Northwestern Sites Research Articles

Root overlap and allocation of above- and belowground growth of European beech in pure and mixed stands of Douglas fir and Norway spruce

Site conditions and species identity have a combined effect on fine root growth of trees in pure and mixed stands. However, mechanisms that may contribute to this effect are rarely studied, even though they are essential to assess the potential of species to cope with climate change. This study examined fine root overlap and the linkage between fine root and stem growth of European beech (Fagus sylvatica) growing in pure and mixed stands with Douglas fir (Pseudotsuga menziesii) or Norway spruce (Picea abies) at two different study sites in northwestern Germany.The study sites represented substantially different soil and climate conditions. At each site, three stands, and at each stand, three pairs of trees were studied. In the pure beech stand, the pairs consisted of two beech trees, while in the mixed stands each pair was composed of a beech tree and a conifer. Between each pair, three evenly spaced soil cores were taken monthly throughout the growing season. In the pure beech stands, microsatellite markers were used to assign the fine roots to individual trees. Changes in stem diameter of beech were quantified and then upscaled to aboveground wood productivity with automatic high-resolution circumference dendrometers.We found that fine root overlap between neighboring trees varied independently of the distance between the paired trees or the stand types (pure versus mixed stands), indicating that there was no territorial competition. Aboveground wood productivity (wood NPP) and fine root productivity (root NPP) showed similar unimodal seasonal patterns, peaking in June. However, this pattern was more distinct for root NPP, and root NPP started earlier and lasted longer than wood NPP. The influence of site conditions on the variation in wood and root NPP of beech was stronger than that of stand type. Wood NPP was, as expected, higher at the richer site than at the poorer site. In contrast, root NPP was higher at the poorer than at the richer site.We concluded that beech can respond to limited resources not only above- but also belowground and that the negative relationship between above- and belowground growth across the study sites suggests an ‘optimal partitioning’ of growth under stress.

Spatio-temporal joint modelling on moderate and extreme air pollution in Spain

Very unhealthy air quality is consistently connected with numerous diseases. Appropriate extreme analysis and accurate predictions are in rising demand for exploring potential linked causes and for providing suggestions for the environmental agency in public policy strategy. This paper aims to model the spatial and temporal pattern of both moderate and extremely poor PM10\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$_{10}$$\\end{document} concentrations (of daily mean) collected from 342 representative monitors distributed throughout mainland Spain from 2017 to 2021. We first propose and compare a series of Bayesian hierarchical generalized extreme models of annual maxima PM10\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$_{10}$$\\end{document} concentrations, including both the fixed effect of altitude, temperature, precipitation, vapour pressure and population density, as well as the spatio-temporal random effect with the Stochastic Partial Differential Equation (SPDE) approach and a lag-one dynamic auto-regressive component (AR(1)). Under WAIC, DIC and other criteria, the best model is selected with good predictive ability based on the first four-year data (2017–2020) for training and the last-year data (2021) for testing. We bring the structure of the best model to establish the joint Bayesian model of annual mean and annual maxima PM10\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$_{10}$$\\end{document} concentrations and provide evidence that certain predictors (precipitation, vapour pressure and population density) influence comparably while the other predictors (altitude and temperature) impact reversely in the different scaled PM10\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$_{10}$$\\end{document} concentrations. The findings are applied to identify the hot-spot regions with poor air quality using excursion functions specified at the grid level. It suggests that the community of Madrid and some sites in northwestern and southern Spain are likely to be exposed to severe air pollution, simultaneously exceeding the warning risk threshold.

New Absolute Chronological Constraints to La Playa (Sonoran Desert) Archaeology between the American Southwest and Mesoamerica—From Long Period Human Resilience to Apparent Abandonment

Sonoran Desert archaeological settlement is one of the most representative sites in Northwestern Mexico/Southwestern United States of the Early Agriculture period because of various cultural processes involved, such as the introduction of the first cultigens and the construction of Pit Houses. These early desert village settlements used geomorphological features of the local landscape to facilitate their sophisticated form of agriculture. Most of the features and artifacts at the site are associated with the Early Agricultural period of 3150-1900 cal B.P., while most occupation dates are in the Cienega phase (2800-1900 cal B.P.). Later stages are poorly documented because of the apparent reduction in population, less marked archaeological features, and extreme erosion processes. Systematic archaeological excavation revealed evidence of completely burned Pit Houses. We analyzed 56 samples belonging to four Pit Houses and one different combustion feature (Kiln or Horno, as they are locally known) in different areas of the settlement. The experimental procedure included continuous susceptibility vs. temperature measurements and step-wise alternating field demagnetizations. Only 36 samples yielded technically acceptable determinations that allowed the determination of archaeomagnetic directions. Statistically indistinguishable results were obtained from all five studied features. This finding reinforces archaeological evidence of ritual-related paraphernalia and/or apparent abandonment or, at least, migration.

Understanding the transport networks complex between South Asia, Southeast Asia and China during the late Neolithic and Bronze Age

The emergence and intensification of transcontinental exchange during both the Late Neolithic and Bronze Age profoundly influenced the social history of Eurasia. While scholars have intensively discussed east-west long-distance communication along the proto-Silk Road, the north-south transport networks that connected China to South and Southeast Asia during the Late Neolithic and Bronze Age have attracted much less attention in the scholarly literature based on archeological science data. In this paper, we find new radiocarbon dates from 11 Neolithic and Bronze Age sites in northwestern and central Yunnan in Southwest China, a key entrance into South and Southeast Asia from China. Combined with previously published archeological records and radiocarbon dates, we attempt to disentangle and understand the timing and routes of the networks linking China to South and Southeast Asia during the Late Neolithic and Bronze Age. We propose three north-south land routes that played essential roles in the cultural exchanges in addition to the proto-Silk Road and maritime routes. This includes the trans-Himalayan routes, trans-Hengduan Mountain routes, and the trans-Yunnan–Guizhou Plateau routes. The north-south exchange between China and South and Southeast Asia probably emerged in the fifth millennium BP (before the present) mainly through a low-frequency trans-Yunnan–Guizhou Plateau and trans-Himalayan routes. The exchange frequency significantly increased after the fourth millennium BP, with the synchronous development of the three primary north-south passageways. Trans-Hengduan routes might have been the most crucial artery connecting China and South and Southeast Asia during 3000–2200 BP, but more archeological records are needed to understand the detailed evolution of these transport networks.

Rice’s whales in the northwestern Gulf of Mexico: call variation and occurrence beyond the known core habitat

The endangered Rice’s whaleBalaenoptera ricei, with fewer than 100 individuals remaining, is the only year-round resident baleen whale found in the Gulf of Mexico (GOM) and occurs primarily along the northeastern shelf break near De Soto Canyon. Historical whaling records and predictive density modeling suggest that these whales potentially could occur more broadly throughout the GOM. High levels of anthropogenic activities in the GOM, including oil and gas exploration and extraction, fisheries, shipping, and the unprecedentedDeepwater Horizonoil spill, highlight the need to better understand the distribution, ecology, and threats to this small population to improve protection of these endangered whales. We used long-term passive acoustic recordings from the northwestern GOM shelf break to explore the extent of Rice’s whale distribution in the northern GOM and to evaluate whether they exhibit seasonal movements throughout this range. We describe 6 new stereotyped variants of Rice’s whale long-moan calls, found predominantly in the western GOM, that share distinctive features with typical eastern long-moans, including a 150 Hz starting tone, an approximately 100 Hz tail with amplitude modulation, and a long call duration ranging from 10 to 35 s. Western long-moan variants were detected at 3 northwestern sites, occurring sporadically throughout the year on as many as 16% of days at the westernmost site, and infrequently at an eastern core-habitat site. These results indicate that some whales persistently occur over a broader range in the GOM than previously understood, which is important to consider when designating critical habitat and assessing threats to this Critically Endangered species.

Converging and diverging burn rates in North American boreal forests from the Little Ice Age to the present

Warning This article contains terms, descriptions, and opinions used for historical context that may be culturally sensitive for some readers. Background Understanding drivers of boreal forest dynamics supports adaptation strategies in the context of climate change. Aims We aimed to understand how burn rates varied since the early 1700s in North American boreal forests. Methods We used 16 fire-history study sites distributed across such forests and investigated variation in burn rates for the historical period spanning 1700–1990. These were benchmarked against recent burn rates estimated for the modern period spanning 1980–2020 using various data sources. Key results Burn rates during the historical period for most sites showed a declining trend, particularly during the early to mid 1900s. Compared to the historical period, the modern period showed less variable and lower burn rates across sites. Mean burn rates during the modern period presented divergent trends among eastern versus northwestern sites, with increasing trends in mean burn rates in most northwestern North American sites. Conclusions The synchronicity of trends suggests that large spatial patterns of atmospheric conditions drove burn rates in addition to regional changes in land use like fire exclusion and suppression. Implications Low burn rates in eastern Canadian boreal forests may continue unless climate change overrides the capacity to suppress fire.

Cadmium contents of vertically and horizontally deposited winter precipitation in Central Europe: Spatial distribution and long-term trends

Cadmium (Cd) and its forms has recently been a focus of attention due to its toxic effects on human health and the environment. We evaluated the atmospheric deposition of Cd during three consecutive winter seasons (2009–2011) at 10 mountain-top locations in the Czech Republic along the borders with Poland, Germany, Austria and Slovakia. Cadmium concentrations of soluble and insoluble forms in both horizontal (rime) and vertical (snow) deposition were determined using sector-field ICP-MS. Across the sites, 94% of the total winter Cd deposition occurred in the soluble (environmentally available) Cd form. Mean concentrations of soluble Cd in rime were six times higher than in snow (398 vs. 66 ng L−1). Vertical deposition contributed as much as 41% to the total winter Cd input. Between-site variability in Cd deposition was large, ranging between 13 and 108 μg m−2 winter−1. Overall, Cd concentrations in winter deposition did not reach the drinking water limits and did not pose a direct threat for human health. Long-term trends (1996–2017) in winter Cd deposition were evaluated at six GEOMON sites (a monitoring network of small forested catchments). Since 1996, Cd input in winter atmospheric deposition decreased by 73–93%. Simultaneously, we found declines in between-site variability in winter Cd inputs. The highest recent winter Cd inputs were found at sites located in the northeast of the country. A north-south pollution gradient, which has frequently been mentioned in the literature, was not observed, with both northwestern sites and southern sites being among those with the lowest Cd pollution. Backward trajectories of the HYSPLIT model for fresh snow samples identified Poland and Germany as major transboundary Cd pollution sources for the Czech Republic.

Beech and silver fir\u2019s response along the Balkan\u2019s latitudinal gradient

At the 1000 km geographical distance in Dinaric montane forests of silver fir (Abies alba Mill.) and European beech (Fagus sylvatica L.), the tree response from the north-western sites towards southern, warmer and dryer sites was performed during three consecutive growing seasons (2011, 2012 and 2013). On eleven permanent plots, positioned in uneven-aged beech and fir forests above 800 m along the geographical gradient, the physiological and morphological response to light intensity were measured in predefined light categories based on the analysis of hemispherical photos. Radial growth was analysed on all plots and compared to precipitation, temperature and two drought indexes. Analysis showed a decrease in the cumulative precipitation and no change in temperature between plots. Beech was most efficient in the open area light conditions, while fir proved most efficient under shelter. Physiological response for beech increased towards SE and reached its maximal values in the middle of transect, while fir’s response decreased from the NW towards SE. Tendency to plagiotropic growth decreased from NW to SE in both species. Growth response to climatic parameters is weak, stronger in fir than in beech and decreasing towards SE.

Limited fine-scale larval dispersal of the threatened brooding corals Heliopora spp. as evidenced by population genetics and numerical simulation

Coral reefs are declining worldwide due to regional and global anthropogenic stress. Sekisei Lagoon and areas in its vicinity are impacted by the same stresses. Sekisei Lagoon is the largest coral reef area in Japan covering an area of almost 15 km × 20 km. Being situated upstream of Kuroshio Current, coral reefs in this area could supply larvae to downstream such as the Ryukyu Archipelago, facilitating high biodiversity. To conserve corals in such an area, estimation of larval dispersal among populations is essential because connectivity via larval dispersal is associated with the time for replenishment after disturbance. Isolated coral populations have a higher risk of local extinction. The purpose of this study is to reveal genetically isolated populations of brooding corals with short larval durations in and around Sekisei Lagoon. For this purpose, we utilized both population genetic analysis and larval dispersal simulations. Based on genotyping of 929 colonies of blue coral, Heliopora spp., collected from 22 sites around Sekisei Lagoon, genetic analysis suggested self-recruitment with connectivity in the southeastern sites and northwestern sites. Particle-tracking larval dispersal simulations also revealed similar patterns, corroborating the genetic results. These results suggest that lagoonal scale connectivity among populations of Heliopora spp. in Sekisei Lagoon is limited, as expected based on its short larval duration. Our results highlight the fact that most of the Heliopora spp. populations are genetically isolated, even inside Sekisei Lagoon, implying that the likelihood of being replenished by larval supply from surrounding populations after a disturbance is low and have a higher risk of local extinction than other coral species with high larval dispersal potential.

Domestic and Transboundary Sources of Atmospheric Particulate Bound Mercury in Remote Areas of China: Evidence from Mercury Isotopes

Isotopic composition of atmospheric particulate bound mercury (PBM) was obtained at four remote sites in different geographical regions of China for three to 12 month periods. Mean (±1σ) Δ199HgPBM was the highest at the site in southwestern China (0.66 ± 0.32‰), followed by the site in northeastern China (0.36 ± 0.34‰), the site in the marine boundary layer of East China Sea (0.35 ± 0.33‰), and was the lowest at the site in northwestern China (0.27 ± 0.22‰). Δ199HgPBM was relatively higher in cold than warm season at the sites in northwestern and southwestern China, whereas the opposite was found at the site in northeastern China. We propose that the seasonal variations of Δ199HgPBM were influenced by the exposure of air masses to regional (e.g., anthropogenic and dust related) and long-range (e.g., anthropogenic and oceanic) sources in the preceding several days, with the former characterized by lower Δ199HgPBM and the latter characterized by more positive Δ199HgPBM due to sufficient atmospheric transformations. Modeling results from Potential Source Contribution Function suggested that domestic anthropogenic emission was the major contributor to PBM pollution at the sites in northeastern and eastern China, whereas long-range transboundary transport of PBM from South Asia played a more important role at the sites in southwestern and northwestern China.

Wound healing properties of aqueous extracts of Sargassum illicifolium: An in vitro assay

Abstract Background Seaweeds contain biologically active molecules which are important in the pharmaceutical industry. The present study was aimed to investigate the effects of aqueous extract of seaweeds:Sargassum illicifolium (S.i) on the stimulation of mouse fibroblast cell proliferation and migration. Materials and methods Sargassum illicifolium-SW12, Sargassum illicifolium-SW13, and Sargassum illicifolium-SW23 were collected from Northern, North Western and Southern coastal sites of Sri Lanka respectively. To determine the cytotoxic of S.i extracts were used the MTT assay. The scratch wound healing assay was performed using the mouse fibroblasts (L929) cells that assess the cell proliferation and migration. The highest cell proliferation of S.i species aqueous extracts was measured by observing the change in the size of the scratch wound area. Results A concentration of S.i extracts 0.954 ± 0.04 μg/μl (Mean ± SE), (P Conclusions Cell proliferation and migration were significantly faster in those treated with S.i-SW23 aqueous extracts when compared with the control group. Moreover, no cytotoxic effect of S.i aqueous extracts on L929 cell line were observed. This study suggests that S.i might be a potential therapeutic agent for skin wound healing by promoting fibroblast proliferation and migration. Further studies are highly warranted to identify active molecules in the extracts. Moreover, in-vivo studies would further verify wound healing therapeutic applications shown here.

A role for artificial night-time lighting in long-term changes in populations of 100 widespread macro-moths in UK and Ireland: a citizen-science study

The abundance of 100 of the most widespread species of macro-moth in the UK and Ireland was estimated from light-trap records reported to the UK and Ireland Garden Moth Scheme between 2005 and 2015. Recording sites were classified into low, medium and high night-time illumination categories by satellite imagery, into land-use types from the dominant use in the 1–2 km surrounding area, and by latitude. Most urban sites were in the group classified as having high night-time illumination. Comparison between medium and low night-time illuminated sites allowed differences between levels of illumination free from the effect of urbanization on moth abundance to be assessed. The medium and low night-time illuminated sites differed significantly in the frequency of grassland and arable land-use types and in geographic location with more grassland and north-western sites in the low-light category. After adjustment for these differences and for variations between taxonomic family groups, the medium to low night-time lighting abundance ratios explained a significant (P < 0.001) 20% of the variance in long-term changes in moth abundance reported by the Rothamsted Insect Survey for the years 1968–2002. This is the first demonstration that artificial night-time lighting has had, in combination with other factors, a significant influence on levels of abundance of moth populations.

Genetic diversity of Thymus sibthorpii Bentham in mountainous natural grasslands of Northern Greece as related to local factors and plant community structure

The local scale genetic diversity of Thymus sibthorbii, an aromatic species of the Greek flora, was studied both in relation to its habitat characteristics. The study was conducted in Cholomontas mountain, northern Greece at altitudes of 760–870m. Genetic material from Southern and Northwestern exposures and from different grazing intensities within each exposure, was studied using ISSR molecular markers. The plant cover at each study site was measured and the floristic composition of the site was calculated. The grazing intensity affected the species composition and reduced the abundance of T. sibthorpii. The floristic diversity in terms of species richness, evenness and Shannon index (IF) was higher at the southern sites. Within population gene diversity (HE) ranged from 0.203 to 0.245 and Shannon index (IG) from 0.311 to 0.377. Most of the genetic diversity resided within populations (88%). Significant genetic differentiation was detected among the populations from the southern and northwestern sites, as well as among populations of each exposure. Genetic diversity of T. sibthorpii was not correlated to species diversity (richness and evenness), either within or between populations. Instead, genetic diversity was found to be positively correlated with environmental factors, such as N soil content and soil moisture.

The Iberian town of Ullastret (Catalonia). An Iron Age urban agglomeration reconstructed virtually

The Iberian town of Ullastret (6th-2nd centuries BC), in the NE of the Iberian Peninsula, is one of the most important Iron Age archaeological sites in the north-western Mediterranean. It consists of two residential areas, Puig de Sant Andreu and Illa d’enReixac. Separated by only 300 m, together they make up the capital of the Iberian tribe known as the Indiketes, mentioned by classical authors such as Avienus, Ptolemy and Strabo. Decades of continuous archaeological investigation, and especially the geophysics surveys undertaken in recent years, have given us an overall view of the urban structure of this dipolis and its immediate territory, which was occupied and exploited intensively starting mainly in the 4th century BC. This high degree of theoretical knowledge led us to propose the creation of a virtual reconstruction of the whole complex, as well as its contextualisation in its geomorphologic and landscape surroundings. This 3D modelling is an excellent research tool that permits the formulation-validation of hypotheses for architectural reconstruction. It is also especially useful for the creation of applications that add to our knowledge of this heritage site and aid in its presentation and dissemination.

UNDERGROUND PITS (CHULTUNES) IN THE SOUTHERN MAYA LOWLANDS: EXCAVATION RESULTS FROM CLASSIC PERIOD MAYA SITES IN NORTHWESTERN PETÉN

AbstractChultunes— underground pits carved into bedrock — have been reported by the hundreds in the Maya region, yet debate on their principal use continues to this day. Sincechultuneshave not yielded solid data to answer the questions posed by Maya archeologists, they are sometimes not completely excavated or reported in detail. This article presents a review of previous work onchultunesin the Maya lowlands, followed by the presentation of new data from sixchultunesexcavated at archaeological sites in northwestern Petén, Guatemala. I argue that, although these underground features were primarily used for utilitarian purposes, there is strong evidence thatchultunesalso had ritual importance to the ancient Maya. The variability in the shape, size, and associated cultural materials, including macrobotanical remains, justifies further in-depth investigations ofchultunes. Archaeologists should consider investigating these features more systematically, as a larger comparative sample ofchultunescould aid in assessing whether there are local patterns of construction, use, and reuse. Thus, excavations of these features should be encouraged.

Dry deposition and canopy uptake in Mediterranean holm-oak forests estimated with a canopy budget model: A focus on N estimations

Bulk/wet and throughfall fluxes of major compounds were measured from June 2011 to June 2013 at four Mediterranean holm-oak (Quercus ilex) forests in the Iberian Peninsula. Regression analysis between net throughfall fluxes and precipitation indicated that the best defined canopy process was leaching for K+ and uptake for NH4+ at all sites. A more variable response between sites was found for Na+, Ca2+, SO42- and Cl−, which suggests that the interplay of dry deposition, leaching and uptake at the canopy was different depending on site climate and air quality characteristics.A canopy budget model (CBM) was used to try to discriminate between the canopy processes and enable to estimate dry deposition and uptake fluxes at three of the sites that complied with the model specifications. To derive N uptake, an efficiency factor of NH4+vs. NO3− uptake (xNH4) corresponding to moles of NH4+ taken up for each NO3− mol, has to be determined. Up to now, a value of 6 has been proposed for temperate forests, but we lack information for Mediterranean forests. Experimental determination of N absorption on Quercus ilex seedlings in Spain suggests efficiency factors from 1 to 6. Based on these values, a sensitivity analysis for xNH4 was performed and the NH4N and NO3N modeled dry deposition was compared with dry deposition estimated with independent methods (inferential modeling and washing of branches). At two sites in NE Spain under a milder Mediterranean climate, the best match was obtained for xNH4 = 6, corroborating results from European temperate forests. Based on this value, total DIN deposition was 12–13 kg N ha−1 y−1 at these sites. However, for a site in central Spain under drier conditions, variation of the NH4+ efficiency factor had little effect on DD estimates (which ranged from 2 to 2.6 kg N ha−1 y−1 with varying xNH4); when added to wet deposition, this produced a total N deposition in the range 2.6–3.4 kg N ha−1 y−1. Dry deposition was the predominant pathway for N, accounting for 60–80% of total deposition, while for base cations wet deposition dominated (55–65%). Nitrogen deposition values at the northwestern sites were close to the empirical critical load proposed for evergreen sclerophyllous Mediterranean forests (15–17 kg N ha−1 y−1). When organic N deposition at these forests is added (3 kg N ha−1 y−1), the total N input to the sites in NE Spain are close to the critical loads for Mediterranean evergreen oak forests.

Site‐Effects Investigation in the City of Chlef (Formerly El‐Asnam), Algeria, Using Earthquake and Ambient Vibration Data

Weak‐motion recordings of local earthquakes and ambient vibration data in the 0.2–15 Hz frequency range were used to quantify site effects in downtown Chlef city, Algeria. Nine short‐period stations were installed in the city. A total of 15 local events with 3.1≤ M L≤4.9 were selected. Three experimental techniques were applied: standard spectral ratios, receiver functions, and horizontal‐to‐vertical spectral ratios using ambient vibrations (HVSRN). Theoretical HVSRN curves were also calculated from suggested soil models for each site. Fundamental frequencies obtained from all techniques showed good agreement. Two groups of fundamental frequencies were distinguished in the city. In the northern part of the study area, the frequency peaks varied from 0.3 to 0.4 Hz; in the southern part they varied from 0.6 to 1.6 Hz. The amplification factors of these frequency peaks were 4–8. Earthquake and ambient vibration data were able to identify fundamental frequency peaks successfully; however, the amplitudes of the peaks were slightly lower for ambient vibrations. Moreover, the fundamental frequency peak progressively increased from northwest to southeast, which is consistent with the direction of decreasing thickness of a Miocene layer overlying the basement. We infer, as expected, that the large impedance contrast between Miocene deposits and Mesozoic basement, which can be interpreted as seismic bedrock, is the cause of the fundamental frequency. Furthermore, earthquake data were more appropriate for identifying peaks at frequencies higher than the fundamental one. Indeed, a clear peak was observed at all northwestern sites in the 3–4 Hz range, with an amplification factor of 3–5. At the other sites, particularly in the center of the city, the peak was less evident.

Nitrogen Fertilization Strategies Suitable to Achieve the Quality Requirements of Wheat for Biscuit Production

A low grain protein content (GPC) and flour strength (W) are desirable traits for wheat (Triticum aestivum L.) for biscuit production. Nitrogen fertilization is the main factor that affects storage proteins. The aim of this study was to compare the effect of different commonly applied N fertilization strategies on the quality requirements of common wheat intended for biscuits production. Field experiments were set up over three growing seasons at three sites in northwestern Italy on two wheat cultivars. Three N rates (100, 130, and 170 kg N ha−1), applied split as ammonium nitrate, have been compared to a slow release fertilizer, applied only at tillering (130 kg N ha−1). The leaf greenness, grain yield, grain and flour protein content, and W were affected directly by the rate of N distributed as ammonium nitrate in several of compared agro‐environments. Taking in account the same N rate, the application of a slow release fertilizer resulted in a significantly lower GPC (4%), W (6%), and flour stability measured through the Brabender farinograph (10%) compared to the split fertilization with ammonium nitrate, while no difference was observed for ear density and grain yield. Suitable rheological parameters of wheat for biscuits could be achieved through the split application of ammonium nitrate only at low N rate, but this could limit their productive performances. Conversely, the fertilization strategy of applying a slow release fertilizer at tillering is able to better satisfy the qualitative requirements for biscuit production, without causing any grain yield loss.

Chilling and Host Plant/Site-Associated Eclosion Times of Western Cherry Fruit Fly (Diptera: Tephritidae) and a Host-Specific Parasitoid.

The western cherry fruit fly, Rhagoletis indifferens Curran (Diptera: Tephritidae), is an endemic herbivore of bitter cherry, Prunus emarginata (Douglas ex Hooker) Eaton, but ∼100 years ago established on earlier-fruiting domesticated sweet cherry, Prunus avium (L.) L. Here, we determined if eclosion times of adult R. indifferens from sweet and bitter cherry differ according to the phenology of their respective host plants and if eclosion times of the host-specific parasitoid Diachasma muliebre (Muesebeck) (Hymenoptera: Braconidae) attacking bitter and sweet cherry flies differ according to the eclosion phenology of their fly hosts. Fly pupae from sweet and bitter cherry fruit were collected from sympatric and allopatric sites in Washington state, and chilled at 5°C. Because timing of eclosion in R. indifferens depends on chill duration, eclosion time in wasps could also vary with chill duration. To account for this, fly pupae were chilled for 1, 2, 2.5, 3, 4, 6, or 8 mo. Both flies and wasps eclosed earlier with longer chill durations. Eclosion times of sweet and bitter cherry flies from a sympatric site in central Washington did not differ. However, at allopatric sites in northwestern and central Washington, bitter cherry flies eclosed later than sweet and bitter cherry flies at the sympatric site. Correspondingly, D. muliebre parasitizing a more isolated bitter cherry fly population eclosed later than D. muliebre parasitizing earlier-emerging sweet and bitter cherry fly populations. These results provide evidence for D. muliebre rapidly responding to changes in host plant shifts by R. indifferens.

Improvements in statistical forecasts of monthly and two‐monthly surface air temperatures using a stratospheric predictor

Anomalies in the extratropical stratospheric circulation are known to affect climate at the surface for up to 2 months during winter. Previously, several studies have proposed simple statistical models based on a stratospheric predictor to forecast surface climate; however, none of these studies considered a possibility, nor evaluated the skill, of categorical weather forecasts at individual sites. Here we evaluate the skill of the three‐category (below‐normal, near‐normal and above‐normal) monthly and two‐monthly mean surface air temperature statistical forecasts, both deterministic and probabilistic, which use, as predictors, normalized mean polar cap geopotential height at 150 hPa and mean surface air temperature over the preceding 30‐day period (persistence). We show that, during the period 1957–2013, at several sites influenced by the Northern Annular Mode variability, the monthly and two‐monthly forecasts based on the stratospheric predictor possess a moderate skill in December–March at lead times of several days, but in many cases they only marginally improve forecasts based on persistence only. Nevertheless at some sites in northeastern Europe and northwestern Russia the improvements indicate that statistical climate forecasting at these sites can benefit from addition of stratospheric information. The results of this study further demonstrate usefulness of simple statistical models based on stratospheric predictors, both as a complementary source of forecasts, and as providing benchmarks for evaluating the skill of more complex dynamical systems.