O conhecimento das respostas morfofisiológicas da planta sobre as condições edafoclimáticas específicas de cada região é fundamental para determinação de recomendações de manejo da desfolhação e adubação mais eficientes que favoreçam a interface solo-planta. Assim, objetivou-se avaliar o melhor momento de corte do capim-Marandu (Urochloa Brizantha cv. Marandu) submetido a diferentes níveis de adubação (zero-00:00:00, baixa-100:32:100, média-170:55:170 e alta-240:78:240 de N-P2O5-K2O) associado a diferentes momentos de desfolhação (90, 95 e 100% de interceptação da luminosidade) para distintas estações do ano (transição seca/água – S/A, período das águas – A e água/seca – A/S). Para tanto foram conduzidos dois trabalhos, sendo o primeiro para determinar o efeito dos níveis de adubação e o segundo para avaliar o efeito da interceptação da radiação fotossinteticamente ativa – IRFA sobre o desempenho do capim-Marandu nas épocas do ano. O trabalho foi composto por parcelas de 4x3 m² com três repetições por tratamento, as quais foram distribuídas em delineamento inteiramente casualizado (DIC). O primeiro trabalho foi avaliado em medidas repetidas no tempo e o segundo em arranjo fatorial 4x3. A densidade populacional de perfilhos (DPP perfilho-1 m2), altura (cm) e o índice de área foliar (IAF m2 m2) foram fortemente influenciados pelas estratégias de adubação, mas foram estáveis após a primeira época de avaliação. A taxa de senescência (TSF) demostrou ser bastante variável com as épocas do ano, em que a menor adubação teve um incremento na TSF diária de 30,2% em comparação com a maior adubação. As taxas de alongamento foliar (TAlF mm perfilho-1 dia-1), taxa de alongamento de colmo (TAlC mm perfilho-1 dia-1) e Filocrono (FILOR dias-1 folha-1) foram influenciadas pelas épocas do ano, as quais proporcionaram as maiores TAlF e TAlC na época S/A, o FILOR tendeu a diminuir com a elevação da fertilidade do solo sendo em média o menor valor de 9,6 dias-1 folha-1 obtido para a adubação alta e dentre as épocas o menor valor obtido para FILOR foi na estação S/A com média de 9,1 dias-1 folha-1. A duração de vida das folhas (DVF dias) não se mostrou flexível aos tratamentos, o comprimento de bainha (CB mm perfilho-1) e o número de folhas vivas (NFV folhas-1 perfilho-1) mostraram-se bastante influenciados pelos tratamentos e principalmente pela época do ano, onde o maior CB foi obtido na estação S/A com média de 359,6 mm-1 perfilho-1, proporcionado principalmente pelo baixo número de perfilhos que resultou em maior CB para atingir a meta alvo de 95% de IRFA, bem como para a mesma época foram obtidos os maiores NFV com média de 4,9 folhas-1 perfilho-1. As massa seca total (MST kg ha-1), de lâmina foliar (MSLF kg ha-1), colmo (MSC kg ha-1) e material morto (MSMM kg ha-1) foram influenciadas pelos tratamentos, onde tanto a elevação da fertilidade quanto a interceptação da luminosidade elevaram a produção de matéria seca (MS), entretanto, o incremento proporcionado após o IAFcrítico foi principalmente pelo aumento de colmo e material morto, e essa resposta promoveu a redução da relação F/C, o que resultou também na diminuição do índice SPAD, que passou de 18,3 na IRFA de 90% para 11,2 na IRFA de 100%, essa queda, demostra redução no estado nutricional da planta. A taxa de acumulo de forragem (TAF kg ha-1 dia-1) foi influenciada pelas estratégias de adubação, onde a maior adubação proporcionou um incremento de 204,6% na TAF em comparação a dose zero. Assim, é possível concluir que as características morfogênicas e estruturais do capim-Marandu, bem como sua produção forrageira são fortemente influenciadas pelas estações de crescimento e pelo manejo da adubação, sendo fundamental a realização da adubação associada as condições ambientais favoráveis para uma boa produção forrageira tanto quantitativa quanto qualitativa. Por fim, a altura do dossel próxima os 40 cm coincide com o IAFcrítico, sendo esse o momento ótimo para a desfolhação da planta sob os fatores edafoclimáticos de condições tropicais. / Knowledge of the morphological and physiological responses of the plant on the specific soil and climatic conditions of each region is fundamental for determining management of defoliation recommendations and more efficient fertilizer to encourage the soil-plant interface. The objective was to evaluate the best time to cut the palisadegrass Marandu (Urochloa brizantha cv. Marandu) submitted to different levels of fertilization (zero-00:00:00, low-100:32:100, medium-170: 55 170 and High-240:78:240 N-P2O5-K2O) associated with different times of defoliation (90, 95 and 100% light interception) for different seasons (transition dry/water - D/W, period of the water - W and the water/dry - W/D). Therefore we conducted two studies, the first to determine the effect of fertilizer levels and the second to assess the effect of interception of photosynthetically active radiation - IRPA on the performance of palisadegrass Marandu the seasons. The work was composed of portions of 4x3 m² with three replicates per treatment, which were distributed in a completely randomized design (CRD). The first work was evaluated in repeated measurements over time and the second in a factorial arrangement 4x3. The tiller population density (TPD tiller-1 m2), height (cm) and leaf area index (LAI m2 m2) were strongly influenced by fertilization strategies but were stable after the first evaluation. The senescence rate leaf (SRL) has shown to be quite variable with the seasons, in which the lower fertilization had an increase in 30,2% daily SRL compared to higher fertilization. The leaf elongation rate (LER mm tiller-1 day-1), stem elongation rate (SER mm tiller-1 day-1) and Phyllochron (PHYLLO days-1 sheet-1) were influenced by the seasons of the year, which provided the highest LER and SER at the time D/W, the PHYLLO tended to decrease with increasing soil fertility and on average the lowest value of 9,6 days-1 leaf-1 obtained for the high fertilization and among the seasons the lowest value obtained for PHYLLO was at the station D/W with an average of 9,1 days-1 leaf-1. The lifetime leaf (LTL days) was not flexible to treatment, the length of sheath (LS mm tiller-1) and the number of living leaves (NLL sheets-1 tiller-1) proved to be greatly influenced by the treatments and especially the time of year where the largest LS was obtained at the station D/W with an average of 359,6 mm-1 tiller-1, provided mainly by the low number of tillers that resulted in higher LS to reach the goal target 95% of IRPA and for the same period showed the highest NLL with an average of 4,9 leaves-1 tiller-1. The total dry matter (TDM kg ha-1) of leaf blade (DMLB kg ha-1), stem (DMS kg ha-1) and dead material (DMDM kg ha-1) were influenced by the treatments, which both rise fertility as the interception of light increased the production of dry matter (DM), however, the increase provided after LAIcrítical was mainly due to the increase of stem and dead material, and this response promoted the reduction in the ratio L/S, which resulted also decreasing the SPAD index, which rose from 18,3 in 90% IRPA to 11,2 in IRPA 100%, this fall, demonstrates reduction in the nutritional status of the plant. The accumulation rate of forage (ARF kg ha-1 day-1) was influenced by fertilization strategies, where most fertilization provided an increase of 204,6% in ARF compared to zero dose. Thus, we conclude that the morphogenetic and structural characteristics of palisadegrass Marandu and their forage production are strongly influenced by growing seasons and the management of fertilization is fundamental to the realization of fertilization associated with favorable environmental conditions for good forage production both quantitative and qualitative. Finally, the next time the canopy 40 cm coincides with the LAIcrítico, which is the optimal time for the defoliation of the plant under edafoclimatic factors tropical conditions.

A área plantada com eucaliptos no Brasil cresceu a uma taxa de 4,7% ao ano nos últimos 7 anos (ABRAF, 2013). Os impactos que as plantações tendem a ocasionar nos recursos hídricos podem ser incertos e imprecisos quando do não conhecimento do clima, solo e espécie plantada. Nesse contexto, o balanço hídrico é uma abordagem largamente recomendada para a boa avaliação e tomada de decisão nos processos hidrológicos. O objetivo deste trabalho foi quantificar experimentalmente o balanço hídrico e a erosão do solo numa plantação de Eucalyptus grandis ainda em idade jovem (entre 2 e 3 anos) durante um ano. A instalação experimental foi locada no município de Brotas - SP, a 35 km da cidade de São Carlos. Foram utilizados dois métodos para a coleta da Precipitação interna (Pi) na plantação: calhas e pluviômetros, para verificação estatística. Concluiu-se que a Pi coletada por calhas e pluviômetros são estatisticamente semelhantes, porém o desvio padrão médio dos valores coletados pelas calhas é menor. O Escoamento fustal (Ef) foi coletado com o auxílio de fitas adesivas e mangueiras coladas a 10 troncos, e armazenado em galões. O Escoamento superficial (Es) e os sedimentos provenientes da erosão do solo foram coletados em parcelas experimentais de 100 m² (5,0 x 20,0 m) com a maior dimensão no sentido do escoamento, numa área com declividade de aproximadamente 10%. Os resultados mostram que a Perda por Interceptação (It) correspondeu a 13,0% da Precipitação total (Pt) registrada em 2013. O Ef correspondeu a 2,4% de Pt, não podendo ser desprezado na parcela da It da plantação. O valor de Es foi baixo (0,6% de Pt), pois o solo da área de pesquisa era bastante arenoso (86%). Os valores diários de Evapotranspiração real (Et) foram estimados pela equação de Penman, e resultaram em 938,0 mm no ano de 2013. O valor da Recarga direta (Rd) foi estimado em 250,8 mm, o que está de acordo com trabalhos realizados anteriormente na mesma região. A erosão do solo na plantação foi de 2,21 Mg.ha-1 no ano de 2013, sendo a lâmina d\'água e a intensidade máxima da precipitação os principais fatores que provocaram as maiores erosões. / The planted area of eucalyptus in Brazil increased in a rate of 4.7% per year in the last 7 years (ABRAF, 2013). The impacts of the plantations in the water resources tend to lead to uncertainty and inaccuracy on the knowledge of the climate, soil and planted specie. In this context, the water balance is a largely recommended approach on the decision-making regarding the hydrological processes. The main objective of this work was to quantify experimentally the water balance and the soil erosion in an Eucalyptus grandis plantation still in young ages (between 2 and 3 years old) over one year. The experimental installation was set in Brotas - SP, 35 km away from the city of São Carlos. Two methods were utilized to collect the throughfall (Pi): transects and rain gauges, aiming a statistical verification. The result suggests that Pi collected by transects and rain gauges are statistically similar, but the mean standard deviation of the transects is smaller. The Stemflow (Ef) was collected with adhesive tapes connected to 10 stems, and stored in gallons. The Stream flow (Es) and the soil erosion were collected in experimental catchments of 100 m2 (5.0 x 20.0 m) with the largest dimension towards the flow, in an area with 10% of slope. The results showed that the Interception loss (It) corresponded to 13.0% of the Gross rainfall (Pt) registered in 2013. The Ef corresponded to 2.4% of the Pt, proving that it can\'t be neglected on the It calculation. The value of Es was low (0.6% of Pt), because the soil of the catchment was very sandy (86%). The daily values of Evapotranspiration (Et) were estimated by using the Penman-Monteith equation, resulting in 938.0 mm in 2013. The value of Direct recharge (Rd) was estimated in 250.8 mm, and according to previous works done in the same region, it is consistent. The soil erosion in the plantation was 2.21 Mg.ha-1, being the rain depth and the maximum rain intensity the main factors that caused biggest erosions.

Sob a perspectiva de aumento da demanda global por biocombustíveis, em particular o etanol durante as próximas décadas, espera-se um crescimento ainda maior da indústria sucroalcooleira no Brasil. Aliada à expansão da cultura da cana-de-açúcar, as bacias nas quais se inserem esses plantios estão sujeitas a alterações no regime hidrológico, bem como à elevação do uso de fertilizantes nitrogenados, o que possui implicações na quantidade e qualidade da água nos corpos hídricos. Com intuito de avaliar esses impactos, o presente estudo visou caracterizar as vias hidrológicas e o transporte de nitrogênio associado a elas em vertentes cobertas por cana-de-açúcar localizadas em microbacias do Rio Corumbataí, noroeste do estado de São Paulo. Para isso, foram monitorados alguns processos hidrológicos, entre eles: precipitação total, precipitação interna, escoamento pelo caule, escoamento superficial, umidade do solo em quatro profundidades (15 cm, 30 cm, 50 cm e 90 cm) e deflúvio durante período de 21 de julho de 2012 a 22 de maio de 2013. A precipitação totalizou 1095 mm durante o período de estudo, dos quais em torno de 35% foram interceptados pela cultura. Não foram encontradas diferenças significativas entre o efeito de diferentes variedades de cana-de-açúcar no que se refere às perdas por interceptação. Além dessa, a parcela de água de chuva escoada pelo caule, a precipitação interna, o escoamento superficial e o deflúvio corresponderam, respectivamente, a 14%, 51%, 4,7% e 7,7% do total precipitado. Nesses compartimentos hidrológicos, de um modo geral, foram observadas baixas concentrações de nitrogênio, com exceção ao escoamento superficial, que apresentou altas concentrações, principalmente de nitrato. O aporte (deposição) de nitrogênio ao sistema, 2,81 kg N ha-¹, foi superior à perda fluvial: 0,45 kg N ha-¹ / The recent years have shown us that there is a perspective of increasing the global biofuels demand, particularly ethanol. In conjunction with the expansion of sugarcane crop, the watersheds in which these crops are founded are subject to hydrological changes, as well as the elevation of the use of nitrogen fertilizers. It has implications in the quantity and quality of water in streams. In order to assess these impacts, the present study aimed to characterize the hydrological flow paths and the associated nitrogen transport in hillslopes under sugarcane in two small watersheds at Corumbataí River, northwest of São Paulo. For this, we monitored some hydrological flow paths, including: gross rainfall, throughfall, stemflow, surface runoff, soil moisture at four depths (15 cm, 30 cm, 50 cm and 90 cm) and streamflow during period of 21 July 2012 to May 22, 2013. Gross rainfall was 1095 mm and around 35% was intercepted by the sugarcane canopy. No significant differences between different varieties of sugarcane were found for interception losses. In addition, rainfall was partitioned into stemflow, throughfall, surface runoff and streamflow as the following: 14%, 51%, 4.7% and 7.7%, respectively. Hydrological flow paths in general carried low nitrogen concentration, being the surface runoff the exception, which carried high levels of nitrate. The nitrogen input in the system was 2.81 kg N ha-¹, and the loss by streamflow was 0.45 kg N ha-1

Sob a perspectiva de aumento da demanda global por biocombustíveis, em particular o etanol durante as próximas décadas, espera-se um crescimento ainda maior da indústria sucroalcooleira no Brasil. Aliada à expansão da cultura da cana-de-açúcar, as bacias nas quais se inserem esses plantios estão sujeitas a alterações no regime hidrológico, bem como à elevação do uso de fertilizantes nitrogenados, o que possui implicações na quantidade e qualidade da água nos corpos hídricos. Com intuito de avaliar esses impactos, o presente estudo visou caracterizar as vias hidrológicas e o transporte de nitrogênio associado a elas em vertentes cobertas por cana-de-açúcar localizadas em microbacias do Rio Corumbataí, noroeste do estado de São Paulo. Para isso, foram monitorados alguns processos hidrológicos, entre eles: precipitação total, precipitação interna, escoamento pelo caule, escoamento superficial, umidade do solo em quatro profundidades (15 cm, 30 cm, 50 cm e 90 cm) e deflúvio durante período de 21 de julho de 2012 a 22 de maio de 2013. A precipitação totalizou 1095 mm durante o período de estudo, dos quais em torno de 35% foram interceptados pela cultura. Não foram encontradas diferenças significativas entre o efeito de diferentes variedades de cana-de-açúcar no que se refere às perdas por interceptação. Além dessa, a parcela de água de chuva escoada pelo caule, a precipitação interna, o escoamento superficial e o deflúvio corresponderam, respectivamente, a 14%, 51%, 4,7% e 7,7% do total precipitado. Nesses compartimentos hidrológicos, de um modo geral, foram observadas baixas concentrações de nitrogênio, com exceção ao escoamento superficial, que apresentou altas concentrações, principalmente de nitrato. O aporte (deposição) de nitrogênio ao sistema, 2,81 kg N ha-¹, foi superior à perda fluvial: 0,45 kg N ha-¹ / The recent years have shown us that there is a perspective of increasing the global biofuels demand, particularly ethanol. In conjunction with the expansion of sugarcane crop, the watersheds in which these crops are founded are subject to hydrological changes, as well as the elevation of the use of nitrogen fertilizers. It has implications in the quantity and quality of water in streams. In order to assess these impacts, the present study aimed to characterize the hydrological flow paths and the associated nitrogen transport in hillslopes under sugarcane in two small watersheds at Corumbataí River, northwest of São Paulo. For this, we monitored some hydrological flow paths, including: gross rainfall, throughfall, stemflow, surface runoff, soil moisture at four depths (15 cm, 30 cm, 50 cm and 90 cm) and streamflow during period of 21 July 2012 to May 22, 2013. Gross rainfall was 1095 mm and around 35% was intercepted by the sugarcane canopy. No significant differences between different varieties of sugarcane were found for interception losses. In addition, rainfall was partitioned into stemflow, throughfall, surface runoff and streamflow as the following: 14%, 51%, 4.7% and 7.7%, respectively. Hydrological flow paths in general carried low nitrogen concentration, being the surface runoff the exception, which carried high levels of nitrate. The nitrogen input in the system was 2.81 kg N ha-¹, and the loss by streamflow was 0.45 kg N ha-1

Submitted by Luciana Ferreira (lucgeral@gmail.com) on 2014-10-03T12:24:01Z No. of bitstreams: 2 Dissertação - Uilton Pereira da Silva Júnior - 2013.pdf: 4441880 bytes, checksum: 0e326268ea8b7a4519657530f34d0fe8 (MD5) license_rdf: 23148 bytes, checksum: 9da0b6dfac957114c6a7714714b86306 (MD5) / Approved for entry into archive by Luciana Ferreira (lucgeral@gmail.com) on 2014-10-06T10:34:13Z (GMT) No. of bitstreams: 2 Dissertação - Uilton Pereira da Silva Júnior - 2013.pdf: 4441880 bytes, checksum: 0e326268ea8b7a4519657530f34d0fe8 (MD5) license_rdf: 23148 bytes, checksum: 9da0b6dfac957114c6a7714714b86306 (MD5) / Made available in DSpace on 2014-10-06T10:34:13Z (GMT). No. of bitstreams: 2 Dissertação - Uilton Pereira da Silva Júnior - 2013.pdf: 4441880 bytes, checksum: 0e326268ea8b7a4519657530f34d0fe8 (MD5) license_rdf: 23148 bytes, checksum: 9da0b6dfac957114c6a7714714b86306 (MD5) Previous issue date: 2013-03-25 / The aim of this work is to study the rainfall partitions in three cultures under different soil managements: soya (Glycine max (L) Merrill) in no-tillage, corn (Zea Mays) in conventional tillage and brachiaria (brachiaria decumbens Stapf cv Comum) in no-tillage. The work was conducted from October 2011 to June 2012. This search was carried on in experimental area of the Federal University of Goias (UFG), campus Jataí, state of Goiás (Brazil). Pluviometers were installed above each culture, on the soil surface, between lines of each culture, in the soil body at 5 cm of soil depth and at 30 cm of soil depth. We used digital and handle pluviometers tools, with 3 (three) repetitions. Aimed calculating the partitions rainfall using datas given by pluviometers installed, based on numbers proposed by Kojac, et al. (2007). Worthed the precipitation intercepted by the canopy (Pf), the direct precipitation (Pd), the flow through the canopy (Ef), retained by the rain canopy (Rf), water saved in the deepth of until 5 cm of soil (Rs5), water saved in the deepth until 30 cm of soil (Rs30), runoff (RO) and the precipitation deep (Pp), over the total precipitation (Pt). To conclusion, the numbers of interceptation and saved by soya, corn and brachiaria canopy were low in negative stage, growing up with the development of foliar areas of farm. In corn culture, approximately 53% of precipitation fall down the soil of target way, in relation to total rain. In soya and brachiaria cases, the most part of rain was intercepted by the canopy before of fall down the soil, with numbers of 81,8% and 54,2% respectively. Understood that, for the three crops, only numbers of rain upper to 3 mm accepted dates of flow through the canopy. Corn presented 0,7% deep precipitation in contrast to total rains and 14% of runoff. The percentage of precipitation and runoff depth for soybeans were 7,2% and 3,7% respectively. To brachiaria was recorded 24% and 2,4% deep precipitation runoff. In tests conducted in the middle stages of vegetative brachiaria and corn, there were significant differences in precipitation retained at a depth of 30 cm soil depth in precipitation and runoff in relation to these crops. In tests conducted in the middle stages of vegetative brachiaria, and corn, there were significant differences in precipitation retained at a depth of 30 cm soil depth in precipitation and runoff. The brachiaria grown in no-till system, showed better water infiltration into the soil and less runoff. Analyzing these dates, it's possible to conclude about importance of maintenance of organic layer in the soil to reduce the runoff and elevating in the percentages of infiltration of soil water. Both the cultivated vegetable species, as the system of land management, were important in determining the values of rainfall partitions. / Este trabalho avalia as partições pluviométricas em três cultivos: soja (Glycine max (L) Merrill) cultivada no sistema de plantio direto, milho (Zea Mays) cultivado no sistema de plantio convencional e pastagem de braquiária (Brachiaria decumbens Stapf cv Comum) cultivada no sistema de plantio direto. O período de estudo foi de outubro de 2011 a junho de 2012. A pesquisa foi conduzida no campo experimental da Universidade Federal de Goiás (UFG), campus Jatobá, no município de Jataí (GO). Foram instalados instrumentos pluviométricos acima de cada cultura, sobre a superfície do solo, a 5 cm de profundidade do solo e a 30 cm de profundidade. Utilizou-se aparelhos pluviométricos manuais e digitais, com 3 repetições. Objetivou-se estimar as partições pluviométricas por meio dos dados fornecidos pelos pluviômetros instalados. Estimou-se a precipitação interceptada pelo dossel (Pf), a precipitação direta (Pd), o escoamento pelo dossel (Ef), a chuva retida pelo dossel (Rf), a água retida na profundidade de até 5 cm do solo (Rs5), a água retida na profundidade de até 30 cm do solo (Rs30), o escoamento superficial (RO) e a precipitação profunda (Pp). Os valores foram estimados em relação à precipitação total (Pt). Concluiu-se que os valores de interceptação e retenção pelo dossel da soja, milho e braquiária foram menores na fase vegetativa, aumentando conforme o desenvolvimento da área foliar dos cultivos. No cultivo do milho, 47% da precipitação foram interceptadas pelo dossel em relação à chuva total. Na soja, 81,8% da chuva foi interceptada pelo dossel antes de atingir o solo, e na braquiária 54,2%. O valor estimado da precipitação retida pelo dossel do milho foi de 28,6%, pelo dossel da soja de 22,7% e pelo dossel da braquiária de 24,7%. Verificou-se que, para os três cultivos, apenas valores de chuvas superiores a 3 mm permitiram registros de escoamento pelo dossel. O milho apresentou 0,7% de precipitação profunda em relação às chuvas totais e 14% de escoamento superficial. Os percentuais de precipitação profunda e escoamento superficial para a soja foram de 7,2% e 3,7% respectivamente. Para a braquiária, foram registrados 24% de precipitação profunda e 2,4% de escoamento superficial. Nos testes de médias realizados nas fases vegetativas da braquiária e do milho, observaram-se diferenças significativas na precipitação retida na profundidade de 30 cm do solo, na precipitação profunda e no escoamento superficial. A braquiária, cultivada no sistema de plantio direto, apresentou maior infiltração de água no solo e menor escoamento superficial em relação ao milho sob plantio convencional. Confirmando, assim, a importância da cobertura vegetal e da manutenção da camada de resíduos orgânicos no solo, para diminuição do escoamento superficial e aumento nas taxas de infiltração de água. Tanto a espécie vegetal quanto o sistema de manejo do solo foram importantes para determinar os valores das partições pluviométricas.

The interception and redirection of rainfall by vegetation has implications for many fields such as remote sensing of soil moisture, satellite observation of rainfall, and the modeling of runoff, climate, and soil erosion. Although the modeling of rainfall partitioning by forests has received attention in the past, partitioning caused by crops has been overlooked. The present work proposes a two front experimental and computational methodology to comprehensively study rainfall interception and partitioning by the maize canopy. In the experimental stage, we deployed two compact weather stations, two optical disdrometers, and five tipping bucket rain gauges. Two of the tipping bucket rain gauges were modified to measure throughfall while two were adapted to measure stemflow. The first optical disdrometer allowed for inspection of the unmodified drop-size and velocity distributions, whereas the second disdrometer measured the corresponding distributions under the canopy. This indicates that the outcome of the interaction between the hydrometeors and the canopy depends on the drop diameter. In the computational stage, we created a model that uses drop-size and velocity distributions as well as a three-dimensional digital canopy to simulate the movement of raindrops on the surfaces of leaves. Our model considers interception, redirection, retention, coalescence, breakup, and re-interception of drops to calculate the stemflow, throughfall, and equivalent height of precipitation stored on plants for a given storm. Moreover, the throughfall results are presented as two-dimensional matrices, where each term corresponds to the accumulated volume of drops that dripped at a given location. This allows insight into the spatial distribution of throughfall beneath the foliage. Finally, we examine the way in which the maize canopy modifies the drop-size distribution by recalculating the drop velocity based on the raindrop's size and detachment height and by storing the counts of drops in diameter-velocity classes that are consistent with the classes used by disdrometers in the experimental study.

This research examined the mechanisms by which temperature, water availability and nitrogen (N) affect the dry matter (DM) yield potential of cocksfoot (Dactylis glomerata L.) dominant pastures. The experiment was a split plot design with main plots of fully irrigated (I) or dryland (D), sub-plots of N fertiliser at 800 kg N/ha in 2003/04; and 1600 kg N/ha in 2004/05 (+N) or 0 kg N/ha (-N). The potential environmental yield of an established 8 year old cocksfoot dominant pasture was 21.9 t DM/ha/y from I+N pastures compared with 9.8 t DM/ha by I-N pastures and 15.1 t DM/ha/y by D+N pastures. The lowest yields were from dryland pastures with no N which produced 7.5 t DM/ha/y in 2003/03 and 5.0 t DM/ha/y in 2004/05. The effect of seasonal temperatures on the DM production, when periods of water stress were excluded, was quantified using thermal time accumulated above a base temperature of 3°C as 7.0 kg DM/°Cd/ha for N fertilised pastures and 3.3 kg DM/°Cd/ha for pastures with no N. The 2.5 t DM/ha difference in yields of D-N pastures in 2003/04 and 2004/05 was the result of the duration, extent and timing of the water stress period. In both years the critical limiting deficit (DL) was calculated as 78 mm from the soil moisture deficit in the 0-0.8 m soil layers. Beyond DL yield decreased at a rate of 1.45%/mm in +N and –N pastures, relative to fully irrigated control pastures. Yields of D+N and D-N pastures were similar during periods of water stress with 0.4±0.1 t/DM/ha produced during the rotation ending 30/12/2003. This was less than from either the I-N (1.2 t DM/ha) or I+N (3.5 t DM/ha) pastures due to the reduction in the amount of photosynthetically active radiation intercepted by the canopies of the dryland pastures. However, in the rotation ending 2/5/2004, after autumn rain alleviated drought conditions, yield of the D+N pasture was 2.1 t DM/ha compared with 1.7 t DM/ha by I+N pastures. The effect of N on yield was described using a nutrition index which showed that as DM yield increased N% in the herbage declined. This is a function of the ratio between metabolic and structural N requirements rather than caused by ontogeny alone. Specific leaf N was determined at two harvests and appeared constant at a given point in time (1.0-1.6 g N/m² leaf). In contrast, specific pseudostem N increased from 0.8-1.0 g N/m² pseudostem at an NNI of 0.4 in –N pastures to 2.6-3.0 g N/m² pseudostem at an NNI of 1.2 in the +N pastures. Differences between the yields of +N and –N pastures were caused by differences in radiation use efficiency (RUE) as determined by the linear relationship (R²=0.76) between RUE and the nitrogen nutrition index (NNI). In this thesis, empirical relationships for the effects of temperature, water availability and N were derived and the physiological mechanisms which underlie these descriptions were identified. These relationships provide clear and simple explanations of the effects of environmental variables on the productivity of cocksfoot based pastures which will enhance understanding of the benefits and limitations of cocksfoot, particularly in dryland farming systems.

Peatlands are carbon sinks and occupy approximately 13% of Canada’s terrestrial surface of which 0.02% have been harvested for horticultural peat. The extraction of peat from natural peatlands alters the hydrology which affects the growth and survival of Sphagnum the primary peat forming vegetation. Ericaceous shrubs do not require specific water content and soil water pressure conditions for their existence and in cutover peatlands they occupy more than 70% of the surface. Rainfall interception, transpiration and root water uptake and redistribution are processes that alter water availability at the soil surface. The high abundance of shrubs at cutover peatlands will influence the surface water balance and more importantly soil water availability and, inevitably determine the success of Sphagnum reestablishment at the site. This study seeks to understand the role that ericaceous shrubs play in the surface hydrological balance at a cutover site and how these changes impact Sphagnum development. Rainfall interception, transpiration, litter layer evaporation and soil water flux was investigated in the field and lab. Approximately 334 mm of rainfall was measured over the season. The shrub canopy and litter had a maximum storage capacity of 4 and 1.2 mm respectively and intercepted ca. 36.7% (120 mm) of rainfall over the season. The effects of rainfall intensity and duration were more important than gross rainfall in determining the amount of water intercepted by the canopy, while the thickness and mass of the litter layer largely determined the storage capacity. Evapotranspiration from shrubs averaged 2.5 mm day-1 with a total of 211 mm over the season. Transpiration was 68% (142 mm) of total evapotranspiration losses, and represented the greatest water loss from the shrub canopy. From these analyses only 22% (72 mm) of rainfall is available for other soil processes and moss development. The evaporation under a litter cover is lower than bare peat and in the field represents water storage of 17 mm over the season. Reduced water input by litter interception is offset by the increased water storage under the litter. Laboratory analyses of soil water flux under ericaceous shrubs show that water loss under the shrubs was greater than bare peat. Water use under the shrubs was highest between -10 and -30 cm and was ca. 2 times greater than bare peat at the same levels. Volumetric water content (θ) decreased throughout the day and water use by shrubs during the day was twice that at night. The shrubs also maintained θ and soil water pressure (ψ) above the threshold values of 50% and -100 cm, respectively, needed for Sphagnum survival. Based on these analyses the shrubs will be beneficial to Sphagnum reestablishment and survival once the primary water losses have been compensated. I recommend raising the water table above -20 cm. In peatland restoration activities, at this level, water used between -10 and -30 cm can quickly be recharged and surface moisture maintained above threshold by capillary rise helping to offset water loss by interception and transpiration through capillary rise.

Peatlands are carbon sinks and occupy approximately 13% of Canada’s terrestrial surface of which 0.02% have been harvested for horticultural peat. The extraction of peat from natural peatlands alters the hydrology which affects the growth and survival of Sphagnum the primary peat forming vegetation. Ericaceous shrubs do not require specific water content and soil water pressure conditions for their existence and in cutover peatlands they occupy more than 70% of the surface. Rainfall interception, transpiration and root water uptake and redistribution are processes that alter water availability at the soil surface. The high abundance of shrubs at cutover peatlands will influence the surface water balance and more importantly soil water availability and, inevitably determine the success of Sphagnum reestablishment at the site. This study seeks to understand the role that ericaceous shrubs play in the surface hydrological balance at a cutover site and how these changes impact Sphagnum development. Rainfall interception, transpiration, litter layer evaporation and soil water flux was investigated in the field and lab. Approximately 334 mm of rainfall was measured over the season. The shrub canopy and litter had a maximum storage capacity of 4 and 1.2 mm respectively and intercepted ca. 36.7% (120 mm) of rainfall over the season. The effects of rainfall intensity and duration were more important than gross rainfall in determining the amount of water intercepted by the canopy, while the thickness and mass of the litter layer largely determined the storage capacity. Evapotranspiration from shrubs averaged 2.5 mm day-1 with a total of 211 mm over the season. Transpiration was 68% (142 mm) of total evapotranspiration losses, and represented the greatest water loss from the shrub canopy. From these analyses only 22% (72 mm) of rainfall is available for other soil processes and moss development. The evaporation under a litter cover is lower than bare peat and in the field represents water storage of 17 mm over the season. Reduced water input by litter interception is offset by the increased water storage under the litter. Laboratory analyses of soil water flux under ericaceous shrubs show that water loss under the shrubs was greater than bare peat. Water use under the shrubs was highest between -10 and -30 cm and was ca. 2 times greater than bare peat at the same levels. Volumetric water content (θ) decreased throughout the day and water use by shrubs during the day was twice that at night. The shrubs also maintained θ and soil water pressure (ψ) above the threshold values of 50% and -100 cm, respectively, needed for Sphagnum survival. Based on these analyses the shrubs will be beneficial to Sphagnum reestablishment and survival once the primary water losses have been compensated. I recommend raising the water table above -20 cm. In peatland restoration activities, at this level, water used between -10 and -30 cm can quickly be recharged and surface moisture maintained above threshold by capillary rise helping to offset water loss by interception and transpiration through capillary rise.

<p>Software vulnerabilities in programs and malware deployments have been increasing almost every year since we started measuring them. Information about how to program securely, how malware shall be avoided and technological countermeasures for this are more available than ever. Still, the trend seems to favor the attacker. This thesis tries to visualize the effects of a selection of technological countermeasures that have been proposed by researchers. These countermeasures: non-executable memory, address randomization, system call interception and file integrity monitoring are described along with the attacks they are designed to defend against. The coverage of each countermeasure is then visualized with the help of attack trees. Attack trees are normally used for describing how systems can be attacked but here they instead serve the purpose of showing where in an attack a countermeasure takes effect. Using attack trees for this highlights a couple of important aspects of a security mechanism, such as how early in an attack it is effective and which variants of an attack it potentially defends against. This is done by the use of what we call defensive codes that describe how a defense mechanism counters a sub-goal in an attack. Unfortunately the whole process is not well formalized and depends on many uncertain factors.</p>