A consideração de condicionantes espaciais em modelos de otimização matemática para lidar com o manejo de florestas públicas e privadas é cada vez mais comum. Um desses condicionantes é a imposição de corredores de conectividade para o abrigo e movimentação da fauna e flora, principalmente devido ao elevado grau de fragmentação das áreas de vegetação nativa, o qual exerce um forte impacto na probabilidade de sobrevivência de várias espécies no longo prazo. O objetivo deste trabalho é o desenvolvimento de metodologias auxiliares que permitam ao gestor florestal garantir uma conectividade mínima entre fragmentos de vegetação nativa utilizando unidades de manejo da floresta de produção com determinadas características, interligando fragmentos adjacentes a floresta de produção concomitantemente com a produção de bens e serviços florestais. Duas técnicas foram consideradas; um modelo matemático de programação linear inteira mista e uma heurística denominada heurística da RazãoR. Os dois métodos consideraram o estabelecimento de corredores de conectividade em todos os períodos do horizonte de planejamento simultaneamente, e as equações inseridas permitem ao gestor controlar a qualidade das unidades de manejo aptas a formar o corredor. O modelo de programação linear inteira mista proposto para resolução desse problema faz uso de uma importante propriedade da programação em redes, permitindo a inserção das restrições de conectividade sem adicionar variáveis binárias além daquelas necessárias ao modelo sem conectividade. A solução ótima foi obtida tanto o problema com incorporação de conectividade como para o problema sem conectividade, sendo a diferença entre valores das respectivas funções objetivo o custo de oportunidade do estabelecimento dos corredores. Na heurística da RazãoR, utilizou-se um algoritmo recursivo baseado na Teoria de Grafos e na programação dinâmica para se avaliar o déficit de conectividade das soluções. Dois estudos de caso foram utilizados para a aplicação das técnicas propostas, uma fazenda de uma empresa de celulose do estado de São Paulo, denominada Fazenda Empresarial, e o Parque Estadual Anhanguera. Os dois métodos alcançaram o objetivo de elaborar planos otimizados de manejo florestal estabelecendo uma conectividade mínima entre os fragmentos de vegetação nativa. O custo avaliado para o estabelecimento da conectividade da Fazenda Empresarial foi de 0,051% do valor da função objetivo do problema sem conectividade. A heurística mostrou-se eficaz em encontrar ótimas soluções viáveis, com valores da função objetivo variando de 99,71% a 99,83% do valor encontrado pelo modelo de programação linear inteira mista, após um número médio de 48 iterações. Entretanto, o tempo médio para a heurística encontrar uma solução para o problema foi de dez minutos e vinte e cinco segundos, sendo cinco vezes superior ao tempo necessário para o modelo matemático retornar a solução ótima (um minuto e cinqüenta e quatro segundos). A provável causa do baixo desempenho da heurística em termos de tempo para encontrar uma solução se encontra no método de programação que não buscou gerar um código rápido, deixando espaço no futuro para melhorias quando problemas de maior escala precisem ser resolvidos e a solução de grandes problemas de programação linear inteira mista não possa ser encontrada pelos softwares convencionais. / The consideration of spatial constraints into mathematical optimization models to deal with the management of public and private forests is increasingly common. Due to the increasing fragmentation of natural forests and decreasing species survival\'s probability, an important constraint considers the existence of corridors that work as shelters to allow for the movement and exchange of fauna and flora species. The aim of this paper is the development of auxiliary methodologies to support forest manager in creating a minimal net of corridors formed by industrial forest stands with certain characteristics that connect industrial stands and still conciliate production and environmental concerns. Two techniques were considered; a mixed integer linear programming model and a heuristic procedure called the R-ratio method. Both techniques dealt with the simultaneous incorporation of connectivity corridors over all planning periods in the planning horizon, and allowed the manager to control the quality of the forest stands that can take part of the corridors. The mixed integer linear programming model created to solve this problem relies on an important property of network optimization models, allowing the insertion of the connectivity restrictions without increasing the number of binary variables already present in the model with no connectivity constraints. The optimal solution was achieved in both models, and the difference between the two objective functions revealed the opportunity cost of establishing the corridors. In the R-ratio heuristic, a recursive algorithm based on Graph Theory and on dynamic programming was used. The technique was applied in two cases, a farm of a owned by a pulpwood company in the State of São Paulo, referred to as the Company Farm, and the Anhanguera Forest State Park. Both methods optimized the objective and produced forest management plans that resulted in minimal connectivity among all fragments of native forests. The cost of creating corridor on the Company Farm represents 0,051% of the total objective function value for the no connectivity formulation. The R-ratio heuristic was effective in finding good viable solutions to the problem, with values to the objective function varying from 99,71% to 99,83% of the value found to the optimal solution of a mixed integer linear programming, after an average of 48 iterations. Meanwhile, the heuristic took an average time of ten minutes and twenty five seconds to find a viable good viable solution, representing five times the time required by the mixed integer formulation to find an optimal solution. The probable cause of this low performance in terms of time to find a solution is that the heuristic was not programmed to efficiently generate fast executable codes, leaving space for future improvements if necessary when dealing with large scale problems and in the absence of conventional software capable of dealing with large scale mixed integer linear programming problems.

<p>In the Central Hardwood Region, the quantity and quality of hardwood timber critically depend on forest management decisions made by private landowners, since they hold the largest share of woodlands, some of which are plantations. These plantations are in a unique and critical position to provide much-needed hardwood resources. However, there is a lack of research and tools enabling rigorous assessments of profitability of long-term investments in hardwood plantations. Partially due to this, the majority of these privately held plantations remain unmanaged.</p> <p>This study aims at providing scientific evidence and tools to help promote forest management on hardwood plantations held by private landowners. To this end, I demonstrate in Chapter 1 an economic-modeling approach that minimizes establishment costs while ensuring free-to-grow status by year 5, and crown closure by year 10. Using temperate hardwoods such as black walnut and red oak as focal species, I find a black walnut plantation can attain crown closure in year six at the lowest cost ($4,540/ha) with 6 feet x 7 feet spacing, herbicide application for the first year, and fencing. For red oak, the minimum-cost option ($5,371/ ha) which achieves crown closure in year 10 requires a planting density of 6 feet x 7 feet, herbicide application for the first three years, and fencing. Modelling uncertainty in growth and mortality in a stochastic counterpart shifts optimal solutions to denser plantings for black walnut; planting more trees is, thus, risk mitigative. Based upon these research outcomes, I identify the tradeoffs between efficacy of treatments towards establishment success viz a viz their relative costs which serve as a solid foundation for the assessment of subsequent management strategies.</p> <p>Next, in chapter 2, I first calibrate growth, yield, and crown-width models for black walnut trees with existing and new tree measurements on selected Hardwood Tree Improvement and Regeneration Center (HTIRC) plots. Using spatial information on trees, I develop an individual tree level thinning model and simulate their post-thinning growth and yield. Significant predictors of annual diameter growth between years 10 to 18 include the initial tree DBH, forest edge effects, distance-dependent neighborhood competition, and tree age. Significant edge effects exist up to 3 rows and 3 trees from the non-forested edge. A tree on the perimeter rows grows 0.30 cm (0.12in.) in DBH more per year than the interior trees, between years 10 to 18. Next, I dovetail my results from the spatially explicit thinning model with the USFS Forest Vegetation Simulator (FVS) to understand the impacts of different scenarios of planting densities, site productivities, thinning treatments, and expected yields (as percentage of the total volume) of veneer sawlogs to quantify the growth and profitability from the mid-rotation until the final harvest. To support the attendant financial analyses, I incorporate risk into these projections by simulating stochastic windthrows based on certain assumptions. My projections suggest that, without the threat of windthrow damage, the net present day value (NPV) could exceed $4,900 per acre on the highest quality sites (SI =100) and high densities at planting (6 feet x 6 feet), assuming 10% or more of final volume was veneer and using a 3% discount rate. In contrast, under simulations of probable windthrow disturbances from mid-rotation to final harvest, the chances that standing timber value at harvest exceeds $5,000 per acre are 43.13% for a 96- and 90-year rotation and increase to 45.48% for 75 and further to 56.04% for 60.</p>