Browsing by Subject "weather"

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  • Odanga, James J.; Mohamed, Samira; Olubayo, Florence; Nyankanga, Richard; Mwalusepo, Sizah; Subramanian, Sevgan; Johansson, Tino Petri; Ekesi, Sunday (2017)
    Avocado, Persea americana Miller (Lauraceae), is an important fruit crop cultivated by small-holder farmers along Afrotropical highlands of Taita Hills in South-eastern Kenya and Mount Kilimanjaro in Northern Tanzania. The small-holder farmers in these East African regions generate substantial food and cash from avocado fruits. However, the avocado crop is faced with challenges of infestation by insect pests such as the common blossom thrips (Frankliniella schultzei Trybom) which feeds on pollen and floral tissue thereby reducing productivity of the trees. Moreover, there is no information describing distribution patterns of Frankliniella schultzei and associated weather in East African avocado orchards despite the fact that small-scale farming is dependent on rainfall. This article was, therefore, initiated to provide dataset on abundance of Frankliniella schultzei from the avocado plants that relates with monthly rainfall and air temperatures at Taita Hills and Mount Kilimanjaro. Frankliniella schultzei was collected using white coloured beating tray and camel brush whereas air temperatures (°C) and rainfall (mm) was recorded daily using automatic data loggers and rain gauge, respectively. The survey at the two transects commenced during peak flowering season of avocado crop in August up to end of harvesting period in July of the following year. Temporal datasets were generated by Kruskal-Wallis Chi-square test. Current temporal datasets presents strong baseline information specifically for Kenya and Tanzania government agencies to develop further agricultural strategies aimed at improving avocado farming within Taita Hills and Mount Kilimanjaro agro-ecosystems.
  • Ianevski, Aleksandr; Zusinaite, Eva; Shtaida, Nastassia; Kallio-Kokko, Hannimari; Valkonen, Miia; Kantele, Anu; Telling, Kaidi; Lutsar, Irja; Letjuka, Pille; Metelitsa, Natalja; Oksenych, Valentyn; Dumpis, Uga; Vitkauskiene, Astra; Stasaitis, Kestutis; Öhrmalm, Christina; Bondeson, Kåre; Bergqvist, Anders; Cox, Rebecca J.; Tenson, Tanel; Merits, Andres; Kainov, Denis E. (2019)
    With the increasing pace of global warming, it is important to understand the role of meteorological factors in influenza virus (IV) epidemics. In this study, we investigated the impact of temperature, UV index, humidity, wind speed, atmospheric pressure, and precipitation on IV activity in Norway, Sweden, Finland, Estonia, Latvia and Lithuania during 2010-2018. Both correlation and machine learning analyses revealed that low temperature and UV indexes were the most predictive meteorological factors for IV epidemics in Northern Europe. Our in vitro experiments confirmed that low temperature and UV radiation preserved IV infectivity. Associations between these meteorological factors and IV activity could improve surveillance and promote development of accurate predictive models for future influenza outbreaks in the region.
  • Rytteri, Susu; Kuussaari, Mikko; Saastamoinen, Marjo (2021)
    Climate change affects insects in several ways, including phenological shifts that may cause asynchrony between herbivore insects and their host plants. Insect larvae typically have limited movement capacity and are consequently dependent on the microhabitat conditions of their immediate surroundings. Based on intensive field monitoring over two springs and on larger-scale metapopulation-level survey over the same years, we used Bayesian spatial regression modelling to study the effects of weather and microclimatic field conditions on the development and survival of post-diapause larvae of the Glanville fritillary butterfly Melitaea cinxia on its northern range edge. Moreover, we assessed whether the observed variation in growth and survival in a spring characterized by exceptionally warm weather early in the season translated into population dynamic effects on the metapopulation scale. While similar weather conditions enhanced larval survival and growth rate in the spring, microclimatic conditions affected survival and growth contrastingly due to the phenological asynchrony between larvae and their host plants in microclimates that supported fastest growth. In the warmest microclimates, larvae reached temperatures over 20 degrees C above ambient leading to increased feeding, which was not supported by the more slowly growing host plants. At the metapopulation level, population growth rate was highest in local populations with heterogeneous microhabitats. We demonstrate how exceptionally warm weather early in the spring caused a phenological asynchrony between butterfly larvae and their host plants. Choice of warmest microhabitats for oviposition is adaptive under predominant conditions, but it may become maladaptive if early spring temperatures rise. Such conditions may lead to larvae breaking diapause earlier without equally advancing host plant growth. Microclimatic variability within and among populations is likely to have a crucial buffering effect against climate change in many insects.
  • Kostamo, K.; Toljamo, A.; Kokko, H.; Kärenlampi, S. O.; Rita, H. (2018)
    Fluctuations in the yield of wild berries are markedly influenced by weather conditions. However, the cause-effect relationship is often poorly understood. Based on data spanning a 20-year period in Finland, we made an effort to elucidate the influence of different weather conditions on the yield of arctic bramble (Rubus arcticus L). We analyzed the regression coefficients of various weather conditions in several regression models using the elaboration approach. Temperature accumulated in July had a positive effect on yield. Yield was negatively influenced by temperature accumulated during the previous summer, rainfall in the October of the previous year, and temperature accumulated in May of the same year. It is notable that the same weather conditions had a positive influence on yield of the same year whereas these conditions had a negative effect on the yield potential of the following year. Compared with traditional analysis methods, the elaboration approach provided a better understanding of the relationship between weather parameters and yield. The rarity of a good yield could be explained by the particular vulnerability of arctic bramble to the negative effects of weather conditions. Some of these factors could be controlled in field conditions when cultivating arctic bramble.
  • Sivonen, Tero (Helsingfors universitet, 2014)
    Osprey Pandion haliaetus has been under a strict surveillance of the nature conservationists and a conservation icon since the early 70’s. At that time the accumulation of persistent environmental toxins and pollutants lowered the populations of many birds of prey to low levels, threatening the survival of entire species. Nowadays osprey is one of the successful models of endangered species protection. Because of its status osprey is very thoroughly studied raptor. Due to environmental toxins many birds of prey suffered from eggshell thinning and lost clutches till the end of 1970’s. Eggshell thinning has later stopped and is now reverting, but after the start of intense studying of the birds other threats have been observed to reduce reproductive success. Many earlier studies have suggested that extreme weather conditions may have an effect on the nesting success of diurnal birds of prey. In osprey´s case many researchers have examined the effects of different weather patterns to foraging success and food delivery, but a specific review over their effects on the nesting success hasn’t been conducted so far. In this study I focus on the effects of different weather factors and their contemporary nesting success. I study a nature conservation based supplementary feeding pond‘s effect to the local osprey population’s reproductive success, combined with the weather variables and the density of nesting pairs. Osprey is recorded to fly approximately 3–15 km on its foraging trips. At their longest these fishing trips can be over 40 km long one-way. The Osprey Center, working in Pohtiolampi at Kangasala (61° 26.876' N, 24° 7.705' E), in Southern Finland, feeds the local ospreys with living rainbow trout from an old fish farm pool. In theory, the birds nesting or living near the supplementary feeding pond benefit from this in a form of easy sustenance. The fish move near the water surface and are thus available all the time. Especially during bad weather conditions the pond is frequently visited by nesting ospreys. In this study I examine 1) does supplementary feeding have an effect on the nesting success of the local osprey population, 2) what is the role of weather factors affecting the breeding success and 3) does supplementary feeding have an effect on nesting density? I used 16 years of weather and breeding data (1997–2012) and evaluated the individual and combined weather variables and their possible effects on nesting success and brood production, comparing study and control area. I set my study area in a shape of a circle with 30 km radius. Pohtiolampi feeding pond was placed in the center of the study area, surrounded by a vast labyrinthine lake area. For the control area’s and study area's ecosystems to be as much alike as possible, I established the control area, also in a form of a circle and continuing the next 30 km, to start where the study area ended (see: Map 1.). I calculated the covariance and Akaike weights of different weather variables and annual nesting success with R (2.15.0) statistical calculation program. Collinearity was assessed with variance inflation factors (VIF). Generalized linear mixed models (GLM), to asses simultaneously the role of weather variables and the nesting success of both study and control area, were used. Finally the scenarios were arranged in significance order by their AICc values (Akaike information criterion adjusted for finite sample size). After the comparing analysis, I repeated the calculations also without the division to study and control area, gaining information about the effects of weather variables in general. I also calculated the proportional effects of different land use types to the nesting density of the local osprey population by using ArcGIS mapping tool and compared the results between study and control area. My results indicate that supplementary feeding does not influence the nesting success. Same annual average of young fledged the nests each year, regardless of the area. Weather variables, however, showed some effect on the nesting success when viewing the entire population. The assembled weather data shows examples of weaker nesting success in summers with prolonged storms, rainy weather or low average temperature. However, levels of significance, derived from the data, are still too low to be used as generalizations. Only three day long storms had a better AIC weight than the null model. I presume that the good fishing waters, wind shelter and shoreline forests are possible explanations to this trend. Most harmful weather to the osprey nestlings was a prolonged storm (? 7 m/s wind) and rainy summers. The nesting density of osprey was recorded to be significantly higher in the study area than in the control area, when viewing the total land acreage. Moreover, I recorded that the density in the study area grew up to almost four times the number of control area, when studying the acreage of potential nesting areas. When viewing the area of foraging waters the difference was reduced to 1.5 fold. I conclude that the local osprey population benefits from the supplementary feeding area by nesting more densely near the abundant food source and thus producing more young per km².
  • Vansteelant, W. M. G.; Kekkonen, J.; Byholm, P. (2017)
    Contemporary tracking studies reveal that low migratory connectivity between breeding and non-breeding ranges is common in migrant landbirds. It is unclear, however, how internal factors and early-life experiences of individual migrants shape the development of their migration routes and concomitant population-level non-breeding distributions. Stochastic wind conditions and geography may determine whether and where migrants end up by the end of their journey. We tested this hypothesis by satellite-tagging 31 fledgling honey buzzards Pernis apivorus from southern Finland and used a global atmospheric reanalysis model to estimate the wind conditions they encountered on their first outbound migration. Migration routes diverged rapidly upon departure and the birds eventually spread out across 3340 km of longitude. Using linear regression models, we show that the birds' longitudinal speeds were strongly affected by zonal wind speed, and negatively affected by latitudinal wind, with significant but minor differences between individuals. Eventually, 49% of variability in the birds' total longitudinal displacements was accounted for by wind conditions on migration. Some birds circumvented the Baltic Sea via Scandinavia or engaged in unusual downwind movements over the Mediterranean, which also affected the longitude at which these individuals arrived in sub-Saharan Africa. To understand why adult migrants use the migration routes and non-breeding sites they use, we must take into account the way in which wind conditions moulded their very first journeys. Our results present some of the first evidence into the mechanisms through which low migratory connectivity emerges.