Eucalyptus Grandis Hill Research Articles

Litterfall production modeling based on climatic variables and nutrient return from stands of Eucalyptus grandis Hill ex Maiden and Pinus taeda L.

Litterfall production modeling based on climatic variables and nutrient return from stands of Eucalyptus grandis Hill ex Maiden and Pinus taeda L.

Differential effects on soil water repellency of Eucalyptus and Pinus plantations replacing natural pastures

ABSTRACT Land-use changes from native pastures to forest plantations in humid temperate areas have raised concerns about their potential impact on the environment. This study aimed to assess the effects of such changes on soil water properties, focusing on the impact of the forest species planted and their relationship with changes in soil C content. Specifically, we aimed to identify the development of surficial soil hydrophobicity and changes in soil water holding capacity. A long-term forest experiment with variable planting densities (816, 1111, and 2066 trees ha -1 ) of Eucalyptus grandis Hill ex Maiden and Pinus taeda L. was established in 2004 on native pasture vegetation. Undisturbed soil samples (0.00-0.03 m soil layer) were extracted from the experiment and surrounding pastures and soil water repellency was determined by the water drop penetration time (WDPT) method at three soil matric potential levels (SMP). Bootstrapping was used to test if the sample size was sufficient to obtain robust results. Replacing native pastures with forest plantations significantly increased surficial soil hydrophobicity, which was more pronounced under Eucalyptus grandis than under Pinus taeda. Soil water repellency increased with decreasing SMP, particularly in land-uses that generated higher initial hydrophobicity. Additionally, the soils under forest cover had less water retention capacity than those under pastures at each SMP, with larger differences when the soil was dried to more negative SMP. More research is necessary to determine if soil alterations from converting native pastures to forest plantations in temperate climates will lead to a significant decrease in soil water holding capacity and an increase in hydrophobicity at deeper depths.

Can diameter and log end splittings be a good indicator of board end splitting in 21-year-old Eucalyptus grandis Hill ex-Maiden?

Eucalyptus spp. are currently cultivated in Brazil. In this article we highlight Eucalyptus grandis with its potential for mechanical processing. After felling trees, the splitting that occurs at the end of logs and boards obtained during mechanical processing represents an indirect measure of the level of growth stress present in the living trees. Even though such splitting can cause significant losses in the use of wood, knowledge of this pattern is still sparse. The most suitable eucalyptus trees for the production of sawn wood can be selected by evaluating the effect of the release of growth stresses in the form of cracks. To address this gap, we herein evaluate the effects of end splitting in logs and boards, resulting from the release of growth stresses during the felling of trees and mechanical processing, as a function of the diameter of 48 Eucalyptus grandis Hill ex-Maiden trees aged 21 years old. Splitting at the ends of boards in the green and dry states have a low relationship with the diameter of the logs, but it is not related to the end splitting of the tree logs. A high positive relationship was found between dry board splitting and green board splitting. Therefore, it is possible to estimate with accuracy the evolution of green board splitting according to the drying of the wood. Boards lose, on average, 44 cm (15%) from cracks, or an average of 32 cm (11%) from growth stresses and 12 cm (4%) from drying stresses. Green and dry board splitting decreased significantly from pith to bark. The splitting of dry and green boards had no significant variation between the analyzed positions of the log along the height of the tree.

Agroclimatic zoning for eucalyptus in the southern mesoregion of Bahia State, Brazil

Forestry promotion is one of the approaches to forestry production with an increasing tendency in Brazil. The objective of this work was to present an agroclimatic zoning (AGZ), based on environmental conditions necessary for the planting of four species of eucalyptus in the southern mesoregion of Bahia State, Brazil, on a surface of 54,642.35 km². AGZ was proposed for Eucalyptus grandis Hill, E. urophylla, E. camaldulensis and Eucalyptus urograndis (E. grandis X E. urophylla), using geographic information systems for crossing spatial variables of temperature, precipitation, water deficit, evapotranspiration, soils, altitude, slope, conservation units and land use. The region showed planting aptitude of 27.93, 11.87, 3.74 and 1.70%, for E. grandis, E. urophylla, E. camaldulensis and Eucalyptus urograndis, respectively. The AGZ is an important alternative to minimize, in the long term, the negative effects of a monoculture with a high rate of transpiration that could compromise environmental sustainability and reduce water availability in a region.

Antifungal activity of poly(ε-caprolactone) nanoparticles incorporated with Eucalyptus essential oils against Hemileia vastatrix.

Coffee (Coffea L.) is one of the main crops produced globally. Its contamination by the fungus Hemileia vastatrix Berkeley and Broome has been economically detrimental for producers. The objective of this work was to extract and characterize the essential oils from Eucalyptus citriodora Hook, Eucalyptus camaldulensis Dehn and Eucalyptus grandis Hill ex Maiden, produce and characterize nanoparticles containing these essential oils and evaluate the invivo and invitro antifungal activity of free and nanoencapsulated essential oils. The principal constituent of the essential oil from E. citriodora was citronellal; that from E. grandis was α-pinene; and that from E. camaldulensis was 1,8-cineol. The invitro antifungal activity against the fungus H. vastatrix was 100% at a concentration of 1000 μl l-1 for all the oils and nanoparticles containing these natural products. The sizes of the nanoparticles produced with the essential oils from E. citriodora, E. camaldulensis and E. grandis were 402·13 nm, 275·33 nm and 328·5 nm, respectively, with surface charges of -11·8 mV, -9·24 mV and - 6·76 mV, respectively. Fourier transform infrared analyses proved that the encapsulation of essential oils occurred in the polymeric matrix of poly(ε-caprolactone). The incorporation of essential oils into biodegradable poly(ε-caprolactone) nanoparticles increased their efficiency as biofungicides in the fight against coffee rust, decreasing the severity of the disease by up to 90·75% after treatment with the nanoparticles containing the essential oil from E. grandis.

Differences in Transpiration Characteristics among Eucalyptus Plantations of Three Species on the Leizhou Peninsula, Southern China

How much transpiration water consumption varies between eucalyptus species is unknown, making the suitability of a particular eucalyptus species for large-scale planting in a given area, or whether interspecific differences need to be taken into account for eucalyptus water consumption estimates, uncertain. Here, Eucalyptus camaldulensis Dehnh. (Ec), Eucalyptus pellita F. v. Muell. (Ep), the most resistant species, and Eucalyptus urophylla S.T. Blake × Eucalyptus grandis Hill ex Maiden (Eug), the most widely planted species, were monitored for sap flow. Their stand transpiration was also estimated and its relationship to various influencing factors analyzed for the same stand age and site, and predictive models for daily transpiration (T) developed. The results showed that the T of all eucalyptus species was jointly influenced by meteorological factors, soil water content (SWC), and leaf area index (LAI), with great variation in the T response to each influencing factor among species. Accordingly, we developed species-specific transpiration prediction models that could adequately explain the changed T of each species (R2-values: 0.863–0.911). There were significant differences in the stand daily mean sap flow density (JC) and transpiration among the three species. Although Ec had a significantly lower JC than Ep, it was significantly higher than Eug on all timescales, where the mean annual JC of Ep (0.11 cm min−1) was 1.4 and 2.6 times that of Ec (0.08 cm min−1) and Eug (0.042 cm min−1), respectively. Transpiration of Eug was significantly less than Ep, but significantly greater than Ec on all timescales, where the annual transpiration of Ep (743.41 mm) was 2.4 and 1.5 times that of Ec (311.52 mm) and Eug (493.58 mm), respectively. These results suggest that interspecific differences cannot be ignored when estimating transpiration rates in Chinese eucalyptus plantations, whose amount of water use should be considered when choosing the most optimal species to plant regionally.

Ecological niche differences regulate the assembly of bacterial community in endophytic and rhizosphere of Eucalyptus

The relationship between microorganisms and plants has been a hot topic of research because of its direct link to plant health and productivity, and these interactions are not limited to the soil. The structural and ecological variation of bacterial communities due to spatial isolation in different parts of plants is still unclear. Whether intensive management of Eucalyptus plantations affects this variation should also be concerned. To investigate the mechanisms underlying bacterial changes in different ecological niches of Eucalyptus and the stability of bacterial communities after continuous high-intensity planting of Eucalyptus, we studied the effects of long-term plantation of Eucalyptus on the structure, assembly patterns, and interactions of the bacterial community. Woodlands that planted with Eucalyptus urophylla S.T. Blake × Eucalyptus grandis Hill ex Maiden (Eucalyptus urograndis, hereafter E. urograndis) in three generations (10 years after planting) were selected for study, and the woodlands were cleared and replanted with E. urograndis. Rhizosphere soil, roots, stems, branches, and leaves of E. urograndis differing in age (2, 4, and 6 years) after planting were sampled, and the rhizosphere soil bacteria and endophytic bacterial communities of different parts were determined using the 16S rRNA technique. We detected structural variation in the soil and endophytic bacterial communities as well as variation in community assembly. Stochastic processes made large contributions to the assembly of highly abundant soil bacterial communities, as well as low-abundant endophytic bacterial communities of the branches and leaves (especially leaves), and this pattern may be strongly related to the ecological niches of the bacteria. The bacterial correlation network demonstrated that the properties of Eucalyptus soil and their endophytic bacterial communities can vary 6 years after successive plantings. Thus, measures should be taken to ecologically restore Eucalyptus woodlands after 15 years of high-intensity planting to ensure the stability of microbial community structure, the maintenance of adequate ecological properties during Eucalyptus planting, and the sustainable production and management of Eucalyptus plantations.

Optimization of genetic gain in different variables for Eucalyptus grandis Hill ex Maiden breeding

Optimization of genetic gain in different variables for Eucalyptus grandis Hill ex Maiden breeding

Expression Patterns and Regulation of Non-Coding RNAs during Synthesis of Cellulose in Eucalyptus grandis Hill

Cellulose, an essential structural component in the plant cell wall and a renewable biomass resource, plays a significant role in nature. Eucalyptus’s excellent timber tree species (including Eucalyptus grandis Hill) provide many raw materials for the paper and wood industries. The synthesis of cellulose is a very complex process involving multiple genes and regulated by various biological networks. However, research on regulating associated genes and non-coding RNAs during cellulose synthesis in E. grandis remains lacking. In this study, the wood anatomical characteristics and chemical indexes of E. grandis were analyzed by taking three different parts (diameter at breast height (DBH), middle and upper part of the trunk) from the main stem of E. grandis as raw materials. The role of non-coding RNAs (Long non-coding RNA, lncRNA; Micro RNA, miRNA; Circle RNA, circRNA) on regulating candidate genes was presented, and the network map of ceRNA (Competing endogenous RNA) regulation during wood cellulose biosynthesis of E. grandis was constructed. The transcriptome sequencing of nine samples obtained from the trunk of the immature xylem in E. grandis at DBH, middle and upper parts had a 95.81 G clean reading, 57,480 transcripts, 7365 lncRNAs, and 5180 circRNAs. Each sample had 172–306 known miRNAs and 1644–3508 new miRNAs. A total of 190 DE-lncRNAs (Differentially expressed long non-coding RNAs), 174 DE-miRNAs (Differentially expressed micro RNAs), and 270 DE-circRNAs (Differentially expressed circle RNAs) were obtained by comparing transcript expression levels. Four lncRNAs and nine miRNAs were screened out, and the ceRNA regulatory network was constructed. LncRNA1 and lncRNA4 regulated the genes responsible for cellulose synthesis in E. grandis, which were overexpressed in 84K (Populus Alba × Populus glandulosa) poplar. The cellulose and lignin content in lncRNA4-oe were significantly higher than wild type 84K poplar and lncRNA1-oe. The average plant height, middle and basal part of the stem diameter in lncRNA4-oe were significantly higher than the wild type. However, there was no significant difference between the growth of lncRNA1-oe and the wild type. Further studies are warranted to explore the molecular regulatory mechanism of cellulose biosynthesis in Eucalyptus species.

Comparative Dynamics of Nutrient Release through Litter Decomposition in Eucalyptus grandis Hill ex Maiden and Pinus taeda L. Stands

The installation of commercial stands with exotic forest species on low fertility soils originally covered by native pastures is an unusual situation worldwide. In recent years, the area occupied by forest systems designed for pulp or wood production with immediate replanting has increased strongly in the Pampean region of South America. In this context, the study of nutrient recycling from forest litter decomposition acquires particular relevance. This work seeks to evaluate and compare the nutrient release from the decomposition of forest litter produced by 14-year-old Eucalyptus grandis Hill ex Maiden and Pinus taeda L. stands and test the applicability of a new sampling methodology in the nutrient recycling assessment. For two years, the evaluation of N, P, K, Ca, Mg, Fe, Mn, Cu and Zn dynamics during litter decomposition was carried out. In general, K concentration decreased through decomposition, meanwhile, all other nutrients showed some degree of immobilization, but this was counteracted by biomass loss for most of them. This mainly resulted in net nutrient release from litter. A higher release rate of all nutrients from P. taeda forest litter compared to E. grandis, with the exception of Mn, was verified. Fe immobilization was observed in both species showing a higher immobilization rate in E. grandis compared to P. taeda. Finally, Zn exhibited immobilization processes in E. grandis and releases in P. taeda. This might suggest higher temporal and quantitative availability of nutrients in P. taeda, due their faster return to the soil. These findings could be relevant in the development of models for sustainable management, adapting the demand for nutrients to the supply during forest rotations.

Improvement in mechanical, physical and biological properties of eucalyptus and pine woods by raw pine resin in situ polymerization

A raw pine resin, which is a cheap, renewable and easily obtainable forest resource, was used to impregnate two different fast-growing solid woods (Eucalyptus grandis Hill Maiden and Pinus elliottii Engelm) and in situ polymerized to improve their hygroscopic, chemical, morphological, mechanical, and thermogravimetric properties. Biodegradation resistance against subterranean termites and white-rot fungus was also addressed. The treatment yielded changes in colorimetric properties, dimensional stability and surface hydrophobicity. Compared to its respective untreated wood, the treated pine one presented increases within 40–50 % in ASE, whereas the treated eucalyptus wood showed negative values around -15 % in this same comparison. Increases in MOE (70 %) and MOR (50 %) were obtained for the pine wood, whereas the same properties were unaffected for the eucalyptus wood. Thermal and biological properties of both woods were also positively affected. These results were associated with the solidified raw pine resin inside the wood structure, which was confirmed by infrared spectroscopy and SEM images, especially for the pine due to its large and long tracheids, as well as its lignin content and overall composition.

Physiological response to heat stress and ingestive behavior of lactating Jersey cows in silvopasture and conventional pasture grazing systems in a Brazilian subtropical climate zone.

The aim of this study was to evaluate the physiological response to heat stress and ingestive behavior of Jersey cows in silvopasture and conventional pasture grazing systems. The experiment was carried out during the warm season, spanning spring, summer, and fall seasons in the Brazilian subtropical climate zone. Twelve lactating Jersey cows were observed in rotational grazing on Cynodon nlemfuensis Vanderyst and Panicum maximum Jacq. Treatments were composed of different grazing systems (silvopasture and conventional pasture). The silvopasture grazing system had eucalyptus trees (Eucalyptus grandis Hill ex Maiden) with an average height of ≈ 10 m and row spacing of 20 m. In the conventional pasture grazing system, there were no rows of eucalyptus and no other type of tree or structure to provide shade to the animals. During the summer and fall periods of evaluation, the silvopasture animals presented a lower respiratory rate, whereas during the spring and fall evaluation periods, these animals presented a lower rectal temperature. Cattle in the silvopasture showed longer grazing times at night (+21.65 min) and overall (+36.00 min) and remained lying down (ruminating and resting) for longer (+ 73.07 min) than conventional pasture grazing system animals. In addition, the animals in the silvopasture had a lower water intake (3.12 L/100 kg BW). The silvopasture grazing system improved the welfare of the grazing Jersey cows, as evidenced by the improvement in physiological response to heat stress, increased grazing time and decreased standing time (resting + ruminanting) when compared to cows in the conventional pasture grazing system.

Comparative Dynamics of Above-Ground Litter Production and Decomposition from Eucalyptus grandis Hill ex Maiden and Pinus taeda L., and Their Contribution to Soil Organic Carbon

The replacement of native pasture by exotic commercial forest species is an infrequent situation worldwide. In these systems, a new component is introduced, forest litter, which constitutes one of the main ways of incorporating carbon into the soil–plant system. The present work seeks to establish a methodological approach to study the dynamics of litter production and decomposition in an integrated way. The general objective was to characterize and compare the litter production dynamics in 14-year-old Eucalyptus grandis Hill ex Maiden and Pinus taeda L. commercial plantations. During two years, seasonal evaluations of fall, decomposition and accumulation of litter were carried out in stands of both species. In turn, the contribution of carbon from forest species to the soil through isotopic analysis techniques was quantified. Litterfall in E. grandis showed maximums during the spring of the first year and in the spring and summer of the second. In P. taeda, the maximums occurred in summer of the first year and in autumn of the second. In relation to the decomposition rate, the results based on short periods of evaluation between 15 and 21 months did not show differences between species, nor for the different moments of beginning of the evaluation, obtaining average values of 0.0369 month−1 for E. grandis and 0.0357 month−1 for P. taeda. In turn, both the decomposition rate of the material as a whole and the estimates of accumulated biomass in equilibrium state did not show significant differences between the species. Additionally, there was a relevant incorporation of carbon into the soil by forest species, fundamentally in the first few centimeters, substituting an important proportion of the carbon inherited by the original cover of native pastures. Finally, it is necessary to specify that the scope of the findings obtained is greatly limited by the sample size used in this study.

Effect of substrates of native and exotic plant species on the initial period of colonization of benthic macroinvertebrates in the Cerrado biome

The introduction of exotic species can generate changes in the composition of organic debris of alien origin in aquatic ecosystems close to the places of introduction. This new debris can cause impacts at the level of communities and ecosystems. Therefore, the present work aims to answer the following question: are the macroinvertebrate communities present in substrates formed by leaves of the exotic species Pinus caribaea Morelet (Pinaceae) and Eucalyptus grandis Hill ex Maiden (Myrtaceae) similar to those found in substrates composed by the mix of these two species and substrates composed by a mix of native species? For the collection of macroinvertebrates, sets of four types of artificial substrates were submerged in a stream inside the Ecological Station of Panga (Uberlândia—MG, Brazil). The treatments were: leaves of P. caribaea, leaves of E. grandis, leaves of both exotic species and leaves of two native species. In the 20 sample units, about 250 individuals were found, belonging to the orders Coleoptera, Diptera, Ephemeroptera, Heteroptera, Megaloptera, Odonata, Plecoptera and Trichoptera. The effects of the treatments were observed in the exponential decay of the substrate mass and in the structure of the benthic macroinvertebrates communities. The composition of these communities differed among treatments, with high dissimilarity observed between P. caribaea treatments and the mix of exotic species. Therefore, the results demonstrate the importance of substrate complexity for benthic macroinvertebrates, as well as the possible effects of biological invasion and co-invasion by species widely used in silviculture activities.

Validation of variants using cost effective highresolution melting (HRM) analysis predicted from target re-sequencing in Eucalyptus

The advent of next-generation sequencing has facilitated large-scale discovery and mapping of genomic variants for high-throughput genotyping. Several research groups working in tree species are presently employing next generation sequencing (NGS) platforms for marker discovery, since it is a cost effective and time saving strategy. However, most trees lack a chromosome level genome map and validation of variants for downstream application becomes obligatory. The cost associated with identifying potential variants from the enormous amount of sequence data is a major limitation. In the present study, high resolution melting (HRM) analysis was optimized for rapid validation of single nucleotide polymorphisms (SNPs), insertions or deletions (InDels) and simple sequence repeats (SSRs) predicted from exome sequencing of parents and hybrids of Eucalyptus tereticornis Sm. ? Eucalyptus grandis Hill ex Maiden generated from controlled hybridization. The cost per data point was less than 0.5 USD, providing great flexibility in terms of cost and sensitivity, when compared to other validation methods. The sensitivity of this technology in variant detection can be extended to other applications including Bar-HRM for species authentication and TILLING for detection of mutants.

HEIGHT-DIAMETER RELATIONSHIPS FOR Eucalyptus grandis HILL EX. MAIDEN IN MOZAMBIQUE: USING MIXED-EFFECTS MODELING APPROACH

Equations express that height-diameter relationships are used to estimate tree heights that were not measured in the plots, as well as to calculate their volumes. In this study, we modelled height for Eucalyptus grandis Hill ex. Maiden stands using nonlinear mixed effect models in Mocuba District, Central Mozambique. Models were tested from 1414 trees measured, in 40 plots with dimensions of 20 x 20 m. Model one (M1) was the best in relation to the others according to the evaluated criteria (R2 = 0.9183; RMSE = 0.558; AIC = -1234.8; BIC = -1224.9). The inclusion of the variables dominant height (h100, m), basal area (G, m2.ha-1) and mean basal area diameter (dg, m) in model 1 (M1) within the scope of mixed effect model structures that involved both fixed and random effect parameters (Model 7) provides better fitting and more precise predictions. For calibration of random effects according to plot, height measurement of at least five trees is required (four dominant trees + one tree randomly selected in plot). Our model is site-specific and its application should therefore be limited to the stands with characteristics that were the basis of this study. Further works on recalibration, validation, and verification of our model using a larger dataset collected from a wider range of species distribution will be more interesting.

Cold acclimation and freezing tolerance in three Eucalyptus species: A metabolomic and proteomic approach

The ability of plants to cope with frost events relies on the physiological and molecular responses triggered by cold temperatures. This process, named acclimation, involves reprogramming gene expression in order to adjust metabolism. Planted Eucalyptus species are highly productive but most of them are frost sensitive. However, acclimation process varies among species and environmental conditions, promoting more or less frost damage in young plantations of frost-prone areas. To identify metabolites and proteins responsible for these differences, two acclimation regimes were imposed to seedling of Eucalyptus grandis Hill ex Maiden (Eg), Eucalyptus dunnii Maiden (Ed) and Eucalyptus benthamii Maiden Cambage (Eb), and leaves submitted to biochemical and molecular analyses. Further, seedlings were used for simulated frosts in order to test the acclimation status effect on frost tolerance. Eb showed higher frost tolerance than Ed and Eg under control and acclimation scenarios, possibly due to its higher accumulation of phenolics, anthocyanins and soluble sugars as well as lower levels of photosynthetic pigments and related proteins. Also, a rise in frost tolerance and in osmoprotectants and antioxidants was observed for all the species due to cold acclimation treatment. Interestingly, metabolic profiles differed among species, suggesting different mechanisms to endure frosts and, probably, different requirements for cold acclimation. Shotgun proteomics reinforced differences and commonalities and supported metabolome observations. An in depth understanding of these responses could help to safeguard planted forests productivity through breeding of tolerant genetic material.

Production costs in the log processing of Eucalyptus spp. wood.

The objective of this study was to evaluate the production costs of processing logs from Eucalyptus grandis Hill ex Maiden and Eucalyptus saligna Sm, using two sawing pattern in a medium-sized sawmill. Alternating tangential sawing pattern was used for logs with a mean diameter of 33.0 cm and the radial sawing pattern for logs with a mean diameter of 47.0 cm. Based on the data obtained in the different sawing pattern, the fixed, variable and total costs were calculated and, subsequently, the average value for each of these costs. For the alternating tangential sawing pattern, the fixed cost represented 19.32% and the variable cost 80.68%. For the radial sawing pattern, the fixed cost represented 18.92% and the variable cost 81.08%. The radial sawing pattern presented lower average production costs, with a difference of 22.89 R$/m³, however there is no significant difference between the sawing pattern.

Cupins subterrâneos associados a plantios florestais na Amazônia Meridional, Brasil

A crescente demanda por madeira está sendo suprida através de plantios florestais homogêneos. No entanto, grandes extensões de cultivo com uma única espécie são suscetíveis a ataques de insetos-praga. Os cupins são uma dessas pragas, capazes de destruir o sistema radicular das plantas e prejudicar seu desenvolvimento. O objetivo do presente estudo foi conhecer a diversidade de cupins subterrâneos presentes em plantios de Eucalyptus urograndis (Eucalyptus urophylla S.T. Blake x Eucalyptus grandis Hill ex Maiden: Myrtaceae), Tectona grandis L.f.: (Lamiaceae) e consórcio de Bertholletia excelsa Humb. & Bonpl. (Lecythidaceae) e Hevea brasiliensis (Willd. ex A. Juss.) Müll.Arg. (Euphorbiaceae) no município de Alta Floresta - MT, além de verificar a distribuição espacial de cupins nesses locais e a influência das condições edáficas na diversidade de espécies nestas áreas. A pesquisa foi realizada com armadilhas de papelão ondulado, que foram removidas após 30 dias da instalação e seus indivíduos foram contados e identificados. Amostras de solo foram coletadas nos plantios para testar a correlação entre as variáveis edáficas e as espécies encontradas. Um total de 14.861 térmitas foram coletados, representando cinco espécies de cupins, sendo aquela com maior ocorrência Heterotermes tenuis (Hagen) (12.802 espécimes). A distribuição espacial de todas as espécies foi agregada. A maioria das armadilhas atacadas foi de classe 2 (apresentando entre 101 e 500 térmitas), e a correlação mostrou significância somente entre a quantidade de argila no solo e H. tenuis. A diversidade de térmitas nos plantios é composta por cinco espécies, e a distribuição agregada indica preferência pelas áreas mais favoráveis do ambiente, com maior ocorrência de H. tenuis em solos argilosos.

Produção de biomassa de <i>Eucalyptus grandis</i> Hill ex. Maiden em diferentes arranjos de espaçamentos de plantio simples e duplos

O objetivo deste trabalho foi avaliar o efeito dos espaçamentos de plantio em linhas simples e duplas na área basal, volume de madeira com casca por hectare, densidade básica do tronco e biomassa arbórea de Eucalyptus grandis Hill ex Maiden (clone G-21) manejado no sistema de curta rotação. O ensaio foi composto por quatro espaçamentos de plantio: 3,0 m × 1,0 m × 2,0 m (linha dupla), 3,0 m × 1,0 m (linha simples), 3,0 m × 1,0 m × 1,0 m (linha dupla) e 3,0 m × 0,5 m (linha simples), sendo avaliado aos 12 meses e 24 meses após o plantio. As principais diferenças significativas foram encontradas no segundo período de avaliação para os fatores de variação considerados – espaçamento e idade. A área basal aumentou com o adensamento das florestas, embora o volume não tenha seguido a mesma tendência aos 24 meses de plantio. A densidade básica aumentou com a idade apenas nos espaçamentos simples. No estudo da alocação de biomassa nos diferentes compartimentos da árvore, verificou-se uma maior proporção de biomassa de tronco com a idade, bem como nos espaçamentos mais adensados. Uma das maiores produções florestais (65 Mg ha-1) foi encontrada no espaçamento 3,0 m × 1,0 m aos 24 meses de idade.