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  • Pulkkinen, Paavo (1966)
  • Smirnova, Inna (2014)
    There is an increasing need for organizations to collaborate with internal and external partners on a global scale for creating software-based products and services. Many aspects and risks need to be addressed when setting up such global collaborations. Different types of collaborations such as engineering collaborations or innovation-focused collaborations need to be considered. Further aspects such as cultural and social aspects, coordination, infrastructure, organizational change process, and communication issues need to be examined. Although there are already experiences available with respect to setting up global collaborations, they are mainly focusing on certain specific areas. An overall holistic approach that guides companies in systematically setting up global collaborations for software-based products is widely missing. The goal of this thesis is to analyze existing literature and related information and to extract topics that need be taken into account while establishing global software development collaborations - to identify solutions, risks, success factors, strategies, good experiences as well as good examples. This information is structured in a way so that it can be used by companies as a well-grounded holistic approach to guide companies effectively in setting up long-term global collaborations in the domain “software development”. The presented approach is based on scientific findings reported in literature, driven by industry needs, and confirmed by industry experts. The content of the thesis consists of two main parts: In the first part a literature study analyzes existing experience reports, case studies and other available literature in order to identify what aspects and practices need to be considered by organizations when setting up global collaborations in the domain software development. Secondly, based on the results from the literature review and consultation with the industrial partner Daimler AG, the identified aspects and practices are structured and prioritized in the form of activity roadmaps, which present a holistic guide for setting up global collaborations. The developed guidance worksheet, the so-called “Global canvas”, is meant to be a guide and reminder of all major activities that are necessary to perform when doing global collaborations for software-based products and services. The main contributions of this thesis are an analysis of the state of the practice in setting-up of global software development collaborations, identification of aspects and successful practices that need to be addressed by organizations when doing global collaborations for software-based products and services and the creation of a holistic approach that presents scientific findings to industry in an effective and credible way and guides companies in systematically setting up global collaborations.
  • Rintala, Janne-Markus (Helsingin yliopisto, 2009)
    The seasonal occurrence of sea ice that annually covers almost half the Baltic Sea area provides a unique habitat for halo- and cold temperature-tolerant extremophiles. Baltic Sea ice biology has more than 100 years of tradition that began with the floristic observation of species by the early pioneers using light microscopic techniques that were the only thing available at the time. Since the discovery of life within sea ice, more technologies have become available for taxonomy. Electron microscopy and genetic evidence have been used to identify sea ice biota revealing increased numbers of taxa. Meanwhile ecologists have used light microscopic cell enumeration in addition to the chemical and physical properties of sea ice in attempts to explain the food web structure of sea ice and its functions. Thus, during the Baltic winter, the sea ice hosts more abundant and diverse microbial communities than the water column beneath it. These communities are typically dominated by autotrophic diatoms together with a diverse assortment of dinoflagellates, auto- and heterotrophic flagellates, ciliates, metazoan rotifers and bacteria, which are mostly responsible for the recycling of nutrients. This thesis comprises ecological and systematic studies. In addition to the results of the previous studies carried out on landfast ice, the data presented here provide new insight into the spatial distribution of pelagial sea ice, which has remained largely unexplored. The studies reveal spatial heterogeneity in the pelagial sea ice of the Gulf of Bothnia. There were mismatches in chlorophyll-a concentrations and in photosynthetic efficiencies of the communities studied. The temporal succession was followed and experimental studies performed investigating the community responses towards increased or decreased light in landfast ice in the Gulf of Finland. The systematic studies carried out with established dinoflagellate cultures revealed a new resting cyst belonging to common sea ice dinoflagellate, Scrippsiella hangoei (Schiller) Larsen 1995. The cyst can be used to explain the overwintering of this species during prolonged periods of darkness. The dissimilarities and similarities in the material isolated from the sea ice called for description of a new subspecies Heterocapsa arctica ssp. frigida. The cells obtained in the cultured material were unlike those of the previously described species, necessitating description of ssp. frigida. As a result of its own unique habitus, the subspecies had been noted by Finnish taxonomists during the past three decades and thus its annual occurrence and geographical distribution in the Baltic Sea. This illustrates how combining ecology and systematics increases our understanding of organisms.
  • Toppila, Esko (Helsingin yliopisto, 2000)
  • Lundström, Maria (University of Helsinki, 2015)
    Åtalsuppgörelse utgör ett alternativt straffprocessuellt förfarande, genom vilket den misstänkte kan få ett lindrigare straff, ifall hen erkänner och underlättar utredningen av det brott/de brott som hen misstänks för. Eftersom en fullständig förundersökning, åtalsprövning och domstolshandläggning inte behöver förrättas, sparar förfarandet betydande resurser under straffprocessens alla skeden. Frågor kring processekonomi har blivit allt viktigare i takt med att den finska statens ekonomiska situation har försämrats. Även det stora antalet fällande domar som Finland fått av Europeiska människorättsdomstolen, för att straffprocesserna tar för länge, har ökat pressen att utveckla nya mer processekonomiska förfaranden. Processekonomi utgör den främsta orsaken till att åtalsuppgörelse introducerades i lagstiftningen fr.o.m. 1.1.2015. I takt med att åtalsuppgörelse har börjat användas i Finland har det dock blivit tydligt att lagstiftningen i sin nuvarande form inte främjar en smidig tillämpning. I denna pro gradu-avhandling undersöker jag de praktiska problem som kan uppstå då åtalsuppgörelseförfarandet tillämpas. Syftet med avhandlingen är att lyfta fram de problempunkter som tydligt belastar åtalsuppgörelseförfarandet i dess nuvarande form samt presentera konkreta förbättringsförslag angående hur förfarandet borde utvecklas. Avhandlingen inleds med en rättsdogmatisk undersökning de lege lata, då jag i kapitel två och tre redogör för åtalsuppgörelseförfarandets förenlighet med viktiga principer inom straffprocessrätten samt för förfarandets utformning i lagstiftningen. I kapitel fyra konstruerar jag typfall som illustrerar en del av de problem som kan uppstå när förfarandet tillämpas. I kapitel fem och sex undersöker jag problemen närmare samt presenterar mina förbättringsförslag. Denna del av avhandlingen är en studie de lege ferenda, eftersom jag undersöker hur lagstiftningen kring åtalsuppgörelse borde utvecklas för att göra förfarandet smidigare och lättare att tillämpa. I det sjunde och sista kapitlet sammanfattar jag mina observationer och tankar kring förfarandet och dess plats i det finska rättssystemet. Mina förbättringsförslag till förfarandet kan sammanfattas enligt följande: För det första borde åklagaren ges större befogenheter att förhandla under åtalsuppgörelseförfarandet. Åklagaren borde kunna förhandla om brottets omständigheter samt om övriga yrkanden i anknytning till brottet. För det andra borde målsägandens möjlighet att hindra tillämpningen av åtalsuppgörelseförfarandet begränsas. Målsäganden borde inte kunna förbjuda tillämpningen av förfarandet och därav föreslår jag att målsägandens sekundära åtalsrätt borde begränsas ifall åtalsuppgörelseförfarandet blir tillämpligt. För det tredje borde reglerna kring ändringssökandet ses över. Jag föreslår att man borde begränsa svarandens möjlighet att återta erkännandet efter att domförslaget fastställts samt även begränsa möjligheten att söka ändring i fastställda domförslag. Tillstånd till fortsatt handläggning borde gälla för alla överklaganden av fastställda domförslag. Vidare anser jag att reglerna om överklagan borde utvecklas så att det skulle vara möjligt att söka ändring i avskrivna domförslag. I annat fall skapas ingen rättspraxis kring vilka brott som kan handläggas via åtalsuppgörelse. Som sista förbättringsförslag framför jag att man på sikt borde utvidga förfarandets tillämplighet att gälla fler brottstyper så att bl.a. misshandelsbrott och grova narkotikabrott kunde handläggas via åtalsuppgörelse.
  • Lavikainen, Antti (Helsingin yliopisto, 2014)
    The most pathogenic zoonotic cestodes of humans belong to the family Taeniidae. Members of this family (taeniids) are parasites of mammals requiring predatory definitive hosts and herbivorous or omnivorous intermediate hosts. Due to the major medical, veterinary and economic importance, taeniids have been a topic of intensive taxonomic, ecological and epidemiological studies resulting in contrasting conclusions about the diversity within the family. Currently, two genera, Echinococcus and Taenia, are widely recognized. Identification of taeniid tapeworms and their taxonomic classification have traditionally been based on morphological criteria. Development of molecular genetic techniques has provided more accurate tools for identification. The aims of the present thesis were to elucidate evolutionary relationships of taeniids, to explore the diversity within the family and to evaluate the taeniid taxonomy on the basis of phylogenetic relationships. Special emphasis was on species occurring in the Holarctic region. Parasite material collected mainly in northern Europe, a worldwide collection of taeniid DNA specimens and previously published sequence data were used in phylogenetic analyses. Molecular genetic characterization of taeniid taxa and preliminary phylogenies were based on short mitochondrial DNA (mtDNA) sequences. For further phylogenetic analyses, longer mtDNA regions, complete genes and finally mitochondrial genomes, as well as nuclear genes, were used. Based on the molecular analyses, cryptic or previously unknown species and intraspecific entities were detected, and the specific status of some taeniid taxa was confirmed. The genus Taenia was shown to be a highly diversified and paraphyletic assemblage justifying a generic level taxonomic revision. A new genus, Versteria, was created for Taenia mustelae, which was placed as a sister taxon to Echinococcus in phylogenies. An old generic name, Hydatigera, was resurrected for Taenia taeniaeformis and closely related species. The knowledge of taxonomy and evolutionary history of taeniids is essential for better understanding of the epidemiology and transmission of these parasites. The present thesis clarifies the taxonomy of the Taeniidae and creates a framework for further phylogenetic studies, possible additional revisions and comparative research.
  • Heinonen, Jussi (Helsingin yliopisto, 2015)
    Pro gradu -tutkielman aiheena on ”Ateistinen retoriikka Ilkka Pyysiäisen teoksessa Jumalaa ei ole”. Kyseinen teos toimii tutkielman lähdeaineistona. Retoriikka ymmärretään työssä laajasti siten, että se käsittää retoristen keinojen käytön lisäksi asia-argumentaation. Käytetyt menetelmät jakautuvat siten kahtaalle, toisaalta argumentaatioanalyysiin, toisaalta retoristen keinojen analyysiin. Käytettyjen menetelmien osalta argumentaatioanalyysi sisältää formaalin ja sisällöllisen aspektin: samalla kun tarkastellaan argumenttien rakennetta, päästään tutustumaan siihen teoksen sisällölliseen kontekstiin, jossa argumentaatio tapahtuu. Retoristen keinojen osalta esitellään niitä keinoja, joita teoksen kirjoittaja käyttää saavuttaakseen lukijan vakuuttamiseen tähtäävät tavoitteet. Teoksen argumentaatiota koskeva yleishavainto on, että argumenttien kirjo on melko suppea. Niiden pääasiallinen tavoite on osoittaa kristinuskon mukaiset uskomukset vääriksi vedoten moderniin tieteeseen, jonka piirissä Jumalasta ei ole tehty havaintoja ja joka ei tarvitse Jumalaa teorioidensa ja selitystensä rakenneosana tai perustana. Teoksen retoristen käyttö on sen argumentaatiota rikkaampaa, mikä sopii hyvin teoksen poleemiseen pamflettiluonteeseen. Käytetyt retoriset keinot kytkeytyvät usein toisiinsa, minkä ansiosta teksti on retorisesti tiheää. Läpikäyvänä juonteena on erityisesti komiikan käyttö retorisena keinona. Tutkielmassa tarkastellaan myös ateismin käsitettä ja historiaa erityisesti viimeaikaisen ateismikeskustelun kohdalla pyrkien sijoittamaan tarkasteltava teos ateismin kontekstiin. Läpi teoksen toistuva argumentti, jonka mukaan tiede kumoaa uskonnon, ankkuroi teoksen perusasennoitumiseltaan skientistiseksi. Skientistinen asenne yhdistää teosta viime vuosina voimakkaasti esiin nousseen uusateismin tunnetuimpien angloamerikkalaisten edustajien kirjoituksiin. Retoriikan osalta teos sijoittuu kärkevyydessä johtavien uusateistien ääripäiden välimaastoon. Viimeaikaisessa ateismin ilmiökentässä on havaittavissa myös merkitykseltään yhä kasvava ilmiö, jossa ateismi ja henkisyyden harjoittaminen pyritään yhdistämään toisiinsa. On esimerkiksi perustettu yhteisöjä, jotka lainaavat uskonnoista niiden parhaat puolet. Samalla kuitenkin pidetään kiinni ateistisesta vakaumuksesta. Pyysiäisen kirjassa ei tämäntapaista myötämielistä suhtautumista uskontoon ole, kuten ei myöskään pyrkimystä löytää yhteistä kieltä tai käydä dialogia uskonnon edustajien kanssa.
  • Lahti, Satu (Helsingin yliopisto, 2010)
    The objective of the present study was to increase knowledge about the atelier culture of recent history, especially about the ways in which atelier clothes were made. I look at the ways of dress-making in the production of a renowned atelier, Salon Kaarlo Forsman. I also give a general outline of the atelier. The studying method I used was triangulation, which is a typical approach in case studies of recent history. My data include 23 dresses by the Salon Forsman, theme interviews of four of the Salon workers and one mannequin, data from my research work, as well as press material and archives. The basis of the analysis of these materials was a theme frame that I had put together with the help of pre-understanding. I then completed and defined the theme frame on the basis of the analysis of the data. I also analyzed the dresses in the fashion photos in the press material. Salon Kaarlo Forsman represents a certain cultural period, the years 1937-1986, and a place where a woman could have individual clothes made for her, from hats to fur coats. The atelier was particularly known for embroidery with beads, draping, and fantastic cuttings designed by the owner, fashion designer Kaarlo Forsman. I draw an outline of the work and practices of the atelier, but also that of Kaarlo Forsman’s life work, as he had a great influence on the sewing methods atelier clothes. Mr. Forsman was able to stretch the first period of modern fashion well into the third period by refusing new, labor-saving methods and sticking to individually designer clothes to the end of his enterprise. The crucial practices in the atelier that I present in this study are fitting, designing, finishing and sewing, as well as beading and the decoration of dresses. I compare the activity, practices and dress-making methods in the Forsman atelier to that of Haute Couture in Paris, which served as model for Finnish fashion houses. I point out the similarities and differences.
  • Ollila, Pauli (2004)
    When making judgements of the quality of survey sampling, especially with the complex estimators, the method of variance estimation is of importance. In addition to the well-known linearisation approach, there are many methods based on the sample reuse. The variety of these methods, especially in sampling theory, does not have any unified theoretical framework. The first part of the thesis is a theoretical overview for variance estimation, covering the foundations of the sampling theory and the current methodology of variance estimation. Also new methods and theoretical results are provided in the thesis. The cumulants and k-statistics are utilised to study the theoretical correction coefficient of unbiased variance estimation. Some examples of this approach are given for the variance estimation of the estimator of the population variance. The post-design vectors, i.e. artificially expanded design vectors for variance estimation, are used as the scale adjustment needed to correct the effect of the difference between the sampling design and resampling design. There are also correction methods utilising two-phase resample spaces and alternatively two resample to introduce various estimator-dependent scale corrections. New sampling distribution results concerning without-replacement and with-replacement designs in two-phase sampling situations are presented. A variance decomposition approach utilising sample pair probabilities is given with variance estimators. Finally, both old and new methods are tested with two real small populations. Results reveal e.g. that the two-phase resample approach deminishes the bias almost for every estimator studied, and for one estimator the sample pair probability approach provides unbiased variance estimator.
  • Ollila, Pauli (2004)
    Kun tehdään johtopäätöksiä otantaan perustuvista surveytutkimuksista, erityisesti monimutkaisilla estimaattoreilla, varianssiestimointimenetelmän oikea valinta on monessa tapauksessa tärkeää. Tunnetun linearisointiin perustuvan varianssiestimointimenetelmän lisäksi on olemassa monia menetelmiä, jotka perustuvat otoksen uudiskäyttöön. Näiden menetelmien laaja kirjo, erityisesti otantateoriassa, ei omaa vielä yhtenäistä teoreettista viitekehystä. Väitöskirjan ensimmäinen osa on teoreettinen katsaus varianssiestimointiin, kattaen otantateorian perusteet sekä nykyisen varianssiestimointimetodologian. Väitöskirja esittelee myös uusia varianssiestimointimenetelmiä sekä teoreettisia tuloksia. Kumulantteja ja k-tunnuslukuja käytetään hyväksi tutkittaessa teoreettista korjauskerrointa harhattoman varianssiestimoinnin tapauksessa. Esimerkkejä tästä lähestymistavasta annetaan perusjoukon varianssin estimaattorin varianssiestimoinnissa. Jälkiasetelmavektoreita, toisin sanoen varianssiestimointia varten keinotekoisesti laajennettuja asetelmavektoreita, käytetään skaalamuunnoksessa, joka tarvitaan korjattaessa otanta-asetelman ja uusotanta-asetelman välisen eron vaikutusta varianssiestimointiin. Väitöskirja sisältää myös korjausmenetelmiä, jotka käyttävät hyväksi kaksivaiheisia uusotanta-avaruuksia ja vaihtoehtoisesti kahden uusotoskoon avaruuksia, jotta mukaan tulisi myös estimaattorista riippuva korjaustekijä. Työssä esitetään myös uusia otantajakaumatuloksia kaksivaiheisessa otannassa koskien palauttamatta- ja palauttaen-tyyppisiä otanta-asetelmia. Varianssin hajottamista termeihin koostuen yksittäisotos- ja otosparitodennäköisyyksistä käytetään hyväksi eri varianssiestimaattoreissa. Lopuksi sekä vanhoja että uusia menetelmiä testataan kahdella olemassaolevalla pienellä perusjoukolla. Tuloksista näkyy, että mm. kaksivaiheisessa uusotannassa varianssiestimaattorin harha pienenee melkein jokaisella tutkituista estimattoreista, sekä yhdelle estimaattorille otosparimenetelmä tuottaa harhattoman varianssiestimaattorin.
  • Tiilikainen, Sanna (2013)
    This study describes how the families studied use and domesticate digital entertainment technologies and services at home as a part of their practices. Data were collected using fieldwork and analyzed using grounded theory. A total of eight families with children were visited, for one weekday afternoon each. During the visits, each family member was interviewed and their use of entertainment was observed and photographed. Family members also completed some assignments. Motivations for use and relevant technological development factors found were classified into key categories, and relationships between these were recognized to form theory on family digital entertainment use at home. The theory is presented as a flowchart and a narrative. The results are integrated with sociological theories and research on domestication and practices. The results of this theoretical integration are presented as a second flowchart model and a narrative. The findings are also compared with user acceptance models from other disciplines. The research question of this study is: “How do families with children use digital entertainment at home?” The main results are that families with children use digital entertainment at home in a socially conditioned way and as a part of their everyday practices. Family members have to take others living in the same household into account when making choices. Recent developmental advances in entertainment technology (ease of use and personalization) enable new ways of using entertainment at home, encouraging the social and practical aspects of digital entertainment. Uses, places and meanings of entertainment at home are evolving. Digital entertainment technologies are becoming a part of a technology mediated lifestyle. New and traditional forms of entertainment are used side by side at home and in many creative ways. The studied families are spending quality time together in two ways: in “Traditional quality time” everybody focuses on the same entertainment and in “Personalized quality time” everybody is using their entertainment device of choice in a shared space while commenting on the content. Entertainment that fits into the practices of a family is called “part of our life” and its use is actively encouraged. Forms of entertainment that do not fit the practices of a family are rejected.
  • Jumppanen, Henna (2002)
  • Huotari, Inkeri (1991)
  • Halminen, Saskia (2015)
    I denna avhandling undersöks kvinnliga proffsidrottares reflexiva förhållande till sin kropp. Frågan om deras idrottarskap, hur de tar hand om sin kropp och vad de tänker om både sin egen och hästens kropp som idrottare är centrala frågor i behandlingen av ämnet. Den teoretiska referensramen baserar sig på Bourdieus klassiska habitusbegrepp, applicerat på idrottande kvinnor i ridsport och hur de ser på sig själva och varandra, och på Crossleys reflexiva kroppstekniker, applicerat på ryttarens kropp och hästens kropp samt deras kroppars reflexiva förhållande. Forskningsfrågan handlar om kvinnliga, manliga och idrottsliga aspekter i ridningssammanhang, och ifall det är mer accepterat att vara kvinna och toppidrottare i ridning än i andra idrottsgrenar. Ridsport är en alldeles särskild sport genom att muskler och styrka inte är det viktigaste, utan andra grenspecifika kompetenser också spelar en stor roll. Dessutom är förhållandet till hästen viktigt. Ridsport är den enda OS-grenen där män och kvinnor tävlar mot varandra på samma nivå, och en gren som kvinnor tagit till sig både som hobby och toppidrott. I stallomgivningen blandas kvinnliga och manliga sätt och attribut på ett naturligt sätt: män kan bli vårdare och visa känslor, och kvinnor kan bli tuffa och starka. Denna kvalitativa studie baserar sig på åtta halvstrutkurerade temaintervjuer med informanter av varierande nationaliteter. På basis av resultaten av denna undersökning kan man säga att ridning är en icke-problematisk idrottsgren för kvinnor. Professionella kvinnoryttare känner sig bekväma i sin kropp både på hästryggen, då de utövar sin sport, och utanför hästvärlden. De känner inte att de måste ge upp sin kvinnlighet för sitt idrottande, till skillnad från vad flera studier om till exempel ishockey-eller fotbollsspelande kvinnor visar på. Ridning visade sig vara en intressant reflexiv kroppsteknik. Hästens och ryttarens kroppar påverkar och formateras av varandras kroppar i ett ömsesidigt förhållande både i stunden och på längre sikt. Ryttarskapet är en implementerad del av proffsryttarnas identitet och påverkar deras habitus. Det tycks vara så att kvinnliga proffsryttare inte behöver välja mellan att vara atlet, hästtjej eller kvinna. Det går bra att vara all tre av dessa på samma gång eller variera mellan dessa roller enligt sitt eget tycke.
  • Vesanto, Veli-Heikki (Helsingin yliopisto, 2012)
    While spaceborne satellite data has been extensively used to extract biophysical forest characteristics through reflectance features and indices, there are still many questions regarding seasonal changes in reflectance. Boreal forests have already seen changes in growth patterns from climate change, and the large scale monitoring of these forests is becoming more important. Understanding seasonal changes in reflectance in the boreal region will allow for the monitoring of seasonal biophysical changes using satellite imagery. For this monitoring to be possible the satellite imagery needs to be preprocessed and atmospherically corrected to create a time series of hemispherical-directional reflectance factors. The red edge is the abrupt change in reflectance between 680 and 740 nm seen in vegetation spectra. The red edge inflection point is the wavelength, at which the slope is steepest in the red edge. The red edge inflection point is sensitive to plant chlorophyll content and has been extensively used for estimating vegetation biophysical parameters including: leaf-area index, biomass and plant health levels. Hyperion is a narrowband imaging spectrometer aboard the Earth Observer-1 satellite. Hyperion captures data across 242 spectral bands covering a spectral range of 356 to 2577 nm resulting in a nominal spectral range of 10 nm. While the high spectral resolution of Hyperion makes it possible to calculate the REIP, there is no consensus on how this should be done, with different methods producing conflicting results. This study explains the preprocessing and atmospheric correction of a seasonal time series of five Hyperion EO-1 images (Provided courtesy of the USGS) from Hyytiälä, Southern Finland (61° 51 N, 24° 17 E). The time series ranges from 31.5.2010 to 12.8.2010, covering much of the growing season and the seasonal changes in reflectance. The first derivative, four-point linear interpolation, Lagrangian interpolation, and fifth-order polynomial fitting methods for calculating the REIP are looked at to determine their applicability for Hyperion imagery using this time series. Hyperion data requires considerable preprocessing before atmospheric correction can be done. In this study the preprocessing covered: destriping, desmiling, atmospheric correction and finally geocorrection. Atmospheric correction was done using both FLAASH and ATCOR, both of which are MODTRAN based absolute atmospheric correction algorithms. The final atmospherically corrected HDRF images were evaluated using in situ handheld spectrometer reference measurements of a grass field in the area. An average RMSE value of around 3% was achieved with both algorithms. The corrected Hyperion images were also compared against two MODIS products, which also showed good agreement. The aerosol retrieval however did not work with either algorithm, on any scene. The use of a sun photometer for aerosol level estimation was also not effective. Due to the dynamics of the red edge and expected seasonal red edge inflection point trends, the fifth-order polynomial fitting method was seen as the best method for calculating the red edge inflection point. The red edge inflection point did not correlate strongly with leaf area index overall, however there was a strong correlation with individual plots. A strong correlation was observed between Hyperion red edge inflection point and understory red edge inflection point, both overall and for individual plots.
  • Arcaro, Anthony Matthew (University of Helsinki, 2015)
    Canopy interactions and their effects on the chemical composition of throughfall were studied in three plots within two forests of Taita Hills, Kenya over a period of one year. The two forests studied are hilltop forest fragments at the elevated peak of Vuria and northern and southern Ngangao. The stands represent lower evergreen rainforest and upper montane rain/cloud forest ecosystems, which are becoming increasingly vulnerable to degradation by human population growth in the area and the effects of climate change. The forest plots have recently been placed under government protection and the data in this study has been collected as part of the TAITAWATER project of the Academy of Finland. The objective of this thesis is to quantify and chemically analyze rainfall and throughfall in order to compare the canopy interactions occurring in the three study plots. Hemispherical photographs of the canopy were also taken to assess leaf area index. Tree mapping and species identification were also carried out. In an attempt to evaluate the influence that indigenous forests in the region have on fresh water availability and quality the amount, pH, and electrical conductivity of collected rainfall or throughfall was recorded weekly. Additionally, water samples were taken and analyzed for their chemical content (Total N, NH4-, NO3-, S, Cl, Ca, Mg, K, P, Na, Si, B) in a laboratory using ICP. In agreement with previous studies the data exhibits a few trends, which indicate that canopy interception and cloud drip result in higher throughfall amounts in cloud forests, particularly during drier parts of the year when heavy rain events are scarce. Canopy interactions can also alter the chemical composition of precipitation as it passes through the canopy towards the forest floor. The canopy interactions in Taita Hills enriched throughfall with nearly all solutes leading to significant increases in EC while maintaining lower pH. The canopy with a higher presence of bryophyte and lichen species showed a greater propensity to influence the nutrient fluxes of total nitrogen and phosphorus despite containing less biomass.