Advances in molecular methods for analyzing DNA, RNA and proteins in humans as well as in other animals, plants, fungi, bacteria or viruses have greatly increased the resolution with which we can study life’s complexity and dynamics on earth. While genomic, transcriptomic and proteomic laboratory tools for molecular diagnosis of disease are rapidly becoming more comprehensive, the access to such advanced yet often expensive and centralized procedures is limited. There is a great need for rapid and comprehensive diagnostic methods in low-resource settings or contexts where a person can not or will not go to a hospital or medical laboratory, yet where a clinical analysis is urgent. In this thesis, results from development and characterization of novel technologies for DNA and protein microarray analysis are presented. Emphasis is on methods that could provide rapid, cost-effective and portable analysis with convenient readout and retained diagnostic accuracy. The first study presents a magnetic bead-based approach for DNA microarray analysis for a rapid visual detection of single nucleotide polymorphisms. In the second work, magnetic beads were used as detection reagents for rapid differential detection of presence of pestiviral family members using a DNA oligonucleotide microarray with read-out by means of a tabletop scanner or a digital camera. In paper three, autoimmune responses from human sera were detected on a protein autoantigen microarray, again by means of magnetic bead analysis. Here, special emphasis was made in comprehensively comparing the performance of the magnetic bead detection to common fluorescence-based detection. In the fourth study, an immunochromatographic lateral flow protein microarray assay is presented for application in the classification of contagious pleuropneumonia from bovine serum samples. The analysis could be performed within 10 minutes using a table top scanner, and the performance of the assay was shown to be comparable to that of a cocktail ELISA. In the fifth paper, the lateral flow microarray framework is investigated in further detail by means of experiments and numerical simulation. It was found that downstream effects play an important role, and the results further suggest that the downstream binding profiles may find use in simple affinity evaluation. / QC 20100713

Paper-fluidic devices are a popular platform for point-of-care diagnostics due to their low cost, ease of use, and equipment-free detection of target molecules. The most common example is the lateral flow assay, in which samples are added to a paper membrane and a colorimetric indicator provides a binary signal indicating whether the molecule of interest is present. A novel lateral flow assay was developed to detect a protein biomarker for early stage cervical cancer. Cervical cancer can be cured if detected and treated at an early stage, but approximately 90% of cervical cancer deaths occur in low and middle-income countries due to lack of accessible testing. Methods for detecting the biomarker, valosin-containing protein (VCP), were optimized using enzymatic and gold nanoparticle dot blots, then lateral flow assays were developed and validated using purified VCP and cervical cancer HeLa cells. Future validation with patient tissue samples will permit translation of this device to testing clinics in low-resource areas. Despite advantages for use in resource limited settings, lateral flow assays are limited by their inability to perform more complex or multi-step processes, such as nucleic acid amplification or enzymatic signal enhancement. Thermally actuated wax valves are one mechanism that provides complete control over fluid obstruction and release. To better understand how wax valves can be used in fully automated, self-contained lateral flow assays, different sizes and geometries of valves were tested to investigate their effects on actuation time, flow rate, and flow pattern. Another limitation in the understanding of lateral flow assays is the lack of experimental data describing the microscale flow within the pores of the paper membrane that drives the biophysical reactions in the assay. Mathematical models can be designed to explain macroscopic phenomena, but so far, no literature has compared microfluidic models to microfluidic data. To quantify microfluidic properties within lateral flow assays, fluorescent nanoparticles were imaged flowing through different areas of the membrane and their velocity was quantified using micro-particle image velocimetry (µPIV). Scanning electron microscope images were used to verify that this experimental model was reasonable for describing microfluidic properties of the lateral flow assay. Altogether, this document investigates how developing lateral flow assays for cervical cancer detection can save lives by improving the accessibility of an early diagnosis, and how more robust lateral flow assay characterization can expand their applicability to a broad range of detection processes.

A low cost compact diagnostic has many implications in today’s society. Smart phone technology has exponentially grown and with it the imaging capabilities associated with smart phones. The goals of this research are i) to determine the feasibility of combining in the field smart phone images with color dependent assay results, ii) to develop a MatLab® image analysis code to analyze these results, and iii) compare limits of detection between the un-aided eye and MatLab® image analysis software. Orange G dye is used to create a stock solution and subsequent titers for analysis. Autocad is used to design an assay platform of 10x10 wells that are printed via a Xerox® Phaser printer with wax ink onto nitrocellulose paper. Dilutions are performed and pipetted into the wells. The image analysis code is used to determine hue, saturation, and value (HSV) values of wells. A limit of detection study using the dye is performed. HSV values are used to form calibration curves. The resulting curve fit equations are then integrated into the image analysis code to determine dye concentration. Finally, the complete capability is demonstrated by using an analogous 10x10 well experimental nitrocellulose sheet, which included a follow-up experiment via a spot check analysis. This study illustrates the feasibility of a low cost image analysis as a tool for lateral flow assay diagnostic versus the unaided eye. Future work includes using this protocol in conjunction with a lateral flow immunoassay and developing an application for the analysis.

Point-of-care testing (POCT) is defined as medical testing at or near the site of patient care and has become a critical component of the diagnostic industry. POCT has many advantages over tests in centralized laboratories including small reagent volumes, small size, rapid turnaround time, cost-effectiveness, low power consumption and functional integration of multiple devices. Paper-based POCT sensors are a new alternative technology for fabricating simple, low-cost, portable and disposable analytical devices for clinical diagnosis. The focus of this dissertation was to develop simple, rapid and low cost paper-based POCT sensors with high sensitivity and portability for disease biomarker detection. Lateral flow strips (LFS) were used as the basic platform as it provides several key advantages such as simplicity, fast response time, on site and cost-effectiveness, and it can be used to detect specific substances including small molecules, large proteins and even whole pathogens, in a sample by immunological reactions. Earlier designs of paper strips lacked the quantitative information of the analyte concentration and could only provide single analyte detection at a time. In this study, a series of modifications were made to upgrade the platform to compensate for these limitations. First, we developed a gold nanoparticle based LFS for qualitative colorimetrical detection of bladder cancer related biomarkers in standard solutions and in urine samples. Second, by incorporating an image processing program “ImageJ”, a semi-quantitative LFS platform was established. The capability of the strip was evaluated by testing a small DNA oxidative damage biomarker in urine and cell culture models. Third, we combined the electrochemical method and colorimetrical method for quantitative biomarker detection. Finally, we integrated a commercialized blood glucose meter to quantitatively detection of two non-glucose biomarkers by converting their signals to that of glucose. The upgraded sensor could provide a noninvasive, rapid, visual, quantitative and convenient detection platform for various disease biomarkers. In addition, this platform does not require expensive equipments or trained personnel, deeming it suitable for use as a simple, economical and portable field kit for on-site biomarker monitoring in a variety of clinical settings.

Fästingburet encefalitvirus (TBEV) är ett RNA-virus som tillhör genuset flavivirus. Vid en TBEV-infektion är feber, trötthet, allmänpåverkan samt huvudvärk och muskelvärk vanligt förekommande symtom. Viruset överförs via saliven från fästingar under de första minuterna efter fästingbett. TBEV-IgM och ibland även TBEV-IgG återfinns i serum då symtom i centrala nervsystemet (CNS) yttrar sig i den andra fasen av sjukdomsförloppet. De senaste åren har prevalensen av fästingburen encefalit (TBE) ökat. Sedan 2017 har över 300 fall av TBE rapporterats årligen i Sverige. Laterala flödesanalyser (lateral flow assays, LFA) är billiga, enkla, snabba och baseras på portabla instrument som används bland annat inom biomedicinsk vetenskap. ReaScan® TBE IgM från det finska företaget Reagena är ett snabbtest, baserat på LFA-tekniken, för detektion av TBE-specifika IgM-antikroppar i humant serum och likvor. Syftet med studien var att undersöka om ReaScan® TBE IgM kan användas för att diagnostisera TBE på laboratoriet för Klinisk Mikrobiologi på länssjukhuset i Kalmar. Metodens prestanda undersöktes genom att analysera totalt 23 serumprover, 13 prover från TBE-patienter och 10 prover från icke-TBE-patienter. Sensitiviteten uppskattades genom att analysera 13 serumprover där förekomst av TBE-antikroppar sedan tidigare konfirmerats. Specificiteten uppskattades genom att analysera 10 serumprover från patienter utan känd TBEV-infektion. Den diagnostiska sensitiviteten respektive specificiteten beräknades till 100 %. På grund av den begränsade storleken på undersökningsmaterialet är dock den beräknade sensitiviteten och specificiteten ej helt tillförlitlig. Metodens prestanda ansågs vara tillräckligt god för att den skall kunna användas som en screening-metod för TBEV-IgM-antikroppar på laboratoriet för Klinisk Mikrobiologi på länssjukhuset i Kalmar. / Tick-borne encephalitis virus (TBEV) is an RNA virus that belongs to the genus flavivirus. Symptoms that commonly present during a TBEV infection include headaches, muscle pains, fever and malaise. The virus is transmitted with the saliva from ticks during the first minutes of their blood meal. TBEV-IgM and sometimes TBEV-IgG antibodies can be detected in the patient’s serum when central nervous system (CNS) symptoms present in the second phase of the disease. Over the last couple of years, the prevalence of tick-borne encephalitis (TBE) has increased. Since 2017 over 300 cases of TBE are reported every year in Sweden. Lateral flow assays (LFA) is the technology behind inexpensive, simple, quick and portable instruments that are used within the biomedical science field among others. ReaScan® TBE IgM developed by the Finnish company Reagena is a rapid test, based on the LFA technique, used for the detection of TBEV specific IgM antibodies in human serum and cerebrospinal fluid. The trial aimed to evaluate whether ReaScan® TBE IgM could be used to diagnose TBE at the laboratory of Clinical microbiology at the County hospital in Kalmar. The performance of the test was determined by analysing a total of 23 serum samples, 13 of which consisted of samples from patients with a previously confirmed TBE diagnosis and 10 samples from patients with no known TBEV infection. The diagnostic sensitivity and specificity were both determined to be 100 %. Due to the limited sample size, the calculated sensitivity and specificity are not particularly reliable.  The performance of the test was satisfactory and it could be used as a screening method for the detection of TBEV IgM antibodies at the department of Clinical microbiology at Kalmar County Hospital.

Existing methods for pathogen/pollutant detection or wound infection monitoring employ high-cost instruments that could only be operated by trained personnel, and costly device-based detection requires a time-consuming field-to-lab process. This expensive process with multiple prerequisites prolongs the time that patients must wait for a diagnosis. Therefore, improved methods for point-of-care biosensing are necessary. In this study, we aimed to develop a direct, easy-to-use, portable, low cost, highly sensitive and selective sensor platform with the goal of pollutant detection and wound infection/cancer migration monitoring. This study has two main parts, including microfluidic, electrical, and optical sensing platforms. The first part, including chapters 2, 3, and 4, focuses on Bisphenol A (BPA) lateral flow assay (LFA) detection; the second part, including chapter 5 focuses on the electrical sensing platform fabrication for one of the markers of inflammation, matrix metalloproteinases-9 (MMP-9), monitoring/detection. In chapters 2, 3, and 4, we found that the few lateral flow assays (LFAs) established for detecting the endocrine-disrupting chemical BPA have employed citrate-stabilized gold nanoparticles (GNPs), which have inevitable limitations and instability issues. To address these limitations, in chapter 2, a more stable and more sensitive biosensor is developed by designing strategies for modifying the surfaces of GNPs with polyethylene glycol and then testing their effectiveness and sensitivity toward BPA in an LFA. In chapter 3, we describe the development of a new range-extended bisphenol A (BPA) detection method that uses a surface enhanced Raman scattering lateral flow assay (SERS-LFA) binary system. In chapter 4, we examine advanced bisphenol A (BPA) lateral flow assays (LFAs) that use multiple nanosystems. The assays include three nanosystems, namely, gold nanostars, gold nanocubes, and gold nanorods, which are rarely applied in LFAs, compared with general gold nanoparticles. The developed LFAs show different performances in the detection of BPA. In chapter 5, a stable electrical sensing platform is developed for MMP-9 detection.

Trifft herabfallender Regen auf Waldflächen, so wird dieser Niederschlag umverteilt zu Interzeption, Stammabfluss, durchfallenden und abtropfenden Niederschlag. Besonders hohe Stammablaufmengen im Kronenzentrum und markante Abtropfstellen am Kronenrand einzelner Baumarten lassen sich zudem nur erklären, wenn am jeweiligen Messplatz unter Baumkronen eine weitere Niederschlagskomponente zugelassen wird, mit der laterale Wasserbewegungen innerhalb der expliziten Einzelbaumkrone beschrieben und bilanziert werden (lateraler [Zu- oder Ab-]Fluss). Ziel dieser Arbeit war es deshalb, der niederschlagsabhängigen und kleinräumigen Dynamik dieser Umverteilung im Wald am Beispiel der Baumarten Buche (Fagus sylvatica L.) und Fichte (Picea abies (L.) Karst.) durch Aufnahmen und Auswertungen in zwei Mischbeständen beider Baumarten nachzugehen. Wiederholende Niederschlagsaufzeichnungen einzelner Regenereignisse wurden hierzu in Relation zur jeweiligen Freilandniederschlagsmenge, zur Art der Messplatzüberschirmung im Kronendach und zur Distanz des Messplatzes zum ihn dominierenden Baum varianz- und regressionsanalytisch untersucht und um Ergebnisse aus Stammablaufanalysen und Streumodellen ergänzt. Auf dieser Basis konnten Kausalmodelle zur Schätzung des Unterkronenniederschlages mit hoher Güte hergeleitet werden, die im Detail ein baumartspezifisches räumliches Verhalten der einzelnen Niederschlagskomponenten beim Passieren der Baumkrone belegen. Neben den Besonderheiten, die sich bei Messungen in Bestandeslücken einstellen, ergeben sich so z.B. in der Vegetationsperiode je nach Messplatzposition und Freilandniederschlagsmenge Unterschiede im Niederschlag unter beiden Baumartenkronen von bis zu 35 % des Freilandniederschlages je Einzelereignis und zwar stets zugunsten der Buchenüberschirmung. Am Stammfuss von Buchen kann darüber hinaus zusätzliches Wasser durch den Stammabfluss eingetragen werden. Hierfür notwenige Wassermengen können plausibel aus dem nachgewiesenen lateralen Wasserabfluss im inneren Kronendrittel von Buchen gedeckt werden. Über ein räumlich konkretes Interzeptionsmodell, kombiniert mit Blattflächenschätzungen für Einzelbäume konkreter Dimension, konnte ein räumliches LAI-Modell für Buchen abgeleitet werden, dass höchste LAI-Werte im Kronenzentrum annimmt. Da der Bestandesniederschlag hinsichtlich Niederschlagsmenge, Bestockung, Belaubungszustand und zum räumlich konkreten Messplatz unter der einzelnen Baumkrone veränderlich ist, wird die gewissenhaftere Berücksichtigung dieser Einflussvariablen angeregt und der bisher häufig praktizierten pauschalen Aufteilung des Niederschlages in einzelne Niederschlagskomponenten auf Basis von Flächen- und Messphasendurchschnittswerten widersprochen. / Forests redistribute the precipitation falling on their canopy into interception, stemflow, drip or direct throughfall. Extremely high amounts of stemflow in the centre of the crown and distinct drip points along the crown edge of certain tree species can only be explained by admitting an additional precipitation component at these measurement locations that describes and captures the lateral movement of water within the individual tree crown (lateral in- or outflow). The aim of this study was therefore to analyse these precipitation-dependent, small-scale dynamics of precipitation redistribution in forests using field-measurements from two mixed stands of European beech (Fagus sylvatica L.) and Norway spruce (Picea abies (L.) Karst.). Periodic measurements of individual precipitation events were examined in relation to the respective gross precipitation, the type of canopy above a plot and the distance of a plot to its dominant sheltering canopy tree using variance and regression analysis, and complemented with stemflow analyses and litterfall models. Using this dataset, causal models for the high-precision estimation of throughfall were derived, showing tree species-specific pathways of the individual precipitation components through the tree crown. Apart from the particularities of measurements in canopy gaps, differences in throughfall between spruce and beech during the vegetation period amount to up to 35 % of gross precipitation per event, in favour of the beech canopy and depending on plot location. At the stem base of beech trees additional water can reach the forest floor via stemflow. The amount of water required to generate this stemflow can plausibly be explained by means of the verified lateral water flow in the inner third of beech crowns. Using a spatially explicit interception model combined with LAI estimates for specific individual trees, a spatial LAI model was developed for beech, showing maximal LAI values in the crown centre. As the net forest precipitation is sensitive with respect to precipitation amount, stand type, foliage status and the spatially explicit plot location below an individual tree crown, this study recommends the consideration of these influential factors and contradicts the commonly practiced blanket partitioning of precipitation into individual components based on spatial and temporal averages.

Submitted by Priscila Nascimento (pnascimento@icict.fiocruz.br) on 2012-11-09T13:57:11Z No. of bitstreams: 1 antonio-gomes-pinto-ferreira.pdf: 3200920 bytes, checksum: 45691c2f346703ac5db93dd4465b77f3 (MD5) / Made available in DSpace on 2012-11-09T13:57:11Z (GMT). No. of bitstreams: 1 antonio-gomes-pinto-ferreira.pdf: 3200920 bytes, checksum: 45691c2f346703ac5db93dd4465b77f3 (MD5) Previous issue date: 2005-03 / Fundação Oswaldo Cruz. Instituto de Tecnologia em Imunobiológicos. Rio de Janeiro, RJ, Brasil / Fundação Oswaldo Cruz. Instituto Oswaldo Cruz. Rio de Janeiro, RJ, Brasil. / Nesta dissertação apresentamos o modelo utilizado pelo Instituto de Tecnologia em Imunobiológicos, Bio-Manguinhos, Fiocruz, para absorver uma nova tecnologia de produção de reativos para diagnóstico, de alta complexidade (imunocromatografia e fluxo lateral) e estratégico para a área de saúde de nosso país. Inicialmente, porque permitirá a produção de um Kitde diagnóstico (“Teste Rápido HIV-1/2 – Bio-Manguinhos”), de alto impacto social, indispensável para ampliar as ações de saúde pública em DST/Aids e, emseguida porque será capaz de democratizar o diagnóstico da infecção pelo HIV no Brasil. A absorção desta nova tecnologia redundará em uma economia de divisas para o Brasil com a conseqüente interrupção de grandes compras de Kits importados, além de gerar um potencial a ser futuramente usado no desenvolvimento e produçãode Kits para o diagnóstico de outras importantes enfermidades que acometem a população brasileira, com baixo custo. Finalmente, devido às repercussões positivasem outros setores relacionados à produção, melhorando e fortalecendo a área de Reativos para Diagnóstico de Bio-Manguinhos. Estes são argumentos significativos para a implementação deste projeto baseado em transferência de tecnologia. Bio-Manguinhos estabeleceu as articulações necessárias junto ao Ministério da Saúde, especialmente junto ao PNDST/Aids, utilizando a “demanda do setor público brasileiro”, por um período de três anos, como contrapartida nas negociações com a empresa cedente da tecnologia, evitando, desta forma, qualquer gasto adicional de recursos públicos para absorver as referidas tecnologias. A Aids, ou SIDA, ainda é um dos maiores problemas de saúde pública no mundo, apresentando números absolutamente alarmantes – cerca de 40 milhões de pessoas infectadas pelo HIV, 5 milhões de novos casos por ano e 3,5 milhões de óbitos em 2004. No Brasil, apesar de ser adotada uma boa política de assistência e tratamento, que vem sendo citada como exemplo no mundo inteiro, ainda convivemos com uma epidemia que continua a se alastrar em ritmo preocupante, com estimativa de 600.000 brasileiros infectados. Atualmente, estamos presenciando uma revolução científica e tecnológica impar e, neste contexto, Bio-Manguinhos vem tendo como missão “contribuir para a melhoria dos padrões de saúde pública brasileira, através da pesquisa tecnológica e da produção de imunobiológicos necessários para atender à demanda gerada pelo quadro epidemiológico do país”. Assim, esta Instituição vem investindo, intensamente, em projetos de pesquisa e desenvolvimento (P&D), bem como na aquisição e incorporação de novas tecnologias para a produção, em escala industrial, de produtos capazes de suprir as demandas dos programas nacionais de saúde pública do Ministério da Saúde. Neste contexto, vem seguindo as tendências na área de Reativos para Diagnóstico laboratorial que estão voltadas, principalmente, para uma melhor orientação da conduta terapêutica com diagnósticos mais precisos, diferenciais e mais precoces na detecção das doenças, maior rapidez nos resultados e realização dos testes afins nos próprios locais de atendimento de pacientes. / This dissertation describes the model adopted by Bio-Manguinhos in the incorporation of a brand-new technology (immunochromatography and lateral flow) for the production of reagents for diagnosis. This technology is strategic and extremely valuable for the country, as it allows for the production of a low-cost diagnostic kit (Rapid Test HIV-1/2 – Bio-Manguinhos) that will, in turn, promote the dissemination of more extensive public health measures in the prevention and control of STD/Aids, including the socialization of HIV diagnosis in Brazil. Also, the substitution of large bulks of imported tests by their nationally produced equivalent will result in great, monetary savings by the Brazilian Ministry of Health and that the technological platform applied in such tests can also be used in the development of rapid tests designed for the diagnosis of other endemic diseases that afflict the Brazilian population. Finally, due to the positive repercussions it may have on other production sectors, this initiative will ameliorateand strengthen the area of Reagents for Diagnosis in Bio-Manguinhos. All of these arguments, represented strong incentives for the establishment of the partnership, being essential for the implementation of the technology transfer process. Bio-Manguinhos undertook the necessary negotiationswith MoH, especially with the National Program for STD/Aids, offering a share of the Brazilian public market for a period of three years in exchange for the technology to be transferred by the American company that detains it, thus avoidingany extra use of public funds by the Brazilian government. Aids is still one of the biggest public health problems in the world today, presenting impacting figures: approximately 40 million people are infected with HIV worldwide, with 5 million new cases diagnosed per year and 3.5 million deaths being reported in 2004. Despite Brazil´s policy for universal Aids treatment and assistance coverage – which is considered an example for the rest of the world – the country, with its estimated 600,000 HIV positive citizens, still deals with an epidemic that continues to spread at alarming rates. Certainly, much is yet expected to result from today´s scientific and technological revolution. Within this context, Bio-Manguinhos, whose mission is to “contribute to the improvement of the Brazilian public health standards through technological research and development and the production of immunobiologicals necessary for the fulfillment of the demands generated by the country´s epidemiological status”, has been investing heavily in R&D projects as well as in the acquisition and incorporation of new technologies for the large scale manufacture of products that will feed MoH´s national public health programs. One of the new tendencies in the field of reagents for laboratorial diagnosis is geared toward guiding a better therapeutic approach and calls for a more precise, differential and early disease diagnosis. The time required to obtain results also tends to be shorter and the tests, designed in much simpler formats, can beperformed faster, without need for extensive professional expertise or fully – equipped facilities.

Trifft herabfallender Regen auf Waldflächen, so wird dieser Niederschlag umverteilt zu Interzeption, Stammabfluss, durchfallenden und abtropfenden Niederschlag. Besonders hohe Stammablaufmengen im Kronenzentrum und markante Abtropfstellen am Kronenrand einzelner Baumarten lassen sich zudem nur erklären, wenn am jeweiligen Messplatz unter Baumkronen eine weitere Niederschlagskomponente zugelassen wird, mit der laterale Wasserbewegungen innerhalb der expliziten Einzelbaumkrone beschrieben und bilanziert werden (lateraler [Zu- oder Ab-]Fluss). Ziel dieser Arbeit war es deshalb, der niederschlagsabhängigen und kleinräumigen Dynamik dieser Umverteilung im Wald am Beispiel der Baumarten Buche (Fagus sylvatica L.) und Fichte (Picea abies (L.) Karst.) durch Aufnahmen und Auswertungen in zwei Mischbeständen beider Baumarten nachzugehen. Wiederholende Niederschlagsaufzeichnungen einzelner Regenereignisse wurden hierzu in Relation zur jeweiligen Freilandniederschlagsmenge, zur Art der Messplatzüberschirmung im Kronendach und zur Distanz des Messplatzes zum ihn dominierenden Baum varianz- und regressionsanalytisch untersucht und um Ergebnisse aus Stammablaufanalysen und Streumodellen ergänzt. Auf dieser Basis konnten Kausalmodelle zur Schätzung des Unterkronenniederschlages mit hoher Güte hergeleitet werden, die im Detail ein baumartspezifisches räumliches Verhalten der einzelnen Niederschlagskomponenten beim Passieren der Baumkrone belegen. Neben den Besonderheiten, die sich bei Messungen in Bestandeslücken einstellen, ergeben sich so z.B. in der Vegetationsperiode je nach Messplatzposition und Freilandniederschlagsmenge Unterschiede im Niederschlag unter beiden Baumartenkronen von bis zu 35 % des Freilandniederschlages je Einzelereignis und zwar stets zugunsten der Buchenüberschirmung. Am Stammfuss von Buchen kann darüber hinaus zusätzliches Wasser durch den Stammabfluss eingetragen werden. Hierfür notwenige Wassermengen können plausibel aus dem nachgewiesenen lateralen Wasserabfluss im inneren Kronendrittel von Buchen gedeckt werden. Über ein räumlich konkretes Interzeptionsmodell, kombiniert mit Blattflächenschätzungen für Einzelbäume konkreter Dimension, konnte ein räumliches LAI-Modell für Buchen abgeleitet werden, dass höchste LAI-Werte im Kronenzentrum annimmt. Da der Bestandesniederschlag hinsichtlich Niederschlagsmenge, Bestockung, Belaubungszustand und zum räumlich konkreten Messplatz unter der einzelnen Baumkrone veränderlich ist, wird die gewissenhaftere Berücksichtigung dieser Einflussvariablen angeregt und der bisher häufig praktizierten pauschalen Aufteilung des Niederschlages in einzelne Niederschlagskomponenten auf Basis von Flächen- und Messphasendurchschnittswerten widersprochen. / Forests redistribute the precipitation falling on their canopy into interception, stemflow, drip or direct throughfall. Extremely high amounts of stemflow in the centre of the crown and distinct drip points along the crown edge of certain tree species can only be explained by admitting an additional precipitation component at these measurement locations that describes and captures the lateral movement of water within the individual tree crown (lateral in- or outflow). The aim of this study was therefore to analyse these precipitation-dependent, small-scale dynamics of precipitation redistribution in forests using field-measurements from two mixed stands of European beech (Fagus sylvatica L.) and Norway spruce (Picea abies (L.) Karst.). Periodic measurements of individual precipitation events were examined in relation to the respective gross precipitation, the type of canopy above a plot and the distance of a plot to its dominant sheltering canopy tree using variance and regression analysis, and complemented with stemflow analyses and litterfall models. Using this dataset, causal models for the high-precision estimation of throughfall were derived, showing tree species-specific pathways of the individual precipitation components through the tree crown. Apart from the particularities of measurements in canopy gaps, differences in throughfall between spruce and beech during the vegetation period amount to up to 35 % of gross precipitation per event, in favour of the beech canopy and depending on plot location. At the stem base of beech trees additional water can reach the forest floor via stemflow. The amount of water required to generate this stemflow can plausibly be explained by means of the verified lateral water flow in the inner third of beech crowns. Using a spatially explicit interception model combined with LAI estimates for specific individual trees, a spatial LAI model was developed for beech, showing maximal LAI values in the crown centre. As the net forest precipitation is sensitive with respect to precipitation amount, stand type, foliage status and the spatially explicit plot location below an individual tree crown, this study recommends the consideration of these influential factors and contradicts the commonly practiced blanket partitioning of precipitation into individual components based on spatial and temporal averages.

No description available.