Geraldo Gonçalves dos Reis

Effect of spacing on growth and biomass distribution in Eucalyptus camaldulensis, E. pellita and E. urophylla plantations in southeastern Brazil

Abstract The growth and biomass accumulation in different plant parts (including root systems) of Eucalyptus camaldulensis, E. urophylla and E. pellita planted at three spacings (3×1.5 m, 3×3 m and 4×3 m) and three ages (15, 31 and 41 months) were evaluated in the savannah region of central Minas Gerais state in southeastern Brazil. A series of equations were produced to estimate per-tree biomass from age, spacing, diameter and height, and per-hectare biomass using age, spacing and a tally of tree diameters and heights. Average total productivity at age 41 months was of the order E. urophylla>E. pellita≥E. camaldulensis. As spacing increased, individual stems increased in diameter and total biomass; however, total biomass production per hectare decreased. Eucalyptus urophylla had 64.8 vs. 42.8, E. pellita 41.3 vs. 28.9 and E. camaldulensis 35.1 vs. 26.9 Mg ha−1 at 3×1.5 vs. 4×3 m spacings, respectively. Increased spacing levels also decreased the relative amount of growth allocated to the bole of the tree for E. urophylla and E. camaldulensis during the time period of this study and increased allocation to the root system, while E pellita showed relatively small changes. Allocation to the bolewood in E. urophylla changed from 46 to 36%, in E. camaldulensis from 37 to 32%, and E. pellita from 31–34% at 3×1.5 vs. 4×3 m spacings, respectively. Allocation to the root system in E. urophylla changed from 23–30%, in E. camaldulensis from 34–45%, and E. pellita from 37–33% at 3×1.5 vs. 4×3 m spacings, respectively. Thought these results show that some of the biomass changes from species, age and spacing differences are related to distribution, not total biomass production, there were significant differences in total biomass accumulation also. Since larger root systems may increase future yields from coppice growth, the effect of differences in allocation to the root system on future productivity needs to be evaluated.

Effect of spacing and age on nitrogen and phosphorus distribution in biomass of Eucalyptus camaldulensis, Eucalyptus pellita and Eucalyptus urophylla plantations in southeastern Brazil

The nitrogen and phosphorus accumulation in different tree parts (including root systems) of Eucalyptus camaldulensis Dehnh., Eucalyptus urophylla Blake and Eucalyptus pellita F. Muell. planted at three spacings (3 m 1.5 m, 3 m 3 m and 4m 3 m) and at three ages (15, 31 and 41 months) were evaluated in the savanna region of central Minas Gerais state in southeastern Brazil. A series of equations were produced to estimate per-tree nitrogen and phosphorus from age, spacing, diameter and height, and per-hectare nitrogen and phosphorus using age, spacing and a tally of tree diameters and heights. The highest N and P concentrations were observed in foliage (15‐23 g N kg ˇ1 and 0.8‐1.1 g P kg ˇ1 ) and the lowest N concentration in bolewood (2.4‐4.1 g N kg ˇ1 ), while the lowest P concentration was observed in the taproot (0.16‐0.29 g Pk g ˇ1 ). Total biomass N at age 41 months was greatest in E. urophylla (378‐457 kg N ha ˇ1 ), lower in E. pellita (238‐326 kg Nh a ˇ1 ) and lowest in E. camaldulensis stands (204‐240 kg N ha ˇ1 ), depending on spacing. Total biomass P at age 41 months was also greatest in E. urophylla (16.6‐21.8 kg P ha ˇ1 ), and about equal in E. pellita (10.4‐12.8 P ha ˇ1 ) and E. camaldulensis stands (10.4‐12.2 kg P ha ˇ1 ), depending on spacing. As age and spacing increased, individual stems increased in diameter and total N and P, but the relationship between total N and P pools and age and spacing was more variable. # 2000 Elsevier Science B.V. All rights reserved.

Avaliação temporal da florística arbórea de uma floresta secundária no município de Viçosa, Minas Gerais

RESUMO - Avaliou-se a composicao floristica, por um periodo de nove anos, em um fragmento de Floresta Estacional Semidecidual Secundaria localizada no Municipio de Vicosa, Minas Gerais, com o objetivo de se avaliar a dinâmica da vegetacao arborea. A coleta dos dados dessa vegetacao, com diâmetro a altura do peito (DAP a 1,3 m) igual ou superior a 5 cm, foi realizada em 10 locais, em parcelas permanentes. As especies amostradas foram identificadas, sempre que possivel, em niveis de familia, genero e especie. Em nove anos de estudo foram amostradas 161 especies, 114 generos e 48 familias, sendo as familias Leguminosae, Lauraceae, Euphorbiaceae, Myrtaceae, Flacourtiaceae e Meliaceae, as que tiveram a maior riqueza de especies. O indice de diversidade de Shannon-Weaver variou de 2,26 a 3,65, quando analisado para cada local, e de 4,22 a 4,26 para o fragmento como um todo, ao longo de nove anos. O grupo ecologico que mais se destacou foi o das secundarias iniciais, seguido pelas secundarias tardias ou pelas pioneiras, a depender da abertura do dossel do local estudado, indicando que o fragmento se encontrava em estadio medio de sucessao. A variabilidade na composicao floristica em funcao dos locais estudados e na proporcao de especies em cada grupo ecologico era resultante das variacoes na intensidade da acao antropica, bem como das condicoes fisiograficas, em especial exposicao e declividade do terreno. Planos de manejo para essas florestas devem levar em conta essa variabilidade de condicoes ambientais.

Seleção precoce de clones de eucalipto para ambientes com disponibilidade diferenciada de água no solo: relações hídricas de plantas em tubetes

This study was undertaken to identify physiological characteristics of cuttings from five eucalypt clones, growing in small plastic tubes (60 mL) to subsidize early selection for planting in sites with varying soil water availability. Stomatal conductance, leaf transpiration, leaf water potential and net photosynthesis of plants maintained fully irrigated and under water deficit were studied. The clones 1250 and 1260 presented reduction in stomatal conductance and leaf transpiration in water stressed plants, which maintained high leaf water potential. On the other hand, the clones 0321 and 1277 kept exhibiting high leaf stomatal conductance and transpiration and presented sharp decrease in leaf water potential under water stress condition. These two clones presented the highest net photosynthesis after several drying cycles. The clones 1277 presented a significant leaf abscission after the first drying cycle and a prompt recover after being re-watered, which indicates that this clone may tolerate dryer environments.

COMPOSIÇÃO FLORÍSTICA DA REGENERAÇÃO NATURAL DE ESPÉCIES ARBÓREAS AO LONGO DE OITO ANOS EM UM FRAGMENTO DE FLORESTA ESTACIONAL SEMIDECIDUAL, EM VIÇOSA, MG 1

The floristic composition of the natural regeneration in a secondary Seasonal Semideciduous Forest fragment in the Atlantic Forest domain, Southeastern Brazil, was studied in the years 1992, 1995 and 2000. The sampling unit sizes were 0.5x10m, 0.5x20m and 1x20m, respectively, for plant size class 1 (height up to 1 m), class 2 (height from 1 to 3 m) and class 3 (height > 3m and DBH < 5cm). A total of 4,149 individuals were sampled over the inventory period, comprising 42 families and 160 species, being 11.7 % pioneer, 62.1 % early secondary, and 26.2 % late secondary species. Family number did not change and number of species increased with time. Fabaceae, Myrtaceae, Rubiaceae and Lauraceae were the predominant families. Species ingrowth was higher than mortality. Shannon-Weaver diversity index was significantly lower

QUALIDADE DA MADEIRA EM CLONE DE Eucalyptus grandis W. Hill ex Maiden SUBMETIDO A DESRAMA ARTIFICIAL

n The present study aimed at the evaluation of the influence of artificial pruning of Eucalyptus grandis Hill ex Maiden clones on wood quality for sawnboard production, in Southeastern Brazil. Branches were removed to different heights from the ground and number of interventions to reach a 6†m branch-free trunk, with the first pruning intervention starting at the age of 16 months. By the age of 55 months, no significant differences (p>.05) were found for taper, flatness and bow of the first 3†m log as a result of pruning. The clear wood production of the pruning treatments was, on average, 94†% greater than the control. Clear wood production increased with the reduction in the diameter over occlusion (wood knotty core). The pruning wounds smaller than 1.5†cm in diameter showed 0.48 cm stub occlusion extension and the wounds larger than 1.5†cm showed 0.74 cm stub occlusion extension. The branch angle was larger for the thinner branches and had no correlation with pruning. Wood density along the trunk was not affected by artificial pruning, however, it decreased from the top to the base of the first log and increased from pith to bark. The overall results indicate mainly that the genetic material for sawnboard production must present smal diameter branches and pruning must be carried out as early as possible to attain larger clear wood extension.

INFLUENCE OF INITIAL SPACING ON THE STEM SHAPE OF Pinus Taeda L.TREES

The objective of this study was to analyze the effect of spacing on the stem shape of Pinus taeda L. trees. Data from a spacing experiment carried out at the company IGARAS, in Santa Catarina, Brazil, were used for this purpose. The analyzed spacings were: 1.5 x 1.0 m; 2.0 x 1.0 m; 2.5 x 1.0 m; 1.5 x 2.0 m; 2.0 x 2.0 m; 1.5 x 3.0 m; 2.5 x 2.0 m; 2.0 x 3.0 m; and 2.5 x 3.0 m. The taper models tested were those proposed by Demaerschalk, Garay and Biging, with the model of Garay being selected. Through model identity tests, it was verified that the smallest spacings resulted in less conical shape than the largest ones.

Crescimento de plantas de clones de Eucalyptus grandis [Hill ex Maiden] submetidas a diferentes tratamentos de desrama artificial, na região do cerrado

RESUMO – O crescimento em diâmetro a altura do peito (DAP), altura e volume foi avaliado em plantas de clone de Eucalyptus grandis, submetidas a diferentes intensidades de desrama artificial (altura de 1,0; 1,5; e 2,0 m a partir do solo) e idades de aplicacao da primeira intervencao de desrama (20 e 28 meses de idade), em Abaete, MG. A segunda intervencao de desrama em todos os tratamentos foi realizada aos 33 meses de idade, ate atingir 3 m de altura do fuste da planta. Aos 40 meses de idade, observou-se que a desrama artificial nao afetou, significativamente (p>0,05), o crescimento em DAP, altura e volume das plantas submetidas a primeira intervencao de desrama aos 20 meses, porem afetou o DAP e o volume quando a primeira intervencao foi realizada aos 28 meses de idade. Observou-se rapida recuperacao da copa das plantas desse clone, independentemente do tratamento de desrama. Considerando nao ter havido diferenca entre tratamentos para o crescimento das plantas que tiveram a primeira intervencao aos 20 meses de idade e que os galhos vivos ainda apresentavam diâmetro reduzido e praticamente nao existiam galhos mortos por ocasiao da primeira intervencao nessa idade, recomenda-se a aplicacao da desrama nesse clone, na regiao de cerrado, aproximadamente, aos 20 meses de idade, visando obter madeira de melhor qualidade para serraria.

GROWTH OF EUCALYPT CLONE SUBMITTED TO PRUNING AND THINNING

Plants of Eucalyptus grandis clone, established in a 3 x 3 m spacing, were submitted to pruning and thinning. Pruning treatments started at three ages: 16, 20 or 28 months. Three or four pruning interventions were applied at different tree heights to attain a 6 m log free of branches, when pruning started at the age of 16 or 20 months, and two or three pruning were applied for the treatments starting at the age of 28 months. At the age of 55 months, two thinning treatments were applied (control and removal of 35 % of the total planted seedlings). The plant growth after thinning was evaluated for the period between 55 to 93 months by analyzing diameter (DBH), total height (Ht), volume outside bark (V), periodic annual increment after thinning (PAI) and mean annual increment (MAI). At the age of 93 months, there were no significant differences (p>0.05) for the diameter at 1.3 m height (DBH), total height (Ht), volume outside bark (V), periodic annual increment after thinning (PAI) and mean annual increment (MAI) between artificial pruning treatments and for the pruning-thinning interaction. By pruning up to the height of 1.5 m in the first intervention, at the age of 16 months, there was a removal of 80 % of total leaves and branches. In this treatment, 65 % of the individuals presented diameter smaller than 15 cm in comparison to 35 % for the remaining treatments.

THINNING EFFECT ON PLANT GROWTH OF PRUNED EUCALYPT CLONE

A pruned stand of eucalypt clone underwent five thinning treatments with the removal of different proportion of the planted trees, at different ages: a) 0% - unthinned, b) 35% at 55 months, c) 35% at 81 months, d) 70% at 81 months, removing sprouts in the thinned plant stumps and, e) 70% at 81 months, without coppice sprouts removal. By the age of 141 months, the Weibull distribution showed higher number of trees in the smallest diameter classes for the unthinned treatment. The 70% thinning, with thinned coppice sprouts removal, presented higher number of individuals in the largest diameter classes. Height and yield were the smallest with the removal of 70% of the trees at 81 months, maintaining coppice sprouts. The afterthinning periodic annual increment was greater by thinning 35% of the trees at 55 months resulting in greater number of trees in the largest diameter classes as compared to the other treatments. Yield was higher for the unthinned treatment. The results of this study indicated that thinning 70% of the trees at the age of 81 months, with coppice sprout removal, could be recommended to obtain trees of larger diameter for multiproduct.