Eucalypts

Scholars studying the globalization of Australian trees have previously emphasized the rapid natural propagation of Australian trees outside of their native habitats, believing their success to be a reversal of ‘‘ecological imperialism’’ from the ‘‘new world’’ to the ‘‘old world.’’ This article argues that the expansion of Australian trees should not be viewed as a biological phenomenon, but as the result of a long-term attempt by powerful states and state-sponsored scientists to select and breed Australian species that could grow in a variety of climates and ecological conditions. Five non- biological factors largely determined the success of these attempts to grow Australian trees: the abundance or paucity of natural forests, state power, the amount of scientific research directed to planting Australian trees, the cost of labor, and the ability to utilize hardwood timbers and bark. This paper compares the use of Australian trees in Australia, India, and South Africa to demonstrate that biology was not the determining factor in the long-term success of many Australian genera and species.

Machine learning and spectral index (SI) thresholding approaches have been tested for fire-severity mapping from local to regional scales in a range of forest types worldwide. While index thresholding can be easily implemented, its operational utility over large areas is limited as the optimum index may vary with forest type and fire regimes. In contrast, machine learning algorithms allow for multivariate fire classifications. This study compared the accuracy of fire-severity classifications from SI thresholding with those from Random Forests (RF). Reference data were from 3730 plots within the boundaries of eight major wildfires across the six temperate forest 'functional' groups of Victoria, southeastern Australia. The reference plots were randomly divided into training and validation datasets (60/40) for each fire-severity class (unburnt, low, moderate, high) and forest functional group. SI fire-severity classifications were conducted using thresholds derived in a previous study based on the same datasets. A RF classification algorithm was trained to derive fire-severity levels based on appropriate spectral indices and their temporal difference. The RF classification outperformed the SI thresholding approach in most cases, increasing overall accuracy by 11% on a forest-group basis, and 16% on an individual wildfire basis. Adding more predictor variables into the RF algorithm did not improve classification accuracy. Greater overall accuracies (by 12% on average) were achieved when in situ data (rather than data from other fires) were used to train the RF algorithm. Our study shows the utility of Random Forest algorithms for streamlining fire-severity mapping across heterogeneous forested landscapes.

In the late summer of 2009, a massive firestorm swept through more than one million acres of dense bush in the southeast corner of Australia, killing 173 people and leaving more than 7,000 homeless. In the aftermath of the disaster, commentators almost universally described the blaze as "unprecedented." This essay examines that claim in the light of contex-tualizing environmental histories and finds that although such firestorms are rare, they are far from unprecedented; they are in fact a necessary part of the cycle of regeneration in certain types of eucalypt forest. The idea that a never-before-witnessed event is unprecedented calls into question the shallow temporal frames through which deep time environmental phenomena are understood in Australian settler culture and offers an insight into often unno-ticed ways in which contemporary society struggles with the colonial legacy. This struggle sits next to the ambition of land management authorities to adopt traditional Indigenous mosaic-patterned cool-burning techniques as part of a fire mitigation strategy, without directly addressing the colonial history inscribed on the land they are commissioned to manage.

A family-wide palynological study of Myrtaceae was conducted using scanning electron microscopy (SEM) and light microscopy (LM). In this part of the study, the pollen morphology of 18 genera and 150 species from the Myrtaceae tribes of subfamily Myrtoideae, Eucalypteae, Lophostemoneae, Syncarpieae, Xanthostemoneae and subfamily Psiloxyloideae are presented. It was found that the most commonly observed pollen in these groups was parasyncolpate with a rugulate exine, whereas some species possessed an apocolpial island. The large, and sometimes syndemicolpate, pollen of Eucalypteae genera Angophora and Corymbia differed from all other genera. Most Eucalyptus pollen had endopores with a thickened exine.

Abstract We studied egg production and the occurrence of adaptive superparasitism in Anaphes nitens, an egg parasitoid of the Eucalyptus snout beetle Gonipterus scutellatus. First, we determined whether A. nitens females were synovigenic or pro-ovigenic. Newly emerged females were allowed to lay eggs alone during 3 days on six fresh egg capsules. A first group of females (n= 25) were killed by freezing and the remaining females (n= 21) were maintained during two extra days with food, but without hosts.

Machine learning and spectral index (SI) thresholding approaches have been tested for fire-severity mapping from local to regional scales in a range of forest types worldwide. While index thresholding can be easily implemented, its operational utility over large areas is limited as the optimum index may vary with forest type and fire regimes. In contrast, machine learning algorithms allow for multivariate fire classifications. This study compared the accuracy of fire-severity classifications from SI thresholding with those from Random Forests (RF). Reference data were from 3730 plots within the boundaries of eight major wildfires across the six temperate forest 'functional' groups of Victoria, southeastern Australia. The reference plots were randomly divided into training and validation datasets (60/40) for each fire-severity class (unburnt, low, moderate, high) and forest functional group. SI fire-severity classifications were conducted using thresholds derived in a previous study based on the same datasets. A RF classification algorithm was trained to derive fire-severity levels based on appropriate spectral indices and their temporal difference. The RF classification outperformed the SI thresholding approach in most cases, increasing overall accuracy by 11% on a forest-group basis, and 16% on an individual wildfire basis. Adding more predictor variables into the RF algorithm did not improve classification accuracy. Greater overall accuracies (by 12% on average) were achieved when in situ data (rather than data from other fires) were used to train the RF algorithm. Our study shows the utility of Random Forest algorithms for streamlining fire-severity mapping across heterogeneous forested landscapes.

RESUMEN La degradación superficial en madera de exteriores se debe a una combinación de factores meteorológicos inherentes al entorno de exposición y a la colonización de organismos xilófagos. Desde un punto de vista técnico y económico se trata de uno de los principales problemas para la industria de productos y materiales hechos a partir de la madera. El objetivo del presente trabajo es el de monitorizar la degradación superficial de las maderas de Corymbia citriodora y Eucalyptus tereticornis originarias de plantaciones de rápido crecimiento de Brasil, las cuales han sido expuestas a ensayos de intemperismo natural en tres entornos ambientales distintos. La monitorización de los cambios en el material fue realizada mediante estimaciones del color (método CIEL*a*b*), en ciclos de 45 días, hasta completar un periodo de 360 días de exposición. Los resultados mostraron que el material expuesto al entorno forestal fue menos afectado por los factores ambientales, lo que ha sido probablemente debido al aislamiento térmico y solar que proporciona este tipo de ecosistema. A su vez, se observó que las probetas de madera de Corymbia citriodora presentaron mayor resistencia al deterioro que las probetas de madera de Eucalyptus tereticornis, posiblemente debido a ciertas diferencias en su constitución química. ABSTRACT Surface degradation in outdoor wood and products is due to a combination of inherent climate factors together with colonization of decay organisms. From a technical and economic standpoint it is one of the main problems for the industry of products and materials made from wood. The aim of this work is to track the surface degradation of Corymbia citriodora and Eucalyptus tereticornis timbers originating from fast-growing plantations in Brazil, which have been exposed to outdoor weathering tests in three different environmental conditions. Changes in the material were monitoring using color measurement (CIEL*a*b* method), in cycles of 45 days up to a period of 360 days of exposure. The results showed that timber exposed to a forest ecosystem was less affected by environmental factors; this is probably due to climate insulation provided by these ecosystems. Besides, it was observed that samples of Corymbia citriodora had higher resistance to degradation compared with samples of Eucalyptus tereticornis, possibly due to differences in its chemical constitution.

In this study approximately 420 of the described species of Eucalyptus were examined for cyanogenesis. Our work has identified an additional 18 cyanogenic species, 12 from living tissues and a further six from herbarium samples. This brings the total of known cyanogenic species to 23, representing approximately 4% of the genus. The taxonomic distribution of the species within the genus is restricted to the subgenus Symphyomyrtus, with only two exceptions. Within Symphyomyrtus, the species are in three closely related sections. The cyanogenic glycoside was found to be predominantly prunasin (1) in the 11 species where this was examined. We conclude that cyanogenesis is plesiomorphic in Symphyomyrtus (i.e. a common basal trait) but has probably arisen independently in the other two subgenera, consistent with recent phylogenetic treatments of the genus. The results of this study have important implications for the selection of trees for plantations to support wildlife, and to preserve genetic diversity.

Fire is a natural part of most Australian landscapes and has an important influence on the biological productivity and biotic composition of many ecosystems. Although fire is commonly used as a management tool, the precise nature of the way it may influence productivity and biotic composition is often poorly understood and, as a consequence, its use is controversial. This paper considers the use of fire for the management of ecosystems. Specifically, the influences of fire on environmental heterogeneity and the effects these have on shaping biological productivity and biotic patterns are discussed. Heterogeneity that affects biotic response includes variation in biophysical attributes of landscapes such as topography, fire regimes and the spatial attributes of fire. Examples are used to address the interplay between fires, environmental heterogeneity and biological pattems: (1) the effects of fires on plant resource availability; (2) crown scorch in eucalypt forests; and (3) the effects of spatial variation (patchiness) within a fire on species composition. Heterogeneity should be considered explicitly in management because prescriptions devised elsewhere may not be able to be imported with confidence to all sites and the responses of the biota to fires may differ from available information. Ecological monitoring and research into the ecological effects of heterogeneity are required to provide a predictive understanding of natural systems and provide information to aid decisions about the use of fire as a management tool.

Cinco espécies de Eucalyptus (E. grandis, E. urophylla, E. Camaldulensis, E. torelliana e E. phaeotrica), dentre as dez espécies mais utilizadas em plantações florestais de larga escala, foram submetidas ao aumento do CO2 e à interação deste com estresse hídrico para avaliar seu comportamento estomático. As três primeiras espécies pertencem ao subgênero Symphyomyrtus, a quarta espécie é do subgênero Corymbia e o E. Phaeotrica pertence ao subgênero Monocalyptus. Mudas destas espécies com idade de 2,5 meses foram cultivadas em quatro pares de câmaras de topo aberto, com duas plantas de cada espécie por câmara e quatro repetições em duas concentrações de CO2: 350 ± 30 mmol mol-1 e 700 ± 30 mmol mol-1. Após 100 dias de crescimento nas câmaras, medições de trocas gasosas foram realizadas, após o que metade das plantas em cada câmara foi submetida ao estresse hídrico pela supressão da irrigação, permanecendo as demais plantas sob irrigação diária. O estresse hídrico reduziu a condutância estomática, a fotossíntese e as taxas de transpiração em todas as espécies. O efeito do estresse hídrico no fechamento dos estômatos foi similar em ambas as concentrações de CO2, embora os efeitos positivos do aumento do CO2 sobre a fotossíntese e a eficiência do uso da água se mantivessem por um período comparativamente mais longo. A taxa fotossintética do E. Phaeotrica permaneceu alta mesmo após o quarto dia do estresse hídrico. O estresse hídrico aumentou a fotoinibição da fotossíntese, medida por fluorescência da clorofila, que variou entre as espécies, assim como em relação à concentração de CO2. Os resultados mostram diferenças na resposta estomática entre espécies dos subgêneros Symphyomyrtus e Monocalyptus.

Cinco espécies de Eucalyptus (E. grandis, E. urophylla, E. Camaldulensis, E. torelliana e E. phaeotrica), dentre as dez espécies mais utilizadas em plantações florestais de larga escala, foram submetidas ao aumento do CO2 e à interação deste com estresse hídrico para avaliar seu comportamento estomático. As três primeiras espécies pertencem ao subgênero Symphyomyrtus, a quarta espécie é do subgênero Corymbia e o E. Phaeotrica pertence ao subgênero Monocalyptus. Mudas destas espécies com idade de 2,5 meses foram cultivadas em quatro pares de câmaras de topo aberto, com duas plantas de cada espécie por câmara e quatro repetições em duas concentrações de CO2: 350 ± 30 mmol mol-1 e 700 ± 30 mmol mol-1. Após 100 dias de crescimento nas câmaras, medições de trocas gasosas foram realizadas, após o que metade das plantas em cada câmara foi submetida ao estresse hídrico pela supressão da irrigação, permanecendo as demais plantas sob irrigação diária. O estresse hídrico reduziu a condutância ...

Distributions of common species of Eucalyptus in south-eastem Australia are related to gradients in temperature and rainfall. To determine whether intrinsic water-use efficiency (as indexed by carbon isotope discrimination, A) or other leaf attributes were related to climate of native habitats, we sampled 17 populations representing 14 species of Eucalyptus growing in a common garden in southcentral New South Wales. Phreatophytes were clearly distinguished from populations that are totally dependent upon soil moisture derived from rainfall by having higher A at a particular level of rainfall. Among 12 non-phreatophytic populations (11 species), A was positively correlated with mean annual precipitation (r = 0.75, P = 0.005), December-March precipitation (r = 0.79, P = 0.002), an index of annual soil moisture (r = 0.81, P = 0.001) and seasonality of precipitation (r = 0.85, P < 0.001). There were similarly strong but negative correlations between A and potential evaporation during the summer months, but A was not correlated with annual potential evaporation of the source sites. Leaf mass per unit area (pe) was negatively correlated with indices of water availability, positively correlated with nitrogen per unit leaf area (r = 0.90, P < 0.001), and negatively correlated with A (r =-0.73, P = 0.007). A was negatively correlated with area-based leaf nitrogen (r =-0.79, P = 0.002). These complementary correlations among A, p,, and nitrogen per unit leaf area indicate that variation in A may stem largely from variation in photosynthetic capacity. The results provide strong evidence that variation in A and p, reflect genetic adaptations to native habitats.

O objetivo deste estudo foi realizar simulação, verificando a rentabilidade de um sistema
agrossilvicultural composto por eucalipto, arroz, soja e gado, de acordo com a variação do
espaçamento de plantio do eucalipto e dos sistemas agroflorestais, bem como comparar os
resultados com o plantio convencional do eucalipto. A análise econômica foi realizada mediante
os métodos de avaliação de projetos florestais, Valor Presente Líquido (VPL), Benefício
Periódico Equivalente (BPE), Razão Benefício/Custo (B/C) e Taxa Interna de Retorno (TIR).
Todos os projetos analisados apresentaram-se viáveis economicamente, sendo que o eucalipto
em monocultivo apresentou melhores resultados. Verificou-se que o ganho em área com plantio
das culturas agrícolas e criação de gado não obtém o mesmo retorno econômico caso a área
estivesse com plantio de árvores.

In this study, we aimed evaluate the behavior of the brown-rot fungus Gloeophylum trabeum and white-rot fungus Pycnoporus sanguineus on thermally-modified Eucalyptus grandis wood. To this end, boards from five-year-eleven-month-old E. grandis trees, taken from the Duratex-SA company stock, were thermally-modified between 180 °C and 220 °C in the Laboratory of Wood Drying and Preservation at Universidade Estadual Paulista-UNESP, Botucatu, Sao Paulo state Brazil. Samples of each treatment were tested according to the ASTM D-2017 (2008) technical norm. The accelerated decay caused by the brown-rot fungus G. trabeum was compared with the decay caused by the white-rot fungus P. sanguineus, studied by Calonego et al. (2010). The results showed that (1) brown-rot fungus caused greater decay than white-rot fungus; and (2) the increase in temperature from 180 to 220 °C caused reductions between 28.2% and 70.0% in the weight loss of E. grandis samples incubated with G. trabeum.

Forest dieback is a worldwide problem that is likely to increase with climate change and increasing human demands for resources.  Eucalyptus camaldulensis forests are an acute example of forest dieback, with 70% of the Victorian Murray River floodplain in some state of dieback.  If we are to halt dieback in these floodplain forests, we need to understand what makes stands susceptible to dieback.  Forest diebacks are often related to stand structure, with dieback more severe in senescent or high-density stands.  We determined whether certain stand structures make these forests more susceptible to dieback.  We undertook an extensive survey of 176 stands across 100 000 ha of forest, covering the range of stand condition on this floodplain.  Large and small trees (20, 40, 80 and 120 cm diameter) showed a similar reduction in the probability of being alive with decreasing stand condition.  A slight improvement in stand condition was found at higher densities and basal areas, which may reflect the higher productivity or younger age of these stands.  Stand condition was moderately, positively correlated with longitude, with stand condition being higher in the east of the Murray River floodplain where flooding frequencies are currently higher.  This suggests that dieback of these floodplain forests would be more effectively mitigated by increased water availability through flooding than by altering stand structure.

Plants have evolved a vast array of defence mechanisms to avoid or minimize damage caused by herbivores and pathogens. The costs and benefits of defences are thought to vary with the availability of resources, herbivore pressure and plant functional traits. We investigated the resource (nitrogen) and growth cost of deploying cyanogenic glycosides in seedlings of Eucalyptus cladocalyx (Myrtaceae). To do this, we grew the plants under a range of soil N conditions, from levels that were limiting for growth to those that were saturating for growth, and we measured correlations between foliar chemical and performance attributes. Within each N treatment, we found evidence that, for every N invested in cyanogenic glycosides, additional N is added to the leaf. For the lowest N treatment, the additional N was less than one per cyanogenic glycoside, rising to some two Ns for the other treatments. The interaction between cyanogenic glycosides and both condensed tannins and total phenolic compounds was also examined, but we did not detect correlations between these compounds under constant leaf N concentrations. Finally, we did not detect a correlation between net assimilation rate, relative growth rate and cyanogenic glycoside concentrations under any soil N treatment. We conclude that the growth cost of cyanogenic glycosides was likely too low to detect and that it was offset to some degree by additional N that was allocated alongside the cyanogenic glycosides.

Forest Red Gum eucalypt provides a versatile wood and is converted into different purposes. However, such wood is somewhat limited in structural ends, which highlights the need to exploit this gap through diffusion of mechanical properties of such timber. Obtained results should assist engineers and architects in decision-making for its best building application. This paper studied two physical and fourteen mechanical properties evaluation of Eucalyptus tereticornis at two different moisture contents, following the prescriptions of Brazilian (ABNT NBR 7190: 1997) and North American (ASTM D-143-14: 2014) standard documents. Thus, 1091 repeats were carried out for all properties. By a moisture reduction from 30% to 12%, the bulk density and eleven strength properties statistically showed changes such as modulus of rupture (static bending, parallel and perpendicular compressions), modulus of elasticity (perpendicular compression and static bending), shear stress, tangential cleavage, a...

Spiral grain in 181 trees from a 9-year-old plantationgrown Eucalyptus dunnii was normally distributed with mean −0.33 degrees (to the left) and standard deviation 1.7 degrees, and was affected by family and by crown asymmetry. Interlocking grain was common, exhibiting a mean amplitude of 3.4 degrees (standard deviation 1.5◦) and a mean wavelength of 39 mm (standard deviation 12 mm). The relatively large amplitude of interlocking grain means that most trees will have spiral grain that alternates between left and right during each year. The wavelength of interlocking grain is influenced by tree size, but amplitude of interlocking is under genetic control. Both spiral grain and the amplitude of any interlocking were heritable (h2 = 0.99 and 0.63 respectively).