Submitted by Emanuel Varela Cardoso (emanuel.varela@ufcg.edu.br) on 2018-08-14T18:32:14Z No. of bitstreams: 1 ALEXANDRE MAGNO TEODOSIO DE MEDEIROS – TESE (PPGMet) 2017.pdf: 15829653 bytes, checksum: e3488ce83a714300069849345ca5f676 (MD5) / Made available in DSpace on 2018-08-14T18:32:14Z (GMT). No. of bitstreams: 1 ALEXANDRE MAGNO TEODOSIO DE MEDEIROS – TESE (PPGMet) 2017.pdf: 15829653 bytes, checksum: e3488ce83a714300069849345ca5f676 (MD5) Previous issue date: 2017-02-22 / O objetivo deste trabalho foi desenvolver uma nova abordagem metodológica para ser utilizada em associação aos resultados da técnica já consolidada do Zoneamento Agrícola de Riscos Climáticos (ZARC) adotada pelo Ministério da Agricultura, Pecuária e Abastecimento - MAPA, visando adequar os resultados do zoneamento tradicional a realidade do período chuvoso local, através da análise do balanço hídrico, procurando assim, minimizar, ainda mais o risco climático para a cultura do milho de sequeiro no Estado da Paraíba. Elaborou-se inicialmente o ZARC para a cultura do milho, com base na aplicação do modelo de balanço hídrico SARRAZON (Sistema de Análise Regional dos Riscos Agroclimáticos, Módulo Zoneamento) e que combinado com ferramentas de geoprocessamento, utilizou-se para identificar as áreas e os períodos de menor risco de quebra de rendimento e restrições hídricas. O índice de Satisfação da Necessidade de Água (ISNA) foi adotado com o critério de corte e definido como a relação entre a evapotranspiração real e a evapotranspiração máxima (ETR/ETM) para valores entre 0,45 e 0,55, que definira uma aptidão agrícola. Foram utilizados dados de precipitação pluviométrica do período de 1961 a 2012 e dados de temperatura estimada, de 99 pontos no Estado da Paraíba, parâmetros do solo e da cultura do milho (capacidade de água disponível, duração dos ciclos e das fases fenológicas, coeficientes de cultura, etc) e que associados aos resultados do ISNA e às classes de riscos, foram utilizados para a geração dos resultados finais do zoneamento. Os resultados obtidos foram utilizados para delimitar as regiões com maior potencial agroclimático e determinar as épocas de semeadura que ofereçam menores riscos climáticos, assim, foi possível identificar as melhores datas de plantio, minimizando os riscos climáticos regionais. Por outro lado, desenvolveu-se uma nova abordagem metodológica, chamada de Zoneamento Climático Ajustado (ZOCLIMA), que baseada no balanço hídrico sequencial de Thornthwaite&Mather foi determinado os períodos de excedente, deficiência e reposição, e como os resultados gráficos do balanço, delimitou-se a área da reposição hídrica com a interseção do zero do período de excedente hídrico, criando um período delimitado e que foi considerado como a faixa temporal mais adequada à semeadura. Esse resultado foi utilizado como complementar e restritivo ao SARRAZON, filtrando as épocas de plantio já definidas como indicado pelo ZOCLIMA, gerando assim um novo calendário indicativo do plantio do milho de sequeiro. O ZOCLIMA, apesar de ser mais restritivo, conseguiu filtrar os extremos extrapolantes dos resultados obtidos pelo SARRAZON, que indicava datas de plantio fora do período mais chuvoso da região, tanto no início, quanto no final da estação chuvosa e com isso reduziu o risco climático da perda ou quebra de safra do milho de sequeiro, principalmente por apresentar um período limitante mais seguro e a garantia de indicativo climatológico de umidade no solo e de também poder aplicar a metodologia individualmente para cada localidade, garantindo assim, um indicativo do período de semeadura dentro do período mais chuvoso de cada região, reduzindo deste modo, as perdas por estresse hídrico. / The main objective of this study was to develop a new methodological approach to be used in association with the results of the already consolidated technique of Agricultural Zoning of Climate Risks (ZARC) adopted by the Ministry of Agriculture, Livestock and Food Supply MAPA, aiming to adapt the results of the traditional zoning to regional rainy season through the analysis of the local water balance, trying to minimize even more the climatic risk for the corn crop in the state of Paraíba. The ZARC was initially developed for the maize crop, based on the application of the SARRAZON (System of Regional Analysis of Agroclimatic Risks, Zoning Module) water balance model and, combined with geoprocessing tools, was used to identify the areas and periods with the lowest risk of yield loss and water restrictions. The Water Need Satisfaction Index (ISNA) was adapted as a cutoff criterion and was defined as there lation between actual evapotranspiration and maximum evapotranspiration (ETR/ETM) for values between 0.45 and 0.55, which defined the fitness agricultural. Rainfall data from 1961 to 2012 and estimated temperature data for 99 points in the State of Paraíba, soil and maize parameters (available water capacity, duration of cycles and phonological phases, coefficients of culture, etc.) and associated with ISNA results and risk classes, were used to generate the final zoning results. There sults obtained were used to delineate the regions with the greatest agroclimatic potential and to determine the so wing times that offer lower climatic risks, thus, it was possible to identify the best planting dates, minimizing the regional climatic risks. On the other hand, a new methodological approach was developed, called Adjusted Climatic Zoning (ZOCLIMA), which based on the Thornthwaite & Mather sequential water balance was determined the periods of surplus, deficiency and replacement, and the graphical results of the balance sheet, the area of the water replenishment was delimited with the Intersection of zero of the water surplus period, creating a delimited period and that was considered as the most suitable temporal range to so wing. This result was used as complementary and restrictive to SARRAZON, filtering the planting times already defined with the indicated by ZOCLIMA, generating a new indicative calendar of the plantation of the drycorn. ZOCLIMA, although more restrictive, was able to filter the extra polating extremes of the results obtained by SARRAZON, which indicated dates of planting outside the rainy season in the region, both at the beginning and at the end of the rainy season, reducing the climatic risk of the loss or crop failure of rainfed maize, mainly because it presents a more secure limiting period and the guarantee of a climatologic indication of humidity in the soil and also to be able to apply the methodology individually for each locality, thus guaranteeing an indicative of the so wing period within the wettest period of each region, thus reducing water stress losses.

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / The sustainability of the crop production, i.e. the ability to remain itself in the market, protecting the environment and have good financial returns is often threatened by risk factors. Among the risk factors in agriculture, highlights the climatic factor, and hail occurrence of extreme events of this factor. The objective of this study was to evaluate sunflower plants responses after application of different levels of injury in leaves in different phenological stages, to quantify the injury effect on the productivity reduction of achenes. In addition, mathematical models were developed to estimate the production reduction in function of crop development stage and occurrence intensity of injury in leaves. The experiments were conducted at Crop Science Department of the Federal University of Santa Maria, Santa Maria, RS, Brazil, in the agricultural years 2009/2010 and 2010/2011, following the growth and development of plants during the crop cycle through phenological and phenometric observations. The meteorological data were obtained from the meteorological station of Santa Maria, belonging to 8th DISME/INMET/MA. Were made sixteen treatments arranged in a randomized block design with three replications for the 2009/2010 agricultural year and fifteen treatments for the 2010/2011 agricultural year. The treatments consisted of four foliar injury levels (0, 25, 50 and 75%) applied at four phenological stages (20 emitted leaves, R2, R5.1 and R6) of sunflower plants in the experiment conducted in 2009/2010 and five foliar injury levels (0, 25, 50, 75 and 100%) applied at three phenological stages (20 emitted leaves, R2 and R6) of sunflower plants in 2010/2011. The injuries were promoted by perforations in leaf blade of all sunflower leaves with auger of 23, 25 and 30 mm in diameter. The number of perforations was set according of leaves width, auger diameter and desired injury level. The sunflower yield was affected by injury levels applied and by stages considered. The reproductive stage R2 was most affected by injuries, while 25% injury level had caused proportionally greater effect on sunflower yield. / A sustentabilidade da produção de uma cultura, isto é, a capacidade desta conservar-se no mercado, preservar o ambiente e ter bons retornos financeiros é frequentemente ameaçada por fatores de risco. Dentre os fatores de risco na agricultura, destaca-se o fator climático, e a ocorrência de granizo é um dos eventos extremos deste fator. O objetivo deste trabalho foi avaliar as respostas das plantas de girassol após a aplicação de diferentes níveis de injúria foliar, em diferentes estágios fenológicos, para quantificar o efeito dessa injúria na redução da produtividade de aquênios. Além disso, objetivou-se desenvolver modelos matemáticos de estimativa de redução de produção em função do estágio de desenvolvimento da cultura e da intensidade da ocorrência da injúria foliar. Os experimentos foram conduzidos junto ao Departamento de Fitotecnia da Universidade Federal de Santa Maria, Santa Maria, nos anos agrícolas de 2009/2010 e 2010/2011, acompanhando-se o crescimento e o desenvolvimento das plantas no decorrer do ciclo da cultura através de observações fenométricas e fenológicas. Os dados meteorológicos foram obtidos junto à estação meteorológica principal de Santa Maria, pertencente ao 8° DISME/INMET/MA. Foram realizados dezesseis tratamentos arranjados no delineamento de blocos ao acaso, com três repetições para o ano agrícola 2009/2010 e quinze tratamentos para o ano agrícola de 2010/2011. Os tratamentos constaram de quatro níveis de injúria foliar (0, 25, 50 e 75%) aplicados em quatro estágios fenológicos (20 folhas emitidas, R2, R5.1 e R6) das plantas de girassol para experimento conduzido em 2009/2010 e cinco níveis de injúria foliar (0, 25, 50, 75 e 100%) aplicados em três estágios fenológicos (20 folhas emitidas, R2 e R6) das plantas de girassol em 2010/2011. As injúrias foram promovidas por meio de perfurações no limbo foliar de todas as folhas das plantas de girassol realizadas com o auxílio de vazadores de 23, 25 e 30 mm de diâmetro. O número de perfurações era estipulado de acordo com a largura das folhas, diâmetro do vazador e nível de injúria pretendido. A produtividade do girassol foi afetada pelos níveis de injúria aplicados e pelos estágios considerados. O estágio reprodutivo R2 foi o mais afetado pelas injúrias, enquanto que a injúria de 25% foi a que promoveu proporcionalmente maior efeito na produtividade do girassol.

Diese kumulative Dissertation untersucht in drei Kapiteln den Effekt von Risiko auf Firmenentscheidungen und die Fähigkeit von Firmen, Risiken mit ihren Stakeholdern zu teilen. Die betrachteten Firmen sind Skihotels in österreichischen Skigebieten. Das erste Kapitel ist eine umfassende Studie zur Risikoteilung zwischen Skihotels und ihren Stakeholdern. Es gibt zwei hauptsächliche Ergebnisse. Erstens wird gezeigt, dass Unternehmer Wetterrisiko mit ihren Arbeitnehmern teilen, selbst aber kein Wetterrisiko tragen. Dieses Ergebnis ist in Widerspruch zur Vorstellung des Unternehmers als Risikoträger. Das zweite Ergebnis ist, dass Firmen Wetterrisiko mit ihrer Hausbank teilen. Das zweite Kapitel untersucht anhand von Banken in österreichischen Skigebieten die Rolle des Interbankenmarkt. Die Banken in Skigebieten sind Liquiditätsschocks ausgesetzt, die durch touristisch bedingte Nachfrageschocks erzeugt werden. Der Effekt dieser Schocks auf die Kredittätigkeit ist Gegenstand dieser Studie. Das Ergebnis der Studie ist, dass Banken mehr Kapital auf dem Interbankenmarkt beschaffen, wenn sie ihren Kunden in der Realwirtschaft in Folge eines Nachfrageschocks Liquidität gewähren müssen. Das dritte Kapitel untersucht, wie die Beschäftigung von kleinen Firmen auf Risiko in der Arbeitsproduktivität reagiert. Ein Ergebnis ist, dass das abhängig ist von der Kapitalisierung des lokalen Bankenmarktes. Es wird gezeigt, dass eine Zunahme in transitiven Arbeitsproduktivitätsrisiko die Bereitschaft der Firmen verringert Arbeitnehmer einzustellen. Dieser Effekt ist umso stärker, je schlechter lokale Banken kapitalisiert sind. Es scheint, als würde ein Mangel an Kapital in Bankensektor die Fähigkeit von Skihotels mindern, Arbeitsproduktivität einzugehen. / This thesis contains three chapters that empirically study the impact of risk on firm level decisions and firms’ ability to share risks with their stakeholders. The firms that are studied in all three papers are hotels in Austrian ski resorts. The first chapter provides a comprehensive study of the risk sharing between Austrian ski hotels and their stakeholders. We obtain two main results. The first main finding is that the entrepreneurs share snow-induced sales risk with their workers, while the dividend payments to the entrepreneurs are not affected by these exogenous shocks to firms’ sales. This finding opposes the view of the entrepreneur as a risk taker. We find that hotels insure their workers against weather-induced sales shocks only if the shocks are highly temporary during the winter-season. The second main result is that entrepreneurs share exogenous sales risk with their house-banks. The second chapter empirically analyzes interbank lending using a sample of banks in Austrian ski resorts. The banks are subject to liquidity shocks due to weather-induced demand shocks in ski tourism. We analyze the effect of these shocks on interbank lending and borrowing. In our analysis, we use snow in ski resorts as an instrumental variable for the possibly endogenous demand shocks. The analysis reveals that banks reduce their net lending to other banks at times when they need to provide liquidity to their non-bank customers. The third chapter empirically studies how small-firm employment respond to labor productivity risk. We show that this depends on the equity capital of local banks. We find that an increase in the risk of transitory productivity shocks reduces firms’ willingness to commit to employing workers. This effect is stronger if local banks have less equity capital. It appears that a lack of bank equity reduces firms’ capacity to take labor productivity risk.

The agriculture sectors in Canada are highly vulnerable to a wide range of inter-related weather risks linked to seasonal climate variability (e.g., El Ni ̃no Southern Oscillation(ENSO)), short-term extreme weather events (e.g., heatwaves), and emergent disease(e.g., grape powdery mildew). All of these weather-related risks can cause severe crop losses to agricultural crop yield and crop quality as Canada grows a wide range of farm products, and the changing weather conditions mainly drive farming practices. This dissertation presents three machine learning-based statistical models to assess the weather risks on the Canadian agriculture regions and to provide reliable risk forecasting to improve the decision-making of Canadian agricultural producers in farming practices. The first study presents a multi-scale, cluster-based Principal Component Analysis(PCA) approach to assess the potential seasonal impacts of ENSO to spring wheat and barley on agricultural census regions across the Canada prairies areas. Model prediction skills for annual wheat and barley yield have examined in multi-scale from spatial cluster approaches. The ’best’ spatial models were used to define spatial patterns of ENSO forcing on wheat and barley yields. The model comparison of our spatial model to non-spatial models shows spatial clustering and ENSO forcing have increase model performance of prediction skills in forecasting future cereal crop production. The second study presents a copula-Bayesian network approach to assess the impact of extreme high-temperature events (heatwave events) on the developments of regional crops across the Canada agricultural regions at the eco-district-scale. Relevantweather variables and heatwave variables during heatwave periods have identified and used as input variables for model learning. Both a copula-Bayesian network and Gaussian-based network modeling approach is evaluated and inter-compared. The copula approach based on ’vine copulas’ generated the most accurate predictions of heatwave occurrence as a driver of crop heat stress. The last study presents a stochastic, hybrid-Bayesian machine-learning approach to explore the complex causal relationships between weather, pathogen, and host for grape powdery mildew in an experimental farm in Quebec, Canada. This study explores a high-performance network model for daily disease risk forecast by using estimated development factors of pathogen and host from recorded daily weather variables. A fungicide strategy for disease control has presented by using the model outputs and forecasted future weather variability. The dissertation findings are beneficial to Canada’s agricultural sector. The inter-related weather risks explored by the three separate studies in multi-scales provide a better understanding of the interactions between changing weather conditions, extreme weather, and crop production. The research showcases new insights, methods, and tools for minimizing risk in agricultural decision-making / Graduate / 2021-08-19

Sveriges fastighetssektor står inför betydande utmaningar på grund av pågående och förväntade klimatförändringar. För att nämna några få av de klimatfaktorer som påverkar fastigheters värde och sårbarhet kan vi idag se början på temperaturökningar, förändrade nederbördsmönster, stigande havsnivåer och ökad frekvens av extremväder. Dessa klimatrelaterade risker kan leda till fysiska skador på fastigheter, ökade driftskostnader samt påverka investeringsbeslut. Den stora frågan är dock hur vi ska bemöta dessa risker när det kommer till fastigheter, samt hur stor påverkan de har på fastigheternas värde. Klimatfrågan har allt eftersom blivit mer central när det kommer till fastighetsvärdering i Sverige idag. Detta i takt med att riktlinjer har tagits fram av EU samt diverse nationella initiativ som främjar hållbarhet och klimatanpassning. Bland dessa exempel på hur lagstiftningen utvecklas för att möta klimatutmaningarna är bland annat EU:s taxonomi för hållbara investeringar samt den svenska regeringens propositioner om ökad transparens och rapporteringskrav för företag. Denna studie syftar till att undersöka om klimatriskanalyser av fastigheter bidrar till förändringar i fastighetsvärdet, särskilt när analysen visar på risk för påverkan från klimatrisker. Studien avser att klargöra i vilken utsträckning klimatrisker beaktas i fastighetsvärderingar och hur dessa risker påverkar marknadsvärdet och investeringsbeslutidag, samt hur detta kan komma att förändras i framtiden.  Studien bygger på tidigare forskning från andra länder samt intervjuer med fastighetsvärderare, experter inom klimatrisksanalyser och fastighetsinvesterare i Sverige. Genom att kombinera internationella erfarenheter och insikter från svenska experter syftar studien till att belysa hur klimatrisker för närvarande hanteras inom fastighetsbranschen i Sverige och hur dessa analyser påverkar värderingsprocesser och investeringsbeslut framöver. Resultaten förväntas ge insikt i hur svenska fastighetsaktörer hanterar klimatrisker och bidra till utvecklingen av mer hållbara och motståndskraftiga fastighetsvärderingsmetoder. / Sweden's real estate sector faces significant challenges due to ongoing and anticipated climate changes. Some of the climate factors affecting property values and vulnerability today include temperature increases, altered precipitation patterns, rising sea levels, and an increased frequency of extreme weather events. These climate-related risks can lead to physical damage to properties, increased operational costs, and influence investment decisions. The critical question is how to address these risks concerning real estate and the extent of their impact on property values. The climate issue has increasingly become central to property valuation in Sweden today. This is in line with guidelines developed by the EU and various national initiatives promoting sustainability and climate adaptation. Examples of how legislation is evolving to meet climate challenges include the EU taxonomy for sustainable investments and the Swedish government's propositions on increased transparency and reporting requirements for companies. This study aims to investigate whether climate risk assessments of properties contribute to changes in property values, particularly when the analysis indicates a risk of impact from climate risks. The study intends to clarify to what extent climate risks are considered in property valuations, how these risks affect market value and investment decisions today, and how this might change in the future. The study is based on previous research from other countries and interviews with property appraisers, experts in climate risk analysis and property investors in Sweden. By combining international experiences and insights from Swedish experts, the study aims to highlight how climate risks are currently managed within the real estate sector in Sweden and how these assessments impact valuation processes and investment decisions moving forward. The results are expected to provide insights into how Swedish real estate stakeholders handle climate risks and contribute to the development of more sustainable and resilient property valuation methods.

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / The approach to knowledge about the probabilities of water excess occurrence enables the planning sunflower crop management, mainly about the sowing period. The objective of this study was quantify and analyze the occurrence of water excess through numerical study for sunflower crop sown on different dates, considering the storage capacity of water in different soils of the Central Region of Rio Grande do Sul and determine the probability distribution functions that better represent the water excess occurrence. Mathematical modeling was used to simulate the sunflower development, considering a medium maturity genotype. The simulation was done for 14 sowing dates in each year of the time series of 43 years of diary weather data from 1968 to 2011 of Main Climatological Station of Santa Maria (ECPSM). The number of days with water excess in different development stages of culture was determined for main soils of the region covered by the ECPSM. Capacity values of available water storage (CAD) were considered according soil and culture characteristics, being the water excess calculated using the Dialy Water Balance, represented by accumulated water in the soil exceeding the CAD. The distribution probability functions tested for the number of days with water excess were Normal, Exponential, Gamma, Lognormal and Weibull, and the Kolmogorov-Smirnov and Chi-square tests were used to check the fit of functions. The weather conditions were different for the different sowing dates simulated in 43 years, so that differentiate the simulations of the development cycle of the sunflower. Thus, difference was observed in the number of days with water excess between sowing dates for all sub-periods analyzed. In terms of functions, there was at least one function that is fitted in most of the cases, and when there was no possible fit, the empirical frequency was used to analyze the risk. The Weibull had the greatest number of adjustments for developmental cycle as well as for subperiods. Early August until mid-September sowing dates are those with the greatest number of days with water excess, considering the whole development cycle of sunflower, regardless of the soil CAD. / A abordagem do conhecimento acerca das probabilidades de ocorrência de excedentes hídricos permite o planejamento do manejo da cultura do girassol, principalmente quanto ao período de semeadura. O objetivo do presente trabalho foi quantificar e analisar a ocorrência de excesso hídrico, por meio de estudo numérico, para a cultura do girassol semeada em diferentes datas, considerando-se a capacidade de armazenamento de água nos diferentes solos da região central do Rio Grande do Sul e determinar as funções de distribuição de probabilidade que melhor representam a ocorrência de excesso hídrico. Foi utilizada a modelagem matemática para simular o desenvolvimento da cultura do girassol, considerandose um genótipo de grupo de maturidade médio, sendo a simulação feita para 14 datas de semeadura em cada ano da série histórica de 43 anos de dados meteorológicos da Estação Climatológica Principal de Santa Maria (ECPSM), desde 1968 até 2011. A ocorrência de dias com excesso hídrico nos diferentes subperíodos da cultura foi determinada para os principais solos da região de abrangência da ECPSM. Foram considerados os valores de capacidade de armazenamento de água disponível (CAD) conforme características dos solos e da cultura, sendo o excesso hídrico calculado por meio do Balanço Hídrico Sequencial Diário, representado pelo acumulado de água no solo excedente à CAD. As funções de distribuição de probabilidade testadas para o número de dias com excesso hídrico foram Normal, Exponencial, Gama, Lognormal e Weibull, sendo utilizados os teste de Kolmogorov-Smirnov e Chi-Quadrado para verificar o ajuste das funções. As condições meteorológicas foram distintas para as diferentes datas de semeadura simuladas nos 43 anos, de modo a diferenciar as simulações do ciclo de desenvolvimento do girassol. Assim, houve diferença no número de dias com excesso hídrico entre as datas de semeadura para todos os subperíodos analisados. Em relação às funções, houve pelo menos uma função que se ajustou na maioria dos casos, sendo que quando não houve ajuste possível foi utilizada a frequência empírica para analisar o risco. A função Weibull apresentou maior número de ajustes, tanto para o ciclo de desenvolvimento quanto para os subperíodos. As datas de semeadura de início de agosto até meados de setembro são as que apresentam a maior ocorrência de dias com excesso hídrico, considerando todo o ciclo de desenvolvimento do girassol, independente da CAD do solo.

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / The expansion of soybean production area in Planosols is rather limited by the high frequency of occurrence of excess water, leading to reduced availability of oxygen in the root zone, reduced photosynthesis, as well as productivity, depending on its duration and developmental phase of plants it occurs. The aim of this study was to identify sowing dates with smaller risk of excess water to the subperiods and crop cycle, taking into account three relative maturity groups of soybean cultivars and water storage capacity of Planosols in the central region of Rio Grande do Sul State. The simulation of soybean development and the calculation of crop daily sequential water balance were performed at different sowing dates in each year from August 1968 to July 2012. Thus, the change of soil water storage and the water surpluses in the different soybean developmental phases were quantified for each sowing date. Data from days with excess water were submitted to analysis of variance and Scott-Knott test at 5% probability, and the sources of variation were sowing dates, soils and their interaction. These data also were submitted to the probability distribution analysis, using the chi-square and Kolmogorov-Smirnov tests to verify the probability density function that best fit the data distribution. The greatest number of fittings for the development cycle and subperiods were obtained by the Gamma and Weibull functions, respectively. October's sowings have the highest risk of excess water during the crop cycle. Subperiod sowing-emergence shows up as the most limiting to define the sowing date. Due to the lowest risk of excess water in this sub-period, the sowing carried out after November 1st are the most favorable for soybean sowing in Planosols. / A expansão da área de produção de soja em Planossolos é bastante limitada pela elevada frequência de ocorrência de excesso hídrico, ocasionando redução na disponibilidade de oxigênio na zona radicular, redução da fotossíntese, assim como da produtividade, dependendo da duração do excesso e do subperíodo de desenvolvimento das plantas em que ocorre. O objetivo deste trabalho foi identificar datas de semeadura com menor risco de ocorrência de excesso hídrico para os subperíodos e ciclo da cultura, considerando três grupos de maturidade relativa de cultivares de soja e a capacidade de armazenamento de água dos Planossolos da região central do Rio Grande do Sul. A simulação do desenvolvimento da soja e o cálculo do balanço hídrico sequencial diário da cultura foram realizados em diferentes datas de semeadura de cada ano do período de agosto de 1968 a julho de 2012. Assim, a variação do armazenamento hídrico no solo e a ocorrência de excedentes hídricos nos diferentes subperíodos de desenvolvimento da soja foram quantificadas para cada data de semeadura. Os dados de dias de excesso hídrico foram submetidos à análise de variância e teste de Scott-Knott, a 5% de probabilidade de erro, sendo que as fontes de variação constaram das datas de semeadura, os solos e a sua interação. Os dados também foram submetidos à análise de distribuição de probabilidades, utilizando-se os testes qui-quadrado e Kolmogorov-Smirnov para verificar a função densidade probabilidade que melhor se ajustou à distribuição dos dados. O maior número de ajustes para o ciclo de desenvolvimento e para os subperíodos foram obtidos para as funções gama e weibull, respectivamente. As semeaduras realizadas no mês de outubro são as de maior risco de ocorrência de excesso hídrico ao longo do ciclo da cultura. O subperíodo semeadura-emergência mostra-se como o mais limitante para a definição da data de semeadura. Devido ao menor risco de ocorrência de excesso hídrico neste subperíodo as semeaduras realizadas após o dia primeiro de novembro são as mais favoráveis para a semeadura da soja em Planossolos.

Die Anzahl der unterernährten Menschen in der Welt steigt seit 2017 wieder an. Der Klimawandel wird den Druck auf die Landwirtschaft und die Ernährungssicherheit weiter erhöhen, insbesondere für kleinbäuerliche und von Subsistenzwirtschaft geprägte Agrarsysteme in den Tropen. Um die Widerstandsfähigkeit der Ernährungssysteme und die Ernährungssicherheit zu stärken, bedarf es eines Klimarisikomanagements und Klimaanpassung. Dies kann sowohl die Antizipation als auch die Reaktion auf die Auswirkungen der globalen Erwärmung ermöglichen. Eine zentrale Rolle spielen in dieser Hinsicht landwirtschaftliche Modelle. Sie können die Reaktionen von Pflanzen auf Veränderungen in den Klimabedingungen quantifizieren und damit Risiken identifizieren. Diese Dissertation demonstriert anhand dreier in Peru, in Tansania und in Burkina Faso durchgeführten Fallstudien, wie statistische Ertragsmodelle das Klimarisikomanagement und die Anpassung in der tropischen Landwirtschaft unterstützen können. Während die erste Studie zeigt, wie Klimaanpassungsbestrebungen unterstützt werden können, werden in Studie zwei und drei statistische Modelle genutzt, um Ertrags- und Produktionsvorhersagen zu erstellen. Die Ergebnisse können dazu beitragen, Frühwarnsysteme für Ernährungsunsicherheit zu unterstützen. In den drei Veröffentlichungen werden neue Ansätze statistischer Ertragsmodellierung auf verschiedenen räumlichen Ebenen vorgestellt. Ein besonderer Fokus liegt hierbei auf der Weiterentwicklung von bisherigen Ertragsvorhersagen, insbesondere in Bezug auf unabhängige Modellvalidierungen, eine stärkere Berücksichtigung von Wetterextremen und die Übertragbarkeit der Modelle auf andere Regionen. / The number of undernourished people in the world has been increasing since 2017. Climate change will further exacerbate pressure on agriculture and food security, particularly for smallholder and subsistence-based farming systems in the tropics. Anticipating and responding to global warming through climate risk management is needed to increase the resilience of food systems and food security. Crop models play an indispensable role in this regard. They allow quantifying crop responses to changes in climatic conditions and thus identify risks. This dissertation demonstrates how statistical crop modelling can inform climate risk management and adaptation in tropical agriculture in the case studies of Peru, Tanzania and Burkina Faso. While the first study shows how statistical crop models can support climate adaptation, studies two and three provide yield and production forecasts. The results can contribute to supporting early warning systems on food insecurity. The three publications present novel approaches of statistical yield modelling at different spatial scales. A particular focus is on further developing existing yield forecasts, especially with regard to independent rigorous model validations, improved consideration of weather extremes, and the transferability of the models to other regions.