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Context. Enhanced-efficiency nitrogen (N) fertilisers (EEFs) can reduce N loss, but productivity and environmental benefits vary. A field experiment on rainfed ryegrass dominant pastures in southern Australia examined the effect of EEFs combined with reduced N rate on agronomic N efficiency (AE) (additional biomass per unit N applied) and apparent NUE (ApNUE) (additional plant N uptake per unit N applied) relative to urea. Methods. EEFs examined were granular urea coated with (i) urease inhibitor N-(n-butyl)thiophosphoric triamide (NBPT), (ii) nitrification inhibitor 3,4-dimethylpyrazole phosphate (DMPP) or (iii) polymer coating (PCU). Nitrogen was applied five times over 9 months at 0-84 kg N [ha.sup.-1] per application. Key results. AE varied with season from -0.5 to 22.3 kg DM kg [N.sup.-1] in late (dry conditions) and early spring (ideal conditions), respectively. AE of PCU was significantly lower than urea for the first harvest due to slow N release. Using DMPP led to higher AE than equivalent urea rates in August (at 34 and 50 kg N [ha.sup.-1]) and early October (34 kg N [ha.sup.-1]). At the lowest rate (17 kg N [ha.sup.-1]), NBPT generally led to higher AE than at higher N rates. Using NBPT at 17 kg N [ha.sup.-1] led to higher AE than urea at the same rate in July, August and February. The ApNUE ranged from 3.6% (summer) to 68% (early spring), and decreased with increasing N rate. Using DMPP did not significantly change cumulative ApNUE (entire experiment) (34%) due to limited leaching and denitrifying conditions. Cumulative ApNUE was lowest with PCU (23%) due to initial slow N release. Conclusion. Seasonal variations in pasture responses to fertiliser N affected the efficiency outcomes from using EEFs. Implications. Benefits in ApNUE and AE from using EEFs rely on their seasonal strategic use combined with reduced N inputs. The initial slow release of N from the PCU could be overcome by strategies such as combining the PCU with uncoated urea, to improve ApNUE. Keywords: agronomic efficiency, DMPP, NBPT, nitrogen use efficiency, nitrification inhibitor, pasture productivity, polymer coated fertiliser, urease inhibitor., Introduction High annual nitrogen (N) rates, typically applied as urea fertiliser, are commonly used in Australian dairy pasture systems to ensure viability of the industry, with multiple applications of fertiliser [...]

This study assesses whether secondary calcification is driven by a contrasting seasonal pattern (rainy vs dry) that occurs in the Eastern Tropical Pacific (ETP). Secondary calcifiers net calcification rates and coverage were measured in two reefs: the semi-enclosed Bahía Tiburón reef (BT [21°52'30 'N, 105°54/54 'W]) and the open Las Monas fringing reef (LM [21°51E00EEN, 105°52E45EEW]). Measurements were made from 2013 to 2016 using Calcification Accretion Units (CAUs). Seawater temperature, illuminance, pCO.sub.2, pH, â¦Ca, and â¦Ar were also measured. Low means of pCO.sub.2, and high means of â¦Ca and â¦Ar, were measured during the rainy season. At Las Monas, the composition of the calcifier community differed between seasons. A seasonal effect on net calcification was recorded in the semi-enclosed reef and in the exposed microhabitat of both reefs. Overall, net calcification (mean ± SD) was 1.17 ± 1.13 g·CaCO.sub.3·m.sup.-2·day.sup.-1. Calcification in the open fringing reef (1.51 ± 1.32 g·CaCO.sub.3·m.sup.-2·day.sup.-1) was almost double that in the semi-enclosed reef (0.83 ± 0.78 g·CaCO.sub.3·m.sup.-2·day.sup.-1). Calcification also decreased dramatically between 2014 (1.57 g·CaCO.sub.3·m.sup.-2·day.sup.-1) and 2016 (0.99 g·CaCO.sub.3·m.sup.-2·day.sup.-1). The ENSO event of 2015 raised the water temperature almost 1 °C above the decadal average, which led to a mass coral bleaching in both reefs. That thermal stress might explain the calcification decline in 2015-2016, but probably also obscured a clearer seasonal pattern in net calcification. This study is the first to show that anomalous and persistent high seawater temperatures can affect carbonate production by secondary calcifiers., Author(s): Jessica M. Orrante-Alcaraz [sup.1] [sup.2] , José Luis Carballo [sup.2] [sup.3] , Benjamín Yáñez [sup.2] Author Affiliations: (1) grid.9486.3, 0000 0001 2159 0001, Posgrado en Ciencias del Mar y [...]

Climate change is receiving mounting attentions from various fields and phenology is a commonly used indicator signaling vegetation responses to climate change. Previous phenology studies have mostly focused on vegetation greening-up and its climatic driving factors, while autumn phenology has been barely touched upon. In this study, vegetation phenological metrics were extracted from MODIS NDVI data and their temporal and spatial patterns were explored on the Tibetan Plateau (TP). The results showed that the start of season (SOS) has significantly earlier trend in the first decade, while the end of season (EOS) has slightly (not significant) earlier trend. In the spatial dimension, similar patterns were also identified. The SOS plays a more significant role in regulating vegetation growing season length than EOS does. The EOS and driving effects from each factor exhibited spatially heterogeneous patterns. Biological factor is the dominant factor regulating the spatial pattern of EOS, while climate factors control its inter-annual variation. [ABSTRACT FROM AUTHOR]

Southeastern Brazil is the most populated and economically developed region of this country. Its climate consists of two distinct seasons: the dry season, extending from April to September, the precipitation is significantly reduced in comparison to that of the wet season, which extends from October to March. However, during nine days of the 2016 dry season, successive convective systems were associated with atypical precipitation events, tornadoes and at least one microburst over the southern part of this region. These events led to flooding, damages to buildings, shortages of electricity and water in several places, many injuries, and two documented deaths. The present study investigates the synoptic and dynamical features related to these anomalous events. The convective systems were embedded in an unstable environment with intense low-level jet flow and strong wind shear and were supported by a sequence of extratropical cyclones occurring over the Southwest Atlantic Ocean. These features were intensified by the Madden–Julian oscillation (MJO) in its phase 8 and by intense negative values of the Pacific South America (PSA) 2 mode. [ABSTRACT FROM AUTHOR]

After deposition of airborne basidiospores, the root disease pathogen Heterobasidion irregulare Garbelotto and Otrosina infects fresh conifer stumps and spreads through root grafts or by root contact to adjacent trees. Infection can be prevented, however, by borate application. Because the need for stump protection depends on inoculum availability, spore trapping was conducted (usually biweekly) from September 2009 through December 2011 in three infested plantations of predominantly red pine (Pinus resinosa Aiton) in central Wisconsin. A semiselective medium in Petri plates was exposed for 1 h in daylight at each of four locations in each plantation. After 7-10 days incubation at 20°C, plates were examined and presence and abundance of colonies of the Spiniger asexual stage were recorded. Heterobasidion irregulare was detected on most dates during the two growing seasons, but colonies were most abundant during late summer, fall, and early winter. Relatively fewer colonies developed on medium exposed during periods of coldest winter temperatures, but colonies of the pathogen did develop frequently on medium exposed at ≤ 5°C and occasionally on medium exposed at ≤ 0°C. Biologically based guidelines for stump treatment require additional studies of seasonal factors influencing inoculum availability, in situ spore germination, infection, and establishment of the pathogen. Key words: Heterobasidion irregulare, inoculum, Pinus resinosa. Apres le depot des basidiospores disseminees par le vent, le champignon pathogene Heterobasidion irregulare Garbelotto 6 Otrosina, responsable d'une maladie de racines, infecte les souches de conifere fraichement coupees et se propage vers les arbres adjacents par les greffes de racines et les contacts entre les racines. Il est cependant possible de prevenir l'infection par l'application de borate. Parce que la necessite de proteger les souches depend de la disponibilite de l'inoculum, les spores ont ete piegees (habituellement sur une base bihebdomadaire) du mois de septembre 2009 jusqu'en decembre 2011 dans trois plantations infectees composees surtout de pin rouge (Pinus resinosa Aiton) dans le centre du Wisconsin. Des plats de Petri contenant un milieu de culture semiselectif ont ete exposes pendant une heure durant le jour a quatre endroits dans chaque plantation. Apres 7 a 10 j d'incubation a 20°C, les plats ont ete examines et la presence ainsi que l'abondance des colonies de l'anamorphe Spiniger ont ete notees. Heterobasidion a ete detecte a la plupart des dates durant les deux saisons de croissance mais les colonies etaient plus abondantes a la fin de l'ete, en automne et au debut de l'hiver. Relativement moins de colonies se sont developpees dans les plats exposes lors des periodes hivernales les plus froides mais des colonies du pathogene se sont frequemment developpees dans les plats exposes a ≤ 5°C et occasionnellement a ≤ 0°C. D'autres etudes des facteurs saisonniers qui influencent la disponibilite de l'inoculum, la germination in situ des spores, l'infection et l'etablissement du pathogene seront necessaries pour elaborer des directives fondees sur la biologie concernant le traitement des souches. [Traduit par la Redaction] Mots-cles: Heterobasidion irregulare, inoculum, Pinus resinosa., Introduction The fungal pathogen Heterobasidion irregulare Garbelotto and Otrosina is a recently described species in the former H. annosum sensu lato species complex (Otrosina and Garbelotto 2010). Although reported hosts [...]

Abstract--We provide an overall description of the species composition and abundance of pelagic fish assemblages sampled with midwater trawls at depths ********** The dramatic increase of human activities in coastal [...]

Phase analyses of the annual cycle of monthly temperature time series that date back to the eighteenth century show trending behavior that has been difficult to interpret. Negative trends in the estimated phase have been identified with precession of Earth's axis of rotation, but the implied later onset of seasons is at odds with recent satellite measurements and with the phenological record. Positive trends in the phase and the occurrence of trends of both signs in temperature time series from geographically nearby locations have remained mysterious. This paper shows that there is a mathematical equivalence between trends in phases and seasonally differing warming trends, in particular more intense warming in winters than in summers. Using temperature time series from 16 Northern Hemispheric locations reaching back to the eighteenth century and a statistical model that can estimate the seasonal warming trends, the authors reject the hypothesis that the timing of the seasons in these locations is jointly driven by precession. [ABSTRACT FROM AUTHOR]

In the present study pedigree records maintained at Cattle Cross Breeding Project, VNMKV, Parbhani (Maharashtra) for the period of 1995-2010 were utilized to study correlation of lactation length and climatic factors. The climatic parameters considered were temperature, relative humidity, wind velocity, sunshine hours and dry and wet bulb temperature along with THI. The data on monthly lactation length of cows calved during cold, hot, south-west monsoon and post monsoon seasons were considered. Correlation and multiple regression analysis was used to investigate various sources of variation in monthly lactation length. Monthly lactation length data were analyzed to ascertain the effect of climatic attributes and to know their association with lactation lengths. The average monthly lactation length was recorded as 220.21 ± 6.75 days in Deoni cattle. It can be inferred that maximum lactation length was recorded during post monsoon season (240.94 ± 11.26 days) followed by south-west monsoon season (222.28 ± 9.00 days), cold season (218.67 ± 8.25 days) and hot season (198.95 ± 10.71 days), respectivel. [ABSTRACT FROM AUTHOR]

Hydrogen and oxygen isotopes in precipitation have been widely used as effective traces to investigate hydrological processes such as evaporation and atmospheric moisture source. This study analyzed δD and δO of precipitation in continuous event-based samples at three stations of Pailugou Catchment from November 2012 to December 2013. The δO and δD values ranged from −32.32‰ to +3.23‰ and from −254.46‰ to +12.11‰, respectively. Results show that the δO displayed a distinct seasonal variation, with enriched values occurring in summer and relatively depleted values in winter, respectively. There was a statistically significant positive correlation between the δO and δD values and local surface air temperature at all the three stations. The nearest Global Network of Isotopes in Precipitation (GNIP) station (Zhangye), compared to the Meteoric Water Lines for this study, showed the obvious local evaporation effects with lower intercept and slope. Additionally, d-excess (δD − 8δO) parameter in precipitation exhibited an anti-phase seasonal variability with the δO. The 96-h back trajectories for each precipitation event using Hybrid Single Particle Lagrangian Integrated Trajectory (HYSPLIT) model indicated a dominant effect of westerly air masses in summer and the integrated influence of westerly and polar air masses in winter. [ABSTRACT FROM AUTHOR]

The aim of this study is to detect variability and changes in the occurrence of the thermal seasons in Poland during the period from 1951 to 2010. A monthly temperature dataset using average area values allowed the researchers to set proper occurrence dates for the thermal seasons' beginnings and length according to the following criteria: winter ( t < 0 °C), early spring (0-5 °C), spring (5-15 °C), summer ( t > 15 °C), autumn (5-15 °C) and early winter (0-5 °C). Statistically significant long-term trends have been detected for the occurrence dates of the thermal seasons' beginnings and season length. Seasonal variability accelerated significantly since the end of the twentieth century. The trend of limiting wintertime in Poland is 0.64 days per year, while summer and early spring seasons are longer by approximately 0.30 and 0.25 days per year, respectively. All seasons since thermal early spring until thermal summer tend to occur earlier, while the following seasons have the opposite trend. As a result, the number of years without thermal winter has substantially increased in the past 20 years. Simultaneously, thermal summer became the longest season in 85 % of years after 1990 in comparison to less than 50 % in the period from 1951 to 1970. Also, the change in the annual course of monthly mean temperature results in the fact that thermal spring is becoming longer than thermal autumn. [ABSTRACT FROM AUTHOR]

Artificial ponds are important foraging and drinking resources for bats at La Michilía, a temperate forest with a marked seasonal drought. Using acoustic data we tested the hypothesis that water availability restricts bat activity in the dry season to ponds, whereas in the rainy season resources are widely available and therefore used throughout the area. We compared bat activity at six ponds with that of a 500-meter transect perpendicular to each pond. We predicted that activity would be higher at ponds in the dry season, whereas in the rainy season activity should be equal or higher at transects. Also, all species guilds would use ponds in the dry season, whereas gleaners, edge aerial and open aerial foragers would be more frequent at transects in the rainy season. In no instance activity was higher at transects than at ponds during the rainy season. Open areas showed little or no bat activity in the dry season, but were very active in the rainy season. One transect located in dense forest and one near human dwellings were active both seasons. Open aerial foragers were present mostly on ponds in the dry season, and on ponds and transects in the rainy season; edge aerial bats were common in ponds in the dry season, but rare in transects in the rainy season. Trawling bats used ponds and transects in both seasons; and gleaners were rare over ponds and transects in both seasons. Because bats use the local habitat differently depending on season and feeding guild, and climate and seasonality vary greatly in Mexican temperate forests, conservation strategies can not be generalized, but should be implemented on a case-by-case basis. [ABSTRACT FROM AUTHOR]

The seasonality of sunlight and rainfall regulates net primary production in tropical forests (1). Previous studies have suggested that light is more limiting than water for tropical forest productivity (2), consistent with greening of Amazon forests during the dry season in satellite data (3-7). We evaluated four potential mechanisms for the seasonal green-up phenomenon, including increases in leaf area (5-7) or leaf reflectance (3,4,6), using a sophisticated radiative transfer model (8) and independent satellite observations from lidar and optical sensors. Here we show that the apparent green up of Amazon forests in optical remote sensing data resulted from seasonal changes in near-infrared reflectance, an artefact of variations in sun-sensor geometry. Correcting this bidirectional reflectance effect eliminated seasonal changes in surface reflectance, consistent with independent lidar observations and model simulations with unchanging canopy properties. The stability of Amazon forest structure and reflectance over seasonal timescales challenges the paradigm of light-limited net primary production in Amazon forests and enhanced forest growth during drought conditions. Correcting optical remote sensing data for artefacts of sun-sensor geometry is essential to isolate the response of global vegetation to seasonal and interannual climate variability., The role of Amazon forests in the global carbon budget remains uncertain (9-12). Efforts to better constrain net carbon emissions from Amazonia have focused on the magnitude of deforestation carbon [...]

Stand transpiration ( E) estimated using the sap flux methods is affected by the azimuthal, radial, and tree-to-tree variations of sap flux. Although several studies have examined the relative importance of the three variations in estimating E, the seasonality of the three variations remains unknown. In the current study, we attempted to clarify whether the relative importance of these three variations could show seasonal changes. Using sap flux data measured in a subtropical cloud forest from August 2010 to July 2011, we calculated the differences resulting from omitting the three variations in estimating E. The effects of the three variations in estimating E showed seasonality. The azimuthal and tree-to-tree variations were more pronounced during winter, whereas the radial variation was more pronounced during summer. However, the effect of tree-to-tree variation was consistently much larger than the other two variations throughout the study period. The tree-to-tree variation is more important in estimating E monthly, seasonally and annually than both the azimuthal and radial variations, although all three variations have shown seasonality. In addition, the sensor allocation for summer would be acceptable for the practical estimation of E if aiming at the long time scale. [ABSTRACT FROM AUTHOR]

Loggers and other natural-resource-dependent workers are impacted by variable environmental conditions. This research shares logger perceptions of the impacts of seasonal environmental factors on their operations, which are important for informing forest management and policy. We conducted in-depth interviews with 17 professional loggers and 15 other forestry stakeholders to assess the challenges faced in forest operations in Wisconsin and Michigan’s Upper Peninsula. We analyzed interviews and documents to create one representative seasonal calendar, which shows the multiple, overlapping factors affecting timber operations. Many loggers identified impacts from seasonal variability and restrictions related to transportation, environmental conditions, and recreation. Seasonal environmental challenges are intertwined with and inseparable from economic challenges. Spring break-up used to be the time for rest, but increasingly, loggers do not stop working because of financial pressures to continue logging. Understanding the seasonal dynamics of timber operations can inform forest policies and climate change adaptation strategies. [ABSTRACT FROM PUBLISHER]

It is important to accurately determine the response of spring and autumn phenology to climate change in forest ecosystems, as phenological variations affect carbon balance, forest productivity, and biodiversity. We observed phenology intensively throughout spring and autumn in a temperate deciduous woodlot at Milwaukee, WI, USA, during 2007-2012. Twenty-four phenophase levels in spring and eight in autumn were recorded for 106 trees, including white ash, basswood, white oak, boxelder, red oak, and hophornbeam. Our phenological progression models revealed that accumulated degree-days and day length explained 87.9-93.4 % of the variation in spring canopy development and 75.8-89.1 % of the variation in autumn senescence. In addition, the timing of community-level spring and autumn phenophases and the length of the growing season from 1871 to 2012 were reconstructed with the models developed. All simulated spring phenophases significantly advanced at a rate from 0.24 to 0.48 days/decade ( p ≤ 0.001) during the 1871-2012 period and from 1.58 to 2.00 days/decade ( p < 0.02) during the 1970-2012 period; two simulated autumn phenophases were significantly delayed at a rate of 0.37 (mid-leaf coloration) and 0.50 (full-leaf coloration) days/decade ( p < 0.01) during the 1970-2012 period. Consequently, the simulated growing season lengthened at a rate of 0.45 and 2.50 days/decade ( p < =0.001), respectively, during the two periods. Our results further showed the variability of responses to climate between early and late spring phenophases, as well as between leaf coloration and leaf fall, and suggested accelerating simulated ecosystem responses to climate warming over the last four decades in comparison to the past 142 years. [ABSTRACT FROM AUTHOR]

Recent variations in the warm seasonal mean of surface specific humidity ( q) in Japan were studied using 34 years of data (1976-2009) from 150 meteorological observation stations of the Japan Meteorological Agency. The regional trend in the warm seasonal mean q at 3 local standard time (LST) (UTC + 9 h), averaged over Japan, increased significantly with small changes in the relative humidity: the rate of increase was +1.93 g/kg per 100 years. The warm seasonal mean q over Japan, calculated using four-times-daily data, increased slightly: the rate of increase was +0.95 g/kg per 100 years. About 16 % of the stations exhibited a significant increasing trend in warm seasonal mean q calculated using four-times-daily data; these stations were concentrated in eastern Japan. The increasing trends at 40 % of the stations were more evident for the mean q at 3 LST than at other local times. The local time at which the diurnal cycle of the mean q reached a maximum was 15 LST in period 1 (1976-1992) and tended to be delayed until up to 21 LST in the interior in period 2 (1993-2009). In addition, the rate of increase in mean q at nighttime was larger around the coastal and mountainous areas on days with well-developed thermally induced local circulation. [ABSTRACT FROM AUTHOR]

In Mediterranean seas and coastal zones, rivers can be the main source of mercury (Hg). Catchment management therefore affects the load of Hg reaching the sea with surface runoff. The major freshwater inflows to the Baltic Sea consist of large rivers. However, their systems are complex and identification of factors affecting the outflow of Hg from its catchments is difficult. For this reason, a study into the impact of watershed land use and season on mercury biogeochemistry and transport in rivers was performed along two small rivers which may be considered typical of the southern Baltic region. Neither of these rivers are currently impacted by industrial effluents, thus allowing assessment of the influence of catchment terrain and season on Hg geochemistry. The study was performed between June 2008 and May 2009 at 13 sampling points situated at different terrain types within the catchments (forest, wetland, agriculture and urban). Hg analyses were conducted by CVAFS. Arable land erosion was found to be an important source of Hg to the aquatic system, similar to urban areas. Furthermore, inflows of untreated storm water discharge resulted in a fivefold increase of Hg concentration in the rivers. The highest Hg concentration in the urban runoff was observed with the greatest amount of precipitation during summer. Moderate rainfalls enhance the inflow of bioavailable dissolved mercury into water bodies. Despite the lack of industrial effluents entering the rivers directly, the sub-catchments with anthropogenic land use were important sources of Hg in the rivers. This was caused by elution of metal, deposited in soils over the past decades, into the rivers. The obtained results are especially important in the light of recent environmental conscience regulations, enforcing the decrease of pollution by Baltic countries. [ABSTRACT FROM AUTHOR]

Variations in extreme daily temperatures are explored in relation to changes in seasonal mean temperature using 1218 high-quality U.S. temperature stations spanning 1900-2012. Extreme temperatures are amplified (or damped) by as much as ±50% relative to changes in average temperature, depending on region, season, and whether daily minimum or maximum temperature is analyzed. The majority of this regional structure in amplification is shown to follow from regional variations in temperature distributions. More specifically, there exists a close relationship between departures from normality and the degree to which extreme changes are amplified relative to the mean. To distinguish between intraseasonal and interannual contributions to nonnormality and amplification, an additional procedure, referred to as z bootstrapping, is introduced that controls for changes in the mean and variance between years. Application of z bootstrapping indicates that amplification of winter extreme variations is generally consistent with nonnormal intraseasonal variability. Summer variability, in contrast, shows interannual variations in the spread of the temperature distribution related to changes in the mean, especially in the Midwest. Changes in midwestern temperature variability are qualitatively consistent with those expected from decreases in evapotranspiration and are strongly correlated with a measure of drought intensity. The identified patterns of interannual variations in means and extremes may serve as an analog for modes of variability that can be expected at longer time scales. [ABSTRACT FROM AUTHOR]

We investigated the distribution, photoproduction, microbial uptake, and air-sea exchange of carbon monoxide (CO), a key photoproduct of chromophoric dissolved organic matter (CDOM), in open waters of the southeastern Beaufort Sea in autumn 2003 and spring 2004. Diurnal cycles of surface water CO concentration ([CO]) occurred in autumn but not in spring. In both seasons [CO] was well above air-equilibrium at most stations (maximum of 12,500% saturation) and dropped with depth to undetectable levels below 50 m. Mean surface water [CO] and CO water-column burdens (0-50 m) were 0.45 nmol [L.sup.-1] and 5.0 [micro]mol [m.sup.-2] in autumn and 4.7 nmol [L.sup.-1] and 64.8 [micro]mol m 2 in spring, and the sea-to-air CO flux was 33 times higher in spring. The efficiency of CO photoproduction correlated linearly with CDOM across the Mackenzie River estuary, the Mackenzie Shelf, and the Amundsen Gulf. Modeled water-column CO photoproduction in spring was 15 times that in autumn (45.8 vs. 3.0/[micro]mol m 2 [d.sup.-1]). Microbial CO uptake followed first-order kinetics in autumn while Hill-type, saturation, and inhibition kinetics were common in surface waters in spring. Bio-oxidation was the dominant CO loss term in autumn while gas exchange was almost equally important in spring. Higher photoproduction and slower bio-uptake in spring resulted in the wide autumn spring differences in the [CO] distribution pattern and air-sea CO flux. CO cycling in cold northern waters differs both quantitatively and qualitatively from that in warmer seas.

The study site located in the northwestern Mediterranean Sea was visited nine times in 2005-2006 to collect water samples from the epipelagic (5 m), mesopelagic (200 m, 600 m), and bathypelagic (1000 m, 2000 m) zones. The relative abundance of Bacteria, Crenarchaea, and Euryarchaea was determined by catalyzed reporter deposition fluorescence in situ hybridization (CARD-FISH). Apparent richness (total number of phylotypes detected) and community composition (different phylotypes detected) of Bacteria and Archaea were assessed by denaturing gradient gel electrophoresis (DGGE) analysis of polymerase chain reaction (PCR)-amplified fragments of the 16S ribosomal ribonucleic acid (rRNA) gene followed by sequencing and phylogenetic analysis of selected phylotypes. The relative abundance of Crenarchaea and Euryarchaea in the epipelagic zone increased as stratification decreased. Apparent bacterial richness increased with decreasing stratification in the mesopelagic and bathypelagic zones. Deep vertical mixing at the study site represented the beginning of a seasonal succession. The effects of this succession were detectable throughout the water column and led to distinct prokaryotic communities in different depth layers during the stratified period. The seasonal variability in the relative abundance of Bacteria, as well as apparent prokaryotic richness and community composition, was comparable between the different depth layers. This suggests that prokaryotic communities of the dark ocean can be as dynamic as those found at the surface.

This paper investigates the formation mechanisms for a local wind phenomenon known as Washoe Zephyr that occurs frequently in the lee of the Sierra Nevada. Unlike the typical thermally driven slope flows with upslope wind during daytime and downslope at night, the Washoe Zephyr winds blow down the lee slopes of the Sierra Nevada in the afternoon against the local pressure gradient. Long-term hourly surface wind data from several stations on the eastern slope of the Sierra Nevada and rawinsonde sounding data in the region are analyzed and numerical simulations are performed to test the suggested hypotheses on the formation mechanisms for this interesting phenomenon. The results from surface and upper-air climate data analyses and numerical modeling indicate that the Washoe Zephyr is primarily a result of a regional-scale pressure gradient that develops because of asymmetric heating of the atmosphere between the western side of the Sierra Nevada and the elevated, semiarid central Nevada and Great Basin on the eastern side of the Sierra Nevada. The frequent influence of the Pacific high on California in the summer season helps to enhance this pressure gradient and therefore strengthen the flow. Westerly synoptic-scale winds over the Sierra Nevada and the associated downward momentum transfer are not necessary for its development, but strong westerly winds aloft work in concert with the regional-scale pressure gradient to produce the strongest Washoe Zephyr events.

The present study investigated the impacts of autumn Arctic sea ice concentration (SIC) changes on the East Asian winter monsoon (EAWM) and associated climate and circulation on the interannual time scale. It is found that the Arctic SIC anomalies have little impact on the southern mode of EAWM, but the northern mode is significantly associated with both western and eastern Arctic SIC anomalies. When there is less (more) SIC in eastern (western) Arctic, the EAWM tends to be stronger. The concurrent surface air temperature anomalies are induced both locally due to the direct effect of ice cover and in remote regions through anomalous wind advection. Analysis showed that eastern Arctic SIC anomalies have a larger effect on local atmospheric stability of the lower troposphere than western Arctic SIC anomalies. Winter temperature over the midlatitudes of East Asia is lower when there is more (less) SIC in the western (eastern) Arctic. The atmospheric response to the Arctic SIC anomalies is dominantly barotropic in autumn, and changes to baroclinic over the midlatitudes of Asia, but remains barotropic in other regions in winter. The mid- to high-latitude circulation systems, including the Siberian high, the East Asian trough, and the East Asian westerly jet stream, play important roles in connecting autumn Arctic SIC anomalies and the northern mode of the EAWM variability. No obvious concurrent sea surface temperature anomalies accompany Arctic SIC variations on the interannual time scale, indicating that the Arctic SIC anomalies have independent impacts on the East Asian winter climate. [ABSTRACT FROM AUTHOR]

Direct demographical information from different populations of species in concern may reveal processes to target by management. We estimated seasonal survival rates using data from 253 individual females in a continuous population of black grouse Tetrao tetrix in Central Finland in 2005-2007. The information theoretic model selection included the effects of age class, ecological season, year, and their relevant interactions. We showed a clear difference in the survival of young and older females during late winter, a decrease in female survival during spring, and variation between the study years. The most frequent proximate mortality cause was avian predation, and the avian predation rate was highest in spring. [ABSTRACT FROM AUTHOR]

Byline: E. Klopper (1), C. H. Vogel (2), W. A. Landman (1) Abstract: The importance of anchoring seasonal climate forecasts to user needs is examined in this paper. Although it is generally accepted that seasonal climate forecasts have potential value, many constraints preclude the optimal use of these forecasts, including the way forecasts are produced, interpreted and applied in a variety of decision-making processes. In South Africa, a variety of agricultural users exists, ranging from the small-scale farmer to larger commercial farming entities. Useful seasonal are those produced and disseminated with the end user in mind. A retroactive test period during the 1990s, evaluates the perceived impact of incorporating seasonal rainfall forecasts into decisions made by commercial crop farmers in the central parts of South Africa. Although a small sample of commercial farmers was interviewed, the results show some benefits to commercial agriculture if seasonal climate forecast information is continuously and effectively applied over the long-term. Author Affiliation: (1) University of Pretoria, Pretoria, South Africa (2) University of the Witwatersrand, Johannesburg, South Africa Article History: Registration Date: 11/10/2005 Received Date: 11/03/2005 Accepted Date: 07/09/2005 Online Date: 29/03/2006

Strong typhoons in the western Pacific Ocean funnel water vapour east -- with effects on Asia's populous island nations. Strong typhoons in the western Pacific Ocean funnel water vapour east -- with effects on Asia's populous island nations., Author Affiliations: Paddles replace pedestrians in Manila. Typhoons, known for dumping torrents of rain, can help to kick-start the dry season in the Philippines and nearby nations. Credit: Ted Aljibe/AFP/Getty [...]

We report the results of a systematic long-term study of infiltration rate (IR) in a large scale effluent recharge plant, showing a significant dependence of the infiltration rate on temperature (T). Water level and T were continuously monitored and recorded in several infiltration basins of an operating wastewater treatment plant (WWTP) during the course of a 4-yr study of basin geochemistry and performance. Infiltration rates were calculated from the slope of linear plots of water level vs. time during the drainage phase. Systematic interseasonal variations of IR were observed and were strongly correlated to water T. Calculations showed that the variation of IR with T was generally 1.5 to 2.5 times larger than that predicted from effluent viscosity changes per se, suggesting the possible involvement of other T-dependent factors. This may have profound effects on the overall efficacy of wastewater reclamation and other water-recharge operations.

We conducted a study to determine the seasonal relationship between iron, sulfur, and phosphorus in the upper sediments and pore waters of a shallow intercoastal bay. From April 1999 to September 2000, sediment cores were collected from Rehoboth Bay, Delaware. Analyses of the sediments in the upper 4 cm revealed that redox conditions controlled Fe-S-P concentrations in the sediments, pore waters, and overlying water. Monthly sampling showed a marked decrease in the reactive solid phase P pool (ascorbate leachable fraction, ASC-P) and sharp increases in soluble P (measured as P[O.sup.3 -.sub.4]) in pore waters and overlying waters, as the conditions became more reducing throughout the summer months. These changes were paralleled by decreases in the amorphous Fe(III) (ascorbate leachable fraction, ASC-Fe) and total Fe(III)oxyhydroxide pools [dithionite extracted fraction, Fe[(III).sub.oxide]] and increases in solid FeS/Fe[S.sub.2]. The release of soluble P from sulfidic sediments to oxygenated overlying waters only occurred during periods of solid FeS/Fe[S.sub.2] production, which indicates that Fe(III) oxides act as a barrier to diffusive P flux. During these anoxic conditions, the regenerative P appears to induce secondary benthic algal blooms and promotes eutrophication in these inland bays through late summer. By the late fall and into early spring, sulfide production diminished and oxic conditions were reestablished as indicated by increases in solid amorphous and crystalline Fe(III) oxides and decreases in FeS/Fe[S.sub.2] concentrations. During this period, increasing ASC-Fe concentrations correlated with increases in ASC-P concentrations and decreases in pore-water P[O.sup.3-.sub.4]. The seasonal correlations between Fe-S-P indicate that Fe redox chemistry controls sediment P flux to the overlying water column.

Most ecological experiments test constant environmental conditions instead of the temporally varying conditions that are typical of most ecological systems. This study experimentally evaluated the effects of temporal variations of soil salinity and moisture on the germination of an 11-species annual plant assemblage. In soil-based microcosms with common seed banks, constant conditions were compared to different amplitudes, durations, and seasonal timing of low salinity or high moisture that simulate conditions in the upper intertidal marsh of southern California during periods of germination, The percentage germination of seeds of eight species decreased when low salinity or high moisture lasted for 1 wk before changing to high salinity and low moisture for 3 wk (varying conditions) compared to 4 wk of low salinity or high moisture (constant conditions). The seed germination speed of two species differed (both faster and slower) between the varying and constant treatments. Species responses to varying vs. constant conditions depended on the specific amplitude of temporary low salinity (0, 8, or 17 g/kg) in the varying treatments. Similarly, the duration (1, 2, or 4 wk) of low salinity or high moisture affected the percentage germination (four species) and germination speed (two species). Percentage germination (four species) and germination speed (eight species) also differed according to whether low salinity and high moisture were initiated in November, January, or March. The sensitivity of species seeds to temporally varying conditions could be explained by their germination traits and identity as native or exotic. Seeds of the six exotic species were less sensitive to varying conditions, germinated faster, and were more tolerant of high salinity and low moisture than seeds of the five native species. Varying conditions resulted in different patterns of germination than constant conditions, and environmental factors typically vary through time in the field. Thus, experimenters who are trying to understand or predict plant establishment should consider and simulate, as closely as possible, the variability in field conditions. Key words: amplitude; duration; exotics; moisture; natives; salinity; salt marsh annuals; seasonal timing; temporal variation.

Seasonal differences in the longwave radiation balance, diurnal cycles of humidity and cloudiness, and ambient winds during the warm season were evaluated to determine their effect on the nocturnal cooling processes of a high mountain hollow in central Japan. This hollow is located at an elevation of 2230 m at the bottom, having a depth of 50-200 m with a diameter of approximately 1 km. One of the most marked seasonal changes in the atmosphere is a reduction in the downward longwave radiation from summer to autumn due to reduced water vapor. This reduction is larger than that of the upward longwave radiation due to a reduced surface temperature. This radiation balance resulted in larger (smaller) potential intensity of radiative cooling during autumn (summer). A composite analysis of diurnal variation for days in summer and autumn showed that the humidity and cloud conditions, differing between the seasons, determined the initial timing and development of nocturnal cooling. During summer (July and August), increased downward longwave radiation in the evening caused by a combination of increased water vapor and cloud cover over the mountains, suppresses and delays cooling. In contrast, dry and fair weather conditions throughout early autumn (September and October) causes strong and continuous cooling. Despite the high potential for radiative cooling during late autumn (after mid-October), nocturnal cooling was frequently disturbed by strong ambient winds exceeding 3.6 m [s.sup.-1]. The weak winds during summer and early autumn have a minor effect in determining the actual cooling intensity.

In an attempt to understand the dynamics of the intertropical convergence zone (ITCZ), this study explores the extent to which the ITCZ is causally related to zonally propagating synoptic-scale disturbances. The ITCZ, measured by its mean convection, is represented by mean outgoing longwave radiation (OLR). Synoptic-scale disturbances, measured by their deep convective signals, are represented by the spectral power of the OLR that is significantly above its red-noise background. Time-mean spatial distributions as well as annual and interannual variability of the ITCZ are compared with those of synoptic-scale disturbances, which are dominated by westward-propagating signals. In general, they match each other well in their mean distributions and annual cycles. But, in detail, discrepancies between the two fields exist, some of them substantial. The maximum disturbance activity tends to be located at the polar side of the ITCZ. The seasonal cycles of the two share many similarities, but the variations in the intensity and latitudinal locations of the disturbances are greater than those of the ITCZ. On interannual timescales, their relationship is even more limited. Comparisons are also made between the observations and theories relating the ITCZ and westward-propagating synoptic-scale disturbances. The results suggest that the observed ITCZ does not owe its existence to zonally propagating synoptic-scale disturbances, in the sense that it would still exist in the absence of the disturbances. But the similarities in their means and annual cycles imply that the disturbances alone can result in an ITCZ resembling the observed one in many respects. The observations, on the other hand, are consistent with the theories that view the dynamical instability of the ITCZ as a cause of some westward-propagating synoptic-scale disturbances.

Seasonal variations in the Southern Hemisphere (SH) storm track characteristics and associated wave propagation are studied using 19 years of NCEP--NCAR gridded data. It is found that the SH storm track is strongest in the austral autumn season and weakest in spring. The characteristics of wave packets are studied by computing 1-point lag correlation maps with unfiltered meridional wind at 300 hPa. It is found that the eastward group velocities of waves are much higher than the phase velocities in the transition seasons. This shows that the downstream development occurs throughout the year and is a basic feature of upper-tropospheric waves in the midlatitudes of the SH. This extends previous studies made for winter and summer seasons. Based on the indices that show wave coherence and correlation maps, it is found that the pathways in the transition seasons split into two branches east of Australia, in a way similar to what happens in the zonal wind distribution.

Seasonal changes of uptake of nitrogenous nutrients (N[H.sup.+.sub.4], N[O.sup.-.sub.3], N[O.sup.-.sub.2], and urea) and regeneration (N[H.sup.+.sub.4] and N[O.sup.-.sub.2] production) in the plankton fraction of a mangrove ecosystem on the west coast of India were investigated. Nitrate was the major fraction of assimilable N (72%), followed by N[H.sup.+.sub.4] (16%), N[O.sup.-.sub.2] (6%), and urea (6%). Changes of nutrient concentrations followed clear seasonal cycles and were mainly regulated by in situ biological processes. The plankton took up N[O.sup.-.sub.3] and N[H.sup.+.sub.4] in more or less equal proportions (39 and 44% respectively), followed by urea (11%) and N[O.sup.-.sub.2] (6%). Seasonal patterns of uptake were distinct, with a dominance of N[O.sup.-.sub.3] and N[O.sup.-.sub.2] uptake in the postmonsoon, followed by a dominance of N[H.sup.+.sub.4] and urea uptake in the premonsoon. The high and prolonged use of N[O.sup.-.sub.3] at the beginning of the productive season was due to a strong allochthonous supply of N[O.sup.-.sub.3], dominance of microplankton, and low N[H.sup.+.sub.4] regeneration rates. Heterotrophs may take up all four nutrients and could account for half of the annual total N uptake. Ammonium and N[O.sup.-.sub.2] regeneration rates were among the highest known from nearshore waters and showed clear seasonal patterns. Production and use of N[H.sup.+.sub.4] were closely coupled. Nitrite production rates were related to N[H.sup.+.sub.4] production rates in a rectangular-hyperbolic fit. Nitrogen balance analyses showed that proximity to mangrove vegetation enhanced the flux rates, noninclusion of nitrification may lead to an overestimation of new production by 30%, and regeneration in the plankton fraction provided about 40% more N than was assimilated.

Global temperature is increasing, especially over northern lands (>50° N), owing to positive feedbacks. As this increase is most pronounced in winter, temperature seasonality (ST)-conventionally defined as the difference between summer and winter temperatures-is diminishing over time, a phenomenon that is analogous to its equatorward decline at an annual scale. The initiation, termination and performance of vegetation photosynthetic activity are tied to threshold temperatures. Trends in the timing of these thresholds and cumulative temperatures above them may alter vegetation productivity, or modify vegetation seasonality (SV), over time. The relationship between ST and SV is critically examined here with newly improved ground and satellite data sets. The observed diminishment of ST and SV is equivalent to 4° and 7° (5° and 6°) latitudinal shift equatorward during the past 30 years in the Arctic (boreal) region. Analysis of simulations from 17 state-of-the-art climate models indicates an additional STdiminishment equivalent to a 20° equatorward shift could occur this century. How SV will change in response to such large projected ST declines and the impact this will have on ecosystem services are not well understood. Hence the need for continued monitoring of northern lands as their seasonal temperature profiles evolve to resemble thosefurther south. [ABSTRACT FROM AUTHOR]

The vast majority of variability in the instrumental surface temperature record is at annual frequencies. Systematic changes in the yearly Fourier component of surface temperature have been observed since the midtwentieth century, including a shift toward earlier seasonal transitions over land. Here it is shown that the variability in the amplitude and phase of the annual cycle of surface temperature in the northern extratropics is related to Northern Hemisphere atmospheric circulation as represented by the northern annular mode (NAM) and the Pacific-North America mode (PNA). The phase of the seasonal cycle is most strongly influenced by changes in spring atmospheric circulation, whereas amplitude is most strongly influenced by winter circulation. A statistical model is developed based on the NAM and PNA values in these seasons and it successfully predicts the interdecadal trends in the seasonal cycle using parameters diagnosed only at interannual time scales. In particular, 70% of the observed amplitude trends and 68% of the observed phase trends are predicted over land, and the residual trends are consistent with internal variability. The strong relationship between atmospheric circulation and the structure of the seasonal cycle indicates that physical explanations for changes in atmospheric circulation also extend to explaining changes in the structure of the seasonal cycle. [ABSTRACT FROM AUTHOR]

Species' distribution models are widely used in landscape ecology but usually lack explicit information about species' responses to ecosystem dynamics, leading to uncertainty when applied to the prediction of seasonal change in distributions. In this study, we aimed to build a species' distribution model for the Common Quail Coturnix coturnix, a farmland species that shows changes in its distribution in response to seasonal changes in habitat suitability. During the course of three breeding seasons we collected temporal replicates of presence-absence data in 13 sampling locations in four countries ( Morocco, Portugal, Spain and France). We used generalized linear mixed models to relate the species' presence or absence to environmental variables and to the normalized difference vegetation index at each sampling location through the seasons, the latter variable being an indicator of within- and between-season habitat changes. The preferred model showed that occurrence was highly dependent on habitat changes associated with crop seasonality, as measured by the normalized difference vegetation index. Common Quail selected areas with dense vegetation and warm climate and tracked spatial changes in these two parameters. The model allows accurate mapping of within- and between-season distribution changes. Such changes are related to habitat variations caused mainly by drought and agricultural practices. Our results demonstrate that seasonal changes in farmland ecosystems can be incorporated into a simple distribution model, and our approach could be applied to other species to predict the effects of agricultural changes on the distribution of birds inhabiting farmland landscapes. [ABSTRACT FROM AUTHOR]

Export of organic matter from the surface to deeper waters often shows much smaller seasonal variations than primary production or nitrate-based new production in mid- to high-latitude marine systems. The mechanisms underlying this pattern remain poorly understood, but seasonal shifts in food web structure and dynamics have been implicated. We report here on an ecosystem modeling analysis of a high-resolution (biweekly) time series of biomass, production, and export flux (sediment trap) measurements conducted in 1991 in Bonne Bay (Newfoundland). This time series shows the classical pattern of a spring bloom followed by a summer low biomass period, yet export is bimodal, with maxima during spring and late summer. The ecosystem model was forced by diagnostic vertical mixing calculations based on temperature and salinity records taken every 3 d and hourly wind data. The physical analysis indicated that the nitrate flux into the euphotic zone during summer was equivalent to that during the spring and fall seasons and accounted for half of the summer export. Statistical adjustments of the parameters of the ecosystem model indicated that strong production of dissolved organic carbon during the spring bloom, high temperature dependence of microbial activity, and physico-chemical particle aggregation played key roles in explaining the remainder of the summer export. Seasonal changes in trophic pathways between spring and summer, such as a shift from a herbivorous to a microbial food web, played a comparatively smaller role. Our modeling analysis suggests that physical mixing processes and physico-chemical aggregation processes are at least as important as shifts in food web trophic pathways in explaining the postbloom export flux in mid- to high-latitude marine systems.

The tropical butterfly Bicyclus anynana has been studied to look at the extent to which sensitivity to temperature is affected by selection. The species shows adaptive phenotypic plasticity in response to wet-dry seasonality.