Seasonal Course Research Articles

Characterisation of short-term extreme methane fluxes related to non-turbulent mixing above an Arctic permafrost ecosystem

Abstract. Methane (CH4) emissions from biogenic sources, such as Arctic permafrost wetlands, are associated with large uncertainties because of the high variability of fluxes in both space and time. This variability poses a challenge to monitoring CH4 fluxes with the eddy covariance (EC) technique, because this approach requires stationary signals from spatially homogeneous sources. Episodic outbursts of CH4 emissions, i.e. triggered by spontaneous outgassing of bubbles or venting of methane-rich air from lower levels due to shifts in atmospheric conditions, are particularly challenging to quantify. Such events typically last for only a few minutes, which is much shorter than the common averaging interval for EC (30 min). The steady-state assumption is jeopardised, which potentially leads to a non-negligible bias in the CH4 flux. Based on data from Chersky, NE Siberia, we tested and evaluated a flux calculation method based on wavelet analysis, which, in contrast to regular EC data processing, does not require steady-state conditions and is allowed to obtain fluxes over averaging periods as short as 1 min. Statistics on meteorological conditions before, during, and after the detected events revealed that it is atmospheric mixing that triggered such events rather than CH4 emission from the soil. By investigating individual events in more detail, we identified a potential influence of various mesoscale processes like gravity waves, low-level jets, weather fronts passing the site, and cold-air advection from a nearby mountain ridge as the dominating processes. The occurrence of extreme CH4 flux events over the summer season followed a seasonal course with a maximum in early August, which is strongly correlated with the maximum soil temperature. Overall, our findings demonstrate that wavelet analysis is a powerful method for resolving highly variable flux events on the order of minutes, and can therefore support the evaluation of EC flux data quality under non-steady-state conditions.

Daily Maximum Temperatures Induce Lagged Effects on Leaf Unfolding in Temperate Woody Species Across Large Elevational Gradients.

The timing of leaf unfolding in temperate woody species is predominantly controlled by the seasonal course of temperature in late winter and early spring. However, quantifying lagged temperature effects on spring phenology is still challenging. Here, we aimed at investigating lagged and potentially non-linear effects of daily maximum temperatures on the probability of leaf unfolding in temperate woody species growing across large elevational gradients. We analyzed 5280 observations of leaf-out time of four tree species (European beech, horse chestnut, European larch, Norway spruce) and one shrub species (common hazel) that were recorded by volunteers over 40 years at 42 locations in Switzerland. We used a case-crossover sampling design to match leaf-out dates with control dates (i.e., dates before or after leaf-out), and analyzed these data with conditional logistic regression accounting for lagged temperature effects over 60 days. Multivariate meta-analyses were used to synthesize lagged temperature and elevational effects on leaf unfolding across multiple phenological stations. Temperature effects on the probability of leaf unfolding were largest at relatively short lags (i.e., within ca. 10 days) and decreased with increasing lags. Short- to mid-term effects (i.e., within ca. 10 to 20 days) were larger for late-leafing species known to be photoperiod-sensitive (beech, Norway spruce). Temperature effects increased for the broadleaved species (horse chestnut, hazel, beech) with decreasing elevation, particularly within ca. 10 to 40 days, i.e., leaf unfolding occurs more rapidly at low elevations for a given daily maximum temperature. Our novel findings provide evidence of cumulative and long-term temperature effects on leaf unfolding, whereby the efficiency of relatively high temperatures to trigger leaf-out becomes higher shortly before bud burst. These lagged associations between temperature and leaf unfolding improve our understanding of phenological responses across temperate woody species with differing ecological requirements that occur along elevational gradients.

Influence of new snow on growth and melting of sea ice

Numerical experiments were carried out using the thermodynamic model with the aim to optimize choice of parameterization of the density of fresh snow, its albedo, and thermal conductivity coefficient in order to reproduce the seasonal evolution of ice thickness in the North-Eastern part of the Sea of Azov. The simulation results were compared with each other as well as with the observations obtained at the costal station of the Southern Scientific Center of the Russian Academy of Sciences in the Taganrog Bay. It is shown that small differences in the schemes of parameterization of physical and thermal properties of snow and ice cover may result in significant scatter in the simulation results. To assess the quality of the forecasting of the seasonal course of the ice thickness, the standard deviation of the calculated ice thickness from the average value for the period of measuring ice thickness, the standard deviation, the correlation coefficient, and the verification of the forecast were determined. Based on the analysis of these parameters, the optimal configuration of the snow layer parameters is proposed, which allows adequate reproducing of the seasonal thermal dynamics of the sea ice thickness. For the conditions of winter 2010/2011 the most close values of calculated ice thickness to results of the measurements in the North-Eastern part of the Taganrog Bay were obtained by determining the dependence of the density of fresh snow on the temperature in the near-surface layer of the atmosphere by the algorithm CLASS, albedo of the snow surface - by the scheme EHAM5, and the coefficient of thermal conductivity of snow – by the formulas of N.I. Osokin or M. Janson.

Seasonal dynamics of albedo across European boreal forests: Analysis of MODIS albedo and structural metrics from airborne LiDAR

Uncertainties in estimation of albedo-related radiative forcing cause ambiguity in evaluation of net climate effects of forests and forest management. Numerous studies have reported local relations between forest structure and albedo in the boreal zone. However, more research is needed to establish these relations for geographically extensive areas, and to examine seasonal courses of albedo to understand the effects of forest structure on mean annual shortwave energy balance. Remote sensing is a viable option for accomplishing these goals, but there are many challenges related to e.g. long periods of cloud cover and low solar elevations in high latitudes. We used the new MODIS Collection 6 (MCD43A3) daily albedo product, and analyzed MODIS albedo dependence on airborne LiDAR-based forest structure in 22 study sites in Estonia, Finland, Sweden, and Russia (57°–69° N, 12°–57° E). Wall-to-wall LiDAR data allowed us to take into account the effective spatial resolution of MODIS, which notably improved correlations between albedo and forest structure. Use of the best quality backup algorithm (magnitude inversion) together with main algorithm results in the MODIS albedo product did not reduce the correlations compared to using main algorithm only. We quantified the effects of landscape-level forest structure (forest height, canopy cover, fraction of young forest) and fraction of broadleaved deciduous forest on mean annual albedo. We showed that because the forest structure-albedo relations are the strongest in snow-covered periods, and because the snow-covered period is longest in the north, the effect of forest structure on mean annual albedo increases towards the north. On the other hand, the effect of broadleaved fraction did not show such latitudinal trend. Our results indicate that even within a single climatic zone the optimal forest management solution to mitigate climate change depends on geographic location.

Evaluation of changing weather and climate comfort conditions in Russia from 1980 to 2050

This study examined the variations in weather and climate comfort in Russia. For retrospective analysis (1980-2015), reanalysis data were used, for the future (2020-2050) were made using calculations on the climatic model of the Marchuk Institute of Numerical Mathematics RAS. The results using the data from the RCP8.5 (“hard” scenario) suggest that in areas with a strongly continental climate winters get more comfortable, but summers get less comfortable. At the same time, there is also a tendency to smooth out and almost complete absence of a seasonal course of comfort. In regions that are characterized by a temperate continental climate there is a tendency to increase comfort in winter, a decline in autumns and springs and almost no changes in the summer. In areas with oceanic type of climate, a decrease in comfort in winters is expected, as well as in autumns and springs.

Internal gravity and tidal waves in the mesopause region in Yakutia

The temperature of the mesopause region (87 km) is monitored at the Maimaga station (63.04 ° N, 129.51 ° E) using the Shamrock (Andor) spectrograph recording the hydroxyl (OH) band (3, 1). The temperature data obtained for the seasons from 2013 to 2017 are investigated. The standard deviations corresponding to the internal gravity σgw and tidal waves σtd were obtained. The seasonal course of the tidal component σtd varies from 2 to 5 K throughout all observation seasons. The seasonal variation of the gravitational component σgw observed at Maimaga station almost coincides for three observation seasons except for the 2014-2015 season. In this observation season, σgw has lower values in winter than in other seasons. Moreover, in this season average monthly temperatures exceed similar values in other seasons.

Содержание меди в органах и тканях Mytilus galloprovincialis Lamarck, 1819 и поток её седиментационного депонирования в донные осадки в хозяйствах черноморской аквакультуры

Роль мидий в формировании химического состава морской воды определяется особенностями протекания в них сорбционных и трофодинамических процессов. Медь является жизненно необходимым элементом и в то же время занимает второе место по токсичности после ртути среди десяти металлов, токсическое действие которых проверено на эмбрионах мидий и устриц. Выявление закономерностей накопления содержания меди в органах и тканях моллюсков позволяет проанализировать как санитарно-гигиенические риски их продуктового использования при выращивании в марикультуре, так и их роль в биогеохимических процессах изменения состава морской среды в акваториях размещения мидийных плантаций. Цель работы ― определить содержание ионов меди в органах и тканях мидий в масштабе сезонного хода онтогенеза, проанализировать с использованием математической модели и эмпирических данных степень их накопления моллюсками при пищевом пути минерального питания и оценить влияние марихозяйств на процессы переноса меди в прибрежной экосистеме. Моллюски отобраны с коллекторов мидийной фермы, расположенной на внешнем рейде г. Севастополя. Для определения содержания меди в системе среда ― мидии ― биоотложения использован метод атомно-абсорбционной спектроскопии с электротермической атомизацией. Представлена общая модель процесса обмена меди между мидиями и морской средой. Предложены уравнения для определения степени усвоения из пищи ионов меди (q) и предельного коэффициента их накопления (Кп) по результатам измерений концентрации в рационе мидий, в мягких тканях и в биоотложениях без применения радиоактивных меток микроэлементов. Рассчитаны величины изъятия меди из морской среды мидийной фермой. Показана роль культивируемых моллюсков в осаждении тяжёлых металлов.

Nitrogen Nutrition of European Beech Is Maintained at Sufficient Water Supply in Mixed Beech-Fir Stands

Research highlights: Interaction effects of coniferous on deciduous species have been investigated before the background of climate change. Background and objectives: The cultivation of European beech (Fagus sylvatica L.) in mixed stands has currently received attention, since the future performance of beech in mid-European forest monocultures in a changing climate is under debate. We investigated water relations and nitrogen (N) nutrition of beech in monocultures and mixed with silver-fir (Abies alba Mill.) in the Black Forest at different environmental conditions, and in the Croatian Velebit at the southern distribution limit of beech, over a seasonal course at sufficient water availability. Material and methods: Water relations were analyzed via δ13C signatures, as integrative measures of water supply assuming that photosynthesis processes were not impaired. N nutrition was characterized by N partitioning between soluble N fractions and structural N. Results: In the relatively wet year 2016, water relations of beech leaves, fir needles and roots differed by season, but generally not between beech monocultures and mixed cultivation. At all sites, previous and current year fir needles revealed significantly lower total N contents over the entire season than beech leaves. Fir fine roots exhibited higher or similar amounts of total N compared to needles. Correlation analysis revealed a strong relationship of leaf and root δ13C signatures with soil parameters at the mixed beech stands, but not at pure beech stands. While glutamine (Gln) uptake capacity of beech roots was strongly related to soil N in the monoculture beech stands, arginine (Arg) uptake capacities of beech roots were strongly related to soil N in mixed stands. Conclusions: Leaf N contents indicated a facilitative effect of silver-fir on beech on sites where soil total N concentrations where low, but an indication of competition effect where it was high. This improvement could be partially attributed to protein contents, but not to differences in uptake capacity of an individual N source. From these results it is concluded that despite similar performance of beech trees at the three field sites investigated, the association with silver-fir mediated interactive effects between species association, climate and soil parameters even at sufficient water supply.

The Water Regime of Black Saxaul in Various Environmental Conditions of the Central Asian Desert

A water regime, estimated based on transpiration rate, water content of shoots, concentration of cell sap, and water consumption per unit area, was studied for black saxaul. The seasonal course of black saxaul transpiration during the growing season increased by the middle of summer (July) and decreased towards autumn. The highest transpiration rate of black saxaul was found in Karnabchul, where ground waters poorly mineralized, located at a depth of 14–20 m in nonsaline soils. The lowest transpiration rate was detected in the Nishan “steppe,” where ground waters were also located at 14–20 m, however they were highly mineralized, and the soil profile was highly salinated. The Southwestern Kyzylkum, characterized by ground waters at a very deep location (more than 100 m) and low soil salinity, occupied an intermediate position in terms of transpiration rate. The maximal water consumption for transpiration during the vegetation period was observed in Karnabchulat 642.5 mm/ha, then in the Nishan “steppe” at 352.5. The minimal value was detected in the Southwestern Kyzylkum at 171.0.

Determining mid-day stem water potential from sap flow measurements

Trees tend to stabilize mid-day sap velocity through apparently coordinated active canopy conductance (Gc) responses to atmospheric evaporative demand. We recently reported a model describing this stabilization based on the linear relationship between canopy resistance (Rc) and vapor pressure deficit (VPD). The model was able to accurately reproduce the daily and seasonal courses of sap flow in nectarine trees for different leaf water potentials. Here, we studied inversion of the model to determine mid-day stem water potential, Ψmd, from sap flow measurements. The study was in a nectarine orchard in the hot Hula valley of northern Israel. Measurements included sap flux, weather variables, mid-day stem water potential and other parameters. Twelve trees were measured, where four were well-watered and irrigation was withheld from eight trees for eight weeks in the hot and dry summer. Ψmd declined from -1.05 to -2 MPa, and pre-dawn Ψ from -0.42 to -0.89 MPa. Similar to previous results, we found that the slope of the linear relationship between canopy resistance and VPD increased as Ψmd decreased in a monotonic manner, which was described by a linear relationship. Slopes of the relationship of canopy resistance to VPD varied linearly from 1.2 to 2.2 s mm-1 kPa-1 over the range of Ψmd values. Re-calculation of Ψmd using the relationship was very successful, giving an r2 of 0.83 between calculated and measured values.

Ground-Based Measurements of the Total Column of Freons in the Atmosphere near St. Petersburg (2009–2017)

The results of the first long-term (2009–2017) ground-based spectroscopic measurements of the total content (TC) of a number of freons in Russia are presented. According to measurements in Peterhof, TCs of CFC-11 and CFC-12 decrease at a rate of ~0.6% per year and TC of HCFC-22 grows at a rate of ~2.7% per year, which is in good agreement with independent measurements. The seasonal course of freon TC in the area of St. Petersburg is registered: highs of CFC-11 and CFC-12 are observed in summer and lows are in late winter and spring. For the HCFC-22 TC, the opposite seasonal course is observed, with a maximum in winter and a minimum in summer.

Compound-Specific Carbon Isotopes and Concentrations of Carbohydrates and Organic Acids as Indicators of Tree Decline in Mountain Pine

We investigated seasonal variations in δ13C values and concentrations of carbohydrates and organic acids in needles of declining and healthy mountain pine (Pinus mugo ssp. uncinata (DC.) Domin) trees from the Swiss National Park (SNP), using compound-specific isotopes analysis (CSIA). Our goal was to study the impact of climatic drivers on the individual compounds and understand the reasons of partial tree declines in relation to healthy mountain pine trees under seasonal weather patterns. We found that temperature is the main climatic driver determining the seasonal carbon dynamics at the needle level. Lower seasonal δ13C variability and lower concentration levels of sucrose in needles suggest less photosynthetic activity and sink carbon demand in declining compared to healthy mountain pine trees. Higher concentration levels of hexose (glucose and fructose) can play a reserve function for surviving mechanisms of mountain pine trees. Seasonal patterns of organic acid (malate and citrate) suggest an increasing investment in maintenance and repair mechanisms. The seasonal course of carbohydrates and organic acids can therefore be considered an indicator for a modified carbon metabolism within the leaves and possibly within the other tree tissues, partially explaining the decline of mountain pine trees.

Field validation of radar systems for monitoring bird migration

Abstract Advances in information technology are increasing the use of radar as a tool to investigate and monitor bird migration movements. We set up a field campaign to compare and validate outputs from different radar systems. Here we compare the pattern of nocturnal bird migration movements recorded by four different radar systems at a site in southern Sweden. Within the range of the weather radar (WR) Ängelholm, we operated a “BirdScan” (BS) dedicated bird radar, a standard marine radar (MR), and a tracking radar (TR). The measures of nightly migration intensities, provided by three of the radars (WR, BS, MR), corresponded well with respect to the relative seasonal course of migration, while absolute migration intensity agreed reasonably only between WR and BS. Flight directions derived from WR, BS and TR corresponded very well, despite very different sample sizes. Estimated mean ground speeds differed among all four systems. The correspondence among systems was highest under clear sky conditions and at high altitudes. Synthesis and applications. While different radar systems can provide useful information on nocturnal bird migration, they have distinct strengths and weaknesses, and all require supporting data to allow for species level inference. Weather radars continuously detect avian biomass flows across a wide altitude band, making them a useful tool for monitoring and predictive applications at regional to continental scales that do not rely on resolving individuals. BirdScan and marine radar’s strengths are in local and low altitude applications, such as collision risks with man‐made structures and airport safety, although marine radars should not be trusted for absolute intensities of movement. In quantifying flight behaviour of individuals, tracking radars are the most informative.

Linking stem growth respiration to the seasonal course of stem growth and GPP of Scots pine.

Current methods to study relations between stem respiration and stem growth have been hampered by problems in quantifying stem growth from dendrometer measurements, particularly on a daily time scale. This is mainly due to the water-related influences within these measurements that mask growth. A previously published model was used to remove water-related influences from measured radial stem variations to reveal a daily radial growth signal . We analysed the intra- and inter-annual relations between and estimated growth respiration rates (Rg) on a daily scale for 5 years. Results showed that Rg was weakly correlated to stem growth prior to tracheid formation, but was significant during the early summer. In the late summer, the correlation decreased slightly relative to the early summer. A 1-day time lag was found of preceding Rg. Using wavelet analysis and measurements from eddy covariance, it was found that Rg followed gross primary production and temperature with a 2 and 3 h time lag, respectively.This study shows that further in-depth analysis of in-situ growth and growth respiration dynamics is greatly needed, with a focus on cellular respiration at specific developmental stages, its woody tissue costs and linkages to source–sink processes and environmental drivers.

Characteristics of ecosystem water use efficiency in a desert riparian forest

The Ejin oasis, located on the river sides of a hyper-arid region, represents some of the richest desert ecosystems, populated with riparian forest. Water availability is the main limited factors for the distribution and growth of the forest. Currently, the water–carbon process and mechanisms in the desert riparian forest remain uncertain. The study investigated the seasonal and inter-annual variations in the gross primary productivity (GPP), evapotranspiration (ET) and ecosystem water use efficiency (WUE), and their relationships with the event (e.g., irrigation) and climatic factors. The results showed that the desert riparian forest produced new plant biomass with 0.79 g C kg−1 of water loss during the growing season. In the study period, monthly GPP and ET was tightly coupled, and the mean cumulative GPP and ET from May–October were 676 g C m−2 and 864 mm, respectively. Daily GPP and ET had similar relationships with global radiation (Rg), air temperature (Ta) and vapor pressure deficit at monthly scale. Consequently, the seasonal variations in WUE were not obvious in the growing season, except in September. In September, the value of WUE decreased significantly with an increase in Ta (for Ta > 15 °C) after irrigation, which was attributable to the increased ET and a relatively steady GPP. It is possible that the time of irrigation is able to affect the seasonal course of WUE. The study has implications that enable more rational water management to maintain the the health and activities of the riparian forest in such a hyper-arid region.

Towards pairing plot and field scale measurements in managed ecosystems: Using eddy covariance to cross-validate CO2 fluxes modeled from manual chamber campaigns

Manual chamber campaigns are a versatile method to study management effects at plot scale in factorial experiments. The eddy covariance technique has the advantage of continuous measurements but it requires large homogeneous areas. By pairing the two techniques, the uncertainties of the CO2 fluxes modeled from the chamber campaigns can be quantified through cross-validation with the continuous eddy covariance data. This is particularly important in managed ecosystems with high temporal dynamics. At our agricultural site in Northern Germany, we installed both techniques in parallel for two crop cultivation periods, winter oilseed rape in 2012/13 and winter wheat in 2013/14. First, we compared measured net CO2 exchange (NEE) obtained from the closed chambers with the corresponding half-hourly fluxes from the eddy covariance technique. Despite largely different footprints and measurement windows, the measured fluxes were highly correlated (R2 = 0.83 in 2012/13 und R2 = 0.93 in 2013/14).Interpolating from chamber campaigns to the entire measurement period is commonly performed by modeling half-hourly fluxes based on non-linear regressions for photosynthesis and respiration. These modeled fluxes were compared to the fluxes measured with the eddy covariance technique. To understand the observed differences, we performed five modeling setups: 1) Non-linear regressions based algorithm with default settings, 2) non-linear regressions with expert settings, 3) purely empirical modeling with artificial neural networks, 4) cross-validation using eddy covariance measurements as campaign fluxes on original campaign days, and 5) cross-validation on weekly campaign days.The modeled seasonal course of daily NEE agreed well with the eddy covariance measurements for all five setups (R2 from 0.77 to 0.92) but with periods of systematic offsets in the range of ±5 g C m−2 day−1. Though the pattern of the offsets was different, all setups had comparable root mean square errors around 1.5 g C m−2 day-1 despite having opposite limitations. Cross-validation by simulating campaigns with artificial gaps from the continuous eddy dataset in setup 4) and 5) resulted in bias errors of around 0.4 g C m−2 day−1. This translates to a total uncertainty on annual NEE of around ±175 g C m−2 a−1 purely from the modeling, i.e. the interpolation in-between campaigns. By leave-one-campaign-out scenarios, the sensitivity to single campaigns was examined. The mean effect on the annual total was higher for setup 4 (30 g C m−2) with the original number of campaigns than for setup 5 (9 g C m−2) with four times more campaigns. Furthermore, the interpolation in-between the campaigns can be improved by deriving vegetation proxies from the continuous eddy covariance measurements, such as an effective green area index (GAI) presented herein.

Water status, gas exchange and crop performance in a super high density olive orchard under deficit irrigation scheduled from leaf turgor measurements

We evaluated the suitability of scheduling a regulated deficit irrigation strategy in a hedgerow olive orchard with high plant density from leaf turgor related measurements. Measurements were made for two consecutive years at an olive orchard with 1667 ‘Arbequina’ trees per hectare where we had two deficit irrigation treatments, 45RDICC and 45RDITP, plus a full irrigation as a control. The two 45RDI treatments consisted on applying the same regulated deficit irrigation strategy, aimed to supply a total of 45% of the irrigation needs. The 45RDICC treatment however, was scheduled with the crop coefficient approach, while the 45RDITP treatment was scheduled with an irrigation scheduling approach based on leaf turgor related measurements, first suggested by Padilla-Díaz et al. (2016, Agric. Water Manage. 164:28–37). They worked at the orchard in 2014, and made a preliminary evaluation of the irrigation scheduling approach by comparing 45RDITP versus 45RDICC in terms of irrigation dose and frequency, predawn and midday stem water potential (Ψstem), and the fruit yields of each treatment. In this work, we considered the same variables as well as maximum daily values of stomatal conductance and CO2 net assimilation, the seasonal courses of the number of internodes in current-year shoots, leaf area and oil accumulation in the fruits, and total fruit and oil yields. All those variables were monitored both in 2014 and 2015, and we found no differences between the 45RDITP and the 45RDICC treatments, for any of them. The irrigation amounts applied to each treatment differed occasionally, but the total water supplies were similar to both 45RDI treatments. Our results, therefore, confirm the suitability of the irrigation scheduling approach proposed by Padilla-Díaz et al. (2016) to apply regulated deficit irrigation in commercial hedgerow olive orchards. We found additional evidence for the 15% changes on the irrigation amount recommended by the irrigation scheduling approach as being suitable for the orchard conditions. Caution must be taken when applying this approach to other olive orchards, since the relations between the tree water status and the shape of the daily curves recorded with the ZIM probes may depend on the cultivar and orchard conditions.

Kala-azar in Darfur: Evidence for indigenous transmission in Al-Malha Locality, North Darfur, western Sudan

BackgroundRecent reports showed high numbers of visceral leishmaniasis cases in North Darfur, western Sudan. Due to a lack of previous studies, no information is available on local transmission of the disease in these areas. Therefore, a pilot entomological and epidemiological study was conducted in Al-Malha Locality during the year 2013, to investigate possibility of local transmission and places and times of the year where and when people contract the infection.MethodsKala-azar incidence data were obtained from records of Ministry of Health, North Darfur; Al-Malha rural hospital; and the Federal Ministry of Health, Division of Communicable and Non-communicable Diseases. Sand flies were collected using sticky paper and rodent burrow traps from five different microhabitats during three different phases of the year. Species identification was undertaken using appropriate taxonomic keys. Data were statistically analyzed to determine the distribution of kala-azar among different age groups and between sexes, and to compare the species richness and distribution of different sandfly species between the different microhabitats.ResultsThe most affected age groups with kala-azar during the period 2013–2016 were children between one and five years old and those under one year. Females were found to be more affected than males. A total of 918 sand fly specimens were collected using sticky paper and rodent burrow traps from five microhabitats. Identified specimens belong to 13 species; 5 Phlebotomus and 8 Sergentomyia. Phlebotomus orientalis, the principal vector of visceral leishmaniasis (VL) in Sudan and other East African countries, was found for the first time in the area. No other known vector of VL was found in the collection. The highest number of sand flies was recorded during the summer season (63%), with S. antennata (48%) and S. schwetzi (24.1%) being the most abundant species. Among Phlebotomus species, P. orientalis showed relatively high density (8.6%). A dry seasonal water course (called “Khor”) seems to be the most preferred habitat for most of the sand fly species since most of the collections (41.2%) were made from this site, followed by the rodent burrows.ConclusionsThe presence of P. orientalis and the high prevalence of VL in infants in the Al-Malha area provide the first evidence for local transmission of the parasite causing kala-azar in Darfur. Transmission is probably occurring during summer near the woodland where a high density of the vector was recorded. As a pre-requisite for designing effective control of VL in North Darfur, large scale entomological and epidemiological studies are recommended.

Ecophysiological response of native and exotic salt marsh vegetation to waterlogging and salinity: Implications for the effects of sea-level rise

The ecophysiological characteristics of native Phragmites australis and exotic Spartina alterniflora grown under waterlogging and salinity were investigated to explore their adaptation potential to sea level rise. The seasonal course of phenotypic traits, photosynthetic activity and chlorophyll fluorescence parameters of P. australis did not change remarkably under shallow flooding, whereas these variables were sensitive to increasing salinity. Waterlogging exacerbated the negative effects of salinity on shoot growth and photosynthetic activity of P. australis, and the combined stresses led to an absence of tassel and reproductive organs. By contrast, S. alterniflora performed well under both stresses and showed an obvious adaptation of salt secretion with increasing salinity. Light salinity was the optimal condition for S. alterniflora, and the tassel growth, chlorophyll content and fluorescence characters under moderate stresses did not differ notably. The Na+ and Cl− concentrations in leaves of both species increased, and the K+ content decreased in response to salinity. Under moderate and high saline levels, the ion concentrations in S. alterniflora were maintained at relatively consistent levels with increased salt secretion. We expect the degradation of P. australis and further colonization of S. alterniflora under prolonged flooding and saltwater intrusion from sea level rise on the coastline of China.

CONTEMPORARY DYNAMICS OF COMPLEX BIOCLIMATIC INDICES DURING RESORT SEASON ON CRIMEAN PENINSULA

Contemporary dynamics of complex bioclimatic indices has been studied. Initial data was based on time series of few meteorological parameters for resort season (May - September) obtained as a result of daily monitoring on 19 Crimean stations during 2006-2014. For estimation of meteorological factors impact on human body radiative equivalent effective temperature (REET) and heat index (HI) were chosen. Dynamics of REET repetition (%) distribution by grades has shown, that on the whole peninsula territory number of cases of grade "less than comfort zone" was declining. Such dynamics is due to climatic changes manifested in air temperature growth. Grades "comfort zone" and "more than comfort zone" ate characterized by Crimean territory splitting on east and west zones with mixed tendencies. Grade "more than comfort zone" repetition for west part of peninsula is declining, and for east one - is increasing. Most favorable conditions for heliotherapy of patients with different forms of cardiovascular system diseases are evolving in resort period beginning - during May and June. Use of Steadman method for heat index evaluation allowed to estimate spatial-temporal distribution of this characteristics over Crimean peninsula territory. Formation of repetition (%) maximum of heat index in 4 p. m. in Crimea central part has been shown. In coastal zone the softening impact of Black sea is seen. In seasonal course repetition maximum of heat index is shifted to September. Distribution of heat index values by grades has shown, that the majority of cases (to 90 %) accounts grade 32-41 °C; all others - grade 41-54 °C. Dynamics of steady shifting of repetition to grade 32-41 °C was revealed.