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1.
Nature ; 597(7876): 366-369, 2021 09.
Artigo em Inglês | MEDLINE | ID: mdl-34526704

RESUMO

Southeast Australia experienced intensive and geographically extensive wildfires during the 2019-2020 summer season1,2. The fires released substantial amounts of carbon dioxide into the atmosphere3. However, existing emission estimates based on fire inventories are uncertain4, and vary by up to a factor of four for this event. Here we constrain emission estimates with the help of satellite observations of carbon monoxide5, an analytical Bayesian inversion6 and observed ratios between emitted carbon dioxide and carbon monoxide7. We estimate emissions of carbon dioxide to be 715 teragrams (range 517-867) from November 2019 to January 2020. This is more than twice the estimate derived by five different fire inventories8-12, and broadly consistent with estimates based on a bottom-up bootstrap analysis of this fire episode13. Although fires occur regularly in the savannas in northern Australia, the recent episodes were extremely large in scale and intensity, burning unusually large areas of eucalyptus forest in the southeast13. The fires were driven partly by climate change14,15, making better-constrained emission estimates particularly important. This is because the build-up of atmospheric carbon dioxide may become increasingly dependent on fire-driven climate-carbon feedbacks, as highlighted by this event16.


Assuntos
Dióxido de Carbono/análise , Imagens de Satélites , Incêndios Florestais/estatística & dados numéricos , Atmosfera/química , Austrália , Teorema de Bayes , Monóxido de Carbono/análise , Mudança Climática , Eucalyptus , Florestas , Pradaria , Incerteza
2.
J Environ Manage ; 299: 113676, 2021 Dec 01.
Artigo em Inglês | MEDLINE | ID: mdl-34526275

RESUMO

During the past few decades, commercial silvopastoral systems (SPS) with exotic Eucalyptus (hybrid) trees have become popular in the Brazilian Cerrado (savanna). With the increasing awareness about the role of carbon (C) storage in soils as a climate-change mitigation strategy and the relationship between the nature of soil aggregates and the soil's carbon sequestration potential, it is important to understand the influence of such SPS systems on soil organic carbon (SOC) storage. We studied C content in three aggregate size classes in six land-use systems on Oxisols in Minas Gerais, Brazil. The systems were planted forest, native secondary forest, managed pasture, and three 8-year-old SPS, differing in their tree-planting configurations. Eucalyptus hybrid was the tree in SPS and planted forest treatments, and Urochloa decumbens was the grass in SPS and pasture treatments. From each treatment, replicated soil samples were collected from four depth-classes (0-10, 10-30, 30-60, and 60-100 cm), fractionated by wet sieving into the three aggregate-size classes, 2000 to 250 µm, 250 to 53 µm, and <53 µm size classes representing macroaggregates, microaggregates, and silt + clay, respectively, and their C contents determined. Down to 1 m, total SOC stock values ranged from 260 Mg ha-1 under pasture to 167 Mg ha-1 under native forest, with 174 Mg ha-1 for Eucalyptus plantation and about 195 Mg ha-1 for the three SPS. Compared to the degraded native forest, the pasture system had significantly higher SOC in the whole soil and the aggregate size fractions, especially in the lower soil-depth classes. The lower SOC stock of Eucalyptus hybrid SPS compared to open pasture differs from the general trend of SPS having higher stock. Given that the Cerrado biome is a biodiversity hotspot, the use of native nitrogen-fixing trees, of which there are several, is worth investigating. In addition, the conversion from Eucalyptus monocultures to SPS could be considered as a strategy to increase the SOC stock.


Assuntos
Eucalyptus , Solo , Agricultura , Biodiversidade , Carbono , Sequestro de Carbono
3.
An Acad Bras Cienc ; 93(suppl 3): e20201351, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-34468491

RESUMO

Obesity is a major risk factor for type 2 diabetes mellitus development and is characterized by an abnormal expansion of adipose tissue and low-grade chronic inflammation that contribute to insulin resistance. Although there are multiple treatments, most therapies can produce undesirable side effects and therefore, new and effective treatments with fewer side effects are necessary. Previously, we demonstrated that a natural extract from the leaves of Eucalyptus tereticornis (OBE100) has anti-inflammatory, hypoglycemic and hypolipidemic activities. The major compounds identified in OBE100 were three pentacyclic triterpenoids, ursolic acid, oleanolic acid, and ursolic acid lactone. Triterpenoids have shown multiples biological activities. This current study compared the biological effect produced by OBE100 with five different reconstituted mixtures of these triterpenoids. Different cell lines were used to evaluate cytotoxicity, reactive oxygen species production, inflammatory cytokine expression, glucose uptake induction, leptin and adiponectin expression, and lipid accumulation. OBE100 treatment was the most efficacious and none of the formulated triterpenoid mixtures significantly improved on this. Moreover, OBE100 was less toxic and reduced reactive oxygen species production. Our study showed that the proven beneficial properties of triterpenoids may be enhanced due to the interaction with minor secondary metabolites present in the natural extract improving their anti-inflammatory properties.


Assuntos
Diabetes Mellitus Tipo 2 , Eucalyptus , Resistência à Insulina , Triterpenos , Extratos Vegetais/farmacologia , Triterpenos/farmacologia
4.
Bioresour Technol ; 341: 125757, 2021 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-34411942

RESUMO

Glycolic acid has chemical properties similar to those of formic acid. Therefore, similar to formic acid pretreatment, glycolic acid pretreatment has the separation effect of hemicellulose. In this study, eucalyptus hemicellulose was effectively separated by glycolic acid pretreatment. The effects of glycolic acid concentration, temperature and time on the separation of cellulose, hemicellulose and lignin were investigated. The optimum conditions were acid concentration 5.40%, temperature 140 °C, time 3.0 h. The highest yield of xylose was 56.72%. The recovery rate of glycolic acid was 91%. Compared to formic acid, the yield of xylose increased to 10.33% while that of lignin decreased to 11.08%. It showed high selectivity for hemicellulose separation, yielding 65.48% hemicellulose with 72.08% purity. The depolymerization and repolymerization of lignin were inhibited. The integrity of the cellulose structure was preserved. It provides theoretical support for the fractional separation and high-value transformation of lignocellulosic biomass.


Assuntos
Eucalyptus , Biomassa , Glicolatos , Hidrólise , Lignina , Polissacarídeos
5.
Molecules ; 26(16)2021 Aug 19.
Artigo em Inglês | MEDLINE | ID: mdl-34443612

RESUMO

Eucalyptus leaves (ELE) and willow bark (WBE) extracts were utilized towards the formation of silver nanoparticles (AgNPs(ELE), AgNPs(WBE)). AgNPs(ELE) and AgNPs(WBE) were dispersed in polymer hydrogels to create pHEMA@AgNPs(ELE)_2 and pHEMA@AgNPs(WBE)_2 using hydroxyethyl-methacrylate (HEMA). The materials were characterized in a solid state by X-ray fluorescence (XRF) spectroscopy, X-ray powder diffraction analysis (XRPD), thermogravimetric differential thermal analysis (TG-DTA), differential scanning calorimetry (DTG/DSC) and attenuated total reflection spectroscopy (ATR-FTIR) and ultraviolet visible (UV-vis) spectroscopy in solution. The antimicrobial potential of the materials was investigated against the Gram-negative bacterial strain Pseudomonas aeruginosa (P. aeruginosa) and the Gram-positive bacterial strain of the genus Staphylococcus epidermidis (S. epidermidis) and Staphylococcus aureus (S. aureus), which are involved in microbial keratitis. The percentage of bacterial viability of P. aeruginosa and S. epidermidis upon their incubation over the pHEMA@AgNPs(ELE)_2 discs is interestingly low (28.3 and 6.8% respectively), while the inhibition zones (IZ) formed are 12.3 ± 1.7 and 13.2 ± 1.2 mm, respectively. No in vitro toxicity of this material towards human corneal epithelial cells (HCEC) was detected. Despite its low performance against S. aureus, pHEMA@AgNPs(ELE)_2 could be an efficient candidate towards the development of contact lenses that reduces microbial infection risk.


Assuntos
Lentes de Contato/microbiologia , Eucalyptus/química , Hidrogéis/química , Extratos Vegetais/química , Salix/química , Prata/farmacologia , Antibacterianos/síntese química , Antibacterianos/química , Antibacterianos/farmacologia , Humanos , Nanopartículas Metálicas , Testes de Sensibilidade Microbiana , Prata/química
6.
Food Chem ; 365: 130519, 2021 Dec 15.
Artigo em Inglês | MEDLINE | ID: mdl-34247044

RESUMO

Thermal liquefaction is a conventional method used by beekeepers to liquefy crystallized honey. However, an abusive use of heat may affect its quality, chemical composition and bioactivity. The purpose of this study was to investigate the effect of thermal liquefaction on the quality, chemical composition and antibiofilm properties of eucalyptus honey. Thermal liquefaction (at 45 and 60 °C) did not affect the honey's quality; however, a significant reduction in the reducing capacity, total phenolic content and hydrogen peroxide content was observed. At 60 °C, a significant reduction in the honey's ability to inhibit biofilm formation was observed in Pseudomonas aeruginosa, as well as a reduction in its ability to remove preformed biofilms in both Staphylococcus aureus and Pseudomonas aeruginosa. Structural changes in biofilm architecture caused by honey were not affected by thermal treatment. Therefore, we recommend liquefaction at 45 °C as the most convenient for honey liquefaction without affecting its characteristics.


Assuntos
Eucalyptus , Mel , Antibacterianos/farmacologia , Biofilmes , Humanos , Testes de Sensibilidade Microbiana , Pseudomonas aeruginosa , Staphylococcus aureus
7.
Phytother Res ; 35(9): 5282-5289, 2021 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-34314073

RESUMO

Tyrosyl-DNA phosphodiesterase 2 (TDP2) is a recently discovered DNA repair enzyme that can repair topoisomerase 2-mediated DNA damage, resulting in cancer cell resistance. In this study, two compounds, robustadial A and B, were isolated from a fraction of the ethyl acetate extract of Eucalyptus globulus Labill. fruits based on TDP2 inhibition screening. The biological experiments indicated that robustadial A and B have TDP2 inhibitory activity with EC50 values of 17 and 42 µM, respectively, but no tyrosyl-DNA phosphodiesterase 1 inhibition at 100 µM. Robustadial A showed significant synergistic effects with the anticancer drug etoposide in four human cancer cell lines, non-small cell lung cancer cell line (A549), prostate cancer cell line (DU145), breast cancer cell line (MCF-7), colorectal adenocarcinoma cell line (HCT-116), and chicken lymphoma cell line (DT40), and chicken lymphoma cell line complementation with human TDP2 (DT40 hTDP2) with combination index values ranging from 0.21 to 0.74. This work will facilitate future efforts for the development of robustadial A-based TDP2 selective inhibitors.


Assuntos
Antineoplásicos Fitogênicos/farmacologia , Eucalyptus , Neoplasias , Inibidores de Fosfodiesterase , Animais , Linhagem Celular Tumoral , Galinhas , Proteínas de Ligação a DNA , Eucalyptus/química , Humanos , Neoplasias/tratamento farmacológico , Neoplasias/patologia , Inibidores de Fosfodiesterase/farmacologia , Diester Fosfórico Hidrolases
8.
J Genet ; 1002021.
Artigo em Inglês | MEDLINE | ID: mdl-34282737

RESUMO

Eucalyptus breeding programme mainly aims at increasing productivity associated with wood property traits which are suitable for different end uses. The principal challenge in this endeavor is to combine productivity with industrially relevant wood traits. In the present study, 23 hybrid clones derived from a biparental mapping population of Eucalyptus camaldulensis × E. tereticornis was assessed for six wood property traits across two sites in Tamil Nadu, India. The mean of most of the traits evaluated was consistently higher in Muthupettai, indicating significant site effect. Combined and location-wise analysis indicated additive genetic control of assessed traits. The stability of acoustic velocity in study sites, negligible G × E interaction and significant correlation with dynamic modulus of elasticity (DMoE) implies its use in selecting trees/logs for solid wood properties. Combined analysis of locations revealed low to moderate heritability (0.294-0.439) for all the traits with H2 being highest for cellulose per cent (0.439) followed by acoustic velocity (0.416). Genetic advance was calculated and was the highest for diameter (10.47%) followed by DMoE (9.19%). The two major chemical constituents of wood, namely total lignin and cellulose per cent showed 7.13% and 7.53% advancement in the hybrids. The out-performance of several hybrid clones when compared to the parents for different wood traits reiterates the use of Eucalyptus hybrids in plantation programmes to improve quality of raw material suitable for industrial application.


Assuntos
Eucalyptus/química , Hibridização Genética , Locos de Características Quantitativas/genética , Madeira/genética , Eucalyptus/genética , Índia , Fenótipo , Melhoramento Vegetal , Polimorfismo de Nucleotídeo Único/genética , Madeira/química
9.
Ultrason Sonochem ; 76: 105654, 2021 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-34198128

RESUMO

Antioxidant products present a very high added value and are demanded in the market. The optimization of their extraction is a high-stakes matter for both economic and environmental points of view. Ultrasound extraction has been considered one of the most promising methods, so the relative importance of key parameters may have decisive economic significance. For this reason, different parameters that have influence on the extraction capacity such as ultrasound power, time, temperature, pH and % ethanol in water have been studied to know the relationships between the independent parameters and their influence on the extraction from Eucalyptus globulus leaves. An experimental Box-Behnken factorial design and subsequent analysis by neural networks have been used. The relative influence of each parameter varies according to the nature of the extracted compound. In this regard, the higher capacity of extraction of the selected antioxidant compounds by means of the variation of the operation conditions can be facilitated. For all the studied compounds, temperature has been the most important parameter for their extraction. The relative content (%) of bioactive compounds (terpenes) in the optimized Eucalyptus globulus extract has been performed by GC-MS analysis.


Assuntos
Antioxidantes/isolamento & purificação , Antioxidantes/farmacologia , Eucalyptus/química , Folhas de Planta/química , Ondas Ultrassônicas , Antioxidantes/química , Concentração de Íons de Hidrogênio , Temperatura , Fatores de Tempo
10.
Sci Total Environ ; 794: 148723, 2021 Nov 10.
Artigo em Inglês | MEDLINE | ID: mdl-34217075

RESUMO

Providing a valuable application to the under-utilized solid residue of co-pyrolysis of biomass and plastics could substantially improve economic and environmental sustainability of the process, thereby fostering circular economy. This study focuses on the variation of thermal and physiochemical characteristics of solid char, produced from the co-pyrolysis of waste low-density polyethylene (WLDPE) and Eucalyptus wood with varying pyrolysis temperatures from 300 to 550 °C, residence times of 90-150 min, and relative percentage of 33% and 25% (w/w) WLDPE in the feedstock. The highest values of yield (37%), energy density (1.25) and high heat value (31 MJ/Kg) were observed with the char produced at 300 °C. The physical inhibition caused by the overlaying plastic coating on the surface of the char below 450 °C resulted in the same. However, with the increase in temperature, increase in fuel ratio by 78-79% and fixed carbon content by 68-69% were observed. The highest concentrations of fixed carbon (39%), fuel ratio (0.81) along with the lowest O/C and H/C ratios (0.07 and 0.13) were observed with the chars produced above 450 °C depicting their high degree of carbonization. The fuel value indices of all the chars were > 500 GJ/m3 indicating their suitability as high-quality fuels. Significant influences of residence time and feedstock ratio were also observed on properties of the char. The analysis of variance and principal component analysis also depicted significant variations in the properties of the char produced below and above the temperatures of 450 °C due to the inhibitory and synergetic effects. While the chars produced at 300-350 °C could be used for combustion/co-combustion in coal-fired boilers, chars produced above 450 °C can be opted as household fuel due to their low losses of energy, water vapour, and smoke during combustion.


Assuntos
Eucalyptus , Pirólise , Biomassa , Polietileno , Madeira
11.
Molecules ; 26(12)2021 Jun 08.
Artigo em Inglês | MEDLINE | ID: mdl-34201300

RESUMO

Eight polyhydroxy triterpenoid acids, hederagenin, (4α)-23-hydroxybetulinic acid, maslinic acid, corosolic acid, arjunolic acid, asiatic acid, caulophyllogenin, and madecassic acid, with 2, 3, and 4 hydroxyl substituents, were identified and quantified in the dichloromethane extract of Eucalyptus globulus wood by comparing their GC-retention time and mass spectra with standards. Two other triterpenoid acids were tentatively identified by analyzing their mass spectra, as (2α)-2-hydroxybetulinic acid and (2α,4α)-2,23-dihydroxybetulinic acid, with 2 and 3 hydroxyl substituents. Two MS detectors were used, a quadrupole ion trap (QIT) and a quadrupole mass filter (QMF). The EI fragmentation pattern of the trimethylsilylated polyhydroxy structures of these triterpenoid acids is characterized by the sequential loss of the trimethylsilylated hydroxyl groups, most of them by the retro-Diels-Alder (rDA) opening of the C ring with a π-bond at C12-C13. The rDA C-ring opening produces ions at m/z 320 (or 318) and m/z 278 (or 277, 276, 366). Sequential losses of the hydroxyl groups produce ions with m/z from [M - 90] to [M - 90*y], where y is the number of hydroxyl substituents present (from 2 to 4). Moreover, specific cleavage in ring E was observed, passing from m/z 203 to m/z 133 and conducting other major fragments such as m/z 189.


Assuntos
Eucalyptus/química , Triterpenos/química , Madeira/química , Cloreto de Metileno/química , Extratos Vegetais/química , Espectrometria de Massas em Tandem/métodos
12.
Biotechnol J ; 16(9): e2100030, 2021 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-34102004

RESUMO

Failure in the prevention of cross-transmission from contaminated gloves has been recognized as an important factor that contributes to the spread of several healthcare-associated infections. Ex situ coating process with silver nanoparticles (AgNPs) using Eucalyptus citriodora ethanolic leaf extract as reducing and capping agents to coat glove surfaces has been developed to prevent this mode of transmission. Elemental analysis of coated gloves showed 24.8 Wt% silver densely adhere on the surface. The coated gloves fully eradicated important hospital-acquired pathogens including Gram-positive bacteria, Gram-negative bacteria, and yeasts within 1 h. The coated gloves showed significant reduction, an average of five logs when tested against all standard strains and most clinical isolates (p < 0.01). Following prolonged exposure, the coating significantly reduced the numbers of most adhered pathogenic species, compared with uncoated gloves (p < 0.0001). AgNPs-coated gloves reduced microbial adhesion of mixed-species biofilms. A series of contamination and transmission assays demonstrated no transmission of viable organisms. Biocompatibility analysis confirmed high viability of HaCaT and L929 cells at all concentrations of AgNPs tested. The coated gloves were non-toxic with direct contact with L929 cells. The highly efficacious AgNPs-coated gloves potentially provide additional protection against transmission of healthcare-associated infections.


Assuntos
Anti-Infecciosos , Infecção Hospitalar , Eucalyptus , Nanopartículas Metálicas , Antibacterianos/farmacologia , Biofilmes , Humanos , Testes de Sensibilidade Microbiana , Extratos Vegetais/farmacologia , Prata/farmacologia
13.
Mol Genet Genomics ; 296(5): 1071-1083, 2021 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-34159440

RESUMO

Branching in long-lived plants can cause scarring at the base and affect wood density, which greatly inhibits wood yield and quality. Eucalyptus urophylla is one of the most important commercial forest tree species in South China, with diverse branch number and branch angles under different genetic backgrounds. However, the main elements and regulatory mechanisms associated with different branching traits in E. urophylla remain unclear. To identify the factors that may influence branching, the transcriptome and metabolome were performed on the shoot apex (SA), lateral shoot apex (LSA), and stem segment at the 5th axillary bud from the shoot apex (S1) in lines ZQUC14 (A) and LDUD26 (B), with A exhibiting a smaller Ba than B. A total of 307.3 million high-quality clean reads and nine hormones were identified from six libraries. Several differentially expressed regulatory factors were identified between the two genotypes of E. urophylla. The Kyoto Encyclopedia of Genes and Genomes pathways were enriched in plant hormone signal transduction, plant hormone biosynthesis and their transport pathways. Furthermore, gene expression pattern analysis identified genes that were significantly downregulated or upregulated in S1 relative to the SA and LSA segments, and the plant hormone signal transduction pathway was constructed to explain branching development. This study clarified the main plant hormones and genes underlying branch numbers and angles of E. urophylla, confirmed that ABA and SA could promote a larger branch angle and smaller branch number, while IAA has an opposite function. Numbers of key candidate genes involved in plant hormone signal transduction were found in the positive regulation of branch formation. These novel findings should aid molecular breeding of branching in Eucalyptus.


Assuntos
Eucalyptus/crescimento & desenvolvimento , Eucalyptus/genética , Eucalyptus/metabolismo , Reguladores de Crescimento de Plantas/metabolismo , Cromatografia Líquida de Alta Pressão , Perfilação da Expressão Gênica , Regulação da Expressão Gênica de Plantas , Genótipo , Reguladores de Crescimento de Plantas/genética , Brotos de Planta/genética , Brotos de Planta/crescimento & desenvolvimento , Caules de Planta/genética , Caules de Planta/metabolismo , Transdução de Sinais/genética , Espectrometria de Massas em Tandem
14.
Rev Soc Bras Med Trop ; 54: e01472021, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-34105628

RESUMO

INTRODUCTION: The occurrence of Microtriatoma borbai in the state of Espírito Santo, Brazil is reported by the first time. METHODS: A triatomine specimen collected in a hybrid eucalyptus crop in the municipality of Aracruz, Espírito Santo state was found to be a male M. borbai. RESULTS: This finding expands the geographical distribution of M. borbai from four to five Brazilian states. It is the first report of M. borbai occurrence inside a eucalyptus crop. CONCLUSIONS: The occurrence of M. borbai in the state of Espírito Santo broadens the geographical distribution of this species in southeastern Brazil.


Assuntos
Eucalyptus , Reduviidae , Triatominae , Animais , Brasil , Meio Ambiente , Masculino
15.
Molecules ; 26(11)2021 May 28.
Artigo em Inglês | MEDLINE | ID: mdl-34071495

RESUMO

Increasing applications and markets for essential oils could bring new opportunities for cost-effective and sustainable management of unused forestry biomass; however, better knowledge of the production and application of such essential oils is necessary. The objective of this work is to contribute to greater knowledge of the essential oil production on a pilot scale from foliage biomass of wild shrubs and tree residues produced in some forestry enhancement operations and to study their antioxidant capacity (ORAC-oxygen radical absorbance capacity). Fresh biomass (twigs) of seven species (E. globulus, E. nitens, P. pinaster, P. sylvestris, R. officinalis, C. ladanifer, and J. communis) was manually collected in Spain in two different periods and was ground at 30 mm and distilled in a 30 L stainless steel still with saturated steam. The essential oil components were identified by GC-MS and quantified by GC-FID, and their antioxidant activity was determined with the ORAC method. Promising results on essential oil yield were obtained with E. globulus, E. nitens, R. officinalis, and J. communis. All essential oils studied exhibited antioxidant capacity by the ORAC assay, particularly that from C. ladanifer. Moreover, oxygenated sesquiterpenes contents, one of the minor components of oils, were significantly correlated with ORAC values.


Assuntos
Antioxidantes/química , Óleos Voláteis/química , Folhas de Planta/metabolismo , Biomassa , Cromatografia Gasosa , Cistus , Eucalyptus/química , Florestas , Cromatografia Gasosa-Espectrometria de Massas , Geografia , Monoterpenos/análise , Óleos Vegetais/química , Sesquiterpenos/análise , Espanha , Árvores
16.
Oecologia ; 196(3): 795-803, 2021 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-34142232

RESUMO

The diets of individual animals within populations can differ, but few studies determine whether this is due to fundamental differences in preferences or capacities to eat specific foods, or to external influences such as dominance hierarchies or spatial variation in food availability. The distinction is important because different drivers of dietary specialisation are likely to have different impacts on the way in which animal populations respond to, for example, habitat modification. We used a captive feeding study to investigate the mechanisms driving individual dietary specialisation in a population of wild koalas (Phascolarctos cinereus) in which individuals predominantly ate either Eucalyptus viminalis or Eucalyptus obliqua foliage. All six koalas that primarily ate E. viminalis in the wild avoided eating E. obliqua for more than 1 month in captivity. In contrast, all seven koalas that primarily ate E. obliqua could be maintained exclusively on this species in captivity, although they ate less from individual trees with higher foliar concentrations of unsubstituted B-ring flavanones (UBFs). Our results show that fundamental differences between individual animals allow some to exploit food resources that are less suitable for others. This could reduce competition for food, increase habitat carrying capacity, and is also likely to buffer the population against extinction in the face of habitat modification. The occurrence of fundamental individual specialisation within animal populations could also affect the perceived conservation value of different habitats, translocation or reintroduction success, and population dynamics. It should therefore be further investigated in other mammalian herbivore species.


Assuntos
Eucalyptus , Phascolarctidae , Animais , Dieta , Ecossistema , Árvores
17.
Ecotoxicol Environ Saf ; 221: 112426, 2021 Sep 15.
Artigo em Inglês | MEDLINE | ID: mdl-34166940

RESUMO

Lead (Pb) and cadmium (Cd) are considered as a typical heavy metals in aqueous solution, which may pose adverse health effects on human beings. For the removal of these two pollutants, magnesium oxide (MgO) was successfully immobilized onto eucalyptus biochar (BC) matrix via simple and cost-effective pyrolysis process of MgCl2-pretreated eucalyptus biomass under high temperature (500 °C). Synthesized MgO nanoparticles-biochar composites (MBC) exhibited superior removal performance for target pollutants, and achieve 99.9% removal efficiency for Pb(II) and Cd(II) at optimum conditions (0.02 g, pH in range of 4-7, and reaction time 120, 240 min). Furthermore, the maximum theoretical adsorbing amount of MBC was 829.11 mg/g for Pb(II) and 515.17 mg/g for Cd(II). Pseudo-second-order model and Langmuir models were well-determined for isotherm and adsorption kinetics. FTIR, XRD, and XPS analysis revealed that precipitation and ion exchange was of great importance for the removal of contaminants. Besides, cation-π interaction and complexation from the carbon-containing functional groups should not be neglected. Considering the advantage of low-cost, facile preparation, and brilliant adsorption capacity, it is anticipated that MBC has a promising prospect for the broad application in Pb(II)/Cd(II)-containing wastewater treatment.


Assuntos
Cádmio/química , Carvão Vegetal/química , Eucalyptus , Chumbo/química , Óxido de Magnésio/química , Poluentes Químicos da Água/química , Purificação da Água/métodos , Adsorção , Soluções
18.
Nat Ecol Evol ; 5(7): 1003-1010, 2021 07.
Artigo em Inglês | MEDLINE | ID: mdl-33972737

RESUMO

The 2019-20 wildfires in eastern Australia presented a globally important opportunity to evaluate the respective roles of climatic drivers and natural and anthropogenic disturbances in causing high-severity fires. Here, we show the overwhelming dominance of fire weather in causing complete scorch or consumption of forest canopies in natural and plantation forests in three regions across the geographic range of these fires. Sampling 32% (2.35 Mha) of the area burnt we found that >44% of the native forests suffered severe canopy damage. Past logging and wildfire disturbance in natural forests had a very low effect on severe canopy damage, reflecting the limited extent logged in the last 25 years (4.5% in eastern Victoria, 5.3% in southern New South Wales (NSW) and 7.8% in northern NSW). The most important variables determining severe canopy damage were broad spatial factors (mostly topographic) followed by fire weather. Timber plantations affected by fire were concentrated in NSW and 26% were burnt by the fires and >70% of the NSW plantations suffered severe canopy damage showing that this intensive means of wood production is extremely vulnerable to wildfire. The massive geographic scale and severity of these Australian fires is best explained by extrinsic factors: an historically anomalous drought coupled with strong, hot dry westerly winds that caused uninterrupted, and often dangerous, fire weather over the entire fire season.


Assuntos
Eucalyptus , Incêndios Florestais , Florestas , New South Wales , Vitória
19.
Carbohydr Polym ; 265: 118037, 2021 Aug 01.
Artigo em Inglês | MEDLINE | ID: mdl-33966824

RESUMO

Electron beam irradiation (EBI) is an alternative treatment for intrinsic viscosity (IV) control in cellulose pulps, but has never been integrated in full bleaching sequences for comparison to conventional methods. Both eucalyptus kraft (EK) paper pulp and beech sulfite (BS) dissolving pulp were subjected to totally chlorine free (TCF) bleaching sequences comprising either EBI, ozone, or both for IV control. Additionally, effects of EBI on hexenuronic acid (HexA) and xylan were investigated. IV was adjusted to 450-500 mL g-1 and properties including carbonyl content, kappa, brightness, alkali-resistance and sugar composition were compared. Pulps produced with EBI had a higher alkali-resistance, uniformity and less cellulose oxidation. However, the degree of bleaching (DoB) was low without the use of ozone. HexA content in a birch pulp was halved by EBI. Isolated xylans were more resistant to irradiation than cellulose with little decrease of molar masses and moderate oxidation.


Assuntos
Celulose/química , Eucalyptus/química , Fagus/química , Ozônio/química , Álcalis/química , Clareadores/química , Elétrons , Ácidos Hexurônicos/química , Lignina/química , Oxirredução , Papel , Radiação , Viscosidade , Xilanos/química
20.
Ecol Appl ; 31(6): e02383, 2021 09.
Artigo em Inglês | MEDLINE | ID: mdl-34042236

RESUMO

Infrequent, high-intensity disturbances can have profound impacts on forested landscapes, changing forest structure and altering relative species abundance. However, due to their rarity and the logistical challenges of directly observing such extreme events, both the spatial variability of disturbance intensity and the species-specific responses to this variability are poorly understood. We used observed patterns of mortality across a fire severity gradient following the 2009 Black Saturday fires in southeastern Australia to simultaneously estimate (1) species- and size-specific susceptibility to fire-induced mortality and (2) fire intensity. We found broad variation in patterns of fire susceptibility among the 10 tree species (five eucalypts and five non-eucalypts) sufficiently abundant for analysis. Among the eucalypts, Eucalyptus obliqua was the most resistant to fire-induced mortality, with trees of ~25 cm DBH having a 50% probability of surviving even the most intense fires. In contrast, E. regnans had 100% mortality across all size classes when subjected to high-intensity fire. Basal resprouting occurred in six of the study species and, when accounted for, fundamentally changed the mortality profile of these species, highlighting the importance of resprouting as an adaptation to fire in these landscapes. In particular, the two iconic cool temperate rainforest species (Nothofagus cunninghami and Atherosperma moschatum) were strong resprouters (~45% of individuals were able to resprout after being top-killed by fire). We also found evidence for compositional shifts in regeneration above threshold values of fire intensity in cool temperate rainforest and mixed forest sites, both of which have important conservation values within these landscapes. The observed patterns of species- and size-specific susceptibility to fire-induced mortality may be used to anticipate changes in forest structure and composition in the future. In addition, they may also help guide forest management strategies that reduce the length of time individual trees are exposed to potentially lethal fires, thereby increasing the resilience of these forests to future fires.


Assuntos
Eucalyptus , Incêndios , Austrália , Florestas , Humanos , Especificidade da Espécie
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