Commercial Eucalyptus Plantations Research Articles

Deciphering the importance of morphological aspects in drought tolerance in eucalyptus progenies

Water limitation is one of the factors that most impact plant growth and productivity, especially for Eucalyptus. For commercial eucalyptus plantations to develop properly, it is essential to select clones with drought-tolerant characteristics, especially in areas with low rainfall and well-defined dry periods. Accordingly, climate change, mainly related to increases in mean annual temperature, can lead to a more severe water deficit and ultimately harm plant development. Thus, the identification of indicators related to climatic variables enables the selection of clones with drought tolerance characteristics. Here, we used 27 families of eucalyptus progenies from crosses of plants with previously selected characteristics associated with drought tolerance, which were planted in a region characterized by high water deficiency. Sample harvesting was performed at 6, 18, and 30 months after planting, at the end of natural drought cycles. Meteorological data coupled with physiological analyses allow the early selection of Eucalyptus clones that are better able to tolerate recurrent drought events. Specific leaf area (SLA), leaf area (LA), length (L), width (W), and leaf water potential (ΨL) were analyzed. The parameters SLA, LA, and ΨL proved to be good bioindicators of Eucalyptus drought tolerance. Specific clones and progenies (e.g., GG2673, VM1, GG1923, GG1980, GG3389XGG4302, GG918XVS62, AEC2034xLR831, I3000XVM1, VM4XCAM, and VM1xVM4) were characterized by physiological adjustments and showed higher average annual volumetric increment (IMAvol) values and were assumed as genetic materials with potential drought tolerance.

Environmental Impacts of Mechanized Timber Harvesting in Eucalyptus Plantations in Brazil

The advancement of mechanization in forestry has increased productivity in the forestry sector, bringing positive and negative impacts that require a deeper understanding for sustainable forest management. This study aimed to apply a simplified instrument for assessing damage and environmental impacts in forest harvesting of commercial eucalyptus plantations, using a combination of methodologies. The methodology used combined interaction networks and impact assessment matrices, carrying out field surveys, transposing them to interaction networks and weighting them through assessment matrices, resulting in environmental indices (ES) for prioritizing actions. The study was conducted on a commercial eucalyptus plantation in the municipality of São Pedro, São Paulo, Brazil. The mechanized harvesting of the area consists of the structure of a module with a mobile unit consisting of a harvester and forwarder. The results indicated that wood transport presented the highest ES, both positive and negative. The most significant negative impacts (ES) were the depletion of water resources and erosion, while the positive impacts included regional development and job creation. The most notable changes, positive and negative, were observed in the physical and anthropic environment, with a lesser impact on the biotic environment.

Detection of Arsenophonus in Glycaspis brimblecombei (Hemiptera: Aphalaridae) populations in Brazil.

Eucalyptus is the most intensively managed tree genus in the world. Different factors, including damage by insect pests, affect its growth and productivity. Among these pests is Glycaspis brimblecombei Moore (Hemiptera: Aphalaridae), an exotic insect of Australian origin. The evolutionary success of this insect depends on symbiotic associations with microorganisms. The influence of these microorganisms on insect pests and their natural enemies is important for integrated management tactics. Within this context, this work aimed to detect Arsenophonus in populations of G. brimblecombei in Brazil. Eucalyptus branches infested with G. brimblecombei nymphs were collected in commercial eucalyptus plantations in six Brazilian states. Specimens of this pest were sampled soon after emergence and frozen for molecular analysis. The genomic DNA of G. brimblecombei adults from each population was extracted and used to detect the endosymbiont Arsenophonus by polymerase chain reaction (PCR) employing specific primers that target its 23S rRNA gene. This endosymbiont was identified in all of the studied G. brimblecombei populations. This is the first report on the association between Arsenophonus and G. brimblecombei in Brazil.

FOREST HARVESTING: HOW MACHINE TRAFFIC CAN AFFECT SOIL COMPACTION VARIABILITY

The forestry sector has seen an increase in wood demand in recent years, requiring greater mechanization and sustainability in forestry operations, operational excellence, and productivity of stands. The effect of harvesting machine traffic on the soil alters its physical properties, causing degradation, soil compaction, and reducing the volumes of wood produced by commercial forests. Thus, the objective of the present study was to evaluate the spatial variability of soil physical attributes after harvesting and skidding operations, carried out by a harvester and forwarder respectively, in a commercial eucalyptus plantation. The study was conducted in two areas in the municipalities of Itanagra-BA and Entre Rios-BA. Samples were collected in three layers (0-0.20 m; 0.20–0.40 m; 0.40–0.60 m) and the following items were evaluated: total porosity, bulk density, and soil penetration resistance. Operations performed by the harvester and forwarder altered soil resistance, with a greater effect on sandy loam soils, decreasing their density and porosity. Regarding the number of forwarder passes, the seventh pass generated the peak resistance, altering soil recovery capacity, causing additional compaction. Operational planning, to reduce the effects of compaction in areas most susceptible to physical soil degradation, is essential in the forestry area, especially when moisture values are high, a factor that favors soil compaction and reduces stand productivity.

Analysis of the commercial eucalyptus plantation sector in Uruguay from a macroeconomic perspective

The Uruguayan forest sector has developed based on commercial pine and eucalyptus plantations. This process has been based on the installation of vertically integrated companies, with foreign capital and some local capital, investment funds and medium and small industries. In addition to these groups, there are contractor companies in which several of the activities of the primary sector are outsourced, as well as some of the industry. Investment attraction factors are diverse and related not only to productive conditions, e.g., growth rates, but also to institutional conditions, e.g., macroeconomic stability. With the development of the forest sector, there is currently a preponderance of eucalyptus plantations over pine plantations. This characteristic has implications in terms of the products to be obtained and, therefore, the industries to be developed, and the markets to be accessed. The presentation analyzes the evolution of the participation of the forest sector in Uruguay's macroeconomy, considering its share in the country's exports as well as in international trade, with emphasis on the products obtained from eucalyptus plantations. The scope and limitations of the available data for Uruguay are considered. Finally, the importance of including the value of ecosystem services provided by the forest in the traditional macroeconomic valuation is discussed. Results show that Uruguay has an important participation in non-coniferous wood markets. According to FAO data, in 2022, Uruguay's production ranked 8th among non-coniferous pulpwood producing countries, after Chile, up one place from the previous year. The same year Uruguay ranked 10th in terms of production of bleached wood pulp. Furthermore, it is expected that the wood pulp will increase with the new operations of the third pulp mill. Furthermore, cellulose pulp ranked 3rd among Uruguay's export products in 2022, after beef and soybeans, and 2nd in the previous year. The results of this research are of interest to potential investors in the Uruguayan forest sector as well as to policymakers. Potential investors in the Uruguayan forest sector may find insights into the industry's growth potential. Policymakers can use this information to make informed decisions that support the development and regulation of the sector for the benefit of both the economy and the environment.

Estimated volume of eucalyptus plantations through ALOS satellite images

Estimates of wood volume, either in even or uneven-aged forests, is necessary for planning forest management, studies concerning carbon sequestration and natural resources conservation, as well as energy planning in regions where wood is the primary fuel for power generation. Such purposes mainly involve analysis of large areas, which leads to challenges that can be solved through remote sensing. Using multispectral and microwave data, respectively, from the AVNIR-2 and PALSAR sensors, both on board in the ALOS satellite, the wood volume of a commercial eucalyptus plantation located in the state of Minas Gerais, Brazil was estimated using artificial neural. Neural networks emerged as a powerful machine learning technique, capable of modeling intrinsically nonlinear relationships that are present in the data. Thus, the obtained estimates for wood volume in the eucalyptus plantations showed a correlation coefficient with the corresponding observed volumes (forest inventory) of 0.99, a square root of the quadratic error (RQEM) of 0.3% and errors with amplitude between -1 to 1%. The efficiency of artificial neural networks for estimating wood volume in homogeneous plantations has been proven. The multilayer perceptron neural network was efficient in modeling the complex relationships that exist between multispectral, microwave and wood volume data, producing highly accurate estimates. Only a small amount of plots was sufficient to train the artificial neural networks in order to estimate volume. In addition, the fast convergence obtained by the BFGS algorithm allowed a comprehensive data analysis.

Decision-Tree Application to Predict and Spatialize the Wood Productivity Probabilities of Eucalyptus Plantations

Brazil is one of the world’s wood short-fiber producers, cultivating 7.5 million hectares of eucalypt trees. Foresters and resource managers often face difficulties in surveying reliable Eucalyptus productivity levels for the purpose of purchasing and prospecting lands. Spatial data science (DS) and machine learning (ML) provide powerful approaches to make the best use of the large datasets available today. Agriculture has made great use of these approaches, and in this paper, we explore how forestry can benefit as well. We hypothesized that both DS and ML techniques can be used to improve Eucalyptus productivity zoning based on multiple operational datasets of tree growth and environment. Based on more than 12,000 permanent forest inventory plots of commercial Eucalyptus plantations and the climate, soil, and altitude variables associated with them, a supervised ML approach was adjusted to model the forest plantation productivity. A multi-tuning of the decision-tree (DT) algorithm hyperparameters was prepared to yield 450 DT models, with a better one delivering an RMSE of 53.5 m3 ha−1, split in 35 terminal nodes, here interpreted as Eucalyptus productivity zones. The DT model showed an optimum performance index of 0.83, a coefficient of determination of 0.91, a root mean squared error of 12.3 m3 ha−1, and a mean absolute percentage error only of 3.1% in predicting the testing dataset throughout the study area. The DT rule set was interpreted in a user-friendly table and was prepared to classify any location within the study area in each one of the 35 productivity zones based on the required environment variables of the DT algorithm. The high quality of the model obtained made it possible to spatialize the DT rules, providing a reliable cartographic visualization of the probability levels of true Eucalyptus productivity for a huge region of forest-based industries in Brazil. These data-science techniques also provided a yield gap analysis using a very down-to-earth approach. We estimated a yield gap by an amount of 4.2 × 107 m3, representing a few more than 113,000 ha, or 15% of the current forest base. This is the amount of avoided area expansion to accumulate the same wood stock in case the productivity is raised to the attainable level in each zone. This present study provided deeper analysis and reproducible tools to manage forest assets sustainably.

Post-Harvest Eucalyptus Residue Removal Reduces Soil Aggregation and Biological Activities in Central-West Brazil

Tree residue removal from Eucalyptus plantations after timber harvest can reduce soil functioning by reducing the organic matter input. To assess the effects of residue management systems (RMS) on soil aggregation, carbon (C) and nitrogen (N) content, and biological activities, a field trial was conducted in a commercial Eucalyptus plantation (loamy sand soil) in Mato Grosso do Sul, Brazil. The study assessed three RMS: cut-to-length (CTL), tree-length (TL), and bare litter (BL), respectively. After 21 months, undisturbed soil samples were collected and physically isolated into three aggregate-size fractions: large macroaggregates (LM), medium macroaggregates (SM), and microaggregates (MI). Results showed that these soils are mostly composed of LM (54%), and that removing harvest residues from the growing site included total organic carbon (TOC) by 28%, microbial biomass-C by 20%, fluorescein diacetate hydrolysis by 17%, and β-glucosidase activity by 26%, when compared to CTL. TL outperformed CTL for the proportion of LM and LM-associated TOC. Across fractions, a higher microbial quotient was observed in SM and MI fractions, suggesting that the TOC has higher stability inside the LM. This study suggests that leaving harvest residues on the soil should be recommended for Eucalyptus plantations, especially in low-fertility sandy soils, as it helps in maintaining the soil structure and biological activities critical for soil health and ecosystem function.

"Biology of the invasive shell lerp psyllid, Spondyliaspis cf. plicatuloides (Froggatt) (Hemiptera: Aphalaridae)"

Spondyliaspis cf. plicatuloides (Froggatt) (Hemiptera: Aphalaridae) is native to Australia but was first detected outside its native range in 2014, in South Africa. It feeds on eucalypt species and thus has the potential to become a pest in commercial Eucalyptus plantations. Information on the basic biology of this insect, which is important for the development of surveillance and management strategies, is lacking. To investigate the life cycle and general biology of S. plicatuloides, the psyllid was reared under controlled glasshouse conditions on potted red-flowering gum, Corymbia ficifolia. The egg incubation period, number of nymphal instars and their developmental time, adult fecundity, adult longevity and duration of the life cycle were determined. The major diagnostic features used to differentiate the five nymphal instars were the number of antennal segments, wing pad development and body length. Females reached reproductive maturity 2.3 ± 0.47 (mean ± SD) days after eclosion and laid 16.2 ± 3.9 (mean ± SD) eggs on average. Reproduction was sexual. The first nymphal instar took 10.7 ± 1.2 (mean ± SD) days to hatch from the egg. The nymphal instars completed their development in 22.6 ± 1.4 (mean ± SD) days under the brown scalloped shelters they secrete. The insect's total life cycle lasted 37.37 ± 1.17 (mean ± SD) days from egg to adult death. Males and females lifespan is also reported. The study provides the first information on the basic biology of S. cf. plicatuloides that will be useful for future studies on surveillance and management strategies.

Commercial Eucalyptus Plantations with Taungya System: Analysis of Tree Root Biomass

The increasing demand for wood, fiber, and pulp, coupled with efforts to mitigate greenhouse gas emissions, has placed immense importance on the development of forest plantations. The rapidly growing human population faces shortages of food, particularly in the developing world where agricultural productivity is generally low. The taungya system, an age-old agroforestry practice involving the intercropping of crops with trees on the same unit of land, is opined as a win-win strategy to meet the need for wood products and food at the same time. In recent years, the taungya system has gained increasing attention from large forest companies as a tool and an opportunity to contribute to the social well-being of the local community. However, the effects of intercropping on the tree component are largely unexplored. Thus, this study was conducted to examine whether intercropping after 2 and 7 years has an effect on the root system of trees, thereby generating knowledge that supports evidence-based plantation management decisions involving the taungya system. To characterize the root system architecture, trenches were made on six young trees in both a pure Eucalyptus camaldulensis monoculture and intercropped stands (1111 trees/ha in both stands). To quantitatively estimate root biomass, a total of 324 soil cores (6 stands × 6 trees × 3 distances × 3 soil depths) were collected, and roots were sorted and dried to constant mass in an oven at 60 °C for 48 h. The root dry mass data were subjected to analysis of variance to examine the significant effects of intercropping, spacing, and stand age. The results show that the root system of E. camaldulensis was mainly confined to shallow depth but well elongated horizontally in both pure and intercropped stands with 4–6 thick lateral roots. The intercropping of rice/cassava with eucalypt had no effect on the total root dry mass of the tree component (p > 0.05) irrespective of the plantation spacing (5 m × 2 m or 9 m × 1 m); however, root biomass decreased with increasing horizontal distance from the tree base and in deeper soil layers, particularly for trees in young stands. The effects of spacing between trees, wide (5 m × 2 m) versus narrow (9 m × 1 m), on root dry mass were dependent on the horizontal and vertical distribution of the root system, and root biomass appeared to be higher at 40 cm soil depth for the stand with wide spacing between trees than for stands with narrow spacing. Root biomass was larger for older rather than younger trees in both monoculture and intercropped stands, suggesting the lack of a carry-over effect of intercropping on root biomass. In conclusion, this study provides evidence in support of intercropping as a win-win strategy to meet the short-term needs of food production while producing wood in the end. As root biomass varies with horizontal distribution, further research is recommended to test buffer zones between trees and crops other than 1m, which is currently used.

Implementation and calibration of short-rotation eucalypt plantation module within the ECOSMOS land surface model

Eucalypt is one of the most-planted broadleaf genera around the globe, exhibiting high yield, plasticity and growing capacity on a broad range of environments. The main objective of this study is to present the integration of a specific module for eucalypt short-rotation plantations into ECOSMOS (Ecosystem Model Simulator). Different calibrations and validations, from intensively monitored sites, experimental networks, and plots in commercial stands were performed. We calibrated all ECOSMOS model biophysical and physiological parameters for the Eucalyptus module using three micrometeorological experiments. A generic genotype was calibrated and applied to evaluate the model performance in response to contrasting environments and genotypes, on a dataset from an experimental network with high Genotype x Environment interactions. The model was applied over commercial eucalypt plantations sites, where re-calibration was necessary for four parameters of the ECOSMOS-Eucalyptus module related to leaf carbon allocation and specific leaf area, because of significant differences in genotypes and management among datasets. Results showed the consistency of the biophysical and physiological processes solved by the model, simulated energy and carbon fluxes, soil water dynamics, and growth of different plant components when compared with observations; Nash-Sutcliffe efficiency (NSE) of 0.93, 0.43 and 0.27 for net radiation, net ecosystem exchange and evapotranspiration, respectively were obtained for the validation dataset. The generic genotype calibration varied greatly in simulating the eucalypt stem growth of the 26 locations. The generic calibration can be used as reference for eucalypt plantation’ areas in Brazil; however, a re-calibration is recommended for operational applications to adjust the ECOSMOS-Eucalyptus module to the management conditions, management practices and genotypes used by companies.

Two new species of Calonectria (Hypocreales, Nectriaceae) causing Eucalyptus leaf blight in Brazil.

In recent decades, commercial Eucalyptus plantations have expanded toward the warm and humid regions of northern and northeastern Brazil, where Calonectria leaf blight (CLB) has become the primary fungal leaf disease of this crop. CLB can be caused by different Calonectria species, and previous studies have indicated that Calonectria might have high species diversity in Brazil. During a disease survey conducted in three commercial plantations of Eucalyptus in northeastern Brazil, diseased leaves from Eucalyptus trees with typical symptoms of CLB were collected, and Calonectria fungi were isolated. Based on phylogenetic analyses of six gene regions (act, cmdA, his3, rpb2, tef1, and tub2) and morphological characteristics, two new species of Calonectria were identified. Five isolates were named as C.paragominensis sp. nov. and four were named as C.imperata sp. nov. The pathogenicity to Eucalyptus of both species was confirmed by fulfilling the Koch's postulates.

Nutrient use efficiency in commercial eucalypt plantations in different soils under temperate climate

The sustainability of forest production is based on an adequate balance between soil nutrient supply and its demand by forest plantations, which may vary depending on the species and the site. In Uruguay, the low to medium fertility of the soils under forest production makes this aspect relevant. The objectives of the study were: (a) to quantify the concentration and distribution of nutrients in the harvested biomass of Eucalyptus dunnii, Eucalyptus grandis and Eucalyptus globulus in the predominant soils of the zones of greater forestry aptitude of Uruguay; and (b) to compare the nutrient use efficiencies of the three mentioned species in different soil types, as a criterion to evaluate the sustainability of the productive system in the long term. In 29 sites located in the three main forest areas of the country, nine trees with average diameter at breast height (DBH) and height were harvested at eight to eleven years of age. The aerial biomass and nutrient uptake (nitrogen, phosphorus, potassium, calcium and magnesium) in commercial wood, bark, leaves and branches were quantified, and two nutrient use efficiency indexes (nutrient use efficiency and biological utilisation coefficient) were calculated. Although the zones offered different conditions for growth and nutrient uptake, E. dunnii presented the highest extraction of nutrients in commercial wood, considering all sites, these indexes being lower for E. dunnii. Therefore, when planting E. dunnii, its greater use of the soil’s resources must be considered, particularly in soils that are naturally less fertile. Likewise, E. grandis presented a greater extraction of cations than E. globulus because of more extensive growth.

GESTÃO DA EXTRAÇÃO FLORESTAL COM O INDICADOR EFICIÊNCIA GLOBAL DE MÁQUINAS FLORESTAIS (EGMF)

ABSTRACT Performance indicators are tools capable of exposing measurable characteristics and generating relevant information on forest operations, thus being considered pillars for managers to make agile and assertive decisions. Forest extraction with a forwarder must be improved, understanding the factors that affect the costs of this machine, such as productivity (PR), fuel consumption (FC), operational efficiency (OE), and quality of operation. Thus, the objective of this study was to evaluate the implementation of the Overall Efficiency of Forest Machines (OEFM) indicator in the management of forest extraction data using forwarders. Data were collected during forest harvesting from five operating fleets, in commercial eucalypt plantations, in full-tree and coppice regimes, in the states of Bahia and Espírito Santo. The indicator was expressed as a percentage calculated by OEFM = ( ( 4 ∗ PR ) + ( 3 ∗ FC ) + ( 3 ∗ OE ) ) / 10. The performance of the machines was evaluated by a stochastic model of dynamic simulation of systems in eight scenarios, proposing improvement for the average individual volume harvested, fuel consumption, and mechanical or operational stops. Analyzes were performed using PowerSim Studio 9 software. The OEFM of two fleets was higher than the established target of 95.17%, with 95.72% and 97.44%. The OEFM indicator proved to be useful in the management of forest extraction with adequate and easy-to-understand information from a large amount and variety of data. The stochastic simulation model was efficient to study the impact on the global efficiency and the flow of wood extraction by the forwarder.

Very Low Nutrient Losses by Deep Leaching after Clearcutting Commercial Eucalyptus Plantations in Brazil

Very Low Nutrient Losses by Deep Leaching after Clearcutting Commercial Eucalyptus Plantations in Brazil

Como mudanças climáticas globais podem influenciar na distribuição geográfica do besouro amarelo do eucalipto? Modelagem e predição para o Brasil

Abstract Popularly known as the yellow eucalyptus beetle, Costalimaita ferruginea (Fabricius, 1801) (Coleoptera: Chrysomelidae), in the adult phase it feeds on the leaves of the myrtaceae, leaving them laced, a fact that impairs the productivity of plantations. Therefore, this work aims to model the potential distribution of the beetle in climate change scenarios for Brazil. The biotic data were collected through a review of the literature and entomological collections, totaling 88 georeferenced points of occurrence of the insect in the country. The abiotic data (19 biovariables, precipitation and minimum, average and maximum temperature) in the Wordcllim database, represent the periods: current (1970-2000), middle (2041-2060), and final (2061-2080) of the century, with representation in two projections of climatic anomalies (RCP 4.5 and RCP 8.5). To determine the most important variables for the models, the Jackknife test was performed in the Maxent software, which resulted in five biovariables, namely: annual precipitation (35.2%), temperature seasonality (15.2%), annual temperature variation (13.7%), seasonality of precipitation (8.7%) and an average temperature of the coldest quarter (7.4%). Subsequently, the Openmodeller software was used and five algorithms were tested to determine which model represents the prediction of areas of suitability for the occurrence of the insect. The algorithm that best represented the appropriate areas was the Envelope Score (AUC = 0.808), corroborating the occurrence data collected. The prediction shows that the Pampa biome, in the RCP8.5 scenario for the period between 2061-2080, will become fully suitable for the occurrence of this defoliator beetle, unlike the Amazon, which presents retraction in areas suitable for the occurrence of the beetle for the same period. In this sense, commercial eucalyptus plantations implemented in climatologically suitable areas for the occurrence of this insect must be monitored periodically.

First record of a new microsporidium pathogenic to Gonipterus platensis in Brazil

Microsporidia are naturally occurring fungal-related parasites that can infect nearly all animal hosts, but their biocontrol potential of insect pests is routinely overlooked in agriculture and forestry. This research brings the first report describing the natural occurrence of a microsporidium causing disease in field-collected populations of the invasive eucalyptus snout beetle, Gonipterus platensis (Coleoptera: Curculionidae), a major destructive pest of eucalyptus plantations in Brazil. Adult beetles were collected during field surveys in commercial eucalyptus plantations in southern Brazil to be examined and dissected with typical symptoms to verify presence of microsporidian spores in haemolymph. From 14 plantations in different sites, the natural infection occurrence in these populations ranged from 0 to 65%, while a lab colony exhibited an infection incidence of 70%. Spore density in haemolymph of symptomatic insects averaged 2.1 (± 0.4) × 107 spores/beetle. Symptoms in infected adults were identified by an abnormal abdomen with malformation of the second pair of wings, impairing their flight activity. Electron transmission microscopy of the pathogen showed morphological features similar to species belonging to the genus Nosema or Vairimorpha. Phylogenetic analysis of the full-length small subunit ribosomal RNA gene suggests this pathogen’s placement in the genus Vairimorpha, but with a sequence identity of ~ 94% with the nearest neighbours. The low level of sequence identity suggests this pathogen may represent a novel taxon in the genus and further requires whole genome sequencing for definitive taxonomic resolution. These findings provide insights on the natural occurrence of this novel pathogen of this invasive pest in Eucalyptus plantations in Brazil. Further studies are needed to determine potential of this microsporidium in the design of conservative or augmentative biological control programs for this invasive pest.

Variability in soil physical–chemical properties along the root-explored profile in deep Oxisols of commercial eucalypt plantations

While deep soils commonly characterize tropical forests, direct measurements of soil physical–chemical properties, fine root distributions, and relationships among them are scarce. In this paper, we report results from a project in Brazil that were obtained from experimental areas selected for their representative tropical climatic and edaphic features. Our objective was to evaluate vertical and spatial soil physical–chemical properties along the root-explored profile of Eucalyptus plantations to better understand the relationship between each component. Soil was collected from four sites (Três Lagoas-Site 13, Mogi Guaçu-20, Telemaco Borba-22, and Bocaiuva-30) and characterized for physical–chemical properties (pH, texture, organic matter, cation exchange capacity, and nutrient content) and fine root density (FRD). Soil was sampled up to 2 m beyond the deepest observed roots, or until a cemented horizon or R layer was detected. Spatial variability was investigated through a geostatistical approach using ordinary kriging. Data were subjected to ANOVA as well as bi- and multivariate statistics using a correlation matrix and robust principal factor analysis (PFA), respectively. Results showed that investigated Oxisols reached the maximum depth of 19 (Site 13), 8 (20), 11 (22), and 8 (30) m. In most investigated sites (20, 22, and 30) and for most soil properties, a typical soil horizonation was observed along the first 2.5/3.0 m. Deeper horizons (>3.0 m) of clayey Oxisols were characterized by the presence of typical porthole shapes dramatically interrupting soil horizonation, indicating spatial pedovariability and demonstrating underestimates of vertical and spatial pedovariability can occur under standard soil investigations to 2.0 m in depth. Correlation matrix and PFA showed that Eucalyptus roots strongly affected most investigated soil properties. Our study considered vertical and spatial dimensions of soil physical–chemical properties as well as the deep-rooting properties of Eucalyptus, which is critical for improving soil management in infertile Eucalyptus plantations.

Occurrence of Calonectria leaf blight in Eucalyptus benthamii progenies and potential for disease resistance

Leaf blight caused by the fungi of the genus Calonectria represents a high economic risk for forestry companies due to the high potential of economic damage to commercial eucalyptus plantations. An outbreak of leaf blight was observed in Eucalyptus benthamii progeny in three sites in Southern Brazil. This study aimed to: (i) identify the causal agents of the disease; (ii) quantify the incidence and severity of leaf blight (CLB), and (iii) evaluate the selection for CLB resistance potential of E. benthamii. The incidence of the disease was 100% and severity progressed over time, causing more than 50% of canopy defoliation in most trees. The fungal species associated with this study were C. metrosideri and C. spathulata, both found to be pathogenic; C. spathulata was the most aggressive. Infection of E. benthamii by these fungi was associated with temperatures around 18 °C and relative humidity of approximately 74%. There is sufficient genetic variability for the selection of resistant E. benthamii progenies to CLB, based on low severity degrees.

Network Analysis Combining Proteomics and Metabolomics Reveals New Insights Into Early Responses of Eucalyptus grandis During Rust Infection.

Eucalyptus rust is caused by the biotrophic fungus, Austropuccinia psidii, which affects commercial plantations of Eucalyptus, a major raw material for the pulp and paper industry in Brazil. In this manuscript we aimed to uncover the molecular mechanisms involved in rust resistance and susceptibility in Eucalyptus grandis. Epifluorescence microscopy was used to follow the fungus development inside the leaves of two contrasting half-sibling genotypes (rust-resistance and rust-susceptible), and also determine the comparative time-course of changes in metabolites and proteins in plants inoculated with rust. Within 24 h of complete fungal invasion, the analysis of 709 metabolomic features showed the suppression of many metabolites 6 h after inoculation (hai) in the rust-resistant genotype, with responses being induced after 12 hai. In contrast, the rust-susceptible genotype displayed more induced metabolites from 0 to 18 hai time-points, but a strong suppression occurred at 24 hai. Multivariate analyses of genotypes and time points were used to select 16 differential metabolites mostly classified as phenylpropanoid-related compounds. Applying the Weighted Gene Co-Expression Network Analysis (WGCNA), rust-resistant and rust-susceptible genotypes had, respectively, 871 and 852 proteins grouped into 5 and 6 modules, of which 5 and 4 of them were significantly correlated to the selected metabolites. Functional analyses revealed roles for photosynthesis and oxidative-dependent responses leading to temporal activity of metabolites and related enzymes after 12 hai in rust-resistance; while the initial over-accumulation of those molecules and suppression of supporting mechanisms at 12 hai caused a lack of progressive metabolite-enzyme responses after 12 hai in rust-susceptible genotype. This study provides some insights on how E. grandis plants are functionally modulated to integrate secondary metabolites and related enzymes from phenylpropanoid pathway and lead to temporal divergences of resistance and susceptibility responses to rust.