RESUMENEn este trabajo se presentan los resultados alcanzados en la determinación del contenido de lignina así como de su calidad (relación H/G) en muestras de madera de Pinus caribaea var caribaea de tres localidades en la provincia de Pinar del Río, Cuba. El estudio se realizó en el Instituto de Investigación Científica Tropical de Lisboa, Portugal, en el marco del Proyecto GEMA. La técnica utilizada fue la Pirólisis analítica. Los resultados que se muestran representan el promedio de tres corridas experimentales y se obtuvieron valores cercanos al método Klason utilizado como referencia. Se encontró una correlación aceptable entre los contenidos del lignina-pirólisis y lignina Klason para esta especie, lo cual permite calcular el contenido de lignina Klason a través del contenido de ligninapirólisis. La pirólisis analítica es de gran utilidad en los programas de mejoramiento genético, en que es necesario el análisis de muchas muestras, ya que la introducción de parámetros como la composición química de la madera, induce al desarrollo de métodos expeditos de caracterización, reproducibles y de bajo costo, una vez que los métodos tradicionales son lentos, requieren mucha mano de obra y son de elevado costo.
El trabajo tuvo como fin determinar un turno de corta para Pinus caribaea Morelet var. caribaea
The present study was carried out to compare the performances of regression models and Artificial Neural Networks (ANNs) in hypsometric relationships modeling and to analyze the influence of ANN type and sample size on ANN performance. The database was consisted by 65 circular plots of 500 m² in which Diameter at Breast Height - DBH (cm) and Total Height - Ht (m) of 2538 trees were measured in plantations of Pinus caribaea var. caribaea in Macurije forest company, Cuba. The study was carried out in three stages: i) Fit of traditional hypsometric models and sigmoidal growth models; ii) ANNs training and comparison of the selected ANN with the regression model selected; iii) Analysis of sample size and ANN type influences on the estimates precision by means of a completely random experimental design with 5x2 factorial arrangement, with the factors sample size (N) and ANN type (R). The results indicated that the best equation to estimate trees heights was that of Gompertz. The ANNs MLP 1-4-1 and MLP 8-4-1 were superior to the selected equation (Gompertz). Multi-Layer Perceptron ANNs generated more accurate estimates and their performances were less influenced by the sample size.
RESUMOEmbora os desbastes, principalmente os seletivos, sejam partes das atividades silviculturais planejadas, os mesmos não são realizados sistematicamente na maioria das empresas florestais. Na maioria das áreas dessas empresas destinadas a produzir principalmente madeira serrada, são apenas definidos grandes espaçamentos iniciais prevendo a não realização de desbaste. Essa prática não favorece a obtenção de árvores de maiores dimensões com as características dentrométricas exigidas pelas serrarias. Por isso, a presente pesquisa teve como objetivo, simular desbastes para diferentes classes de sítio em plantios de Pinus caribaea Morelet var. caribaea Barr. & Golf. estabelecidos para a produção de madeira para serraria na Empresa Florestal Integral (EFI) Macurije, Pinar del Río, Cuba. Com dados de parcelas permanentes, nas quais foram medidas as variáveis dendrométricas Diâmetro à altura do peito (DAP) e Altura total (Ht), foi ajustado o sistema de prognose de produção de Buckman. Utilizando a equação de prognose de área basal, foram realizadas simulações mediante a aplicacão de diferentes intensidades de desbaste nas cinco classes de sitio predeterminadas na empresa. As vistas aéreas e em perspectivas das estruturas dos povoamentos remanescentes foram realizadas com o software SVS (Stand Visualization System). A alternativa ou intensidade de desbaste mais adequada sendo aquela que não é considerada severa, apresentando uma área basal remanescente superior a 19 m2.ha-1 (G > 19 m2.ha-1), os resultados das simulações indicaram que a intensidade de 20% foi a mais adequada para o sítio I, 15% para o sítio II e 10% para os sítios III, IV e V. PALAVRAS-CHAVE: Desbaste seletivo, Índice de sítio, Madeira para serraria, Prognose de área basal. ABSTRACTAlthough thinnings, especially selective thinnings, are part of planned silvicultural activities, they are not systematically performed in most forest companies. In most areas of these companies destined to produce mainly sawn wood, only large initial spacings are defined, foreseeing the non-thinning. This practice does not favor the obtaining of larger trees with the dendrometric characteristics demanded by sawmills. Therefore, the present research had as objective, to determine the adequate thinning intensities for different classes of site in plantations of Pinus caribaea Morelet var. caribaea Barr. & Golf. established for lumber production for the Integrated Forest Company (IFC) Macurije, Pinar del Río, Cuba. With data from permanent plots, in which the dendrometric variables Diameter at Breast Height (Dbh) and Total Height (Ht), the Buckman production prognosis system was fitted. Using the basal area prognosis equation, simulations were performed by applying different thinning intensities to the five predetermined site classes in the company. The aerial and perspective views of the structures of the remaining stands were carried out with the SVS (Stand Visualization System) software. The most suitable alternative or intensity of thinning is one that is not considered se...
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