using open top chambers, which raised air temperature by approximately 0.35 °C, and we measured air and soil microclimate as potential mechanisms through which both experimental factors could influence growth. We found that only Calluna growth increased with experimental warming (by 20%), whereas the presence of dwarf-shrubs and bryophytes increased growth of Sphagnum (46%) and Eriophorum (20%), respectively. Sphagnum growth was also negatively related to soil temperature, which was lower when dwarf-shrubs were present. Dwarf-shrubs may therefore promote Sphagnum growth by cooling the peat surface. Conversely, the effect of bryophyte presence on Eriophorum growth was not related to any change in microclimate, suggesting other factors play a role. In conclusion, our findings reveal contrasting abiotic and biotic controls over dominant peatland plant growth, suggesting that community composition and carbon cycling could be modified by simultaneous climate and vegetation change.

A Database of Herbaceous Vegetation Responses to Elevated Atmospheric CO{sub 2}

Energy Technology Data Exchange (ETDEWEB)

Jones, M.H.

1999-11-24

To perform a statistically rigorous meta-analysis of research results on the response by herbaceous vegetation to increased atmospheric CO{sub 2} levels, a multiparameter database of responses was compiled from the published literature. Seventy-eight independent CO{sub 2}-enrichment studies, covering 53 species and 26 response parameters, reported mean response, sample size, and variance of the response (either as standard deviation or standard error). An additional 43 studies, covering 25 species and 6 response parameters, did not report variances. This numeric data package accompanies the Carbon Dioxide Information Analysis Center's (CDIAC's) NDP-072, which provides similar information for woody vegetation. This numeric data package contains a 30-field data set of CO{sub 2}-exposure experiment responses by herbaceous plants (as both a flat ASCII file and a spreadsheet file), files listing the references to the CO{sub 2}-exposure experiments and specific comments relevant to the data in the data sets, and this documentation file (which includes SAS{reg_sign} and Fortran codes to read the ASCII data file). The data files and this documentation are available without charge on a variety of media and via the Internet from CDIAC.

Model-generated air quality statistics for application in vegetation response models in Alberta

International Nuclear Information System (INIS)

McVehil, G.E.; Nosal, M.

1990-01-01

To test and apply vegetation response models in Alberta, air pollution statistics representative of various parts of the Province are required. At this time, air quality monitoring data of the requisite accuracy and time resolution are not available for most parts of Alberta. Therefore, there exists a need to develop appropriate air quality statistics. The objectives of the work reported here were to determine the applicability of model generated air quality statistics and to develop by modelling, realistic and representative time series of hourly SO 2 concentrations that could be used to generate the statistics demanded by vegetation response models

Indonesian vegetation response to changes in rainfall seasonality over the past 25,000 years

Science.gov (United States)

Dubois, Nathalie; Oppo, Delia W.; Galy, Valier V.; Mohtadi, Mahyar; van der Kaars, Sander; Tierney, Jessica E.; Rosenthal, Yair; Eglinton, Timothy I.; Lückge, Andreas; Linsley, Braddock K.

2014-07-01

The hydrologic response to climate forcing in the Indo-Pacific warm pool region has varied spatially over the past 25,000 years. For example, drier conditions are inferred on Java and Borneo for the period following the end of the Last Glacial Maximum, whereas wetter conditions are reconstructed for northwest Australia. The response of vegetation to these past rainfall variations is poorly constrained. Using a suite of 30 surface marine sediment samples from throughout the Indo-Pacific warm pool, we demonstrate that today the stable isotopic composition of vascular plant fatty acids (δ13CFA) reflects the regional vegetation composition. This in turn is controlled by the seasonality of rainfall consistent with dry season water stress. Applying this proxy in a sediment core from offshore northeast Borneo, we show broadly similar vegetation cover during the Last Glacial Maximum and the Holocene, suggesting that, despite generally drier glacial conditions, there was no pronounced dry season. In contrast, δ13CFA and pollen data from a core off the coast of Sumba indicate an expansion of C4 herbs during the most recent glaciation, implying enhanced aridity and water stress during the dry season. Holocene vegetation trends are also consistent with a response to dry season water stress. We therefore conclude that vegetation in tropical monsoon regions is susceptible to increases in water stress arising from an enhanced seasonality of rainfall, as has occurred in past decades.

Using MODIS-NDVI for the Modeling of Post-Wildfire Vegetation Response as a Function of Environmental Conditions and Pre-Fire Restoration Treatments

Directory of Open Access Journals (Sweden)

Grant M. Casady

2012-03-01

Full Text Available Post-fire vegetation response is influenced by the interaction of natural and anthropogenic factors such as topography, climate, vegetation type and restoration practices. Previous research has analyzed the relationship of some of these factors to vegetation response, but few have taken into account the effects of pre-fire restoration practices. We selected three wildfires that occurred in Bandelier National Monument (New Mexico, USA between 1999 and 2007 and three adjacent unburned control areas. We used interannual trends in the Normalized Difference Vegetation Index (NDVI time series data derived from the Moderate Resolution Imaging Spectroradiometer (MODIS to assess vegetation response, which we define as the average potential photosynthetic activity through the summer monsoon. Topography, fire severity and restoration treatment were obtained and used to explain post-fire vegetation response. We applied parametric (Multiple Linear Regressions-MLR and non-parametric tests (Classification and Regression Trees-CART to analyze effects of fire severity, terrain and pre-fire restoration treatments (variable used in CART on post-fire vegetation response. MLR results showed strong relationships between vegetation response and environmental factors (p < 0.1, however the explanatory factors changed among treatments. CART results showed that beside fire severity and topography, pre-fire treatments strongly impact post-fire vegetation response. Results for these three fires show that pre-fire restoration conditions along with local environmental factors constitute key processes that modify post-fire vegetation response.

Response of spatial vegetation distribution in China to climate changes since the Last Glacial Maximum (LGM)

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Wang, Siyang; Xu, Xiaoting; Shrestha, Nawal; Zimmermann, Niklaus E.; Tang, Zhiyao; Wang, Zhiheng

2017-01-01

Analyzing how climate change affects vegetation distribution is one of the central issues of global change ecology as this has important implications for the carbon budget of terrestrial vegetation. Mapping vegetation distribution under historical climate scenarios is essential for understanding the response of vegetation distribution to future climatic changes. The reconstructions of palaeovegetation based on pollen data provide a useful method to understand the relationship between climate and vegetation distribution. However, this method is limited in time and space. Here, using species distribution model (SDM) approaches, we explored the climatic determinants of contemporary vegetation distribution and reconstructed the distribution of Chinese vegetation during the Last Glacial Maximum (LGM, 18,000 14C yr BP) and Middle-Holocene (MH, 6000 14C yr BP). The dynamics of vegetation distribution since the LGM reconstructed by SDMs were largely consistent with those based on pollen data, suggesting that the SDM approach is a useful tool for studying historical vegetation dynamics and its response to climate change across time and space. Comparison between the modeled contemporary potential natural vegetation distribution and the observed contemporary distribution suggests that temperate deciduous forests, subtropical evergreen broadleaf forests, temperate deciduous shrublands and temperate steppe have low range fillings and are strongly influenced by human activities. In general, the Tibetan Plateau, North and Northeast China, and the areas near the 30°N in Central and Southeast China appeared to have experienced the highest turnover in vegetation due to climate change from the LGM to the present. PMID:28426780

Holocene fire activity and vegetation response in South-Eastern Iberia

Science.gov (United States)

Gil-Romera, Graciela; Carrión, José S.; Pausas, Juli G.; Sevilla-Callejo, Miguel; Lamb, Henry F.; Fernández, Santiago; Burjachs, Francesc

2010-05-01

Since fire has been recognized as an essential disturbance in Mediterranean landscapes, the study of long-term fire ecology has developed rapidly. We have reconstructed a sequence of vegetation dynamics and fire changes across south-eastern Iberia by coupling records of climate, fire, vegetation and human activities. We calculated fire activity anomalies (FAAs) in relation to 3 ka cal BP for 10-8 ka cal BP, 6 ka cal BP, 4 ka cal BP and the present. For most of the Early to the Mid-Holocene uneven, but low fire events were the main vegetation driver at high altitudes where broadleaved and coniferous trees presented a highly dynamic post-fire response. At mid-altitudes in the mainland Segura Mountains, fire activity remained relatively stable, at similar levels to recent times. We hypothesize that coastal areas, both mountains and lowlands, were more fire-prone landscapes as biomass was more likely to have accumulated than in the inland regions, triggering regular fire events. The wet and warm phase towards the Mid-Holocene (between ca 8 and 6 ka cal BP) affected the whole region and promoted the spread of mesophytic forest co-existing with Pinus, as FAAs appear strongly negative at 6 ka cal BP, with a less important role of fire. Mid and Late Holocene landscapes were shaped by an increasing aridity trend and the rise of human occupation, especially in the coastal mountains where forest disappeared from ca 2 ka cal BP. Mediterranean-type vegetation (evergreen oaks and Pinus pinaster- halepensis types) showed the fastest post-fire vegetation dynamics over time.

Influence of vegetable diets on physiological and immune responses to thermal stress in Senegalese sole (Solea senegalensis)

DEFF Research Database (Denmark)

Conde-Sieira, Marta; Gesto, Manuel; Batista, Sónia

2018-01-01

quality parameters. However, scarce information is available regarding the long-term impact of vegetable diets (combining the inclusion of both vegetable protein and oils) on the stress response and immunity of this fish species. This study aims to evaluate the concomitant effect of the extended use...... of vegetable protein-based diets with fish oil (FO) replacement (0, 50 or 100%) by vegetable oils (VO), on the response to acute (10 min) or prolonged (4 days) stress, induced by thermal shock. Plasma levels of cortisol, glucose and lactate as well as hepatic levels of glucose, glycogen and lactate were......The substitution of fish resources as ingredients for aquafeeds by those based on vegetable sources is needed to ensure aquaculture sustainability in the future. It is known that Senegalese sole (Solea senegalensis) accepts high dietary content of plant ingredients without altering growth or flesh...

Fruit and vegetables consumption and incident hypertension: dose-response meta-analysis of prospective cohort studies.

Science.gov (United States)

Wu, L; Sun, D; He, Y

2016-10-01

The role of dietary factors on chronic diseases seems essential in the potentially adverse or preventive effects. However, no evidence of dose-response meta-analysis of prospective cohort studies has verified the association between the intake of fruit and/or vegetables and the risk of developing hypertension. The PubMed and Embase were searched for prospective cohort studies. A generic inverse-variance method with random effects model was used to calculate the pooled relative risks (RRs) and 95% confidence intervals (CIs). Generalized least squares trend estimation model was used to calculate the study-specific slopes for the dose-response analyses. Seven articles comprised nine cohorts involving 185 676 participants were assessed. The highest intake of fruit or vegetables separately, and total fruit and vegetables were inversely associated with the incident risk of hypertension compared with the lowest level, and the pooled RRs and 95% CIs were 0.87 (0.79, 0.95), 0.88 (0.79, 0.99) and 0.90 (0.84, 0.98), respectively. We also found an inverse dose-response relation between the risk of developing hypertension and fruit intake, and total fruit and vegetables consumption. The incident risk of hypertension was decreased by 1.9% for each serving per day of fruit consumption, and decreased by 1.2% for each serving per day of total fruit and vegetables consumption. Our results support the recommendation to increase the consumption of fruit and vegetables with respect to preventing the risk of developing hypertension. However, further large prospective studies and long-term high-quality randomized controlled trials are still needed to confirm the observed association.

Response of vegetation phenology to urbanization in the conterminous United States

Energy Technology Data Exchange (ETDEWEB)

Li, Xuecao [Department of Geological and Atmospheric Sciences, Iowa State University, Ames IA 50011 USA; Zhou, Yuyu [Department of Geological and Atmospheric Sciences, Iowa State University, Ames IA 50011 USA; Asrar, Ghassem R. [Pacific Northwest National Laboratory, Joint Global Change Research Institute, College Park MD 20740 USA; Mao, Jiafu [Climate Change Science Institute, Oak Ridge National Laboratory, Oak Ridge TN 37831 USA; Li, Xiaoma [Department of Geological and Atmospheric Sciences, Iowa State University, Ames IA 50011 USA; Li, Wenyu [Ministry of Education Key Laboratory for Earth System Modeling, Center for Earth System Science, Tsinghua University, Beijing 100084 China

2016-12-18

The influence of urbanization on vegetation phenology is gaining considerable attention due to its implications for human health, cycling of carbon and other nutrients in Earth system. In this study, we examined the relationship between change in vegetation phenology and urban size, an indicator of urbanization, for the conterminous United States. We studied more than 4500 urban clusters of varying size to determine the impact of urbanization on plant phenology, with the aids of remotely sensed observations since 2003–2012. We found that phenology cycle (changes in vegetation greenness) in rural areas starts earlier (start of season, SOS) and ends later (end of season, EOS), resulting in a longer growing season length (GSL), when compared to the respective surrounding urban areas. The average difference of GSL between urban and rural areas over all vegetation types, considered in this study, is about 9 days. Also, the extended GSL in urban area is consistent among different climate zones in the United States, whereas their magnitudes are varying across regions. We found that a tenfold increase in urban size could result in an earlier SOS of about 1.3 days and a later EOS of around 2.4 days. As a result, the GSL could be extended by approximately 3.6 days with a range of 1.6–6.5 days for 25th ~ 75th quantiles, with a median value of about 2.1 days. For different vegetation types, the phenology response to urbanization, as defined by GSL, ranges from 1 to 4 days. The quantitative relationship between phenology and urbanization is of great use for developing improved models of vegetation phenology dynamics under future urbanization, and for developing change indicators to assess the impacts of urbanization on vegetation phenology.

Simulated Vegetation Response to Climate Change in California: The Importance of Seasonal Production Patterns

Science.gov (United States)

Kim, J. B.; Pitts, B.

2013-12-01

MC1 dynamic global vegetation model simulates vegetation response to climate change by simulating vegetation production, soil biogeochemistry, plant biogeography and fire. It has been applied at a wide range of spatial scales, yet the spatio-temporal patterns of simulated vegetation production, which drives the model's response to climate change, has not been examined in detail. We ran MC1 for California at a relatively fine scale, 30 arc-seconds, for the historical period (1895-2006) and for the future (2007-2100), using downscaled data from four CMIP3-based climate projections: A2 and B1 GHG emissions scenarios simulated by PCM and GFDL GCMs. The use of these four climate projections aligns our work with a body of climate change research work commissioned by the California Public Interest Energy Research (PIER) Program. The four climate projections vary not only in terms of changes in their annual means, but in the seasonality of projected climate change. We calibrated MC1 using MODIS NPP data for 2000-2011 as a guide, and adapting a published technique for adjusting simulated vegetation production by increasing the simulated plant rooting depths. We evaluated the simulation results by comparing the model output for the historical period with several benchmark datasets, summarizing by EPA Level 3 Ecoregions. Multi-year summary statistics of model predictions compare moderately well with Kuchler's potential natural vegetation map, National Biomass and Carbon Dataset, Leenhouts' compilation of fire return intervals, and, of course, the MODIS NPP data for 2000-2011. When we compared MC1's monthly NPP values with MODIS monthly GPP data (2000-2011), however, the seasonal patterns compared very poorly, with NPP/GPP ratio for spring (Mar-Apr-May) often exceeding 1, and the NPP/GPP ratio for summer (Jun-Jul-Aug) often flattening to zero. This suggests MC1's vegetation production algorithms are overly biased for spring production at the cost of summer production. We

Vegetation Responses to Climate Variability in the Northern Arid to Sub-Humid Zones of Sub-Saharan Africa

Directory of Open Access Journals (Sweden)

Khaldoun Rishmawi

2016-11-01

Full Text Available In water limited environments precipitation is often considered the key factor influencing vegetation growth and rates of development. However; other climate variables including temperature; humidity; the frequency and intensity of precipitation events are also known to affect productivity; either directly by changing photosynthesis and transpiration rates or indirectly by influencing water availability and plant physiology. The aim here is to quantify the spatiotemporal patterns of vegetation responses to precipitation and to additional; relevant; meteorological variables. First; an empirical; statistical analysis of the relationship between precipitation and the additional meteorological variables and a proxy of vegetation productivity (the Normalized Difference Vegetation Index; NDVI is reported and; second; a process-oriented modeling approach to explore the hydrologic and biophysical mechanisms to which the significant empirical relationships might be attributed. The analysis was conducted in Sub-Saharan Africa; between 5 and 18°N; for a 25-year period 1982–2006; and used a new quasi-daily Advanced Very High Resolution Radiometer (AVHRR dataset. The results suggest that vegetation; particularly in the wetter areas; does not always respond directly and proportionately to precipitation variation; either because of the non-linearity of soil moisture recharge in response to increases in precipitation; or because variations in temperature and humidity attenuate the vegetation responses to changes in water availability. We also find that productivity; independent of changes in total precipitation; is responsive to intra-annual precipitation variation. A significant consequence is that the degree of correlation of all the meteorological variables with productivity varies geographically; so no one formulation is adequate for the entire region. Put together; these results demonstrate that vegetation responses to meteorological variation are more

Response of Competing Vegetation to Site Preparation on West Gulf Coastal Plain Commercial Forest Land

Science.gov (United States)

Gale L. Wolters; Henry A. Pearson; Ronald E. Thill; V. Clark Baldwin; Alton Martin

1995-01-01

The response of woody and herbaceous vegetation to site preparation, subsoil texture, and fertilization was measured on the West Gulf Coastal Plain. The influences of these treatments on competing vegetation were short-term. Drastic soil disturbance and fertilization briefly increased herbage production. Shear-windrow and shear-disk were generally the most effective...

Spectral response variation of a negative-electron-affinity photocathode in the preparation process

International Nuclear Information System (INIS)

Liu Lei; Du Yujie; Chang Benkang; Yunsheng Qian

2006-01-01

In order to research the spectral response variation of a negative electron affinity (NEA) photocathode in the preparation process, we have done two experiments on a transmission-type GaAs photocathode.First, an automatic spectral response recording system is described, which is used to take spectral response curves during the activation procedure of the photocathode. By this system, the spectral response curves of a GaAs:Cs-Ophotocathode measured in situ are presented. Then, after the cathode is sealed with a microchannel plate and a fluorescence screen into the image tube, we measure the spectral response of the tube by another measurement instrument. By way of comparing and analyzing these curves, we can find the typical variation in spectral-responses.The reasons for the variation are discussed. Based on these curves, spectral matching factors of a GaAs cathode for green vegetation and rough concrete are calculated. The visual ranges of night-vision goggles under specific circumstances are estimated. The results show that the spectral response of the NEA photocathode degraded in the sealing process, especially at long wavelengths. The variation has also influenced the whole performance of the intensifier tube

Soil Drought and Vegetation Response during 2001–2015 in North China Based on GLDAS and MODIS Data

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Siyao Yang

2018-01-01

Full Text Available Drought is a natural disaster caused by long-term water deficit. Because the growth of crops and vegetation is closely related to soil moisture environment, it is of great significance to study the soil drought and vegetation response. In this paper, the soil moisture availability index (SMAI was developed for quantifying soil drought conditions. The effectiveness and the ability of SMAI to recognize drought events were analyzed, while the vegetation condition index (VCI was used to characterize the vegetation status. Temporal and spatial variations of soil drought and vegetation condition as well as the impacts of drought on vegetation in North China during 2001–2015 were comprehensively examined. We firstly concluded that SMAI related well with standardized precipitation evapotranspiration index (SPEI, and drought events can be detected by SMAI. Next, the mean value of SMAI in North China showed a decreasing trend in recent 15 years. Finally, the SMAI positively correlated with VCI in most areas of North China, and the response of four types of vegetation to SMAI differed over time. The results of SMAI on vegetation would assist drought research and application in North China.

Notable shifting in the responses of vegetation activity to climate change in China

Science.gov (United States)

Chen, Aifang; He, Bin; Wang, Honglin; Huang, Ling; Zhu, Yunhua; Lv, Aifeng

The weakening relationship between inter-annual temperature variability and vegetation activity in the Northern Hemisphere over the last three decades has been reported by a recent study. However, how and to what extent vegetation activity responds to climate change in China is still unclear. We applied the Pearson correlation and partial correlation methods with a moving 15-y window to the GIMMS NDVI dataset from NOAA/AVHRR and observed climate data to examine the variation in the relationships between vegetation activity and climate variables. Results showed that there was an expanding negative response of vegetation growth to climate warming and a positive role of precipitation. The change patterns between NDVI and climate variables over vegetation types during the past three decades pointed an expending negative correlation between NDVI and temperature and a positive role of precipitation over most of the vegetation types (meadow, grassland, shrub, desert, cropland, and forest). Specifically, correlation between NDVI and temperature (PNDVI-T) have shifted from positive to negative in most of the station of temperature-limited areas with evergreen broadleaf forests, whereas precipitation-limited temperate grassland and desert were characterized by a positive PNDVI-P. This study contributes to ongoing investigations of the effects of climate change on vegetation activity. It is also of great importance for designing forest management strategies to cope with climate change.

A Modeling Approach for Evaluating the Coupled Riparian Vegetation-Geomorphic Response to Altered Flow Regimes

Science.gov (United States)

Manners, R.; Wilcox, A. C.; Merritt, D. M.

2016-12-01

The ecogeomorphic response of riparian ecosystems to a change in hydrologic properties is difficult to predict because of the interactions and feedbacks among plants, water, and sediment. Most riparian models of community dynamics assume a static channel, yet geomorphic processes strongly control the establishment and survival of riparian vegetation. Using a combination of approaches that includes empirical relationships and hydrodynamic models, we model the coupled vegetation-topographic response of three cross-sections on the Yampa and Green Rivers in Dinosaur National Monument, to a shift in the flow regime. The locations represent the variable geomorphology and vegetation composition of these canyon-bound rivers. We account for the inundation and hydraulic properties of vegetation plots surveyed over three years within International River Interface Cooperative (iRIC) Fastmech, equipped with a vegetation module that accounts for flexible stems and plant reconfiguration. The presence of functional groupings of plants, or those plants that respond similarly to environmental factors such as water availability and disturbance are determined from flow response curves developed for the Yampa River. Using field measurements of vegetation morphology, distance from the channel centerline, and dominant particle size and modeled inundation properties we develop an empirical relationship between these variables and topographic change. We evaluate vegetation and channel form changes over decadal timescales, allowing for the integration of processes over time. From our analyses, we identify thresholds in the flow regime that alter the distribution of plants and reduce geomorphic complexity, predominately through side-channel and backwater infilling. Simplification of some processes (e.g., empirically-derived sedimentation) and detailed treatment of others (e.g., plant-flow interactions) allows us to model the coupled dynamics of riparian ecosystems and evaluate the impact of

The influence of parent material on vegetation response 15 years after the Dude Fire, Arizona

Science.gov (United States)

Jackson M. Leonard; Alvin L. Medina; Daniel G. Neary; Aregai Tecle

2015-01-01

This study examined the effects of two types of parent material, sandstone and limestone, on the response of vegetation growth after the 1990 Dude Fire in central Arizona. The operating hypothesis of the study was that, given the right conditions, severe wildfire can trigger vegetation type conversion. Overall, three patterns emerged: (1) oak density increased by 413%...

Vegetation response to extreme climate events on the Mongolian Plateau from 2000 to 2010

International Nuclear Information System (INIS)

John, Ranjeet; Chen Jiquan; Ouyang Zutao; Becker, Richard; Xiao Jingfeng; Samanta, Arindam; Ganguly, Sangram; Yuan Wenping; Batkhishig, Ochirbat

2013-01-01

Climate change has led to more frequent extreme winters (aka, dzud) and summer droughts on the Mongolian Plateau during the last decade. Among these events, the 2000–2002 combined summer drought–dzud and 2010 dzud were the most severe on vegetation. We examined the vegetation response to these extremes through the past decade across the Mongolian Plateau as compared to decadal means. We first assessed the severity and extent of drought using the Tropical Rainfall Measuring Mission (TRMM) precipitation data and the Palmer drought severity index (PDSI). We then examined the effects of drought by mapping anomalies in vegetation indices (EVI, EVI2) and land surface temperature derived from MODIS and AVHRR for the period of 2000–2010. We found that the standardized anomalies of vegetation indices exhibited positively skewed frequency distributions in dry years, which were more common for the desert biome than for grasslands. For the desert biome, the dry years (2000–2001, 2005 and 2009) were characterized by negative anomalies with peak values between −1.5 and −0.5 and were statistically different (P 2 = 65 and 60, p 2 = 53, p < 0.05). Our results showed significant differences in the responses to extreme climatic events (summer drought and dzud) between the desert and grassland biomes on the Plateau. (letter)

Post-fire burn severity and vegetation response following eight large wildfires across the Western United States

Science.gov (United States)

Leigh B. Lentile; Penelope Morgan; Andrew T. Hudak; Michael J. Bobbitt; Sarah A. Lewis; Alistair M. S. Smith; Peter R. Robichaud

2007-01-01

Vegetation response and burn severity were examined following eight large wildfires that burned in 2003 and 2004: two wildfires in California chaparral, two each in dry and moist mixed-conifer forests in Montana, and two in boreal forests in interior Alaska. Our research objectives were: 1) to characterize one year post-fire vegetation recovery relative to initial fire...

Vegetative reproduction capacities of floodplain willows--cutting response to competition and biomass loss.

Science.gov (United States)

Radtke, A; Mosner, E; Leyer, I

2012-03-01

While several studies on regeneration in Salicaceae have focused on seedling recruitment, little is known about factors controlling their vegetative reproduction. In two greenhouse experiments, we studied the response of floodplain willows (Salix fragilis, S. viminalis, S. triandra) to competition with Poa trivialis, and to shoot and root removal when planted as vegetative cuttings. In the first experiment, growth performance variables were analysed in relation to full competition, shoot competition, root competition and control, taking into account two different water levels. After 9 weeks, shoots were removed and the resprouting capacity of the bare cuttings was recorded. In the second experiment, the cutting performance of the three floodplain and an additional two fen willow species (S. cinerea, S. aurita) was compared when grown in three different soil compositions and with two different water levels. After 9 weeks, shoot and root biomass was removed and the bare cuttings were replanted to test their ability to resprout. Cutting performance and secondary resprouting were negatively affected by full and shoot competition while root competition had no or weak effects. The floodplain species performed better than the fen species in all soil types and water levels. Secondary resprouting capacity was also higher in the floodplain species, which showed an additional strong positive response to the previous waterlogging treatment. The results contribute to understanding of the vegetative regeneration ecology of floodplain willows, and suggest that the use of vegetative plantings in restoration plantings could be an effective strategy for recovering floodplain forests. © 2011 German Botanical Society and The Royal Botanical Society of the Netherlands.

Climate and vegetation in a semi-arid savanna: Development of a climate–vegetation response model linking plant metabolic performance to climate and the effects on forage availability for large herbivores

Directory of Open Access Journals (Sweden)

Armin H. Seydack

2012-02-01

Developing the climate–vegetation response model involved three main components, namely (1 defining indicators of forage availability to herbivores (nitrogen productivity, nitrogen quality, carbon-nutrient quality, (2 identifying herbivore species guilds of similar nutritional requirements with respect to these indicators [bulk feeders with tolerance to fibrous herbage (buffalo, waterbuck, bulk feeders with preference for high nitrogen quality forage (short grass preference grazers: blue wildebeest and zebra and selective feeders where dietary items of relatively high carbon-nutrient quality represented key forage resources (selective grazers: sable antelope, roan antelope, tsessebe, eland] and (3 developing a process model where the expected effects of plant metabolic responses to climate on key forage resources were made explicit. According to the climate–vegetation response model both shorter-term transient temperature acclimation pulses and longer-term shifts in plant metabolic functionality settings were predicted to have occurred in response to temperature trends over the past century. These temperature acclimation responses were expected to have resulted in transient pulses of increased forage availability (increased nitrogen- and carbon-nutrient quality, as well as the progressive long-term decline of the carbon-nutrient quality of forage. Conservation implications: The climate–vegetation response model represents a research framework for further studies contributing towards the enhanced understanding of landscape-scale functioning of savanna systems with reference to the interplay between climate, vegetation and herbivore population dynamics. Gains in such understanding can support sound conservation management.

Using a Dynamic Global Vegetation Model to Simulate the Response of Vegetation to Warming at the Paleocene-Eocene Boundary

Science.gov (United States)

Shellito, C. J.; Sloan, L. C.

2004-12-01

A major turnover in benthic marine and terrestrial fauna marks the Initial Eocene Thermal Maximum (IETM) (~55Ma), a period of ~150 ky in which there was a rapid rise in deep sea and high latitude sea surface temperatures by 5-8C. Curiously, no major responses to this warming in the terrestrial floral record have been detected to date. Here, we present results from experiments examining the response of the global distribution of vegetation to changes in climate at the IETM using the NCAR Land Surface Model (LSM1.2) integrated with a dynamic global vegetation model (DGVM). DGVMs allow vegetation to respond to and interact with climate, and thus, provide a unique new method for addressing questions regarding feedbacks between the ecosystem and climate in Earth's past. However, there are a number of drawbacks to using these models that can affect interpretation of results. More specifically, these drawbacks involve uncertainties in the application of modern plant functional types to paleo-flora simulations, inaccuracies in the model climatology used to drive the DGVM, and lack of available detail regarding paleo-geography and paleo-soil type for use in model boundary conditions. For a better understanding of these drawbacks, we present results from a series of tests in the NCAR LSM-DGVM which examine (1) the effect of removing C4 grasses from the available plant functional types in the model; (2) model sensitivity to a change in soil texture; and (3), model sensitivity to a change in the value of pCO2 used in the photosynthetic rate equations. We consider our DGVM results for the IETM in light of output from these sensitivity experiments.

Response of Vegetation on Gravel Bars to Management Measures and Floods: Case Study From the Czech Republic

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Eremiášová Renata

2014-08-01

Full Text Available This article investigates response of vegetation on gravel bars to management measures and floods. The management measures consisted of the partial removal of gravel and vegetation cover, and were applied to six gravel bars on the Ostravice River, Czech Republic. Unexpected floods occu-rred in 2010, with the amplitude of 5- to 50-year repetition. Research of vegetation on the gravel bars consisted of vegetation survey before the management works; the monitoring of vegetation development over the following year and the verification of the relationships of species diversity, successional stages and the biotope conditions with the help of multivariate analysis (detrended correspondence analysis. Vegetation on the gravel bars was at different successional stages, and had higher diversity and vegetation cover before the management measures and floods. The mul-tivariate analysis revealed a shift toward initial successional stages with high demand on moisture, temperature and light after both management measures and floods.

Ecosystem properties self-organize in response to a directional fog-vegetation interaction.

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Stanton, Daniel E; Armesto, Juan J; Hedin, Lars O

2014-05-01

Feedbacks between vegetation and resource inputs can lead to the local, self-organization of ecosystem properties. In particular, feedbacks in response to directional resources (e.g., coastal fog, slope runoff) can create complex spatial patterns, such as vegetation banding. Although similar feedbacks are thought to be involved in the development of ecosystems, clear empirical examples are rare. We created a simple model of a fog-influenced, temperate rainforest in central Chile, which allows the comparison of natural banding patterns to simulations of various putative mechanisms. We show that only feedbacks between plants and fog were able to replicate the characteristic distributions of vegetation, soil water, and soil nutrients observed in field transects. Other processes, such as rainfall, were unable to match these diagnostic distributions. Furthermore, fog interception by windward trees leads to increased downwind mortality, leading to progressive extinction of the leeward edge. This pattern of ecosystem development and decay through self-organized processes illustrates, on a relatively small spatial and temporal scale, the patterns predicted for ecosystem evolution.

Response of vegetable organisms to quasi-monochromatic light of different duration, intensity and wavelength

Energy Technology Data Exchange (ETDEWEB)

Budagovsky, A V; Solovykh, N V [I.V.Michurin All-Russian Recearch Institute of Fruit Crops Genetics and Breeding (Russian Federation); Budagovskaya, O N [I.V.Michurin All-Russia Research and Development Institute of Gardening, Michurinsk, Tambov region (Russian Federation); Budagovsky, I A [P N Lebedev Physics Institute, Russian Academy of Sciences, Moscow (Russian Federation)

2015-04-30

By the example of vegetable organisms differing in structure and functional properties it is shown that their response to the action of quasi-monochromatic light from laser sources does not obey the Bunsen – Roscoe dose law. The dependence of biological effect on the irradiation time has the multimodal (multiextremal) form with alternating maxima and minima of the stimulating effect. Such a property manifests itself in the spectral ranges, corresponding to photoinduced conversion of chromoproteins of photocontrol systems and is probably related to the cyclic variations of metabolic activity in vegetable cells. (biophotonics)

A Comparison of Response Rate, Response Time, and Costs of Mail and Electronic Surveys.

Science.gov (United States)

Shannon, David M.; Bradshaw, Carol C.

2002-01-01

Compared response rates, response time, and costs of mail and electronic surveys using a sample of 377 college faculty members. Mail surveys yielded a higher response rate and a lower rate of undeliverable surveys, but response time was longer and costs were higher than for electronic surveys. (SLD)

Critical impact of vegetation physiology on the continental hydrologic cycle in response to increasing CO2

Science.gov (United States)

Lemordant, Léo; Gentine, Pierre; Swann, Abigail S.; Cook, Benjamin I.; Scheff, Jacob

2018-04-01

Predicting how increasing atmospheric CO2 will affect the hydrologic cycle is of utmost importance for a range of applications ranging from ecological services to human life and activities. A typical perspective is that hydrologic change is driven by precipitation and radiation changes due to climate change, and that the land surface will adjust. Using Earth system models with decoupled surface (vegetation physiology) and atmospheric (radiative) CO2 responses, we here show that the CO2 physiological response has a dominant role in evapotranspiration and evaporative fraction changes and has a major effect on long-term runoff compared with radiative or precipitation changes due to increased atmospheric CO2. This major effect is true for most hydrological stress variables over the largest fraction of the globe, except for soil moisture, which exhibits a more nonlinear response. This highlights the key role of vegetation in controlling future terrestrial hydrologic response and emphasizes that the carbon and water cycles are intimately coupled over land.

The responses of net primary production (NPP) and total carbon storage for the continental United States to changes in atmospheric CO{sub 2}, climate, and vegetation

Energy Technology Data Exchange (ETDEWEB)

McGuire, D.A. [Marine Biological Lab., Woods Hole, MA (United States)

1995-06-01

We extrapolated 3 biogeochemistry models (BIOME-BGC, CENTURY, and TEM) across the continental US with the vegetation distributions of 3 biogeography models (BIOME2, DOLY, and MAPSS) for contemporary climate at 355 ppmv CO{sub 2} and each of 3 GCM climate scenarios at 710 ppmv. For contemporary conditions, continental NPP ranges from 3132 to 3854 TgC/yr and total carbon storage ranges from 109 to 125 PgC. The responses of NPP range from no response (BIOME-BGC with DOLY or MAPSS vegetations for UKMO climate) to increases of 53% and 56% (TEM with BIOME2 vegetations for GFDL and OSU climates). The responses of total carbon storage vary from a decrease of 39% (BIOME-BGC with MAPSS vegetation for UKMO climate) to increases of 52% and 56% (TEM with BIOME2 vegetations for OSU and GFDL climates). The UKMO responses of BIOME-BGC with MAPSS vegetation are caused by both decreased forest area (from 44% to 38%) and photosynthetic water stress. The OSU and GFDL responses of TEM with BIOME2 vegetations are caused by forest expansion (from 46% to 67% for OSU and to 75% for GFDL) and increased nitrogen cycling.

Salt marsh recovery from a crude oil spill: Vegetation, oil weathering, and response

International Nuclear Information System (INIS)

Hoff, R.Z.; Shigenaka, G.; Henry, C.B. Jr.

1993-01-01

When a spill of Prudhoe Bay crude oil covered a fringing Salicornia virginica marsh in Fidalgo Bay, Washington (northern Puget Sound) in February 1991, response personnel used several low-impact techniques to remove oil from the marsh, and minimized access by cleanup workers. Following the response, a monitoring program was established to track marsh recovery, and to document the effectiveness of the response techniques used and their impacts on the marsh. Through monthly sampling over a 16-month period, vegetative growth was monitored and chemical degradation of remaining oil was tracked. Sampling was conducted along transects located in four areas affected in different ways by the spill, including an oiled, trampled section; an oiled, vacuumed section; and an oiled, washed, and vacuumed section. In addition, a control transect was established in an unoiled adjacent marsh. The study included both biological and chemical components. Biological measurements included percent cover of live vegetation (sampled monthly) and below-ground plant biomass (sampled at the beginning of each growing season in April 1991 and April 1992). Sediment samples included surface sediment (monthly) and core samples collected at the beginning and end of the growing seasons. Sediment samples were analyzed using gas chromatography/mass spectroscopy, and indicator compounds were tracked to determine rates of oil degradation. Results from 16 months of post-spill monitoring show that foot trampling was most detrimental to marsh plants, while washing with vacuuming removed the most oil and minimized adverse impacts to vegetation. Dense clay substrate helped prevent oil from penetrating the sediment, thus minimizing acute toxic effects from oil exposure to marsh plant rootstock. By the second growing season post-spill, Salicornia and other marsh plants were growing in all areas except one heavily oiled patch

Cortical responses to salient nociceptive and not nociceptive stimuli in vegetative and minimal conscious state

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de Tommaso, Marina; Navarro, Jorge; Lanzillotti, Crocifissa; Ricci, Katia; Buonocunto, Francesca; Livrea, Paolo; Lancioni, Giulio E.

2015-01-01

Aims: Questions regarding perception of pain in non-communicating patients and the management of pain continue to raise controversy both at a clinical and ethical level. The aim of this study was to examine the cortical response to salient visual, acoustic, somatosensory electric non-nociceptive and nociceptive laser stimuli and their correlation with the clinical evaluation. Methods: Five Vegetative State (VS), 4 Minimally Conscious State (MCS) patients and 11 age- and sex-matched controls were examined. Evoked responses were obtained by 64 scalp electrodes, while delivering auditory, visual, non-noxious electrical and noxious laser stimulation, which were randomly presented every 10 s. Laser, somatosensory, auditory and visual evoked responses were identified as a negative-positive (N2-P2) vertex complex in the 500 ms post-stimulus time. We used Nociception Coma Scale-Revised (NCS-R) and Coma Recovery Scale (CRS-R) for clinical evaluation of pain perception and consciousness impairment. Results: The laser evoked potentials (LEPs) were recognizable in all cases. Only one MCS patient showed a reliable cortical response to all the employed stimulus modalities. One VS patient did not present cortical responses to any other stimulus modality. In the remaining participants, auditory, visual and electrical related potentials were inconstantly present. Significant N2 and P2 latency prolongation occurred in both VS and MCS patients. The presence of a reliable cortical response to auditory, visual and electric stimuli was able to correctly classify VS and MCS patients with 90% accuracy. Laser P2 and N2 amplitudes were not correlated with the CRS-R and NCS-R scores, while auditory and electric related potentials amplitude were associated with the motor response to pain and consciousness recovery. Discussion: pain arousal may be a primary function also in vegetative state patients while the relevance of other stimulus modalities may indicate the degree of cognitive and motor

Ultrafast electron microscopy: Instrument response from the single-electron to high bunch-charge regimes

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Plemmons, Dayne A.; Flannigan, David J.

2017-09-01

We determine the instrument response of an ultrafast electron microscope equipped with a conventional thermionic electron gun and absent modifications beyond the optical ports. Using flat, graphite-encircled LaB6 cathodes, we image space-charge effects as a function of photoelectron-packet population and find that an applied Wehnelt bias has a negligible effect on the threshold levels (>103 electrons per pulse) but does appear to suppress blurring at the upper limits (∼105 electrons). Using plasma lensing, we determine the instrument-response time for 700-fs laser pulses and find that single-electron packets are laser limited (1 ps), while broadening occurs well below the space-charge limit.

Vegetation responses to sagebrush-reduction treatments measured by satellites

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Johnston, Aaron; Beever, Erik; Merkle, Jerod A.; Chong, Geneva W.

2018-01-01

Time series of vegetative indices derived from satellite imagery constitute tools to measure ecological effects of natural and management-induced disturbances to ecosystems. Over the past century, sagebrush-reduction treatments have been applied widely throughout western North America to increase herbaceous vegetation for livestock and wildlife. We used indices from satellite imagery to 1) quantify effects of prescribed-fire, herbicide, and mechanical treatments on vegetative cover, productivity, and phenology, and 2) describe how vegetation changed over time following these treatments. We hypothesized that treatments would increase herbaceous cover and accordingly shift phenologies towards those typical of grass-dominated systems. We expected prescribed burns would lead to the greatest and most-prolonged effects on vegetative cover and phenology, followed by herbicide and mechanical treatments. Treatments appeared to increase herbaceous cover and productivity, which coincided with signs of earlier senescence − signals expected of grass-dominated systems, relative to sagebrush-dominated systems. Spatial heterogeneity for most phenometrics was lower in treated areas relative to controls, which suggested treatment-induced homogenization of vegetative communities. Phenometrics that explain spring migrations of ungulates mostly were unaffected by sagebrush treatments. Fire had the strongest effect on vegetative cover, and yielded the least evidence for sagebrush recovery. Overall, treatment effects were small relative to those reported from field-based studies for reasons most likely related to sagebrush recovery, treatment specification, and untreated patches within mosaicked treatment applications. Treatment effects were also small relative to inter-annual variation in phenology and productivity that was explained by temperature, snowpack, and growing-season precipitation. Our results indicated that cumulative NDVI, late-season phenometrics, and spatial

Studying the Post-Fire Response of Vegetation in California Protected Areas with NDVI-based Pheno-Metrics

Science.gov (United States)

Jia, S.; Gillespie, T. W.

2016-12-01

Post-fire response from vegetation is determined by the intensity and timing of fires as well as the nature of local biomes. Though the field-based studies focusing on selected study sites helped to understand the mechanisms of post-fire response, there is a need to extend the analysis to a broader spatial extent with the assistance of remotely sensed imagery of fires and vegetation. Pheno-metrics, a series of variables on the growing cycle extracted from basic satellite measurements of vegetation coverage, translate the basic remote sensing measurements such as NDVI to the language of phenology and fire ecology in a quantitative form. In this study, we analyzed the rate of biomass removal after ignition and the speed of post-fire recovery in California protected areas from 2000 to 2014 with USGS MTBS fire data and USGS eMODIS pheno-metrics. NDVI drop caused by fire showed the aboveground biomass of evergreen forest was removed much slower than shrubland because of higher moisture level and greater density of fuel. In addition, the above two major land cover types experienced a greatly weakened immediate post-fire growing season, featuring a later start and peak of season, a shorter length of season, and a lower start and peak of NDVI. Such weakening was highly correlated with burn severity, and also influenced by the season of fire and the land cover type, according to our modeling between the anomalies of pheno-metrics and the difference of normalized burn ratio (dNBR). The influence generally decayed over time, but can remain high within the first 5 years after fire, mostly because of the introduction of exotic species when the native species were missing. Local-specific variables are necessary to better address the variance within the same fire and improve the outcomes of models. This study can help ecologists in validating the theories of post-fire vegetation response mechanisms and assist local fire managers in post-fire vegetation recovery.

Response of vegetable seed germination to solar radiation penetrating through soil

International Nuclear Information System (INIS)

Hamamoto, H.

1999-01-01

Response of vegetable seeds to irradiation and emergence of plants seeded at various depths were investigated to clarify the effects of solar radiation through soil on vegetable seed germination. Seeds of eight vegetable species were germinated in Petri dishes under 11-h irradiation per day. Seed germination was delayed in tomato (Licopersicon esculentum Mill.) but accelerated in perilla (Perilla ocymoides L.) and Japanese hornwort (Cryptotaenia japonica Hassk.) with increase in irradiation at the intensities higher than 0.4W m -2 . Seeds of Japanese radish (Raphanus sativus L.), watermelon (Citrullus lanatus Matsum.), and Chinese cabbage (Brassica campestris L.) showed delayed germination at more than 4-6W m -2 . No effect of irradiation on lettuce (Lactuca sativa L.) and carrot (Daucus carota L.) seed germination was seen. For tomato, Japanese radish and Japanese hornwort, the effects of irradiation time on germination were also investigated. Tomato seed germination was delayed and Japanese hornwort seed germination was accelerated with increase in irradiation time beyond 2h per day. The emergence of tomato and Japanese hornwort covered with Shimokuriyagawa loam soil (Kuriyagawa soil) and vermiculite at depths of less than 5mm, 5-10mm and 10-15mm was observed. Plants emerged more rapidly from 5-10mm depths than from less than 5mm depth in tomato. The plants seeded at 10-15mm depths emerged as rapidly as those at 5-10mm depths using vermiculite but later than those at other depths using Kuriyagawa soil, probably due to high bulk density. The early emergence of Japanese hornwort was fastest from less than 5mm depth. The plants seeded at 5-10mm depths did not emerge much slower than those at less than 5mm depth. A seeding depth of 5-10mm was suitable for the rapid emergence of those vegetables covered with both the soil and vermiculite. (author)

Forest Vegetation Simulator translocation techniques with the Bureau of Land Management's Forest Vegetation Information system database

Science.gov (United States)

Timothy A. Bottomley

2008-01-01

The BLM uses a database, called the Forest Vegetation Information System (FORVIS), to store, retrieve, and analyze forest resource information on a majority of their forested lands. FORVIS also has the capability of easily transferring appropriate data electronically into Forest Vegetation Simulator (FVS) for simulation runs. Only minor additional data inputs or...

Vegetation productivity responses to drought on tribal lands in the four corners region of the Southwest USA

Science.gov (United States)

El-Vilaly, Mohamed Abd Salam; Didan, Kamel; Marsh, Stuart E.; van Leeuwen, Willem J. D.; Crimmins, Michael A.; Munoz, Armando Barreto

2018-03-01

For more than a decade, the Four Corners Region has faced extensive and persistent drought conditions that have impacted vegetation communities and local water resources while exacerbating soil erosion. These persistent droughts threaten ecosystem services, agriculture, and livestock activities, and expose the hypersensitivity of this region to inter-annual climate variability and change. Much of the intermountainWestern United States has sparse climate and vegetation monitoring stations, making fine-scale drought assessments difficult. Remote sensing data offers the opportunity to assess the impacts of the recent droughts on vegetation productivity across these areas. Here, we propose a drought assessment approach that integrates climate and topographical data with remote sensing vegetation index time series. Multisensor Normalized Difference Vegetation Index (NDVI) time series data from 1989 to 2010 at 5.6 km were analyzed to characterize the vegetation productivity changes and responses to the ongoing drought. A multi-linear regression was applied to metrics of vegetation productivity derived from the NDVI time series to detect vegetation productivity, an ecosystem service proxy, and changes. The results show that around 60.13% of the study area is observing a general decline of greenness ( pchallenges to the region's already stressed ecosystems. Whereas the results provide additional insights into this isolated and vulnerable region, the drought assessment approach used in this study may be adapted for application in other regions where surface-based climate and vegetation monitoring record is spatially and temporally limited.

Vegetation Changes in the Permafrost Regions of the Qinghai-Tibetan Plateau from 1982-2012: Different Responses Related to Geographical Locations and Vegetation Types in High-Altitude Areas.

Directory of Open Access Journals (Sweden)

Zhiwei Wang

Full Text Available The Qinghai-Tibetan Plateau (QTP contains the largest permafrost area in a high-altitude region in the world, and the unique hydrothermal environments of the active layers in this region have an important impact on vegetation growth. Geographical locations present different climatic conditions, and in combination with the permafrost environments, these conditions comprehensively affect the local vegetation activity. Therefore, the responses of vegetation to climate change in the permafrost region of the QTP may be varied differently by geographical location and vegetation condition. In this study, using the latest Global Inventory Modeling and Mapping Studies (GIMMS Normalized Difference Vegetation Index (NDVI product based on turning points (TPs, which were calculated using a piecewise linear model, 9 areas within the permafrost region of the QTP were selected to investigate the effect of geographical location and vegetation type on vegetation growth from 1982 to 2012. The following 4 vegetation types were observed in the 9 selected study areas: alpine swamp meadow, alpine meadow, alpine steppe and alpine desert. The research results show that, in these study areas, TPs mainly appeared in 2000 and 2001, and almost 55.1% and 35.0% of the TPs were located in 2000 and 2001. The global standardized precipitation evapotranspiration index (SPEI and 7 meteorological variables were selected to analyze their correlations with NDVI. We found that the main correlative variables to vegetation productivity in study areas from 1982 to 2012 were precipitation, surface downward long-wave radiation and temperature. Furthermore, NDVI changes exhibited by different vegetation types within the same study area followed similar trends. The results show that regional effects rather than vegetation type had a larger impact on changes in vegetation growth in the permafrost regions of the QTP, indicating that climatic factors had a larger impact in the permafrost

Responses of sri lankan traditional rice to photoperiod at early vegetative stage

International Nuclear Information System (INIS)

Rathnathunga, U.U.E.; Geekiyanage, S.

2017-01-01

Rice is a photoperiod sensitive plant for flowering initiation. Effect of photoperiod can be important in vegetative growth and yield determination in rice. The objective of the research was to determine the effect of photoperiod on the vegetative responses of Sri Lankan traditional rice germplasm (SLTRG). Forty five traditional rice accessions (TRA), 5 improved rice varieties (IR), Sri Lankan wild rice (Oryza nivara and Oryza rufipogan) and Oryza japonica accessions 6782 and 6752 were grown in short day (SD), day neutral (DN) and long day (LD) conditions. Days to reach the fifth leaf stage (DFL), plant height (PH) and tiller number (TN) at the fifth leaf stage were recorded. Twenty three genotypes including 21 TRA, Oryza japonica 6752 and Oryza nivara did not respond to photoperiod having non-significant values for DFL, PH and TN among photoperiods. The DFL was affected in 25 genotypes; among them both DFL and PH were affected in 7 genotypes. DFL was significantly increased during LD in 4 TRA while DFL was significantly reduced in all 5 IR and 5 TRA. DFL was significantly increased in Oryza japonica 6782 and 5 TRA under SD. In 4 TRA, DFL was reduced under SD. The TN was affected in Oryza japonica 6782 only under SD with increased DFL. The DFL was significantly increased under DN in Oryza rufipogan, 5 TRA and 2 IR. Both SD and LD photoperiods differently affected the interaction between DFL and PH in TRA while only LD affected that of IR. DN had an effect on the interaction between DFL and PH only in wild rice Oryza rufipogon. Variation of vegetative growth response to photoperiod may depict the wide genetic basis of SLTRG. (author)

Nile Basin Vegetation Response and Vulnerability to Climate Change: A Multi-Sensor Remote Sensing Approach

Science.gov (United States)

Yitayew, M.; Didan, K.; Barreto-munoz, A.

2013-12-01

changes in the vegetation index signal and to a lesser degree the change in land cover and land use over the last 30 years. Using the climate data record we looked at the drivers of this change. The sensitivity of the basin to climate change was assessed using the multi-linear regression analysis on the covariance of the change in key phenology parameters and the two climate drivers considered here. The overall response was very complex owing to the complicated climate regime and topography of the region. Vegetation response was mostly stable in high lands with a slightly decreasing trend over low and mid-elevations. Over the same period we also observed an intensification of agriculture production corresponding to an increase in percent cover and productivity. We also observed a decrease in forest cover associated with land use conversion. These changes were mostly driven by the precipitation regimes with little impact of the temperature. Climate models project an eventual decrease in precipitation and increase in temperature over the basin. Coupled with these results and observations these projected changes point to major challenges to the vegetation cover, productivity, and associated ecosystem services of the Nile basin.

Responses of Vegetation Growth to Climatic Factors in Shule River Basin in Northwest China: A Panel Analysis

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Jinghui Qi

2017-03-01

Full Text Available The vegetation response to climatic factors is a hot topic in global change research. However, research on vegetation in Shule River Basin, which is a typical arid region in northwest China, is still limited, especially at micro scale. On the basis of Moderate-resolution Imaging Spectroradiometer (MODIS Normalized Difference Vegetation Index (NDVI data and daily meteorological data, employing panel data models and other mathematical models, the aim of this paper is to reveal the interactive relationship between vegetation variation and climatic factors in Shule River Basin. Results show that there is a widespread greening trend in the whole basin during 2000–2015, and 80.28% of greening areas (areas with vegetation improvement are distributed over upstream region, but the maximum vegetation variation appears in downstream area. The effects of climate change on NDVI lag about half to one month. The parameters estimated using panel data models indicate that precipitation and accumulated temperature have positive contribution to NDVI. With every 1-mm increase in rainfall, NDVI increases by around 0.223‰ in upstream area and 0.6‰ in downstream area. With every 1-°C increase in accumulated temperature, NDVI increases by around 0.241‰ in upstream area and 0.174‰ in downstream area. Responses of NDVI to climatic factors are more sensitive when these factors are limiting than when they are not limiting. NDVI variation has performance in two seasonal and inter-annual directions, and the range of seasonal change is far more than that of inter-annual change. The inverted U-shaped curve of the variable intercepts reflects the seasonal change. Our results might provide some scientific basis for the comprehensive basin management.

Climatic drivers of vegetation based on wavelet analysis

Science.gov (United States)

Claessen, Jeroen; Martens, Brecht; Verhoest, Niko E. C.; Molini, Annalisa; Miralles, Diego

2017-04-01

Vegetation dynamics are driven by climate, and at the same time they play a key role in forcing the different bio-geochemical cycles. As climate change leads to an increase in frequency and intensity of hydro-meteorological extremes, vegetation is expected to respond to these changes, and subsequently feed back on their occurrence. This response can be analysed using time series of different vegetation diagnostics observed from space, in the optical (e.g. Normalised Difference Vegetation Index (NDVI), Solar Induced Fluorescence (SIF)) and microwave (Vegetation Optical Depth (VOD)) domains. In this contribution, we compare the climatic drivers of different vegetation diagnostics, based on a monthly global data-cube of 24 years at a 0.25° resolution. To do so, we calculate the wavelet coherence between each vegetation-related observation and observations of air temperature, precipitation and incoming radiation. The use of wavelet coherence allows unveiling the scale-by-scale response and sensitivity of the diverse vegetation indices to their climatic drivers. Our preliminary results show that the wavelet-based statistics prove to be a suitable tool for extracting information from different vegetation indices. Going beyond traditional methods based on linear correlations, the application of wavelet coherence provides information about: (a) the specific periods at which the correspondence between climate and vegetation dynamics is larger, (b) the frequencies at which this correspondence occurs (e.g. monthly or seasonal scales), and (c) the time lag in the response of vegetation to their climate drivers, and vice versa. As expected, areas of high rainfall volumes are characterised by a strong control of radiation and temperature over vegetation. Furthermore, precipitation is the most important driver of vegetation variability over short terms in most regions of the world - which can be explained by the rapid response of leaf development towards available water content

Increasing fruit and vegetable consumption among schoolchildren: efforts in middle-income countries.

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Wijesinha-Bettoni, Ramani; Orito, Aya; Löwik, Marianne; Mclean, Catherine; Muehlhoff, Ellen

2013-03-01

To reverse the trend of rising child obesity rates in many middle-income countries, recommendations include increasing fruit and vegetable consumption. Schools can positively impact children's eating behavior, and multicomponent interventions that include the curriculum, school food environments, and parental involvement are most effective. To find out how fruits and vegetables feature in the dietary guidelines provided to schools, what specific schemes are available for providing these foods, the extent to which nutrition education is included in the curriculum, and how vegetables and fruits are procured in primary schools. In 2008, a survey questionnaire previously validated and revised was sent electronically to national program managers and focal points for school feeding programs in 58 middle-income countries. The rationale was to obtain information relevant to the entire country from these key informants. The survey response rate was 46%. The information provided by 22 respondents in 18 countries was included in the current study. On average, respondents answered 88% of the questions analyzed in this paper. Of the respondents, 73% worked for the national authority responsible for school food programs, with 45% at the program coordinator or director level. Few countries have any special fruit and vegetable schemes; implementation constraints include cost and lack of storage facilities. Although 11 of 18 countries have both nutrient-based guidelines and school food guidelines for meals, fruits and vegetables are often not adequately specified. In some countries, nutrition education, special activities, school gardens, and parental participation are used to promote fruits and vegetables. Specific schemes are needed in some, together with school food guidelines that include fruits and vegetables.

Smart plants, smart models? On adaptive responses in vegetation-soil systems

Science.gov (United States)

van der Ploeg, Martine; Teuling, Ryan; van Dam, Nicole; de Rooij, Gerrit

2015-04-01

Hydrological models that will be able to cope with future precipitation and evapotranspiration regimes need a solid base describing the essence of the processes involved [1]. The essence of emerging patterns at large scales often originates from micro-behaviour in the soil-vegetation-atmosphere system. A complicating factor in capturing this behaviour is the constant interaction between vegetation and geology in which water plays a key role. The resilience of the coupled vegetation-soil system critically depends on its sensitivity to environmental changes. To assess root water uptake by plants in a changing soil environment, a direct indication of the amount of energy required by plants to take up water can be obtained by measuring the soil water potential in the vicinity of roots with polymer tensiometers [2]. In a lysimeter experiment with various levels of imposed water stress the polymer tensiometer data suggest maize roots regulate their root water uptake on the derivative of the soil water retention curve, rather than the amount of moisture alone. As a result of environmental changes vegetation may wither and die, or these changes may instead trigger gene adaptation. Constant exposure to environmental stresses, biotic or abiotic, influences plant physiology, gene adaptations, and flexibility in gene adaptation [3-7]. To investigate a possible relation between plant genotype, the plant stress hormone abscisic acid (ABA) and the soil water potential, a proof of principle experiment was set up with Solanum Dulcamare plants. The results showed a significant difference in ABA response between genotypes from a dry and a wet environment, and this response was also reflected in the root water uptake. Adaptive responses may have consequences for the way species are currently being treated in models (single plant to global scale). In particular, model parameters that control root water uptake and plant transpiration are generally assumed to be a property of the plant

Understory vegetation response to mechanical mastication and other fuels treatments in a ponderosa pine forest

Science.gov (United States)

Jeffrey M. Kane; J. Morgan Varner; Eric E. Knapp

2010-01-01

Questions: What influence does mechanical mastication and other fuel treatments have on: (1) canopy and forest floor response variables that influence understory plant development; (2) initial understory vegetation cover, diversity, and composition; and (3) shrub and non-native species density in a secondgrowth ponderosa pine forest....

Complex responses of spring alpine vegetation phenology to snow cover dynamics over the Tibetan Plateau, China.

Science.gov (United States)

Wang, Siyuan; Wang, Xiaoyue; Chen, Guangsheng; Yang, Qichun; Wang, Bin; Ma, Yuanxu; Shen, Ming

2017-09-01

Snow cover dynamics are considered to play a key role on spring phenological shifts in the high-latitude, so investigating responses of spring phenology to snow cover dynamics is becoming an increasingly important way to identify and predict global ecosystem dynamics. In this study, we quantified the temporal trends and spatial variations of spring phenology and snow cover across the Tibetan Plateau by calibrating and analyzing time series of the NOAA AVHRR-derived normalized difference vegetation index (NDVI) during 1983-2012. We also examined how snow cover dynamics affect the spatio-temporal pattern of spring alpine vegetation phenology over the plateau. Our results indicated that 52.21% of the plateau experienced a significant advancing trend in the beginning of vegetation growing season (BGS) and 34.30% exhibited a delaying trend. Accordingly, the snow cover duration days (SCD) and snow cover melt date (SCM) showed similar patterns with a decreasing trend in the west and an increasing trend in the southeast, but the start date of snow cover (SCS) showed an opposite pattern. Meanwhile, the spatial patterns of the BGS, SCD, SCS and SCM varied in accordance with the gradients of temperature, precipitation and topography across the plateau. The response relationship of spring phenology to snow cover dynamics varied within different climate, terrain and alpine plant community zones, and the spatio-temporal response patterns were primarily controlled by the long-term local heat-water conditions and topographic conditions. Moreover, temperature and precipitation played a profound impact on diverse responses of spring phenology to snow cover dynamics. Copyright © 2017 Elsevier B.V. All rights reserved.

SO/sub 2/ dose-response sensitivity classification data for crops and natural vegetation species

Energy Technology Data Exchange (ETDEWEB)

Irving, P.M.; Ballou, S.W.

1980-09-01

Over the past several years studies have been made on the interaction of sulfur dioxide (SO/sub 2/) and vegetation by performing field research and by developing analytical procedures for applying field observation data to energy impact assessments. As a result of this work, numerous reports have been prepared on crop-pollutant interactions, such as dose-response data; on the applications of such data to screening approaches for identifying crops at risk; and on models that predict crop yield reductions from point source emissions of SO/sub 2/. Data that were used for these studies, such as the crop-at-risk screening procedure, are presented in this report. Maps are also presented that show the national distribution of SO/sub 2/-sensitive crops and natural vegetation.

Spatio-temporal variation of vegetation coverage and its response to climate change in North China plain in the last 33 years

Science.gov (United States)

A, Duo; Zhao, Wenji; Qu, Xinyuan; Jing, Ran; Xiong, Kai

2016-12-01

Global climate change has led to significant vegetation changes in the past half century. North China Plain, the most important grain production base of china, is undergoing a process of prominent warming and drying. The vegetation coverage, which is used to monitor vegetation change, can respond to climate change (temperature and precipitation). In this study, GIMMS (Global Inventory Modelling and Mapping Studies)-NDVI (Normalized Difference Vegetation Index) data, MODIS (Moderate-resolution Imaging Spectroradiometer) - NDVI data and climate data, during 1981-2013, were used to investigate the spatial distribution and changes of vegetation. The relationship between climate and vegetation on different spatial (agriculture, forest and grassland) and temporal (yearly, decadal and monthly) scales were also analyzed in North China Plain. (1) It was found that temperature exhibiting a slight increase trend (0.20 °C/10a, P 0.05). The climate mutation period was during 1991-1994. (2) Vegetation coverage slight increase was observed in the 55% of total study area, with a change rate of 0.00039/10a. Human activities may not only accelerate the changes of the vegetation coverage, but also c effect to the rate of these changes. (3) Overall, the correlation between the vegetation coverage and climatic factor is higher in monthly scale than yearly scale. The correlation analysis between vegetation coverage and climate changes showed that annual vegetation coverage was better correlatend with precipitation in grassland biome; but it showed a better correlated with temperature i the agriculture biome and forest biome. In addition, the vegetation coverage had sensitive time-effect respond to precipitation. (4) The vegetation coverage showed the same increasing trend before and after the climatic variations, but the rate of increase slowed down. From the vegetation coverage point of view, the grassland ecological zone had an obvious response to the climatic variations, but the

The freezing and thawing of water in poultry meat and vegetables irradiated by electrons at doses of 0.1-4 kGy

International Nuclear Information System (INIS)

Dubini, B.; Montecchia, F.; Ponzi-Bossi, M.G.; Messina, G.

1993-01-01

Poultry meat and some vegetables, irradiated by 5 MeV electrons (0.1-4 kGy), were analysed by differential scanning calorimetry, from 24 h after irradiation. The temperature and enthalpy transitions of the water contained in the irradiated samples were measured and compared with those of unirradiated samples. The authors analysed 18 meat and 10 vegetable samples for each irradiation dose together with a similar number of unirradiated controls. The mean supercooling temperatures of water in the irradiated poultry meat samples and in some vegetables are significantly lower than those of controls. Moreover, the freezing enthalpies of the irradiated poultry breast are significantly lower than those of controls, while they are unchanged in the other cases. The mean ice melting temperatures and enthalpies are similar for all samples. The amount of the lowering of the water-ice transition depends on the nature of the sample and is highest in poultry breast and lowest in vegetables. (author)

Response of vegetation indices to changes in three measures of leaf water stress

Science.gov (United States)

Cohen, Warren B.

1991-01-01

The responses of vegetation indices to changes in water stress were evaluated in two separate laboratory experiments. In one experiment the normalized difference vegetation index (NDVI), the near-IR to red ratio (near-IR/red), the Infrared Index (II), and the Moisture Stress Index (MSI) were more highly correlated to leaf water potential in lodgepole pine branches than were the Leaf Water Content Index (LWCI), the mid-IR ratio (Mid-IR), or any of the single Thematic Mapper (TM) bands. In the other experiment, these six indices and the TM Tasseled Cap brightness, greenness, and wetness indices responded to changes in leaf relative water content (RWC) differently than they responded to changes in leaf water content (WC) of three plant species, and the responses were dependent on how experimental replicates were pooled. With no pooling, the LWCI was the most highly correlated index to both RWC and WC among replications, followed by the II, MSI, and wetness. Only the LWCI was highly correlated to RWC and WC when replications were pooled within species. With among species pooling the LWCI was the only index highly correlated with RWC, while the II, MSI, Mid-IR, and wetness were most highly correlated with WC.

Impacts of Vegetation Growth on Reach-scale Flood Hydraulics in a Sand-bed River and the Implications for Vegetation-morphology Coevolution

Science.gov (United States)

Box, S.; Wilcox, A. C.

2017-12-01

Vegetation alters flood hydraulics and geomorphic response, yet quantifying and predicting such responses across spatial and temporal scales remains challenging. Plant- and patch-scale studies consistently show that vegetation increases local hydraulic variability, yet reach-scale hydrodynamic models often assume vegetation has a spatially homogeneous effect on hydraulics. Using Nays2DH in iRIC (International River Interface Cooperative), we model the effect of spatially heterogeneous vegetation on a series of floods with varying antecedent vegetation conditions in a sand-bed river in western Arizona, taking advantage of over a decade of data on a system that experienced substantial geomorphic, hydrologic, and ecosystem changes. We show that pioneer woody seedlings (Tamarix, Populus, Salix) and cattail (Typha) increase local hydraulic variability, including velocity and bed shear stress, along individual cross sections, predominantly by decreasing velocity in zones of vegetation establishment and growth and increasing velocity in unvegetated areas, with analogous effects on shear stress. This was especially prominent in a study reach where vegetation growth contributed to thalweg incision relative to a vegetated bar. Evaluation of these results in the context of observed geomorphic response to floods elucidates mechanisms by which vegetation and channel morphology coevolve at a reach scale. By quantifying the influence of spatially heterogeneous vegetation on reach-scale hydraulics, we demonstrate that plant- and patch-scale research on vegetation hydraulics is applicable to ecogeomorphology at the reach scale.

When Winners Become Losers: Predicted Nonlinear Responses of Arctic Birds to Increasing Woody Vegetation.

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Sarah J Thompson

Full Text Available Climate change is facilitating rapid changes in the composition and distribution of vegetation at northern latitudes, raising questions about the responses of wildlife that rely on arctic ecosystems. One widely observed change occurring in arctic tundra ecosystems is an increasing dominance of deciduous shrub vegetation. Our goals were to examine the tolerance of arctic-nesting bird species to existing gradients of vegetation along the boreal forest-tundra ecotone, to predict the abundance of species across different heights and densities of shrubs, and to identify species that will be most or least responsive to ongoing expansion of shrubs in tundra ecosystems. We conducted 1,208 point counts on 12 study blocks from 2012-2014 in northwestern Alaska, using repeated surveys to account for imperfect detection of birds. We considered the importance of shrub height, density of low and tall shrubs (i.e. shrubs >0.5 m tall, percent of ground cover attributed to shrubs (including dwarf shrubs <0.5 m tall, and percent of herbaceous plant cover in predicting bird abundance. Among 17 species considered, only gray-cheeked thrush (Catharus minimus abundance was associated with the highest values of all shrub metrics in its top predictive model. All other species either declined in abundance in response to one or more shrub metrics or reached a threshold where further increases in shrubs did not contribute to greater abundance. In many instances the relationship between avian abundance and shrubs was nonlinear, with predicted abundance peaking at moderate values of the covariate, then declining at high values. In particular, a large number of species were responsive to increasing values of average shrub height with six species having highest abundance at near-zero values of shrub height and abundance of four other species decreasing once heights reached moderate values (≤ 33 cm. Our findings suggest that increases in shrub cover and density will negatively

Trend shifts in satellite-derived vegetation growth in Central Eurasia, 1982-2013.

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Xu, Hao-Jie; Wang, Xin-Ping; Yang, Tai-Bao

2017-02-01

Central Eurasian vegetation is critical for the regional ecological security and the global carbon cycle. However, climatic impacts on vegetation growth in Central Eurasia are uncertain. The reason for this uncertainty lies in the fact that the response of vegetation to climate change showed nonlinearity, seasonality and differences among plant functional types. Based on remotely sensed vegetation index and in-situ meteorological data for the years 1982-2013, in conjunction with the latest land cover type product, we analyzed how vegetation growth trend varied across different seasons and evaluated vegetation response to climate variables at regional, biome and pixel scales. We found a persistent increase in the growing season NDVI over Central Eurasia during 1982-1994, whereas this greening trend has stalled since the mid-1990s in response to increased water deficit. The stalled trend in the growing season NDVI was largely attributed by summer and autumn NDVI changes. Enhanced spring vegetation growth after 2002 was caused by rapid spring warming. The response of vegetation to climatic factors varied in different seasons. Precipitation was the main climate driver for the growing season and summer vegetation growth. Changes in temperature and precipitation during winter and spring controlled the spring vegetation growth. Autumn vegetation growth was mainly dependent on the vegetation growth in summer. We found diverse responses of different vegetation types to climate drivers in Central Eurasia. Forests were more responsive to temperature than to precipitation. Grassland and desert vegetation responded more strongly to precipitation than to temperature in summer but more strongly to temperature than to precipitation in spring. In addition, the growth of desert vegetation was more dependent on winter precipitation than that of grasslands. This study has important implications for improving the performance of terrestrial ecosystem models to predict future vegetation

Analyzing the vegetation response under different treatments after wildfires in NE Spain

Science.gov (United States)

León, Javier; Cerdà, Artemi; Badía, David; Echeverría, Maite; Martí, Clara

2014-05-01

Fire is a natural factor of landscape evolution in Mediterranean ecosystems. The socio-economic changes that occurred in the last decades have contributed to an increase in forest fires (Shakesby, 2011). There was found a change in the fire regimes in terms of frequency, size, seasonality, recurrence as well as fire intensity and severity (Keeley, 2009), which resulted in severe effects on soils, water and vegetation (Guénon et al., 2013). Fire affects soil properties directly by the heat impact (Aznar et al., 2013), and the ash cover (Cerdà and Doerr, 2008) and the reduction of the plant cover (Neary et al., 1999). The lack of vegetation and the heating promotes changes in the soil organic matter content (González-Pérez et al., 2004), on the structural stability (Mataix-Solera et al., 2011), on the hydrophobic response (Bodí et al., 2012), and on the infiltration capacity (Cerdà, 1998a). This is why the vegetation cover and the litter are key factors on soil erosion after forest fires (Prats et al., 2013). Besides, the ash plays an important paper in the soil protection after the forest fire and after the first storms and winds (León et al., 2013; Pereira et al., 2013). The objective of this experiment is to asses the vegetation response after a forest fire and the impact of vegetation recovery on soil erosion. The experiment consisted in a sampling of a linear transect of 10 m with samples each 2 m, under different slope position and aspect. To measure the soil erosion rates we used rainfall simulation experiments (León et al., 2013). The experiments were carried in Castejón (UTM 30T, X671106, Y4644584) in a forest burned in 2008, in the Zuera Mountains, both located in the north of Zaragoza province (NE Spain). The soils on limestone parent material are Rendzic Phaeozem (IUSS, 2007) and the texture of Ah horizons of soils developed on limestone is sandy-loam (Badía et al., 2013). The result shows fast and successful vegetation regeneration in the north

Simulating the vegetation response in western Europe to abrupt climate changes under glacial background conditions

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M.-N. Woillez

2013-03-01

Full Text Available The last glacial period has been punctuated by two types of abrupt climatic events, the Dansgaard–Oeschger (DO and Heinrich (HE events. These events, recorded in Greenland ice and in marine sediments, involved changes in the Atlantic Meridional Overturning Circulation (AMOC and led to major changes in the terrestrial biosphere. Here we use the dynamical global vegetation model ORCHIDEE to simulate the response of vegetation to abrupt changes in the AMOC strength. We force ORCHIDEE offline with outputs from the IPSL_CM4 general circulation model, in which the AMOC is forced to change by adding freshwater fluxes in the North Atlantic. We investigate the impact of a collapse and recovery of the AMOC, at different rates, and focus on Western Europe, where many pollen records are available for comparison. The impact of an AMOC collapse on the European mean temperatures and precipitations simulated by the GCM is relatively small but sufficient to drive an important regression of forests and expansion of grasses in ORCHIDEE, in qualitative agreement with pollen data for an HE event. On the contrary, a run with a rapid shift of the AMOC to a hyperactive state of 30 Sv, mimicking the warming phase of a DO event, does not exhibit a strong impact on the European vegetation compared to the glacial control state. For our model, simulating the impact of an HE event thus appears easier than simulating the abrupt transition towards the interstadial phase of a DO. For both a collapse or a recovery of the AMOC, the vegetation starts to respond to climatic changes immediately but reaches equilibrium about 200 yr after the climate equilibrates, suggesting a possible bias in the climatic reconstructions based on pollen records, which assume equilibrium between climate and vegetation. However, our study does not take into account vegetation feedbacks on the atmosphere.

Response function and optimum configuration of semiconductor backscattered-electron detectors for scanning electron microscopes

International Nuclear Information System (INIS)

Rau, E. I.; Orlikovskiy, N. A.; Ivanova, E. S.

2012-01-01

A new highly efficient design for semiconductor detectors of intermediate-energy electrons (1–50 keV) for application in scanning electron microscopes is proposed. Calculations of the response function of advanced detectors and control experiments show that the efficiency of the developed devices increases on average twofold, which is a significant positive factor in the operation of modern electron microscopes in the mode of low currents and at low primary electron energies.

Climate Change, Glacier Response, and Vegetation Dynamics in the Himalaya: Contributions Toward Future Earth Initiatives

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Joseph Shea

2017-08-01

Full Text Available Reviewed: Climate Change, Glacier Response, and Vegetation Dynamics in the Himalaya: Contributions Toward Future Earth Initiatives. Edited by R. B. Singh, Udo Schickhoff, and Suraj Mal. Cham, Switzerland: Springer, 2016. xvi + 399 pp. Hardcover: US$ 179.00, ISBN 978-3-319-28975-5. E-book: US$ 139.00, ISBN 978-3-319-28977-9.

Tanggung Jawab Hukum Penyelenggara Sistem Elektronik (Law Responsibility of the Electronic System Providers

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Abdul Salam

2011-09-01

Full Text Available Reviewing Edmon Makarim’s book which is about Law Responsibility of the Electronic System Providers, remind us that easiness and availability of electronic system in electronic transaction in private or public happen because the role of electronic system providers. Behind the important and central role, there is big responsibility for electronic system providers. But because of wide of definition of provision of electronic system and so many people who involve in electronic system providers, there is a question in our mind, how is the shape of responsibility of the electronic system providers if the electronic system which is held is broken and / or not in operation as it has to and bring loss to users. Which one from the electronic system providers should take the responsibility in law?

CORTICAL RESPONSES TO SALIENT NOCICEPTIVE AND NOT NOCICEPTIVE STIMULI IN VEGETATIVE AND MINIMAL CONSCIOUS STATE

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MARINA eDE TOMMASO

2015-01-01

Full Text Available Aims Questions regarding perception of pain in non-communicating patients and the management of pain continue to raise controversy both at a clinical and ethical level. The aim of this study was to examine the cortical response to salient multimodal visual, acoustic, somatosensory electric non nociceptive and nociceptive laser stimuli and their correlation with the clinical evaluation.Methods: Five Vegetative State (VS, 4 Minimally Conscious State (MCS patients and 11 age- and sex-matched controls were examined. Evoked responses were obtained by 64 scalp electrodes, while delivering auditory, visual, non-noxious electrical and noxious laser stimulation, which were randomly presented every 10 sec. Laser, somatosensory, auditory and visual evoked responses were identified as a negative-positive (N2-P2 vertex complex in the 500 msec post-stimulus time. We used Nociception Coma Scale-Revised (NCS-R and Coma Recovery Scale (CRS-R for clinical evaluation of pain perception and consciousness impairment.Results: The laser evoked potentials (LEPs were recognizable in all cases. Only one MCS patient showed a reliable cortical response to all the employed stimulus modalities. One VS patient did not present cortical responses to any other stimulus modality. In the remaining participants, auditory, visual and electrical related potentials were inconstantly present. Significant N2 and P2 latency prolongation occurred in both VS and MCS patients. The presence of a reliable cortical response to auditory, visual and electric stimuli was able to correctly classify VS and MCS patients with 90% accuracy. Laser P2 and N2 amplitudes were not correlated with the CRS-R and NCS-R scores, while auditory and electric related potentials amplitude were associated with the motor response to pain and consciousness recovery. Discussion: pain arousal may be a primary function also in vegetative state patients while the relevance of other stimulus modalities may indicate the

Vegetation response of a dry shrubland community to feral goat management on the island of Moloka‘i, Hawai‘i

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Jacobi, James D.; Stock, Jonathan

2017-12-14

The Hawaiian Islands are well known for their unique ecosystem assemblages that have a high proportion of endemic flora and fauna. However, since human colonization of this archipelago—starting with the arrival of Polynesian sailors approximately 1,200 years ago, and particularly following western contact in 1778—thousands of non-native species have been introduced to the Islands and many of these alien species have had severe impacts on the native ecosystems. Particularly damaging to these ecosystems are large mammals, including goats (Capra hircus), pigs (Sus scrofa), cattle (Bos taurus), deer (Axis axis and Odocoileus hemionus), and sheep (Ovis spp.), which are collectively referred to here as ungulates; they cause extensive damage to the native vegetation by their browsing, grazing, and trampling. Similar impacts have been documented elsewhere, including New Zealand and many other island ecosystems.Previous studies in Hawai‘i have utilized fenced exclosures to assess the impacts of feral or wild ungulates on vegetation and the recovery potential for the native plant communities by comparing plant community composition, structure, and cover inside the fenced area (without ungulates) over time to the vegetation condition outside of the protection of the fence. In some cases, the native vegetation recovered once the animals were removed. However, in other situations alien plants were more competitive and dominated the revegetation process after the impacts of ungulates had been reduced or eliminated.This report describes the response of a highly degraded lowland dry habitat plant community located on the south slope of east Moloka‘i, Hawai‘i, to reduction of browsing and grazing impacts caused by feral goats. For this study, vegetation response inside a fenced exclosure was compared to vegetation change in the area outside of the fence that was still accessible to goats. This study is part of the larger U.S. Geological Survey Ridge-to-Reef (USGS-R2R

Integrated Gis-remote sensing processing applied to vegetation ...

African Journals Online (AJOL)

A remotely sensed digital image of SPOT by its linear enhancement on a large memory, high speed, and digital electronic computer revealed from false colour composite that vegetation is expressed as red. Further processing of SPOT digital image for arithmetic banding of Normalized Differential Vegetation Index (NDVI) ...

The response of vegetation structure to active warming and precipitation reduction of the Sphagnum peatland

Science.gov (United States)

Łuców, Dominika; Basińska, Anna; Chojnicki, Bogdan; Gąbka, Maciej; Józefczyk, Damian; Juszczak, Radosław; Leśny, Jacek; Olejnik, Janusz; Reczuga, Monika; Samson, Mateusz; Silvennoinen, Hanna; Stróżecki, Marcin; Urbaniak, Marek; Zielińska, Małgorzata; Lamentowicz, Mariusz

2017-04-01

The recent climate change (e.g. increased temperature and decreased precipitation) is expected to affect biodiversity and vegetation structure of the European peatlands, as well as carbon fluxes. Our experimental study carried out in Western Poland, tests the hypothesis that the increased temperature, in particular in combination with rainfall reduction affects vegetation structure of the Sphagnum peatland, through changes in moss and vascular plants abundance. The innovative climate manipulation system was installed on the Rzecin peatland in 2014. The field site consists of four blocks: "drought" "warming and drought" "warming" and "control". The air and peat temperatures were increased in 2015 and 2016 by about 0.2 oC and 1.0 oC, respectively, using infrared radiators. Precipitation was reduced by automatic curtain operated only during the nights by about 37 % in both years. Data resulting from the analyses of digital pictures as well as Point Intercept method were used to identify changes in vegetation structure as a response to warming and drought. We observed increase in abundance of vascular plant and decrease in abundance of mosses during the very dry 2015 vegetation season. It appeared that Carex spp. (C. limosa and C. rostrata) abundance responded positively to warming, while Sphagnum spp. (S. angustifolium and S. teres) responded negatively. The "warming" block was characterized by an increase in abundance of Carex spp. by 8.3 % to 16.7 % and decreased abundance of Sphagnum spp. from 25 % to 19.4 %, whereas in the block of "warming and drought" 11.4 % to by 18.3 and 38 % to 26.9 %, respectively in the August 2015. However, we observed decrease in Sphagnum spp. abundance in the treatment with rainfall reduction in wetter 2016, and their increase in the control. Our results show how considerable changes in vegetation structure can be expected under the stress of warming and modified rainfall conditions, even after a short-term manipulation. However, it is

Characterizing the response of a scintillator-based detector to single electrons

International Nuclear Information System (INIS)

Sang, Xiahan; LeBeau, James M.

2016-01-01

Here we report the response of a high angle annular dark field scintillator-based detector to single electrons. We demonstrate that care must be taken when determining the single electron intensity as significant discrepancies can occur when quantifying STEM images with different methods. To account for the detector response, we first image the detector using very low beam currents (∼8 fA), and subsequently model the interval between consecutive single electrons events. We find that single electrons striking the detector present a wide distribution of intensities, which we show is not described by a simple function. Further, we present a method to accurately account for the electrons within the incident probe when conducting quantitative imaging. The role detector settings play on determining the single electron intensity is also explored. Finally, we extend our analysis to describe the response of the detector to multiple electron events within the dwell interval of each pixel. - Highlights: • We show that the statistical description of single electron response of scintillator based detectors can be measured using a combination of small beam currents and short dwell times. • The average intensity from the probability distribution function can be used to normalize STEM images regardless of beam current and contrast settings. • We obtain consistent QSTEM normalization results from the single electron method and the conventional detector scan method.

River ecosystem response to prescribed vegetation burning on Blanket Peatland.

Science.gov (United States)

Brown, Lee E; Johnston, Kerrylyn; Palmer, Sheila M; Aspray, Katie L; Holden, Joseph

2013-01-01

Catchment-scale land-use change is recognised as a major threat to aquatic biodiversity and ecosystem functioning globally. In the UK uplands rotational vegetation burning is practised widely to boost production of recreational game birds, and while some recent studies have suggested burning can alter river water quality there has been minimal attention paid to effects on aquatic biota. We studied ten rivers across the north of England between March 2010 and October 2011, five of which drained burned catchments and five from unburned catchments. There were significant effects of burning, season and their interaction on river macroinvertebrate communities, with rivers draining burned catchments having significantly lower taxonomic richness and Simpson's diversity. ANOSIM revealed a significant effect of burning on macroinvertebrate community composition, with typically reduced Ephemeroptera abundance and diversity and greater abundance of Chironomidae and Nemouridae. Grazer and collector-gatherer feeding groups were also significantly less abundant in rivers draining burned catchments. These biotic changes were associated with lower pH and higher Si, Mn, Fe and Al in burned systems. Vegetation burning on peatland therefore has effects beyond the terrestrial part of the system where the management intervention is being practiced. Similar responses of river macroinvertebrate communities have been observed in peatlands disturbed by forestry activity across northern Europe. Finally we found river ecosystem changes similar to those observed in studies of wild and prescribed forest fires across North America and South Africa, illustrating some potentially generic effects of fire on aquatic ecosystems.

Short-term responses of wetland vegetation after liming of an Adirondack watershed

Energy Technology Data Exchange (ETDEWEB)

Mackun, I.R.; Leopold, D.J.; Raynal, D.J. (State Univ. of New York, Syracuse, NY (United States))

1994-08-01

Watershed liming has been suggested as a long-term mitigation strategy for lake acidity, particularly in areas subject to high levels of acidic deposition. However, virtually no information has been available on the impacts of liming on wetland vegetation. In 1989, 1100 Mg of limestone (83.5% CaCO[sub 3]) were aerially applied to 48% (100 ha) of the Woods Lake watershed in the west-central Adirondack region of New York as part of the first comprehensive watershed liming study in North America. We inventoried wetland vegetation in 1.0-m[sup 2] plots before liming and during the subsequent 2 yr. Within this period liming influenced the cover, frequency, or importance values of only 6 of 64 wetland taxa. The cover of Sphagnum spp. and of the cespitose sedge Carex interior decreased in control relative to limed plots, and cover of the rhizomatous sedge Cladium mariscoides increased nearly threefold in limed areas. These two sedges, which are relatively tall, are characteristic of more calcareous habitats. Cover of the grass Muhlenbergia uniflora, cover and importance were adversely affected or inhibited by lime. It is unclear whether liming directly inhibited the growth of these three small-statured species, or whether the adverse effects of lime were mediated through shifts in competitive interactions with other species. The limited responses that we observed to liming, along with changes that occurred in control plots over the study period, may indicate that in the short term watershed liming was no more of a perturbation than the environmental factors responsible for natural annual variation in wetland communities.

Efficacy and External Validity of Electronic and Mobile Phone-Based Interventions Promoting Vegetable Intake in Young Adults: Systematic Review and Meta-Analysis.

Science.gov (United States)

Nour, Monica; Chen, Juliana; Allman-Farinelli, Margaret

2016-04-08

Young adults (18-35 years) remain among the lowest vegetable consumers in many western countries. The digital era offers opportunities to engage this age group in interventions in new and appealing ways. This systematic review evaluated the efficacy and external validity of electronic (eHealth) and mobile phone (mHealth) -based interventions that promote vegetable intake in young adults. We searched several electronic databases for studies published between 1990 and 2015, and 2 independent authors reviewed the quality and risk of bias of the eligible papers and extracted data for analyses. The primary outcome of interest was the change in vegetable intake postintervention. Where possible, we calculated effect sizes (Cohen d and 95% CIs) for comparison. A random effects model was applied to the data for meta-analysis. Reach and representativeness of participants, intervention implementation, and program maintenance were assessed to establish external validity. Published validation studies were consulted to determine the validity of tools used to measure intake. We applied the Grading of Recommendations Assessment, Development and Evaluation (GRADE) system to evaluate the overall quality of the body of evidence. Of the 14 studies that met the selection criteria, we included 12 in the meta-analysis. In the meta-analysis, 7 studies found positive effects postintervention for fruit and vegetable intake, Cohen d 0.14-0.56 (pooled effect size 0.22, 95% CI 0.11-0.33, I(2)=68.5%, P=.002), and 4 recorded positive effects on vegetable intake alone, Cohen d 0.11-0.40 (pooled effect size 0.15, 95% CI 0.04-0.28, I(2)=31.4%, P=.2). These findings should be interpreted with caution due to variability in intervention design and outcome measures. With the majority of outcomes documented as a change in combined fruit and vegetable intake, it was difficult to determine intervention effects on vegetable consumption specifically. Measurement of intake was most commonly by self

Rapid continental-scale vegetation response to the Younger Dryas Cool Episode

Science.gov (United States)

Peros, M.; Gajewski, K.; Viau, A.

2006-12-01

The Younger Dryas Cool Episode had rapid and widespread effects on flora and fauna throughout the Americas. Fossil pollen records document how plant communities responded to this event, although such data are generally only representative of changes at local- to regional-scales. We use a new approach to provide insight into vegetation responses to the Younger Dryas at a continental-scale, by focusing on data extracted for a single taxon (Populus poplar, cottonwood, aspen) from pollen diagrams throughout North America. We show that Populus underwent a rapid and continent-wide decline as the climate rapidly cooled and dried. At the termination of the Younger Dryas, Populus underwent another widespread decline, this time in response to competition from boreal and temperate taxa as the climate abruptly warmed. Late glacial-early Holocene pollen assemblages with high quantities of Populus pollen often lack modern analogues and thus confound quantitative paleoclimatic reconstructions; our results provide a context to interpret these assemblages. Furthermore, while Populus may continue to expand in the future in response to human disturbance and increasing temperatures, its sensitivity to competition may eventually put it at risk as global warming accelerates.

Consumer attitudes towards vegetable attributes: potential buyers of pesticide-free vegetables in Accra and Kumasi, Ghana.

Science.gov (United States)

Probst, Lorenz; Aigelsperger, Lisa; Hauser, Michael

2010-01-01

Considering the inappropriate use of synthetic pesticides on vegetables in West Africa, the rationale behind this research was to assess the extent to which consumers can function as demanders of risk reduced vegetables and hence act as innovators towards vegetable safety. Using the cases of Kumasi and Accra in Ghana, the study examined possible consumer responses to product certification that communicates freedom from pesticides (e.g., organic certification). Generally, search attributes such as the fresh and healthy appearance of a vegetable were found to be central to consumer choice. While consumers stress the importance of health value, they are mostly unaware of agro-chemical risks related to vegetable consumption.

Characteristics of Response of Piezoelectric Actuators in Electron Flux Excitation

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Philip C. Hadinata

2003-11-01

Full Text Available In this paper the working parameters of non-contact strain control for piezoelectric ceramics are evaluated. The piezoelectric material functions as an actuator that transforms electrical into mechanical energy, and the electrical input is carried out by electron flux on the positive surface. The sample is exposed to some quasi-static inputs, and its responses are recorded using strain gages. The data shows faster and more stable response in the positive regime, but significantly slower response with drift in the negative regime. An electron collector is introduced on the positive surface to enhance the response in the negative regime. Theoretical analyses of energy transfer and electron movements is discussed, and a string of working conditions for controlling the surface strain of piezoelectric material are given as conclusions.

Contrasting germination responses to vegetative canopies experienced in pre- vs. post-dispersal environments

Science.gov (United States)

Leverett, Lindsay D.; Auge, Gabriela A.; Bali, Aman; Donohue, Kathleen

2016-01-01

Background Seeds adjust their germination based on conditions experienced before and after dispersal. Post-dispersal cues are expected to be more accurate predictors of offspring environments, and thus offspring success, than pre-dispersal cues. Therefore, germination responses to conditions experienced during seed maturation may be expected to be superseded by responses to conditions experienced during seed imbibition. In taxa of disturbed habitats, neighbours frequently reduce the performance of germinants. This leads to the hypotheses that a vegetative canopy will reduce germination in such taxa, and that a vegetative canopy experienced during seed imbibition will over-ride germination responses to a canopy experienced during seed maturation, since it is a more proximal cue of immediate competition. These hypotheses were tested here in Arabidopsis thaliana. Methods Seeds were matured under a simulated canopy (green filter) or white light. Fresh (dormant) seeds were imbibed in the dark, white light or canopy at two temperatures (10 or 22 °C), and germination proportions were recorded. Germination was also recorded in after-ripened (less dormant) seeds that were induced into secondary dormancy and imbibed in the dark at each temperature, either with or without brief exposure to red and far-red light. Key Results Unexpectedly, a maturation canopy expanded the conditions that elicited germination, even as seeds lost and regained dormancy. In contrast, an imbibition canopy impeded or had no effect on germination. Maturation under a canopy did not modify germination responses to red and far-red light. Seed maturation under a canopy masked genetic variation in germination. Conclusions The results challenge the hypothesis that offspring will respond more strongly to their own environment than to that of their parents. The observed relaxation of germination requirements caused by a maturation canopy could be maladaptive for offspring by disrupting germination responses

Yield Responses of Black Spruce to Forest Vegetation Management Treatments: Initial Responses and Rotational Projections

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Peter F. Newton

2012-01-01

Full Text Available The objectives of this study were to (1 quantitatively summarize the early yield responses of black spruce (Picea mariana (Mill. B.S.P. to forest vegetation management (FVM treatments through a meta-analytical review of the scientific literature, and (2 given (1, estimate the rotational consequences of these responses through model simulation. Based on a fixed-effects meta-analytic approach using 44 treated-control yield pairs derived from 12 experiments situated throughout the Great Lakes—St. Lawrence and Canadian Boreal Forest Regions, the resultant mean effect size (response ratio and associated 95% confidence interval for basal diameter, total height, stem volume, and survival responses, were respectively: 54.7% (95% confidence limits (lower/upper: 34.8/77.6, 27.3% (15.7/40.0, 198.7% (70.3/423.5, and 2.9% (−5.5/11.8. The results also indicated that early and repeated treatments will yield the largest gains in terms of mean tree size and survival. Rotational simulations indicated that FVM treatments resulted in gains in stand-level operability (e.g., reductions of 9 and 5 yr for plantations established on poor-medium and good-excellent site qualities, resp.. The challenge of maintaining coniferous forest cover on recently disturbed sites, attaining statutory-defined free-to-grow status, and ensuring long-term productivity, suggest that FVM will continue to be an essential silvicultural treatment option when managing black spruce plantations.

Changes in Soil Carbon Stocks and Fluxes in Response to Altered Above- and Belowground Vegetation Inputs

Science.gov (United States)

Marañón-Jiménez, S.; Schuetze, C.; Cuntz, M.; García-Quirós, I.; Dienstbach, L.; Schrumpf, M.; Rebmann, C.

2016-12-01

The stimulation of vegetation productivity in response to rising atmospheric CO2 concentrations can potentially compensate climate change feedbacks. However, this will depend on the allocation of C resources of vegetation into biomass production versus root exudates and on the feedbacks with soil microorganisms. These dynamic adjustments of vegetation will result on changes in above- and belowground productivity and on the amount of C exported to root exudates. Consequent alteration of litter and rhizosphere detritus inputs to the soil and their interaction on controlling soil C sequestration capacity has been, however, rarely assessed. We hypothesize that above- and belowground vegetation exert a synergistic control of soil CO2 emissions, and that the activation of soil organic matter mineralization by the addition of labile organic substrates (i.e.: the priming effect) is altered by changes in the amount and in the quality of the carbon inputs. In order to elucidate these questions, different levels of litter addition were implemented on trenched (root exclusion) and non-trenched plots (with roots) in a temperate deciduous forest. Changes in the sensitivity of soil respiration to temperature and moisture were detected by measuring CO2 fluxes continuously at high temporal resolution with automatic chambers, whereas the spatial and seasonal variability was determined using portable chambers. Annual changes in soil carbon and nitrogen stocks provide additional information on the soil carbon sequestration in response to above- and belowground inputs. Both roots and litter inputs significantly enhanced soil CO2 effluxes soon after the implementation of the experiment. We detected synergistic effects between roots and litter inputs on soil CO2 emissions: When roots were present, carbon mineralized in response to litter addition was much higher than the total amount of carbon added in litter (ca. 170 g C m-2 y-1). Preliminary results of this study suggest that labile

Responses and mechanisms of positive electron affinity molecules in the N2 mode of the thermionic ionization detector and the electron-capture detector

International Nuclear Information System (INIS)

Jones, C.S.

1989-01-01

Very little knowledge has been acquired in the past on the mechanistic pathway by which molecules respond in the N 2 mode of the thermionic ionization detector. An attempt is made here to elucidate the response mechanism of the detector. The basic response mechanisms are known for the electron capture detector, and an attempt is made to identify the certain mechanism by which selected molecules respond. The resonance electron capture rate constant has been believed to be temperature independent, and investigations of the temperature dependence of electron capture responses are presented. Mechanisms for the N 2 mode of the thermionic ionization detector have been proposed by examining the detector response to positive electron affinity molecules and by measurement of the ions produced by the detector. Electron capture mechanisms for selected molecules have been proposed by examining their temperature dependent responses in the electron capture detector and negative ion mass spectra of the samples. In studies of the resonance electron capture rate constant, the relative responses of selected positive electron affinity molecules and their temperature dependent responses were investigated. Positive electron affinity did not guarantee large responses in the N 2 mode thermionic ionization detector. High mass ions were measured following ionization of samples in the detector. Responses in the electron capture detector varied with temperature and electron affinity

Response of Vegetation to Climate Change in the Drylands of East Asia

International Nuclear Information System (INIS)

Dai, L; Wang, K; Wang, R L; Zhang, L

2014-01-01

Over the past 25 years, global climate and environmental changes have caused an unprecedented rate of vegetation change, as exemplified in the drylands of East Asia. In this study, we investigated the spatio-temporal changes of vegetation in this region and analysed their relationship with climate data. Our results show that vegetation productivity significantly increased from 1982 to 2006. This increasing trend was observed for most of the region, particularly for northwest Mongolia and central Inner Mongolia. Grasslands, croplands, forests, and shrublands, all exhibited this trend. The annual growth rate of the grasslands determined using the Normalized Difference Vegetation Index (NDVI) was the largest observed change; reaching 0.07% p.a, followed by shrublands (0.06%), croplands (0.03%), and forests (0.02%). In the different geographic regions, the roles of temperature and precipitation on vegetation growth were shown to be different. Temperature was the dominant factor for the observed NDVI increase in northwest Mongolia and the centre of Inner Mongolia. The combined influences of temperature and precipitation changes have resulted in the promotion of vegetation growth, as seen in eastern GanSu. Temperature change is the primary factor for initiating vegetation growth in spring and autumn because warmer temperatures increase the length of the growing season, and are thus evaluated as an increased NDVI value. Increased precipitation has been shown to play a positive role on vegetation growth during summer

Terrestrial Water Storage and Vegetation Resilience to Drought

Science.gov (United States)

Meyer, V.; Reager, J. T., II; Konings, A. G.

2017-12-01

The expected increased occurrences of hydrologic extreme events such as droughts in the coming decades motivates studies to better understand and predict the response of vegetation to such extreme conditions. Previous studies have addressed vegetation resilience to drought, defined as its ability to recover from a perturbation (Hirota et al., 2011; Vicente-Serrano et al., 2012), but appear to only focus on precipitation and a couple of vegetation indices, hence lacking a key element: terrestrial water storage (TWS). In this study, we combine and compare multiple remotely-sensed hydro-ecological datasets providing information on climatic and hydrological conditions (Tropical Rainfall Measuring Mission (TRMM), Gravity Recovery and Climate Experiment (GRACE)) and indices characterizing the state of the vegetation (vegetation water content using Vegetation Optical Depth (VOD) from SMAP (Soil Moisture Active and Passive), Gross Primary Production (GPP) from FluxCom and Specific Fluorescence Intensity (SFI, from GOSat)) to assess the ability of vegetation to face and recover from droughts across the globe. Our results suggest that GRACE hydrological data bridge the knowledge gap between precipitation deficit and vegetation response. All products are aggregated at a 0.5º spatial resolution and a monthly temporal resolution to match the GRACE Mascon product. Despite these coarse spatiotemporal resolutions, we find that the relationship between existing remotely-sensed eco-hydrologic data varies spatially, both in terms of strength of relationship and time lag, showing the response time of vegetation characteristics to hydrological changes and highlighting the role of water storage. A special attention is given to the Amazon river basin, where two well documented droughts occurred in 2005 and 2010, and where a more recent drought occurred in 2015/2016. References : Hirota, Marina, et al. "Global resilience of tropical forest and savanna to critical transitions." Science

Vegetation Response to Upper Pliocene Glacial/Interglacial Cyclicity in the Central Mediterranean

Science.gov (United States)

Combourieu-Nebout, Nathalie

1993-09-01

New detailed pollen analysis of the lower part of the Upper Pliocene Semaforo section (Crotone, Italy) documents cyclic behavior of vegetation at the beginning of the Northern Hemisphere glaciations. The competition between four vegetation units (subtropical humid forest, deciduous temperate forest, altitudinal coniferous forest, and open xeric assemblage) probably reflects modifications of vegetation belts at this montane site. Several increases in herbaceous open vegetation regularly alternate with subtropical humid forest, which expresses rapid climatic oscillations. The complete temporal succession—deciduous forest (rich in Quercus), followed by subtropical humid forest (Taxodiaceae and Cathaya), then altitudinal coniferous forest ( Tsuga, Cedrus, Abies, and Picea), and finally herbaceous open vegetation (Graminae, Compositae, and Artemisia )—displays the climatic evolution from warm and humid interglaciation to cold and dry glaciation. It also suggests an independent variation of temperature and humidity, the two main climatic parameters. The vegetation history of southern Calabria recorded in the Semaforo section have been correlated with the ∂ 18O signal established in the Atlantic Ocean.

Intake of fruit and vegetables and risk of bladder cancer: a dose-response meta-analysis of observational studies.

Science.gov (United States)

Yao, Baodong; Yan, Yujie; Ye, Xianwu; Fang, Hong; Xu, Huilin; Liu, Yinan; Li, Sheran; Zhao, Yanping

2014-12-01

Observational studies suggest an association between fruit and vegetables intake and risk of bladder cancer, but the results are controversial. We therefore summarized the evidence from observational studies in categorical, linear, and nonlinear, dose-response meta-analysis. Pertinent studies were identified by searching EMBASE and PubMed from their inception to August 2013. Thirty-one observational studies involving 12,610 cases and 1,121,649 participants were included. The combined rate ratio (RR, 95 % CI) of bladder cancer for the highest versus lowest intake was 0.83 (0.69-0.99) for total fruit and vegetables, 0.81 (0.70-0.93) for total vegetables, 0.77 (0.69-0.87) for total fruit, 0.84 (0.77-0.91) for cruciferous vegetables, 0.79 (0.68-0.91) for citrus fruits, and 0.74 (0.66-0.84) for yellow-orange vegetables. Subgroup analysis showed study design and gender as possible sources of heterogeneity. A nonlinear relationship was found of citrus fruits intake with risk of bladder cancer (P for nonlinearity = 0.018), and the RRs (95 % CI) of bladder cancer were 0.87 (0.78-0.96), 0.80 (0.67-0.94), 0.79 (0.66-0.94), 0.79 (0.65-0.96), and 0.79 (0.64-0.99) for 30, 60, 90, 120, and 150 g/day. A nonlinear relationship was also found of yellow-orange vegetable intake with risk of bladder cancer risk (P for nonlinearity = 0.033). Some evidence of publication bias was observed for fruit, citrus fruits, and yellow-orange vegetables. This meta-analysis supports the hypothesis that intakes of fruit and vegetables may reduce the risk of bladder cancer. Future well-designed studies are required to confirm this finding.

Vegetation morphologic and aerodynamic characteristics reduce aeolian erosion.

Science.gov (United States)

Miri, Abbas; Dragovich, Deirdre; Dong, Zhibao

2017-10-09

Vegetation cover is crucial to controlling aeolian erosion but highly efficient vegetation is critical. How this efficiency is influenced by vegetation response to airflow is not clear. Here we evaluate the responses of Cosmos bipinnatus and Ligustrum lucidum Ait to a range of wind speeds in a wind tunnel. For both species, we calculate shelter effect and sand flux. We show that plant effectiveness in reducing wind speed and sediment transport is linked to their aerodynamic response to airflow which results from their morphology. We demonstrate that in low-density cover the flow-response and resistance of individuals is most critical in the optimal effectiveness of a canopy. Our wind tunnel experiment suggests that vegetation morphology and structure must be priority parameters in facilitating aeolian erosion control.

Tracing the transition of a macro electron shuttle into nonlinear response

Energy Technology Data Exchange (ETDEWEB)

Kim, Chulki [Sensor System Research Center, Korea Institute of Science and Technology, Seoul 136791 (Korea, Republic of); Prada, Marta [I. Institut für Theoretische Physik, Universität Hamburg, Jungiusstr. 9, Hamburg 20355 (Germany); Qin, Hua [Key Laboratory of Nanodevices, Suzhou Institute of Nano-Tech and Nano-Bionics, Chinese Academy of Sciences, 398 Ruoshui Road, Industrial Park, Suzhou City, Jiangsu 215123 (China); Kim, Hyun-Seok [Division of Electronics and Electrical Engineering, Dongguk University-Seoul, 100715 Seoul (Korea, Republic of); Blick, Robert H., E-mail: rblick@physnet.uni-hamburg.de [Department of Physics, University of Wisconsin-Madison, 1150 University Avenue, Madison, Wisconsin-53706 (United States); Center for Hybrid Nanostructures, Universität Hamburg, Jungiusstr. 11c, Hamburg 20355 (Germany); Department of Electrical and Computer Engineering, University of Wisconsin-Madison, 1415 Engineering Dr. Madison, Wisconsin-53706 (United States)

2015-02-09

We present a study on a macroscopic electron shuttle in the transition from linear to nonlinear response. The shuttle consists of a classical mechanical pendulum situated between two capacitor plates. The metallic pendulum enables mechanical transfer of electrons between the plates, hence allowing to directly trace electron shuttling in the time domain. By applying a high voltage to the plates, we drive the system into a controlled nonlinear response, where we observe period doubling.

Dynamic Response of Satellite-Derived Vegetation Growth to Climate Change in the Three North Shelter Forest Region in China

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Bin He

2015-08-01

Full Text Available Since the late 1970s, the Chinese government has initiated ecological restoration programs in the Three North Shelter Forest System Project (TNSFSP area. Whether accelerated climate change will help or hinder these efforts is still poorly understood. Using the updated and extended AVHRR NDVI3g dataset from 1982 to 2011 and corresponding climatic data, we investigated vegetation variations in response to climate change. The results showed that the overall state of vegetation in the study region has improved over the past three decades. Vegetation cover significantly decreased in 23.1% and significantly increased in 21.8% of the study area. An increase in all three main vegetation types (forest, grassland, and cropland was observed, but the trend was only statistically significant in cropland. In addition, bare and sparsely vegetated areas, mainly located in the western part of the study area, have significantly expanded since the early 2000s. A moisture condition analysis indicated that the study area experienced significant climate variations, with warm-wet conditions in the western region and warm-dry conditions in the eastern region. Correlation analysis showed that variations in the Normalized Difference Vegetation Index (NDVI were positively correlated with precipitation and negatively correlated with temperature. Ultimately, climate change influenced vegetation growth by controlling the availability of soil moisture. Further investigation suggested that the positive impacts of precipitation on NDVI have weakened in the study region, whereas the negative impacts from temperature have been enhanced in the eastern study area. However, over recent years, the negative temperature impacts have been converted to positive impacts in the western region. Considering the variations in the relationship between NDVI and climatic variables, the warm–dry climate in the eastern region is likely harmful to vegetation growth, whereas the warm�

Efficacy and External Validity of Electronic and Mobile Phone-Based Interventions Promoting Vegetable Intake in Young Adults: A Systematic Review Protocol.

Science.gov (United States)

Nour, Monica Marina; Chen, Juliana; Allman-Farinelli, Margaret

2015-07-28

Despite social marketing campaigns and behavior change interventions, young adults remain among the lowest consumers of vegetables. The digital era offers potential new avenues for both social marketing and individually tailored programs, through texting, web, and mobile applications. The effectiveness and generalizability of such programs have not been well documented. The aim of this systematic review is to evaluate the efficacy and external validity of social marketing, electronic, and mobile phone-based (mHealth) interventions aimed at increasing vegetable intake in young adults. The Preferred Reporting Items for Systematic Reviews and Meta-Analysis (PRISMA) protocol will be used to conduct this systematic review. The search strategy will be executed across eleven electronic databases using combinations of the following search terms: "online intervention", "computer-assisted therapy", "internet", "website", "cell phones", "cyber", "telemedicine", "email", "social marketing", "social media", "mass media", "young adult", and "fruit and vegetables". The reference lists of included studies will also be searched for additional citations. Titles and abstracts will be screened against inclusion criteria and full texts of potentially eligible papers will be assessed by two independent reviewers. Data from eligible papers will be extracted. Quality and risk of bias will be assessed using the Effective Public Health Practice Project (EPHPP) Quality Assessment Tool for Quantitative Studies and The Cochrane Collaboration Risk of Bias assessment tool respectively. The external validity of the studies will be determined based on components such as reach, adoption, and representativeness of participants; intervention implementation and adaption; and program maintenance and institutionalization. Results will be reported quantitatively and qualitatively. Our research is in progress. A draft of the systematic review is currently being produced for publication by the end of 2015

Remote sensing analysis of riparian vegetation response to desert marsh restoration in the Mexican Highlands

Science.gov (United States)

Norman, Laura M.; Villarreal, Miguel; Pulliam, H. Ronald; Minckley, Robert L.; Gass, Leila; Tolle, Cindy; Coe, Michelle

2014-01-01

Desert marshes, or cienegas, are extremely biodiverse habitats imperiled by anthropogenic demands for water and changing climates. Given their widespread loss and increased recognition, remarkably little is known about restoration techniques. In this study, we examine the effects of gabions (wire baskets filled with rocks used as dams) on vegetation in the Cienega San Bernardino, in the Arizona, Sonora portion of the US-Mexico border, using a remote-sensing analysis coupled with field data. The Normalized Difference Vegetation Index (NDVI), used here as a proxy for plant biomass, is compared at gabion and control sites over a 27-year period during the driest months (May/June). Over this period, green-up occurred at most sites where there were gabions and at a few of the control sites where gabions had not been constructed. When we statistically controlled for differences among sites in source area, stream order, elevation, and interannual winter rainfall, as well as comparisons of before and after the initiation of gabion construction, vegetation increased around gabions yet did not change (or decreased) where there were no gabions. We found that NDVI does not vary with precipitation inputs prior to construction of gabions but demonstrates a strong response to precipitation after the gabions are built. Field data describing plant cover, species richness, and species composition document increases from 2000 to 2012 and corroborate reestablished biomass at gabions. Our findings validate that gabions can be used to restore riparian vegetation and potentially ameliorate drought conditions in a desert cienega.

The Global Index of Vegetation-Plot Databases 1 (GIVD): a new resource for vegetation science

NARCIS (Netherlands)

Dengler, J.; Jansen, F.; Glockler, F.; Schaminee, J.H.J.

2011-01-01

Question: How many vegetation plot observations (relevés) are available in electronic databases, how are they geographically distributed, what are their properties and how might they be discovered and located for research and application? Location: Global. Methods: We compiled the Global Index of

Response characteristics of vegetation and soil environment to permafrost degradation in the upstream regions of the Shule River Basin

International Nuclear Information System (INIS)

Chen Shengyun; Liu Wenjie; Qin Xiang; Liu Yushuo; Ren Jiawen; Qin Dahe; Zhang Tongzuo; Hu Fengzu; Chen Kelong

2012-01-01

Permafrost degradation exhibits striking and profound influences on the alpine ecosystem, and response characteristics of vegetation and soil environment to such degradation inevitably differ during the entire degraded periods. However, up to now, the related research is lacking in the Qinghai–Tibetan Plateau (QTP). For this reason, twenty ecological plots in the different types of permafrost zones were selected in the upstream regions of the Shule River Basin on the northeastern margin of the QTP. Vegetation characteristics (species diversity, community coverage and biomass etc) and topsoil environment (temperature (ST), water content (SW), mechanical composition (SMC), culturable microorganism (SCM), organic carbon (SOC) and total nitrogen (TN) contents and so on), as well as active layer thickness (ALT) were investigated in late July 2009 and 2010. A spatial–temporal shifts method (the spatial pattern that is represented by different types of permafrost shifting to the temporal series that stands for different stages of permafrost degradation) has been used to discuss response characteristics of vegetation and topsoil environment throughout the entire permafrost degradation. The results showed that (1) ST of 0–40 cm depth and ALT gradually increased from highly stable and stable permafrost (H-SP) to unstable permafrost (UP). SW increased initially and then decreased, and SOC content and the quantities of SCM at a depth of 0–20 cm first decreased and then increased, whereas TN content and SMC showed obscure trends throughout the stages of permafrost degradation with a stability decline from H-SP to extremely unstable permafrost (EUP); (2) further, species diversity, community coverage and biomass first increased and then decreased in the stages from H-SP to EUP; (3) in the alpine meadow ecosystem, SOC and TN contents increased initially and then decreased, soil sandy fractions gradually increased with stages of permafrost degradation from substable (SSP

Ranking TEM cameras by their response to electron shot noise

International Nuclear Information System (INIS)

Grob, Patricia; Bean, Derek; Typke, Dieter; Li, Xueming; Nogales, Eva; Glaeser, Robert M.

2013-01-01

We demonstrate two ways in which the Fourier transforms of images that consist solely of randomly distributed electrons (shot noise) can be used to compare the relative performance of different electronic cameras. The principle is to determine how closely the Fourier transform of a given image does, or does not, approach that of an image produced by an ideal camera, i.e. one for which single-electron events are modeled as Kronecker delta functions located at the same pixels where the electrons were incident on the camera. Experimentally, the average width of the single-electron response is characterized by fitting a single Lorentzian function to the azimuthally averaged amplitude of the Fourier transform. The reciprocal of the spatial frequency at which the Lorentzian function falls to a value of 0.5 provides an estimate of the number of pixels at which the corresponding line-spread function falls to a value of 1/e. In addition, the excess noise due to stochastic variations in the magnitude of the response of the camera (for single-electron events) is characterized by the amount to which the appropriately normalized power spectrum does, or does not, exceed the total number of electrons in the image. These simple measurements provide an easy way to evaluate the relative performance of different cameras. To illustrate this point we present data for three different types of scintillator–coupled camera plus a silicon-pixel (direct detection) camera. - Highlights: ► Fourier amplitude spectra of noise are well fitted by a single Lorentzian. ► This measures how closely, or not, the response approaches the single-pixel ideal. ► Noise in the Fourier amplitudes is (1−π/4) times the shot noise power spectrum. ► Finite variance in the single-electron responses adds to the output noise. ► This excess noise may be equal to or greater than shot noise itself

Evaluation of identification methods of irradiated spices and dehydrated vegetables in Brazil

International Nuclear Information System (INIS)

Bernardes, D.M.L.; Del Mastro, N.L.

1998-01-01

Complete text of publication follows. This paper deals with the use of analytical methods to determine whether imported or for export Brazilian spices and dehydrated vegetables were irradiated. Viscosimetry, thermoluminescence (TL) and electron spin resonance (ESR) were used for the identification of some irradiated products: black pepper, white pepper, cinnamon, nutmeg, garlic, cumin, oregano, celery, paprika and coriander. Viscosimetry was performed in suspensions of irradiated spices and dehydrated vegetables which had been gellified by heat. Thermoluminescence (TL) is based on the transference of electrons to an excited state by radiation with emission of light when the electrons are thermally stimulated. The thermoluminescent signal of spices can be explained by the presence of mineral grains adhering on the surface of the samples. Free radicals produced by irradiation of spices were analyzed by electron spin resonance (EPR) signals. The results of this study lead to the conclusion that viscosimetry, thermoluminescence and electron spin resonance are analytical methods that can be use to detect whether spices and dehydrated vegetables were irradiated, specially when a combination of different methods was used

Exploring the Future of Fuel Loads in Tasmania, Australia: Shifts in Vegetation in Response to Changing Fire Weather, Productivity, and Fire Frequency

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Rebecca Mary Bernadette Harris

2018-04-01

Full Text Available Changes to the frequency of fire due to management decisions and climate change have the potential to affect the flammability of vegetation, with long-term effects on the vegetation structure and composition. Frequent fire in some vegetation types can lead to transformational change beyond which the vegetation type is radically altered. Such feedbacks limit our ability to project fuel loads under future climatic conditions or to consider the ecological tradeoffs associated with management burns. We present a “pathway modelling” approach to consider multiple transitional pathways that may occur under different fire frequencies. The model combines spatial layers representing current and future fire danger, biomass, flammability, and sensitivity to fire to assess potential future fire activity. The layers are derived from a dynamically downscaled regional climate model, attributes from a regional vegetation map, and information about fuel characteristics. Fire frequency is demonstrated to be an important factor influencing flammability and availability to burn and therefore an important determinant of future fire activity. Regional shifts in vegetation type occur in response to frequent fire, as the rate of change differs across vegetation type. Fire-sensitive vegetation types move towards drier, more fire-adapted vegetation quickly, as they may be irreversibly impacted by even a single fire, and require very long recovery times. Understanding the interaction between climate change and fire is important to identify appropriate management regimes to sustain fire-sensitive communities and maintain the distribution of broad vegetation types across the landscape.

Treatment of foods with 'soft-electrons' (low-energy electrons)

International Nuclear Information System (INIS)

Hayashi, Toru; Todoriki, Setsuko

2003-01-01

Electrons with energies of 300 keV or lower were defined as soft-electrons'. Soft-electrons can eradicate microorganisms residing on the surface of grains, pulses, spices, dehydrated vegetables, tea leaves and seeds, and reduce their microbial loads to levels lower than 10 CFU/g with little quality deterioration. Soft-electrons can inactivate insect pests infesting grains and pulses and inhibit sprouting of potatoes. (author)

Differentiate responses of soil structure to natural vegetation and artificial plantation in landslide hazard region of the West Qinling Mountains, China

Science.gov (United States)

Wang, X.; Huang, Z.; Zhao, Y.; Hong, M.

2017-12-01

Natural vegetation and artificial plantation are the most important measures for ecological restoration in soil erosion and landslide hazard-prone regions of China. Previous studies have demonstrated that both measures can significantly change the soil structure and decrease soil and water erosion. Few reports have compared the effects of the two contrasting measures on mechanical and hydrological properties and further tested the differentiate responses of soil structure. In the study areas, two vegetation restoration measures-natural vegetation restoration (NVR) and artificial plantation restoration (APR) compared with control site, with similar topographical and geological backgrounds were selected to investigate the different effects on soil structure based on eight-year ecological restoration projects. The results showed that the surface vegetation played an important role in releasing soil erosion and enhance soil structure stability through change the soil aggregates (SA) and total soil porosity (TSP). The SArestoration and conservation in geological hazard-prone regions.

River flow response to changes in vegetation cover in a South ...

African Journals Online (AJOL)

It was hypothesised in this study that annual river yield (river flow as a fraction of rainfall) in the Molenaars catchment near Paarl, South Africa co-varies with an index of green vegetation cover derived from satellite data (the normalised difference vegetation index, NDVI). The catchment was partitioned into 'upland' and ...

Investigation on the Patterns of Global Vegetation Change Using a Satellite-Sensed Vegetation Index

Directory of Open Access Journals (Sweden)

Ainong Li

2010-06-01

Full Text Available The pattern of vegetation change in response to global change still remains a controversial issue. A Normalized Difference Vegetation Index (NDVI dataset compiled by the Global Inventory Modeling and Mapping Studies (GIMMS was used for analysis. For the period 1982–2006, GIMMS-NDVI analysis indicated that monthly NDVI changes show homogenous trends in middle and high latitude areas in the northern hemisphere and within, or near, the Tropic of Cancer and Capricorn; with obvious spatio-temporal heterogeneity on a global scale over the past two decades. The former areas featured increasing vegetation activity during growth seasons, and the latter areas experienced an even greater amplitude in places where precipitation is adequate. The discussion suggests that one should be cautious of using the NDVI time-series to analyze local vegetation dynamics because of its coarse resolution and uncertainties.

Differential response of vegetation in Hulun Lake region at the northern margin of Asian summer monsoon to extreme cold events of the last deglaciation

Science.gov (United States)

Zhang, Shengrui; Xiao, Jule; Xu, Qinghai; Wen, Ruilin; Fan, Jiawei; Huang, Yun; Yamagata, Hideki

2018-06-01

The response of vegetation to extreme cold events during the last deglaciation is important for assessing the impact of possible extreme climatic events on terrestrial ecosystems under future global warming scenarios. Here, we present a detailed record of the development of regional vegetation in the northern margin of Asian summer monsoon during the last deglaciation (16,500-11,000 cal yr BP) based on a radiocarbon-dated high-resolution pollen record from Hulun Lake, northeast China. The results show that the regional vegetation changed from subalpine meadow-desert steppe to mixed coniferous and deciduous forest-typical steppe during the last deglaciation. However, its responses to the Heinrich event 1 (H1) and the Younger Dryas event (YD) were significantly different: during the H1 event, scattered sparse forest was present in the surrounding mountains, while within the lake catchment the vegetation cover was poor and was dominated by desert steppe. In contrast, during the YD event, deciduous forest developed and the proportion of coniferous forest increased in the mountains, the lake catchment was occupied by typical steppe. We suggest that changes in Northern Hemisphere summer insolation and land surface conditions (ice sheets and sea level) caused temperature and monsoonal precipitation variations that contributed to the contrasting vegetation response during the two cold events. We conclude that under future global warming scenarios, extreme climatic events may cause a deterioration of the ecological environment of the Hulun Lake region, resulting in increased coniferous forest and decreased total forest cover in the surrounding mountains, and a reduction in typical steppe in the lake catchment.

Response of cellulose nitrate track detectors to electron doses

CERN Document Server

Segovia, N; Moreno, A; Vazquez-Polo, G; Santamaría, T; Aranda, P; Hernández, A

1999-01-01

In order to study alternative dose determination methods, the bulk etching velocity and the latent track annealing of LR 115 track detectors was studied during electron irradiation runs from a Pelletron accelerator. For this purpose alpha irradiated and blank detectors were exposed to increasing electron doses from 10.5 to 317.5 kGy. After the irradiation with electrons the detectors were etched under routine conditions, except for the etching time, that was varied for each electron dose in order to reach a fixed residual thickness. The variation of the bulk etching velocity as a function of each one of the electron doses supplied, was interpolated in order to obtain dosimetric response curves. The observed annealing effect on the latent tracks is discussed as a function of the total electron doses supplied and the temperature.

36 CFR 1236.6 - What are agency responsibilities for electronic records management?

Science.gov (United States)

2010-07-01

... § 1236.6 What are agency responsibilities for electronic records management? Agencies must: (a... 36 Parks, Forests, and Public Property 3 2010-07-01 2010-07-01 false What are agency responsibilities for electronic records management? 1236.6 Section 1236.6 Parks, Forests, and Public Property...

Role of vegetation on river bank accretion

NARCIS (Netherlands)

Vargas Luna, A.

2016-01-01

There is rising awareness of the need to include the effects of vegetation in studies dealing with the morphological response of rivers. Vegetation growth on river banks and floodplains alters the river bed topography, reduces the bank erosion rates and enhances the development of new floodplains

Vulnerability and Resilience of Temperate Forest Landscapes to Broad-Scale Deforestation in Response to Changing Fire Regimes and Altered Post-Fire Vegetation Dynamics

Science.gov (United States)

Tepley, A. J.; Veblen, T. T.; Perry, G.; Anderson-Teixeira, K. J.

2015-12-01

In the face of on-going climatic warming and land-use change, there is growing concern that temperate forest landscapes could be near a tipping point where relatively small changes to the fire regime or altered post-fire vegetation dynamics could lead to extensive conversion to shrublands or savannas. To evaluate vulnerability and resilience to such conversion, we develop a simple model based on three factors we hypothesize to be key in predicting temperate forest responses to changing fire regimes: (1) the hazard rate (i.e., the probability of burning in the next year given the time since the last fire) in closed-canopy forests, (2) the hazard rate for recently-burned, open-canopy vegetation, and (3) the time to redevelop canopy closure following fire. We generate a response surface representing the proportions of the landscape potentially supporting closed-canopy forest and non-forest vegetation under nearly all combinations of these three factors. We then place real landscapes on this response surface to assess the type and magnitude of changes to the fire regime that would drive extensive forest loss. We show that the deforestation of much of New Zealand that followed initial human colonization and the introduction of a new ignition source ca. 750 years ago was essentially inevitable due to the slow rate of forest recovery after fire and the high flammability of post-fire vegetation. In North America's Pacific Northwest, by contrast, a predominantly forested landscape persisted despite two periods of widespread burning in the recent past due in large part to faster post-fire forest recovery and less pronounced differences in flammability between forests and the post-fire vegetation. We also assess the factors that could drive extensive deforestation in other regions to identify where management could reduce this potential and to guide field and modeling work to better understand the responses and ecological feedbacks to changing fire regimes.

Growth and Yield Responses of Vegetable Cowpea ( Vigna ...

African Journals Online (AJOL)

The amendment of acidic soil with lime application enhances nutrient availability for optimum vegetable cowpea production. Field experiments were conducted in the teaching and research farm of Michael Okpara University of Agriculture, Umudike during 2006 and 2007 cropping seasons to determine the growth and yield ...

Two electron response to an intense x-ray free electron laser pulse

International Nuclear Information System (INIS)

Moore, L R; Parker, J S; Meharg, K J; Armstrong, G S J; Taylor, K T

2009-01-01

New x-ray free electron lasers (FELs) promise an ultra-fast ultra-intense regime in which new physical phenomena, such as double core hole formation in at atom, should become directly observable. Ahead of x-ray FEL experiments, an initial key task is to theoretically explore such fundamental laser-atom interactions and processes. To study the response of a two-electron positive ion to an intense x-ray FEL pulse, our theoretical approach is a direct numerical integration, incorporating non-dipole Hamiltonian terms, of the full six-dimensional time-dependent Schroedinger equation. We present probabilities of double K-shell ionization in the two-electron positive ions Ne 8+ and Ar 16+ exposed to x-ray FEL pulses with frequencies in the range 50 au to 300 au and intensities in the range 10 17 to 10 22 W/cm 2 .

Characterization of electron-deficient chemical bonding of diborane with attosecond electron wavepacket dynamics and laser response

International Nuclear Information System (INIS)

Yonehara, Takehiro; Takatsuka, Kazuo

2009-01-01

We report a theoretical study of non-adiabatic electrons-nuclei coupled dynamics of diborane H 2 BH 2 BH 2 under several types of short pulse lasers. This molecule is known to have particularly interesting geometrical and electronic structures, which originate from the electron-deficient chemical bondings. We revisit the chemical bonding of diborane from the view point of electron wavepacket dynamics coupled with nuclear motions, and attempt to probe the characteristics of it by examining its response to intense laser fields. We study in the following three aspects, (i) bond formation of diborane by collision between two monoboranes, (ii) attosecond electron wavepacket dynamics in the ground state and first excited state by circularly polarized laser pulse, and (iii) induced fragmentation back to monoborane molecules by linearly polarized laser. The wave lengths of two types of laser field employed are 200 nm (in UV range) and 800 nm (in IR range), and we track the dynamics from hundreds of attoseconds up to few tens of femtoseconds. To this end, we apply the ab initio semiclassical Ehrenfest theory, into which the classical vector potential of a laser field is introduced. Basic features of the non-adiabatic response of electrons to the laser fields is elucidated in this scheme. To analyze the electronic wavepackets thus obtained, we figure out bond order density that is a spatial distribution of the bond order and bond order flux density arising only from the bonding regions, and so on. Main findings in this work are: (i) dimerization of monoboranes to diborane is so efficient that even intense laser is hard to prevent it; (ii) collective motions of electron flux emerge in the central BHHB bonding area in response to the circularly polarized laser fields; (iii) laser polarization with the direction of central two BH bonding vector is efficient for the cleavage of BH 3 -BH 3 ; and (iv) nuclear derivative coupling plays a critical role in the field induced

Antimutagenic and antigenotoxic effects of vegetable matrices on the activity of pesticides.

Science.gov (United States)

Isidori, M; Caterino, E; Criscuolo, E; Fatigati, V; Liguori, G; Parrella, A

2009-07-01

Two in vitro tests, one to detect bacterial mutagenicity (Ames test) on Salmonella typhimurium TA98, TA100, and TA1535 and the other the primary DNA damage (SOS Chromotest) on Escherichia coli PQ37, were applied to determine the overall genotoxic activity of 12 pesticides (azinphos methyl, chlorothalonil, chlorphyriphos ethyl, chlorphyriphos methyl, lambda-cyhalothrin, cypermethrin, cyprodinil, fenazaquin, fludioxonil, indoxacarb, iprodione and penconazol). These were detected by gas chromatography (GC) analysis with electron capture (ECD) and nitrogen phosphorus detection (NPD) in 18 samples of vegetables. Some extracts of vegetables, found positive for pesticides with GC, were subjected to the Ames test and SOS Chromotest to evaluate the possible antimutagenic and/or antigenotoxic effects of vegetable matrices. The same bioassays were also performed on the mixtures of pesticides found in these samples to evaluate whether interactions could occur between pesticides and be responsible for the possible antimutagenic and/or antigenotoxic effects of the contaminated matrices. Experiments were also carried out to compare the results found for contaminated vegetables with their content of antioxidant components. Significant differences in mutagenicity and genotoxicity were found among the pesticides selected for this study. Of the 12 pesticides tested, only azinphos methyl, cyprodinil, fludioxonil and iprodione were found to be positive for both S. typhimurium and E. coli. No mutagenic/genotoxic activity was found in the extracts of vegetables contaminated by pesticides. S. typhimurium TA1535 showed a strong positive mutagenic effect for the mixtures of pesticides while they were not able to induce the SOS system. The data concerning the content of polyphenols and the total reducing activity of the contaminated vegetables indicated high amounts of antioxidants that could explain the inhibitory effect on the activity of pesticides shown by vegetables.

Two electron response to an intense x-ray free electron laser pulse

Energy Technology Data Exchange (ETDEWEB)

Moore, L R; Parker, J S; Meharg, K J; Armstrong, G S J; Taylor, K T, E-mail: l.moore@qub.ac.u [DAMTP, David Bates Building, Queen' s University Belfast, Belfast, BT7 1NN (United Kingdom)

2009-11-01

New x-ray free electron lasers (FELs) promise an ultra-fast ultra-intense regime in which new physical phenomena, such as double core hole formation in at atom, should become directly observable. Ahead of x-ray FEL experiments, an initial key task is to theoretically explore such fundamental laser-atom interactions and processes. To study the response of a two-electron positive ion to an intense x-ray FEL pulse, our theoretical approach is a direct numerical integration, incorporating non-dipole Hamiltonian terms, of the full six-dimensional time-dependent Schroedinger equation. We present probabilities of double K-shell ionization in the two-electron positive ions Ne{sup 8+} and Ar{sup 16+} exposed to x-ray FEL pulses with frequencies in the range 50 au to 300 au and intensities in the range 10{sup 17} to 10{sup 22} W/cm{sup 2}.

Vegetation response to climate change : implications for Canada's conservation lands

International Nuclear Information System (INIS)

Scott, D.; Lemieux, C.

2003-01-01

Studies have shown that Canada's national parks are vulnerable to the impacts of climate change. A wide range of biophysical climate change impacts could affect the integrity of conservation lands in each region of Canada. This report examines the potential impact of climate change on landscape alterations and vegetation distribution in Canada's wide network of conservation lands. It also presents several ways to integrate climate change into existing conservation policy and adaptation strategies. Canada's conservation lands include provincial parks, migratory bird sanctuaries, national wildlife areas and wildlife protected areas. This is the first study to examine biome changes by applying an equilibrium Global Vegetation Model (GVM) to Canada's network of national park systems. Some of the policy and planning challenges posed by changes in landscape level vegetation were also addressed. The report indicates that in terms of potential changes to the biome classification of Canada's national forests, more northern biomes are projected to decrease. These northern biomes include the tundra, taiga and boreal conifer forests. 56 refs., 8 tabs., 6 figs

Waste vegetable oil survey report

Energy Technology Data Exchange (ETDEWEB)

MacLeod, R. [Science enterprise Algoma seA, Sault Ste. Marie, ON (Canada)

2009-02-06

This study was conducted to estimate potential sources of feedstock waste oils for biodiesel production in the Sault Ste. Marie region of Ontario. Two feedstocks were investigated over a period of several months, notably cooking oil and waste vegetable oil. The study was conducted to examine oil throughput, collection practices, and to gauge interest in local initiatives. A distribution list of commercial restaurant listings was developed, and surveys were conducted with members of private enterprises, city government, and non-profit stakeholders in the region. Average volumes of waste vegetable oil were presented for different types of restaurants. The various types of oil used in the restaurants were also quantified. Results of the study showed a positive public response to the idea of a local biodiesel initiative. Steak house, fast food, and Italian establishments generated the largest portion of waste vegetable oil amongst survey respondents. However, the highest response rates came from establishments with little or no oil consumption. Many franchise fast food restaurants are already in contracts with waste oil removal companies. 3 tabs., 3 figs.

Treatment of foods with 'soft-electrons' (low-energy electrons)

Energy Technology Data Exchange (ETDEWEB)

Hayashi, Toru [Japan International Research Center for Agricultural Sciences (JIRCAS), Tsukuba, Ibaraki (Japan); Todoriki, Setsuko [National Food Research Institute (NFRI), Tsukuba, Ibaraki (Japan)

2003-02-01

Electrons with energies of 300 keV or lower were defined as soft-electrons'. Soft-electrons can eradicate microorganisms residing on the surface of grains, pulses, spices, dehydrated vegetables, tea leaves and seeds, and reduce their microbial loads to levels lower than 10 CFU/g with little quality deterioration. Soft-electrons can inactivate insect pests infesting grains and pulses and inhibit sprouting of potatoes. (author)

Predicting gender differences in liking for vegetables and preference for a variety of vegetables among 11-year-old children.

Science.gov (United States)

Lehto, Elviira; Ray, Carola; Haukkala, Ari; Yngve, Agneta; Thorsdottir, Inga; Roos, Eva

2015-12-01

We studied the factors that predict liking for vegetables and preference for a variety of vegetables among schoolchildren. Additionally, we examined if there were gender differences in the predictors that explain the hypothesized higher scores in liking vegetables and preferences among girls. The data from the PRO GREENS project included 424 Finnish children (response rate 77%) aged 11 to 12. The children completed validated measures about social and environmental factors related to their liking for vegetables and preferences both at baseline 2009 and follow-up 2010. The associations were examined with regression and mediation analyses. The strongest predictors of both girls' and boys' liking and preferences were higher levels of eating vegetables together with the family, previous vegetable intake and a lower level of perceived barriers. Liking was additionally predicted by a lower level of parental demand that their child should eat vegetables. Girls reported higher levels of liking and preferences in the follow-up. This gender difference was mainly explained by girls' lower level of perceived barriers related to vegetable intake and girls' higher previous vegetable intake. Interventions that aim to increase the low vegetable intake among boys by increasing their liking for vegetables and preference for a variety of vegetables could benefit from targeting perceived barriers, namely boys' perception and values concerning the consumption of vegetables. Copyright © 2015 Elsevier Ltd. All rights reserved.

The response of Kodak EDR2 film in high-energy electron beams.

Science.gov (United States)

Gerbi, Bruce J; Dimitroyannis, Dimitri A

2003-10-01

Kodak XV2 film has been a key dosimeter in radiation therapy for many years. The advantages of the recently introduced Kodak EDR2 film for photon beam dosimetry have been the focus of several IMRT verification dosimetry publications. However, no description of this film's response to electron beams exists in the literature. We initiated a study to characterize the response and utility of this film for electron beam dosimetry. We exposed a series of EDR2 films to 6, 9, 12, 16, and 20 MeV electrons in addition to 6 and 18 MV x rays to develop standard characteristic curves. The linac was first calibrated to ensure that the delivered dose was known accurately. All irradiations were done at dmax in polystyrene for both photons and electrons, all films were from the same batch, and were developed at the same time. We also exposed the EDR2 films in a solid water phantom to produce central axis depth dose curves. These data were compared against percent depth dose curves measured in a water phantom using an IC-10 ion chamber, Kodak XV2 film, and a PTW electron diode. The response of this film was the same for both 6 and 18 MV x rays, but showed an apparent energy-dependent enhancement for electron beams. The response of the film also increased with increasing electron energy. This caused the percent depth dose curves using film to be shifted toward the surface compared to the ion chamber data.

Vegetation response to the "African Humid Period" termination in Central Cameroon (7° N – new pollen insight from Lake Mbalang

Directory of Open Access Journals (Sweden)

M. Servant

2010-05-01

Full Text Available A new pollen sequence from the Lake Mbalang (7°19´ N, 13°44´ E, 1110 m a.s.l. located on the eastern Adamawa plateau, in Central Cameroon, is presented in this paper to analyze the Holocene African Humid Period (AHP termination and related vegetation changes at 7° N in tropical Africa, completing an important transect for exploring shifts in the northern margin of the African Monsoon. This sequence, spanning the last 7000 cal yr BP, shows that the vegetation response to this transitional climatic period was marked by significant successional changes within the broad context of long-term aridification. Semi-deciduous/sub-montane forest retreat in this area is initially registered as early as ca. 6100 cal yr BP and modern savannah was definitely established at ca. 3000 cal yr BP and stabilized at ca. 2400 cal yr BP; but a slight forest regeneration episode is observed between ca. 5200 and ca. 4200 cal yr BP. In this area with modern high rainfall, increasing in the length of the dry season during the AHP termination linked to a contraction of the northern margin of the Intertropical Convergence Zone (ITCZ from ca. 6100 cal yr BP onward, probably associated with decreasing in cloud cover and/or fog frequency, has primarily controlled vegetation dynamics and above all the disappearance of the forested environment on the Adamawa plateau. Compared to previous studies undertaken in northern tropical and Central Africa, this work clearly shows that the response of vegetation to transitional periods between climatic extremes such as the AHP termination might be different in timing, mode and amplitude according to the regional climate of the study sites, but also according to the stability of vegetation before and during these climatic transitions.

Ecosystem response to removal of exotic riparian shrubs and a transition to upland vegetation

Science.gov (United States)

Reynolds, Lindsay V.; Cooper, David J.

2011-01-01

Understanding plant community change over time is essential for managing important ecosystems such as riparian areas. This study analyzed historic vegetation using soil seed banks and the effects of riparian shrub removal treatments and channel incision on ecosystem and plant community dynamics in Canyon de Chelly National Monument, Arizona. We focused on how seeds, nutrients, and ground water influence the floristic composition of post-treatment vegetation and addressed three questions: (1) How does pre-treatment soil seed bank composition reflect post-treatment vegetation composition? (2) How does shrub removal affect post-treatment riparian vegetation composition, seed rain inputs, and ground water dynamics? and (3) Is available soil nitrogen increased near dead Russian olive plants following removal and does this influence post-treatment vegetation? We analyzed seed bank composition across the study area, analyzed differences in vegetation, ground water levels, and seed rain between control, cut-stump and whole-plant removal areas, and compared soil nitrogen and vegetation near removed Russian olive to areas lacking Russian olive. The soil seed bank contained more riparian plants, more native and fewer exotic plants than the extant vegetation. Both shrub removal methods decreased exotic plant cover, decreased tamarisk and Russian olive seed inputs, and increased native plant cover after 2 years. Neither method increased ground water levels. Soil near dead Russian olive trees indicated a short-term increase in soil nitrogen following plant removal but did not influence vegetation composition compared to areas without Russian olive. Following tamarisk and Russian olive removal, our study sites were colonized by upland plant species. Many western North American rivers have tamarisk and Russian olive on floodplains abandoned by channel incision, river regulation or both. Our results are widely applicable to sites where drying has occurred and vegetation

Radiocesium cycling in vegetation and soil

International Nuclear Information System (INIS)

Dahlman, R.C.; Francis, C.W.; Tamura, T.

1975-01-01

Data on cesium dynamics in vegetation and soils are reviewed. Special emphasis is placed on typical environments in the southeastern United States. Clay minerals of soil, especially micaceous types, effectively fix cesium and remove it from biotic components of ecosystems. Fallout 137 Cs enters food chains principally by direct deposition on vegetation; uptake by the root pathway is usually less than direct contamination of plant foliage. Cesium-137 levels in vegetation of the southeastern U. S. Coastal Plain are estimated on the basis of direct deposition from the atmosphere and root uptake from soil. Estimated concentrations, based on current concepts of 137 Cs dynamics in vegetation and fixation in soil, are in good agreement with observed values of 137 Cs in vegetation collected in 1969 and 1970. Mechanisms of direct deposition and of increased uptake by roots due to the absence of micaceous clays adequately explain the higher levels of 137 Cs in vegetation of the Coastal Plain and thus are responsible for the elevated 137 Cs reported for milk of the Tampa, Fla., milkshed

The response of a radiophotoluminescent glass dosimeter in megavoltage photon and electron beams.

Science.gov (United States)

Araki, Fujio; Ohno, Takeshi

2014-12-01

This study investigated the response of a radiophotoluminescent glass dosimeter (RGD) in megavoltage photon and electron beams. The RGD response was compared with ion chamber measurements for 4-18 MV photons and 6-20 MeV electrons in plastic water phantoms. The response was also calculated via Monte Carlo (MC) simulations with EGSnrc/egs_chamber and Cavity user-codes, respectively. In addition, the response of the RGD cavity was analyzed as a function of field sizes and depths according to Burlin's general cavity theory. The perturbation correction factor, PQ, in the RGD cavity was also estimated from MC simulations for photon and electron beams. The calculated and measured RGD energy response at reference conditions with a 10 × 10 cm(2) field and 10 cm depth in photons was lower by up to 2.5% with increasing energy. The variation in RGD response in the field size range of 5 × 5 cm(2) to 20 × 20 cm(2) was 3.9% and 0.7%, at 10 cm depth for 4 and 18 MV, respectively. The depth dependence of the RGD response was constant within 1% for energies above 6 MV but it increased by 2.6% and 1.6% for a large (20 × 20 cm(2)) field at 4 and 6 MV, respectively. The dose contributions from photon interactions (1 - d) in the RGD cavity, according to Burlin's cavity theory, decreased with increasing energy and decreasing field size. The variation in (1 - d) between field sizes became larger with increasing depth for the lower energies of 4 and 6 MV. PQ for the RGD cavity was almost constant between 0.96 and 0.97 at 10 MV energies and above. Meanwhile, PQ depends strongly on field size and depth for 4 and 6 MV photons. In electron beams, the RGD response at a reference depth, dref, varied by less than 1% over the electron energy range but was on average 4% lower than the response for 6 MV photons. The RGD response for photon beams depends on both (1 - d) and perturbation effects in the RGD cavity. Therefore, it is difficult to predict the energy dependence of RGD response by

Response of shortgrass Plains vegetation to chronic and seasonally administered gamma radiation

Energy Technology Data Exchange (ETDEWEB)

Fraley, Jr., Leslie [Colorado State Univ., Fort Collins, CO (United States)

1971-08-01

In order to determine the effect of radiation on the structure of native shortgrass plains vegetation, an 8750 Ci 137Cs source was installed on the Central Plains Experimental Range near Nunn, Colorado; The experimental area was divided into 6 treatment sectors, a control, 2 sectors for chronic exposure (irradiation initiated April 1969 and continuing as of August 1971), and one each for spring, summer and late fall seasonal semi-acute (30 day), exposures which were administered during April, July and December, 1969, respectively. Community structure was measured by coefficient of community and diversity index. Yield was determined by clipping plots in September 1970 and visual estimates in September 1969 and 1970 for the grass-sedge component of the vegetation. Individual species sensitivity was determined by density data recorded in April, June and September of 1969 and 1970 and by a phenological index recorded at weekly intervals during the 1969 and 1970 growing seasons. The response of the vegetation was similar whether determined by coefficient of community or diversity with diversity being a more sensitive measure of effects. In the chronically exposed sectors, the exposure rate which resulted in a 50 per cent reduction in these 2 parameters (CC50 or D50) was still decreasing the second growing season and was approximately 18 R/hr for the CC50 as of June 1970 and 10 R/hr for the D50 as of September 1970. For the seasonally exposed sectors, the late fall period (December, 1969) was the most sensitive, summer (July, 1969) the least sensitive and spring (April, 1969) intermediate with CC50 and D50 values of 195 and 90, 240 and 222, and 120 and 74 R/hr for the spring, summer and late fall exposed sectors, respectively. Yield and density data indicated a rapid revegetation of the spring and summer exposed sectors during 1970 as a result of an influx of invader species such as Salsola kali tenuifolia, Chenopodium leptophyllum and Lepidium densiflorum and the

Pattern of NDVI-based vegetation greening along an altitudinal gradient in the eastern Himalayas and its response to global warming.

Science.gov (United States)

Li, Haidong; Jiang, Jiang; Chen, Bin; Li, Yingkui; Xu, Yuyue; Shen, Weishou

2016-03-01

The eastern Himalayas, especially the Yarlung Zangbo Grand Canyon Nature Reserve (YNR), is a global hotspot of biodiversity because of a wide variety of climatic conditions and elevations ranging from 500 to > 7000 m above sea level (a.s.l.). The mountain ecosystems at different elevations are vulnerable to climate change; however, there has been little research into the patterns of vegetation greening and their response to global warming. The objective of this paper is to examine the pattern of vegetation greening in different altitudinal zones in the YNR and its relationship with vegetation types and climatic factors. Specifically, the inter-annual change of the normalized difference vegetation index (NDVI) and its variation along altitudinal gradient between 1999 and 2013 was investigated using SPOT-VGT NDVI data and ASTER global digital elevation model (GDEM) data. We found that annual NDVI increased by 17.58% in the YNR from 1999 to 2013, especially in regions dominated by broad-leaved and coniferous forests at lower elevations. The vegetation greening rate decreased significantly as elevation increased, with a threshold elevation of approximately 3000 m. Rising temperature played a dominant role in driving the increase in NDVI, while precipitation has no statistical relationship with changes in NDVI in this region. This study provides useful information to develop an integrated management and conservation plan for climate change adaptation and promote biodiversity conservation in the YNR.

Response of nutrients, minerals, antioxidant leaf pigments, vitamins, polyphenol, flavonoid and antioxidant activity in selected vegetable amaranth under four soil water content.

Science.gov (United States)

Sarker, Umakanta; Oba, Shinya

2018-06-30

Four selected vegetable amaranths were grown under four soil water content to evaluate their response in nutrients, minerals, antioxidant leaf pigments, vitamins, polyphenol, flavonoid and total antioxidant activity (TAC). Vegetable amaranth was significantly affected by variety, soil water content and variety × soil water content interactions for all the traits studied. Increase in water stress, resulted in significant changes in proximate compositions, minerals (macro and micro), leaf pigments, vitamin, total polyphenol content (TPC), and total flavonoid content (TFC) of vegetable amaranth. Accessions VA14 and VA16 performed better for all the traits studied. Correlation study revealed a strong antioxidant scavenging activity of leaf pigments, ascorbic acid, TPC and TFC. Vegetable amaranth can tolerate soil water stress without compromising the high quality of the final product in terms of nutrients and antioxidant profiles. Therefore, it could be a promising alternative crop in semi-arid and dry areas and also during dry seasons. Copyright © 2018. Published by Elsevier Ltd.

Drought, climate change and vegetation response in the succulent karoo, South Africa

Directory of Open Access Journals (Sweden)

M. T. Hoffman

2009-12-01

Full Text Available For the winter-rainfall region of South Africa, the frequency of drought is predicted to increase over the next 100 years, with dire consequences for the vegetation of this biodiversity hotspot. We analysed historical 20th century rainfall records for six rainfall stations within the succulent karoo biome to determine if the signal of increasing drought frequency is already apparent, and whether mean annual rainfall is decreasing. We found no evidence for a decrease either in mean annual rainfall or in the incidence of drought, as measured by the Standardised Precipitation Index (SPI over the 20th century. Evidence points to a drying trend from 1900–1950 while no significant trend in rainfall and drought was found at most stations from 1951–2000. In a second analysis we synthesised the information concerning the response of adult succulent karoo biome plants and seedlings to extended drought conditions. General findings are that responses to drought differ between species, and that longevity is an important life history trait related to drought survival. Growth form is a poor predictor of drought response across the biome. There was a range of responses to drought among adult plants of various growth forms, and among non-succulent seedlings. Leaf-succulent seedlings, however, exhibited phenomenal drought resistance, the majority surviving drought long after all the experimentally comparative non-succulent seedlings had died. Our synthesis showed that previous studies on the impact of drought on succulent karoo biome plants differ greatly in terms of their location, sampling design, measured values and plant responses. A suite of coordinated long-term field observations, experiments and models are therefore needed to assess the response of succulent karoo biome species to key drought events as they occur over time and to integrate this information into conservation planning.

Post Fire Vegetation Recovery in Portugal

Science.gov (United States)

Gouveia, Celia; Bastos, Ana; DaCamara, Carlos; Trigo, Ricardo M.

2011-01-01

Fires in Portugal, as in the Mediterranean ecosystems, have a complex effect on vegetation regeneration due to the different responses of vegetation to the variety of fire regimes and to the complexity of landscape structures. A thorough evaluation of vegetation recovery after fire events becomes therefore crucial in land management. In 2005, Portugal suffered a strong damage from forest fires that damaged an area of 300 000 ha of forest and shrub. This year are particularly interesting because it is associated the severe drought of 2005. The aim of the present study is to identify large burnt scars in Portugal during the 2005 fire seasons and monitoring vegetation behaviour throughout the pre and the post fire periods. The mono-parametric model developed by Gouveia et al. (2010), based on monthly values of NDVI, at the 1km×1km spatial scale, as obtained from the VEGETATION-SPOT5 instrument, from 1999 to 2009, was used.

Assessing the vegetation condition impacts of the 2011 drought across the U.S. southern Great Plains using the vegetation drought response index (VegDRI)

Science.gov (United States)

Tadesse, Tsegaye; Wardlow, Brian D.; Brown, Jesslyn F.; Svoboda, Mark; Hayes, Michael; Fuchs, Brian; Gutzmer, Denise

2015-01-01

The vegetation drought response index (VegDRI), which combines traditional climate- and satellite-based approaches for assessing vegetation conditions, offers new insights into assessing the impacts of drought from local to regional scales. In 2011, the U.S. southern Great Plains, which includes Texas, Oklahoma, and New Mexico, was plagued by moderate to extreme drought that was intensified by an extended period of record-breaking heat. The 2011 drought presented an ideal case study to evaluate the performance of VegDRI in characterizing developing drought conditions. Assessment of the spatiotemporal drought patterns represented in the VegDRI maps showed that the severity and patterns of the drought across the region corresponded well to the record warm temperatures and much-below-normal precipitation reported by the National Climatic Data Center and the sectoral drought impacts documented by the Drought Impact Reporter (DIR). VegDRI values and maps also showed the evolution of the drought signal before the Las Conchas Fire (the largest fire in New Mexico’s history). Reports in the DIR indicated that the 2011 drought had major adverse impacts on most rangeland and pastures in Texas and Oklahoma, resulting in total direct losses of more than $12 billion associated with crop, livestock, and timber production. These severe impacts on vegetation were depicted by the VegDRI at subcounty, state, and regional levels. This study indicates that the VegDRI maps can be used with traditional drought indicators and other in situ measures to help producers and government officials with various management decisions, such as justifying disaster assistance, assessing fire risk, and identifying locations to move livestock for grazing.

Nonadiabatic electron response in the Hasegawa-Wakatani equations

International Nuclear Information System (INIS)

Stoltzfus-Dueck, T.; Scott, B. D.; Krommes, J. A.

2013-01-01

Tokamak edge turbulence is strongly influenced by parallel electron physics, which relaxes density and potential fluctuations towards electron adiabatic response. Beginning with the paradigmatic Hasegawa-Wakatani equations (HWEs) for resistive tokamak edge turbulence, a unique decomposition of the electric potential (φ) into adiabatic (a) and nonadiabatic (b) portions is derived, based on the requirement that a neither drive nor respond to the parallel current j ∥ . The form of the decomposition clarifies that, at perpendicular scales large relative to the sound radius, the electron adiabatic response controls the nonzonal φ, not the fluctuating density n. Simple energy balance arguments allow one to rigorously bound the ratio of rms nonzonal nonadiabatic fluctuations (b(tilde sign)) relative to adiabatic ones (ã). The role of the vorticity nonlinearity in transferring energy between adiabatic and nonadiabatic fluctuations aids intuitive understanding of self-sustained turbulence in the HWEs. When the normalized parallel resistivity is weak, b(tilde sign) becomes effectively slaved, allowing the reduction to an approximate one-field model that remains valid for strong turbulence. In addition to guiding physical intuition, the one-field reduction should greatly ease further analytical manipulations. Direct numerical simulation of the 2D HWEs confirms the convergence of the asymptotic formula for b(tilde sign)

Responses of Vegetation Cover to Environmental Change in Large Cities of China

Directory of Open Access Journals (Sweden)

Kai Jin

2018-01-01

Full Text Available Vegetation cover is crucial for the sustainability of urban ecosystems; however, this cover has been undergoing substantial changes in cities. Based on climate data, city statistical data, nighttime light data and the Normalized Difference Vegetation Index (NDVI dataset, we investigate the spatiotemporal variations of climate factors, urban lands and vegetation cover in 71 large cities of China during 1998–2012, and explore their correlations. A regression model between growing-season NDVI (G-NDVI and urban land proportion (PU is built to quantify the impact of urbanization on vegetation cover change. The results indicate that the spatiotemporal variations of temperature, precipitation, PU and G-NDVI are greatly different among the 71 cities which experienced rapid urbanization. The spatial difference of G-NDVI is closely related to diverse climate conditions, while the inter-annual variations of G-NDVI are less sensitive to climate changes. In addition, there is a negative correlation between G-NDVI trend and PU change, indicating vegetation cover in cities have been negatively impacted by urbanization. For most of the inland cities, the urbanization impacts on vegetation cover in urban areas are more severe than in suburban areas. But the opposite occurs in 17 cities mainly located in the coastal areas which have been undergoing the most rapid urbanization. Overall, the impacts of urbanization on G-NDVI change are estimated to be −0.026 per decade in urban areas and −0.015 per decade in suburban areas during 1998–2012. The long-term developments of cities would persist and continue to impact on the environmental change and sustainability. We use a 15-year window here as a case study, which implies the millennia of human effects on the natural biotas and warns us to manage landscapes and preserve ecological environments properly.

Demand Analysis of Selected Fruits and Vegetables in Oman

Directory of Open Access Journals (Sweden)

A. Omezzine

1998-01-01

Full Text Available Consumer behavior and prospective changes in demand of food product have a significant impact on production and distribution decisions. Consumer responsiveness to changes in prices, income and other demand determinants is very important to production and market decision-makers. The present study estimates demand responses for selected fruits and vegetables in Oman using consumer aggregated national data. The main objective is to generate information needed for making public as well as private decisions. Results indicate that most fruit and vegetable consumers respond to price, and income changes in the expected manner. Responses are different from one commodity to another depending on its nature and importance in the consumer's diet habits. In a few cases income is not a significant determinant of the demand. Moreover, many fruits and vegetables have shown a relationship of substitution and complementary consistent with Omani diet. These results are useful in farmers and distributers to allow them to adjust their production and marketing services according to the consumer’s response.

Responses of the Carbon Storage and Sequestration Potential of Forest Vegetation to Temperature Increases in Yunnan Province, SW China

Directory of Open Access Journals (Sweden)

Ruiwu Zhou

2018-04-01

Full Text Available The distribution of forest vegetation and forest carbon sequestration potential are significantly influenced by climate change. In this study, a map of the current distribution of vegetation in Yunnan Province was compiled based on data from remote sensing imagery from the Advanced Land Observing Satellite (ALOS from 2008 to 2011. A classification and regression tree (CART model was used to predict the potential distribution of the main forest vegetation types in Yunnan Province and estimate the changes in carbon storage and carbon sequestration potential (CSP in response to increasing temperature. The results show that the current total forest area in Yunnan Province is 1.86 × 107 ha and that forest covers 48.63% of the area. As the temperature increases, the area of forest distribution first increases and then decreases, and it decreases by 11% when the temperature increases from 1.5 to 2 °C. The mean carbon density of the seven types of forest vegetation in Yunnan Province is 84.69 Mg/ha. The total carbon storage of the current forest vegetation in Yunnan Province is 871.14 TgC, and the CSP is 1100.61 TgC. The largest CSP (1114.82 TgC occurs when the temperature increases by 0.5 °C. Incremental warming of 2 °C will sharply decrease the forest CSP, especially in those regions with mature coniferous forest vegetation. Semi-humid evergreen broad-leaved forests were highly sensitive to temperature changes, and the CSP of these forests will decrease with increasing temperature. Warm-hot coniferous forests have the greatest CSP in all simulation scenarios except the scenario of a 2 °C temperature increase. These results indicate that temperature increases can influence the CSP in Yunnan Province, and the largest impact emerged in the 2 °C increase scenario.

Response of a relativistic quantum magnetized electron gas

International Nuclear Information System (INIS)

Melrose, Donald B; Weise, Jeanette I

2009-01-01

The response 4-tensor is derived for a spin-independent, relativistic magnetized quantum electron gas. The sum over spins is carried out both directly and using a procedure due to Ritus. The 4-tensor components are written in terms of a sum over the two solutions of the resonance condition for the particle 4-momentum. It is shown that the dispersive properties may be described in terms of a single plasma dispersion function, for arbitrary occupation numbers for electrons and positrons in each Landau level. The plasma dispersion function is evaluated explicitly in the completely degenerate and nondegenerate thermal limits. The perpendicular wave number appears in the arguments of J-functions, which are proportional to generalized Laguerre polynomials, but not in the plasma dispersion function. The result generalizes a known form for the response tensor for parallel propagation (in the completely degenerate case), when the J-functions are either zero or unity, to arbitrary angles of propagation.

Vegetation response to invasive Tamarix control in southwestern U.S. rivers: a collaborative study including 416 sites.

Science.gov (United States)

González, Eduardo; Sher, Anna A; Anderson, Robert M; Bay, Robin F; Bean, Daniel W; Bissonnete, Gabriel J; Bourgeois, Bérenger; Cooper, David J; Dohrenwend, Kara; Eichhorst, Kim D; El Waer, Hisham; Kennard, Deborah K; Harms-Weissinger, Rebecca; Henry, Annie L; Makarick, Lori J; Ostoja, Steven M; Reynolds, Lindsay V; Robinson, W Wright; Shafroth, Patrick B

2017-09-01

Most studies assessing vegetation response following control of invasive Tamarix trees along southwestern U.S. rivers have been small in scale (e.g., river reach), or at a regional scale but with poor spatial-temporal replication, and most have not included testing the effects of a now widely used biological control. We monitored plant composition following Tamarix control along hydrologic, soil, and climatic gradients in 244 treated and 172 reference sites across six U.S. states. This represents the largest comprehensive assessment to date on the vegetation response to the four most common Tamarix control treatments. Biocontrol by a defoliating beetle (treatment 1) reduced the abundance of Tamarix less than active removal by mechanically using hand and chain-saws (2), heavy machinery (3) or burning (4). Tamarix abundance also decreased with lower temperatures, higher precipitation, and follow-up treatments for Tamarix resprouting. Native cover generally increased over time in active Tamarix removal sites, however, the increases observed were small and was not consistently increased by active revegetation. Overall, native cover was correlated to permanent stream flow, lower grazing pressure, lower soil salinity and temperatures, and higher precipitation. Species diversity also increased where Tamarix was removed. However, Tamarix treatments, especially those generating the highest disturbance (burning and heavy machinery), also often promoted secondary invasions of exotic forbs. The abundance of hydrophytic species was much lower in treated than in reference sites, suggesting that management of southwestern U.S. rivers has focused too much on weed control, overlooking restoration of fluvial processes that provide habitat for hydrophytic and floodplain vegetation. These results can help inform future management of Tamarix-infested rivers to restore hydrogeomorphic processes, increase native biodiversity and reduce abundance of noxious species. © 2017 by the

A review of fire effects on vegetation and soils in the Great Basin region: response and ecological site characteristics

Science.gov (United States)

Miller, Richard F.; Chambers, Jeanne C.; Pyke, David A.; Pierson, Fred B.; Williams, C. Jason

2013-01-01

This review synthesizes the state of knowledge on fire effects on vegetation and soils in semi-arid ecosystems in the Great Basin Region, including the central and northern Great Basin and Range, Columbia River Basin, and the Snake River Plain. We summarize available literature related to: (1) the effects of environmental gradients, ecological site, and vegetation characteristics on resilience to disturbance and resistance to invasive species; (2) the effects of fire on individual plant species and communities, biological soil crusts, seed banks, soil nutrients, and hydrology; and (3) the role of fire severity, fire versus fire surrogate treatments, and post-fire grazing in determining ecosystem response. From this, we identify knowledge gaps and present a framework for predicting plant successional trajectories following wild and prescribed fires and fire surrogate treatments. Possibly the three most important ecological site characteristics that influence a site’s resilience (ability of the ecological site to recover from disturbance) and resistance to invasive species are soil temperature/moisture regimes and the composition and structure of vegetation on the ecological site just prior to the disturbance event.

[Differences of vegetation phenology monitoring by remote sensing based on different spectral vegetation indices.

Science.gov (United States)

Zuo, Lu; Wang, Huan Jiong; Liu, Rong Gao; Liu, Yang; Shang, Rong

2018-02-01

Vegetation phenology is a comprehensive indictor for the responses of terrestrial ecosystem to climatic and environmental changes. Remote sensing spectrum has been widely used in the extraction of vegetation phenology information. However, there are many differences between phenology extracted by remote sensing and site observations, with their physical meaning remaining unclear. We selected one tile of MODIS data in northeastern China (2000-2014) to examine the SOS and EOS differences derived from the normalized difference vegetation index (NDVI) and the simple ratio vegetation index (SR) based on both the red and near-infrared bands. The results showed that there were significant differences between NDVI-phenology and SR-phenology. SOS derived from NDVI averaged 18.9 days earlier than that from SR. EOS derived from NDVI averaged 19.0 days later than from SR. NDVI-phenology had a longer growing season. There were significant differences in the inter-annual variation of phenology from NDVI and SR. More than 20% of the pixel SOS and EOS derived from NDVI and SR showed the opposite temporal trend. These results caused by the seasonal curve characteristics and noise resistance differences of NDVI and SR. The observed data source of NDVI and SR were completely consistent, only the mathematical expressions were different, but phenology results were significantly different. Our results indicated that vegetation phenology monitoring by remote sensing is highly dependent on the mathematical expression of vegetation index. How to establish a reliable method for extracting vegetation phenology by remote sensing needs further research.

Impact of electron irradiation on particle track etching response in ...

Indian Academy of Sciences (India)

In the present work, attempts have been made to investigate the modification in particle track etching response of polyallyl diglycol carbonate (PADC) due to impact of 2 MeV electrons. PADC samples pre-irradiated to 1, 10, 20, 40, 60, 80 and 100 Mrad doses of 2 MeV electrons were further exposed to 140 MeV 28Si beam ...

Vegetation Description, Rare Plant Inventory, and Vegetation Monitoring for Craig Mountain, Idaho.

Energy Technology Data Exchange (ETDEWEB)

Mancuso, Michael; Moseley, Robert

1994-12-01

The Craig Mountain Wildlife Mitigation Area was purchased by Bonneville Power Administration (BPA) as partial mitigation for wildlife losses incurred with the inundation of Dworshak Reservoir on the North Fork Clearwater River. Upon completion of the National Environmental Protection Act (NEPA) process, it is proposed that title to mitigation lands will be given to the Idaho Department of Fish and Game (IDFG). Craig Mountain is located at the northern end of the Hells Canyon Ecosystem. It encompasses the plateau and steep canyon slopes extending from the confluence of the Snake and Salmon rivers, northward to near Waha, south of Lewiston, Idaho. The forested summit of Craig Mountain is characterized by gently rolling terrain. The highlands dramatically break into the canyons of the Snake and Salmon rivers at approximately the 4,700 foot contour. The highly dissected canyons are dominated by grassland slopes containing a mosaic of shrubfield, riparian, and woodland habitats. During the 1993 and 1994 field seasons, wildlife, habitat/vegetation, timber, and other resources were systematically inventoried at Craig Mountain to provide Fish and Game managers with information needed to draft an ecologically-based management plan. The results of the habitat/vegetation portion of the inventory are contained in this report. The responsibilities for the Craig Mountain project included: (1) vegetation data collection, and vegetation classification, to help produce a GIS-generated Craig Mountain vegetation map, (2) to determine the distribution and abundance of rare plants populations and make recommendations concerning their management, and (3) to establish a vegetation monitoring program to evaluate the effects of Fish and Game management actions, and to assess progress towards meeting habitat mitigation goals.

Vegetation description, rare plant inventory, and vegetation monitoring for Craig Mountain, Idaho

International Nuclear Information System (INIS)

Mancuso, M.; Moseley, R.

1994-12-01

The Craig Mountain Wildlife Mitigation Area was purchased by Bonneville Power Administration (BPA) as partial mitigation for wildlife losses incurred with the inundation of Dworshak Reservoir on the North Fork Clearwater River. Upon completion of the National Environmental Protection Act (NEPA) process, it is proposed that title to mitigation lands will be given to the Idaho Department of Fish and Game (IDFG). Craig Mountain is located at the northern end of the Hells Canyon Ecosystem. It encompasses the plateau and steep canyon slopes extending from the confluence of the Snake and Salmon rivers, northward to near Waha, south of Lewiston, Idaho. The forested summit of Craig Mountain is characterized by gently rolling terrain. The highlands dramatically break into the canyons of the Snake and Salmon rivers at approximately the 4,700 foot contour. The highly dissected canyons are dominated by grassland slopes containing a mosaic of shrubfield, riparian, and woodland habitats. During the 1993 and 1994 field seasons, wildlife, habitat/vegetation, timber, and other resources were systematically inventoried at Craig Mountain to provide Fish and Game managers with information needed to draft an ecologically-based management plan. The results of the habitat/vegetation portion of the inventory are contained in this report. The responsibilities for the Craig Mountain project included: (1) vegetation data collection, and vegetation classification, to help produce a GIS-generated Craig Mountain vegetation map, (2) to determine the distribution and abundance of rare plants populations and make recommendations concerning their management, and (3) to establish a vegetation monitoring program to evaluate the effects of Fish and Game management actions, and to assess progress towards meeting habitat mitigation goals

Green Infrastructure Increases Biogeochemical Responsiveness, Vegetation Growth and Decreases Runoff in a Semi-Arid City, Tucson, AZ, USA

Science.gov (United States)

Meixner, T.; Papuga, S. A.; Luketich, A. M.; Rockhill, T.; Gallo, E. L.; Anderson, J.; Salgado, L.; Pope, K.; Gupta, N.; Korgaonkar, Y.; Guertin, D. P.

2017-12-01

Green Infrastructure (GI) is often viewed as a mechanism to minimize the effects of urbanization on hydrology, water quality, and other ecosystem services (including the urban heat island). Quantifying the effects of GI requires field measurements of the dimensions of biogeochemical, ecosystem, and hydrologic function that we expect GI to impact. Here we investigated the effect of GI features in Tucson, Arizona which has a low intensity winter precipitation regime and a high intensity summer regime. We focused on understanding the effect of GI on soil hydraulic and biogeochemical properties as well as the effect on vegetation and canopy temperature. Our results demonstrate profound changes in biogeochemical and hydrologic properties and vegetation growth between GI systems and nearby control sites. In terms of hydrologic properties GI soils had increased water holding capacity and hydraulic conductivity. GI soils also have higher total carbon, total nitrogen, and organic matter in general than control soils. Furthermore, we tested the sampled soils (control and GI) for differences in biogeochemical response upon wetting. GI soils had larger respiration responses indicating greater biogeochemical activity overall. Long-term Lidar surveys were used to investigate the differential canopy growth of GI systems versus control sites. The results of this analysis indicate that while a significant amount of time is needed to observe differences in canopy growth GI features due increase tree size and thus likely impact street scale ambient temperatures. Additionally monitoring of transpiration, soil moisture, and canopy temperature demonstrates that GI features increase vegetation growth and transpiration and reduce canopy temperatures. These biogeochemical and ecohydrologic results indicate that GI can increase the biogeochemical processing of soils and increase tree growth and thus reduce urban ambient temperatures.

Response of vegetation NDVI to climatic extremes in the arid region of Central Asia: a case study in Xinjiang, China

Science.gov (United States)

Yao, Junqiang; Chen, Yaning; Zhao, Yong; Mao, Weiyi; Xu, Xinbing; Liu, Yang; Yang, Qing

2018-02-01

Observed data showed the climatic transition from warm-dry to warm-wet in Xinjiang during the past 30 years and will probably affect vegetation dynamics. Here, we analyze the interannual change of vegetation index based on the satellite-derived normalized difference vegetation index (NDVI) with temperature and precipitation extreme over the Xinjiang, using the 8-km NDVI third-generation (NDVI3g) from the Global Inventory Modelling and Mapping Studies (GIMMS) from 1982 to 2010. Few previous studies analyzed the link between climate extremes and vegetation response. From the satellite-based results, annual NDVI significantly increased in the first two decades (1981-1998) and then decreased after 1998. We show that the NDVI decrease over the past decade may conjointly be triggered by the increases of temperature and precipitation extremes. The correlation analyses demonstrated that the trends of NDVI was close to the trend of extreme precipitation; that is, consecutive dry days (CDD) and torrential rainfall days (R24) positively correlated with NDVI during 1998-2010. For the temperature extreme, while the decreases of NDVI correlate positively with warmer mean minimum temperature ( Tnav), it correlates negatively with the number of warmest night days ( Rwn). The results suggest that the climatic extremes have possible negative effects on the ecosystem.

Toward a mechanistic modeling of nitrogen limitation on vegetation dynamics.

Science.gov (United States)

Xu, Chonggang; Fisher, Rosie; Wullschleger, Stan D; Wilson, Cathy J; Cai, Michael; McDowell, Nate G

2012-01-01

Nitrogen is a dominant regulator of vegetation dynamics, net primary production, and terrestrial carbon cycles; however, most ecosystem models use a rather simplistic relationship between leaf nitrogen content and photosynthetic capacity. Such an approach does not consider how patterns of nitrogen allocation may change with differences in light intensity, growing-season temperature and CO(2) concentration. To account for this known variability in nitrogen-photosynthesis relationships, we develop a mechanistic nitrogen allocation model based on a trade-off of nitrogen allocated between growth and storage, and an optimization of nitrogen allocated among light capture, electron transport, carboxylation, and respiration. The developed model is able to predict the acclimation of photosynthetic capacity to changes in CO(2) concentration, temperature, and radiation when evaluated against published data of V(c,max) (maximum carboxylation rate) and J(max) (maximum electron transport rate). A sensitivity analysis of the model for herbaceous plants, deciduous and evergreen trees implies that elevated CO(2) concentrations lead to lower allocation of nitrogen to carboxylation but higher allocation to storage. Higher growing-season temperatures cause lower allocation of nitrogen to carboxylation, due to higher nitrogen requirements for light capture pigments and for storage. Lower levels of radiation have a much stronger effect on allocation of nitrogen to carboxylation for herbaceous plants than for trees, resulting from higher nitrogen requirements for light capture for herbaceous plants. As far as we know, this is the first model of complete nitrogen allocation that simultaneously considers nitrogen allocation to light capture, electron transport, carboxylation, respiration and storage, and the responses of each to altered environmental conditions. We expect this model could potentially improve our confidence in simulations of carbon-nitrogen interactions and the vegetation

Toward a Mechanistic Modeling of Nitrogen Limitation on Vegetation Dynamics

Science.gov (United States)

Xu, Chonggang; Fisher, Rosie; Wullschleger, Stan D.; Wilson, Cathy J.; Cai, Michael; McDowell, Nate G.

2012-01-01

Nitrogen is a dominant regulator of vegetation dynamics, net primary production, and terrestrial carbon cycles; however, most ecosystem models use a rather simplistic relationship between leaf nitrogen content and photosynthetic capacity. Such an approach does not consider how patterns of nitrogen allocation may change with differences in light intensity, growing-season temperature and CO2 concentration. To account for this known variability in nitrogen-photosynthesis relationships, we develop a mechanistic nitrogen allocation model based on a trade-off of nitrogen allocated between growth and storage, and an optimization of nitrogen allocated among light capture, electron transport, carboxylation, and respiration. The developed model is able to predict the acclimation of photosynthetic capacity to changes in CO2 concentration, temperature, and radiation when evaluated against published data of Vc,max (maximum carboxylation rate) and Jmax (maximum electron transport rate). A sensitivity analysis of the model for herbaceous plants, deciduous and evergreen trees implies that elevated CO2 concentrations lead to lower allocation of nitrogen to carboxylation but higher allocation to storage. Higher growing-season temperatures cause lower allocation of nitrogen to carboxylation, due to higher nitrogen requirements for light capture pigments and for storage. Lower levels of radiation have a much stronger effect on allocation of nitrogen to carboxylation for herbaceous plants than for trees, resulting from higher nitrogen requirements for light capture for herbaceous plants. As far as we know, this is the first model of complete nitrogen allocation that simultaneously considers nitrogen allocation to light capture, electron transport, carboxylation, respiration and storage, and the responses of each to altered environmental conditions. We expect this model could potentially improve our confidence in simulations of carbon-nitrogen interactions and the vegetation feedbacks

Toward a mechanistic modeling of nitrogen limitation on vegetation dynamics.

Directory of Open Access Journals (Sweden)

Chonggang Xu

Full Text Available Nitrogen is a dominant regulator of vegetation dynamics, net primary production, and terrestrial carbon cycles; however, most ecosystem models use a rather simplistic relationship between leaf nitrogen content and photosynthetic capacity. Such an approach does not consider how patterns of nitrogen allocation may change with differences in light intensity, growing-season temperature and CO(2 concentration. To account for this known variability in nitrogen-photosynthesis relationships, we develop a mechanistic nitrogen allocation model based on a trade-off of nitrogen allocated between growth and storage, and an optimization of nitrogen allocated among light capture, electron transport, carboxylation, and respiration. The developed model is able to predict the acclimation of photosynthetic capacity to changes in CO(2 concentration, temperature, and radiation when evaluated against published data of V(c,max (maximum carboxylation rate and J(max (maximum electron transport rate. A sensitivity analysis of the model for herbaceous plants, deciduous and evergreen trees implies that elevated CO(2 concentrations lead to lower allocation of nitrogen to carboxylation but higher allocation to storage. Higher growing-season temperatures cause lower allocation of nitrogen to carboxylation, due to higher nitrogen requirements for light capture pigments and for storage. Lower levels of radiation have a much stronger effect on allocation of nitrogen to carboxylation for herbaceous plants than for trees, resulting from higher nitrogen requirements for light capture for herbaceous plants. As far as we know, this is the first model of complete nitrogen allocation that simultaneously considers nitrogen allocation to light capture, electron transport, carboxylation, respiration and storage, and the responses of each to altered environmental conditions. We expect this model could potentially improve our confidence in simulations of carbon-nitrogen interactions and the

Monitoring responses of Mason Pine to acid rain in China based on remote sensing vegetation index

International Nuclear Information System (INIS)

Jin, Jiaxin; Jiang, Hong; Zhang, Xiuying; Wang, Ying; Hou, Chunliang

2014-01-01

Since the 1970s, acid rain has remained in the public spotlight in both Europe and the United States and recently has emerged as an important problem in other regions such as Southeast Asia. To reveal responses of Masson Pine to acid rain during a long time series in central China, we used the interpolation dataset of acid rain and the Global Inventory Modeling and Mapping Studies (GIMMS) normalized difference vegetation index (NDVI) data to derive the monthly pH and NDVI trajectories based on acidity gradients from 1992 to 2006. Then we analyzed inter-annual and seasonal variation of vegetation growth by improved sinusoidal fitting and regression analysis. In the environment of strong acidity and moderate acidity, the growth of Masson Pine was inhibited during the study period, while the slight acidity promoted growth of Masson Pine to some extent. For the multi-year monthly changing trend of NDVI, late spring to mid autumn, the NDVI showed a decreasing trend, especially in June, while from late autumn to the following spring, the NDVI showed a rising tendency, specifically in December and March

Biofilm formation enhances Helicobacter pylori survivability in vegetables.

Science.gov (United States)

Ng, Chow Goon; Loke, Mun Fai; Goh, Khean Lee; Vadivelu, Jamuna; Ho, Bow

2017-04-01

To date, the exact route and mode of transmission of Helicobacter pylori remains elusive. The detection of H. pylori in food using molecular approaches has led us to postulate that the gastric pathogen may survive in the extragastric environment for an extended period. In this study, we show that H. pylori prolongs its survival by forming biofilm and micro-colonies on vegetables. The biofilm forming capability of H. pylori is both strain and vegetable dependent. H. pylori strains were classified into high and low biofilm formers based on their highest relative biofilm units (BU). High biofilm formers survived longer on vegetables compared to low biofilm formers. The bacteria survived better on cabbage compared to other vegetables tested. In addition, images captured on scanning electron and confocal laser scanning microscopes revealed that the bacteria were able to form biofilm and reside as micro-colonies on vegetable surfaces, strengthening the notion of possible survival of H. pylori on vegetables for an extended period of time. Taken together, the ability of H. pylori to form biofilm on vegetables (a common food source for human) potentially plays an important role in its survival, serving as a mode of transmission of H. pylori in the extragastric environment. Copyright © 2016 Elsevier Ltd. All rights reserved.

Response of the mean global vegetation distribution to interannual climate variability

Energy Technology Data Exchange (ETDEWEB)

Notaro, Michael [University of Wisconsin-Madison, Center for Climatic Research, Madison, WI (United States)

2008-06-15

The impact of interannual variability in temperature and precipitation on global terrestrial ecosystems is investigated using a dynamic global vegetation model driven by gridded climate observations for the twentieth century. Contrasting simulations are driven either by repeated mean climatology or raw climate data with interannual variability included. Interannual climate variability reduces net global vegetation cover, particularly over semi-arid regions, and favors the expansion of grass cover at the expense of tree cover, due to differences in growth rates, fire impacts, and interception. The area burnt by global fires is substantially enhanced by interannual precipitation variability. The current position of the central United States' ecotone, with forests to the east and grasslands to the west, is largely attributed to climate variability. Among woody vegetation, climate variability supports expanded deciduous forest growth and diminished evergreen forest growth, due to difference in bioclimatic limits, leaf longevity, interception rates, and rooting depth. These results offer insight into future ecosystem distributions since climate models generally predict an increase in climate variability and extremes. (orig.)

Terrestrial transect study on driving mechanism of vegetation changes

Institute of Scientific and Technical Information of China (English)

2008-01-01

In terms of Chinese climate-vegetation model based on the classification of plant functional types, to- gether with climatic data from 1951 to 1980 and two future climatic scenarios (SRES-A2 and SRES-B2) in China from the highest and the lowest emission scenarios of greenhouse gases, the distribution patterns of vegetation types and their changes along the Northeast China Transect (NECT) and the North-South Transect of Eastern China (NSTEC) were simulated in order to understand the driving mechanisms of vegetation changes under climatic change. The results indicated that the vegetation distribution patterns would change significantly under future climate, and the major factors driving the vegetation changes were water and heat. However, the responses of various vegetation types to the changes in water and heat factors were obviously different. The vegetation changes were more sensi- tive to heat factors than to water factors. Thus, in the future climate warming will significantly affect vegetation distribution patterns.

Response of multi-strip multi-gap resistive plate chamber using pulsed electron beam

International Nuclear Information System (INIS)

Datta Pramanik, U.; Chakraborty, S.; Rahaman, A.; Ray, J.; Chatterjee, S.; Bemmerer, D.; Elekes, Z.; Kempe, M.; Sobiella, M.; Stach, D.; Wagner, A.; Yakorev, D.; Leifels, Y.; Simon, H.

2011-01-01

A prototype of Multi-strip Multi-gap Resistive Plate Chamber (MMRPC) with active area 40 cm x 20 cm has been developed at SINP, Kolkata. Electron response of the developed detector was studied using the electron linac ELBE at Forschungszentrum Dresden-Rossendorf. The development of this detector started with the aim of developing a neutron detector but this ultrafast timing detector can be used efficiently for the purpose of medical imaging, security purpose and detection of minimum ionising particle. In this article detailed analysis of electron response to our developed MMRPC will be presented

Application of Macro Response Monte Carlo method for electron spectrum simulation

International Nuclear Information System (INIS)

Perles, L.A.; Almeida, A. de

2007-01-01

During the past years several variance reduction techniques for Monte Carlo electron transport have been developed in order to reduce the electron computation time transport for absorbed dose distribution. We have implemented the Macro Response Monte Carlo (MRMC) method to evaluate the electron spectrum which can be used as a phase space input for others simulation programs. Such technique uses probability distributions for electron histories previously simulated in spheres (called kugels). These probabilities are used to sample the primary electron final state, as well as the creation secondary electrons and photons. We have compared the MRMC electron spectra simulated in homogeneous phantom against the Geant4 spectra. The results showed an agreement better than 6% in the spectra peak energies and that MRMC code is up to 12 time faster than Geant4 simulations

Application of solid-phase micro extraction for the determination of pesticides in vegetable samples by gas chromatography with an electron capture detector

International Nuclear Information System (INIS)

Chai, Mee Kin; Tan, Guan Huat; Kumari, Asha

2008-01-01

A solid-phase micro extraction (SPME) method has been developed for the determination of 9 pesticides in 2 vegetables -cucumber and tomato - samples, based on direct immersion mode and subsequent desorption into the injection port of a gas chromatograph with an electron capture detector (GC-ECD). The main factors affecting the SPME process such as extraction time and temperature, desorption time and temperature, the effect of salt addition and fiber depth into the liner were studied and optimized. The analytical procedure proposed consisted of a 30 minute ultrasonic extraction of the target compounds from 1.0 g vegetable samples with 5 mL of distilled water. Then, the samples were filtered and topped up with distilled water to 10 mL. The analytes in this aqueous extract were extracted for 15 minutes with a 100 μm thickness polydimethylsiloxane SPME fiber. Relative standard deviations for triplicate analyses of samples were less than 10 %. The recoveries of the pesticides studied in cucumber and tomato ranged from 52 % to 82 % and the RSD were below 10 %. Therefore, the proposed method is applicable in the analysis of pesticides in vegetable matrices. SPME has been shown to be a simple extraction technique, which has a number of advantages such as solvent free extraction, simplicity and compatibility with the chromatographic analytical system. (author)

Non- chemical methods of seed treatment for control of seed- borne pathogens on vegetables

NARCIS (Netherlands)

Amein, T.; Wright, S.A.I.; Wickstrom, M.; Schmitt, A.; Koch, E.; Wolf, van der J.M.; Groot, S.P.C.; Werner, S.; Jahn, M.

2006-01-01

The aim of EU-project "Seed Treatments for Organic Vegetable Production" (STOVE) was to evaluate non-chemical methods for control of seed-borne pathogens in organic vegetable production. Physical (hot air, hot water and electron) and biologi-cal (microorganisms and different agents of natural

Neurophysiological and behavioural responses to music therapy in vegetative and minimally conscious states

Directory of Open Access Journals (Sweden)

Julian eO'Kelly

2013-12-01

Full Text Available Assessment of awareness for those with disorders of consciousness (DOC is a challenging undertaking, due to the complex presentation of the population, where misdiagnosis rates remain high. Music therapy may be effective in the assessment and rehabilitation with this population due to effects of musical stimuli on arousal, attention and emotion, irrespective of verbal or motor deficits, however, an evidence base is lacking. To address this, a neurophysiological and behavioural study was undertaken comparing EEG, heart rate variability, respiration and behavioural responses of 20 healthy subjects with 21 individuals in vegetative or minimally conscious states (VS or MCS. Subjects were presented with live preferred music and improvised music entrained to respiration (i.e., music therapy procedures, recordings of disliked music, white noise and silence. ANOVA tests indicated a range of significant responses (p ≤ 0.05 across healthy subjects corresponding to arousal and attention in response to preferred music including concurrent increases in respiration rate with globally enhanced EEG power spectra responses across frequency bandwidths. Whilst physiological responses were heterogeneous across patients, significant post hoc EEG amplitude increases for stimuli associated with preferred music were found for frontal midline theta in 6 VS and 4 MCS subjects, and frontal alpha in 3 VS and 4 MCS subjects (p = 0.05 - 0.0001. Furthermore, behavioural data showed a significantly increased blink rate for preferred music (p = 0.029 across the VS cohort. Two VS cases are presented with concurrent changes (p ≤ 0.05 across measures indicative of discriminatory responses to both music therapy procedures. A MCS case study highlights how more sensitive selective attention may distinguish MCS from VS. Further investigation is warranted to explore the use of music therapy for prognostic indicators, and its potential to support neuroplasticity in rehabilitation

Simulating sub-Milankovitch climate variations associated with vegetation dynamics

Directory of Open Access Journals (Sweden)

E. Tuenter

2007-01-01

Full Text Available Climate variability at sub-Milankovitch periods (between 2 and 15 kyr is studied in a set of transient simulations with a coupled atmosphere/ocean/vegetation model of intermediate complexity (CLIMBER-2. Focus is on the region influenced by the African and Asian summer monsoon. Pronounced variations at periods of about 10 kyr (Asia and Africa and about 5 kyr (Asia are found in the monsoonal runoff in response to the precessional forcing. In the model this is due to the following mechanism. For low summer insolation (precession maximum precipitation is low and desert expands at the expense of grass, while for high insolation (precession minimum precipitation is high and the tree fraction increases also reducing the grass fraction. This induces sub-Milankovitch variations in the grass fraction and associated variations in the water holding capacity of the soil. The runoff does not exhibit sub-Milankovitch variability when vegetation is kept fixed. High-latitude vegetation also exhibits sub-Milankovitch variability under both obliquity and precessional forcing. We thus hypothesize that sub-Milankovitch variability can occur due to the dynamic response of the vegetation. However, this mechanism should be further tested with more sophisticated climate/vegetation models.

Phenological response of vegetation to upstream river flow in the Heihe Rive basin by time series analysis of MODIS data

Directory of Open Access Journals (Sweden)

L. Jia

2011-03-01

Full Text Available Liquid and solid precipitation is abundant in the high elevation, upper reach of the Heihe River basin in northwestern China. The development of modern irrigation schemes in the middle reach of the basin is taking up an increasing share of fresh water resources, endangering the oasis and traditional irrigation systems in the lower reach. In this study, the response of vegetation in the Ejina Oasis in the lower reach of the Heihe River to the water yield of the upper catchment was analyzed by time series analysis of monthly observations of precipitation in the upper and lower catchment, river streamflow downstream of the modern irrigation schemes and satellite observations of vegetation index. Firstly, remotely sensed NDVI data acquired by Terra-MODIS are used to monitor the vegetation dynamic for a seven years period between 2000 and 2006. Due to cloud-contamination, atmospheric influence and different solar and viewing angles, however, the quality and consistence of time series of remotely sensed NDVI data are degraded. A Fourier Transform method – the Harmonic Analysis of Time Series (HANTS algorithm – is used to reconstruct cloud- and noise-free NDVI time series data from the Terra-MODIS NDVI dataset. Modification is made on HANTS by adding additional parameters to deal with large data gaps in yearly time series in combination with a Temporal-Similarity-Statistics (TSS method developed in this study to seek for initial values for the large gap periods. Secondly, the same Fourier Transform method is used to model time series of the vegetation phenology. The reconstructed cloud-free NDVI time series data are used to study the relationship between the water availability (i.e. the local precipitation and upstream water yield and the evolution of vegetation conditions in Ejina Oasis from 2000 to 2006. Anomalies in precipitation, streamflow, and vegetation index are detected by comparing each year with the average year. The results showed that

Vegetation response to soil salinity and waterlogging in three saltmarsh hydrosequences through macronutrients distribution

Science.gov (United States)

Ferronato, Chiara; Speranza, Maria; Ferroni, Lucia; Buscaroli, Alessandro; Vianello, Gilmo; Vittori Antisari, Livia

2018-01-01

Saltmarshes consist of soil hydrosequences, where the complex interactions between water tide fluctuations, soil physicochemical properties and plant colonization contribute to the triggering of the pedogenetic processes and consequently to the stability of the saltmarsh edges. In this study, the composition and richness of the vegetation cover were investigated along soil transects in three different saltmarshes. With the aim to investigate the response of the vegetation to the soil hydroperiod and its influence on the availability of soil nutrients, plant and soil samples were collected in four representative sites on each saltmarsh transect (hydrosequence). Among the different species of saltmarshes, L. vulgare and S. europaea colonized intertidal areas, where an accumulation of nutrients (Ca, K, P, S and Na) and organic C and total N (OC and TN, respectively) was found. These intertidal areas are the "critical transition zones", which drive the transition between the terrestrial and the aquatic systems along the increase of soil salinity and water saturation. Among the different element cycles analysed in the soil-plant system, the analysis of the Na and S dynamic, through both bioconcentration and translocation indexes, explains the different adaptation mechanisms to different salinity and waterlogging stressors. The limiting of the species areal was generally associated firstly with a decrease in their Na and S bioconcentration factor and, to a lesser extent, with the increase in their Na and S translocation.

Response and Resiliency of Wildlife and Vegetation to Large-Scale Wildfires and Climate Change in the North Cascades

Science.gov (United States)

Bartowitz, K.; Morrison, P.; Romain-Bondi, K.; Smith, C. W.; Warne, L.; McGill, D.

2016-12-01

Changing climatic patterns have affected the western US in a variety of ways: decreases in precipitation and snowpack, earlier spring snowmelt, and increased lightning strikes have created a drier, more fire-prone system, despite variability in these characteristics. Wildfires are a natural phenomenon, but have been suppressed for much of the past century. Effects of this evolving fire regime on native vegetation and wildlife are not well understood. Increased frequency and intensity of fires coupled with subsequent drought and extreme heat may inhibit or alter recovery of native ecosystems. We are currently investigating how a mega-fire has affected presence of western gray squirrels (Sciurus griseus, WGS) in the North Cascades, and the mortality, survival, and recovery of vegetation following these fires and extreme drought. The Methow Valley in WA experienced a record-breaking wildfire in 2014, which disturbed nearly 50% of priority habitat of the North Cascades population of WGS. WGS were studied at the same pre and post-fire plots. WGS were present at over half of the post-burn plots (58%). There was a significant difference in the number of WGS hair samples collected in different levels of remaining vegetation: the most in moderate, few in low, and none in high. Vegetation recovery was assessed through field data, and a chronosequence of satellite images and aerial photography. 75% of the 2014 fire burned non-forested vegetation. Ponderosa pine forests comprised the rest. The forests experienced about 70% initial mortality. Recovery of the forest appears slower than in the shrub-steppe. First year seedling survival was poor due to an extremely hot, dry summer, while second year survival appears higher due to a cool, moist spring and summer. One year after a large, multi-severity fire we found WGS may be more resilient to disturbance such as fires than previously thought. Future studies of WGS will help elucidate long-term response to large-scale fires, and

Consumption of fruit and vegetables and risk of frailty: a dose-response analysis of 3 prospective cohorts of community-dwelling older adults.

Science.gov (United States)

García-Esquinas, Esther; Rahi, Berna; Peres, Karine; Colpo, Marco; Dartigues, Jean-François; Bandinelli, Stefania; Feart, Catherine; Rodríguez-Artalejo, Fernando

2016-07-01

Consuming fruit and vegetables (FVs) may protect against frailty, but to our knowledge no study has yet assessed their prospective dose-response relation. We sought to examine the dose-response association between FV consumption and the risk of frailty in older adults. Data were taken from 3 independent cohorts of community-dwelling older adults: the Seniors-ENRICA (Study on Nutrition and Cardiovascular Risk Factors in Spain) cohort (n = 1872), Three-City (3C) Bordeaux cohort (n = 581), and integrated multidisciplinary approach cohort (n = 473). Baseline food consumption was assessed with a validated computerized diet history (Seniors-ENRICA) or with a food-frequency questionnaire (3C Bordeaux and AMI). In all cohorts, incident frailty was assessed with the use of the Fried criteria. Results across cohorts were pooled with the use of a random-effects model. During a mean 2.5-y follow-up, 300 incident frailty cases occurred. Fully adjusted models showed that the pooled ORs (95% CIs) of incident frailty comparing participants who consumed 1, 2, or ≥3 portions of fruit/d to those with no consumption were, respectively, 0.59 (0.27, 0.90), 0.58 (0.29, 0.86), and 0.48 (0.20, 0.75), with a P-trend of 0.04. The corresponding values for vegetables were 0.69 (0.42, 0.97), 0.56 (0.35, 0.77), and 0.52 (0.13, 0.92), with a P-trend consumption of fruit and risk of exhaustion, low physical activity, and slow walking speed, whereas the consumption of vegetables was associated with a decreased risk of exhaustion and unintentional weight loss. Among community-dwelling older adults, FV consumption was associated with a lower short-term risk of frailty in a dose-response manner, and the strongest association was obtained with 3 portions of fruit/d and 2 portions of vegetables/d. © 2016 American Society for Nutrition.

Vegetation Response to Climate Change in the Southern Part of Qinghai-Tibet Plateau at Basinal Scale

Science.gov (United States)

Liu, X.; Liu, C.; Kang, Q.; Yin, B.

2018-04-01

Global climate change has significantly affected vegetation variation in the third-polar region of the world - the Qinghai-Tibet Plateau. As one of the most important indicators of vegetation variation (growth, coverage and tempo-spatial change), the Normalized Difference Vegetation Index (NDVI) is widely employed to study the response of vegetation to climate change. However, a long-term series analysis cannot be achieved because a single data source is constrained by time sequence. Therefore, a new framework was presented in this paper to extend the product series of monthly NDVI, taking as an example the Yarlung Zangbo River Basin, one of the most important river basins in the Qinghai-Tibet Plateau. NDVI products were acquired from two public sources: Global Inventory Modeling and Mapping Studies (GIMMS) Advanced Very High Resolution Radiometer (AVHRR) and Moderate-Resolution Imaging spectroradiometer (MODIS). After having been extended using the new framework, the new time series of NDVI covers a 384 months period (1982-2013), 84 months longer than previous time series of NDVI product, greatly facilitating NDVI related scientific research. In the new framework, the Gauss Filtering Method was employed to filter out noise in the NDVI product. Next, the standard method was introduced to enhance the comparability of the two data sources, and a pixel-based regression method was used to construct NDVI-extending models with one pixel after another. The extended series of NDVI fit well with original AVHRR-NDVI. With the extended time-series, temporal trends and spatial heterogeneity of NDVI in the study area were studied. Principal influencing factors on NDVI were further determined. The monthly NDVI is highly correlated with air temperature and precipitation in terms of climatic change wherein the spatially averaged NDVI slightly increases in the summer and has increased in temperature and decreased in precipitation in the 32 years period. The spatial heterogeneity of

Varying responses of vegetation activity to climate changes on the Tibetan Plateau grassland.

Science.gov (United States)

Cong, Nan; Shen, Miaogen; Yang, Wei; Yang, Zhiyong; Zhang, Gengxin; Piao, Shilong

2017-08-01

Vegetation activity on the Tibetan Plateau grassland has been substantially enhanced as a result of climate change, as revealed by satellite observations of vegetation greenness (i.e., the normalized difference vegetation index, NDVI). However, little is known about the temporal variations in the relationships between NDVI and temperature and precipitation, and understanding this is essential for predicting how future climate change would affect vegetation activity. Using NDVI data and meteorological records from 1982 to 2011, we found that the inter-annual partial correlation coefficient between growing season (May-September) NDVI and temperature (R NDVI-T ) in a 15-year moving window for alpine meadow showed little change, likely caused by the increasing R NDVI-T in spring (May-June) and autumn (September) and decreasing R NDVI-T in summer (July-August). Growing season R NDVI-T for alpine steppe increased slightly, mainly due to increasing R NDVI-T in spring and autumn. The partial correlation coefficient between growing season NDVI and precipitation (R NDVI-P ) for alpine meadow increased slightly, mainly in spring and summer, and R NDVI-P for alpine steppe increased, mainly in spring. Moreover, R NDVI-T for the growing season was significantly higher in those 15-year windows with more precipitation for alpine steppe. R NDVI-P for the growing season was significantly higher in those 15-year windows with higher temperature, and this tendency was stronger for alpine meadow than for alpine steppe. These results indicate that the impact of warming on vegetation activity of Tibetan Plateau grassland is more positive (or less negative) during periods with more precipitation and that the impact of increasing precipitation is more positive (or less negative) during periods with higher temperature. Such positive effects of the interactions between temperature and precipitation indicate that the projected warmer and wetter future climate will enhance vegetation activity

Response of custom-developed radiochromic dye films after electron irradiation

International Nuclear Information System (INIS)

Vargas-Aburto, C.; Uribe, R.M.; McLauglin, W.L.; Dick, C.E.

1995-01-01

Radiochromic dye (RD) films with varying formulations have been produced in this laboratory and are being used to aid in the determination of both the absorbed dose in irradiated test materials as well as the spatial homogeneity of the electron beam used to perform the irradiations. Specifically, these films have been used during the irradiation of both photovoltaic (solar cells) and liquid crystal-based devices (light valves). However, the optical response of RD films is known to be affected by post-irradiation conditions, such as the storage time and temperature, among others. This work represents a study of the time-dependence of the response of the custom-developed RD films. The change in response has been studied for every formulation, as a function of two different post-irradiation storage temperatures (23 degrees C and 45 degrees C) for a period of six months. Results show that significant changes in the response of these films can be observed even after this extended period. These results are compared with those obtained by other authors on similar films subjected to both electron and gamma ( 60 Co) radiation

Vegetation Carbon Storage, Spatial Patterns and Response to Altitude in Lancang River Basin, Southwest China

Directory of Open Access Journals (Sweden)

Long Chen

2016-01-01

Full Text Available Vegetation plays a very important role of carbon (C sinks in the global C cycle. With its complex terrain and diverse vegetation types, the Lancang River Basin (LRB of southwest China has huge C storage capacity. Therefore, understanding the spatial variations and controlling mechanisms of vegetation C storage is important to understand the regional C cycle. In this study, data from a forest inventory and field plots were used to estimate and map vegetation C storage distribution in the LRB, to qualify the quantitative relationships between vegetation C density and altitude at sublot and township scale, and a linear model or polynomial model was used to identify the relationship between C density and altitude at two spatial scales and two statistical scales. The results showed that a total of 300.32 Tg C was stored in the LRB, an important C sink in China. The majority of C storage was contributed by forests, notably oaks. The vegetation C storage exhibited nonlinear variation with latitudinal gradients. Altitude had tremendous influences on spatial patterns of vegetation C storage of three geomorphological types in the LRB. C storage decreased with increasing altitude at both town and sublot scales in the flat river valley (FRV region and the mid-low mountains gorge (MMG region, and first increased then decreased in the alpine gorge (AG region. This revealed that, in southwest China, altitude changes the latitudinal patterns of vegetation C storage; especially in the AG area, C density in the mid-altitude (3100 m area was higher than that of adjacent areas.

Blue Water Trade-Offs With Vegetation in a CO2-Enriched Climate

Science.gov (United States)

Mankin, Justin S.; Seager, Richard; Smerdon, Jason E.; Cook, Benjamin I.; Williams, A. Park; Horton, Radley M.

2018-04-01

Present and future freshwater availability and drought risks are physically tied to the responses of surface vegetation to increasing CO2. A single-model large ensemble identifies the occurrence of colocated warming- and CO2-induced leaf area index increases with summer soil moisture declines. This pattern of "greening" and "drying," which occurs over 42% of global vegetated land area, is largely attributable to changes in the partitioning of precipitation at the land surface away from runoff and toward terrestrial vegetation ecosystems. Changes in runoff and ecosystem partitioning are inversely related, with changes in runoff partitioning being governed by changes in precipitation (mean and extremes) and ecosystem partitioning being governed by ecosystem water use and surface resistance to evapotranspiration (ET). Projections show that warming-influenced and CO2-enriched terrestrial vegetation ecosystems use water that historically would have been partitioned to runoff over 48% of global vegetated land areas, largely in Western North America, the Amazon, and Europe, many of the same regions with colocated greening and drying. These results have implications for how water available for people will change in response to anthropogenic warming and raise important questions about model representations of vegetation water responses to high CO2.

Electron response and e/h ratio of ATLAS barrel hadron prototype calorimeter

International Nuclear Information System (INIS)

Budagov, Yu.A.; Vinogradov, V.B.; Arkadov, V.V.; Karapetyan, G.V.

1995-01-01

The detailed information about electron response, electron energy resolution and e/h ratio as a function of incident energy E, impact point Z and incidence angle Θ of ATLAS iron-scintillator hadron prototype calorimeter with longitudinal tile configuration is presented. These results are based on electron and pion beams data of E=20, 50, 100, 150, 300 GeV at Θ=10 deg, 20 deg, 30 deg, which were obtained during test beam period in July 1995. The obtained calibration constant is used for muon response converting from pC to GeV. The results are compared with existing experimental data and with some Monte Carlo calculations. For some E, Θ, Z values the compensation (e/h=1) is observed. 23 refs., 18 figs., 9 tabs

Compositional stability of boreal understorey vegetation after overstorey harvesting across a riparian ecotone

Science.gov (United States)

Rebecca L. MacDonald; Han Y.H. Chen; Samuel F. Bartels; Brian J. Palik; Ellie E. Prepas; Frank Gilliam

2015-01-01

Questions: Understanding factors that contribute to the stability of an ecosystem following harvesting is central to predicting responses of boreal ecosystems to increasing human disturbances.While the response of understorey vegetation to harvesting is well understood for upland sites, little is known about compositional stability of riparian understorey vegetation....

Vegetation dynamic characteristics and its responses to climate change in Jinghe River watershed of Loess Plateau, China

Science.gov (United States)

Chang, F.; Liu, W.; Zhou, H.; Ning, T.; Wang, Y.

2017-12-01

The Jinghe River is a second-order tributary of the Yellow River, and located in the middle-south part of the Loess Plateau. The watershed area is 45421km², with the mean annual precipitation (P) being about 508mm and aridity index 2.09. For a long time, soil and water loss in this watershed is severe, resulting in very fragile ecological environment. The GIMMS-normalized vegetation index NDVI is used to reflect condition of vegetation cover, and P and Penman potential evapotranspiration (ET) to represent climate water and heat conditions. The annual actual ET is estimated as the difference between P and runoff (ignoring the change of watershed water storage during each hydrological year, May to April of the following year). These concepts were introduced to discuss the dynamic characteristics of vegetation cover and its response to climate change. Results showed that the mean annual NDVI value was 0.51, showing a stable increasing trend from 2000 with an annual increasing rate of 8.7×10¯³. This result is consistent with the implementation of the project that converts farmland to forests and grassland and has achieved remarkable success in the Loess Plateau since 1999. It also indicates that the positive impact of human activity has been strengthened under the background of climate change. From 1982 to 2012, the annual actual ET was 464mm, accounting for 93.6% of annual P over the same period. The NDVI value of main growing season (5-9 months) is significantly correlated with annual P and annual humid index (ratio of annual P to annual potential ET). Vegetation water consumption is the main part of land surface ET, and the relationship between annual actual ET and NDVI value over the same period is also significant. The NDVI value, P and potential ET variation varied substantially within the Jinghe River watershed, and their relationships in different regions at an inter-annual scale are different. Currently, we are investigating the influence of the changes in

Influence of γ ionizing radiation on anti-oxidative effect of vegetables polyphenolic parts

International Nuclear Information System (INIS)

Stuyck, S.; Connaulte, J.; Lesgards, G.; Prost, M.; Raffi, J.

1998-01-01

Ionizing radiation of vegetables is a cleaning up and preservation physical treatment which consists in submitting them to γ radiation, X radiation or electrons beam. This study deals with the influence of γ radiation on anti-oxidative effect of vegetables polyphenolic parts. In that purpose, we use a simple biological test based on erythrocytes hemolysis. (authors)

Simulating vegetation response to climate change in the Blue Mountains with MC2 dynamic global vegetation model

Directory of Open Access Journals (Sweden)

John B. Kim

2018-04-01

Full Text Available Warming temperatures are projected to greatly alter many forests in the Pacific Northwest. MC2 is a dynamic global vegetation model, a climate-aware, process-based, and gridded vegetation model. We calibrated and ran MC2 simulations for the Blue Mountains Ecoregion, Oregon, USA, at 30 arc-second spatial resolution. We calibrated MC2 using the best available spatial datasets from land managers. We ran future simulations using climate projections from four global circulation models (GCM under representative concentration pathway 8.5. Under this scenario, forest productivity is projected to increase as the growing season lengthens, and fire occurrence is projected to increase steeply throughout the century, with burned area peaking early- to mid-century. Subalpine forests are projected to disappear, and the coniferous forests to contract by 32.8%. Large portions of the dry and mesic forests are projected to convert to woodlands, unless precipitation were to increase. Low levels of change are projected for the Umatilla National Forest consistently across the four GCM’s. For the Wallowa-Whitman and the Malheur National Forest, forest conversions are projected to vary more across the four GCM-based simulations, reflecting high levels of uncertainty arising from climate. For simulations based on three of the four GCMs, sharply increased fire activity results in decreases in forest carbon stocks by the mid-century, and the fire activity catalyzes widespread biome shift across the study area. We document the full cycle of a structured approach to calibrating and running MC2 for transparency and to serve as a template for applications of MC2. Keywords: Climate change, Regional change, Simulation, Calibration, Forests, Fire, Dynamic global vegetation model

The Impact of CO2-Driven Vegetation Changes on Wildfire Risk

Science.gov (United States)

Skinner, C. B.; Poulsen, C. J.

2017-12-01

While wildfires are a key component of natural ecological restoration and succession, they also pose tremendous risks to human life, health, and property. Wildfire frequency is expected to increase in many regions as the radiative effects of elevated CO2 drive warmer surface air temperatures, earlier spring snow melt, and more frequent meteorological drought. However, high CO2 concentrations will also directly impact vegetation growth and physiology, potentially altering wildfire characteristics through changes in fuel amount and surface hydrology. Depending on the biome and time of year, these vegetation-driven responses may mitigate or enhance radiative-driven wildfire changes. In this study, we use a suite of earth system models from the Coupled Model Intercomparison Project 5 with active biogeophysics and biogeochemistry to understand how the vegetation response to high CO2 (CO2 quadrupling) contributes to future changes in wildfire risk across the globe. Across the models, projected CO2 fertilization enhances aboveground biomass (about a 30% leaf area index (LAI) increase averaged across the globe) during the spring and summer months, increasing the availability of wildfire fuel across all biomes. Despite greater LAI, models robustly project widespread reductions in summer season transpiration (about -15% averaged across the globe) in response to reduced stomatal conductance from CO2 physiological forcing. Reduced transpiration warms summer season near surface temperatures and lowers relative humidity across vegetated regions of the mid-to-high latitudes, heightening the risk of wildfire occurrence. However, as transpiration goes down in response to greater plant water use efficiency, a larger fraction of soil water remains in the soil, potentially halting the spread of wildfires in some regions. Given the myriad ways in which the vegetation response to CO2 may alter wildfire risk, and the robustness of the responses across models, an explicit simulation of

Hydrologic responses to restored wildfire regimes revealed by soil moisture-vegetation relationships

Science.gov (United States)

Boisramé, Gabrielle; Thompson, Sally; Stephens, Scott

2018-02-01

Many forested mountain watersheds worldwide evolved with frequent fire, which Twentieth Century fire suppression activities eliminated, resulting in unnaturally dense forests with high water demand. Restoration of pre-suppression forest composition and structure through a variety of management activities could improve forest resilience and water yields. This study explores the potential for "managed wildfire", whereby naturally ignited fires are allowed to burn, to alter the water balance. Interest in this type of managed wildfire is increasing, yet its long-term effects on water balance are uncertain. We use soil moisture as a spatially-distributed hydrologic indicator to assess the influence of vegetation, fire history and landscape position on water availability in the Illilouette Creek Basin in Yosemite National Park. Over 6000 manual surface soil moisture measurements were made over a period of three years, and supplemented with continuous soil moisture measurements over the top 1m of soil in three sites. Random forest and linear mixed effects models showed a dominant effect of vegetation type and history of vegetation change on measured soil moisture. Contemporary and historical vegetation maps were used to upscale the soil moisture observations to the basin and infer soil moisture under fire-suppressed conditions. Little change in basin-averaged soil moisture was inferred due to managed wildfire, but the results indicated that large localized increases in soil moisture had occurred, which could have important impacts on local ecology or downstream flows.

Impact of Waste Materials and Organic Amendments on Soil Properties and Vegetative Performance

Directory of Open Access Journals (Sweden)

Steven L. McGeehan

2012-01-01

Full Text Available Waste materials, and materials derived from wastes, possess many characteristics that can improve soil fertility and enhance crop performance. These materials can be particularly useful as amendments to severely degraded soils associated with mining activities. This study evaluated biosolids, composts, log yard wastes, and two organic soil treatments for improved soil fertility and vegetative performance using side-by-side comparisons. Each plot was seeded with a standardized seed mix and evaluated for a series of soil chemical and physical parameters, total vegetation response, species diversity, ecological plant response, and invasion indices. All treatments were successful at improving soil fertility and promoting a self-sustaining vegetative cover. The level of available nitrogen had a strong impact on vegetative coverage, species distribution, and extent of unseeded vegetation. For example, high nitrogen treatments promoted a grass-dominated (low forb plant community with a low content of unseeded vegetation. In contrast, low nitrogen treatments promoted a more balanced plant community with a mixture of grass and forb species and greater susceptibility to unseeded vegetation establishment.

Review article: Vegetative growth, reproduction, browse production ...

African Journals Online (AJOL)

Vegetative growth, reproduction, browse production and response to tree clearing of ... water stress, soil nutrient availability, carbohydrate reserves, plant hormones, ... animal-plant interactions) of woody plants in various savanna ecosystems.

Increasing biological diversity in a dynamic vegetation model and consequences for simulated response to climate change

Science.gov (United States)

Keribin, R. M.; Friend, A. D.; Purves, D.; Smith, M. J.

2013-12-01

Vegetation, from tropical rainforests to the tundra, is the basis of the world food chain but is also a key component of the Earth system, with biophysical and biogeochemical impacts on the global climate, and Dynamic Global Vegetation Models (DGVMs) are an important integrative tool for understanding its responses to climate change. DGVMs up to now have treated only a small number of plant types representing broad divisions in vegetation worldwide (e.g. trees and grasses, broadleaf and needleleaf, deciduousness), but these categories ignore most of the variation that exists between plant species and between individuals within a species. Research in community ecology makes it clear however that these variations can affect large-scale ecosystem properties such as productivity and resilience to environmental changes. The current challenge is for DGVMs to account for fine-grained variations between plants and a few such models are being developed using newly-available plant trait databases such as the TRY database and insights from community ecology such as habitat filtering. Hybrid is an individual-based DGVM, first published in 1993, that models plant physiology in a mechanistic way. We modified Hybrid 8, the latest version of the model which uses surface physics taken from the GISS ModelE GCM, to include a mechanistic gap-model component with individual-based variation in tree wood density. This key plant trait is known to be strongly correlated with a trade-off between growth and mortality in the majority of forests worldwide, which allows for otherwise-similar individuals to have different life-history strategies. We investigate how the inclusion of continuous variation in wood density into the model affects the ecosystem's transient dynamics under climate change.

Potential Arctic tundra vegetation shifts in response to changing temperature, precipitation and permafrost thaw

NARCIS (Netherlands)

Kolk, van der Henk-Jan; Heijmans, M.M.P.D.; Huissteden, van J.; Pullens, J.W.M.; Berendse, F.

2016-01-01

Over the past decades, vegetation and climate have changed significantly in the Arctic. Deciduous shrub cover is often assumed to expand in tundra landscapes, but more frequent abrupt permafrost thaw resulting in formation of thaw ponds could lead to vegetation shifts towards graminoid-dominated

A Monte Carlo/response surface strategy for sensitivity analysis: application to a dynamic model of vegetative plant growth

Science.gov (United States)

Lim, J. T.; Gold, H. J.; Wilkerson, G. G.; Raper, C. D. Jr; Raper CD, J. r. (Principal Investigator)

1989-01-01

We describe the application of a strategy for conducting a sensitivity analysis for a complex dynamic model. The procedure involves preliminary screening of parameter sensitivities by numerical estimation of linear sensitivity coefficients, followed by generation of a response surface based on Monte Carlo simulation. Application is to a physiological model of the vegetative growth of soybean plants. The analysis provides insights as to the relative importance of certain physiological processes in controlling plant growth. Advantages and disadvantages of the strategy are discussed.

Map of mixed prairie grassland vegetation, Rocky Flats, Colorado

Energy Technology Data Exchange (ETDEWEB)

Clark, S J.V.; Webber, P J; Komarkova, V; Weber, W A

1980-01-01

A color vegetation map at the scale of 1:12,000 of the area surrounding the Rocky Flats, Rockwell International Plant near Boulder, Colorado, provides a permanent record of baseline data which can be used to monitor changes in both vegetation and environment and thus to contribute to future land management and land-use policies. Sixteen mapping units based on species composition were identified, and characterized by two 10-m/sup 2/ vegetation stands each. These were grouped into prairie, pasture, and valley side on the basis of their species composition. Both the mapping units and these major groups were later confirmed by agglomerative clustering analysis of the 32 vegetation stands on the basis of species composition. A modified Bray and Curtis ordination was used to determine the environmental factor complexes controlling the distribution of vegetation at Rocky flats. Recommendations are made for future policies of environmental management and predictions of the response to environmental change of the present vegetation at the Rocky Flats site.

Vegetation anomalies caused by antecedent precipitation in most of the world

Science.gov (United States)

Papagiannopoulou, C.; Miralles, D. G.; Dorigo, W. A.; Verhoest, N. E. C.; Depoorter, M.; Waegeman, W.

2017-07-01

Quantifying environmental controls on vegetation is critical to predict the net effect of climate change on global ecosystems and the subsequent feedback on climate. Following a non-linear Granger causality framework based on a random forest predictive model, we exploit the current wealth of multi-decadal satellite data records to uncover the main drivers of monthly vegetation variability at the global scale. Results indicate that water availability is the most dominant factor driving vegetation globally: about 61% of the vegetated surface was primarily water-limited during 1981-2010. This included semiarid climates but also transitional ecoregions. Intra-annually, temperature controls Northern Hemisphere deciduous forests during the growing season, while antecedent precipitation largely dominates vegetation dynamics during the senescence period. The uncovered dependency of global vegetation on water availability is substantially larger than previously reported. This is owed to the ability of the framework to (1) disentangle the co-linearities between radiation/temperature and precipitation, and (2) quantify non-linear impacts of climate on vegetation. Our results reveal a prolonged effect of precipitation anomalies in dry regions: due to the long memory of soil moisture and the cumulative, non-linear, response of vegetation, water-limited regions show sensitivity to the values of precipitation occurring three months earlier. Meanwhile, the impacts of temperature and radiation anomalies are more immediate and dissipate shortly, pointing to a higher resilience of vegetation to these anomalies. Despite being infrequent by definition, hydro-climatic extremes are responsible for up to 10% of the vegetation variability during the 1981-2010 period in certain areas, particularly in water-limited ecosystems. Our approach is a first step towards a quantitative comparison of the resistance and resilience signature of different ecosystems, and can be used to benchmark Earth

Vegetation response to climate change : implications for Canada's conservation lands

Energy Technology Data Exchange (ETDEWEB)

Scott, D. [Environment Canada, Ottawa, ON (Canada). Adaptation and Impact Research Group; Lemieux, C. [Waterloo Univ., ON (Canada). Dept. of Geography

2003-05-01

Studies have shown that Canada's national parks are vulnerable to the impacts of climate change. A wide range of biophysical climate change impacts could affect the integrity of conservation lands in each region of Canada. This report examines the potential impact of climate change on landscape alterations and vegetation distribution in Canada's wide network of conservation lands. It also presents several ways to integrate climate change into existing conservation policy and adaptation strategies. Canada's conservation lands include provincial parks, migratory bird sanctuaries, national wildlife areas and wildlife protected areas. This is the first study to examine biome changes by applying an equilibrium Global Vegetation Model (GVM) to Canada's network of national park systems. Some of the policy and planning challenges posed by changes in landscape level vegetation were also addressed. The report indicates that in terms of potential changes to the biome classification of Canada's national forests, more northern biomes are projected to decrease. These northern biomes include the tundra, taiga and boreal conifer forests. 56 refs., 8 tabs., 6 figs.

Electronic response and longitudinal phonons of a charge-density-wave distorted linear chain

International Nuclear Information System (INIS)

Giuliani, G.

1978-01-01

The longitudinal-phonon spectrum of an incommensurate charge-density-wave distorted linear chain at T = 0 K are calculated. This is done by direct numerical evaluation of the full static-electronic-response matrix. The electronic band structure assumed for this purpose is that of a mean-field theory 1-D Peierls insulator. The present results show how, within this simplified, but self-consistent picture, the phase and amplitude modes connect to, and interact with, the ordinary longitudinal-phonon branch. Effects due to our inclusion of (0,2ksub(F)) scattering along with the usual (-2ksub(F), 2ksub(F)) are also pointed out. An alternative approximate expression for the 1-D electronic-response matrix is also given. (author)

Plant functional diversity affects climate-vegetation interaction

Science.gov (United States)

Groner, Vivienne P.; Raddatz, Thomas; Reick, Christian H.; Claussen, Martin

2018-04-01

We present how variations in plant functional diversity affect climate-vegetation interaction towards the end of the African Humid Period (AHP) in coupled land-atmosphere simulations using the Max Planck Institute Earth system model (MPI-ESM). In experiments with AHP boundary conditions, the extent of the green Sahara varies considerably with changes in plant functional diversity. Differences in vegetation cover extent and plant functional type (PFT) composition translate into significantly different land surface parameters, water cycling, and surface energy budgets. These changes have not only regional consequences but considerably alter large-scale atmospheric circulation patterns and the position of the tropical rain belt. Towards the end of the AHP, simulations with the standard PFT set in MPI-ESM depict a gradual decrease of precipitation and vegetation cover over time, while simulations with modified PFT composition show either a sharp decline of both variables or an even slower retreat. Thus, not the quantitative but the qualitative PFT composition determines climate-vegetation interaction and the climate-vegetation system response to external forcing. The sensitivity of simulated system states to changes in PFT composition raises the question how realistically Earth system models can actually represent climate-vegetation interaction, considering the poor representation of plant diversity in the current generation of land surface models.

RESPONSE OF RIPARIAN VEGETATION IN AUSTRALIA"S LARGEST RIVER BASIN TO INTER AND INTRA-ANNUAL CLIMATE VARIABILITY AND FLOODING AS QUANTIFIED WITH LANDSAT AND MODIS

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M. Broich

2016-06-01

Full Text Available Australia is a continent subject to high rainfall variability, which has major influences on runoff and vegetation dynamics. However, the resulting spatial-temporal pattern of flooding and its influence on riparian vegetation has not been quantified in a spatially explicit way. Here we focused on the floodplains of the entire Murray-Darling Basin (MDB, an area that covers over 1M km2, as a case study. The MDB is the country’s primary agricultural area with scarce water resources subject to competing demands and impacted by climate change and more recently by the Millennium Drought (1999–2009. Riparian vegetation in the MDB floodplain suffered extensive decline providing a dramatic degradation of riparian vegetation. We quantified the spatial-temporal impact of rainfall, temperature and flooding patters on vegetation dynamics at the subcontinental to local scales and across inter to intra-annual time scales based on three decades of Landsat (25k images, Bureau of Meteorology data and one decade of MODIS data. Vegetation response varied in space and time and with vegetation types, densities and location relative to areas frequently flooded. Vegetation degradation trends were observed over riparian forests and woodlands in areas where flooding regimes have changed to less frequent and smaller inundation extents. Conversely, herbaceous vegetation phenology followed primarily a ‘boom’ and ‘bust’ cycle, related to inter-annual rainfall variability. Spatial patters of vegetation degradation changed along the N-S rainfall gradient but flooding regimes and vegetation degradation patterns also varied at finer scale, highlighting the importance of a spatially explicit, internally consistent analysis and setting the stage for investigating further cross-scale relationships. Results are of interest for land and water management decisions. The approach developed here can be applied to other areas globally such as the Nile river basin and

Fire regimes and vegetation responses in two Mediterranean-climate regions

Science.gov (United States)

Montenegro, G.; Ginocchio, R.; Segura, A.; Keely, J.E.; Gomez, M.

2004-01-01

Wildfires resulting from thunderstorms are common in some Mediterranean-climate regions, such as southern California, and have played an important role in the ecology and evolution of the flora. Mediterranean-climate regions are major centers for human population and thus anthropogenic impacts on fire regimes may have important consequences on these plant formations. However, changes in fire regimes may have different impacts on Mediterranean type-ecosystems depending on the capability of plants to respond to such perturbations. Therefore, we compare here fire regimes and vegetation responses of two Mediterranean-climate regions which differ in wildfire regimes and history of human occupation, the central zone of Chile (matorral) and the southern area of California in United States (chaparral). In Chile almost all fires result from anthropogenic activities, whereas lightning fires resulting from thunderstorms are frequent in California. In both regions fires are more frequent in summer, due to high accumulation of dry plant biomass for ignition. Humans have markedly increased fires frequency both in the matorral and chaparral, but extent of burned areas has remained unaltered, probably due to better fire suppression actions and a decline in the built-up of dry plant fuel associated to increased landscape fragmentation with less flammable agricultural and urban developments. As expected, post-fire plant regeneration responses differs between the matorral and chaparral due to differences in the importance of wildfires as a natural evolutionary force in the system. Plants from the chaparral show a broader range of post-fire regeneration responses than the matorral, from basal resprouting, to lignotuber resprouting, and to fire-stimulated germination and flowering with fire-specific clues such as heat shock, chemicals from smoke or charred wood. Plants from the matorral have some resprouting capabilities after fire, but these probably evolved from other environmental

Predicting the effect of fire on large-scale vegetation patterns in North America.

Science.gov (United States)

Donald McKenzie; David L. Peterson; Ernesto. Alvarado

1996-01-01

Changes in fire regimes are expected across North America in response to anticipated global climatic changes. Potential changes in large-scale vegetation patterns are predicted as a result of altered fire frequencies. A new vegetation classification was developed by condensing Kuchler potential natural vegetation types into aggregated types that are relatively...

Quantifying the Impacts of Environmental Factors on Vegetation Dynamics over Climatic and Management Gradients of Central Asia

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Olena Dubovyk

2016-07-01

Full Text Available Currently there is a lack of quantitative information regarding the driving factors of vegetation dynamics in post-Soviet Central Asia. Insufficient knowledge also exists concerning vegetation variability across sub-humid to arid climatic gradients as well as vegetation response to different land uses, from natural rangelands to intensively irrigated croplands. In this study, we analyzed the environmental drivers of vegetation dynamics in five Central Asian countries by coupling key vegetation parameter “overall greenness” derived from Moderate Resolution Imaging Spectroradiometer (MODIS Normalized Difference Vegetation Index (NDVI time series data, with its possible factors across various management and climatic gradients. We developed nine generalized least-squares random effect (GLS-RE models to analyze the relative impact of environmental factors on vegetation dynamics. The obtained results quantitatively indicated the extensive control of climatic factors on managed and unmanaged vegetation cover across Central Asia. The most diverse vegetation dynamics response to climatic variables was observed for “intensively managed irrigated croplands”. Almost no differences in response to these variables were detected for managed non-irrigated vegetation and unmanaged (natural vegetation across all countries. Natural vegetation and rainfed non-irrigated crop dynamics were principally associated with temperature and precipitation parameters. Variables related to temperature had the greatest relative effect on irrigated croplands and on vegetation cover within the mountainous zone. Further research should focus on incorporating the socio-economic factors discussed here in a similar analysis.

Linear-response theory of Coulomb drag in coupled electron systems

DEFF Research Database (Denmark)

Flensberg, Karsten; Hu, Ben Yu-Kuang; Jauho, Antti-Pekka

1995-01-01

We report a fully microscopic theory for the transconductivity, or, equivalently, the momentum transfer rate, of Coulomb coupled electron systems. We use the Kubo linear-response formalism and our main formal result expresses the transconductivity in terms of two fluctuation diagrams, which...

Snow effects on alpine vegetation in the Qinghai-Tibetan Plateau

Science.gov (United States)

Wang, Kun; Zhang, Li; Qiu, Yubao; Ji, Lei; Tian, Feng; Wang, Cuizhen; Wang, Zhiyong

2013-01-01

Understanding the relationships between snow and vegetation is important for interpretation of the responses of alpine ecosystems to climate changes. The Qinghai-Tibetan Plateau is regarded as an ideal area due to its undisturbed features with low population and relatively high snow cover. We used 500 m Moderate Resolution Imaging Spectroradiometer (MODIS) datasets during 2001–2010 to examine the snow–vegetation relationships, specifically, (1) the influence of snow melting date on vegetation green-up date and (2) the effects of snow cover duration on vegetation greenness. The results showed that the alpine vegetation responded strongly to snow phenology (i.e., snow melting date and snow cover duration) over large areas of the Qinghai-Tibetan Plateau. Snow melting date and vegetation green-up date were significantly correlated (p growth was influenced by different seasonal snow cover durations (SCDs) in different regions. Generally, the December–February and March–May SCDs played a significantly role in vegetation growth, both positively and negatively, depending on different water source regions. Snow's positive impact on vegetation was larger than the negative impact.

Predicting landscape vegetation dynamics using state-and-transition simulation models

Science.gov (United States)

Colin J. Daniel; Leonardo. Frid

2012-01-01

This paper outlines how state-and-transition simulation models (STSMs) can be used to project changes in vegetation over time across a landscape. STSMs are stochastic, empirical simulation models that use an adapted Markov chain approach to predict how vegetation will transition between states over time, typically in response to interactions between succession,...

VEGETATION RESPONSE TO CLIMATE CHANGE IN THE SOUTHERN PART OF QINGHAI-TIBET PLATEAU AT BASINAL SCALE

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X. Liu

2018-04-01

Full Text Available Global climate change has significantly affected vegetation variation in the third-polar region of the world – the Qinghai-Tibet Plateau. As one of the most important indicators of vegetation variation (growth, coverage and tempo-spatial change, the Normalized Difference Vegetation Index (NDVI is widely employed to study the response of vegetation to climate change. However, a long-term series analysis cannot be achieved because a single data source is constrained by time sequence. Therefore, a new framework was presented in this paper to extend the product series of monthly NDVI, taking as an example the Yarlung Zangbo River Basin, one of the most important river basins in the Qinghai-Tibet Plateau. NDVI products were acquired from two public sources: Global Inventory Modeling and Mapping Studies (GIMMS Advanced Very High Resolution Radiometer (AVHRR and Moderate-Resolution Imaging spectroradiometer (MODIS. After having been extended using the new framework, the new time series of NDVI covers a 384 months period (1982–2013, 84 months longer than previous time series of NDVI product, greatly facilitating NDVI related scientific research. In the new framework, the Gauss Filtering Method was employed to filter out noise in the NDVI product. Next, the standard method was introduced to enhance the comparability of the two data sources, and a pixel-based regression method was used to construct NDVI-extending models with one pixel after another. The extended series of NDVI fit well with original AVHRR-NDVI. With the extended time-series, temporal trends and spatial heterogeneity of NDVI in the study area were studied. Principal influencing factors on NDVI were further determined. The monthly NDVI is highly correlated with air temperature and precipitation in terms of climatic change wherein the spatially averaged NDVI slightly increases in the summer and has increased in temperature and decreased in precipitation in the 32 years period. The

Exploiting differential vegetation phenology for satellite-based mapping of semiarid grass vegetation in the southwestern United States and northern Mexico

Science.gov (United States)

Dye, Dennis G.; Middleton, Barry R.; Vogel, John M.; Wu, Zhuoting; Velasco, Miguel G.

2016-01-01

We developed and evaluated a methodology for subpixel discrimination and large-area mapping of the perennial warm-season (C4) grass component of vegetation cover in mixed-composition landscapes of the southwestern United States and northern Mexico. We describe the methodology within a general, conceptual framework that we identify as the differential vegetation phenology (DVP) paradigm. We introduce a DVP index, the Normalized Difference Phenometric Index (NDPI) that provides vegetation type-specific information at the subpixel scale by exploiting differential patterns of vegetation phenology detectable in time-series spectral vegetation index (VI) data from multispectral land imagers. We used modified soil-adjusted vegetation index (MSAVI2) data from Landsat to develop the NDPI, and MSAVI2 data from MODIS to compare its performance relative to one alternate DVP metric (difference of spring average MSAVI2 and summer maximum MSAVI2), and two simple, conventional VI metrics (summer average MSAVI2, summer maximum MSAVI2). The NDPI in a scaled form (NDPIs) performed best in predicting variation in perennial C4 grass cover as estimated from landscape photographs at 92 sites (R2 = 0.76, p landscapes of the Southwest, and potentially for monitoring of its response to drought, climate change, grazing and other factors, including land management. With appropriate adjustments, the method could potentially be used for subpixel discrimination and mapping of grass or other vegetation types in other regions where the vegetation components of the landscape exhibit contrasting seasonal patterns of phenology.

Enhancement of vegetation-rainfall feedbacks on the Australian summer monsoon by the Madden-Julian Oscillation

Science.gov (United States)

Notaro, Michael

2018-01-01

A regional climate modeling analysis of the Australian monsoon system reveals a substantial modulation of vegetation-rainfall feedbacks by the Madden Julian Oscillation (MJO), both of which operate at similar sub-seasonal time scales, as evidence that the intensity of land-atmosphere interactions is sensitive to the background atmospheric state. Based on ensemble experiments with imposed modification of northern Australian leaf area index (LAI), the atmospheric responses to LAI anomalies are composited for negative and positive modes of the propagating MJO. In the regional climate model (RCM), northern Australian vegetation feedbacks are characterized by evapotranspiration (ET)-driven rainfall responses, with the moisture feedback mechanism dominating over albedo and roughness feedback mechanisms. During November-April, both Tropical Rainfall Measuring Mission and RCM data reveal MJO's pronounced influence on rainfall patterns across northern Australia, tropical Indian Ocean, Timor Sea, Arafura Sea, and Gulf of Carpentaria, with the MJO dominating over vegetation feedbacks in terms of regulating monsoon rainfall variability. Convectively-active MJO phases support an enhancement of positive vegetation feedbacks on monsoon rainfall. While the MJO imposes minimal regulation of ET responses to LAI anomalies, the vegetation feedback-induced responses in precipitable water, cloud water, and rainfall are greatly enhanced during convectively-active MJO phases over northern Australia, which are characterized by intense low-level convergence and efficient precipitable water conversion. The sub-seasonal response of vegetation-rainfall feedback intensity to the MJO is complex, with significant enhancement of rainfall responses to LAI anomalies in February during convectively-active MJO phases compared to minimal modulation by the MJO during prior and subsequent calendar months.

Forest vegetation simulation tools and forest health assessment

Science.gov (United States)

Richard M. Teck; Melody Steele

1995-01-01

A Stand Hazard Rating System for Central ldaho forests has been incorporated into the Central ldaho Prognosis variant of the Forest Vegetation Simulator to evaluate how insects, disease and fire hazards within the Deadwood River Drainage change over time. A custom interface, BOISE.COMPUTE.PR, has been developed so hazard ratings can be electronically downloaded...

Lipid production in aquatic plant Azolla at vegetative and reproductive stages and in response to abiotic stress.

Science.gov (United States)

Miranda, Ana F; Liu, Zhiqian; Rochfort, Simone; Mouradov, Aidyn

2018-03-01

The aquatic plant Azolla became increasingly popular as bioenergy feedstock because of its high growth rate, production of biomass with high levels of biofuel-producing molecules and ability to grow on marginal lands. In this study, we analysed the contribution of all organs of Azolla to the total yield of lipids at vegetative and reproductive stages and in response to stress. Triacylglycerol-containing lipid droplets were detected in all (vegetative and reproductive) organs with the highest level in the male microsporocarps and microspores. As a result, significantly higher total yields of lipids were detected in Azolla filiculoides and Azolla pinnata at the reproductive stage. Starving changed the yield and composition of the fatty acid as a result of re-direction of carbon flow from fatty acid to anthocyanin pathways. The composition of lipids, in regard the length and degree of unsaturation of fatty acids, in Azolla meets most of the important requirements for biodiesel standards. The ability of Azolla to grow on wastewaters, along with their high productivity rate, makes it an attractive feedstock for the production of biofuels. Copyright © 2018 Elsevier Masson SAS. All rights reserved.

Response of soft winter wheat (Triticum aestivum L. to longtime enforced dormancy and time of spring vegetation recommencing

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В. С. Хахула

2013-05-01

Full Text Available The article highlights the results of studying the soft winter wheat response to the duration of enforced winter dormancy and the time of vegetation recommencing, their impact on growth, development and the survival of the crops. It is found that the impact of those factors in the conditions of central Forest-Steppe of Ukraine is essential, which is to be taken into consideration when scheduling the measures of spring and summer care over the cultivated crops, in particular, where the spring extra nutrition takes place, pesticides and growth regulators are applied, the spaced planting resowing or partial resowing issues are to be settled down. The ecological effect of spring vegetation recommencing dates does not expose annually, therefore it is not always possible to predict the plant development type, but it is possible, nevertheless, to influence the processes of growth, development and survival of plants throughout spring-summer period and the development of their production capacity by means of introducing the intense technologies, optimization of mineral nutrition and the use of plant growth regulators, protection from rogues, diseases, pests.

Implications of introducing realistic fire response traits in a Dynamic Global Vegetation Model

Science.gov (United States)

Kelley, D.; Harrison, S. P.; Prentice, I. C.

2013-12-01

the next growing season, while regenerating from seed at 10% the rate of non-resprouters. Tests of LPX-Mv1 for Australia - a continent with a wide range of fire-adapted ecosystems - show that it produces a 33% improvement in the simulation of vegetation composition compared to the previous version of the model, with more realistic vegetation transitions from forests to woodland/savanna. It also produces a 19% improvement in the simulation of burnt area compared to the original model. Resprouting PFTs dominate tropical and temperate areas where the climate is semi-humid but are not common in very dry or very wet areas. Comparison with site-based observations of the abundance of resprouters indicate this is realistic. Ecosystems dominated by resprouters in the simulations recover to pre-fire levels of biomass within 5-7 years, much faster than ecosystems dominated by non-resprouters; again this is confirmed by our analyses of the observations. Simulations of the response to projected future climate change show that the incorporation of adaptive bark thickness and of resprouting has a significant effect on terrestrial carbon stocks in fire-affected areas.

Short-term responses of decomposers and vegetation to stump removal

Energy Technology Data Exchange (ETDEWEB)

Kataja-aho, S.

2011-07-01

Stump removal has become a common practice to produce raw material for bioenergy production. It was hypothesized that stump removal is an extensive and more intense disturbance for forest ecosystems (soil decomposer organisms and vegetation) compared to traditional site preparation after clear cutting. Therefore, the effects of stump harvesting on forest soil decomposers, vegetation and nutrient dynamics in undisturbed patches of the forest soil and in exposed mineral soil were compared to the effects of the traditional site preparation method, mounding. Nematodes and enchytraeids were the only decomposer groups that were directly affected (negatively) by the stump removal. Regardless of the treatment, the abundances of most of the decomposer groups were consistently lower in the exposed mineral soil than in the intact forest soil. There was 2-3 times more exposed mineral soil in stump removal sites compared to mounding sites. When this was taken into account, the decomposer community was negatively affected by the stump removal at the forest stand level. However, the greater soil disturbance at the stump harvesting sites enhanced CO{sub 2} production, net nitrogen mineralisation and nitrification. The increased N availability and the changes in microclimate due to the disturbance probably explained the vegetation increase at the stump harvested sites. Planted Norway spruce seedlings grew faster during the first two growing periods at the stump removal sites than at the mounding sites. The seedlings had high and similar ectomycorrhizal colonization rate in both treatments. In the short-term, it is probably not the resources removed in the stumps themselves, but the degree and amount of soil disturbance during the stump harvesting procedure that affects the decomposer community and its function in the clear-felled stands. (orig.)

Ecosystem Evapotranspiration as a Response to Climate and Vegetation Coverage Changes in Northwest Yunnan, China.

Science.gov (United States)

Yang, Hao; Luo, Peng; Wang, Jun; Mou, Chengxiang; Mo, Li; Wang, Zhiyuan; Fu, Yao; Lin, Honghui; Yang, Yongping; Bhatta, Laxmi Dutt

2015-01-01

Climate and human-driven changes play an important role in regional droughts. Northwest Yunnan Province is a key region for biodiversity conservation in China, and it has experienced severe droughts since the beginning of this century; however, the extent of the contributions from climate and human-driven changes remains unclear. We calculated the ecosystem evapotranspiration (ET) and water yield (WY) of northwest Yunnan Province, China from 2001 to 2013 using meteorological and remote sensing observation data and a Surface Energy Balance System (SEBS) model. Multivariate regression analyses were used to differentiate the contribution of climate and vegetation coverage to ET. The results showed that the annual average vegetation coverage significantly increased over time with a mean of 0.69 in spite of the precipitation fluctuation. Afforestation/reforestation and other management efforts attributed to vegetation coverage increase in NW Yunnan. Both ET and WY considerably fluctuated with the climate factors, which ranged from 623.29 mm to 893.8 mm and -51.88 mm to 384.40 mm over the time period. Spatially, ET in the southeast of NW Yunnan (mainly in Lijiang) increased significantly, which was in line with the spatial trend of vegetation coverage. Multivariate linear regression analysis indicated that climatic factors accounted for 85.18% of the ET variation, while vegetation coverage explained 14.82%. On the other hand, precipitation accounted for 67.5% of the WY. We conclude that the continuous droughts in northwest Yunnan were primarily climatically driven; however, man-made land cover and vegetation changes also increased the vulnerability of local populations to drought. Because of the high proportion of the water yield consumed for subsistence and poor infrastructure for water management, local populations have been highly vulnerable to climate drought conditions. We suggest that conservation of native vegetation and development of water

Satellite Monitoring of Vegetation Response to Precipitation and Dust Storm Outbreaks in Gobi Desert Regions

Directory of Open Access Journals (Sweden)

Yuki Sofue

2018-02-01

Full Text Available Recently, droughts have become widespread in the Northern Hemisphere, including in Mongolia. The ground surface condition, particularly vegetation coverage, affects the occurrence of dust storms. The main sources of dust storms in the Asian region are the Taklimakan and Mongolian Gobi desert regions. In these regions, precipitation is one of the most important factors for growth of plants especially in arid and semi-arid land. The purpose of this study is to clarify the relationship between precipitation and vegetation cover dynamics over 29 years in the Gobi region. We compared the patterns between precipitation and Normalized Difference Vegetation Index (NDVI for a period of 29 years. The precipitation and vegetation datasets were examined to investigate the trends during 1985–2013. Cross correlation analysis between the precipitation and the NDVI anomalies was performed. Data analysis showed that the variations of NDVI anomalies in the east region correspond well with the precipitation anomalies during this period. However, in the southwest region of the Gobi region, the NDVI had decreased regardless of the precipitation amount, especially since 2010. This result showed that vegetation in this region was more degraded than in the other areas.

Comparing the response of birds and butterflies to vegetation-based mountain ecotones using boundary detection approaches.

Science.gov (United States)

Kent, Rafi; Levanoni, Oded; Banker, Eran; Pe'er, Guy; Kark, Salit

2013-01-01

Mountains provide an opportunity to examine changes in biodiversity across environmental gradients and areas of transition (ecotones). Mountain ecotones separate vegetation belts. Here, we aimed to examine whether transition areas for birds and butterflies spatially correspond with ecotones between three previously described altitudinal vegetation belts on Mt. Hermon, northern Israel. These include the Mediterranean Maquis, xero-montane open forest and Tragacanthic mountain steppe vegetation belts. We sampled the abundance of bird and butterfly species in 34 sampling locations along an elevational gradient between 500 and 2200 m. We applied wombling, a boundary-detection technique, which detects rapid changes in a continuous variable, in order to locate the transition areas for bird and butterfly communities and compare the location of these areas with the location of vegetation belts as described in earlier studies of Mt. Hermon. We found some correspondence between the areas of transition of both bird and butterfly communities and the ecotones between vegetation belts. For birds and butterflies, important transitions occurred at the lower vegetation ecotone between Mediterranean maquis and the xero-montane open forest vegetation belts, and between the xero-montane open forest and the mountain steppe Tragacanthic belts. While patterns of species turnover with elevation were similar for birds and butterflies, the change in species richness and diversity with elevation differed substantially between the two taxa. Birds and butterflies responded quite similarly to the elevational gradient and to the shift between vegetation belts in terms of species turnover rates. While the mechanisms generating these patterns may differ, the resulting areas of peak turnover in species show correspondence among three different taxa (plants, birds and butterflies).

Effect of ballistic electrons on ultrafast thermomechanical responses of a thin metal film

International Nuclear Information System (INIS)

Xiong Qi-lin; Tian Xin

2017-01-01

The ultrafast thermomechanical coupling problem in a thin gold film irradiated by ultrashort laser pulses with different electron ballistic depths is investigated via the ultrafast thermoelasticity model. The solution of the problem is obtained by solving finite element governing equations. The comparison between the results of ultrafast thermomechanical coupling responses with different electron ballistic depths is made to show the ballistic electron effect. It is found that the ballistic electrons have a significant influence on the ultrafast thermomechanical coupling behaviors of the gold thin film and the best laser micromachining results can be achieved by choosing the specific laser technology (large or small ballistic range). In addition, the influence of simplification of the ultrashort laser pulse source on the results is studied, and it is found that the simplification has a great influence on the thermomechanical responses, which implies that care should be taken when the simplified form of the laser source term is applied as the Gaussian heat source. (paper)

VEGETATION MAPPING IN WETLANDS

Directory of Open Access Journals (Sweden)

F. PEDROTTI

2004-01-01

Full Text Available The current work examines the main aspects of wetland vegetation mapping, which can be summarized as analysis of the ecological-vegetational (ecotone gradients; vegetation complexes; relationships between vegetation distribution and geomorphology; vegetation of the hydrographic basin lo which the wetland in question belongs; vegetation monitoring with help of four vegetation maps: phytosociological map of the real and potential vegetation, map of vegetation dynamical tendencies, map of vegetation series.

Canopy Modeling of Aquatic Vegetation: Construction of Submerged Vegetation Index

Science.gov (United States)

Ma, Z.; Zhou, G.

2018-04-01

The unique spectral characteristics of submerged vegetation in wetlands determine that the conventional terrestrial vegetation index cannot be directly employed to species identification and parameter inversion of submerged vegetation. Based on the Aquatic Vegetation Radiative Transfer model (AVRT), this paper attempts to construct an index suitable for submerged vegetation, the model simulated data and a scene of Sentinel-2A image in Taihu Lake, China are utilized for assessing the performance of the newly constructed indices and the existent vegetation indices. The results show that the angle index composed by 525 nm, 555 nm and 670 nm can resist the effects of water columns and is more sensitive to vegetation parameters such as LAI. Furthermore, it makes a well discrimination between submerged vegetation and water bodies in the satellite data. We hope that the new index will provide a theoretical basis for future research.

Excitation energies with linear response density matrix functional theory along the dissociation coordinate of an electron-pair bond in N-electron systems

International Nuclear Information System (INIS)

Meer, R. van; Gritsenko, O. V.; Baerends, E. J.

2014-01-01

Time dependent density matrix functional theory in its adiabatic linear response formulation delivers exact excitation energies ω α and oscillator strengths f α for two-electron systems if extended to the so-called phase including natural orbital (PINO) theory. The Löwdin-Shull expression for the energy of two-electron systems in terms of the natural orbitals and their phases affords in this case an exact phase-including natural orbital functional (PILS), which is non-primitive (contains other than just J and K integrals). In this paper, the extension of the PILS functional to N-electron systems is investigated. With the example of an elementary primitive NO functional (BBC1) it is shown that current density matrix functional theory ground state functionals, which were designed to produce decent approximations to the total energy, fail to deliver a qualitatively correct structure of the (inverse) response function, due to essential deficiencies in the reconstruction of the two-body reduced density matrix (2RDM). We now deduce essential features of an N-electron functional from a wavefunction Ansatz: The extension of the two-electron Löwdin-Shull wavefunction to the N-electron case informs about the phase information. In this paper, applications of this extended Löwdin-Shull (ELS) functional are considered for the simplest case, ELS(1): one (dissociating) two-electron bond in the field of occupied (including core) orbitals. ELS(1) produces high quality ω α (R) curves along the bond dissociation coordinate R for the molecules LiH, Li 2 , and BH with the two outer valence electrons correlated. All of these results indicate that response properties are much more sensitive to deficiencies in the reconstruction of the 2RDM than the ground state energy, since derivatives of the functional with respect to both the NOs and the occupation numbers need to be accurate

Radiation preservation and test marketing of fruits and vegetables

International Nuclear Information System (INIS)

Xu Zhicheng; Cai Dong; He Fuying; Zhao Deyao

1993-01-01

To develop the technology for radiation preservation of fruits and vegetables, many varieties of fruits and vegetables had been researched. Results showed that low dose irradiation is useful to preserve fruits and vegetables. On the basis of research, 1900 tons of garlic, 950 tons onion, 500 tons potatoes, 710 tons apples and 1000 kg litchi had been irradiated on a commercial scale. The quality control standards of irradiated garlic, onion and potato had been established and used for commercial scale irradiation. In order to collect consumers in-store response to irradiated foods, a special counter was set up for selling irradiated apples in Nan Jing Road (W), Shanghai. 634 sheets of consumer in-store response investigation forms have been returned and analysed. These results showed that when consumer understands the benefit of irradiation preservation such as higher quality, greater safety, longer shelf-life, wide product availability, or good prices for value, consumer would willingly buy irradiated food. (author)

Changes in the bacterial number (enterohaemorrhagic E. coli O157:H7, coliforms and SPC) in salted vegetables during storage and by treatment with electron-beam irradiation

International Nuclear Information System (INIS)

Miyahara, Michiko; Miyahara, Makoto

2007-01-01

Enterohaemorrhagic Escherichia coli O157:H7 causes severe illness in humans, especially young children and elder people. Some 2-3% salted vegetables (called Asazuke) contaminated with E. coli O157:H7 have caused food-poisoning and even death. The viability of E. coli O157:H7 in saline water and in salted vegetables was tested. During cold and frozen storage, the apparent decrease in the number of E. coli O157:H7 was not observed. However, electron-beam irradiation (0.534, 1.097 and 2.639 kGy) caused clear decrease in the numbers of E. coli O157:H7 in frozen salted Mizuna. The number of standard plating count (SPC) and coliforms were also counted and compared with the changes in the number of E. coli O157:H7. (author)

Ultimate response time of high electron mobility transistors

International Nuclear Information System (INIS)

Rudin, Sergey; Rupper, Greg; Shur, Michael

2015-01-01

We present theoretical studies of the response time of the two-dimensional gated electron gas to femtosecond pulses. Our hydrodynamic simulations show that the device response to a short pulse or a step-function signal is either smooth or oscillating time-decay at low and high mobility, μ, values, respectively. At small gate voltage swings, U 0  = U g  − U th , where U g is the gate voltage and U th is the threshold voltage, such that μU 0 /L < v s , where L is the channel length and v s is the effective electron saturation velocity, the decay time in the low mobility samples is on the order of L 2 /(μU 0 ), in agreement with the analytical drift model. However, the decay is preceded by a delay time on the order of L/s, where s is the plasma wave velocity. This delay is the ballistic transport signature in collision-dominated devices, which becomes important during very short time periods. In the high mobility devices, the period of the decaying oscillations is on the order of the plasma wave velocity transit time. Our analysis shows that short channel field effect transistors operating in the plasmonic regime can meet the requirements for applications as terahertz detectors, mixers, delay lines, and phase shifters in ultra high-speed wireless communication circuits

Abrupt vegetation transitions characterise long-term Amazonian peatland development

Science.gov (United States)

Roucoux, K. H.; Baker, T. R.; Gosling, W. D.; Honorio Coronado, E.; Jones, T. D.; Lahteenoja, O.; Lawson, I. T.

2012-04-01

woodland with abundant Myrtaceae; (4) Expansion of Mauritia/Mauritiella palm swamp vegetation c. 1000 years ago representing establishment of the present day vegetation community. Our results show that the vegetation at this site has undergone continuous change throughout the period of peat formation. The sequence of vegetation development is not straightforward, being characterised by abrupt transitions between vegetation types and reversals in the apparent trajectory of change. Overall this suggests that the system is highly dynamic on centennial to millennial timescales. This complexity may reflect vegetation responses to a combination of external (physical) and internal (biological) drivers and the presence of thresholds in the system. Future investigations will work towards understanding the processes that drive these vegetation transitions and predicting peatland vegetation responses to future climatic change.

Post-fire vegetation dynamics in Portugal

Science.gov (United States)

Gouveia, C.; Dacamara, C. C.; Trigo, R. M.

2009-04-01

The number of fires and the extent of the burned surface in Mediterranean Europe have increased significantly during the last three decades. This may be due either to modifications in land-use (e.g. land abandonment and fuel accumulation) or to climatic changes (e.g. reduction of fuel humidity), both factors leading to an increase of fire risk and fire spread. As in the Mediterranean ecosystems, fires in Portugal have an intricate effect on vegetation regeneration due to the complexity of landscape structures as well as to the different responses of vegetation to the variety of fire regimes. A thorough evaluation of vegetation recovery after fire events becomes therefore crucial in land management. In the above mentioned context remote sensing plays an important role because of its ability to monitor and characterise post-fire vegetation dynamics. A number of fire recovery studies, based on remote sensing, have been conducted in regions characterised by Mediterranean climates and the use of NDVI to monitor plant regeneration after fire events was successfully tested (Díaz-Delgado et al., 1998). In particular, several studies have shown that rapid regeneration occurs within the first 2 years after the fire occurrences, with distinct recovery rates according to the geographical facing of the slopes (Pausas and Vallejo, 1999). In 2003 Portugal was hit by the most devastating sequence of large fires, responsible by a total burnt area of 450 000 ha (including 280 000 ha of forest), representing about 5% of the Portuguese mainland (Trigo et al., 2006). The aim of the present work is to assess and monitor the vegetation behaviour over Portugal following the 2003 fire episodes. For this purpose we have used the regional fields of the Normalized Difference Vegetation Index (NDVI) as obtained from the VEGETATION-SPOT5 instrument, from 1999 to 2008. We developed a methodology to identify large burnt scars in Portugal for the 2003 fire season. The vegetation dynamics was then

Seasat synthetic aperture radar ( SAR) response to lowland vegetation types in eastern Maryland and Virginia.

Science.gov (United States)

Krohn, M.D.; Milton, N.M.; Segal, D.B.

1983-01-01

Examination of Seasat SAR images of eastern Maryland and Virginia reveals botanical distinctions between vegetated lowland areas and adjacent upland areas. Radar returns from the lowland areas can be either brighter or darker than returns from the upland forests. Scattering models and scatterometer measurements predict an increase of 6 dB in backscatter from vegetation over standing water. This agrees with the 30-digital number (DN) increase observed in the digital Seasat data. The density, morphology, and relative geometry of the lowland vegetation with respect to standing water can all affect the strength of the return L band signal.-from Authors

Effects of N on plant response to heat-wave: a field study with prairie vegetation.

Science.gov (United States)

Wang, Dan; Heckathorn, Scott A; Mainali, Kumar; Hamilton, E William

2008-11-01

More intense, more frequent, and longer heat-waves are expected in the future due to global warming, which could have dramatic ecological impacts. Increasing nitrogen (N) availability and its dynamics will likely impact plant responses to heat stress and carbon (C) sequestration in terrestrial ecosystems. This field study examined the effects of N availability on plant response to heat-stress (HS) treatment in naturally-occurring vegetation. HS (5 d at ambient or 40.5 degrees C) and N treatments (+/-N) were applied to 16 1 m(2) plots in restored prairie vegetation dominated by Andropogon gerardii (warm-season C4 grass) and Solidago canadensis (warm-season C3 forb). Before, during, and after HS, air, canopy, and soil temperature were monitored; net CO2 assimilation (P(n)), quantum yield of photosystem II (Phi(PSII)), stomatal conductance (g(s)), and leaf water potential (Psi(w)) of the dominant species and soil respiration (R(soil)) of each plot were measured daily during HS. One week after HS, plots were harvested, and C% and N% were determined for rhizosphere and bulk soil, and above-ground tissue (green/senescent leaf, stem, and flower). Photosynthetic N-use efficiency (PNUE) and N resorption rate (NRR) were calculated. HS decreased P(n), g(s), Psi(w), and PNUE for both species, and +N treatment generally increased these variables (+/-HS), but often slowed their post-HS recovery. Aboveground biomass tended to decrease with HS in both species (and for green leaf mass in S. canadensis), but decrease with +N for A. gerardii and increase with +N for S. canadensis. For A. gerardii, HS tended to decrease N% in green tissues with +N, whereas in S. canadensis, HS increased N% in green leaves. Added N decreased NRR for A. gerardii and HS increased NRR for S. canadensis. These results suggest that heat waves, though transient, could have significant effects on plants, communities, and ecosystem N cycling, and N can influence the effect of heat waves.

Vegetation dynamics and dynamic vegetation science

NARCIS (Netherlands)

Van der Maarel, E

1996-01-01

his contribution presents a review of the development of the study of vegetation dynamics since 1979, in the framework of a jubilee meeting on progress in the study of vegetation. However, an exhaustive review is both impossible and unnecessary. It is impossible within the few pages available

Vegetation survey: a new focus for Applied Vegetation Science

NARCIS (Netherlands)

Chytry, M.; Schaminee, J.H.J.; Schwabe, A.

2011-01-01

Vegetation survey is an important research agenda in vegetation science. It defines vegetation types and helps understand differences among them, which is essential for both basic ecological research and applications in biodiversity conservation and environmental monitoring. In this editorial, we

Biodiversity of Terrestrial Vegetation during Past Warm Periods

Science.gov (United States)

Davies-Barnard, T.; Valdes, P. J.; Ridgwell, A.

2016-12-01

Previous modelling studies of vegetation have generally used a small number of plant functional types to understand how the terrestrial biosphere responds to climate changes. Whilst being useful for understanding first order climate feedbacks, this climate-envelope approach makes a lot of assumptions about past vegetation being very similar to modern. A trait-based method has the advantage for paleo modelling in that there are substantially less assumptions made. In a novel use of the trait-based dynamic vegetation model JeDi, forced with output from climate model HadCM3, we explore past biodiversity and vegetation carbon changes. We use JeDi to model an optimal 2000 combinations of fifteen different traits to enable assessment of the overall level of biodiversity as well as individual growth strategies. We assess the vegetation shifts and biodiversity changes in past greenhouse periods to better understand the impact on the terrestrial biosphere. This work provides original insights into the response of vegetation and terrestrial carbon to climate and hydrological changes in high carbon dioxide climates over time, including during the Late Permian and Cretaceous. We evaluate how the location of biodiversity hotspots and species richness in past greenhouse climates is different to the present day.

The response of Arctic vegetation to the summer climate: relation between shrub cover, NDVI, surface albedo and temperature

Energy Technology Data Exchange (ETDEWEB)

Blok, Daan; Heijmans, Monique M P D; Berendse, Frank [Nature Conservation and Plant Ecology Group, Wageningen University, PO Box 47, 6700 AA, Wageningen (Netherlands); Schaepman-Strub, Gabriela [Institute of Evolutionary Biology and Environmental Studies, University of Zuerich, Winterthurerstrasse 190, 8057 Zuerich (Switzerland); Bartholomeus, Harm [Centre for Geo-Information, Wageningen University, PO Box 47, 6700 AA, Wageningen (Netherlands); Maximov, Trofim C, E-mail: daan.blok@wur.nl [Biological Problems of the Cryolithozone, Russian Academy of Sciences, Siberian Division, 41, Lenin Prospekt, Yakutsk, The Republic of Sakha, Yakutia 677980 (Russian Federation)

2011-07-15

Recently observed Arctic greening trends from normalized difference vegetation index (NDVI) data suggest that shrub growth is increasing in response to increasing summer temperature. An increase in shrub cover is expected to decrease summer albedo and thus positively feed back to climate warming. However, it is unknown how albedo and NDVI are affected by shrub cover and inter-annual variations in the summer climate. Here, we examine the relationship between deciduous shrub fractional cover, NDVI and albedo using field data collected at a tundra site in NE Siberia. Field data showed that NDVI increased and albedo decreased with increasing deciduous shrub cover. We then selected four Arctic tundra study areas and compiled annual growing season maximum NDVI and minimum albedo maps from MODIS satellite data (2000-10) and related these satellite products to tundra vegetation types (shrub, graminoid, barren and wetland tundra) and regional summer temperature. We observed that maximum NDVI was greatest in shrub tundra and that inter-annual variation was negatively related to summer minimum albedo but showed no consistent relationship with summer temperature. Shrub tundra showed higher albedo than wetland and barren tundra in all four study areas. These results suggest that a northwards shift of shrub tundra might not lead to a decrease in summer minimum albedo during the snow-free season when replacing wetland tundra. A fully integrative study is however needed to link results from satellite data with in situ observations across the Arctic to test the effect of increasing shrub cover on summer albedo in different tundra vegetation types.

The response of Arctic vegetation to the summer climate: relation between shrub cover, NDVI, surface albedo and temperature

International Nuclear Information System (INIS)

Blok, Daan; Heijmans, Monique M P D; Berendse, Frank; Schaepman-Strub, Gabriela; Bartholomeus, Harm; Maximov, Trofim C

2011-01-01

Recently observed Arctic greening trends from normalized difference vegetation index (NDVI) data suggest that shrub growth is increasing in response to increasing summer temperature. An increase in shrub cover is expected to decrease summer albedo and thus positively feed back to climate warming. However, it is unknown how albedo and NDVI are affected by shrub cover and inter-annual variations in the summer climate. Here, we examine the relationship between deciduous shrub fractional cover, NDVI and albedo using field data collected at a tundra site in NE Siberia. Field data showed that NDVI increased and albedo decreased with increasing deciduous shrub cover. We then selected four Arctic tundra study areas and compiled annual growing season maximum NDVI and minimum albedo maps from MODIS satellite data (2000-10) and related these satellite products to tundra vegetation types (shrub, graminoid, barren and wetland tundra) and regional summer temperature. We observed that maximum NDVI was greatest in shrub tundra and that inter-annual variation was negatively related to summer minimum albedo but showed no consistent relationship with summer temperature. Shrub tundra showed higher albedo than wetland and barren tundra in all four study areas. These results suggest that a northwards shift of shrub tundra might not lead to a decrease in summer minimum albedo during the snow-free season when replacing wetland tundra. A fully integrative study is however needed to link results from satellite data with in situ observations across the Arctic to test the effect of increasing shrub cover on summer albedo in different tundra vegetation types.

Projected future vegetation changes for the northwest United States and southwest Canada at a fine spatial resolution using a dynamic global vegetation model.

Science.gov (United States)

Shafer, Sarah; Bartlein, Patrick J.; Gray, Elizabeth M.; Pelltier, Richard T.

2015-01-01

Future climate change may significantly alter the distributions of many plant taxa. The effects of climate change may be particularly large in mountainous regions where climate can vary significantly with elevation. Understanding potential future vegetation changes in these regions requires methods that can resolve vegetation responses to climate change at fine spatial resolutions. We used LPJ, a dynamic global vegetation model, to assess potential future vegetation changes for a large topographically complex area of the northwest United States and southwest Canada (38.0–58.0°N latitude by 136.6–103.0°W longitude). LPJ is a process-based vegetation model that mechanistically simulates the effect of changing climate and atmospheric CO2 concentrations on vegetation. It was developed and has been mostly applied at spatial resolutions of 10-minutes or coarser. In this study, we used LPJ at a 30-second (~1-km) spatial resolution to simulate potential vegetation changes for 2070–2099. LPJ was run using downscaled future climate simulations from five coupled atmosphere-ocean general circulation models (CCSM3, CGCM3.1(T47), GISS-ER, MIROC3.2(medres), UKMO-HadCM3) produced using the A2 greenhouse gases emissions scenario. Under projected future climate and atmospheric CO2 concentrations, the simulated vegetation changes result in the contraction of alpine, shrub-steppe, and xeric shrub vegetation across the study area and the expansion of woodland and forest vegetation. Large areas of maritime cool forest and cold forest are simulated to persist under projected future conditions. The fine spatial-scale vegetation simulations resolve patterns of vegetation change that are not visible at coarser resolutions and these fine-scale patterns are particularly important for understanding potential future vegetation changes in topographically complex areas.

Recent shifts in Himalayan vegetation activity trends in response to climatic change and environmental drivers

Science.gov (United States)

Mishra, N. B.; Mainali, K. P.

2016-12-01

Climatic changes along with anthropogenic disturbances are causing dramatic ecological impacts in mid to high latitude mountain vegetation including in the Himalayas which are ecologically sensitive environments. Given the challenges associated with in situ vegetation monitoring in the Himalayas, remote sensing based quantification of vegetation dynamics can provide essential ecological information on changes in vegetation activity that may consist of alternative sequence of greening and/or browning periods. This study utilized a trend break analysis procedure for detection of monotonic as well as abrupt (either interruption or reversal) trend changes in smoothed normalized difference vegetation index satellite time-series data over the Himalayas. Overall, trend breaks in vegetation greenness showed high spatio-temporal variability in distribution considering elevation, ecoregion and land cover/use stratifications. Interrupted greening was spatially most dominant in all Himalayan ecoregions followed by abrupt browning. Areas showing trend reversal and monotonic trends appeared minority. Trend type distribution was strongly dependent on elevation as majority of greening (with or without interruption) occurred at lower elevation areas at higher elevation were dominantly. Ecoregion based stratification of trend types highlighted some exception to this elevational dependence as high altitude ecoregions of western Himalayas showed significantly less browning compared to the ecoregions in eastern Himalaya. Land cover/use based analysis of trend distribution showed that interrupted greening was most dominant in closed needleleafed forest following by rainfed cropland and mosaic croplands while interrupted browning most dominant in closed to open herbaceous vegetation found at higher elevation areas followed by closed needleleafed forest and closed to open broad leafed evergreen forests. Spatial analysis of trend break timing showed that for majority of areas experiencing

Ecosystem Evapotranspiration as a Response to Climate and Vegetation Coverage Changes in Northwest Yunnan, China.

Directory of Open Access Journals (Sweden)

Hao Yang

Full Text Available Climate and human-driven changes play an important role in regional droughts. Northwest Yunnan Province is a key region for biodiversity conservation in China, and it has experienced severe droughts since the beginning of this century; however, the extent of the contributions from climate and human-driven changes remains unclear. We calculated the ecosystem evapotranspiration (ET and water yield (WY of northwest Yunnan Province, China from 2001 to 2013 using meteorological and remote sensing observation data and a Surface Energy Balance System (SEBS model. Multivariate regression analyses were used to differentiate the contribution of climate and vegetation coverage to ET. The results showed that the annual average vegetation coverage significantly increased over time with a mean of 0.69 in spite of the precipitation fluctuation. Afforestation/reforestation and other management efforts attributed to vegetation coverage increase in NW Yunnan. Both ET and WY considerably fluctuated with the climate factors, which ranged from 623.29 mm to 893.8 mm and -51.88 mm to 384.40 mm over the time period. Spatially, ET in the southeast of NW Yunnan (mainly in Lijiang increased significantly, which was in line with the spatial trend of vegetation coverage. Multivariate linear regression analysis indicated that climatic factors accounted for 85.18% of the ET variation, while vegetation coverage explained 14.82%. On the other hand, precipitation accounted for 67.5% of the WY. We conclude that the continuous droughts in northwest Yunnan were primarily climatically driven; however, man-made land cover and vegetation changes also increased the vulnerability of local populations to drought. Because of the high proportion of the water yield consumed for subsistence and poor infrastructure for water management, local populations have been highly vulnerable to climate drought conditions. We suggest that conservation of native vegetation and development of water

The impact of spices on vegetable consumption

DEFF Research Database (Denmark)

Li, Zhaoping; Krak, Michael; Zerlin, Alona

2015-01-01

This pilot study was conducted to evaluate the impact of spices added to broccoli, cauliflower, and spinach on amount and rate of vegetable consumption. Twenty overweight subjects who routinely ate less than three daily servings of vegetables were recruited. On six occasions, subjects were assigned...... in random order to eat broccoli, cauliflower, or spinach with or without added spices. Dishes were placed on a modified Universal Eating Monitor (UEM) that recorded rate of eating (g/sec), duration of eating (min) and total amount consumed (g). Total intake and duration of eating were increased...... significantly for broccoli with spices compared to plain broccoli, but there was no significant difference for cauliflower or spinach. No significant differences were noted in any of the visual analog scale (VAS) responses. This study suggests that adding spices may increase vegetable intake, but more studies...

Changes in vegetation structure and aboveground biomass in ...

African Journals Online (AJOL)

Changes in vegetation structure and aboveground biomass in response to traditional rangeland management practices in Borana, southern Ethiopia. ... managed by prescribed fire for five years and grazed only post-fire during dry seasons.

A model for estimating understory vegetation response to fertilization and precipitation in loblolly pine plantations

Science.gov (United States)

Curtis L. VanderSchaaf; Ryan W. McKnight; Thomas R. Fox; H. Lee Allen

2010-01-01

A model form is presented, where the model contains regressors selected for inclusion based on biological rationale, to predict how fertilization, precipitation amounts, and overstory stand density affect understory vegetation biomass. Due to time, economic, and logistic constraints, datasets of large sample sizes generally do not exist for understory vegetation. Thus...

The French, German, and Spanish sound of eating fresh fruits and vegetables.

Science.gov (United States)

Arboleda, Ana M; Arce-Lopera, Carlos

2017-12-01

A set of onomatopoeic expressions for eating fruits and vegetables is compared across subjects whose native language is Spanish, French, or German. Subjects chose the onomatopoeia that best represented the sound of eating a fruit or vegetable (celery, banana, strawberry, passion fruit, mango, apple, orange, and tomato). Results show there are onomatopoeias that have a higher frequency of response in one language compared to the others. Thus, it is possible to assume that depending on the language there is a better way to express haptic and auditory information associated to fruit and vegetable consumption. Moreover, and considering the three languages, results show there are three categories of responses based on the relative strength of the material (strong and medium strength, and soft). Thus, there is some consistency in the onomatopoeias that represent the sound of eating a fruit or a vegetable. To conclude, results differ by language, but they are consistent within a category of sound. Copyright © 2017 Elsevier Ltd. All rights reserved.

Application of a Coupled Vegetation Competition and Groundwater Simulation Model to Study Effects of Sea Level Rise and Storm Surges on Coastal Vegetation

Directory of Open Access Journals (Sweden)

Su Yean Teh

2015-09-01

Full Text Available Global climate change poses challenges to areas such as low-lying coastal zones, where sea level rise (SLR and storm-surge overwash events can have long-term effects on vegetation and on soil and groundwater salinities, posing risks of habitat loss critical to native species. An early warning system is urgently needed to predict and prepare for the consequences of these climate-related impacts on both the short-term dynamics of salinity in the soil and groundwater and the long-term effects on vegetation. For this purpose, the U.S. Geological Survey’s spatially explicit model of vegetation community dynamics along coastal salinity gradients (MANHAM is integrated into the USGS groundwater model (SUTRA to create a coupled hydrology–salinity–vegetation model, MANTRA. In MANTRA, the uptake of water by plants is modeled as a fluid mass sink term. Groundwater salinity, water saturation and vegetation biomass determine the water available for plant transpiration. Formulations and assumptions used in the coupled model are presented. MANTRA is calibrated with salinity data and vegetation pattern for a coastal area of Florida Everglades vulnerable to storm surges. A possible regime shift at that site is investigated by simulating the vegetation responses to climate variability and disturbances, including SLR and storm surges based on empirical information.

Impacts of Climate Change Induced Vegetation Responses on BVOC Emissions from Subarctic Heath Ecosystems

DEFF Research Database (Denmark)

Valolahti, Hanna Maritta

The role of biogenic volatile organic compounds (BVOCs) affecting Earths’ climate system is one of the greatest uncertainties when modelling the global climate change. BVOCs presence in the atmosphere can have both positive and negative climate feedback mechanisms when they involve atmospheric...... chemistry and physics. Vegetation is the main source of BVOCs. Their production is directly linked to temperature and the foliar biomass. On global scale, vegetation in subarctic and arctic regions has been modeled to have only minor contribution to annual total BVOC emissions. In these regions cold...... temperature has been regulating annual plant biomass production, but ongoing global warming is more pronounced in these regions than what the global average is. This may increase the importance of subarctic and arctic vegetation as a source of BVOC emissions in near future. This thesis aims to increase...

Improving simulated long-term responses of vegetation to temperature and precipitation extremes using the ACME land model

Science.gov (United States)

Ricciuto, D. M.; Warren, J.; Guha, A.

2017-12-01

While carbon and energy fluxes in current Earth system models generally have reasonable instantaneous responses to extreme temperature and precipitation events, they often do not adequately represent the long-term impacts of these events. For example, simulated net primary productivity (NPP) may decrease during an extreme heat wave or drought, but may recover rapidly to pre-event levels following the conclusion of the extreme event. However, field measurements indicate that long-lasting damage to leaves and other plant components often occur, potentially affecting the carbon and energy balance for months after the extreme event. The duration and frequency of such extreme conditions is likely to shift in the future, and therefore it is critical for Earth system models to better represent these processes for more accurate predictions of future vegetation productivity and land-atmosphere feedbacks. Here we modify the structure of the Accelerated Climate Model for Energy (ACME) land surface model to represent long-term impacts and test the improved model against observations from experiments that applied extreme conditions in growth chambers. Additionally, we test the model against eddy covariance measurements that followed extreme conditions at selected locations in North America, and against satellite-measured vegetation indices following regional extreme events.

Short-term vegetation response following mechanical control of saltcedar (Tamarix spp.) on the Virgin River, Nevada, USA

Science.gov (United States)

Ostoja, Steven M.; Brooks, Matthew L.; Dudley, Tom; Lee, Steven R.

2014-01-01

Tamarisk (a.k.a. saltcedar, Tamarix spp.) is an invasive plant species that occurs throughout western riparian and wetland ecosystems. It is implicated in alterations of ecosystem structure and function and is the subject of many local control projects, including removal using heavy equipment. We evaluated short-term vegetation responses to mechanical Tamarix spp. removal at sites ranging from 2 to 5 yr post-treatment along the Virgin River in Nevada, USA. Treatments resulted in lower density and cover (but not eradication) of Tamarix spp., increased cover of the native shrub Pluchea sericia (arrow weed), decreased density and cover of all woody species combined, increased density of both native annual forbs and the nonnative annual Salsola tragus (prickly Russian-thistle), and lower density of nonnative annual grasses. The treated plots had lower mean woody species richness, but greater herbaceous species richness and diversity. Among herbaceous species, native taxa increased in richness whereas nonnative species increased in both species richness and diversity. Thus, efforts to remove Tamarix,/i> spp. at the Virgin River reduced vegetative cover contributing to fuel loads and probability of fire, and resulted in positive effects for native plant diversity, with mixed effects on other nonnative species. However, absolute abundances of native species

The Role of Riparian Vegetation in Protecting and Improving Chemical Water Quality in Streams

Science.gov (United States)

Michael G. Dosskey; Philippe Vidon; Noel P. Gurwick; Craig J. Allan; Tim P. Duval; Richard Lowrance

2010-01-01

We review the research literature and summarize the major processes by which riparian vegetation influences chemical water quality in streams, as well as how these processes vary among vegetation types, and discuss how these processes respond to removal and restoration of riparian vegetation and thereby determine the timing and level of response in stream water quality...

Serving vegetables first: A strategy to increase vegetable consumption in elementary school cafeterias.

Science.gov (United States)

Elsbernd, S L; Reicks, M M; Mann, T L; Redden, J P; Mykerezi, E; Vickers, Z M

2016-01-01

Vegetable consumption in the United States is low despite the wealth of evidence that vegetables play an important role in reducing risk of various chronic diseases. Because eating patterns developed in childhood continue through adulthood, we need to form healthy eating habits in children. The objective of this study was to determine if offering vegetables before other meal components would increase the overall consumption of vegetables at school lunch. We served kindergarten through fifth-grade students a small portion (26-33 g) of a raw vegetable (red and yellow bell peppers) while they waited in line to receive the rest of their lunch meal. They then had the options to take more of the bell peppers, a different vegetable, or no vegetable from the lunch line. We measured the amount of each vegetable consumed by each child. Serving vegetables first greatly increased the number of students eating vegetables. On intervention days most of the vegetables consumed came from the vegetables-first portions. Total vegetable intake per student eating lunch was low because most students chose to not eat vegetables, but the intervention significantly increased this value. Serving vegetables first is a viable strategy to increase vegetable consumption in elementary schools. Long-term implementation of this strategy may have an important impact on healthy eating habits, vegetable consumption, and the health consequences of vegetable intake. Copyright © 2015 Elsevier Ltd. All rights reserved.

Electronic response of a photodiode coupled to a boron thin film

Energy Technology Data Exchange (ETDEWEB)

Costa, Priscila; Costa, Fabio E.; Raele, Marcus P.; Zahn, Guilherme S.; Geraldo, Bianca; Vieira Junior, Nilson D.; Samad, Ricardo E.; Genezini, Frederico A., E-mail: priscila3.costa@usp.br, E-mail: fredzini@ipen.br [Instituto de Pesquisas Energéticas e Nucleares (IPEN/CNEN-SP), São Paulo, SP (Brazil)

2017-07-01

A portable thermal neutron detector is proposed in this work using a silicon photodiode coupled to a boron thin film. The aim of this work was to verify the effect in the electronic response of this specific photodiode due to boron deposition, since the direct deposition of boron in the semiconductor surface could affect its electrical properties specifically the p-type layer that affects directly the depletion region of the semiconductor reducing the neutron detector efficiency count. Three boron depositions with different thickness were performed in the photodiode (S3590-09) surface by pulsed laser deposition and the photodiode was characterized, before and after the deposition process, using a radioactive americium source. Energy spectra were used to verify the electronic response of the photodiode, due to the fact that it is possible to relate it to the photopeak pulse height and resolution. Spectra from the photodiode without and with boron film deposition were compared and a standard photodiode (S3590-04) that had the electronic signal conserved was used as reference to the pulse height for electronics adjustments. The photopeak energy resolution for the photodiode without boron layer was 10.26%. For the photodiode with boron deposition at different thicknesses, the resolution was: 7.64 % (0.14 μm), 7.30 % (0.44 μm) and 6.80 % (0.63 μm). From these results it is possible to evaluate that there was not any degradation in the silicon photodiode. (author)

Ion response to relativistic electron bunches in the blowout regime of laser-plasma accelerators.

Science.gov (United States)

Popov, K I; Rozmus, W; Bychenkov, V Yu; Naseri, N; Capjack, C E; Brantov, A V

2010-11-05

The ion response to relativistic electron bunches in the so called bubble or blowout regime of a laser-plasma accelerator is discussed. In response to the strong fields of the accelerated electrons the ions form a central filament along the laser axis that can be compressed to densities 2 orders of magnitude higher than the initial particle density. A theory of the filament formation and a model of ion self-compression are proposed. It is also shown that in the case of a sharp rear plasma-vacuum interface the ions can be accelerated by a combination of three basic mechanisms. The long time ion evolution that results from the strong electrostatic fields of an electron bunch provides a unique diagnostic of laser-plasma accelerators.

A dynamic ecosystem process model for understanding interactions between permafrost thawing and vegetation responses in the arctic

Science.gov (United States)

Xu, C.; Travis, B. J.; Fisher, R. A.; Wilson, C. J.; McDowell, N.

2010-12-01

The arctic is expected to play an important role in the Earth’s future climate due to the large carbon stocks that are stored in permafrost and peatlands, a substantial proportion of which may be released to the atmosphere due to permafrost thawing. There may be positive feedbacks of permafrost thawing on plant growth by releasing stored nitrogen and increasing rooting depth; however, vegetation response to other changing variables such as CO2 and temperature can also modify soil hydrology and energy fluxes, leading to either positive or negative feedbacks on permafrost thawing. Disentangling the interactions between permafrost thawing and vegetation growth is critical for assessing the potential role of arctic regions on current and future global carbon cycling. We have developed a mechanistic, regional, and spatially explicit dynamic ecosystem process model through the integration of a 3-D soil hydrology and biogeochemistry model (Arctic Hydrology, ARCHY) and a dynamic vegetation model (Ecosystem Demography, ED), to quantify the importance of plant-permafrost interactions to soil and plant carbon storage. This model integrates important processes including photosynthesis, transpiration, respiration, 3-D competition for light, 3-D soil hydrology, energy fluxes (ice melting in the soil and solar radiation interception by canopy), nitrogen cycles (microbial decomposition, nitrogen transportation in soil, passive and active nitrogen uptake by plants), species migration, and drought-related mortality. A sensitivity analysis has been implemented to assess the importance of the hydrological cycle, the nitrogen cycle and energy fluxes in regulating the above and below-ground carbon cycles in arctic regions. Our model can fill an important gap between field and global land surface models for assessing plot and regional level hypotheses in the context of global climate.

Modelling post-fire vegetation recovery in Portugal

Science.gov (United States)

Bastos, A.; Gouveia, C. M.; Dacamara, C. C.; Trigo, R. M.

2011-12-01

Wildfires in Mediterranean Europe have been increasing in number and extension over the last decades and constitute one of the major disturbances of these ecosystems. Portugal is the country with more burnt area in the last decade and the years of 2003 and 2005 were particularly devastating, the total burned areas of 425 000 and 338 000 ha being several times higher than the corresponding average. The year of 2005 further coincided with one of the most severe droughts since early 20th century. Due to different responses of vegetation to diverse fire regimes and to the complexity of landscape structures, fires have complex effects on vegetation recovery. Remote sensing has revealed to be a powerful tool in studying vegetation dynamics and in monitoring post-fire vegetation recovery, which is crucial to land-management and to prevent erosion. The main goals of the present work are (i) to assess the accuracy of a vegetation recovery model previously developed by the authors; (ii) to assess the model's performance, namely its sensitivity to initial conditions, to the temporal length of the input dataset and to missing data; (iii) to study vegetation recovery over two selected areas that were affected by two large wildfire events in the fire seasons of 2003 and 2005, respectively. The study relies on monthly values of NDVI over 11 years (1998-2009), at 1 km × 1 km spatial resolution, as obtained by the VEGETATION instrument. According to results from sensitivity analysis, the model is robust and able to provide good estimations of recovery times of vegetation when the regeneration process is regular, even when missing data is present. In respect to the two selected burnt scars, results indicate that fire damage is a determinant factor of regeneration, as less damaged vegetation recovers more rapidly, which is mainly justified by the high coverage of Pinus pinaster over the area, and by the fact that coniferous forests tend to recover slower than transitional woodland

Relationships of body mass index with serum carotenoids, tocopherols and retinol at steady-state and in response to a carotenoid-rich vegetable diet intervention in Filipino schoolchildren.

Science.gov (United States)

Ribaya-Mercado, Judy D; Maramag, Cherry C; Tengco, Lorena W; Blumberg, Jeffrey B; Solon, Florentino S

2008-04-01

In marginally nourished children, information is scarce regarding the circulating concentrations of carotenoids and tocopherols, and physiological factors influencing their circulating levels. We determined the serum concentrations of carotenoids, tocopherols and retinol at steady state and in response to a 9-week vegetable diet intervention in 9-12-year-old girls (n=54) and boys (n=65) in rural Philippines. We determined cross-sectional relationships of BMI (body mass index) with serum micronutrient levels, and whether BMI is a determinant of serum carotenoid responses to the ingestion of carotenoid-rich vegetables. We measured dietary nutrient intakes and assessed inflammation by measurement of serum C-reactive protein levels. The children had low serum concentrations of carotenoids, tocopherols and retinol as compared with published values for similar-aged children in the U.S.A. The low serum retinol levels can be ascribed to inadequate diets and were not the result of confounding due to inflammation. Significant inverse correlations of BMI and serum all-trans-beta-carotene, 13-cis-beta-carotene, alpha-carotene, lutein, zeaxanthin and alpha-tocopherol (but not beta-cryptoxanthin, lycopene and retinol) were observed among girls at baseline. The dietary intervention markedly enhanced the serum concentrations of all carotenoids. Changes in serum all-trans-beta-carotene and alpha-carotene (but not changes in lutein, zeaxanthin and beta-cryptoxanthin) in response to the dietary intervention were inversely associated with BMI in girls and boys. Thus, in Filipino school-aged children, BMI is inversely related to the steady-state serum concentrations of certain carotenoids and vitamin E, but not vitamin A, and is a determinant of serum beta- and alpha-carotene responses, but not xanthophyll responses, to the ingestion of carotenoid-rich vegetable meals.

On the sources of vegetation activity variation, and their relation with water balance in Mexico

Science.gov (United States)

F. Mora; L.R. Iverson

1998-01-01

Natural landscape surface processes are largely controlled by the relationship between climate and vegetation. Water balance integrates the effects of climate on patterns of vegetation distribution and productivity, and for that season, functional relationships can be established using water balance variables as predictors of vegetation response. In this study, we...

Metabolic response of Geobacter sulfurreducens towards electron donor/acceptor variation

Directory of Open Access Journals (Sweden)

Lovley Derek R

2010-11-01

Full Text Available Abstract Background Geobacter sulfurreducens is capable of coupling the complete oxidation of organic compounds to iron reduction. The metabolic response of G. sulfurreducens towards variations in electron donors (acetate, hydrogen and acceptors (Fe(III, fumarate was investigated via 13C-based metabolic flux analysis. We examined the 13C-labeling patterns of proteinogenic amino acids obtained from G. sulfurreducens cultured with 13C-acetate. Results Using 13C-based metabolic flux analysis, we observed that donor and acceptor variations gave rise to differences in gluconeogenetic initiation, tricarboxylic acid cycle activity, and amino acid biosynthesis pathways. Culturing G. sulfurreducens cells with Fe(III as the electron acceptor and acetate as the electron donor resulted in pyruvate as the primary carbon source for gluconeogenesis. When fumarate was provided as the electron acceptor and acetate as the electron donor, the flux analysis suggested that fumarate served as both an electron acceptor and, in conjunction with acetate, a carbon source. Growth on fumarate and acetate resulted in the initiation of gluconeogenesis by phosphoenolpyruvate carboxykinase and a slightly elevated flux through the oxidative tricarboxylic acid cycle as compared to growth with Fe(III as the electron acceptor. In addition, the direction of net flux between acetyl-CoA and pyruvate was reversed during growth on fumarate relative to Fe(III, while growth in the presence of Fe(III and acetate which provided hydrogen as an electron donor, resulted in decreased flux through the tricarboxylic acid cycle. Conclusions We gained detailed insight into the metabolism of G. sulfurreducens cells under various electron donor/acceptor conditions using 13C-based metabolic flux analysis. Our results can be used for the development of G. sulfurreducens as a chassis for a variety of applications including bioremediation and renewable biofuel production.

The fire-vegetation-climate system: how ecology can contribute to earth system science

CSIR Research Space (South Africa)

Archibald, S

2013-05-01

Full Text Available and future state of global vegetation. A key complexity that is currently not well captured by Earth System models is that vegetation is not always deterministically responsive to climate and soils. Feedbacks within the Earth System, top-down controls...

[Responses of vegetation changes to climatic variations in Panxi area based on the MODIS multispectral data].

Science.gov (United States)

Shao, Huai-Yong; Wu, Jin-Hui; Liu, Meng; Yang, Wu-Nian

2014-01-01

It is an important research area to quantitatively studying the relationship between global climatic change and vegetation change based on the remote sensing technology. Panxi area is the ecological barrier of the upper reaches of the Yangtze River, and it is essential for the stability of the ecological environment of Sichuan as well as that of the whole China. The present article analyzes the vegetation change in 2001-2008 and the relationship between vegetation change and climatic variations of Panxi area, based on MODIS multispectral data and meteorological data. The results indicate that NDVI is positively correlated with temperature and precipitation. The precipitation is the major factor that affects the change of vegetation in the Panxi region and the trend of NDVI is similar with autumn precipitation; while at the same time the influence of climate has a one-month-time-lag.

The soil water balance in a mosaic of clumped vegetation

Science.gov (United States)

Pizzolla, Teresa; Manfreda, Salvatore; Caylor, Kelly; Gioia, Andrea; Iacobellis, Vito

2014-05-01

The spatio-temporal distribution of soil moisture influences the plant growth and the distribution of terrestrial vegetation. This effect is more evident in arid and semiarid ecosystems where the interaction between individuals and the water limited conditions play a fundamental role, providing environmental conditions which drive a variety of non-linear ecohydrological response functions (such as transpiration, photosynthesis, leakage). In this context, modeling vegetation patterns at multiple spatial aggregation scales is important to understand how different vegetation structures can modify the soil water distribution and the exchanged fluxes between soil and atmosphere. In the present paper, the effect of different spatial vegetation patterns, under different climatic scenarios, is investigated in a patchy vegetation mosaic generated by a random process of individual tree canopies and their accompanying root system. Vegetation pattern are generated using the mathematical framework proposed by Caylor et al. (2006) characterized by a three dimensional stochastic vegetation structure, based on the density, dispersion, size distribution, and allometry of individuals within a landscape. A Poisson distribution is applied to generate different distribution of individuals paying particular attention on the role of clumping on water distribution dynamics. The soil water balance is evaluated using the analytical expression proposed by Laio et al. (2001) to explore the influence of climate and vegetation patterns on soil water balance steady-state components (such as the average rates of evaporation, the root water uptake and leakage) and on the stress-weighted plant water uptake. Results of numerical simulations show that clumping may be beneficial for water use efficiency at the landscape scale. References Caylor, Kelly K., P. D'Odorico and I. Rodriguez Iturbe: On the ecohydrology of structurally heterogeneous semiarid landscape. Water Resour. Res., 28, W07424, 2006

Trends in global vegetation activity and climatic drivers indicate a decoupled response to climate change

DEFF Research Database (Denmark)

Schut, Antonius G T; Ivits, Eva; Conijn, Jacob G.

2015-01-01

Detailed understanding of a possible decoupling between climatic drivers of plant productivity and the response of ecosystems vegetation is required. We compared trends in six NDVI metrics (1982-2010) derived from the GIMMS3g dataset with modelled biomass productivity and assessed uncertainty...... in trend estimates. Annual total biomass weight (TBW) was calculated with the LINPAC model. Trends were determined using a simple linear regression, a Thiel-Sen medium slope and a piecewise regression (PWR) with two segments. Values of NDVI metrics were related to Net Primary Production (MODIS......-NPP) and TBWper biome and land-use type. The simple linear and Thiel-Sen trends did not differ much whereas PWR increased the fraction of explained variation, depending on the NDVI metric considered. A positive trend in TBW indicating more favorable climatic conditions was found for 24% of pixels on land...

Response of Soil Fungi Community Structure to Salt Vegetation Succession in the Yellow River Delta.

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Wang, Yan-Yun; Guo, Du-Fa

2016-10-01

High-throughput sequencing technology was used to reveal the composition and distribution of fungal community structure in the Yellow River Delta under bare land and four kinds of halophyte vegetation (saline seepweed, Angiospermae, Imperata and Apocynum venetum [A. venetum]). The results showed that the soil quality continuously improved with the succession of salt vegetation types. The soil fungi richness of mild-salt communities (Imperata and A. venetum) was relatively higher, with Shannon index values of 5.21 and 5.84, respectively. The soil fungi richness of severe-salt-tolerant communities (saline seepweed, Angiospermae) was relatively lower, with Shannon index values of 4.64 and 4.66, respectively. The UniFrac metric values ranged from 0.48 to 0.67 when the vegetation was in different succession stages. A total of 60,174 valid sequences were obtained for the five vegetation types, and they were classified into Ascomycota, Basidiomycota, Chytridiomycota, Glomeromycota and Mucoromycotina. Ascomycota had the greatest advantage among plant communities of Imperata and A. venetum, as indicated by relative abundances of 2.69 and 69.97 %, respectively. Basidiomycota had the greatest advantage among mild-salt communities of saline seepweed and Angiospermae, with relative abundances of 9.43 and 6.64 %, respectively. Soil physical and chemical properties were correlated with the distribution of the fungi, and Mucor was significantly correlated with soil moisture (r = 0.985; P Soil quality, salt vegetation and soil fungi were influenced by each other.

The Holocene vegetation history of northern West Jutland

DEFF Research Database (Denmark)

Odgaard, Bent Vad

1994-01-01

. The Holocene history of each lake basin was investigated by mapping of sediment distribution, analysis of loss-on-ignition, coarse inorganic matter, humus content, mineral magnetics, 6°C. pollen and selected other microfossils. These techniques were supplemented by plant macrofossil analysis at one site....... Holocene terrestrial vegetational development was inferred at each site from analyses of pollen and microscopical charred particles. Chronologies were provided by numerous I4C dates. Stratigraphies of wet ground and terrestrial pollen and spore types were zooned by stratigraphically constrained cluster......, the synchronous timing of relatively rapid inferred change in lake and terrestrial vegetation around AD 600 may reflect changes in climate as well as in land-use. Redundancy analysis was used to develop a model between fire intensity (inferred from microscopical charred particles) and vegetational response...

Response of Plant Height, Species Richness and Aboveground Biomass to Flooding Gradient along Vegetation Zones in Floodplain Wetlands, Northeast China.

Science.gov (United States)

Lou, Yanjing; Pan, Yanwen; Gao, Chuanyu; Jiang, Ming; Lu, Xianguo; Xu, Y Jun

2016-01-01

Flooding regime changes resulting from natural and human activity have been projected to affect wetland plant community structures and functions. It is therefore important to conduct investigations across a range of flooding gradients to assess the impact of flooding depth on wetland vegetation. We conducted this study to identify the pattern of plant height, species richness and aboveground biomass variation along the flooding gradient in floodplain wetlands located in Northeast China. We found that the response of dominant species height to the flooding gradient depends on specific species, i.e., a quadratic response for Carex lasiocarpa, a negative correlation for Calamagrostis angustifolia, and no response for Carex appendiculata. Species richness showed an intermediate effect along the vegetation zone from marsh to wet meadow while aboveground biomass increased. When the communities were analysed separately, only the water table depth had significant impact on species richness for two Carex communities and no variable for C. angustifolia community, while height of dominant species influenced aboveground biomass. When the three above-mentioned communities were grouped together, variations in species richness were mainly determined by community type, water table depth and community mean height, while variations in aboveground biomass were driven by community type and the height of dominant species. These findings indicate that if habitat drying of these herbaceous wetlands in this region continues, then two Carex marshes would be replaced gradually by C. angustifolia wet meadow in the near future. This will lead to a reduction in biodiversity and an increase in productivity and carbon budget. Meanwhile, functional traits must be considered, and should be a focus of attention in future studies on the species diversity and ecosystem function in this region.

Global assessment of experimental climate warming on tundra vegetation: heterogeneity over space and time.

Science.gov (United States)

Elmendorf, Sarah C; Henry, Gregory H R; Hollister, Robert D; Björk, Robert G; Bjorkman, Anne D; Callaghan, Terry V; Collier, Laura Siegwart; Cooper, Elisabeth J; Cornelissen, Johannes H C; Day, Thomas A; Fosaa, Anna Maria; Gould, William A; Grétarsdóttir, Járngerður; Harte, John; Hermanutz, Luise; Hik, David S; Hofgaard, Annika; Jarrad, Frith; Jónsdóttir, Ingibjörg Svala; Keuper, Frida; Klanderud, Kari; Klein, Julia A; Koh, Saewan; Kudo, Gaku; Lang, Simone I; Loewen, Val; May, Jeremy L; Mercado, Joel; Michelsen, Anders; Molau, Ulf; Myers-Smith, Isla H; Oberbauer, Steven F; Pieper, Sara; Post, Eric; Rixen, Christian; Robinson, Clare H; Schmidt, Niels Martin; Shaver, Gaius R; Stenström, Anna; Tolvanen, Anne; Totland, Orjan; Troxler, Tiffany; Wahren, Carl-Henrik; Webber, Patrick J; Welker, Jeffery M; Wookey, Philip A

2012-02-01

Understanding the sensitivity of tundra vegetation to climate warming is critical to forecasting future biodiversity and vegetation feedbacks to climate. In situ warming experiments accelerate climate change on a small scale to forecast responses of local plant communities. Limitations of this approach include the apparent site-specificity of results and uncertainty about the power of short-term studies to anticipate longer term change. We address these issues with a synthesis of 61 experimental warming studies, of up to 20 years duration, in tundra sites worldwide. The response of plant groups to warming often differed with ambient summer temperature, soil moisture and experimental duration. Shrubs increased with warming only where ambient temperature was high, whereas graminoids increased primarily in the coldest study sites. Linear increases in effect size over time were frequently observed. There was little indication of saturating or accelerating effects, as would be predicted if negative or positive vegetation feedbacks were common. These results indicate that tundra vegetation exhibits strong regional variation in response to warming, and that in vulnerable regions, cumulative effects of long-term warming on tundra vegetation - and associated ecosystem consequences - have the potential to be much greater than we have observed to date. © 2011 Blackwell Publishing Ltd/CNRS.

Nonlocal Response of Metallic Nanospheres Probed by Light, Electrons, and Atoms

DEFF Research Database (Denmark)

Christensen, Thomas; Yan, Wei; Raza, Søren

2014-01-01

Inspired by recent measurements on individual metallic nanospheres that cannot be explained with traditional classical electrodynamics, we theoretically investigate the effects of nonlocal response by metallic nanospheres in three distinct settings: atomic spontaneous emission, electron energy loss...... blueshifted surface plasmon but also an infinite series of bulk plasmons that have no counterpart in a local-response approximation. We show that these increasingly blueshifted multipole plasmons become spectrally more prominent at shorter probe-to-surface separations and for decreasing nanosphere radii...

Emergency Response Proficiency Test for Japanese Laboratories: Determination of Selected Radionuclides in Water, Soil, Vegetation and Aerosol Filters

International Nuclear Information System (INIS)

2013-01-01

Reliable determination of natural and artificial radionuclides in environmental samples is necessary for compliance with radiation protection and environmental regulations. The IAEA assists Member State laboratories in maintaining and improving their readiness in this regard by producing reference materials, by developing standardized analytical methods, and by conducting interlaboratory comparisons and proficiency tests as tools for quality control. To fulfil this obligation and ensure a reliable, rapid and consistent worldwide response, the IAEA Terrestrial Environment Laboratory in Seibersdorf, Austria, organizes interlaboratory comparisons and proficiency tests. In addition, the IAEA coordinates the worldwide network of Analytical Laboratories for the Measurement of Environmental Radioactivity (ALMERA). After the accident at the Fukushima Daiichi nuclear power plant in March 2011, Japan requested the IAEA to organize an emergency response proficiency test for Japanese laboratories with the aim of assessing their capacity to rapidly and accurately measure radionuclides in environmental samples. The IAEA responded to the request by assembling a special sample set covering the main environmental samples and radionuclides of interest in the case of a nuclear emergency situation. Water, soil, vegetation and aerosol filter samples were made available to Japanese laboratories for analysis by gamma ray spectrometry. This report presents the results of the IAEA-TEL-2011-08 emergency response proficiency test for Japanese laboratories on the determination of selected radionuclides in water, soil, vegetation and aerosol filters. The report includes descriptions of the methodologies and data evaluation approach used, as well as summary evaluations of each radionuclide and individual evaluation reports of each laboratory. This proficiency test was designed to identify analytical problems and to support Member State laboratories in their efforts to improve the quality of

Radionuclide accumulation peculiarities demonstrated by vegetable varieties

International Nuclear Information System (INIS)

Kruk, A.V.; Goncharenko, G.G.; Kilchevsky, A.V.

2004-01-01

This study focused on ecological and genetic aspects of radionuclide accumulation demonstrated by a number of vegetable varieties. The researches resulted in determining the cabbage varieties which were characterised by the minimal level of radionuclide accumulation. It was shown that the above varieties manifested the relation between radionuclide accumulation and morphobiological characteristics such as vegetation period duration and yield criteria. The study specified the genotypes with high ecological stability as regards to radionuclide accumulation: 'Beloruskaya 85' cabbage and 'Dokhodny' tomato showed the best response to Cs 137, while 'Beloruskaya 85', 'Rusinovka', 'Amager 611' cabbage varieties and 'Sprint' tomato showed the minimal level of Sr 90 accumulation. (authors)

Interactions of Vegetation and Climate: Remote Observations, Earth System Models, and the Amazon Forest

Science.gov (United States)

Quetin, Gregory R.

The natural composition of terrestrial ecosystems can be shaped by climate to take advantage of local environmental conditions. Ecosystem functioning, e.g. interaction between photosynthesis and temperature, can also acclimate to different climatological states. The combination of these two factors thus determines ecological-climate interactions. The ecosystem functioning also plays a key role in predicting the carbon cycle, hydrological cycle, terrestrial surface energy balance, and the feedbacks in the climate system. Predicting the response of the Earth's biosphere to global warming requires the ability to mechanistically represent the processes controlling ecosystem functioning through photosynthesis, respiration, and water use. The physical environment in a place shapes the vegetation there, but vegetation also has the potential to shape the environment, e.g. increased photosynthesis and transpiration moisten the atmosphere. These two-way ecoclimate interactions create the potential for feedbacks between vegetation at the physical environment that depend on the vegetation and the climate of a place, and can change throughout the year. In Chapter 1, we derive a global empirical map of the sensitivity of vegetation to climate using the response of satellite-observed greenness to interannual variations in temperature and precipitation. We infer mechanisms constraining ecosystem functioning by analyzing how the sensitivity of vegetation to climate varies across climate space. Our analysis yields empirical evidence for multiple physical and biological mediators of the sensitivity of vegetation to climate at large spatial scales. In hot and wet locations, vegetation is greener in warmer years despite temperatures likely exceeding thermally optimum conditions. However, sunlight generally increases during warmer years, suggesting that the increased stress from higher atmospheric water demand is offset by higher rates of photosynthesis. The sensitivity of vegetation

Drought is Coming: Monitoring Vegetation Response to Water Scarcity through Variable Chlorophyll a Fluorescence

Science.gov (United States)

Guadagno, C. R.; Beverly, D.; Pleban, J. R.; Speckman, H. N.; Ewers, B. E.; Weinig, C.

2017-12-01

Aridity is one of the most pronounced environmental limits to plant survival, and understanding how plants respond to drought and recovery is crucial for predicting impacts on managed and natural ecosystems. Changes in soil moisture conditions induce a suite of physiological responses from the cell to ecosystem scale, complicating the assessment of drought effects. Characterizing early indicators of water scarcity across species can inform biophysical models with improved understanding of plant hydraulics. While indexes exist for drought monitoring across scales, many are unable to identify imminent vegetative drought. We explore a method of early diagnosis using leaf-level and kinetic imaging measures of variable chlorophyll a fluorescence. This is a fast and reliable tool capturing leaf physiological changes in advance of changes in NDVI or passive solar induced fluorescence. Both image and leaf level Pulse Amplitude Method (PAM) measurements illustrate the utility of variable chlorophyll a fluorescence for monitoring vegetative drought. Variable fluorescence was monitored across populations of crops, desert shrubs, montane conifers and riparian deciduous trees under variable water regimes. We found a strong correlation (R = 0.85) between the maximum efficiency of photosystem II measured using variable fluorescence (Fv'Fm') and leaf level electrolyte leakage, a proximal cause of drought stress induced by cellular damage in leaves. This association was confirmed in two gymnosperm species (Picea engelmannii and Pinus contorta) and for diverse varieties of the crop species Brassica rapa. The use of chlorophyll a fluorescence per image also allowed for early detection of drought in aspen (Populus tremuloides). These results provide evidence that variable chlorophyll fluorescence decreases between 25% and 70% in mild and severely droughted twigs with respect to ones collected from trees in wet soil conditions. While current systems for monitoring variable fluorescence

Quantitative indicators of fruit and vegetable consumption

Directory of Open Access Journals (Sweden)

Dagmar Kozelová

2015-12-01

Full Text Available The quantitative research of the market is often based on surveys and questionnaires which are finding out the behavior of customers in observed areas. Before purchasing process consumers consider where they will buy fruit and vegetables, what kind to choose and in what quantity of goods. Consumers' behavior is affected by the factors as: regional gastronomic traditions, price, product appearance, aroma, place of buying, own experience and knowledge, taste preferences as well as specific health issues of consumers and others. The consumption of fruit and vegetables brings into the human body biological active substances that favorably affect the health of consumers. In the presented research study we were interested in differences of consumers' behavior in the consumption of fruit and vegetables according to the place of residence and gender. In the survey 200 respondents has participated; their place of residence was city or village. The existence of dependences and statistical significance were examined by selected statistical testing methods. Firstly we analyzed the responses via statistical F-test whether observed random samples have the same variance. Then we applied two-sample unpaired t-test with equal variance and χ2-test of statistical independence. The statistical significance was tested by corresponding p values. Correlations were proved by the Cramer's V coefficient. We found that place of residence has no impact on the respondents' consumption of fruit. The gender of respondents does not affect their consumption of fruit. Equally, the gender does not affect the respondents' consumption of vegetables. Only in one observed case the significant differences proved that the place of respondent residence has impact on the consumption of vegetables. Higher consumption of vegetables is due to the fact that the majority of citizens, who live in villages, have a possibility to grow their own vegetables and, thus, the demand for it in village

Plasma response to electron energy filter in large volume plasma device

International Nuclear Information System (INIS)

Sanyasi, A. K.; Awasthi, L. M.; Mattoo, S. K.; Srivastava, P. K.; Singh, S. K.; Singh, R.; Kaw, P. K.

2013-01-01

An electron energy filter (EEF) is embedded in the Large Volume Plasma Device plasma for carrying out studies on excitation of plasma turbulence by a gradient in electron temperature (ETG) described in the paper of Mattoo et al. [S. K. Mattoo et al., Phys. Rev. Lett. 108, 255007 (2012)]. In this paper, we report results on the response of the plasma to the EEF. It is shown that inhomogeneity in the magnetic field of the EEF switches on several physical phenomena resulting in plasma regions with different characteristics, including a plasma region free from energetic electrons, suitable for the study of ETG turbulence. Specifically, we report that localized structures of plasma density, potential, electron temperature, and plasma turbulence are excited in the EEF plasma. It is shown that structures of electron temperature and potential are created due to energy dependence of the electron transport in the filter region. On the other hand, although structure of plasma density has origin in the particle transport but two distinct steps of the density structure emerge from dominance of collisionality in the source-EEF region and of the Bohm diffusion in the EEF-target region. It is argued and experimental evidence is provided for existence of drift like flute Rayleigh-Taylor in the EEF plasma

Fatal attraction: vegetation responses to nutrient inputs attract herbivores to infectious anthrax carcass sites.

Science.gov (United States)

Turner, Wendy C; Kausrud, Kyrre L; Krishnappa, Yathin S; Cromsigt, Joris P G M; Ganz, Holly H; Mapaure, Isaac; Cloete, Claudine C; Havarua, Zepee; Küsters, Martina; Getz, Wayne M; Stenseth, Nils Chr

2014-11-22

Parasites can shape the foraging behaviour of their hosts through cues indicating risk of infection. When cues for risk co-occur with desired traits such as forage quality, individuals face a trade-off between nutrient acquisition and parasite exposure. We evaluated how this trade-off may influence disease transmission in a 3-year experimental study of anthrax in a guild of mammalian herbivores in Etosha National Park, Namibia. At plains zebra (Equus quagga) carcass sites we assessed (i) carcass nutrient effects on soils and grasses, (ii) concentrations of Bacillus anthracis (BA) on grasses and in soils, and (iii) herbivore grazing behaviour, compared with control sites, using motion-sensing camera traps. We found that carcass-mediated nutrient pulses improved soil and vegetation, and that BA is found on grasses up to 2 years after death. Host foraging responses to carcass sites shifted from avoidance to attraction, and ultimately to no preference, with the strength and duration of these behavioural responses varying among herbivore species. Our results demonstrate that animal carcasses alter the environment and attract grazing hosts to parasite aggregations. This attraction may enhance transmission rates, suggesting that hosts are limited in their ability to trade off nutrient intake with parasite avoidance when relying on indirect cues. © 2014 The Author(s) Published by the Royal Society. All rights reserved.

Climatic factors driving vegetation declines in the 2005 and 2010 Amazon droughts.

Directory of Open Access Journals (Sweden)

Wenqian Zhao

Full Text Available Along with global climate change, the occurrence of extreme droughts in recent years has had a serious impact on the Amazon region. Current studies on the driving factors of the 2005 and 2010 Amazon droughts has focused on the influence of precipitation, whereas the impacts of temperature and radiation have received less attention. This study aims to explore the climate-driven factors of Amazonian vegetation decline during the extreme droughts using vegetation index, precipitation, temperature and radiation datasets. First, time-lag effects of Amazonian vegetation responses to precipitation, radiation and temperature were analyzed. Then, a multiple linear regression model was established to estimate the contributions of climatic factors to vegetation greenness, from which the dominant climate-driving factors were determined. Finally, the climate-driven factors of Amazonian vegetation greenness decline during the 2005 and 2010 extreme droughts were explored. The results showed that (i in the Amazon vegetation greenness responded to precipitation, radiation and temperature, with apparent time lags for most averaging interval periods associated with vegetation index responses of 0-4, 0-9 and 0-6 months, respectively; (ii on average, the three climatic factors without time lags explained 27.28±21.73% (mean±1 SD of vegetation index variation in the Amazon basin, and this value increased by 12.22% and reached 39.50±27.85% when time lags were considered; (iii vegetation greenness in this region in non-drought years was primarily affected by precipitation and shortwave radiation, and these two factors altogether accounted for 93.47% of the total explanation; and (iv in the common epicenter of the two droughts, pixels with a significant variation in precipitation, radiation and temperature accounted for 36.68%, 40.07% and 10.40%, respectively, of all pixels showing a significant decrease in vegetation index in 2005, and 15.69%, 2.01% and 45.25% in

Total-dielectric-function approach to electron and phonon response in solids

International Nuclear Information System (INIS)

Penn, D.R.; Lewis, S.P.; Cohen, M.L.

1995-01-01

The interaction between two test charges, the response of a solid to an external field, and the normal modes of the solid can be determined from a total dielectric function that includes both electronic and lattice polarizabilities as well as local-field effects. In this paper we examine the relationship between superconductivity and the stability of a solid and derive sum rules for the electronic part of the dielectric function. It is also shown that there are negative eigenvalues of the total static dielectric function, implying the possibility of an attractive interaction between test charges. An attractive interaction is required for superconductivity

Global changes in dryland vegetation dynamics (1988–2008 assessed by satellite remote sensing: comparing a new passive microwave vegetation density record with reflective greenness data

Directory of Open Access Journals (Sweden)

N. Andela

2013-10-01

Full Text Available Drylands, covering nearly 30% of the global land surface, are characterized by high climate variability and sensitivity to land management. Here, two satellite-observed vegetation products were used to study the long-term (1988–2008 vegetation changes of global drylands: the widely used reflective-based Normalized Difference Vegetation Index (NDVI and the recently developed passive-microwave-based Vegetation Optical Depth (VOD. The NDVI is sensitive to the chlorophyll concentrations in the canopy and the canopy cover fraction, while the VOD is sensitive to vegetation water content of both leafy and woody components. Therefore it can be expected that using both products helps to better characterize vegetation dynamics, particularly over regions with mixed herbaceous and woody vegetation. Linear regression analysis was performed between antecedent precipitation and observed NDVI and VOD independently to distinguish the contribution of climatic and non-climatic drivers in vegetation variations. Where possible, the contributions of fire, grazing, agriculture and CO2 level to vegetation trends were assessed. The results suggest that NDVI is more sensitive to fluctuations in herbaceous vegetation, which primarily uses shallow soil water, whereas VOD is more sensitive to woody vegetation, which additionally can exploit deeper water stores. Globally, evidence is found for woody encroachment over drylands. In the arid drylands, woody encroachment appears to be at the expense of herbaceous vegetation and a global driver is interpreted. Trends in semi-arid drylands vary widely between regions, suggesting that local rather than global drivers caused most of the vegetation response. In savannas, besides precipitation, fire regime plays an important role in shaping trends. Our results demonstrate that NDVI and VOD provide complementary information and allow new insights into dryland vegetation dynamics.

Simulations of Vegetation Impacts on Arctic Climate

Science.gov (United States)

Bonfils, C.; Phillips, T. J.; Riley, W. J.; Post, W. M.; Torn, M. S.

2009-12-01

Because global warming disproportionately influences high-latitude climate, changes in arctic vegetation are in progress. These land-cover changes include redistribution of local vegetation types as well as northward migration of lower-latitude species in response to the increasing warming. The resulting displacement of low-lying tundra vegetation by shrubs and trees darkens the surface, thus accelerating regional warming. As participants in the U.S. Department of Energy IMPACTS Project, we are investigating the potential for abrupt arctic climatic change resulting from such variations in vegetation, among other mechanisms. To estimate the relative magnitudes of effects to be expected from changes in high-latitude land cover, we are conducting several numerical experiments with the Community Climate System Model (CCSM). These experiments include: 1) A “present-day-climate” control experiment with current atmospheric greenhouse-gas concentrations and climatological monthly sea surface temperatures and sea ice extents prescribed, and with “standard” CLM plant functional types (PFTs) specified; 2) A “changed-vegetation-type” experiment that is the same as 1), except that the “standard” PFTs are augmented by additional vegetation types (forbs, sedges, shrubs, mosses, and lichens) that are not presently represented in CLM. This experiment will require information on the location, fractional cover, and physiological parameterizations of these new PFTs. 3) A “changed-vegetation-extent experiment” that is the same as 2), except that the spatial extents of selected PFTs (e.g. shrubs or boreal forest PFTs) are shifted northward from their present locations in the CLM. We will report on the atmospheric climate and land-surface feedbacks associated with these vegetation changes, with emphasis on local and regional surface energy and moisture fluxes and near-surface temperature, humidity, and clouds. Acknowledgments This work was performed under the auspices

Statistical Models for Inferring Vegetation Composition from Fossil Pollen

Science.gov (United States)

Paciorek, C.; McLachlan, J. S.; Shang, Z.

2011-12-01

Fossil pollen provide information about vegetation composition that can be used to help understand how vegetation has changed over the past. However, these data have not traditionally been analyzed in a way that allows for statistical inference about spatio-temporal patterns and trends. We build a Bayesian hierarchical model called STEPPS (Spatio-Temporal Empirical Prediction from Pollen in Sediments) that predicts forest composition in southern New England, USA, over the last two millenia based on fossil pollen. The critical relationships between abundances of tree taxa in the pollen record and abundances in actual vegetation are estimated using modern (Forest Inventory Analysis) data and (witness tree) data from colonial records. This gives us two time points at which both pollen and direct vegetation data are available. Based on these relationships, and incorporating our uncertainty about them, we predict forest composition using fossil pollen. We estimate the spatial distribution and relative abundances of tree species and draw inference about how these patterns have changed over time. Finally, we describe ongoing work to extend the modeling to the upper Midwest of the U.S., including an approach to infer tree density and thereby estimate the prairie-forest boundary in Minnesota and Wisconsin. This work is part of the PalEON project, which brings together a team of ecosystem modelers, paleoecologists, and statisticians with the goal of reconstructing vegetation responses to climate during the last two millenia in the northeastern and midwestern United States. The estimates from the statistical modeling will be used to assess and calibrate ecosystem models that are used to project ecological changes in response to global change.

Incineration of Low Level Radioactive Vegetation for Waste Volume Reduction

International Nuclear Information System (INIS)

Malik, N.P.S.; Rucker, G.G.; Looper, M.G.

1995-01-01

The DOE changing mission at Savannah River Site (SRS) are to increase activities for Waste Management and Environmental Restoration. There are a number of Comprehensive Environmental Response, Compensation and Liability Act (CERCLA) locations that are contaminated with radioactivity and support dense vegetation, and are targeted for remediation. Two such locations have been studied for non-time critical removal actions under the National Contingency Plan (NCP). Both of these sites support about 23 plant species. Surveys of the vegetation show that radiation emanates mainly from vines, shrubs, and trees and range from 20,000 to 200,000 d/m beta gamma. Planning for removal and disposal of low-level radioactive vegetation was done with two principal goals: to process contaminated vegetation for optimum volume reduction and waste minimization, and for the protection of human health and environment. Four alternatives were identified as candidates for vegetation removal and disposal: chipping the vegetation and packing in carbon steel boxes (lined with synthetic commercial liners) and disposal at the Solid Waste Disposal Facility at SRS; composting the vegetation; burning the vegetation in the field; and incinerating the vegetation. One alternative 'incineration' was considered viable choice for waste minimization, safe handling, and the protection of the environment and human health. Advantages and disadvantages of all four alternatives considered have been evaluated. For waste minimization and ultimate disposal of radioactive vegetation incineration is the preferred option. Advantages of incineration are that volume reduction is achieved and low-level radioactive waste are stabilized. For incineration and final disposal vegetation will be chipped and packed in card board boxes and discharged to the rotary kiln of the incinerator. The slow rotation and longer resident time in the kiln will ensure complete combustion of the vegetative material

Magnetospheric Response Associated With Multiple Atmospheric Reflections of Precipitated Electrons in Aurora.

Science.gov (United States)

Khazanov, G. V.; Merkin, V. G.; Zesta, E.; Sibeck, D. G.; Grubbs, G. A., II; Chu, M.; Wiltberger, M. J.

2017-12-01

The magnetosphere and ionosphere are strongly coupled by precipitating electrons during storm times. Therefore, first principle simulations of precipitating electron fluxes are required to understand storm time variations of ionospheric conductances and related electric fields. As has been discussed by Khazanov et al. [2015 - 2017], the first step in such simulations is initiation of electron precipitation from the Earth's plasma sheet via wave particle interaction processes into both magnetically conjugate points, and the step 2 is the follow up of multiple atmospheric reflections of electron fluxes formed at the boundary between the ionosphere and magnetosphere of two magnetically conjugate points. To demonstrate this effect on the global magnetospheric response the Lyon-Fedder-Mobarry global magnetosphere model coupled with the Rice Convection Model of the inner magnetosphere has been used and run for the geomagnetic storm of 17 March 2013.

Pattern Decomposition Method and a New Vegetation Index for Hyper-Multispectral Satellite Data Analysis

Science.gov (United States)

Muramatsu, K.; Furumi, S.; Hayashi, A.; Shiono, Y.; Ono, A.; Fujiwara, N.; Daigo, M.; Ochiai, F.

We have developed the ``pattern decomposition method'' based on linear spectral mixing of ground objects for n-dimensional satellite data. In this method, spectral response patterns for each pixel in an image are decomposed into three components using three standard spectral shape patterns determined from the image data. Applying this method to AMSS (Airborne Multi-Spectral Scanner) data, eighteen-dimensional data are successfully transformed into three-dimensional data. Using the three components, we have developed a new vegetation index in which all the multispectral data are reflected. We consider that the index should be linear to the amount of vegetation and vegetation vigor. To validate the index, its relations to vegetation types, vegetation cover ratio, and chlorophyll contents of a leaf were studied using spectral reflectance data measured in the field with a spectrometer. The index was sensitive to vegetation types and vegetation vigor. This method and index are very useful for assessment of vegetation vigor, classifying land cover types and monitoring vegetation changes

Post-fire vegetation recovery in Portugal based on spot/vegetation data

Science.gov (United States)

Gouveia, C.; Dacamara, C. C.; Trigo, R. M.

2010-04-01

A procedure is presented that allows identifying large burned scars and the monitoring of vegetation recovery in the years following major fire episodes. The procedure relies on 10-day fields of Maximum Value Composites of Normalized Difference Vegetation Index (MVC-NDVI), with a 1 km×1 km spatial resolution obtained from the VEGETATION instrument. The identification of fire scars during the extremely severe 2003 fire season is performed based on cluster analysis of NDVI anomalies that persist during the vegetative cycle of the year following the fire event. Two regions containing very large burned scars were selected, located in Central and Southwestern Portugal, respectively, and time series of MVC-NDVI analysed before the fire events took place and throughout the post-fire period. It is shown that post-fire vegetation dynamics in the two selected regions may be characterised based on maps of recovery rates as estimated by fitting a monoparametric model of vegetation recovery to MVC-NDVI data over each burned scar. Results indicated that the recovery process in the region located in Central Portugal is mostly related to fire damage rather than to vegetation density before 2003, whereas the latter seems to have a more prominent role than vegetation conditions after the fire episode, e.g. in the case of the region in Southwestern Portugal. These differences are consistent with the respective predominant types of vegetation. The burned area located in Central Portugal is dominated by Pinus Pinaster whose natural regeneration crucially depends on the destruction of seeds present on the soil surface during the fire, whereas the burned scar in Southwestern Portugal was populated by Eucalyptus that may quickly re-sprout from buds after fire. Besides its simplicity, the monoparametric model of vegetation recovery has the advantage of being easily adapted to other low-resolution satellite data, as well as to other types of vegetation indices.

Sink limitation induces the expression of multiple soybean vegetative lipoxygenase mRNAs while the endogenous jasmonic acid level remains low.

Science.gov (United States)

Bunker, T W; Koetje, D S; Stephenson, L C; Creelman, R A; Mullet, J E; Grimes, H D

1995-08-01

The response of individual members of the lipoxygenase multigene family in soybeans to sink deprivation was analyzed. RNase protection assays indicated that a novel vegetative lipoxygenase gene, vlxC, and three other vegetative lipoxygenase mRNAs accumulated in mature leaves in response to a variety of sink limitations. These data suggest that several members of the lipoxygenase multigene family are involved in assimilate partitioning. The possible involvement of jasmonic acid as a signaling molecule regulating assimilate partitioning into the vegetative storage proteins and lipoxygenases was directly assessed by determining the endogenous level of jasmonic acid in leaves from plants with their pods removed. There was no rise in the level of endogenous jasmonic acid coincident with the strong increase in both vlxC and vegetative storage protein VspB transcripts in response to sink limitation. Thus, expression of the vegetative lipoxygenases and vegetative storage proteins is not regulated by jasmonic acid in sink-limited leaves.

The Impact of the Rise in Vegetable Prices on Vegetable Producer Behavior–Based on the survey of vegetable producers in Jiayu, Hubei Province

Directory of Open Access Journals (Sweden)

Liu Pan

2015-01-01

Full Text Available In order to study the impact of the rise in prices of vegetables on vegetable producers, and to increase the revenue of vegetable producers, this paper does a survey by anonymous sampling questionnaire. Results shows that: most vegetable growers think that vegetable prices should rise and would continue to rise, and that vegetable prices would increase their revenue, thus in the coming year they would expand the planting scale of vegetable variety whose increase rate is the largest in this year. But because of the increase of logistics costs and production costs, some farmers benefit very little from the rising trend of vegetable prices. Most farmers expect too much in the trend estimation of the prices of vegetables and also lack of planning and forward-looking in production, thus the planting area of single variety is often decided by the market of previous year. According to analysis of the impact of the rise in vegetable prices on vegetable producer behavior, this paper gives the following suggestions to increase revenue of vegetable producers: change the mode of thinking, improve rural information platform, and increase capital investment for vegetable production base.

Radiative transfer in shrub savanna sites in Niger: preliminary results from HAPEX-Sahel. 3. Optical dynamics and vegetation index sensitivity to biomass and plant cover

International Nuclear Information System (INIS)

Leeuwen, W.J.D. van; Huete, A.R.; Duncan, J.; Franklin, J.

1994-01-01

A shrub savannah landscape in Niger was optically characterized utilizing blue, green, red and near-infrared wavelengths. Selected vegetation indices were evaluated for their performance and sensitivity to describe the complex Sahelian soil/vegetation canopies. Bidirectional reflectance factors (BRF) of plants and soils were measured at several view angles, and used as input to various vegetation indices. Both soil and vegetation targets had strong anisotropic reflectance properties, rendering all vegetation index (VI) responses to be a direct function of sun and view geometry. Soil background influences were shown to alter the response of most vegetation indices. N-space greenness had the smallest dynamic range in VI response, but the n-space brightness index provided additional useful information. The global environmental monitoring index (GEMI) showed a large VI dynamic range for bare soils, which was undesirable for a vegetation index. The view angle response of the normalized difference vegetation index (NDVI), atmosphere resistant vegetation index (ARVI) and soil atmosphere resistant vegetation index (SARVI) were asymmetric about nadir for multiple view angles, and were, except for the SARVI, altered seriously by soil moisture and/or soil brightness effects. The soil adjusted vegetation index (SAVI) was least affected by surface soil moisture and was symmetric about nadir for grass vegetation covers. Overall the SAVI, SARVI and the n-space vegetation index performed best under all adverse conditions and were recommended to monitor vegetation growth in the sparsely vegetated Sahelian zone. (author)

Modelling post-fire vegetation recovery in Portugal

Directory of Open Access Journals (Sweden)

A. Bastos

2011-12-01

Full Text Available Wildfires in Mediterranean Europe have been increasing in number and extension over the last decades and constitute one of the major disturbances of these ecosystems. Portugal is the country with more burnt area in the last decade and the years of 2003 and 2005 were particularly devastating, the total burned areas of 425 000 and 338 000 ha being several times higher than the corresponding average. The year of 2005 further coincided with one of the most severe droughts since early 20th century. Due to different responses of vegetation to diverse fire regimes and to the complexity of landscape structures, fires have complex effects on vegetation recovery. Remote sensing has revealed to be a powerful tool in studying vegetation dynamics and in monitoring post-fire vegetation recovery, which is crucial to land-management and to prevent erosion.

The main goals of the present work are (i to assess the accuracy of a vegetation recovery model previously developed by the authors; (ii to assess the model's performance, namely its sensitivity to initial conditions, to the temporal length of the input dataset and to missing data; (iii to study vegetation recovery over two selected areas that were affected by two large wildfire events in the fire seasons of 2003 and 2005, respectively.

The study relies on monthly values of NDVI over 11 years (1998–2009, at 1 km × 1 km spatial resolution, as obtained by the VEGETATION instrument. According to results from sensitivity analysis, the model is robust and able to provide good estimations of recovery times of vegetation when the regeneration process is regular, even when missing data is present. In respect to the two selected burnt scars, results indicate that fire damage is a determinant factor of regeneration, as less damaged vegetation recovers more rapidly, which is mainly justified by the high coverage of Pinus pinaster over the area, and by the fact that coniferous forests tend to

Soil borne gungi associated with different vegetable crop in sindh, pakistan

International Nuclear Information System (INIS)

Usman, F.; Abid, M.; Hussain, F.

2014-01-01

Different soil-borne fungi are responsible for reducing the yield of vegetables throughout the world including Pakistan. There are several soil borne fungal pathogens which aggressively infect vegetable crops. Surveys conducted during September 2010 to October 2011, demonstrated that a great diversity of soil borne plant pathogens associated with different vegetables prevail in vegetable growing areas of Sindh such as Tando Allahayar, Mirpurkhas, Ghotaki, Khairpur, Kunri, Umerkot and Karachi, etc. Our study noted in total thirteen different genera of fungi isolated from vegetable crops (cabbage, brinjal, tomato, radish and spinach). Isolated fungi identified included Alternaria solani, Aspergillus flavus, A. fumigatus, A. niger, A. oryzae, A. terrus, Aeromonium fusidiocles, Cladosporium sp., Drechselra hawaiiensis, Eurotium berbanbrum, Fusarium oxysporum, Macrophomina phaseolina, Penicillium commune, Rhizoctonia solani, Trichoderma harzianum, Ulocladium sp., and unidentified black mycelium from the soil and roots of vegetable crops. In addition, it was found that soil is commonly infected by soil-borne fungi and eventually results in heavy losses of vegetable yield in the vegetable growing areas of Sindh province. The infection rapidly increased due to many factors such as, presence of moisture, excess of water and infection may be caused by winds, gales and dust storms as well as by mechanical vectors. (author)

Global assessment of experimental climate warming on tundra vegetation

DEFF Research Database (Denmark)

Elmendorf, Sarah C.; Henry, Gregory H.R.; Hollister, Robert D.

2012-01-01

Understanding the sensitivity of tundra vegetation to climate warming is critical to forecasting future biodiversity and vegetation feedbacks to climate. In situ warming experiments accelerate climate change on a small scale to forecast responses of local plant communities. Limitations...... of this approach include the apparent site-specificity of results and uncertainty about the power of short-term studies to anticipate longer term change. We address these issues with a synthesis of 61 experimental warming studies, of up to 20 years duration, in tundra sites worldwide. The response of plant groups...... to warming often differed with ambient summer temperature, soil moisture and experimental duration. Shrubs increased with warming only where ambient temperature was high, whereas graminoids increased primarily in the coldest study sites. Linear increases in effect size over time were frequently observed...

Impact of vegetation feedback at subseasonal & seasonal timescales on precipitation over North America

Science.gov (United States)

Kim, Y.; Wang, G.

2006-05-01

Soil moisture-vegetation-precipitation feedbacks tend to enhance soil moisture memory in some areas of the globe, which contributes to the subseasonal and seasonal climate prediction skill. In this study, the impact of vegetation on precipitation over North America is investigated using a coupled land-atmosphere model CAM3- CLM3. The coupled model has been modified to include a predictive vegetation phenology scheme and validated against the MODIS data. Vegetation phenology is modeled by updating the leaf area index (LAI) daily in response to cumulative and concurrent hydrometeorological conditions. First, driven with the climatological SST, a large group of 5-member ensembles of simulations from the late spring and summer to the end of year are generated with the different initial conditions of soil moisture. The impact of initial soil moisture anomalies on subsequent precipitation is examined with the predictive vegetation phenology scheme disabled/enabled ("SM"/"SM_Veg" ensembles). The simulated climate differences between "SM" and "SM_Veg" ensembles represent the role of vegetation in soil moisture-vegetation- precipitation feedback. Experiments in this study focus on how the response of precipitation to initial soil moisture anomalies depends on their characteristics, including the timing, magnitude, spatial coverage and vertical depth, and further how it is modified by the interactive vegetation. Our results, for example, suggest that the impact of late spring soil moisture anomalies is not evident in subsequent precipitation until early summer when local convective precipitation dominates. With the summer wet soil moisture anomalies, vegetation tends to enhance the positive feedback between soil moisture and precipitation, while vegetation tends to suppress such positive feedback with the late spring anomalies. Second, the impact of vegetation feedback is investigated by driving the model with the inter-annually varying monthly SST (1983-1994). With the

Lumped Parameter Modeling for Rapid Vibration Response Prototyping and Test Correlation for Electronic Units

Science.gov (United States)

Van Dyke, Michael B.

2013-01-01

Present preliminary work using lumped parameter models to approximate dynamic response of electronic units to random vibration; Derive a general N-DOF model for application to electronic units; Illustrate parametric influence of model parameters; Implication of coupled dynamics for unit/board design; Demonstrate use of model to infer printed wiring board (PWB) dynamics from external chassis test measurement.

Response of Plant Height, Species Richness and Aboveground Biomass to Flooding Gradient along Vegetation Zones in Floodplain Wetlands, Northeast China

Science.gov (United States)

Lou, Yanjing; Pan, Yanwen; Gao, Chuanyu; Jiang, Ming; Lu, Xianguo; Xu, Y. Jun

2016-01-01

Flooding regime changes resulting from natural and human activity have been projected to affect wetland plant community structures and functions. It is therefore important to conduct investigations across a range of flooding gradients to assess the impact of flooding depth on wetland vegetation. We conducted this study to identify the pattern of plant height, species richness and aboveground biomass variation along the flooding gradient in floodplain wetlands located in Northeast China. We found that the response of dominant species height to the flooding gradient depends on specific species, i.e., a quadratic response for Carex lasiocarpa, a negative correlation for Calamagrostis angustifolia, and no response for Carex appendiculata. Species richness showed an intermediate effect along the vegetation zone from marsh to wet meadow while aboveground biomass increased. When the communities were analysed separately, only the water table depth had significant impact on species richness for two Carex communities and no variable for C. angustifolia community, while height of dominant species influenced aboveground biomass. When the three above-mentioned communities were grouped together, variations in species richness were mainly determined by community type, water table depth and community mean height, while variations in aboveground biomass were driven by community type and the height of dominant species. These findings indicate that if habitat drying of these herbaceous wetlands in this region continues, then two Carex marshes would be replaced gradually by C. angustifolia wet meadow in the near future. This will lead to a reduction in biodiversity and an increase in productivity and carbon budget. Meanwhile, functional traits must be considered, and should be a focus of attention in future studies on the species diversity and ecosystem function in this region. PMID:27097325

Hydrological and vegetational response to the Younger Dryas climatic oscillations: a high resolution case study from Quoyloo Meadow, Orkney, Scotland

Science.gov (United States)

Maas, David; Abrook, Ashley; Timms, Rhys; Matthews, Ian; Palmer, Adrian; Milner, Alice; Candy, Ian; Sachse, Dirk

2016-04-01

The Younger Dryas (Loch Lomond) Stadial is a well defined period of cold climate that in North West Europe punctuated the climatic amelioration during the Last Glacial - Interglacial Transition (LGIT ca. 16-8 ka). A palaeolake record from Quoyloo Meadow, Orkney Islands (N59.067, E-3.309) has been analysed for pollen and stable isotopes on biomarker lipids. n-Alkanes from terrestrial and aquatic sources are present throughout the core. The average chain length (ACL) is relatively low during the interstadial (~28.0) and shows a distinct increase during the Younger Dryas (to 29.0 +), attributed to an increase in grasses and drought resistant shrubs (e.g. Artemisia, Castañeda et al., 2009, Bunting, 1994). At the beginning of the Holocene, the ACL rapidly drops to 28.3 and from thereon gently increases again to ~29.0. There is a continued odd-over-even n-alkane predominance, although even n-alkanes are present in greater quantities in the interstadial, indicating an increasing terrestrial contribution in the Holocene. Ongoing deuterium isotope measurements of the n-alkanes will give independent evidence for palaeohydrological changes and can be compared to the other proxy evidence within the same core. Using a combination of nC29 and nC23 (terrestrial and aquatic end-members, respectively), a change in relative humidity (rH) can be qualified. This is based on the idea that terrestrial vegetation is affected by evapotranspiration processes, whereas aquatic vegetation is not (Rach et al., 2014). This data is supported by a high resolution palynological study; the contiguously sampled record demonstrates ecosystem/environmental responses to millennial-scale climatic change and allows for the possible detection of vegetation shifts at the sub-millennial scale. Vegetation aside, the pollen data can further aid in the interpretation of the recorded n-alkanes and isotopic analyses. This data is placed within a chronological framework derived from a high resolution crypto- and

Influence of seasoning on vegetable selection, liking and intent to purchase.

Science.gov (United States)

Manero, Joanna; Phillips, Carter; Ellison, Brenna; Lee, Soo-Yeun; Nickols-Richardson, Sharon M; Chapman-Novakofski, Karen M

2017-09-01

Low vegetable intake continues to be a health concern, and strategies to increase vegetable intake have resulted in only small increases. One strategy that has received less attention is the use of seasonings. This study's objective was to determine the impact of seasoning on vegetable selection, liking, and intent to purchase. We conducted a 3-week study in a public café on a university campus. Customers buying a main dish could select a vegetable side (seasoned [SS] or steamed [ST]) at no cost. Based on café data and power analysis (alpha 0.05, 80% power), 2 days per vegetable pair were conducted with carrot, broccoli, and green bean pairs randomized 3 days/week 1 and 3, with normal service week 2. Selection was greater for SS vs ST, n = 335 vs. 143 for all 3 vegetables combined; n = 97 vs 47 for carrots; n = 114 vs. 55 for broccoli; n = 124 vs. 41 for green beans (p purchase the vegetable that they selected. More customers chose the 'somewhat likely' and 'very likely' (n = 353) than the 'not likely' and 'definitely would not' (n = 121) purchase responses. Regression showed that people who did not often consume a vegetable with lunch while dining out were 1.59 times more likely to select the SS vegetables over the ST (p = 0.007). Given a choice, consumers were more likely to select a seasoned vegetable. With low vegetable consumption as a predictor of seasoned vegetable choice, offering seasoned vegetables may increase intake in those with poor vegetable intake in a café setting. Copyright © 2017 The Authors. Published by Elsevier Ltd.. All rights reserved.

Estimation of vegetation cover resilience from satellite time series

Directory of Open Access Journals (Sweden)

T. Simoniello

2008-07-01

Full Text Available Resilience is a fundamental concept for understanding vegetation as a dynamic component of the climate system. It expresses the ability of ecosystems to tolerate disturbances and to recover their initial state. Recovery times are basic parameters of the vegetation's response to forcing and, therefore, are essential for describing realistic vegetation within dynamical models. Healthy vegetation tends to rapidly recover from shock and to persist in growth and expansion. On the contrary, climatic and anthropic stress can reduce resilience thus favouring persistent decrease in vegetation activity.

In order to characterize resilience, we analyzed the time series 1982–2003 of 8 km GIMMS AVHRR-NDVI maps of the Italian territory. Persistence probability of negative and positive trends was estimated according to the vegetation cover class, altitude, and climate. Generally, mean recovery times from negative trends were shorter than those estimated for positive trends, as expected for vegetation of healthy status. Some signatures of inefficient resilience were found in high-level mountainous areas and in the Mediterranean sub-tropical ones. This analysis was refined by aggregating pixels according to phenology. This multitemporal clustering synthesized information on vegetation cover, climate, and orography rather well. The consequent persistence estimations confirmed and detailed hints obtained from the previous analyses. Under the same climatic regime, different vegetation resilience levels were found. In particular, within the Mediterranean sub-tropical climate, clustering was able to identify features with different persistence levels in areas that are liable to different levels of anthropic pressure. Moreover, it was capable of enhancing reduced vegetation resilience also in the southern areas under Warm Temperate sub-continental climate. The general consistency of the obtained results showed that, with the help of suited analysis

Environmental variation, vegetation distribution, carbon dynamics and water/energy exchange at high latitudes

Science.gov (United States)

McGuire, A.D.; Wirth, C.; Apps, M.; Beringer, J.; Clein, J.; Epstein, H.; Kicklighter, D.W.; Bhatti, J.; Chapin, F. S.; De Groot, B.; Efremov, D.; Eugster, W.; Fukuda, M.; Gower, T.; Hinzman, L.; Huntley, B.; Jia, G.J.; Kasischke, E.; Melillo, J.; Romanovsky, V.; Shvidenko, A.; Vaganov, E.; Walker, D.

2002-01-01

The responses of high latitude ecosystems to global change involve complex interactions among environmental variables, vegetation distribution, carbon dynamics, and water and energy exchange. These responses may have important consequences for the earth system. In this study, we evaluated how vegetation distribution, carbon stocks and turnover, and water and energy exchange are related to environmental variation spanned by the network of the IGBP high latitude transects. While the most notable feature of the high latitude transects is that they generally span temperature gradients from southern to northern latitudes, there are substantial differences in temperature among the transects. Also, along each transect temperature co-varies with precipitation and photosynthetically active radiation, which are also variable among the transects. Both climate and disturbance interact to influence latitudinal patterns of vegetation and soil carbon storage among the transects, and vegetation distribution appears to interact with climate to determine exchanges of heat and moisture in high latitudes. Despite limitations imposed by the data we assembled, the analyses in this study have taken an important step toward clarifying the complexity of interactions among environmental variables, vegetation distribution, carbon stocks and turnover, and water and energy exchange in high latitude regions. This study reveals the need to conduct coordinated global change studies in high latitudes to further elucidate how interactions among climate, disturbance, and vegetation distribution influence carbon dynamics and water and energy exchange in high latitudes.

Vegetation mapping of the Mond Protected Area of Bushehr Province (south-west Iran).

Science.gov (United States)

Mehrabian, Ahmadreza; Naqinezhad, Alireza; Mahiny, Abdolrassoul Salman; Mostafavi, Hossein; Liaghati, Homan; Kouchekzadeh, Mohsen

2009-03-01

Arid regions of the world occupy up to 35% of the earth's surface, the basis of various definitions of climatic conditions, vegetation types or potential for food production. Due to their high ecological value, monitoring of arid regions is necessary and modern vegetation studies can help in the conservation and management of these areas. The use of remote sensing for mapping of desert vegetation is difficult due to mixing of the spectral reflectance of bright desert soils with the weak spectral response of sparse vegetation. We studied the vegetation types in the semiarid to arid region of Mond Protected Area, south-west Iran, based on unsupervised classification of the Spot XS bands and then produced updated maps. Sixteen map units covering 12 vegetation types were recognized in the area based on both field works and satellite mapping. Halocnemum strobilaceum and Suaeda fruticosa vegetation types were the dominant types and Ephedra foliata, Salicornia europaea-Suaeda heterophylla vegetation types were the smallest. Vegetation coverage decreased sharply with the increase in salinity towards the coastal areas of the Persian Gulf. The highest vegetation coverage belonged to the riparian vegetation along the Mond River, which represents the northern boundary of the protected area. The location of vegetation types was studied on the separate soil and habitat diversity maps of the study area, which helped in final refinements of the vegetation map produced.

[Cross comparison of ASTER and Landsat ETM+ multispectral measurements for NDVI and SAVI vegetation indices].

Science.gov (United States)

Xu, Han-qiu; Zhang, Tie-jun

2011-07-01

The present paper investigates the quantitative relationship between the NDVI and SAVI vegetation indices of Landsat and ASTER sensors based on three tandem image pairs. The study examines how well ASTER sensor vegetation observations replicate ETM+ vegetation observations, and more importantly, the difference in the vegetation observations between the two sensors. The DN values of the three image pairs were first converted to at-sensor reflectance to reduce radiometric differences between two sensors, images. The NDVI and SAVI vegetation indices of the two sensors were then calculated using the converted reflectance. The quantitative relationship was revealed through regression analysis on the scatter plots of the vegetation index values of the two sensors. The models for the conversion between the two sensors, vegetation indices were also obtained from the regression. The results show that the difference does exist between the two sensors, vegetation indices though they have a very strong positive linear relationship. The study found that the red and near infrared measurements differ between the two sensors, with ASTER generally producing higher reflectance in the red band and lower reflectance in the near infrared band than the ETM+ sensor. This results in the ASTER sensor producing lower spectral vegetation index measurements, for the same target, than ETM+. The relative spectral response function differences in the red and near infrared bands between the two sensors are believed to be the main factor contributing to their differences in vegetation index measurements, because the red and near infrared relative spectral response features of the ASTER sensor overlap the vegetation "red edge" spectral region. The obtained conversion models have high accuracy with a RMSE less than 0.04 for both sensors' inter-conversion between corresponding vegetation indices.

Electronic prompts significantly increase response rates to postal questionnaires: a randomized trial within a randomized trial and meta-analysis.

Science.gov (United States)

Clark, Laura; Ronaldson, Sarah; Dyson, Lisa; Hewitt, Catherine; Torgerson, David; Adamson, Joy

2015-12-01

To assess the effectiveness of sending electronic prompts to randomized controlled trial participants to return study questionnaires. A "trial within a trial" embedded within a study determining the effectiveness of chronic obstructive pulmonary disease (DOC) screening on smoking cessation. Those participants taking part in DOC who provided a mobile phone number and/or an electronic mail address were randomized to either receive an electronic prompt or no electronic prompt to return a study questionnaire. The results were combined with two previous studies in a meta-analysis. A total of 437 participants were randomized: 226 to the electronic prompt group and 211 to the control group. A total of 285 (65.2%) participants returned the follow-up questionnaire: 157 (69.5%) in the electronic prompt group and 128 (60.7%) in the control group [difference 8.8%; 95% confidence interval (CI): -0.11%, 17.7%; P = 0.05]. The mean time to response was 23 days in the electronic prompt group and 33 days in the control group (hazard ratio = 1.27; 95% CI: 1.105, 1.47). The meta-analysis of all three studies showed an increase in response rate of 7.1% (95% CI: 0.8%, 13.3%). The use of electronic prompts increased response rates and reduces the time to response. Copyright © 2015 Elsevier Inc. All rights reserved.

Monitoring temporal Vegetation changes in Lao tropical forests

International Nuclear Information System (INIS)

Phompila, Chittana; Lewis, Megan; Clarke, Kenneth; Ostendorf, Bertram

2014-01-01

Studies on changes in vegetation are essential for understanding the interaction between humans and the environment. These studies provide key information for land use assessment, terrestrial ecosystem monitoring, carbon flux modelling and impacts of global climate change. The primary purpose of this study was to detect temporal vegetation changes in tropical forests in the southern part of Lao PDR from 2001-2012. The study investigated the annual vegetation phenological response of dominant land cover types across the study area and relationships to seasonal precipitation and temperature. Improved understanding of intra-annual patterns of vegetation variation was useful to detect longer term changes in vegetation. The breaks for additive season and trend (BFAST) approach was implemented to detect changes in these land cover types throughout the 2001-2012 period. We used the enhanced vegetation index (EVI) data from the Moderate Resolution Imaging Spectroradiometer (MODIS) (MOD13Q1 products) and monthly rainfall and temperature data obtained from the Meteorology and Hydrology Department, Ministry of Agriculture-Forestry, published by Lao National Statistical Centre in this research. EVI well documented the annual seasonal growth of vegetation and clearly distinguished the characteristic phenology of four different land use types; native forest, plantation, agriculture and mixed wooded/cleared area. Native forests maintained high EVI throughout the year, while plantations, wooded/cleared areas and agriculture showed greater inter-annual variation, with minimum EVI at the end of the dry season in April and maximum EVI in September-October, around two months after the wet season peak in rainfall. The BFAST analysis detected abrupt temporal changes in vegetation in the tropical forests, especially in a large conversion of mixed wooded/cleared area into plantation. Within the study area from 2001-2012 there has been an overall decreasing trend of vegetation cover for

A critical review on effects, tolerance mechanisms and management of cadmium in vegetables.

Science.gov (United States)

Rizwan, Muhammad; Ali, Shafaqat; Adrees, Muhammad; Ibrahim, Muhammad; Tsang, Daniel C W; Zia-Ur-Rehman, Muhammad; Zahir, Zahir Ahmad; Rinklebe, Jörg; Tack, Filip M G; Ok, Yong Sik

2017-09-01

Cadmium (Cd) accumulation in vegetables is an important environmental issue that threatens human health globally. Understanding the response of vegetables to Cd stress and applying management strategies may help to reduce the Cd uptake by vegetables. The aim of the present review is to summarize the knowledge concerning the uptake and toxic effects of Cd in vegetables and the different management strategies to combat Cd stress in vegetables. Leafy vegetables grown in Cd contaminated soils potentially accumulate higher concentrations of Cd, posing a threat to food commodities. The Cd toxicity decreases seed germination, growth, biomass and quality of vegetables. This reduces the photosynthesis, stomatal conductance and alteration in mineral nutrition. Toxicity of Cd toxicity also interferes with vegetable biochemistry causing oxidative stress and resulting in decreased antioxidant enzyme activities. Several management options have been employed for the reduction of Cd uptake and toxicity in vegetables. The exogenous application of plant growth regulators, proper mineral nutrition, and the use of organic and inorganic amendments might be useful for reducing Cd toxicity in vegetables. The use of low Cd accumulating vegetable cultivars in conjunction with insolubilizing amendments and proper agricultural practices might be a useful technique for reducing Cd exposure in the food chain. Copyright © 2017 Elsevier Ltd. All rights reserved.

Transmission System Vegetation Management Program. Draft Environmental Impact Statement

International Nuclear Information System (INIS)

1999-01-01

Bonneville is responsible for maintaining a network of 24,000 kilometers (km) or 15,000 miles (mi.) of electric transmission lines and 350 substations in a region of diverse vegetation. This vegetation can interfere with electric power flow, pose safety problems for Bonneville and the public, and interfere with their ability to maintain these facilities. They need to (1) keep vegetation away from the electric facilities; (2) increase their program efficiency and consistency; (3) review herbicide use (under increased public scrutiny); and (4) maximize the range of tools they can use while minimizing environmental impact (Integrated Vegetation Management). This DEIS establishes Planning Steps for managing vegetation for specific projects (to be tiered to this EIS). In addition to No Action (current practice), alternatives are presented for Rights-of-way, Electric Yards, and Non-electric Facilities (landscaping, work yards). Four vegetation control methods are analyzed: manual, mechanical, herbicide, and biological. Also evaluated are 24 herbicide active ingredients and 4 herbicide application techniques (spot, localized, broadcast, and aerial). For rights-of-way, they consider three sets of alternatives: alternative management approaches (time-driven or establishing low-growing plant communities); alternative method packages; and, if herbicides are in a methods package, alternative vegetation selections (noxious weeds, deciduous, or any vegetation). For electric yards, one herbicide-use alternative is considered. For non-electric facilities, two method package alternatives are considered. For rights-of-way, the environmentally preferred alternative(s) would use manual, mechanical, and biological control methods, as well as spot and localized herbicide applications for noxious and deciduous plant species; the BPA-preferred alternative(s) would add broadcast and aerial herbicide applications, and would use herbicides on any vegetation. Both would favor a management

Flowering does not decrease vegetative competitiveness of Lolium perenne

DEFF Research Database (Denmark)

Thiele, Jan; Bagger Jørgensen, Rikke; Hauser, Thure Pavlo

2009-01-01

as reduced flowering could free resources and increase productivity. But if so, less-flowering cultivars might be more competitive and invade natural swards. We tested for costs of sexual reproduction on vegetative propagation and competitiveness of the perennial grass Lolium perenne, one of the most...... treatments were successful in producing clones with largely differing degrees of flowering. However, we found no negative correlation between flowering and vegetative propagation and competitiveness. Early and strongly flowering southern provenances showed less clonal growth and higher mortality, but within...... provenances the response of clone diameter to flowering was positive or neutral. We conclude that investment of resources into flowering has no measurable costs on vegetative propagation and competitiveness of L. perenne. The apparent lack of costs of sexual reproduction could be explained by bet...

Serum markers of bone turnover change in response to depletion and repletion of fruit and vegetable intake in adults: A 28-wk single-arm experimental feeding intervention

Science.gov (United States)

Data from controlled intervention trials are lacking to support observational evidence suggesting a positive association between intake of fruit and vegetable (FV) and bone health. The objective of this study was to assess serum markers of bone turnover change in response to FV depletion and repleti...

Loblolly pine growth following operational vegetation management treatments compares favorably to that achieved in complete vegetation control research trials

Science.gov (United States)

Dwight K. Lauer; Harold E. Quicke

2010-01-01

Different combinations of chemical site prep and post-plant herbaceous weed control installed at three Upper Coastal Plain locations were compared in terms of year 3 loblolly (Pinus taeda L.) pine response to determine the better vegetation management regimes. Site prep treatments were different herbicide rates applied in either July or October. Site...

Computational micromechanics analysis of electron hopping and interfacial damage induced piezoresistive response in carbon nanotube-polymer nanocomposites

International Nuclear Information System (INIS)

Chaurasia, A K; Seidel, G D; Ren, X

2014-01-01

Carbon nanotube (CNT)-polymer nanocomposites have been observed to exhibit an effective macroscale piezoresistive response, i.e., change in macroscale resistivity when subjected to applied deformation. The macroscale piezoresistive response of CNT-polymer nanocomposites leads to deformation/strain sensing capabilities. It is believed that the nanoscale phenomenon of electron hopping is the major driving force behind the observed macroscale piezoresistivity of such nanocomposites. Additionally, CNT-polymer nanocomposites provide damage sensing capabilities because of local changes in electron hopping pathways at the nanoscale because of initiation/evolution of damage. The primary focus of the current work is to explore the effect of interfacial separation and damage at the nanoscale CNT-polymer interface on the effective macroscale piezoresistive response. Interfacial separation and damage are allowed to evolve at the CNT-polymer interface through coupled electromechanical cohesive zones, within a finite element based computational micromechanics framework, resulting in electron hopping based current density across the separated CNT-polymer interface. The macroscale effective material properties and gauge factors are evaluated using micromechanics techniques based on electrostatic energy equivalence. The impact of the electron hopping mechanism, nanoscale interface separation and damage evolution on the effective nanocomposite electrostatic and piezoresistive response is studied in comparison with the perfectly bonded interface. The effective electrostatic/piezoresistive response for the perfectly bonded interface is obtained based on a computational micromechanics model developed in the authors’ earlier work. It is observed that the macroscale effective gauge factors are highly sensitive to strain induced formation/disruption of electron hopping pathways, interface separation and the initiation/evolution of interfacial damage. (paper)

Enhanced vegetation growth peak and its key mechanisms

Science.gov (United States)

Huang, K.; Xia, J.; Wang, Y.; Ahlström, A.; Schwalm, C.; Huntzinger, D. N.; Chen, J.; Cook, R. B.; Fang, Y.; Fisher, J. B.; Jacobson, A. R.; Michalak, A.; Schaefer, K. M.; Wei, Y.; Yan, L.; Luo, Y.

2017-12-01

It remains unclear that whether and how the vegetation growth peak has been shifted globally during the past three decades. Here we used two global datasets of gross primary productivity (GPP) and a satellite-derived Normalized Difference Vegetation Index (NDVI) to characterize recent changes in seasonal peak vegetation growth. The attribution of changes in peak growth to their driving factors was examined with several datasets. We demonstrated that the growth peak of global vegetation has been linearly increasing during the past three decades. About 65% of this trend is evenly explained by the expanding croplands (21%), rising atmospheric [CO2] (22%), and intensifying nitrogen deposition (22%). The contribution of expanding croplands to the peak growth trend was substantiated by measurements from eddy-flux towers, sun-induced chlorophyll fluorescence and a global database of plant traits, all of which demonstrated that croplands have a higher photosynthetic capacity than other vegetation types. The contribution of rising atmospheric [CO2] and nitrogen deposition are consistent with the positive response of leaf growth to elevated [CO2] (25%) and nitrogen addition (8%) from 346 manipulated experiments. The positive effect of rising atmospheric [CO2] was also well captured by 15 terrestrial biosphere models. However, most models underestimated the contributions of land-cover change and nitrogen deposition, but overestimated the positive effect of climate change.

MARKET BASKET SURVEY FOR SOME PESTICIDES RESIDUES IN FRUITS AND VEGETABLES FROM GHANA

Directory of Open Access Journals (Sweden)

Crentsil Kofi Bempah

2012-12-01

Full Text Available A study was conducted to investigate the organochlorine, organophosphorus and synthetic pyrethroid pesticide residues in fruits and vegetables from markets in Ghana. For this purpose, a total of 309 fruits and vegetable samples, were collected and analyzed by gas chromatography with electron capture detector. The obtained results showed that the predominance of organochlorine followed by organophosphorus and synthetic pyrethroid pesticides in most of the analyzed samples. The detected concentrations of them were most significant in vegetable samples. The results obtained showed that 39.2 % of the fruits and vegetable samples analyzed contained no detectable level of the monitored pesticides, 51.0 % of the samples gave results with trace levels of pesticide residues below the maximum residue limit (MRL, while 9.8 % of the samples were above the MRL. The findings point to the urgent need to establish reliable monitoring programs for pesticides, so that any exceedance in concentration over environmental quality standards can be detected and appropriate actions taken.

[Responses of normalized difference vegetation index (NDVI) to precipitation changes on the grassland of Tibetan Plateau from 2000 to 2015.

Science.gov (United States)

Wang, Zhi Peng; Zhang, Xian Zhou; He, Yong Tao; Li, Meng; Shi, Pei Li; Zu, Jia Xing; Niu, Ben

2018-01-01

Precipitation change is an important factor in the inter-annual variation of grassland growth on the Tibetan Plateau. The total amount, distribution pattern and concentration time are three basic characteristics of precipitation change. The temporal and spatial characteristics of precipitation change were analyzed based on climate data of 145 meteorological stations on the Tibetan Plateau and nearby areas from 2000 to 2015. The total precipitation amount was characterized by annual precipitation, distribution pattern of precipitation during the year was characterized by improved precipitation concentration index (PCI), and precipitation centroid (PC) was defined to indicate the change in precipitation concentrated time. To better illustrate the response of grassland to precipitation change, vegetation growth status was characterized by the maximum value of normalized difference vegetation index (NDVI max ). Results indicated that the annual precipitation and PCI had an apparent gradient across the whole plateau and the latest PC occurred in the southern plateau. NDVI max of alpine shrub grassland was significantly correlated with the change of PCI,increased with even distribution of precipitation during growth period, and limited by the total annual precipitation. Alpine meadow did not show significantly correlations with these three indices. The inter-annual variability of NDVI max of steppe was controlled by both PCI and PC. NDVI max of alpine desert grassland was mainly controlled by annual precipitation. In addition to annual total amount of precipitation, the distribution characteristics of precipitation should be further considered when the influence of precipitation change on different types of vegetation on the Qinghai Tibet Plateau was studied.

Cruciferous vegetables and risk of colorectal neoplasms: a systematic review and meta-analysis.

Science.gov (United States)

Tse, Genevieve; Eslick, Guy D

2014-01-01

Evidence shows cruciferous vegetables exhibit chemoprotective properties, commonly attributed to their rich source of isothiocyanates. However, epidemiological data examining the association between cruciferous vegetable intake and colorectal neoplasms have been inconclusive. This meta-analysis examines the epidemiological evidence to characterize the association between cruciferous vegetable intake and risk of developing colorectal neoplasms. Thirty-three articles were included in the meta-analysis after a literature search of electronic databases. Subgroup analysis for individual cruciferae types (n = 8 studies) and GST polymorphism (n = 8 studies) were performed. Pooled adjusted odds ratios (ORs) comparing highest and lowest categories of dietary pattern scores were calculated. Results show a statistically significant inverse association between cruciferous vegetable intake and colon cancer [OR = 0.84; 95% confidence interval (CI): 0.72-0.98; P value heterogeneity colorectal (CRC) neoplasms (OR = 0.80; 95% CI: 0.65-0.99; P value heterogeneity = 0.02). Stratification by GST genotype reveals that the GSTT1 null genotype confers a reduction in CRC risk (OR = 0.78; 95% CI: 0.64-0.95; P value heterogeneity = 0.32). This study provides support to the hypothesis that cruciferous vegetable intake protects against cancer of the colon. This study also demonstrates the significance of gene-diet interactions and the importance of assessing individual cruciferous vegetables.

European Vegetation Archive (EVA): an integrated database of European vegetation plots

DEFF Research Database (Denmark)

Chytrý, M; Hennekens, S M; Jiménez-Alfaro, B

2015-01-01

vegetation- plot databases on a single software platform. Data storage in EVA does not affect on-going independent development of the contributing databases, which remain the property of the data contributors. EVA uses a prototype of the database management software TURBOVEG 3 developed for joint management......The European Vegetation Archive (EVA) is a centralized database of European vegetation plots developed by the IAVS Working Group European Vegetation Survey. It has been in development since 2012 and first made available for use in research projects in 2014. It stores copies of national and regional...... data source for large-scale analyses of European vegetation diversity both for fundamental research and nature conservation applications. Updated information on EVA is available online at http://euroveg.org/eva-database....

The influence of vegetation dynamics on anthropogenic climate change

Directory of Open Access Journals (Sweden)

U. Port

2012-11-01

Full Text Available In this study, vegetation–climate and vegetation–carbon cycle interactions during anthropogenic climate change are assessed by using the Earth System Model of the Max Planck Institute for Meteorology (MPI ESM that includes vegetation dynamics and an interactive carbon cycle. We assume anthropogenic CO₂ emissions according to the RCP 8.5 scenario in the time period from 1850 to 2120. For the time after 2120, we assume zero emissions to evaluate the response of the stabilising Earth System by 2300.

Our results suggest that vegetation dynamics have a considerable influence on the changing global and regional climate. In the simulations, global mean tree cover extends by 2300 due to increased atmospheric CO₂ concentration and global warming. Thus, land carbon uptake is higher and atmospheric CO₂ concentration is lower by about 40 ppm when considering dynamic vegetation compared to the static pre-industrial vegetation cover. The reduced atmospheric CO₂ concentration is equivalent to a lower global mean temperature. Moreover, biogeophysical effects of vegetation cover shifts influence the climate on a regional scale. Expanded tree cover in the northern high latitudes results in a reduced albedo and additional warming. In the Amazon region, declined tree cover causes a regional warming due to reduced evapotranspiration. As a net effect, vegetation dynamics have a slight attenuating effect on global climate change as the global climate cools by 0.22 K due to natural vegetation cover shifts in 2300.

Vegetated dune morphodynamics during recent stabilization of the Mu Us dune field, north-central China

Science.gov (United States)

Xu, Zhiwei; Mason, Joseph A.; Lu, Huayu

2015-01-01

The response of dune fields to changing environmental conditions can be better understood by investigating how changing vegetation cover affects dune morphodynamics. Significant increases in vegetation and widespread dune stabilization over the years 2000-2012 are evident in high-resolution satellite imagery of the Mu Us dune field in north-central China, possibly a lagged response to changing wind strength and temperature since the 1970s. These trends provide an opportunity to study how dune morphology changes with increasing vegetation stabilization. Vegetation expansion occurs mainly by expansion of pre-existing patches in interdunes. As vegetation spreads from interdunes onto surrounding dunes, it modifies their shapes in competition with wind-driven sand movement, primarily in three ways: 1) vegetation anchoring horns of barchans transforms them to parabolic dunes; 2) vegetation colonizes stoss faces of barchan and transverse dunes, resulting in lower dune height and an elongated stoss face, with shortening of barchan horns; and 3) on transverse dunes, the lee face is fixed by plants that survive sand burial. Along each of these pathways of stabilization, dune morphology tends to change from more barchanoid to more parabolic forms, but that transformation is not always completed before full stabilization. Artificial stabilization leads to an extreme case of "frozen" barchans or transverse dunes with original shapes preserved by rapid establishment of vegetation. Observations in the Mu Us dune field emphasize the point that vegetation growth and aeolian sand transport not only respond to external factors such as climate but also interact with each other. For example, some barchans lose sand mass during vegetation fixation, and actually migrate faster as they become smaller, and vegetation growth on a barchan's lower stoss face may alter sand transport over the dune in a way that favors more rapid stabilization. Conceptual models were generalized for the

Fruits, vegetables, and bladder cancer risk: a systematic review and meta-analysis.

Science.gov (United States)

Vieira, Ana R; Vingeliene, Snieguole; Chan, Doris S M; Aune, Dagfinn; Abar, Leila; Navarro Rosenblatt, Deborah; Greenwood, Darren C; Norat, Teresa

2015-01-01

Smoking is estimated to cause about half of all bladder cancer cases. Case-control studies have provided evidence of an inverse association between fruit and vegetable intake and bladder cancer risk. As part of the World Cancer Research/American Institute for Cancer Research Continuous Update Project, we conducted a systematic review and meta-analysis of prospective studies to assess the dose-response relationship between fruit and vegetables and incidence and mortality of bladder cancer. We searched PubMed up to December 2013 for relevant prospective studies. We conducted highest compared with lowest meta-analyses and dose-response meta-analyses using random effects models to estimate summary relative risks (RRs) and 95% confidence intervals (CIs), and used restricted cubic splines to examine possible nonlinear associations. Fifteen prospective studies were included in the review. The summary RR for an increase of 1 serving/day (80 g) were 0.97 (95% CI: 0.95-0.99) I(2)  = 0%, eight studies for fruits and vegetables, 0.97 (95% CI: 0.94-1.00, I(2)  = 10%, 10 studies) for vegetables and 0.98 (95% CI: 0.96-1.00, I(2)  = 0%, 12 studies) for fruits. Results were similar in men and women and in current, former and nonsmokers. Amongst fruits and vegetables subgroups, for citrus fruits the summary RR for the highest compared with the lowest intake was 0.87 (95% CI: 0.76-0.99, I(2)  = 0%, eight studies) and for cruciferous vegetables there was evidence of a nonlinear relationship (P = 0.001). The current evidence from cohort studies is not consistent with a role for fruits and vegetables in preventing bladder cancer. © 2014 The Authors. Cancer Medicine published by John Wiley & Sons Ltd.

Empirically Derived and Simulated Sensitivity of Vegetation to Climate Across Global Gradients of Temperature and Precipitation

Science.gov (United States)

Quetin, G. R.; Swann, A. L. S.

2017-12-01

Successfully predicting the state of vegetation in a novel environment is dependent on our process level understanding of the ecosystem and its interactions with the environment. We derive a global empirical map of the sensitivity of vegetation to climate using the response of satellite-observed greenness and leaf area to interannual variations in temperature and precipitation. Our analysis provides observations of ecosystem functioning; the vegetation interactions with the physical environment, across a wide range of climates and provide a functional constraint for hypotheses engendered in process-based models. We infer mechanisms constraining ecosystem functioning by contrasting how the observed and simulated sensitivity of vegetation to climate varies across climate space. Our analysis yields empirical evidence for multiple physical and biological mediators of the sensitivity of vegetation to climate as a systematic change across climate space. Our comparison of remote sensing-based vegetation sensitivity with modeled estimates provides evidence for which physiological mechanisms - photosynthetic efficiency, respiration, water supply, atmospheric water demand, and sunlight availability - dominate the ecosystem functioning in places with different climates. Earth system models are generally successful in reproducing the broad sign and shape of ecosystem functioning across climate space. However, this general agreement breaks down in hot wet climates where models simulate less leaf area during a warmer year, while observations show a mixed response but overall more leaf area during warmer years. In addition, simulated ecosystem interaction with temperature is generally larger and changes more rapidly across a gradient of temperature than is observed. We hypothesize that the amplified interaction and change are both due to a lack of adaptation and acclimation in simulations. This discrepancy with observations suggests that simulated responses of vegetation to

Examination of the spatial-response uniformity of a microchannel-plate detector using a pulsed high-voltage electron gun

International Nuclear Information System (INIS)

Alumot, D; Kroupp, E; Fisher, A

2014-01-01

In this paper we describe an alternative method to examine the spatial-response uniformity of a microchannel-plate (MCP) detector to a ∼ 1 ns pulse of soft x-rays. The examination was performed by illuminating the MCP surface with energetic electrons rather than with x-rays. It is shown that the MCP features similar, yet not identical, response to pulses of soft x-ray photons or energetic electrons, making such examinations much simpler and less expensive. The building of the electron-gun system is relatively easy and inexpensive, and in addition to verifying the spatial uniformity of the response of the MCP to incoming particles and radiation, it can be used to detect damaged areas on the detector. A comparison between the results obtained using the electron-gun with those obtained using a laser-produced-plasma x-ray source, demonstrating the reliability of the method, is presented

Global assessment of experimental climate warming on tundra vegetation: heterogeneity over space and time

Science.gov (United States)

Sarah C. Elmendorf; Gregory H.R. Henry; Robert D. Hollister; Robert G. Björk; Anne D. Bjorkman; Terry V. Callaghan; [and others] NO-VALUE; William Gould; Joel Mercado

2012-01-01

Understanding the sensitivity of tundra vegetation to climate warming is critical to forecasting future biodiversity and vegetation feedbacks to climate. In situ warming experiments accelerate climate change on a small scale to forecast responses of local plant communities. Limitations of this approach include the apparent site-specificity of results and uncertainty...

Response of vegetation to carbon dioxide - effect of elevated levels of CO{sub 2} on winter wheat under two moisture regimes

Energy Technology Data Exchange (ETDEWEB)

Chaudhuri, U.N.; Burnett, R.B.; Kanemasu, E.T.; Kirkham, M.B.

1987-12-31

This report deals with the second-year (1985-86) findings of an on going experiment with winter wheat (Triticum aestivum L.) at different carbon dioxide (CO{sub 2}) levels and under two moisture regimes. The results for the first year are given in the U.S. Department of Energy, Carbon Dioxide Research Division Response of Vegetation to Carbon Dioxide. The purpose of the second year`s experiment was to verify the results of 1984-85. However, based on the performance and the results of 1984-85 experiments, a few modifications were made.

Role of fruits and vegetables in adolescent cardiovascular health: a systematic review.

Science.gov (United States)

Collese, Tatiana Sadalla; Nascimento-Ferreira, Marcus Vinicius; de Moraes, Augusto César Ferreira; Rendo-Urteaga, Tara; Bel-Serrat, Silvia; Moreno, Luis A; Carvalho, Heráclito Barbosa

2017-05-01

Levels of fruit and vegetable consumption are low among adolescents, and the possible effect of this on cardiovascular health in this age group is undefined. The aim of this systematic review was to investigate the potential role of fruit and vegetable consumption in adolescent cardiovascular health. Six electronic databases (BioMed Central, MEDLINE, Web of Science, CINAHL, Scopus, PsycINFO) were searched from database inception to December 2015. The search strategy used the following sets of descriptors: adolescents; fruits and vegetables; cardiovascular risk indicators; cross-sectional and cohort studies. Potentially eligible articles were selected independently by 2 reviewers. Eleven articles meeting the inclusion criteria were included (10 cross-sectional, 1 cohort). The main reasons for study exclusion (n = 71) were misclassification of individuals as adolescents, an unspecified outcome that was incongruent with the definitions provided, and assessment of fruits and vegetables as part of a food pattern. Articles evaluated fruit and vegetable intake (separately, together, only vegetables, or with fruit juice) in diverse units, using food frequency questionnaires, 24-hour dietary recalls, and food records. One-third of the studies showed significant inverse associations of fruit and vegetable intake with systolic blood pressure, abdominal obesity, triglycerides, high-density lipoprotein cholesterol, and metabolic syndrome. The associations between fruit and vegetable consumption and indicators of cardiovascular risk in adolescents are inconsistent, likely because of heterogeneity in the methods used to assess and classify consumption and to define cardiovascular risk in adolescents. © The Author(s) 2017. Published by Oxford University Press on behalf of the International Life Sciences Institute. All rights reserved. For Permissions, please e-mail: journals.permissions@oup.com.

Order of 6 Jan 1988 on the treatment by ionizing radiation of dried fruits and vegetables

International Nuclear Information System (INIS)

1988-01-01

This Order specifies the conditions required for authorizing possession with a view to sale or putting on sale dried vegetables and dried fruit which have been irradiated for purposes of insect control through exposure to cobalt 60 or caesium 137 gamma radiation or to electron beams with an energy below or equal to 10 million electron-volts [fr

Vegetation Function and Physiology: Photosynthesis, Fluorescence and Non-photochemical Quenching (NPQ)

Science.gov (United States)

Zhang, Q.; Yao, T.

2017-12-01

Photosynthesis is a basic physiological function of vegetation that relies on PAR provided through photosynthetic pigments (mainly chlorophyll) for plant growth and biomass accumulation. Vegetation chlorophyll (chl) content and non-chlorophyll (non-chl) components vary with plant functional types (PFTs) and growing stages. The PAR absorbed by canopy chlorophyll (APARchl) is associated with photosynthesis (i.e., gross primary production, GPP) while the PAR absorbed by canopy non-chl components (APARnon-chl) is not associated with photosynthesis. Under non-optimal environmental conditions, vegetation is "stressed" and both photosynthesis (GPP) and light use efficiency are reduced, therefore, excess portions of APARchl are discarded as fluorescence or non-photochemical quenching (NPQ). The photochemical reflectance index (PRI) is a measurement related to NPQ. Both PRI and yield of solar induced chlorophyll fluorescence (SIFyield = SIF/APARchl) have been proposed as possible bio-indicators of LUEchl. We have successfully developed an algorithm to distinguish between chlorophyll and non-chl components of vegetation, and to retrieve fractional absorptions of PAR by chlorophyll (fAPARchl) and by non-chl components (fAPARnon-chl) with surface reflectance of MODIS bands 1 - 7. A method originally pioneered by Hanan et al. (2002) has been used to retrieve fAPAR for vegetation photosynthesis (fAPARPSN) at flux tower sites based on the light response curve of tower net ecosystem exchange (NEE) and incident PAR at low light intensity. We have also retrieved the PRI from MODIS data (bands 11 and 1) and have derived SIFyield with the Global Ozone Monitoring Experiment - 2 (GOME-2) SIF data. We find that fAPARPSN at flux tower sites matches well with site fAPARchl, and ratio fAPARnon-chl/fAPARchl varies largely. APARchl can explain >=78% variation in seasonal GPP . We disentangle the possible impact of fAPARchl on PRI from physiological stress response, disentangle the possible

Vegetation-mediated Climate Impacts on Historical and Future Ozone Air Quality

Science.gov (United States)

Tai, A. P. K.; Fu, Y.; Mickley, L. J.; Heald, C. L.; Wu, S.

2014-12-01

Changes in climate, natural vegetation and human land use are expected to significantly influence air quality in the coming century. These changes and their interactions have important ramifications for the effectiveness of air pollution control strategies. In a series of studies, we use a one-way coupled modeling framework (GEOS-Chem driven by different combinations of historical and future meteorological, land cover and emission data) to investigate the effects of climate-vegetation changes on global and East Asian ozone air quality from 30 years ago to 40 years into the future. We find that future climate and climate-driven vegetation changes combine to increase summertime ozone by 2-6 ppbv in populous regions of the US, Europe, East Asia and South Asia by year 2050, but including the interaction between CO2 and biogenic isoprene emission reduces the climate impacts by more than half. Land use change such as cropland expansion has the potential to either mostly offset the climate-driven ozone increases (e.g., in the US and Europe), or greatly increase ozone (e.g., in Southeast Asia). The projected climate-vegetation effects in East Asia are particularly uncertain, reflecting a less understood ozone production regime. We thus further study how East Asian ozone air quality has evolved since the early 1980s in response to climate, vegetation and emission changes to shed light on its likely future course. We find that warming alone has led to a substantial increase in summertime ozone in populous regions by 1-4 ppbv. Despite significant cropland expansion and urbanization, increased summertime leafiness of vegetation in response to warming and CO2 fertilization has reduced ozone by 1-2 ppbv, driven by enhanced ozone deposition dominating over elevated biogenic emission and partially offsetting the warming effect. The historical role of CO2-isoprene interaction in East Asia, however, remains highly uncertain. Our findings demonstrate the important roles of land cover

Electron irradiation response on Ge and Al-doped SiO 2 optical fibres

Science.gov (United States)

Yaakob, N. H.; Wagiran, H.; Hossain, I.; Ramli, A. T.; Bradley, D. A.; Hashim, S.; Ali, H.

2011-05-01

This paper describes the thermoluminescence response, sensitivity, stability and reproducibility of SiO 2 optical fibres with various electron energies and doses. The TL materials that comprise Al- and Ge-doped silica fibres were used in this experiment. The TL results are compared with those of the commercially available TLD-100. The doped SiO 2 optical fibres and TLD-100 are placed in a solid phantom and irradiated with 6, 9 and 12 MeV electron beams at doses ranging from 0.2 to 4.0 Gy using the LINAC at Hospital Sultan Ismail, Johor Bahru, Malaysia. It was found that the commercially available Al- and Ge-doped optical fibres have a linear dose-TL signal relationship. The intensity of TL response of Ge-doped fibre is markedly greater than that of the Al-doped fibre.

Electron irradiation response on Ge and Al-doped SiO2 optical fibres

International Nuclear Information System (INIS)

Yaakob, N.H.; Wagiran, H.; Hossain, I.; Ramli, A.T.; Bradley, D.A; Hashim, S.; Ali, H.

2011-01-01

This paper describes the thermoluminescence response, sensitivity, stability and reproducibility of SiO 2 optical fibres with various electron energies and doses. The TL materials that comprise Al- and Ge-doped silica fibres were used in this experiment. The TL results are compared with those of the commercially available TLD-100. The doped SiO 2 optical fibres and TLD-100 are placed in a solid phantom and irradiated with 6, 9 and 12 MeV electron beams at doses ranging from 0.2 to 4.0 Gy using the LINAC at Hospital Sultan Ismail, Johor Bahru, Malaysia. It was found that the commercially available Al- and Ge-doped optical fibres have a linear dose-TL signal relationship. The intensity of TL response of Ge-doped fibre is markedly greater than that of the Al-doped fibre.

Vegetation recovery in slash-pile scars following conifer removal in a grassland-restoration experiment

Science.gov (United States)

Charles B. Halpern; Joseph A. Antos; Liam M. Beckman

2014-01-01

A principal challenge to restoring tree-invaded grasslands is the removal of woody biomass. Burning of slash piles to reduce woody residues from forest restoration practices generates intense, prolonged heating, with adverse effects on soils and vegetation. In this study, we examined vegetation responses to pile burning following tree removal from conifer-invaded...

The impact of geoengineering on vegetation in experiment G1 of the Geoengineering Model Intercomparison Project

Science.gov (United States)

Irvine, Peter; Glienke, Susanne; Lawrence, Mark

2015-04-01

Solar Radiation Management (SRM) has been proposed as a means to partly counteract global warming. The Geoengineering Model Intercomparison Project (GeoMIP) simulated the climate consequences of a number of SRM techniques, but the effects on vegetation have not yet been thoroughly studied. Here, the vegetation response to the idealized GeoMIP G1 experiment is analyzed, in which a reduction of the solar constant counterbalances the radiative effects of quadrupled atmospheric CO2 concentrations; the results from eight fully coupled earth system models (ESMs) are included. For most models and regions, changes in net primary productivity (NPP) are dominated by the increase in CO2, via the CO2 fertilization effect. As SRM will lower temperatures, in high latitudes this will reverse gains in NPP from the lifting of temperature limitations. In low latitudes this cooling relative to the 4xCO2 simulation decreases plant respiration whilst having little effect on gross primary productivity, increasing NPP. Despite reductions in precipitation in most regions in response to SRM, runoff and NPP increase in many regions including those previously highlighted as potentially being at risk of drought under SRM. This is due to simultaneous reductions in evaporation and increases in water use efficiency by plants due to higher CO2 concentrations. The relative differences between models in the vegetation response are substantially larger than the differences in their climate responses. The largest differences between models are for those with and without a nitrogen-cycle, with a much smaller CO2 fertilization effect for the former. These results suggest that until key vegetation processes are integrated into ESM predictions, the vegetation response to SRM will remain highly uncertain.

Post-fire vegetation recovery in Portugal based ewline on spot/vegetation data

Directory of Open Access Journals (Sweden)

C. Gouveia

2010-04-01

Full Text Available A procedure is presented that allows identifying large burned scars and the monitoring of vegetation recovery in the years following major fire episodes. The procedure relies on 10-day fields of Maximum Value Composites of Normalized Difference Vegetation Index (MVC-NDVI, with a 1 km×1 km spatial resolution obtained from the VEGETATION instrument. The identification of fire scars during the extremely severe 2003 fire season is performed based on cluster analysis of NDVI anomalies that persist during the vegetative cycle of the year following the fire event. Two regions containing very large burned scars were selected, located in Central and Southwestern Portugal, respectively, and time series of MVC-NDVI analysed before the fire events took place and throughout the post-fire period. It is shown that post-fire vegetation dynamics in the two selected regions may be characterised based on maps of recovery rates as estimated by fitting a monoparametric model of vegetation recovery to MVC-NDVI data over each burned scar. Results indicated that the recovery process in the region located in Central Portugal is mostly related to fire damage rather than to vegetation density before 2003, whereas the latter seems to have a more prominent role than vegetation conditions after the fire episode, e.g. in the case of the region in Southwestern Portugal. These differences are consistent with the respective predominant types of vegetation. The burned area located in Central Portugal is dominated by Pinus Pinaster whose natural regeneration crucially depends on the destruction of seeds present on the soil surface during the fire, whereas the burned scar in Southwestern Portugal was populated by Eucalyptus that may quickly re-sprout from buds after fire. Besides its simplicity, the monoparametric model of vegetation recovery has the advantage of being easily adapted to other low-resolution satellite data, as well as to other types of vegetation

Fine-scale patterns of vegetation assembly in the monitoring of changes in coastal sand-dune landscapes

Directory of Open Access Journals (Sweden)

J. Honrado

2010-02-01

Full Text Available Understanding dune ecosystem responses to multi-scale environmental changes can provide the framework for reliable forecasts and cost-efficient protocols for detecting shifts in prevailing coastal dynamics. Based on the hypothesis that stress and disturbance interact as primary community controls in coastal dunes, we studied the fine-scale floristic assembly of foredune vegetation, in its relation to topography, along regional and local environmental gradients in the 200 km long coastline of northern Portugal, encompassing a major biogeographic transition in western Europe. Thirty topographic profiles perpendicular to the shoreline were recorded at ten sites along the regional climate gradient, and vegetation was sampled by recording the frequency of plant species along those profiles. Quantitative topographic attributes of vegetated dune profiles (e.g. length or height exhibited wide variations relatable to differences in prevailing coastal dynamics. Metrics of taxonomic diversity (e.g. total species richness and its additive beta component and of the functional composition of vegetation were highly correlated to attributes of dune topography. Under transgressive dynamics, vegetation profiles have fewer species, increased dominance, lower turnover rates, and lower total vegetation cover. These changes may drive a decrease in structural and functional diversity, with important consequences for resistance, resilience and other ecosystem properties. Moreover, differences in both vegetation assembly (in meta-stable dunes and response to increased disturbance (in eroding dunes between distinct biogeographic contexts highlight a possible decline in facilitation efficiency under extreme physical stress (i.e. under Mediterranean climate and support the significance of functional approaches in the study of local ecosystem responses to disturbance along regional gradients. Our results strongly suggest that assessing fine-scale community assembly can

Detecting inter-annual variations in the phenology of evergreen conifers using long-term MODIS vegetation index time series.

OpenAIRE

Ulsig, Laura

2016-01-01

Long-term observations of vegetation phenology can be used to monitor the response of terrestrial ecosystems to climate change. Satellite remote sensing provides the most efficient means to observe phenological events through time series analysis of vegetation indices such as the Normalised Difference Vegetation Index (NDVI). This study investigates the potential of the Photochemical Reflectance Index (PRI), which has been linked to vegetation light use efficiency, to improve the accuracy of ...

Shared responsibility for managing electronic waste: A case study of Maine, USA

International Nuclear Information System (INIS)

Wagner, Travis P.

2009-01-01

Based on high disposal and low recycling rates of electronic waste (e-waste) and continued exportation to developing countries, reliance on municipal responsibility for e-waste management has been unsuccessful in the United States. This case study examines Maine's program, which was the first US state to mandate producer responsibility for recycling household e-waste. Maine's program established a shared cost responsibility among producers, municipalities, and consumers. The study found that Maine's program resulted in a significant reduction in disposal and a corresponding increase in environmentally sound recycling. In the first 3 years of the program, 6.406 million kg of household e-waste was collected and recycled for a population of 1.32 million. The new program, implemented in 2006, increased the number of e-waste items collected and recycled by 108% in the first year, 170% in the second year, and 221% in the third year. The program decreased direct economic costs to municipalities and households because of the shared cost approach and for the first time established costs for producers. There was no empirical evidence indicating that producers have or will improve the recyclability of electronic products to reduce recycling costs. While other weaknesses were that found potentially limit the adoption of Maine's program, its positive aspects warrant consideration by other governments.

Optical Response of Warm Dense Matter Using Real-Time Electron Dynamics

Science.gov (United States)

Baczewski, Andrew; Shulenburger, Luke; Desjarlais, Michael; Magyar, Rudolph

2014-03-01

The extreme temperatures and solid-like densities in warm dense matter present a unique challenge for theory, wherein neither conventional models from condensed matter nor plasma physics capture all of the relevant phenomenology. While Kubo-Greenwood DFT calculations have proven capable of reproducing optical properties of WDM, they require a significant number of virtual orbitals to reach convergence due to their perturbative nature. Real-time TDDFT presents a complementary framework with a number of computationally favorable properties, including reduced cost complexity and better scalability, and has been used to reproduce the optical response of finite and ordered extended systems. We will describe the use of Ehrenfest-TDDFT to evolve coupled electron-nuclear dynamics in WDM systems, and the subsequent evaluation of optical response functions from the real-time electron dynamics. The advantages and disadvantages of this approach will be discussed relative to the current state-of-the-art. Sandia National Laboratories is a multi-program laboratory managed and operated by Sandia Corporation, a wholly owned subsidiary of Lockheed Martin Corporation, for the U.S. Department of Energy's National Security Administration under contract DE-AC04-94AL85000.

Past and future effects of climate change on spatially heterogeneous vegetation activity in China

Science.gov (United States)

Gao, Jiangbo; Jiao, Kewei; Wu, Shaohong; Ma, Danyang; Zhao, Dongsheng; Yin, Yunhe; Dai, Erfu

2017-07-01

Climate change is a major driver of vegetation activity but its complex ecological relationships impede research efforts. In this study, the spatial distribution and dynamic characteristics of climate change effects on vegetation activity in China from the 1980s to the 2010s and from 2021 to 2050 were investigated using a geographically weighted regression (GWR) model. The GWR model was based on combined datasets of satellite vegetation index, climate observation and projection, and future vegetation productivity simulation. Our results revealed that the significantly positive precipitation-vegetation relationship was and will be mostly distributed in North China. However, the regions with temperature-dominated distribution of vegetation activity were and will be mainly located in South China. Due to the varying climate features and vegetation cover, the spatial correlation between vegetation activity and climate change may be altered. There will be different dominant climatic factors for vegetation activity distribution in some regions such as Northwest China, and even opposite correlations in Northeast China. Additionally, the response of vegetation activity to precipitation will move southward in the next three decades. In contrast, although the high warming rate will restrain the vegetation activity, precipitation variability could modify hydrothermal conditions for vegetation activity. This observation is exemplified in the projected future enhancement of vegetation activity in the Tibetan Plateau and weakened vegetation activity in East and Middle China. Furthermore, the vegetation in most parts of North China may adapt to an arid environment, whereas in many southern areas, vegetation will be repressed by water shortage in the future.

Rapid response of alpine timberline vegetation to the Younger Dryas climate oscillation in the Colorado Rocky Mountains, USA

International Nuclear Information System (INIS)

Reasoner, M.A.; Jodry, M.A.

2000-01-01

Paleobotanical records from two high-altitude (>3,300 m) sites in Colorado show a clear and immediate response to the Younger Dryas climate oscillation. The Black Mountain Lake and Sky Pond records indicate that alpine timberline migrated upslope to near-modern elevations during the late Bolling-Allerod (13.6--12.9 ka). Subsequent declines in arboreal pollen percentages and accumulation rates during the Younger Dryas interval (12.9--11.7 ka) reflect a downslope displacement of the alpine timberline ecotone of 60--120 m in elevation. This change translates to a cooling of summer temperature by ∼0.4--0.9 C and is consistent with proposed Younger Dryas advances of alpine glaciers in the Rocky Mountains to positions close to Little Ice Age maxima. Alpine timberline readvanced upslope to elevations above both sites between 11.7 and 11.4 ka. The concomitant response of temperature-sensitive alpine timberline vegetation in Colorado and late-glacial changes in North Atlantic thermohaline circulating implicates a rapid, widespread atmospheric transmission of the Younger Dryas climate oscillation

Rapid response of alpine timberline vegetation to the Younger Dryas climate oscillation in the Colorado Rocky Mountains, USA

Energy Technology Data Exchange (ETDEWEB)

Reasoner, M.A.; Jodry, M.A.

2000-01-01

Paleobotanical records from two high-altitude (>3,300 m) sites in Colorado show a clear and immediate response to the Younger Dryas climate oscillation. The Black Mountain Lake and Sky Pond records indicate that alpine timberline migrated upslope to near-modern elevations during the late Bolling-Allerod (13.6--12.9 ka). Subsequent declines in arboreal pollen percentages and accumulation rates during the Younger Dryas interval (12.9--11.7 ka) reflect a downslope displacement of the alpine timberline ecotone of 60--120 m in elevation. This change translates to a cooling of summer temperature by {approximately}0.4--0.9 C and is consistent with proposed Younger Dryas advances of alpine glaciers in the Rocky Mountains to positions close to Little Ice Age maxima. Alpine timberline readvanced upslope to elevations above both sites between 11.7 and 11.4 ka. The concomitant response of temperature-sensitive alpine timberline vegetation in Colorado and late-glacial changes in North Atlantic thermohaline circulating implicates a rapid, widespread atmospheric transmission of the Younger Dryas climate oscillation.

Detecting Historical Vegetation Changes in the Dunhuang Oasis Protected Area Using Landsat Images

Directory of Open Access Journals (Sweden)

Xiuxia Zhang

2017-09-01

Full Text Available Abstract: Given its proximity to an artificial oasis, the Donghu Nature Reserve in the Dunhuang Oasis has faced environmental pressure and vegetation disturbances in recent decades. Satellite vegetation indices (VIs can be used to detect such changes in vegetation if the satellite images are calibrated to surface reflectance (SR values. The aim of this study was to select a suitable VI based on the Landsat Climate Data Record (CDR products and the absolute radiation-corrected results of Landsat L1T images to detect the spatio-temporal changes in vegetation for the Donghu Reserve during 1986–2015. The results showed that the VI difference (ΔVI images effectively reduced the changes in the source images. Compared with the other VIs, the soil-adjusted vegetation index (SAVI displayed greater robustness to atmospheric effects in the two types of SR images and was more responsive to vegetation changes caused by human factors. From 1986 to 2015, the positive changes in vegetation dominated the overall change trend, with changes in vegetation in the reserve decreasing during 1990–1995, increasing until 2005–2010, and then decreasing again. The vegetation changes were mainly distributed at the edge of the artificial oasis outside the reserve. The detected changes in vegetation in the reserve highlight the increased human pressure on the reserve.

Hydraulic and Vegetative Models of Historic Environmental Conditions Isolate the Role of Riparian Vegetation in Inducing Channel Change

Science.gov (United States)

Manners, R.; Schmidt, J. C.; Wheaton, J. M.

2011-12-01

elevation of tamarisk-dominated stands in the study reaches allowed us to temporally and spatially scale the vegetative hydraulic roughness. Flood-event hydrology and sediment rating curves were derived from nearby USGS stream gages. The two flood events, while similar in flood peak magnitude, had strikingly different geomorphic effects. The 1984 flood left extensive fine-grained deposits in the study areas, but the 2011 flood caused significant scour as well as fill, resulting in significant areas of erosion as well as deposition. One reason for this finding is the difference in flood duration. However, other observed differences appear to be a result of the temporal differences in distribution and density of tamarisk stands wherein the density of riparian vegetation increased greatly between 1984 and 2011 . Our integration of sedimentologic, topographic, and vegetation stand structure data with hydraulic modeling also makes it possible to anticipate the style and magnitude of future channel changes in response to future changes in the flow regime, sediment supply, and/or riparian vegetation communities composition.

Responses of vegetation and soil microbial communities to warming and simulated herbivory in a subarctic heath

DEFF Research Database (Denmark)

Rinnan, Riikka; Stark, Sari; Tolvanen, Anne

2009-01-01

Climate warming increases the cover of deciduous shrubs in arctic ecosystems and herbivory is also known to have a strong influence on the biomass and composition of vegetation. However, research combining herbivory with warming is largely lacking. Our study describes how warming and simulated...... setup of the International Tundra Experiment (ITEX). Wounding of the dominant deciduous dwarf shrub Vaccinium myrtillus L. to simulate herbivory was carried out annually. We measured vegetation cover in 2003 and 2007, soil nutrient concentrations in 2003 and 2006, soil microbial respiration in 2003...... and herbivory. 6 Synthesis. Our results show that warming increases the cover of V. myrtillus, which seems to enhance the nutrient sink strength of vegetation in the studied ecosystem. However, herbivory partially negates the effect of warming on plant N uptake and interacts with the effect of warming...

Suppression of vegetation in LANDSAT ETM+ remote sensing images

Science.gov (United States)

Yu, Le; Porwal, Alok; Holden, Eun-Jung; Dentith, Michael

2010-05-01

value and scaling all pixels at each vegetation index level by an amount that shifts the curve to the target digital number (DN). The main drawback of their algorithm is severe distortions of the DN values of non-vegetated areas, a suggested solution is masking outliers such as cloud, water, etc. We therefore extend this algorithm by masking non-vegetated areas. Our algorithm comprises the following three steps: (1) masking of barren or sparsely vegetated areas using a threshold based on a vegetation index that is calculated after atmosphere correction (dark pixel correction and ACTOR were compared) in order to conserve their original spectral information through the subsequent processing; (2) applying Crippen and Blom's forced invariance algorithm to suppress the spectral response of vegetation only in vegetated areas; and (3) combining the processed vegetated areas with the masked barren or sparsely vegetated areas followed by histogram equalization to eliminate the differences in color-scales between these two types of areas, and enhance the integrated image. The output images of both study areas showed significant improvement over the original images in terms of suppression of vegetation reflectance and enhancement of the underlying geological information. The processed images show clear banding, probably associated with lithological variations in the underlying rock formations. The colors of non-vegetated pixels are distorted in the unmasked results but in the same location the pixels in the masked results show regions of higher contrast. We conclude that the algorithm offers an effective way to enhance geological information in LANDSAT TM/ETM+ images of terrains with significant vegetation cover. It is also suitable to other multispectral satellite data have bands in similar wavelength regions. In addition, an application of this method to hyperspectral data may be possible as long as it can provide the vegetation band ratios.

The East Bay Vegetation Management Consortium:\\ta subregional approach to resource management and planning

Science.gov (United States)

Tony Acosta

1995-01-01

Formed in response to the October 20, 1991, Oakland/Berkeley hills firestorm, the East Bay Vegetation Management Consortium (EBVMC) is a voluntary association of public agencies concerned with vegetation management and planning related to fire hazard reduction in the Oakland/ Berkeley hills. To date, a total of nine agencies are participating in the EBVMC, including...

Tropical climate and vegetation cover during Heinrich event 1: Simulations with coupled climate vegetation models

OpenAIRE

Handiani, Dian Noor

2012-01-01

This study focuses on the climate and vegetation responses to abrupt climate change in the Northern Hemisphere during the last glacial period. Two abrupt climate events are explored: the abrupt cooling of the Heinrich event 1 (HE1), followed by the abrupt warming of the Bølling-Allerød interstadial (BA). These two events are simulated by perturbing the freshwater balance of the Atlantic Ocean, with the intention of altering the Atlantic Meridional Overturning Circulation (AMOC) and also of in...

Modeling of the response under radiation of electronic dosemeters

International Nuclear Information System (INIS)

Menard, S.

2003-01-01

The simulation with with calculation codes the interactions and the transport of primary and secondary radiations in the detectors allows to reduce the number of developed prototypes and the number of experiments under radiation. The simulation makes possible the determination of the response of the instrument for exposure configurations more extended that these ones of references radiations produced in laboratories. The M.C.N.P.X. allows to transport, over the photons, electrons and neutrons, the charged particles heavier than the electrons and to simulate the radiation - matter interactions for a certain number of particles. The present paper aims to present the interest of the use of the M.C.N.P.X. code in the study, research and evaluation phases of the instrumentation necessary to the dosimetry monitoring. To do that the presentation gives the results of the modeling of a prototype of a equivalent tissue proportional counter (C.P.E.T.) and of the C.R.A.M.A.L. ( radiation protection apparatus marketed by the Eurisys Mesures society). (N.C.)

Genetic taste markers and preferences for vegetables and fruit of female breast care patients.

Science.gov (United States)

Drewnowski, A; Henderson, S A; Hann, C S; Berg, W A; Ruffin, M T

2000-02-01

To explore links between genetic responsiveness to the bitter taste of 6-n-propylthiouracil (PROP) and self-reported preferences for vegetables and fruit of female breast care patients. PROP tasting was defined by detection thresholds and by perceived bitterness and hedonic ratings for PROP solutions. Nontasters, medium tasters, and supertasters were identified by their PROP thresholds and by the ratio of perceived bitterness of PROP to the perceived saltiness of sodium chloride solutions. Subjects rated preferences for vegetables and fruit using 9-point category scales. A clinical sample of 170 patients with newly diagnosed breast cancer and 156 cancer-free control subjects were recruited from the University of Michigan Breast Care Center. Principal components factor analysis, one-way analyses of variance, and Pearson correlations and chi 2 tests were used to analyze taste and food preference data. Genetic responsiveness to PROP was associated with lower acceptance of cruciferous and selected green and raw vegetables (P cancer prevention that emphasize consumption of cruciferous vegetables and bitter salad greens. Alternatively, PROP-sensitive women may seek to reduce bitter taste by adding fat, sugar, or salt.

Fruits and vegetables consumption and risk of stroke: a meta-analysis of prospective cohort studies.

Science.gov (United States)

Hu, Dan; Huang, Junqian; Wang, Yuchun; Zhang, Dongfeng; Qu, Yan

2014-06-01

We conducted a meta-analysis to summarize evidence from prospective cohort studies about the association of fruits and vegetables consumption with the risk of stroke. Pertinent studies were identified by a search of Embase and PubMed databases to January 2014. Study-specific relative risks with 95% confidence intervals were pooled using a random-effects model. Dose-response relationship was assessed by restricted cubic spline. Twenty prospective cohort studies were included, involving 16 981 stroke events among 760 629 participants. The multivariable relative risk (95% confidence intervals) of stroke for the highest versus lowest category of total fruits and vegetables consumption was 0.79 (0.75-0.84), and the effect was 0.77 (0.71-0.84) for fruits consumption and 0.86 (0.79-0.93) for vegetables consumption. Subgroup and meta-regression showed that the inverse association of total fruits and vegetables consumption with the risk of stroke was consistent in subgroup analysis. Citrus fruits, apples/pears, and leafy vegetables might contribute to the protection. The linear dose-response relationship showed that the risk of stroke decreased by 32% (0.68 [0.56-0.82]) and 11% (0.89 [0.81-0.98]) for every 200 g per day increment in fruits consumption (P for nonlinearity=0.77) and vegetables consumption (P for nonlinearity=0.62), respectively. Fruits and vegetables consumption are inversely associated with the risk of stroke. © 2014 American Heart Association, Inc.

Morphology of Ichthyophonus hoferi assessed by light and scanning electron microscopy

DEFF Research Database (Denmark)

Spanggaard, Bettina; Huss, Hans Henrik; Bresciani, J.

1995-01-01

The morphology of Ichthyophonus hoferi in vitro at pH 3.5 and 7.0 is described using light and scanning electron microscopy. Only vegetative growth was observed. At pH 3.5, hyphal growth was seen. The hyphae of I. hoferi are characterized by evacuated hyphal walls with the cytoplasm migrating......-walled multinucleate spores in the fish stomach as a response to the low pH. The hyphae then penetrate the digestive tract and rupture when they reach a blood vessel (neutral pH), whereby uni- and binucleate bodies and/or amoeboid bodies are released. The small cells are transported in the blood vessels and spread...

Vegetation dynamics at the upper elevational limit of vascular plants in Himalaya.

Science.gov (United States)

Dolezal, Jiri; Dvorsky, Miroslav; Kopecky, Martin; Liancourt, Pierre; Hiiesalu, Inga; Macek, Martin; Altman, Jan; Chlumska, Zuzana; Rehakova, Klara; Capkova, Katerina; Borovec, Jakub; Mudrak, Ondrej; Wild, Jan; Schweingruber, Fritz

2016-05-04

A rapid warming in Himalayas is predicted to increase plant upper distributional limits, vegetation cover and abundance of species adapted to warmer climate. We explored these predictions in NW Himalayas, by revisiting uppermost plant populations after ten years (2003-2013), detailed monitoring of vegetation changes in permanent plots (2009-2012), and age analysis of plants growing from 5500 to 6150 m. Plant traits and microclimate variables were recorded to explain observed vegetation changes. The elevation limits of several species shifted up to 6150 m, about 150 vertical meters above the limit of continuous plant distribution. The plant age analysis corroborated the hypothesis of warming-driven uphill migration. However, the impact of warming interacts with increasing precipitation and physical disturbance. The extreme summer snowfall event in 2010 is likely responsible for substantial decrease in plant cover in both alpine and subnival vegetation and compositional shift towards species preferring wetter habitats. Simultaneous increase in summer temperature and precipitation caused rapid snow melt and, coupled with frequent night frosts, generated multiple freeze-thaw cycles detrimental to subnival plants. Our results suggest that plant species responses to ongoing climate change will not be unidirectional upward range shifts but rather multi-dimensional, species-specific and spatially variable.

Organic seed treatment of vegetables to prevent seedborne diseases

NARCIS (Netherlands)

Spadaro, D.; Herforth-Rahmé, J.; Wolf, van der J.M.

2017-01-01

Seedborne pathogens of vegetables are responsible for the re-emergence of diseases of the past, as well as the introduction of diseases into new geographical areas. Seed treatment can be used to eradicate seedborne pathogens or to protect from soilborne pathogens. The European Commission Regulation

Detecting Inter-Annual Variations in the Phenology of Evergreen Conifers Using Long-Term MODIS Vegetation Index Time Series

OpenAIRE

Ulsig, Laura; Nichol, Caroline J.; Huemmrich, Karl F.; Landis, David R.; Middleton, Elizabeth M.; Lyapustin, Alexei I.; Mammarella, Ivan; Levula, Janne; Porcar-Castell, Albert

2017-01-01

Long-term observations of vegetation phenology can be used to monitor the response of terrestrial ecosystems to climate change. Satellite remote sensing provides the most efficient means to observe phenological events through time series analysis of vegetation indices such as the Normalized Difference Vegetation Index (NDVI). This study investigates the potential of a Photochemical Reflectance Index (PRI), which has been linked to vegetation light use efficiency, to improve the accuracy of MO...

Method of producing vegetable puree

DEFF Research Database (Denmark)

2004-01-01

A process for producing a vegetable puree, comprising the sequential steps of: a)crushing, chopping or slicing the vegetable into pieces of 1 to 30 mm; b) blanching the vegetable pieces at a temperature of 60 to 90°C; c) contacted the blanched vegetable pieces with a macerating enzyme activity; d......) blending the macerated vegetable pieces and obtaining a puree....

Estimating vegetation dryness to optimize fire risk assessment with spot vegetation satellite data in savanna ecosystems

Science.gov (United States)

Verbesselt, J.; Somers, B.; Lhermitte, S.; van Aardt, J.; Jonckheere, I.; Coppin, P.

2005-10-01

The lack of information on vegetation dryness prior to the use of fire as a management tool often leads to a significant deterioration of the savanna ecosystem. This paper therefore evaluated the capacity of SPOT VEGETATION time-series to monitor the vegetation dryness (i.e., vegetation moisture content per vegetation amount) in order to optimize fire risk assessment in the savanna ecosystem of Kruger National Park in South Africa. The integrated Relative Vegetation Index approach (iRVI) to quantify the amount of herbaceous biomass at the end of the rain season and the Accumulated Relative Normalized Difference vegetation index decrement (ARND) related to vegetation moisture content were selected. The iRVI and ARND related to vegetation amount and moisture content, respectively, were combined in order to monitor vegetation dryness and optimize fire risk assessment in the savanna ecosystems. In situ fire activity data was used to evaluate the significance of the iRVI and ARND to monitor vegetation dryness for fire risk assessment. Results from the binary logistic regression analysis confirmed that the assessment of fire risk was optimized by integration of both the vegetation quantity (iRVI) and vegetation moisture content (ARND) as statistically significant explanatory variables. Consequently, the integrated use of both iRVI and ARND to monitor vegetation dryness provides a more suitable tool for fire management and suppression compared to other traditional satellite-based fire risk assessment methods, only related to vegetation moisture content.

Phosphorene under strain:electronic, mechanical and piezoelectric responses

Science.gov (United States)

Drissi, L. B.; Sadki, S.; Sadki, K.

2018-01-01

Structural, electronic, elastic and piezoelectric properties of pure phosphorene under in-plane strain are investigated using first-principles calculations based on density functional theory. The two critical yielding points are determined along armchair and zigzag directions. It is shown that the buckling, the band gap and the charge transfer can be controlled under strains. A semiconductor to metallic transition is observed in metastable region. Polar plots of Young's modulus, Poisson ratio, sound velocities and Debye temperature exhibit evident anisotropic feature of phosphorene and indicate auxetic behavior for some angles θ. Our calculations show also that phosphorene has both in-plane and out-of-plane piezoelectric responses comparable to known 2D materials. The findings of this work reveal the great potential of pure phosphorene in nanomechanical applications.

The role of vegetation in shaping dune morphology

Science.gov (United States)

Duran Vinent, O.; Moore, L. J.; Young, D.

2012-12-01

. Consistent with field observations, we find that basic dune morphology is primarily determined by grass species, with linear or hummocky dunes being built by some species, while others may prevent dune formation. We also find that the evolution of coastal dune morphology is controlled by at least two bio-geomorphic couplings: (1) between vegetation growth and sand transport, which leads to a positive feedback for dune growth, as certain beach grasses maximize growth under sand accretion, which means that an ever denser vegetation implies an ever higher accretion rate; and (2) between vegetation growth and shoreline position through the sand influx. While the first coupling is responsible for dune formation, the second one determines when dunes stop growing and thus controls final dune size. This is particularly relevant for accreting/eroding coastlines where we find that dune size, and thus coastal protection, is maximized for relatively small accretion rates while larger accretion rates lead to formation of a new, smaller dune ridge at the beach.

Renewable energy from vegetation; Les energies renouvelables d'origine vegetale

Energy Technology Data Exchange (ETDEWEB)

Sales, C. [Centre francais de cooperation international en recherche agronomique pour le developpement (France)

2009-07-15

Currently, vegetation accounts for 3 major types of energy sources, notably woody biomass, starches and vegetable oils. Bio-ethanol and biodiesel is produced from the fermentation of starches, such as sugar cane, beet sugar, sorghum, corn and potatoes. Biofuels can be produced from palm tree oil, coconut oil , soya oil, sunflower oil or any type of vegetable based oil. This article discussed energy efficiency issues and the environmental impact of developing these energies. In general, the lower energy efficiency of the starches can be attributed to the enzymes responsible for the catalysis. The article also reviewed the thermochemistry and energy efficiency regarding second generation fuels. It also discussed the burning of biomass, including woody biomass, forest waste and agricultural waste. 1 ref., 2 figs.

Designing and implementing an electronic dashboard for disease outbreaks response - Case study of the 2013-2014 Somalia Polio outbreak response dashboard.

Science.gov (United States)

Kamadjeu, Raoul; Gathenji, Caroline

2017-01-01

In April 2013, a case of wild polio virus (WPV) was detected in the Somalia capital Mogadishu. This inaugurated what is now referred to as the 2013-2014 Horn of Africa Polio outbreak with cases reported in Somalia, Kenya and Ethiopia. By the notification of the last polio case in August 2014, 223 cases of WPV had been reported in Somalia, Kenya and Ethiopia of which 199 in Somalia alone. The outbreak response required timely exchange of information between the outbreak response coordination unit (in Nairobi) and local staff located in multiple locations inside the country. The need to track and timely respond to information requests, to satisfy the information/data needs of polio partners and to track key outbreak response performance indicators dictated the need to urgently set up an online dashboard. The Somalia Polio Room dashboard provided a graphical display of the polio outbreak data to track progress and inform decision making. The system was designed using free and open sources components and seamlessly integrated existing polio surveillance data for real time monitoring of key outbreak response performance indicators. In this article, we describe the design and operation of an electronic dashboard for disease surveillance in an outbreak situation and used the lessons learned to propose key design considerations and functional requirements for online electronic dashboards for disease outbreak response.

Analysis of Decadal Vegetation Dynamics Using Multi-Scale Satellite Images

Science.gov (United States)

Chiang, Y.; Chen, K.

2013-12-01

This study aims at quantifying vegetation fractional cover (VFC) by incorporating multi-resolution satellite images, including Formosat-2(RSI), SPOT(HRV/HRG), Landsat (MSS/TM) and Terra/Aqua(MODIS), to investigate long-term and seasonal vegetation dynamics in Taiwan. We used 40-year NDVI records for derivation of VFC, with field campaigns routinely conducted to calibrate the critical NDVI threshold. Given different sensor capabilities in terms of their spatial and spectral properties, translation and infusion of NDVIs was used to assure NDVI coherence and to determine the fraction of vegetation cover at different spatio-temporal scales. Based on the proposed method, a bimodal sequence of intra-annual VFC which corresponds to the dual-cropping agriculture pattern was observed. Compared to seasonal VFC variation (78~90%), decadal VFC reveals moderate oscillations (81~86%), which were strongly linked with landuse changes and several major disturbances. This time-series mapping of VFC can be used to examine vegetation dynamics and its response associated with short-term and long-term anthropogenic/natural events.

41 CFR 102-118.80 - Who is responsible for keeping my agency's electronic commerce transportation billing records?

Science.gov (United States)

2010-07-01

... keeping my agency's electronic commerce transportation billing records? 102-118.80 Section 102-118.80... Transportation and Transportation Services § 102-118.80 Who is responsible for keeping my agency's electronic commerce transportation billing records? Your agency's internal financial regulations will identify...

Evaluation of vegetation cover using the normalized difference vegetation index (NDVI

Directory of Open Access Journals (Sweden)

Gabriela Camargos Lima

2013-08-01

Full Text Available Soil loss by water erosion is the main cause of soil degradation in Brazil. However, erosion can be reduced by the presence of vegetation. The Normalized Difference Vegetation Index (NDVI makes it possible to identify the vegetative vigor of crops or natural vegetation which facilities the identification of areas with vegetation covers. This information is very important in identifying the phenomena which might be occurring in a particular area, especially those related to soil degradation by water erosion. Thus, the aim of this work was to assess the canopy cover by using NDVI, checking the image accuracy using the Coverage Index (CI based on the Stocking method, in the Sub-basin of Posses, which belongs to the Cantareira System, located in the Extrema municipality, Minas Gerais, Brazil. Landsat-5 TM images were used. The sub-basin of Posses was very altered in comparison to the surrounding areas. The NDVI technique proved to be a suitable tool to assess the uses that occur in the sub-basin of Posses, as validated by the Stocking methodology. The map derived from NDVI allowed the geographic distribution of different land uses to be observed and allowed for the identification of critical areas in relation to vegetation cover as well. This finding can be used to optimize efforts to recover and protect soil in areas with bare soil and degraded pasture, in order to reduce environmental degradation. The CI has not exceeded 40% for land use classes that occur in the majority of the sub-basin (91%, except in areas of woody vegetation.

European Vegetation Archive (EVA)

NARCIS (Netherlands)

Chytrý, Milan; Hennekens, S.M.; Jiménez-Alfaro, Borja; Schaminée, J.H.J.; Haveman, Rense; Janssen, J.A.M.

2016-01-01

The European Vegetation Archive (EVA) is a centralized database of European vegetation plots developed by the IAVS Working Group European Vegetation Survey. It has been in development since 2012 and first made available for use in research projects in 2014. It stores copies of national and

New views on changing Arctic vegetation

Science.gov (United States)

Kennedy, Robert E.

2012-03-01

As climate changes, how will terrestrial vegetation respond? Because the fates of many biogeochemical, hydrological and economic cycles depend on vegetation, this question is fundamental to climate change science but extremely challenging to address. This is particularly true in the Arctic, where temperature change has been most acute globally (IPCC 2007) and where potential feedbacks to carbon, energy and hydrological cycles have important implications for the rest of the Earth system (Chapin et al 2000). It is well known that vegetation is tightly coupled to precipitation and temperature (Whittaker 1975), but predicting the response of vegetation to changes in climate involves much more than invoking the limitations of climate envelopes (Thuiller et al 2008). Models must also consider efficacy of dispersal, soil constraints, ecological interactions, possible CO2 fertilization impacts and the changing impact of other, more proximal anthropogenic effects such as pollution, disturbance, etc (Coops and Waring 2011, Lenihan et al 2008, Scheller and Mladenoff 2005). Given this complexity, a key test will be whether models can match empirical observations of changes that have already occurred. The challenge is finding empirical observations of change that are appropriate to test hypothesized impacts of climate change. As climate gradually changes across broad bioclimatic gradients, vegetation condition may change gradually as well. To capture these gradual trends, observations need at least three characteristics: (1) they must quantify a vegetation attribute that is expected to change, (2) they must measure that attribute in exactly the same way over long periods of time, and (3) they must sample diverse communities at geographic scales commensurate with the scale of expected climatic shifts. Observation networks meeting all three criteria are rare anywhere on the globe, but particularly so in remote areas. For this reason, satellite images have long been used as a

Vegetation and invertebrate community response to eastern hemlock decline in southern new England

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Laura L. Ingwell; Mailea Miller-Pierce; R. Talbot Trotter; Evan L. Preisser

2012-01-01

The introduction of Adelges tsugae (Hemlock Woolly Adelgid [HWA]) to the eastern United States has had a devastating impact on Tsuga canadensis (Eastern Hemlock). Although much research has been done to assess HWA impacts on ecosystem processes and vegetation structure, few researchers have examined community-level changes in...

Rapid responses of permafrost and vegetation to experimentally increased snow cover in sub-arctic Sweden

International Nuclear Information System (INIS)

Johansson, Margareta; Bosiö, Julia; Akerman, H Jonas; Jackowicz-Korczynski, Marcin; Christensen, Torben R; Callaghan, Terry V

2013-01-01

Increased snow depth already observed, and that predicted for the future are of critical importance to many geophysical and biological processes as well as human activities. The future characteristics of sub-arctic landscapes where permafrost is particularly vulnerable will depend on complex interactions between snow cover, vegetation and permafrost. An experimental manipulation was, therefore, set up on a lowland peat plateau with permafrost, in northernmost Sweden, to simulate projected future increases in winter precipitation and to study their effects on permafrost and vegetation. After seven years of treatment, statistically significant differences between manipulated and control plots were found in mean winter ground temperatures, which were 1.5 ° C higher in manipulated plots. During the winter, a difference in minimum temperatures of up to 9 ° C higher could be found in individual manipulated plots compared with control plots. Active layer thicknesses increased at the manipulated plots by almost 20% compared with the control plots and a mean surface subsidence of 24 cm was recorded in the manipulated plots compared to 5 cm in the control plots. The graminoid Eriophorum vaginatum has expanded in the manipulated plots and the vegetation remained green longer in the season. (letter)

Engineers' Responsibilities for Global Electronic Waste: Exploring Engineering Student Writing Through a Care Ethics Lens.

Science.gov (United States)

Campbell, Ryan C; Wilson, Denise

2017-04-01

This paper provides an empirically informed perspective on the notion of responsibility using an ethical framework that has received little attention in the engineering-related literature to date: ethics of care. In this work, we ground conceptual explorations of engineering responsibility in empirical findings from engineering student's writing on the human health and environmental impacts of "backyard" electronic waste recycling/disposal. Our findings, from a purposefully diverse sample of engineering students in an introductory electrical engineering course, indicate that most of these engineers of tomorrow associated engineers with responsibility for the electronic waste (e-waste) problem in some way. However, a number of responses suggested attempts to deflect responsibility away from engineers towards, for example, the government or the companies for whom engineers work. Still other students associated both engineers and non-engineers with responsibility, demonstrating the distributed/collective nature of responsibility that will be required to achieve a solution to the global problem of excessive e-waste. Building upon one element of a framework for care ethics adopted from the wider literature, these empirical findings are used to facilitate a preliminary, conceptual exploration of care-ethical responsibility within the context of engineering and e-waste recycling/disposal. The objective of this exploration is to provide a first step toward understanding how care-ethical responsibility applies to engineering. We also hope to seed dialogue within the engineering community about its ethical responsibilities on the issue. We conclude the paper with a discussion of its implications for engineering education and engineering ethics that suggests changes for educational policy and the practice of engineering.

Landfill cover soil, soil solution, and vegetation responses to municipal landfill leachate applications.

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Macdonald, Neil W; Rediske, Richard R; Scull, Brian T; Wierzbicki, David

2008-01-01

Municipal solid waste landfill leachate must be removed and treated to maintain landfill cover integrity and to prevent contamination of surface and ground waters. From 2003 to 2007, we studied an onsite disposal system in Ottawa County, Michigan, where leachate was spray irrigated on the vegetated landfill cover. We established six 20-m-diameter circular experimental plots on the landfill; three were spray irrigated as part of the operational system, and three remained as untreated control plots. We quantified the effects of leachate application on soil properties, soil solution chemistry, vegetative growth, and estimated solute leaching. The leachate had high mean levels of electrical conductivity (0.6-0.7 S m(-1)), Cl (760-900 mg L(-1)), and NH(4)-N (290-390 mg L(-1)) but was low in metals and volatile organic compounds. High rates of leachate application in 2003 (32 cm) increased soil electrical conductivity and NO(3)-N leaching, so a sequential rotation of spray areas was implemented to limit total leachate application to <9.6 cm yr(-1) per spray area. Concentrations of NO(3)-N and leaching losses remained higher on irrigated plots in subsequent years but were substantially reduced by spray area rotation. Leachate irrigation increased plant biomass but did not significantly affect soil metal concentrations, and plant metal concentrations remained within normal ranges. Rotating spray areas and timing irrigation to conform to seasonal capacities for evapotranspiration reduced the localized impacts of leachate application observed in 2003. Careful monitoring of undiluted leachate applications is required to avoid adverse impacts to vegetation or soils and elevated solute leaching losses.

Children and vegetables: strategies to increase children’s liking and intake of vegetables

NARCIS (Netherlands)

Wild, de V.W.T.

2015-01-01

Background and aim

Children’s vegetable intake is far below that recommended. Despite increased awareness of the importance of vegetable consumption for health, it remains challenging to improve children’s vegetable intake. Since food preferences are central to

Radiation preservation and test marketing of fruits and vegetables

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Zhicheng, Xu; Dong, Cai; Fuying, He; Deyao, Zhao

1993-07-01

To develop the technology for radiation preservation of fruits and vegetables, many varieties of fruits and vegetables had been researched. Results showed that the low dose irradiation is useful to preservation of fruits and vegetables. On the besis of research, 1900 tons garlic, 950 tons onion, 500 tons potatoes, 710 tons apples and 1000 kg litchi had been irradiated in commercial scale. The quality control standards of irradiated garlic, onion and potato had been established and used for commercial scale irradiation. In order to collect consumers in store response to irradiated foods, a special counter was set up for selling irradiated apples in Nan Jing Road (W), Shanghai. 634 sheets of consumer in-store respense investigation forms have been returned and analysed. These results showed that when consumer understands the benefit of irradiation preservation such as higher quality, greater safety, longer shelf-live, wide product availability, or good prices for value, consumer would willingly buy irradiated food.

Relations between Vegetation and Geologic Framework in Barrier Island

Science.gov (United States)

Smart, N. H.; Ferguson, J. B.; Lehner, J. D.; Taylor, D.; Tuttle, L. F., II; Wernette, P. A.

2017-12-01

Barrier islands provide valuable ecosystems and protective services to coastal communities. The longevity of barrier islands is threatened by sea-level rise, human impacts, and extreme storms. The purpose of this research is to evaluate how vegetation dynamics interact with the subsurface and offshore framework geology to influence the beach and dune morphology. Beach and dune morphology can be viewed as free and/or forced behavior, where free systems are stochastic and the morphology is dependent on variations in the storm surge run-up, aeolian sediment supply and transport potential, and vegetation dynamics and persistence. Forced systems are those where patterns in the coastal morphology are determined by some other structural control, such as the underlying and offshore framework geology. Previous studies have documented the effects of geologic framework or vegetation dynamics on the beach and dunes, although none have examined possible control by vegetation dynamics in context of the geologic framework (i.e. combined free and forced behavior). Padre Island National Seashore (PAIS) was used to examine the interaction of free and forced morphology because the subsurface framework geology and surface beach and dune morphology are variable along the island. Vegetation dynamics were assessed by classifying geographically referenced historical aerial imagery into areas with vegetation and areas without vegetation, as well as LiDAR data to verify this imagery. The subsurface geologic structure was assessed using a combination of geophysical surveys (i.e. electromagnetic induction, ground-penetrating radar, and offshore seismic surveys). Comparison of the observed vegetation patterns and geologic framework leads to a series of questions surrounding how mechanistically these two drivers of coastal morphology are related. Upcoming coring and geophysical surveys will enable us to validate new and existing geophysical data. Results of this paper will help us better

Insights into the pathogenesis and clinicopathological spectrum of oral vegetable granuloma. Case series with literature review

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Shankargouda Patil

2017-10-01

Full Text Available Oral vegetable granuloma represents an inflammatory lesion of foreign body origin resulting from the implantation of vegetable matter. Controversy regarding its pathogenesis is reflected by the various terminologies used to describe the lesion. Its diverse clinical presentations are due to variations in the antigenic potential of the vegetable material and the host response. As the diagnosis is solely histopathological, it is critical to differentiate vegetable granuloma from other oral granulomatous lesions like tuberculosis, sarcoidosis and Wegner’s granulomatosis. Here, we report six cases with the varied clinicopathological presentation of hyaline ring granulomas in association with different pathological lesions.

Formation of banded vegetation patterns resulted from interactions between sediment deposition and vegetation growth.

Science.gov (United States)

Huang, Tousheng; Zhang, Huayong; Dai, Liming; Cong, Xuebing; Ma, Shengnan

2018-03-01

This research investigates the formation of banded vegetation patterns on hillslopes affected by interactions between sediment deposition and vegetation growth. The following two perspectives in the formation of these patterns are taken into consideration: (a) increased sediment deposition from plant interception, and (b) reduced plant biomass caused by sediment accumulation. A spatial model is proposed to describe how the interactions between sediment deposition and vegetation growth promote self-organization of banded vegetation patterns. Based on theoretical and numerical analyses of the proposed spatial model, vegetation bands can result from a Turing instability mechanism. The banded vegetation patterns obtained in this research resemble patterns reported in the literature. Moreover, measured by sediment dynamics, the variation of hillslope landform can be described. The model predicts how treads on hillslopes evolve with the banded patterns. Thus, we provide a quantitative interpretation for coevolution of vegetation patterns and landforms under effects of sediment redistribution. Copyright © 2018. Published by Elsevier Masson SAS.

Prediction of fruit and vegetable intake from biomarkers using individual participant data of diet-controlled intervention studies

NARCIS (Netherlands)

Souverein, O.W.; Vries, J.H.M. de; Freese, R.; Watzl, B.; Bub, A.; Miller, E.R., III; Castenmiller, J.J.M.; Pasman, W.J.; Hof, K. van het; Chopra, M.; Karlsen, A.; Dragsted, L.O.; Winkels, R.; Itsiopoulos, C.; Brazionis, L.; O'Dea, K.; Loo-Bouwman, C.A. van; Naber, T.H.J.; Voet, H. van der; Boshuizen, H.C.

2015-01-01

Fruit and vegetable consumption produces changes in several biomarkers in blood. The present study aimed to examine the dose-response curve between fruit and vegetable consumption and carotenoid (α-carotene, β-carotene, β-cryptoxanthin, lycopene, lutein and zeaxanthin), folate and vitamin C

The impact of geoengineering on vegetation in experiment G1 of the GeoMIP

Science.gov (United States)

Glienke, Susanne; Irvine, Peter J.; Lawrence, Mark G.

2015-10-01

Solar Radiation Management (SRM) has been proposed as a mean to partly counteract global warming. The Geoengineering Model Intercomparison Project (GeoMIP) has simulated the climate consequences of a number of SRM techniques. Thus far, the effects on vegetation have not yet been thoroughly analyzed. Here the vegetation response to the idealized GeoMIP G1 experiment from eight fully coupled Earth system models (ESMs) is analyzed, in which a reduction of the solar constant counterbalances the radiative effects of quadrupled atmospheric CO2 concentrations (abrupt4 × CO2). For most models and regions, changes in net primary productivity (NPP) are dominated by the increase in CO2, via the CO2 fertilization effect. As SRM will reduce temperatures relative to abrupt4 × CO2, in high latitudes this will offset increases in NPP. In low latitudes, this cooling relative to the abrupt4 × CO2 simulation decreases plant respiration while having little effect on gross primary productivity, thus increasing NPP. In Central America and the Mediterranean, generally dry regions which are expected to experience increased water stress with global warming, NPP is highest in the G1 experiment for all models due to the easing of water limitations from increased water use efficiency at high-CO2 concentrations and the reduced evaporative demand in a geoengineered climate. The largest differences in the vegetation response are between models with and without a nitrogen cycle, with a much smaller CO2 fertilization effect for the former. These results suggest that until key vegetation processes are integrated into ESM predictions, the vegetation response to SRM will remain highly uncertain.

Anti-inflammatory effects of phytochemicals from fruits, vegetables, and food legumes: A review.

Science.gov (United States)

Zhu, Fengmei; Du, Bin; Xu, Baojun

2018-05-24

Inflammation is the first biological response of the immune system to infection, injury or irritation. Evidence suggests that the anti-inflammatory effect is mediated through the regulation of various inflammatory cytokines, such as nitric oxide, interleukins, tumor necrosis factor alpha-α, interferon gamma-γ as well as noncytokine mediator, prostaglandin E 2 . Fruits, vegetables, and food legumes contain high levels of phytochemicals that show anti-inflammatory effect, but their mechanisms of actions have not been completely identified. The aim of this paper was to summarize the recent investigations and findings regarding in vitro and animal model studies on the anti-inflammatory effects of fruits, vegetables, and food legumes. Specific cytokines released for specific type of physiological event might shed some light on the specific use of each source of phytochemicals that can benefit to counter the inflammatory response. As natural modulators of proinflammatory gene expressions, phytochemical from fruits, vegetables, and food legumes could be incorporated into novel bioactive anti-inflammatory formulations of various nutraceuticals and pharmaceuticals. Finally, these phytochemicals are discussed as the natural promotion strategy for the improvement of human health status. The phenolics and triterpenoids in fruits and vegetables showed higher anti-inflammatory activity than other compounds. In food legumes, lectins and peptides had anti-inflammatory activity in most cases. However, there are lack of human study data on the anti-inflammatory activity of phytochemicals from fruits, vegetables, and food legumes.

Irradiation of dehydrated vegetables

International Nuclear Information System (INIS)

Esterhuyse, A; Esterhuizen, T.

1985-01-01

The reason for radurization was to decreased the microbial count of dehydrated vegetables. The average absorbed irradiation dose range between 2kGy and 15kGy. The product catagories include a) Green vegetables b) White vegetables c) Powders of a) and b). The microbiological aspects were: Declining curves for the different products of T.P.C., Coliforms, E. Coli, Stap. areus, Yeast + Mold at different doses. The organoleptical aspects were: change in taste, flavour, texture, colour and moisture. The aim is the marketing of irradiated dehydrated vegetables national and international basis

Recent slowdown of atmospheric CO2 amplification due to vegetation-climate feedback over northern lands

Science.gov (United States)

Li, Z.; Xia, J.; Ahlström, A.; Rinke, A.; Koven, C.; Hayes, D. J.; Ji, D.; Zhang, G.; Krinner, G.; Chen, G.; Dong, J.; Liang, J.; Moore, J.; Jiang, L.; Yan, L.; Ciais, P.; Peng, S.; Wang, Y.; Xiao, X.; Shi, Z.; McGuire, A. D.; Luo, Y.

2017-12-01

The enhanced vegetation growth by climate warming plays a pivotal role in amplifying the seasonal cycle of atmospheric CO2 at northern high latitudes since 1960s1-3. It remains unclear that whether this mechanism is still robust since 1990s, because a paused vegetation growth increase4,5 and weakened temperature control on CO2 uptake6,7 have been detected during this period. Here, based on in-situ atmospheric CO2 concentration records above northern 50o N, we found a slowdown of the atmospheric CO2 amplification from the mid-1990s to mid-2000s. This phenomenon is associated with the pause of vegetation greening trend and slowdown of spring warming. We further showed that both the vegetation greenness and its growing season length are positively correlated to spring but not autumn temperature from 1982 to 2010 over the northern lands. However, the state-of-art terrestrial biosphere models produce positive responses of gross primary productivity to both spring and autumn warming. These findings emphasize the importance of vegetation-climate feedback in shaping the atmospheric CO2 seasonality, and call for an improved carbon-cycle response to non-uniform seasonal warming at high latitudes in current models.

Remote sensing of Sonoran Desert vegetation structure and phenology with ground-based LiDAR

Science.gov (United States)

Sankey, Joel B.; Munson, Seth M.; Webb, Robert H.; Wallace, Cynthia S.A.; Duran, Cesar M.

2015-01-01

Long-term vegetation monitoring efforts have become increasingly important for understanding ecosystem response to global change. Many traditional methods for monitoring can be infrequent and limited in scope. Ground-based LiDAR is one remote sensing method that offers a clear advancement to monitor vegetation dynamics at high spatial and temporal resolution. We determined the effectiveness of LiDAR to detect intra-annual variability in vegetation structure at a long-term Sonoran Desert monitoring plot dominated by cacti, deciduous and evergreen shrubs. Monthly repeat LiDAR scans of perennial plant canopies over the course of one year had high precision. LiDAR measurements of canopy height and area were accurate with respect to total station survey measurements of individual plants. We found an increase in the number of LiDAR vegetation returns following the wet North American Monsoon season. This intra-annual variability in vegetation structure detected by LiDAR was attributable to a drought deciduous shrub Ambrosia deltoidea, whereas the evergreen shrub Larrea tridentata and cactus Opuntia engelmannii had low variability. Benefits of using LiDAR over traditional methods to census desert plants are more rapid, consistent, and cost-effective data acquisition in a high-resolution, 3-dimensional context. We conclude that repeat LiDAR measurements can be an effective method for documenting ecosystem response to desert climatology and drought over short time intervals and at detailed-local spatial scale.

Influence of a vegetable fat blend on the texture, microstructure and sensory properties of kashar cheese

Energy Technology Data Exchange (ETDEWEB)

Dinkci, N.; Kesenkas, H.; Seckin, A. K.; Kinik, O.; Gonc, S.

2011-07-01

The possibility of using a commercial vegetable fat blend in Kashar cheese was investigated. Kashar cheeses were manufactured by replacing the milk fat (MF) with a vegetable fat (VF) blend. Kashar cheeses from whole milk were also manufactured to compare textural, microstructural, meltability, color and sensory characteristics during a ripening period of 90 days. The use of vegetable fat decreased the meltability, hardness, cohesiveness, gumminess and chewiness of the cheese; while increasing adhesiveness where springiness was not affected. Differences became less notable toward the end of ripening. Scanning electron micrographs displayed VF cheese with a compact network with small and uniform fat globules embedded in the protein matrix. The MF cheese exhibited an open protein matrix containing milk fat globules of various sizes and forms. The color analysis demonstrated significant differences between cheeses. Finally, all sensory characteristics of the cheese were affected by the vegetable fat blend. (Author) 36 refs.

Permafrost warming and vegetation changes in continental Antarctica

International Nuclear Information System (INIS)

Guglielmin, Mauro; Dalle Fratte, Michele; Cannone, Nicoletta

2014-01-01

Continental Antarctica represents the last pristine environment on Earth and is one of the most suitable contexts to analyze the relations between climate, active layer and vegetation. In 2000 we started long-term monitoring of the climate, permafrost, active layer and vegetation in Victoria Land, continental Antarctica. Our data confirm the stability of mean annual and summer air temperature, of snow cover, and an increasing trend of summer incoming short wave radiation. The active layer thickness is increasing at a rate of 0.3 cm y −1 . The active layer is characterized by large annual and spatial differences. The latter are due to scarce vegetation, a patchy and very thin organic layer and large spatial differences in snow accumulation. The active layer thickening, probably due to the increase of incoming short wave radiation, produced a general decrease of the ground water content due to the better drainage of the ground. The resultant drying may be responsible for the decline of mosses in xeric sites, while it provided better conditions for mosses in hydric sites, following the species-specific water requirements. An increase of lichen vegetation was observed where the climate drying occurred. This evidence emphasizes that the Antarctic continent is experiencing changes that are in total contrast to the changes reported from maritime Antarctica. (paper)

Early neuro-vegetative responses to head irradiation of the rabbit at mean absorbed doses of 1000 and 150 rads

International Nuclear Information System (INIS)

Dufour, Raymond.

1977-10-01

Head irradiation was studied in order to back up a previous assumption on the kinetics of vegetative responses to whole-body exposure: the earliest response might have a central origin and explain the slight increase of blood pressure, tachycardia, hyperthermia and hyperventilation. Following head exposure at a mean absorbed dose of 1000 rads, blood pressure increased on the 15 th min, reaching 0.8 - 1 cm Hg on the 30th min and during 7 - 8 hours. The increase of heart rate occured as early and was about 40% and lasted for 24 hours. Body temperature increased as early as the end of exposure, was highest within 2 - 2.30 hours and decreased on the 6th hour. Arterial blood showed a respiratory alkalosis on the 1st hour, lasting after the 6th hour and disappeared within 24 hours. At a dose of 150 rads, the changes were lasting but of lower importance and duration. The results show that early changes following whole-body exposure also occur after head exposure and are magnified. The kinetics involved are discussed [fr

Vegetable Genetic Resources in China

Directory of Open Access Journals (Sweden)

Haiping WANG

2018-03-01

Full Text Available China is recognized as an important region for plant biodiversity based on its vast and historical collection of vegetable germplasm. The aim of this review is to describe the exploration status of vegetable genetic resources in China, including their collection, preservation, evaluation, and utilization. China has established a number of national-level vegetable genetic resources preservation units, including the National Mid-term Genebank for Vegetable Germplasm Resources, the National Germplasm Repository for Vegetatively-Propagated Vegetables, and the National Germplasm Repository for Aquatic Vegetables. In 2015, at least 36 000 accessions were collected and preserved in these units. In the past decade, 44 descriptors and data standards for different species have been published, and most accessions have been evaluated for screening the germplasms for specific important traits such as morphological characteristics, disease resistance, pest resistance, and stress tolerance. Moreover, the genetic diversity and evolution of some vegetable germplasms have been evaluated at the molecular level. Recently, more than 1 000 accessions were distributed to researchers and breeders each year by various means for vegetable research and production. However, additional wild-relative and abroad germplasms from other regions need to be collected and preserved in the units to expand genetic diversity. Furthermore, there is a need to utilize advanced techniques to better understand the background and genetic diversity of a wide range of vegetable genetic resources. This review will provide agricultural scientists’ insights into the genetic diversity in China and provide information on the distribution and potential utilization of these valuable genetic resources. Keywords: vegetable, genetic resource, preservation, evaluation, utilization

Fruits, vegetables and lung cancer risk: a systematic review and meta-analysis.

Science.gov (United States)

Vieira, A R; Abar, L; Vingeliene, S; Chan, D S M; Aune, D; Navarro-Rosenblatt, D; Stevens, C; Greenwood, D; Norat, T

2016-01-01

Lung cancer is the most common cause of cancer death. Fruits and vegetables containing carotenoids and other antioxidants have been hypothesized to decrease lung cancer risk. As part of the World Cancer Research Fund International Continuous Update Project, we conducted a systematic review and meta-analysis of prospective studies. We searched PubMed and several databases up to December 2014 for prospective studies. We conducted meta-analyses comparing the highest and lowest intakes and dose-response meta-analyses to estimate summary relative risks (RRs) and 95% confidence intervals (CIs), and examine possible non-linear associations. We combined results from the Pooling Project with the studies we identified to increase the statistical power of our analysis. When comparing the highest with the lowest intakes, the summary RR estimates were 0.86 [95% CI 0.78-0.94; n (studies) = 18] for fruits and vegetables, 0.92 (95% CI 0.87-0.97; n = 25) for vegetables and 0.82 (95% CI 0.76-0.89; n = 29) for fruits. The association with fruit and vegetable intake was marginally significant in current smokers and inverse but not significant in former or never smokers. Significant inverse dose-response associations were observed for each 100 g/day increase: for fruits and vegetables [RR: 0.96; 95% CI 0.94-0.98, I(2) = 64%, n = 14, N (cases) = 9609], vegetables (RR: 0.94; 95% CI 0.89-0.98, I(2) = 48%, n = 20, N = 12 563) and fruits (RR: 0.92; 95% CI 0.89-0.95, I(2) = 57%, n = 23, N = 14 506). Our results were consistent among the different types of fruits and vegetables. The strength of the association differed across locations. There was evidence of a non-linear relationship (P fruit and vegetable intake and lung cancer risk showing that no further benefit is obtained when increasing consumption above ∼400 g per day. Eliminating tobacco smoking is the best strategy to prevent lung cancer. Although residual confounding by smoking cannot be ruled out, the current evidence from

Electron irradiation response on Ge and Al-doped SiO{sub 2} optical fibres

Energy Technology Data Exchange (ETDEWEB)

Yaakob, N.H.; Wagiran, H. [Department of Physics, Universiti Teknologi Malaysia, 81310 Skudai, Johor Darul Takzim (Malaysia); Hossain, I., E-mail: imamhossain@utm.m [Department of Physics, Universiti Teknologi Malaysia, 81310 Skudai, Johor Darul Takzim (Malaysia); Ramli, A.T. [Department of Physics, Universiti Teknologi Malaysia, 81310 Skudai, Johor Darul Takzim (Malaysia); Bradley, D.A [Department of Physics, University of Surrey, Guildford GU2 7XH (United Kingdom); Hashim, S. [Department of Physics, Universiti Teknologi Malaysia, 81310 Skudai, Johor Darul Takzim (Malaysia); Ali, H. [Department of Radiotherapy and Oncology, Hospital Sultan Ismail, Johor Darul Takzim (Malaysia)

2011-05-01

This paper describes the thermoluminescence response, sensitivity, stability and reproducibility of SiO{sub 2} optical fibres with various electron energies and doses. The TL materials that comprise Al- and Ge-doped silica fibres were used in this experiment. The TL results are compared with those of the commercially available TLD-100. The doped SiO{sub 2} optical fibres and TLD-100 are placed in a solid phantom and irradiated with 6, 9 and 12 MeV electron beams at doses ranging from 0.2 to 4.0 Gy using the LINAC at Hospital Sultan Ismail, Johor Bahru, Malaysia. It was found that the commercially available Al- and Ge-doped optical fibres have a linear dose-TL signal relationship. The intensity of TL response of Ge-doped fibre is markedly greater than that of the Al-doped fibre.

Change in Vegetation Growth and Its Feedback to Climate in the Tibet Plateau

Science.gov (United States)

Piao, S.

2015-12-01

Vegetation growth is strongly influenced by climate and climate change and can affect the climate system through a number of bio-physical processes. As a result, monitoring, understanding and predicting the response of vegetation growth to global change has been a central activity in Earth system science during the past two decades. The Tibetan Plateau (TP) has experienced a pronounced warming over recent decades. The warming rate of the TP over the period 1960-2009 was about twice the global average warming rate, yet with heterogeneous patterns. In this study, we use satellite derived NDVI data to investigate spatio-temporal change in vegetation growth over the last three decades.

The response of vegetation to rising CO2 concentrations plays an important role in future changes in the hydrological cycle

Science.gov (United States)

Hong, Tao; Dong, Wenjie; Ji, Dong; Dai, Tanlong; Yang, Shili; Wei, Ting

2018-04-01

The effects of increasing CO2 concentrations on plant and carbon cycle have been extensively investigated; however, the effects of changes in plants on the hydrological cycle are still not fully understood. Increases in CO2 modify the stomatal conductance and water use of plants, which may have a considerable effect on the hydrological cycle. Using the carbon-climate feedback experiments from CMIP5, we estimated the responses of plants and hydrological cycle to rising CO2 concentrations to double of pre-industrial levels without climate change forcing. The mode results show that rising CO2 concentrations had a significant influence on the hydrological cycle by changing the evaporation and transpiration of plants and soils. The increases in the area covered by plant leaves result in the increases in vegetation evaporation. Besides, the physiological effects of stomatal closure were stronger than the opposite effects of changes in plant structure caused by the increases in LAI (leaf area index), which results in the decrease of transpiration. These two processes lead to overall decreases in evaporation, and then contribute to increases in soil moisture and total runoff. In the dry areas, the stronger increase in LAI caused the stronger increases in vegetation evaporation and then lead to the overall decreases in P - E (precipitation minus evaporation) and soil moisture. However, the soil moisture in sub-arid and wet areas would increase, and this may lead to the soil moisture deficit worse in the future in the dry areas. This study highlights the need to consider the different responses of plants and the hydrological cycle to rising CO2 in dry and wet areas in future water resources management, especially in water-limited areas.

Correlates of fruit and vegetable consumption among construction laborers and motor freight workers.

Science.gov (United States)

Nagler, Eve M; Viswanath, K; Ebbeling, Cara B; Stoddard, Anne M; Sorensen, Glorian

2013-04-01

The aim of this study was to compare and contrast correlates of fruit and vegetable consumption in two blue-collar populations: construction laborers and motor freight workers. Cross-sectional data were collected from two groups of male workers: (1) construction laborers (n = 1,013; response rate = 44 %) randomly selected from a national sample, as part of a diet and smoking cessation study; and (2) motor freight workers (n = 542; response rate = 78 %) employed in eight trucking terminals, as part of a tobacco cessation and weight management study. Data were analyzed using linear regression modeling methods. For both groups, higher income and believing it was important to eat right because of work were positively associated with fruit and vegetable consumption; conversely, being white was associated with lower intake. Construction laborers who reported eating junk food due to workplace stress and fatigue had lower fruit and vegetable intake. For motor freight workers, perceiving fast food to be the only choice at work and lack of time to eat right were associated with lower consumption. Comparing occupational groups illustrates how work experiences may be related to fruit and vegetable consumption in different ways as well as facilitates the development of interventions that can be used across groups.

Histochemical and polarization microscopic study of two cases of vegetable/pulse granuloma

Directory of Open Access Journals (Sweden)

Manjunatha B

2008-01-01

Full Text Available Vegetable granuloma (VG or pulse granuloma (PG results from the implantation of food particles of plant or vegetable origin. It is usually seen in the periapical or in the sulcus areas. These lesions have been described as a distinct entity and classified into central and peripheral lesions according to the location. Central lesions are asymptomatic, whereas peripheral lesions present as painless sub-mucosal swellings. Many authors have postulated that food particles in VG or PG get implanted and are rapidly digested, and sometimes partly get altered by host responses. The cellulose part of plant foods being indigestible persists in the form of hyaline material, whereas the starch matter gets digested. This cellulose moiety invokes chronic granulomatous response.

Comparing light sensitivity, linearity and step response of electronic cameras for ophthalmology.

Science.gov (United States)

Kopp, O; Markert, S; Tornow, R P

2002-01-01

To develop and test a procedure to measure and compare light sensitivity, linearity and step response of electronic cameras. The pixel value (PV) of digitized images as a function of light intensity (I) was measured. The sensitivity was calculated from the slope of the P(I) function, the linearity was estimated from the correlation coefficient of this function. To measure the step response, a short sequence of images was acquired. During acquisition, a light source was switched on and off using a fast shutter. The resulting PV was calculated for each video field of the sequence. A CCD camera optimized for the near-infrared (IR) spectrum showed the highest sensitivity for both, visible and IR light. There are little differences in linearity. The step response depends on the procedure of integration and read out.

Heavy metals in green vegetables and soils from vegetable gardens ...

African Journals Online (AJOL)

Edible portions of five varieties of green vegetables, namely amaranth, chinese cabbage, cowpea leaves, leafy cabbage and pumpkin leaves, collected from several areas in Dar es Salaam, were analyzed for lead, cadmium, chromium, zinc, nickel and copper. Except for zinc, the levels of heavy metals in the vegetables ...

Engineers’ Responsibilities for Global Electronic Waste: Exploring Engineering Student Writing Through a Care Ethics Lens

Science.gov (United States)

Campbell, Ryan C.; Wilson, Denise

2016-01-01

This paper provides an empirically informed perspective on the notion of responsibility using an ethical framework that has received little attention in the engineering-related literature to date: ethics of care. In this work, we ground conceptual explorations of engineering responsibility in empirical findings from engineering student’s writing on the human health and environmental impacts of “backyard” electronic waste recycling/disposal. Our findings, from a purposefully diverse sample of engineering students in an introductory electrical engineering course, indicate that most of these engineers of tomorrow associated engineers with responsibility for the electronic waste (e-waste) problem in some way. However, a number of responses suggested attempts to deflect responsibility away from engineers towards, for example, the government or the companies for whom engineers work. Still other students associated both engineers and non-engineers with responsibility, demonstrating the distributed/collective nature of responsibility that will be required to achieve a solution to the global problem of excessive e-waste. Building upon one element of a framework for care ethics adopted from the wider literature, these empirical findings are used to facilitate a preliminary, conceptual exploration of care-ethical responsibility within the context of engineering and e-waste recycling/disposal. The objective of this exploration is to provide a first step toward understanding how care-ethical responsibility applies to engineering. We also hope to seed dialogue within the engineering community about its ethical responsibilities on the issue. We conclude the paper with a discussion of its implications for engineering education and engineering ethics that suggests changes for educational policy and the practice of engineering. PMID:27368195

Potential applications of ionizing radiation in postharvest handling of fresh fruits and vegetables

International Nuclear Information System (INIS)

Kader, A.A.

1986-01-01

The advantages and limitations of potential uses of ionizing radiation of harvested fresh fruits and vegetables are discussed. Potential applications include: sprout inhibition of tuber, bulb, and root vegetables; inhibition of post-harvest growth of asparagus and mushrooms; insect disinfestation; alteration of ripening and senescence in fresh fruits; and post-harvest microorganism disease control. Cost, consumer acceptance, and logistical problems are cited as possible limiting factors. Factors influencing response also are discussed

Optimum Vegetation Conditions for Successful Establishment of Planted Eastern White Pine (Pinus strobus L.

Directory of Open Access Journals (Sweden)

Douglas G. Pitt

2016-08-01

Full Text Available The 10th-growing season performance of planted eastern white pine (Pinus strobus L. seedlings was evaluated in response to herbaceous and woody vegetation control treatments within a clearcut and two variants of the uniform shelterwood regeneration system (single vs. multiple future removal cuts. Herbaceous vegetation control involved the suppression of grasses, forbs, ferns and low shrubs for the first 2 or 4 growing seasons after planting. Deciduous woody vegetation control treatments, conducted in combination with the herbaceous treatments within a response-surface design, involved the permanent removal of all tall shrubs and deciduous trees at the time of planting, at the end of the 2nd or 5th growing seasons, or not at all. In general, the average size of planted pine was related positively to the duration of herbaceous vegetation control and negatively to delays in woody control. White pine weevil (Pissodes strobi Peck altered these trends, reducing the height of pine on plots with little or no overtopping deciduous woody vegetation or mature tree cover. Where natural pine regeneration occurred on these plots, growth was similar but subordinate to the planted pine. Data from the three sites indicate that at least 60% of planted pine may be expected to reach an age-10 height target of 2.5 m when overtopping cover (residual overstory + regenerating deciduous is managed at approximately 65% ± 10%, and total herbaceous cover is suppressed to levels not exceeding 50% in the first five years. On productive sites, this combination may be difficult to achieve in a clearcut, and requires fairly rigorous vegetation management in shelterwood regeneration systems. Currently, synthetic herbicides offer the only affordable and effective means of achieving such vegetation control.

Effects of climate change on forest vegetation in the Northern Rockies Region [Chapter 6

Science.gov (United States)

Keane, Robert E.; Mahalovich, Mary Frances; Bollenbacher, Barry L.; Manning, Mary E.; Loehman, Rachel A.; Jain, Terrie B.; Holsinger, Lisa M.; Larson, Andrew J.; Webster, Meredith M.

2018-01-01

The projected rapid changes in climate will affect the unique vegetation assemblages of the Northern Rockies region in myriad ways, both directly through shifts in vegetation growth, mortality, and regeneration, and indirectly through changes in disturbance regimes and interactions with changes in other ecosystem processes, such as hydrology, snow dynamics, and exotic invasions (Bonan 2008; Hansen and Phillips 2015; Hansen et al. 2001; Notaro et al. 2007). These impacts, taken collectively, could change the way vegetation is managed by public land agencies in this area. Some species may be in danger of rapid decreases in abundance, while others may undergo range expansion (Landhäusser et al. 2010). New vegetation communities may form, while historical vegetation complexes may simply shift to other areas of the landscape or become rare. Juxtaposed with climate change concerns are the consequences of other land management policies and past activities, such as fire exclusion, fuels treatments, and grazing. A thorough assessment of the responses of vegetation to projected climate change is needed, along with an evaluation of the vulnerability of important species, communities, and vegetation-related resources that may be influenced by the effects, both direct and indirect, of climate change. This assessment must also account for past management actions and current vegetation conditions and their interactions with future climates.

Skin and plasma carotenoid response to a provided intervention diet high in vegetables and fruit: uptake and depletion kinetics

Science.gov (United States)

Background: Objective biomarkers are needed to assess adherence to vegetable and fruit intervention trials. Blood carotenoids are considered the best biomarker of vegetable and fruit intake but collecting blood is invasive and the analyses are relatively expensive for population studies. Resonance ...

Consumption of raw vegetables and fruits: a risk factor for Campylobacter infections.

Science.gov (United States)

Verhoeff-Bakkenes, L; Jansen, H A P M; in 't Veld, P H; Beumer, R R; Zwietering, M H; van Leusden, F M

2011-01-05

The purpose of this study was to determine the prevalence of Campylobacter in fresh vegetables and fruits at retail level in the Netherlands, and to estimate its implications on the importance of vegetables and fruits as risk factor for campylobacteriosis. Thirteen of the 5640 vegetable and fruit samples were Campylobacter positive, resulting in a prevalence of 0.23% (95% confidence interval (Cl): 0.12-0.39%). The prevalence of packaged products (0.36%, 95% Cl: 0.17-0.66) was significantly higher than of unpackaged products (0.07; 95% Cl: 0.01-0.27). No statistical differences were found between seasons. Combining the mean prevalence found in this study with data on the consumption of vegetables and fruits, an exposure of 0.0048 campylobacters ingested per person per day in the Netherlands by transmission via vegetables and fruits, was calculated. This exposure, as input in a Beta-Poisson dose-response model, resulted in an estimated number of 5.3×10⁵ cases of infection with Campylobacter per year for the whole Dutch population. This constitutes the consumption of raw vegetables and fruits, especially when packaged, to be a risk factor for Campylobacter infections. Copyright © 2010 Elsevier B.V. All rights reserved.

Functionalized Vegetable Oils for Utilization as Polymer Building Blocks: Office of Industrial Technologies (OIT) Agriculture Project Fact Sheet

International Nuclear Information System (INIS)

Carde, T.

2001-01-01

Vegetable oils such as soybean oil will be converted to novel polymers using hydroformylation and other catalytic processes. These polymers can be used in the construction, automotive, packaging, and electronic sectors

The Response of CMS Combined Calorimeters to Single Hadrons, Electrons and Muons

CERN Document Server

Akchurin, Nural; Gumus, Kazim; Jeong Chi Young; Kim Hee Jong; Lee Sung Won; Roh, Youn; Volobouev, Igor; Wigmans, Richard

2007-01-01

We report on the response of the combined CMS electromagnetic (EB) and hadronic barrel (HB) calorimeters to hadrons, electrons and muons in a wide momentum range from 1 to 350 GeV/c. To our knowledge, this is the widest range of momenta in which any calorimeter system is studied. These tests, carried out at the H2 beam-line at CERN, provide a wealth of information, especially at low energies. We analyze in detail the differences in total calorimeter response to charged pions, kaons, protons and antiprotons and discuss the underlying phenomena. These data will play a crucial role in the thorough understanding of jets in CMS.

Topographic, edaphic, and vegetative controls on plant-available water

Science.gov (United States)

Salli F. Dymond; John B. Bradford; Paul V. Bolstad; Randall K. Kolka; Stephen D. Sebestyen; Thomas M. DeSutter

2017-01-01

Soil moisture varies within landscapes in response to vegetative, physiographic, and climatic drivers, which makes quantifying soil moisture over time and space difficult. Nevertheless, understanding soil moisture dynamics for different ecosystems is critical, as the amount of water in a soil determines a myriad ecosystem services and processes such as net primary...

Do state-of-the-art CMIP5 ESMs accurately represent observed vegetation-rainfall feedbacks? Focus on the Sahel

Science.gov (United States)

Notaro, M.; Wang, F.; Yu, Y.; Mao, J.; Shi, X.; Wei, Y.

2017-12-01

The semi-arid Sahel ecoregion is an established hotspot of land-atmosphere coupling. Ocean-land-atmosphere interactions received considerable attention by modeling studies in response to the devastating 1970s-90s Sahel drought, which models suggest was driven by sea-surface temperature (SST) anomalies and amplified by local vegetation-atmosphere feedbacks. Vegetation affects the atmosphere through biophysical feedbacks by altering the albedo, roughness, and transpiration and thereby modifying exchanges of energy, momentum, and moisture with the atmosphere. The current understanding of these potentially competing processes is primarily based on modeling studies, with biophysical feedbacks serving as a key uncertainty source in regional climate change projections among Earth System Models (ESMs). In order to reduce this uncertainty, it is critical to rigorously evaluate the representation of vegetation feedbacks in ESMs against an observational benchmark in order to diagnose systematic biases and their sources. However, it is challenging to successfully isolate vegetation's feedbacks on the atmosphere, since the atmospheric control on vegetation growth dominates the atmospheric feedback response to vegetation anomalies and the atmosphere is simultaneously influenced by oceanic and terrestrial anomalies. In response to this challenge, a model-validated multivariate statistical method, Stepwise Generalized Equilibrium Feedback Assessment (SGEFA), is developed, which extracts the forcing of a slowly-evolving environmental variable [e.g. SST or leaf area index (LAI)] on the rapidly-evolving atmosphere. By applying SGEFA to observational and remotely-sensed data, an observational benchmark is established for Sahel vegetation feedbacks. In this work, the simulated responses in key atmospheric variables, including evapotranspiration, albedo, wind speed, vertical motion, temperature, stability, and rainfall, to Sahel LAI anomalies are statistically assessed in Coupled Model

Quantifying the Vegetation Health Based on the Resilience in an Arid System

Directory of Open Access Journals (Sweden)

Ranjbar Abolfazl

2018-03-01

Full Text Available Proper management of natural ecosystems is not possible without the knowledge of the health status of its components. Vegetation, as the main component of the ecosystem, plays an important role in its health. One of the key determinants of vegetation health is its resilience in the face of environmental disorders. This research was conducted in parts of the Namakzar-e Khaf watershed in Northeast of South Khorasan Province with the aim of quantifying the vegetative resilience on behalf of the ecosystem health in response to long-term precipitation changes. First, the annual precipitation standardization was performed during a thirty-year period by the SPI method. Then, the average variation in TNDVI index obtained from the Landsat satellite images was examined and the resilience was tested by calculating the four effective factors (amplitude, malleability, damping and hysteresis. According to the results, the amplitude in the survey period was 6.04% and the vegetation has had different values of damping over the years. The most prominent example of vegetation resilience occurred between 1986 and 1996, with malleability of 0.7 and damping of zero. Vegetation in this period, after the elimination of drought effects (1986, has not only returned to the amount of vegetation of reference year with severe precipitation (1996 but also increased by 0.25%. This increase, as the index of hysteresis, has been presented for the first time in the ecosystem health discussion quantitatively in the present study. A set of quantitative calculations showed that despite reduced annual precipitation and drought events, the vegetation has been able to maintain its resilience, which indicates the health of vegetation in the studied ecosystem.

Mapping and exploring variation in post-fire vegetation recovery following mixed severity wildfire using airborne LiDAR.

Science.gov (United States)

Gordon, Christopher E; Price, Owen F; Tasker, Elizabeth M

2017-07-01

There is a public perception that large high-severity wildfires decrease biodiversity and increase fire hazard by homogenizing vegetation composition and increasing the cover of mid-story vegetation. But a growing literature suggests that vegetation responses are nuanced. LiDAR technology provides a promising remote sensing tool to test hypotheses about post-fire vegetation regrowth because vegetation cover can be quantified within different height strata at fine scales over large areas. We assess the usefulness of airborne LiDAR data for measuring post-fire mid-story vegetation regrowth over a range of spatial resolutions (10 × 10 m, 30 × 30 m, 50 × 50 m, 100 × 100 m cell size) and investigate the effect of fire severity on regrowth amount and spatial pattern following a mixed severity wildfire in Warrumbungle National Park, Australia. We predicted that recovery would be more vigorous in areas of high fire severity, because park managers observed dense post-fire regrowth in these areas. Moderate to strong positive associations were observed between LiDAR and field surveys of mid-story vegetation cover between 0.5-3.0 m. Thus our LiDAR survey was an apt representation of on-ground vegetation cover. LiDAR-derived mid-story vegetation cover was 22-40% lower in areas of low and moderate than high fire severity. Linear mixed-effects models showed that fire severity was among the strongest biophysical predictors of mid-story vegetation cover irrespective of spatial resolution. However much of the variance associated with these models was unexplained, presumably because soil seed banks varied at finer scales than our LiDAR maps. Dense patches of mid-story vegetation regrowth were small (median size 0.01 ha) and evenly distributed between areas of low, moderate and high fire severity, demonstrating that high-severity fires do not homogenize vegetation cover. Our results are relevant for ecosystem conservation and fire management because they: indicate

Response matrix Monte Carlo based on a general geometry local calculation for electron transport

International Nuclear Information System (INIS)

Ballinger, C.T.; Rathkopf, J.A.; Martin, W.R.

1991-01-01

A Response Matrix Monte Carlo (RMMC) method has been developed for solving electron transport problems. This method was born of the need to have a reliable, computationally efficient transport method for low energy electrons (below a few hundred keV) in all materials. Today, condensed history methods are used which reduce the computation time by modeling the combined effect of many collisions but fail at low energy because of the assumptions required to characterize the electron scattering. Analog Monte Carlo simulations are prohibitively expensive since electrons undergo coulombic scattering with little state change after a collision. The RMMC method attempts to combine the accuracy of an analog Monte Carlo simulation with the speed of the condensed history methods. Like condensed history, the RMMC method uses probability distributions functions (PDFs) to describe the energy and direction of the electron after several collisions. However, unlike the condensed history method the PDFs are based on an analog Monte Carlo simulation over a small region. Condensed history theories require assumptions about the electron scattering to derive the PDFs for direction and energy. Thus the RMMC method samples from PDFs which more accurately represent the electron random walk. Results show good agreement between the RMMC method and analog Monte Carlo. 13 refs., 8 figs

Density response to central electron heating: theoretical investigations and experimental observations in ASDEX Upgrade

Science.gov (United States)

Angioni, C.; Peeters, A. G.; Garbet, X.; Manini, A.; Ryter, F.; ASDEX Upgrade Team

2004-08-01

Theory of ion temperature gradient (ITG) and trapped electron modes (TEMs) is applied to the study of particle transport in experimental conditions with central electron heating. It is shown that in the unstable domain of TEMs, the electron thermodiffusive flux is directed outwards. By means of such a flux, a mechanism is identified likely to account for density flattening with central electron heating. Theoretical predictions are compared with experimental observations in ASDEX Upgrade. A parameter domain (including L- and H-mode plasmas) is identified, in which flattening with central electron heating is observed in the experiments. In general, this domain turns out to be the same domain in which the dominant plasma instability is a TEM. On the contrary, the dominant instability is an ITG in plasmas whose density profile is not affected significantly by central electron heating. The flattening predicted by quasi-linear theory for low density L-mode plasmas is too small compared to the experimental observations. At very high density, even when the dominant instability is an ITG, electron heating can provide density flattening, via the coupling with the ion heat channel. In these conditions the anomalous diffusivity increases in response to the increased ion heat flux, while the large collisionality makes the anomalous pinch small and the Ware pinch important.

Using endmembers in AVIRIS images to estimate changes in vegetative biomass

Science.gov (United States)

Smith, Milton O.; Adams, John B.; Ustin, Susan L.; Roberts, Dar A.

1992-01-01

Field techniques for estimating vegetative biomass are labor intensive, and rarely are used to monitor changes in biomass over time. Remote-sensing offers an attractive alternative to field measurements; however, because there is no simple correspondence between encoded radiance in multispectral images and biomass, it is not possible to measure vegetative biomass directly from AVIRIS images. Ways to estimate vegetative biomass by identifying community types and then applying biomass scalars derived from field measurements are investigated. Field measurements of community-scale vegetative biomass can be made, at least for local areas, but it is not always possible to identify vegetation communities unambiguously using remote measurements and conventional image-processing techniques. Furthermore, even when communities are well characterized in a single image, it typically is difficult to assess the extent and nature of changes in a time series of images, owing to uncertainties introduced by variations in illumination geometry, atmospheric attenuation, and instrumental responses. Our objective is to develop an improved method based on spectral mixture analysis to characterize and identify vegetative communities, that can be applied to multi-temporal AVIRIS and other types of images. In previous studies, multi-temporal data sets (AVIRIS and TM) of Owens Valley, CA were analyzed and vegetation communities were defined in terms of fractions of reference (laboratory and field) endmember spectra. An advantage of converting an image to fractions of reference endmembers is that, although fractions in a given pixel may vary from image to image in a time series, the endmembers themselves typically are constant, thus providing a consistent frame of reference.

Response of the CALICE Si-W Electromagnetic Calorimeter Physics Prototype to Electrons

CERN Document Server

Adloff, C.; Repond, J.; Yu, J.; Eigen, G.; Hawkes, C.M.; Mikami, Y.; Miller, O.; Watson, N.K.; Wilson, J.A.; Goto, T.; Mavromanolakis, G.; Thomson, M.A.; Ward, D.R.; Yan, W.; Benchekroun, D.; Hoummada, A.; Krim, M.; Benyamna, M.; Boumediene, D.; Brun, N.; Carloganu, C.; Gay, P.; Morisseau, F.; Blazey, G.C.; Chakraborty, D.; Dyshkant, A.; Francis, K.; Hedin, D.; Lima, G.; Zutshi, V.; Hostachy, J.-Y.; Morin, L.; D'Ascenzo, N.; Cornett, U.; David, D.; Fabbri, R.; Falley, G.; Gadow, K.; Garutti, E.; Gottlicher, P.; Jung, T.; Karstensen, S.; Korbel, V.; Lucaci-Timoce, A.-I.; Lutz, B.; Meyer, N.; Morgunov, V.; Reinecke, M.; Sefkow, F.; Smirnov, P.; Vargas-Trevino, A.; Wattimena, N.; Wendt, O.; Feege, N.; Groll, M.; Haller, J.; Heuer, R.-D.; Richter, S.; Samson, J.; Kaplan, A.; Schultz-Coulon, H.-Ch.; Shen, W.; Tadday, A.; Bilki, B.; Norbeck, E.; Onel, Y.; Kim, E.J.; Baek, N.I.; Kim, D-W.; Lee, K.; Lee, S.C.; Kawagoe, K.; Tamura, Y.; Bowerman, D.A.; Dauncey, P.D.; Magnan, A.-M.; Yilmaz, H.; Zorba, O.; Bartsch, V.; Postranecky, M.; Warren, M.; Wing, M.; Faucci Giannelli, M.; Green, M.G.; Salvatore, F.; Bedjidian, M.; Kieffer, R.; Laktineh, I.; Bailey, D.S.; Barlow, R.J.; Kelly, M.; Thompson, R.J.; Danilov, M.; Tarkovsky, E.; Baranova, N.; Karmanov, D.; Korolev, M.; Merkin, M.; Voronin, A.; Frey, A.; Lu, S.; Prothmann, K.; Simon, F.; Bouquet, B.; Callier, S.; Cornebise, P.; Fleury, J.; Li, H.; Richard, F.; de la Taille, Ch.; Poeschl, R.; Raux, L.; Ruan, M.; Seguin-Moreau, N.; Wicek, F.; Anduze, M.; Boudry, V.; Brient, J-C.; Gaycken, G.; Mora de Freitas, P.; Musat, G.; Reinhard, M.; Rouge, A.; Vanel, J-Ch.; Videau, H.; Park, K-H.; Zacek, J.; Cvach, J.; Gallus, P.; Havranek, M.; Janata, M.; Marcisovsky, M.; Polak, I.; Popule, J.; Tomasek, L.; Tomasek, M.; Ruzicka, P.; Sicho, P.; Smolik, J.; Vrba, V.; Zalesak, J.; Belhorma, B.; Belmir, M.; Nam, S.W.; Park, I.H.; Yang, J.; Chai, J.-S.; Kim, J.-T.; Kim, G.-B.; Kang, J.; Kwon, Y.-J.

2009-01-01

A prototype Silicon-Tungsten electromagnetic calorimeter (ECAL) for an International Linear Collider (ILC) detector was installed and tested during summer and autumn 2006 at CERN. The detector had 6480 silicon pads of dimension 1x1 cm^2. Data were collected with electron beams in the energy range 6 to 45 GeV. The analysis described in this paper focuses on electromagnetic shower reconstruction and characterises the ECAL response to electrons in terms of energy resolution and linearity. The detector is linear to within approximately the 1% level and has a relative energy resolution of (16.6 +- 0.1)/ \\sqrt{E(GeV}) + 1.1 +- 0.1 (%). The spatial uniformity and the time stability of the ECAL are also addressed.

Genetic variation in the hTAS2R38 taste receptor and brassica vegetable intake

DEFF Research Database (Denmark)

Gorovic, Nela; Afzal, Shoaib; Tjonneland, Anne

2011-01-01

The human TAS2R38 receptor is believed to be partly responsible for the ability to taste phenylthiocarbamide (PTC), a bitter compound very similar to the bitter glucosinolates found in brassica vegetables. These vegetables and their active compounds have chemo-protective properties. This study...... investigated the relationship between genetic variation in the hTAS2R38 receptor and the actual consumption of brassica vegetables with the hypothesis that taster status was associated with intake of these vegetables. Furthermore, secondary intake information on alcohol, chocolate, coffee, smoking, BMI...... on their brassica vegetables intake from the upper quartile (>= a parts per thousand yen23 g/day) and the lower quartile (brassicas from a randomly selected sub-cohort of DCH. DNA was analysed for three functional SNPs in the hTAS2R38 gene. The hTAS2R38...

Review of Vegetable Market Development in China

Institute of Scientific and Technical Information of China (English)

Chaoping; LUO; Yuandong; NI; Qiong; ZHAI

2013-01-01

This paper has reviewed vegetable market development from vegetable circulation system, the develop history of the liberalize vegetable market and the growth of the vegetable wholesale market in China. From the development of vegetables market in China and its characteristics: the development of vegetable market in China is related to vegetable market system, the change of institution, some technology development and infrastructure. this paper has put forward some related measures to perfect the vegetable market and improve the vegetable circulation efficiency in China.

Evaporative cooling over the Tibetan Plateau induced by vegetation growth

Science.gov (United States)

Shen, Miaogen; Piao, Shilong; Jeong, Su-Jong; Zhou, Liming; Zeng, Zhenzhong; Ciais, Philippe; Chen, Deliang; Huang, Mengtian; Jin, Chun-Sil; Li, Laurent Z. X.; Li, Yue; Myneni, Ranga B.; Yang, Kun; Zhang, Gengxin; Zhang, Yangjian; Yao, Tandong

2015-01-01

In the Arctic, climate warming enhances vegetation activity by extending the length of the growing season and intensifying maximum rates of productivity. In turn, increased vegetation productivity reduces albedo, which causes a positive feedback on temperature. Over the Tibetan Plateau (TP), regional vegetation greening has also been observed in response to recent warming. Here, we show that in contrast to arctic regions, increased growing season vegetation activity over the TP may have attenuated surface warming. This negative feedback on growing season vegetation temperature is attributed to enhanced evapotranspiration (ET). The extra energy available at the surface, which results from lower albedo, is efficiently dissipated by evaporative cooling. The net effect is a decrease in daily maximum temperature and the diurnal temperature range, which is supported by statistical analyses of in situ observations and by decomposition of the surface energy budget. A daytime cooling effect from increased vegetation activity is also modeled from a set of regional weather research and forecasting (WRF) mesoscale model simulations, but with a magnitude smaller than observed, likely because the WRF model simulates a weaker ET enhancement. Our results suggest that actions to restore native grasslands in degraded areas, roughly one-third of the plateau, will both facilitate a sustainable ecological development in this region and have local climate cobenefits. More accurate simulations of the biophysical coupling between the land surface and the atmosphere are needed to help understand regional climate change over the TP, and possible larger scale feedbacks between climate in the TP and the Asian monsoon system. PMID:26170316

Information needs for the rapid response team electronic clinical tool.

Science.gov (United States)

Barwise, Amelia; Caples, Sean; Jensen, Jeffrey; Pickering, Brian; Herasevich, Vitaly

2017-10-02

Information overload in healthcare is dangerous. It can lead to critical errors and delays. During Rapid Response Team (RRT) activations providers must make decisions quickly to rescue patients from physiological deterioration. In order to understand the clinical data required and how best to present that information in electronic systems we aimed to better assess the data needs of providers on the RRT when they respond to an event. A web based survey to evaluate clinical data requirements was created and distributed to all RRT providers at our institution. Participants were asked to rate the importance of each data item in guiding clinical decisions during a RRT event response. There were 96 surveys completed (24.5% response rate) with fairly even distribution throughout all clinical roles on the RRT. Physiological data including heart rate, respiratory rate, and blood pressure were ranked by more than 80% of responders as being critical information. Resuscitation status was also considered critically useful by more than 85% of providers. There is a limited dataset that is considered important during an RRT. The data is widely available in EMR. The findings from this study could be used to improve user-centered EMR interfaces.

Monitoring pesticides residues and contaminants for some leafy vegetables at the market level

International Nuclear Information System (INIS)

Ibrahim, A. B. H.

2004-03-01

Pesticide residues and contaminants in selected leafy vegetables, namely (lettuce, garden rocket and salad onion) were monitored at market level in Riyadh City in Saudi Arabia, during the period june to july 2001. Fifteen samples of vegetables from the City vegetable market of Riyadh were collected and subjected to multi-pesticide residue detection and analysis by gas chromatography with mass spectrometer and electron capture detectors (GC/MS,ECD). Results of sample extracts analysis showed that the two vegetables of: garden rocket and salad onion contain pesticide residues and contaminants which have no Maximum Residue Limits (MRL) prescribed by Codex Alimentarius Commission (CAC) collaborate with World Health and Food and Agriculture Organizations (WHO/FAO). Whereas lettuce vegetable was found free of any identified pesticide residues or contaminants. Garden rocket was shown to contain dibutyl phthalate (0.04 ppm)-steryl chloride (0.02 ppm) tridecane (0.06 ppm)-hexadecane (0.07 ppm)-BIS (ethylhexyl) phthalate (0.006 ppm) and pyridinium, 1-hexyl chloride (0.01 ppm). The salad onion was found to contain 9-octadecanamide (0.13 ppm)-tridecane (0.15 ppm) and tetradecane (0.16 ppm). There are no established MRL s for these pesticides and contaminants detected in garden rocket and salad onion, although when impacts on human health were reviewed some of them were found probably hazardous. (Author)

Analyzing the Velocity of Vegetation Phenology Over the Tibetan Plateau Using Gimms NDVI3g Data

Science.gov (United States)

Zhou, Y. K.

2018-05-01

Global environmental change is rapidly altering the dynamics of terrestrial vegetation, and phenology is a classic proxy to detect the response of vegetation to the changes. On the Tibetan Plateau, the earlier spring and delayed autumn vegetation phenology is widely reported. Remotely sensed NDVI can serve as a good data source for vegetation phenology study. Here GIMMS NDVI3g data was used to detect vegetation phenology status on the Tibetan Plateau. The spatial and temporal gradients are combined to depict the velocity of vegetation expanding process. This velocity index represents the instantaneous local velocity along the Earth's surface needed to maintain constant vegetation condition. This study found that NDVI velocity show a complex spatial pattern. A considerable number of regions display a later starting of growing season (SOS) and earlier end of growing season (EOS) reflected by the velocity change, particularly in the central part of the plateau. Nearly 74 % vegetation experienced a shortened growing season length. Totally, the magnitude of the phenology velocity is at a small level that reveals there is not a significant variation of vegetation phenology under the climate change context.

Natural Organochlorines as Precursors of 3-Monochloropropanediol Esters in Vegetable Oils.

Science.gov (United States)

Tiong, Soon Huat; Saparin, Norliza; Teh, Huey Fang; Ng, Theresa Lee Mei; Md Zain, Mohd Zairey Bin; Neoh, Bee Keat; Md Noor, Ahmadilfitri; Tan, Chin Ping; Lai, Oi Ming; Appleton, David Ross

2018-01-31

During high-temperature refining of vegetable oils, 3-monochloropropanediol (3-MCPD) esters, possible carcinogens, are formed from acylglycerol in the presence of a chlorine source. To investigate organochlorine compounds in vegetable oils as possible precursors for 3-MCPD esters, we tested crude palm, soybean, rapeseed, sunflower, corn, coconut, and olive oils for the presence of organochlorine compounds. Having found them in all vegetable oils tested, we focused subsequent study on oil palm products. Analysis of the chlorine isotope mass pattern exhibited in high-resolution mass spectrometry enabled organochlorine compound identification in crude palm oils as constituents of wax esters, fatty acid, diacylglycerols, and sphingolipids, which are produced endogenously in oil palm mesocarp throughout ripening. Analysis of thermal decomposition and changes during refining suggested that these naturally present organochlorine compounds in palm oils and perhaps in other vegetable oils are precursors of 3-MCPD esters. Enrichment and dose-response showed a linear relationship to 3-MCPD ester formation and indicated that the sphingolipid-based organochlorine compounds are the most active precursors of 3-MCPD esters.

Synchronicity in elevation range shifts among small mammal and vegetation over the last century is stronger for omnivores

NARCIS (Netherlands)

Ferreira Dos Santos, Maria Joao; Thorne, James; Moritz, Craig

2015-01-01

In mountain ecosystems, species can be said to respond synchronously to environmental change when the elevation ranges of vegetation types and their associated vertebrates expand or contract in the same direction. Conversely, the response is asynchronous when the elevation ranges of vegetation types

Electron dominated thermoelectric response in MNiSn (M: Ti, Zr, Hf) half-Heusler alloys

KAUST Repository

Gandi, Appala

2016-05-09

We solve the transport equations of the electrons and phonons to understand the thermoelectric behaviour of the technologically important half-Heusler alloys MNiSn (M: Ti, Zr, Hf). Doping is simulated within the rigid band approximation. We clarify the origin of the electron dominated thermoelectric response and determine the carrier concentrations with maximal figures of merit. The phonon mean free path is studied to calculate the grain size below which grain refinement methods can enforce ballistic heat conduction to enhance the figure of merit. © The Owner Societies 2016.

Electron dominated thermoelectric response in MNiSn (M: Ti, Zr, Hf) half-Heusler alloys

KAUST Repository

Gandi, Appala; Schwingenschlö gl, Udo

2016-01-01

We solve the transport equations of the electrons and phonons to understand the thermoelectric behaviour of the technologically important half-Heusler alloys MNiSn (M: Ti, Zr, Hf). Doping is simulated within the rigid band approximation. We clarify the origin of the electron dominated thermoelectric response and determine the carrier concentrations with maximal figures of merit. The phonon mean free path is studied to calculate the grain size below which grain refinement methods can enforce ballistic heat conduction to enhance the figure of merit. © The Owner Societies 2016.

An ecohydrological model for studying groundwater-vegetation interactions in wetlands

Science.gov (United States)

Chui, Ting Fong May; Low, Swee Yang; Liong, Shie-Yui

2011-10-01

SummaryDespite their importance to the natural environment, wetlands worldwide face drastic degradation from changes in land use and climatic patterns. To help preservation efforts and guide conservation strategies, a clear understanding of the dynamic relationship between coupled hydrology and vegetation systems in wetlands, and their responses to engineering works and climate change, is needed. An ecohydrological model was developed in this study to address this issue. The model combines a hydrology component based on the Richards' equation for characterizing variably saturated groundwater flow, with a vegetation component described by Lotka-Volterra equations tailored for plant growth. Vegetation is represented by two characteristic wetland herbaceous plant types which differ in their flood and drought resistances. Validation of the model on a study site in the Everglades demonstrated the capability of the model in capturing field-measured water table and transpiration dynamics. The model was next applied on a section of the Nee Soon swamp forest, a tropical wetland in Singapore, for studying the impact of possible drainage works on the groundwater hydrology and native vegetation. Drainage of 10 m downstream of the wetland resulted in a localized zone of influence within half a kilometer from the drainage site with significant adverse impacts on groundwater and biomass levels, indicating a strong need for conservation. Simulated water table-plant biomass relationships demonstrated the capability of the model in capturing the time-lag in biomass response to water table changes. To test the significance of taking plant growth into consideration, the performance of the model was compared to one that substituted the vegetation component with a pre-specified evapotranspiration rate. Unlike its revised counterpart, the original ecohydrological model explicitly accounted for the drainage-induced plant biomass decrease and translated the resulting reduced transpiration

Holocene Vegetation Succession and Response to Climate Change on the South Bank of the Heilongjiang-Amur River, Mohe County, Northeast China

Directory of Open Access Journals (Sweden)

Chao Zhao

2016-01-01

Full Text Available Pollen samples from peat sediments on the south bank of the Heilongjiang River in northern Northeast China (NE China were analyzed to reconstruct the historical response of vegetation to climate change since 7800 cal yr BP. Vegetation was found to have experienced five successions from cold-temperate mixed coniferous and broadleaved forest to forest-steppe, steppe-woodland, steppe, and finally meadow-woodland. From 7800 to 7300 cal yr BP, the study area was warmer than present, and Betula, Larix, and Picea-dominated mixed coniferous and broadleaved forests thrived. Two cooling events at 7300 cal yr BP and 4500 cal yr BP led to a decrease in Betula and other broadleaved forests, whereas herbs of Poaceae expanded, leading to forest-steppe and then steppe-woodland environments. After 2500 cal yr BP, reduced temperatures and a decrease in evaporation rates are likely to have resulted in permafrost expansion and surface ponding, with meadow and isolated coniferous forests developing a resistance to the cold-wet environment. The Holocene warm period in NE China (7800–7300 cal yr BP could have resulted in a strengthening of precipitation in northernmost NE China and encouraged the development of broadleaved forests.

Regional vegetation dynamics and its response to climate change—a case study in the Tao River Basin in Northwestern China

International Nuclear Information System (INIS)

Li, Changbin; Yang, Linshan; Wang, Shuaibing; Yang, Wenjin; Zhu, Gaofeng; Qi, Jiaguo; Zou, Songbing; Zhang, Feng

2014-01-01

The 30-year normalized-difference vegetation index (NDVI) time series from AVHRR/MODIS satellite sensors was used in this study to assess the regional vegetation dynamic changes in the Tao River Basin, which cuts across the Eastern Tibetan Plateau (ETP) and the Southwestern Loess Plateau (SLP). First, principal component and correlation analyses were carried out to determine the key climatic variables driving ecological change in the region. Then, regression models were tested to correlate NDVI with the selected climatic variables to determine their predictive power. Finally, Sen’s slope method was used to determine how terrestrial vegetation has responded to regional climate change in the region. The results indicated an average winter season NDVI value of 0.14 in the ETP but only 0.04 in the SLP. Primarily driven by increasing temperature, vegetation growth has generally been enhanced since 1981; spring NDVI increased by 0.03 every 10 years in the ETP and 0.02 in the SLP. Further, results from trend analyses suggest vegetation growth in the ETP shifted to earlier-start and earlier-end dates, however in the SLP, the growing season has been extended with an earlier-start and later-end date. The precipitation threshold for vegetation germination, measured by the cumulative spring rainfall, was found to be 44 mm for both the ETP and SLP. (paper)

Spectral Discrimination of Vegetation Classes in Ice-Free Areas of Antarctica

Directory of Open Access Journals (Sweden)

María Calviño-Cancela

2016-10-01

Full Text Available Detailed monitoring of vegetation changes in ice-free areas of Antarctica is crucial to determine the effects of climate warming and increasing human presence in this vulnerable ecosystem. Remote sensing techniques are especially suitable in this distant and rough environment, with high spectral and spatial resolutions needed owing to the patchiness and similarity between vegetation elements. We analyze the reflectance spectra of the most representative vegetation elements in ice-free areas of Antarctica to assess the potential for discrimination. This research is aimed as a basis for future aircraft/satellite research for long-term vegetation monitoring. The study was conducted in the Barton Peninsula, King George Island. The reflectance of ground patches of different types of vegetation or bare ground (c. 0.25 m 2 , n = 30 patches per class was recorded with a spectrophotometer measuring between 340 nm to 1025 nm at a resolution of 0.38 n m . We used Linear Discriminant Analysis (LDA to classify the cover classes according to reflectance spectra, after reduction of the number of bands using Principal Component Analysis (PCA. The first five principal components explained an accumulated 99.4% of the total variance and were added to the discriminant function. The LDA classification resulted in c. 92% of cases correctly classified (a hit ratio 11.9 times greater than chance. The most important region for discrimination was the visible and near ultraviolet (UV, with the relative importance of spectral bands steeply decreasing in the Near Infra-Red (NIR region. Our study shows the feasibility of discriminating among representative taxa of Antarctic vegetation using their spectral patterns in the near UV, visible and NIR. The results are encouraging for hyperspectral vegetation mapping in Antarctica, which could greatly facilitate monitoring vegetation changes in response to a changing environment, reducing the costs and environmental impacts of

Balkan Vegetation Database

NARCIS (Netherlands)

Vassilev, Kiril; Pedashenko, Hristo; Alexandrova, Alexandra; Tashev, Alexandar; Ganeva, Anna; Gavrilova, Anna; Gradevska, Asya; Assenov, Assen; Vitkova, Antonina; Grigorov, Borislav; Gussev, Chavdar; Filipova, Eva; Aneva, Ina; Knollová, Ilona; Nikolov, Ivaylo; Georgiev, Georgi; Gogushev, Georgi; Tinchev, Georgi; Pachedjieva, Kalina; Koev, Koycho; Lyubenova, Mariyana; Dimitrov, Marius; Apostolova-Stoyanova, Nadezhda; Velev, Nikolay; Zhelev, Petar; Glogov, Plamen; Natcheva, Rayna; Tzonev, Rossen; Boch, Steffen; Hennekens, Stephan M.; Georgiev, Stoyan; Stoyanov, Stoyan; Karakiev, Todor; Kalníková, Veronika; Shivarov, Veselin; Russakova, Veska; Vulchev, Vladimir

2016-01-01

The Balkan Vegetation Database (BVD; GIVD ID: EU-00-019; http://www.givd.info/ID/EU-00- 019) is a regional database that consists of phytosociological relevés from different vegetation types from six countries on the Balkan Peninsula (Albania, Bosnia and Herzegovina, Bulgaria, Kosovo, Montenegro

Importance of vegetation dynamics for future terrestrial carbon cycling

International Nuclear Information System (INIS)

Ahlström, Anders; Smith, Benjamin; Xia, Jianyang; Luo, Yiqi; Arneth, Almut

2015-01-01

Terrestrial ecosystems currently sequester about one third of anthropogenic CO 2 emissions each year, an important ecosystem service that dampens climate change. The future fate of this net uptake of CO 2 by land based ecosystems is highly uncertain. Most ecosystem models used to predict the future terrestrial carbon cycle share a common architecture, whereby carbon that enters the system as net primary production (NPP) is distributed to plant compartments, transferred to litter and soil through vegetation turnover and then re-emitted to the atmosphere in conjunction with soil decomposition. However, while all models represent the processes of NPP and soil decomposition, they vary greatly in their representations of vegetation turnover and the associated processes governing mortality, disturbance and biome shifts. Here we used a detailed second generation dynamic global vegetation model with advanced representation of vegetation growth and mortality, and the associated turnover. We apply an emulator that describes the carbon flows and pools exactly as in simulations with the full model. The emulator simulates ecosystem dynamics in response to 13 different climate or Earth system model simulations from the Coupled Model Intercomparison Project Phase 5 ensemble under RCP8.5 radiative forcing. By exchanging carbon cycle processes between these 13 simulations we quantified the relative roles of three main driving processes of the carbon cycle; (I) NPP, (II) vegetation dynamics and turnover and (III) soil decomposition, in terms of their contribution to future carbon (C) uptake uncertainties among the ensemble of climate change scenarios. We found that NPP, vegetation turnover (including structural shifts, wild fires and mortality) and soil decomposition rates explained 49%, 17% and 33%, respectively, of uncertainties in modelled global C-uptake. Uncertainty due to vegetation turnover was further partitioned into stand-clearing disturbances (16%), wild fires (0%), stand

Microbiological Spoilage of Fruits and Vegetables

Science.gov (United States)

Barth, Margaret; Hankinson, Thomas R.; Zhuang, Hong; Breidt, Frederick

Consumption of fruit and vegetable products has dramatically increased in the United States by more than 30% during the past few decades. It is also estimated that about 20% of all fruits and vegetables produced is lost each year due to spoilage. The focus of this chapter is to provide a general background on microbiological spoilage of fruit and vegetable products that are organized in three categories: fresh whole fruits and vegetables, fresh-cut fruits and vegetables, and fermented or acidified vegetable products. This chapter will address characteristics of spoilage microorganisms associated with each of these fruit and vegetable categories including spoilage mechanisms, spoilage defects, prevention and control of spoilage, and methods for detecting spoilage microorganisms.

A Monte Carlo simulation of the microdosimetric response for thick gas electron multiplier

International Nuclear Information System (INIS)

Hanu, A.; Byun, S.H.; Prestwich, W.V.

2010-01-01

The neutron microdosimetric responses of the thick gas electron multiplier (THGEM) detector were simulated. The THGEM is a promising device for microdosimetry, particularly for measuring the dose spectra of intense radiation fields and for collecting two-dimensional microdosimetric distributions. To investigate the response of the prototype THGEM microdosimetric detector, a simulation was developed using the Geant4 Monte Carlo code. The simulation calculates the deposited energy in the detector sensitive volume for an incident neutron beam. Both neutron energy and angular responses were computed for various neutron beam conditions. The energy response was compared with the reported experimental microdosimetric spectra as well as the evaluated fluence-to-kerma conversion coefficients. The effects of using non-tissue equivalent materials were also investigated by comparing the THGEM detector response with the response of an ideal detector in identical neutron field conditions. The result of the angular response simulations revealed severe angular dependencies for neutron energies above 100 keV. The simulation of a modified detector design gave an angular response pattern close to the ideal case, showing a fluctuation of less than 10% over the entire angular range.

Click chemistry approach to conventional vegetable tanning process: accelerated method with improved organoleptic properties.

Science.gov (United States)

Krishnamoorthy, Ganesan; Ramamurthy, Govindaswamy; Sadulla, Sayeed; Sastry, Thotapalli Parvathaleswara; Mandal, Asit Baran

2014-09-01

Click chemistry approaches are tailored to generate molecular building blocks quickly and reliably by joining small units together selectively and covalently, stably and irreversibly. The vegetable tannins such as hydrolyzable and condensed tannins are capable to produce rather stable radicals or inhibit the progress of radicals and are prone to oxidations such as photo and auto-oxidation, and their anti-oxidant nature is well known. A lot remains to be done to understand the extent of the variation of leather stability, color variation (lightening and darkening reaction of leather), and poor resistance to water uptake for prolonged periods. In the present study, we have reported click chemistry approaches to accelerated vegetable tanning processes based on periodates catalyzed formation of oxidized hydrolysable and condensed tannins for high exhaustion with improved properties. The distribution of oxidized vegetable tannin, the thermal stability such as shrinkage temperature (T s) and denaturation temperature (T d), resistance to collagenolytic activities, and organoleptic properties of tanned leather as well as the evaluations of eco-friendly characteristics were investigated. Scanning electron microscopic analysis indicates the cross section of tightness of the leather. Differential scanning calorimetric analysis shows that the T d of leather is more than that of vegetable tanned or equal to aldehyde tanned one. The leathers exhibited fullness, softness, good color, and general appearance when compared to non-oxidized vegetable tannin. The developed process benefits from significant reduction in total solids and better biodegradability in the effluent, compared to non-oxidized vegetable tannins.

Explaining fruit and vegetable intake using a consumer marketing tool.

Science.gov (United States)

Della, Lindsay J; Dejoy, David M; Lance, Charles E

2009-10-01

In response to calls to reinvent the 5 A Day fruit and vegetable campaign, this study assesses the utility of VALS, a consumer-based audience segmentation tool that divides the U.S. population into groups leading similar lifestyles. The study examines whether the impact of theory of planned behavior (TPB) constructs varies across VALS groups in a cross-sectional sample of 1,588 U.S. adults. In a multigroup structural equation model, the VALS audience group variable moderated latent TPB relationships. Attitudes, subjective norms, and perceived behavioral control explained 57% to 70% of the variation in intention to eat fruit and vegetables across 5 different VALS groups. Perceived behavioral control and intention also predicted self-reported consumption behavior (R2 = 20% to 71% across VALS groups). Bivariate z tests were calculated to determine statistical differences in parameter estimates across groups. Nine of the bivariate z tests were statistically significant (p audiences for fruit and vegetable consumption messaging.

Multi-scale associations between vegetation cover and woodland bird communities across a large agricultural region.

Directory of Open Access Journals (Sweden)

Karen Ikin

Full Text Available Improving biodiversity conservation in fragmented agricultural landscapes has become an important global issue. Vegetation at the patch and landscape-scale is important for species occupancy and diversity, yet few previous studies have explored multi-scale associations between vegetation and community assemblages. Here, we investigated how patch and landscape-scale vegetation cover structure woodland bird communities. We asked: (1 How is the bird community associated with the vegetation structure of woodland patches and the amount of vegetation cover in the surrounding landscape? (2 Do species of conservation concern respond to woodland vegetation structure and surrounding vegetation cover differently to other species in the community? And (3 Can the relationships between the bird community and the woodland vegetation structure and surrounding vegetation cover be explained by the ecological traits of the species comprising the bird community? We studied 103 woodland patches (0.5 - 53.8 ha over two time periods across a large (6,800 km(2 agricultural region in southeastern Australia. We found that both patch vegetation and surrounding woody vegetation cover were important for structuring the bird community, and that these relationships were consistent over time. In particular, the occurrence of mistletoe within the patches and high values of woody vegetation cover within 1,000 ha and 10,000 ha were important, especially for bird species of conservation concern. We found that the majority of these species displayed similar, positive responses to patch and landscape vegetation attributes. We also found that these relationships were related to the foraging and nesting traits of the bird community. Our findings suggest that management strategies to increase both remnant vegetation quality and the cover of surrounding woody vegetation in fragmented agricultural landscapes may lead to improved conservation of bird communities.

Lake Bathymetric Aquatic Vegetation

Data.gov (United States)

Minnesota Department of Natural Resources — Aquatic vegetation represented as polygon features, coded with vegetation type (emergent, submergent, etc.) and field survey date. Polygons were digitized from...

Effects of vegetation structure on biomass accumulation in a Balanced Optimality Structure Vegetation Model (BOSVM v1.0

Directory of Open Access Journals (Sweden)

Z. Yin

2014-05-01

Full Text Available A myriad of interactions exist between vegetation and local climate for arid and semi-arid regions. Vegetation function, structure and individual behavior have large impacts on carbon–water–energy balances, which consequently influence local climate variability that, in turn, feeds back to the vegetation. In this study, a conceptual vegetation structure scheme is formulated and tested in the new Balanced Optimality Structure Vegetation Model (BOSVM to explore the importance of vegetation structure and vegetation adaptation to water stress on equilibrium biomass states. Surface energy, water and carbon fluxes are simulated for a range of vegetation structures across a precipitation gradient in West Africa and optimal vegetation structures that maximize biomass for each precipitation regime are determined. Two different strategies of vegetation adaptation to water stress are included. Under dry conditions vegetation tries to maximize the water use efficiency and leaf area index as it tries to maximize carbon gain. However, a negative feedback mechanism in the vegetation–soil water system is found as the vegetation also tries to minimize its cover to optimize the surrounding bare ground area from which water can be extracted, thereby forming patches of vertical vegetation. Under larger precipitation, a positive feedback mechanism is found in which vegetation tries to maximize its cover as it then can reduce water loss from bare soil while having maximum carbon gain due to a large leaf area index. The competition between vegetation and bare soil determines a transition between a "survival" state to a "growing" state.

Potential nitrogen critical loads for northern Great Plains grassland vegetation

Science.gov (United States)

Symstad, Amy J.; Smith, Anine T.; Newton, Wesley E.; Knapp, Alan K.

2015-01-01

The National Park Service is concerned that increasing atmospheric nitrogen deposition caused by fossil fuel combustion and agricultural activities could adversely affect the northern Great Plains (NGP) ecosystems in its trust. The critical load concept facilitates communication between scientists and policy makers or land managers by translating the complex effects of air pollution on ecosystems into concrete numbers that can be used to inform air quality targets. A critical load is the exposure level below which significant harmful effects on sensitive elements of the environment do not occur. A recent review of the literature suggested that the nitrogen critical load for Great Plains vegetation is 10-25 kg N/ha/yr. For comparison, current atmospheric nitrogen deposition in NGP National Park Service (NPS) units ranges from ~4 kg N/ha/yr in the west to ~13 kg N/ha/yr in the east. The suggested critical load, however, was derived from studies far outside of the NGP, and from experiments investigating nitrogen loads substantially higher than current atmospheric deposition in the region.Therefore, to better determine the nitrogen critical load for sensitive elements in NGP parks, we conducted a four-year field experiment in three northern Great Plains vegetation types at Badlands and Wind Cave National Parks. The vegetation types were chosen because of their importance in NGP parks, their expected sensitivity to nitrogen addition, and to span a range of natural fertility. In the experiment, we added nitrogen at rates ranging from below current atmospheric deposition (2.5 kg N/ha/yr) to far above those levels but commensurate with earlier experiments (100 kg N/ha/yr). We measured the response of a variety of vegetation and soil characteristics shown to be sensitive to nitrogen addition in other studies, including plant biomass production, plant tissue nitrogen concentration, plant species richness and composition, non-native species abundance, and soil inorganic

Bonneville Power Administration Transmission System Vegetation Management Program - Final Environmental Impact Statement

Energy Technology Data Exchange (ETDEWEB)

N/A

2000-06-23

Bonneville is responsible for maintaining a network of 24,000 kilometers (km) or 15,000 miles (mi.) of electric transmission lines and 350 substations in a region of diverse vegetation. This vegetation can interfere with electric power flow, pose safety problems for us and the public, and interfere with our ability to maintain these facilities. We need to (1) keep vegetation away from our electric facilities; (2) increase our program efficiency and consistency; (3) review herbicide use (under increased public scrutiny); and (4) maximize the range of tools we can use while minimizing environmental impact (Integrated Vegetation Management). This Final Environmental Impact Statement (FEIS) establishes Planning Steps for managing vegetation for specific projects (to be tiered to this Environmental Impact Statement (EIS)). In addition to No Action (current practice), alternatives are presented for Rights-of-way, Electric Yards, and Non-electric Facilities (landscaping, work yards). Four vegetation control methods are analyzed manual, mechanical, herbicide, and biological. Also evaluated are 23 herbicide active ingredients and 4 herbicide application techniques (spot, localized, broadcast, and aerial). For rights-of-way, we consider three sets of alternatives: alternative management approaches (time-driven or establishing low-growing plant communities); alternative method packages; and, if herbicides are in a methods package, alternative vegetation selections (noxious weeds, deciduous, or any vegetation). For electric yards, one herbicide-use alternative is considered. For non-electric facilities, two method package alternatives are considered. For rights-of-way, the environmentally preferred alternative(s) would use manual, mechanical, and biological control methods, as well as spot and localized herbicide applications for noxious and deciduous plant species; the BPA-preferred alternative(s) would add broadcast and aerial herbicide applications, and would use herbicides

Add More Vegetables to Your Day: 10 Tips to Help You Eat More Vegetables

Science.gov (United States)

... sip on some vegetable soup Heat it and eat it. Try tomato, butternut squash, or garden vegetable soup. Look for reduced- or low-sodium soups. Make your own soups with a low-sodium broth and your favorite vegetables. 8 while you’re out If dinner is away from home, no need to worry. ...