Eucalyptus Honor

Nature Study

Requirements

1. How many different species of eucalyptus are there in Brazil?

   Answer: There are about 250 species of eucalyptus in Brazil, the country being the world's largest producer of planted eucalyptus timber. Main species: Eucalyptus grandis, E. urophylla, E. saligna, E. globulus, and E. citriodora are widely cultivated. — Brazil has 9.3 million hectares of planted eucalyptus according to IBÁ 2023, the largest cultivated area of eucalyptus in the world. The first seedling arrived in Brazil in 1865, brought by the botanist Edmundo Navarro de Andrade.

2. What is the origin of the name eucalyptus?

   Answer: 'eucalyptus' comes from the Greek 'eu' (well) + 'kalyptos' (covered), referring to the characteristic of the flower bud covered by an operculum (lid). The name was given by Charles Louis L'Héritier in 1788 when he classified the first scientific European species. — L'Héritier de Brutelle was a French botanist who classified numerous exotic plants brought by the scientific expeditions of the 18th century, with Eucalyptus obliqua (1789) being the first officially described species of the genus, from Tasmania.

3. To what family do eucalyptus trees belong?

   Answer: Eucalyptus trees belong to the family Myrtaceae (myrtles), which also includes the jabuticaba tree, guava tree, Surinam cherry tree, rose apple, and clove. A family with about 5,950 species in 132 genera distributed globally. — The family Myrtaceae was described by Antoine Laurent de Jussieu in 1789, being predominant in Australia and tropical South America. Its leaves contain characteristic aromatic essential oils such as the cineole of medicinal eucalyptus.

4. In what parts of the world can eucalyptus trees be found?

   Answer: Eucalyptus trees are found in Australia (origin), Tasmania, Indonesia, the Philippines, Papua New Guinea, and are cultivated in Brazil, Portugal, Spain, California, South Africa, Ethiopia, China, and India. Species adapted to the local climate grew mainly in tropical and temperate regions of the Southern Hemisphere. — The genus Eucalyptus has more than 700 species, with 95% native to Australia. Global spread occurred during the 19th century, driven by interest in timber, pulp, and essential oil. Brazil is the world's largest producer of eucalyptus pulp (Suzano, Klabin). Portugal uses it for pulp and timber. The USA cultivates it in California. China and India use it for reforestation. Its rapid adaptation and fast growth justify its popularity.

5. In which of the countries listed in the previous requirement are they considered native plants?

   Answer: Eucalyptus is native to Australia, Tasmania, Indonesia (the eastern part), Papua New Guinea, and the Philippines. About 95% of the more than 700 species of the genus Eucalyptus originate from Australia. Other countries cultivate eucalyptus, but as an introduced, non-native species. — Australian evolutionary origin about 50 million years ago. Indonesia and Papua New Guinea have some native species due to their proximity. Brazil, Portugal, California, and South Africa cultivate only introduced species. The distinction between native and exotic is ecologically important: exotics can be invasive. In Brazil, eucalyptus is exotic and requires careful management so as not to impact local biodiversity.

6. Answer the following:
   • Which country has the tallest angiosperms?
   • Where do they grow?
   • What height do they reach?

   Answer: 1) Australia has the tallest angiosperms (flowering plants) in the world, represented by Eucalyptus regnans, known as the 'mountain ash'. 2) They grow in southeastern Australia, in the states of Tasmania and Victoria. 3) Specimens reach over 90 to 100 meters in height, making it the tallest flowering tree on the planet. — Eucalyptus regnans is the tallest angiosperm in the world; only the conifer redwoods (Sequoia sempervirens) surpass it among all trees. The largest living specimens exceed 90 m, and there are historical records of felled trees over 100 m. They grow in the humid, cold forests of Tasmania and Victoria, in Australia.

7. How are eucalyptus trees adapted to:
   • Frequent forest fires?
   • Arid regions?

   Answer: 1) Adaptation to fire: thick bark that protects the trunk; lignotuber (an underground structure with buds that resprout after a fire); many species have seeds that are released or germinate only with the heat of fires. 2) Adaptation to drought: narrow leaves coated with wax reduce water loss through evaporation; many leaves hang down (edge-on to the sun) to reduce exposure; deep roots that capture water in distant soil layers; production of aromatic oils that help reduce herbivory. — Eucalyptus trees co-evolved with fire in Australia. Thick bark in some species (E. obliqua) protects the cambium. The lignotuber allows resprouting after a fire. Seeds in capsules open with heat (serotiny). Hanging leaves reduce sun exposure. Stomata in pits. An extensive root system seeks water. The essential oil is allelopathic: it hinders the growth of other nearby plants. Impressive survival strategies in hostile climates.

8. Answer the following, regarding oil extraction:
   • From which species are eucalyptus oils extracted?
   • Is there oil extraction in your country? Which species is used? Where is this process carried out in your country?
   • What purposes do eucalyptus oils serve?

   Answer: 1) Eucalyptus essential oils are extracted mainly from species rich in eucalyptol, such as Eucalyptus globulus (the most used for medicinal oil), Eucalyptus citriodora (rich in citronellal, used in perfumery and repellents), and Eucalyptus radiata. 2) Yes, there is oil extraction in Brazil, with Eucalyptus citriodora (lemon-scented eucalyptus) being one of the most used species, alongside E. globulus; the process is carried out in distilleries and essential oil industries linked to eucalyptus plantations, especially in the Southeast and South regions (Minas Gerais, São Paulo). Extraction is done by steam distillation: fresh leaves are placed in a still, water vapor passes through them carrying off the volatile oil, and this mixture is cooled in a condenser, separating by density into floral water and essential oil. 3) Eucalyptus oil has several purposes: medicinal use (decongestant, expectorant, and antiseptic, due to eucalyptol), the manufacture of cleaning and hygiene products, insect repellent, scenting and perfumery, as well as use in ointments and inhalants. — Hydrodistillation process: leaves in a pot with water, the vapor rises, condenses, and the oil separates. Yield: 1-3% of the fresh weight of the leaves. Most used species: E. globulus (high cineole), E. citriodora (citronellal). Equipment: copper or stainless steel still, condenser, separator. The oil is stored in a dark bottle, away from heat. Home extraction is possible, but industrial production uses a giant retort for large volumes.

9. What uses does eucalyptus have for humans? Beyond its use, what other benefits can it bring to humans and the environment?

   Answer: For humans: timber, pulp, essential oil, honey, firewood, charcoal, shade, ornamentation. For the environment: carbon sequestration (combating the greenhouse effect), recovery of degraded areas, erosion control, shelter for wildlife in well-managed plantations, oxygen production, and the formation of windbreaks. — A eucalyptus plantation sequesters about 10 t CO2/ha/year. Recovery of eroded areas with deep roots. Correct management includes belts of native forest for biodiversity. Criticisms: extensive monocultures reduce local biodiversity and consume a lot of water. Good practice: rotation with pasture, mosaics with native species. Adventism: responsible environmental stewardship (Gen 1:28).

10. Do one of the following:
    • Collect, press and identify branches of 15 different species of eucalyptus. Note any characteristics important for identification and be able to identify other individuals of the collected species.
    • Draw or photograph 15 different species of eucalyptus, showing the branches and other characteristics important for identification, and be able to identify other individuals of the depicted species.

    Answer: Plant a eucalyptus seedling in a suitable location (with environmental management); or identify 5 different species by their leaves, fruits, and bark; or visit a eucalyptus farm to observe industrial management; or produce homemade essential oil by steam distillation using fresh leaves and a simple still. — The practical options reinforce the theoretical learning. Planting: respect local environmental legislation. Identification: common species in Brazil are E. grandis, E. urophylla, E. citriodora, E. globulus, E. saligna. Farm visit: observe planting, management, harvesting, processing. Home distillation: still, leaves, vapor, condensation. Each activity should be recorded in a notebook with photos for presentation to the instructor.