Na região de Piracicaba, grande parte dos pequenos produtores cultivam cana-de-açúcar em áreas de alta declividade, mas a mecanização da colheita tem inviabilizado seu cultivo nesta condição. Sistemas agroflorestais (SAFs) podem ompatibilizar a produção da cultura neste cenário, com a conservação de recursos naturais, porém, há falta de pesquisa sobre seu cultivo nestes sistemas. Portanto, o uso de modelos de simulação e avaliações de campo da interface árvore-cultura podem desempenhar importante papel para investigar seus potenciais e restrições. Assim, identificamos e selecionamos terras e árvores para cultivo dos SAFs e avaliamos o crescimento e produção de plantas dos SAFs cana-de-açúcar x seringueira e cana-de-açúcar x eucalipto. Realizamos dois experimentos de campo e utilizamos o modelo WaNuLCAS e um modelo que simula a disponibilidade de radiação para culturas intercalares, acionando-o com a produção de matéria seca da cultura. SAFs em aléias em contorno são alternativa viável para cultivo de cana-de-açúcar no município de Piracicaba, havendo diversas espécies arbóreas exóticas e nativas que podem compor estes SAFs, destacando-se seringueira e eucalipto. Luz e água são limitantes ao crescimento da cultura e há aumento da competição de acordo com o crescimento das árvores. A importância relativa entre competição abaixo e acima do solo depende da distância das árvores. Contudo, o SAF cana-de-açúcar x eucalipto tem produção semelhante ao monocultivo de cada espécie. Os modelos permitiram avaliar os SAFs e orientar experimentos, mas suas indicações devem ser verificadas em experimentos de campo. A recomendação dos SAFs deve ser feita após análise econômica dos mesmos. / In Piracicaba, many smallholders grow sugarcane in areas of high solpe, but the mechanization of the harvest process has made inviable its cultivation under this situation. Agroforestry systems (AFs) are an alternative that may join the cultivation of the crop under this scenario with conservation of natural resources. However, there is lack of research of its cultivation in AFs. Therefore, the use of simulation models and evaluation of on-farm tree-crop interfaces may play an important role to investigate its potentials and restrictions. Thus, we identified and selected lands and trees to the cultivation of the AFs and assessed plant growth and yield of sugarcane x rubber and sugarcane x eucalyptus AFs. We did two field experiments and used the WaNuLCAS model and another one that simulates the available irradiance for intercrops, related with their dry matter production. Contourhedgerows are a feasible alternative for sugarcane cultivation in Piracicaba, where many tree species may be part of it, especially rubber and eucalypts. Light and water are limiting factors for crop growth and competition increases with tree growth. The relative importance of each variable depends on the distance from the trees. However, the sugarcane x eucalyptus AF has similar production of the monocropping of each specie. The models allowed to assess the AFs and to drive field trials, but their results should be verified in experiments. The recomendation of the AFs should be done after their economic analysis.

Thesis (Ph. D.)--Ohio State University, 2006. / Title from first page of PDF file. Includes bibliographical references (p. 102-110).

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Smallholder tree planting is a pathway recognized within Forest Transition Theory (FTT), but its contributing factors are not fully explored at the household level. This study examines the effect of socio-economic and biophysical characteristics, access to extension services, land tenure, labour availability, and attitudes toward tree cover on smallholder planting and willingness to plant for environmental and economic purposes at the household level. Data was collected from 146 households in Mocoties, Merida, Venezuela. Logistic models revealed that area of property, area of productive land, presence of natural sources of water, gender of respondent, number of generations that have farmed the property, income, percent income from farming activities, land title, harvest rights, labour availability and attitudes toward tree cover have significant influence on smallholder’s tree planting and willingness to plant. Future research needs to focus on factors that affect environmentally motivated smallholder tree planting where fewer significant variables were found.

Smallholder tree planting is a pathway recognized within Forest Transition Theory (FTT), but its contributing factors are not fully explored at the household level. This study examines the effect of socio-economic and biophysical characteristics, access to extension services, land tenure, labour availability, and attitudes toward tree cover on smallholder planting and willingness to plant for environmental and economic purposes at the household level. Data was collected from 146 households in Mocoties, Merida, Venezuela. Logistic models revealed that area of property, area of productive land, presence of natural sources of water, gender of respondent, number of generations that have farmed the property, income, percent income from farming activities, land title, harvest rights, labour availability and attitudes toward tree cover have significant influence on smallholder’s tree planting and willingness to plant. Future research needs to focus on factors that affect environmentally motivated smallholder tree planting where fewer significant variables were found.

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Ground based forest inventory surveys can provide highly accurate measurements of tree and stand characteristics, but are time-consuming and costly, and therefore typically limited to number of sample plots.  Estimating tree and stand characteristics from digitised aerial photographs can provide measurements from the whole stand, but is less accurate.  The goal of this study was to evaluate the application of scanned, stereo aerial photography and digital photogrammetry in combination with tree crown delineation techniques to measure tree and stand characteristics in two sites in Scotland, Rosarie and Leanachan forests.  Existing medium-resolution scanned images of true colour aerial photographs (1:10,000) were used to derive Digital Elevation Models (DEMs) of the forest canopy and digital orthophotographs.  Tree crown delineation techniques were used on the derived digital orthophotographs and tree crown measurements including crown area and coordinates of each crown were derived.  The DEMs in combination with Digital Terrain Models (DTMs) derived from digital contour maps, were used for the estimation of tree and stand heights.  Equations derived from regression analysis of individual tree measurements on the ground, and the orthophotographs from Rosarie forest, were used for the estimation of tree and stand characteristics of both sites. For Rosarie forest the estimations of stand top height, basal area, stand volume stand biomass and stand density (~23.7%) were similar with the ground measured stand characteristics (<span lang=EN-GB style='font-family:Symbol'>±10%), where as for Leanachan forest the estimations were less accurate due to the non-optimum illumination conditions during the acquisition of the aerial photographs. The level of accuracy achieved in this study is adequate for measuring tree and stand characteristics, if the acquisition conditions of aerial photographs are optimal.  Higher level of accuracy may be possible, but requires more accurate DTMs, possibly derived using active airborne remote sensing sensors.

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