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The use of height-diameter models have important applications in the management of eucalyptus plantations. The aim of this paper is to provide adequate height models based on the diameter and stand variables that could be easily used and applied to plantation’s management. The data was based on tests located in Espírito Santo and Bahia. A total of 312 plots, including 35 different treatments (different initial planting densities, number and severity of thinning operations, fertilization regimes, among others), and four different clones. This resulted in 2,407 conditions for 85,608 tree measurements. The constructed equations were based on mixed-effect models, in order to accommodate possible autocorrelations, to address variations between sites and to obtain locally calibrated estimates. Among the different model structures and combination of variables tested and presented, the best model showed a coefficient of determination of 0.953 and 0.988, for the fixed and fixed+random parts, respectively. The model included a random factor for measurements-within-tree and tree-within-plot. The bias of the fixed part was 0.208 cm (0.0659%). We believe the models in this study can have broad applications in management and inventory methods applied to plantations.

This study aimed to clarify the environmental factors limiting the height of aged Cryptomeria japonica trees. The study was conducted on C. japonica plantations of about 100 years old at the Boso Peninsula, Japan, where the climatic conditions are almost uniform. Twenty-eight plots measuring 10 &times, 10 m were established on ridges, and 40 plots were established on the middle or lower sections of slopes. The stand ages ranged from 93 to 115 years old. The height of the tallest tree and soil depth (SD) were measured in each plot, and the wetness index (WI) and openness (OP) of each plot were calculated using a digital elevation model. The tree height at the 100-year age (H100) was estimated. The H100 ranged from 16.2 to 44.9 m and was significantly correlated with the logWI (r = 0.78) and OP (r = &minus, 0.70). SD and H100 were significantly correlated in the plots on the ridges but not in the plots on the middle or lower sections of slopes. It indicated that soil water retention capacity might limit tree height in the relatively dry soil conditions. The coefficient of determination adjusted by the number of parameters for H100 predicted using multiple regression analysis with environmental factors of logWI, logWI and OP, or logWI, OP and SD were 0.60, 0.69, and 0.73, respectively. The inclusion of OP and SD in the model improved the prediction of H100, suggesting that the wind and rooting depth could be the influencing factors in determining the height of aged trees. The findings of this study could be used in the planning and management of forestry plantations of long rotation system.

Total tree height (h) is often difficult to measure in natural forests. Regression models based on easily accessed variables like DBH (d) can be an alternative, since their assumptions are validated. The aims of this study are to: (i) calibrate specific and generic h-d models for three forest types (Seasonal Deciduous Forest, DEC; Mixed Ombrophilous Forest, MIX; and Dense Rainforest, DEN) in Santa Catarina state testing the regression assumptions and evaluating model quality; (ii) verify different h-d relationship between forest types. The dataset (1,766 measured tree h and 3,150 estimated h) was collected by Santa Catarina Forest and Floristic Inventory (IFFSC) in 418 systematically located sample plots. Models were calibrated for two datasets, one containing hypsometer measurements, the other h estimations made by field crews. Specific models were calibrated for species with at least 30 sampled trees. Residual normality, randomness and heteroskedasticity were evaluated by analytical methods. Confidence bands were generated by the Working-Hotelling method; z test for means was applied to compare models based on the two databases. The statistical parameters such as corrected Akaike Information Criterion provided evidences that logarithmic models were better adjusted to the data. Both datasets were statistically different for DEN and MIX. Differences in h-d relationships were found between forest types. The use of calibrated h-d models is an alternative for studying the relationships between these variables and to assess vertical structure patterns of forest communities, when h measurements are not feasible, although, for situations that more accurate h values are needed, they will not always provide reliable predictions. Em florestas naturais, a altura total das árvores (h) é, muitas vezes, difícil de medir. Nesses casos, modelos de regressão baseados em variáveis de fácil medição, como o DAP (d), são uma alternativa, desde que seus pressupostos sejam atendidos. Neste estudo, objetivou-se i) o ajuste de modelos hipsométricos para três tipologias florestais de Santa Catarina (Floresta Estacional Decidual, Floresta Ombrófila Mista, Floresta Ombrófila Densa), testando os pressupostos e avaliando a qualidade dos ajustes; ii) verificação de diferenças das relações hipsométricas entre as tipologias florestais e entre os modelos ajustados baseados em alturas medidas e estimadas. Os dados de 1.766 alturas medidas e 3.150 alturas estimadas em campo foram coletados pelo Inventário Florístico Florestal de Santa Catarina (IFFSC), em 418 unidades amostrais. Os modelos foram ajustados para ambos os conjuntos de dados. Modelos específicos foram ajustados para espécies com ≥ 30 árvores medidas; normalidade, aleatoriedade e homoscedasticidade dos resíduos foram avaliadas analiticamente. Bandas com intervalos de confiança foram construídas pelo método Working-Hotelling; teste z para médias foi aplicado para comparar os modelos baseados nos dois conjuntos de dados. Parâmetros estatísticos como o AIC evidenciaram melhor ajuste dos modelos logarítmicos. Foram encontradas diferenças nas relações h/d entre as tipologias florestais (DEN e MIX) e entre os conjuntos de dados. O uso de modelos hipsométricos é uma alternativa para estudar a relação h/d e para determinar padrões da estrutura vertical em comunidades florestais, quando a medição de h não é viável, embora em casos da necessidade de maior acurácia das alturas estimadas, os modelos nem sempre possam fornecê-las.

The use of height-diameter models have important applications in the management of eucalyptus plantations. The aim of this paper is to provide adequate height models based on the diameter and stand variables that could be easily used and applied to plantation’s management. The data was based on tests located in Espírito Santo and Bahia. A total of 312 plots, including 35 different treatments (different initial planting densities, number and severity of thinning operations, fertilization regimes, among others), and four different clones. This resulted in 2,407 conditions for 85,608 tree measurements. The constructed equations were based on mixed-effect models, in order to accommodate possible autocorrelations, to address variations between sites and to obtain locally calibrated estimates. Among the different model structures and combination of variables tested and presented, the best model showed a coefficient of determination of 0.953 and 0.988, for the fixed and fixed+random parts, respectively. The model included a random factor for measurements-within-tree and tree-within-plot. The bias of the fixed part was 0.208 cm (0.0659%). We believe the models in this study can have broad applications in management and inventory methods applied to plantations.