Eucalypts Overview and Taxonomy
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Questions and Answers

What is one of the main concerns regarding eucalypt species?

  • High seed production rates.
  • Resistance to pests.
  • Excessive water use. (correct)
  • Rapid growth in urban settings.

    • What regenerative strategy is associated with Eucalyptus fraxinoides?

  • Obligate seeder (correct)
  • Lignotuber sprouter
  • Seed bank performer
  • Root sucker

    • Which of the following is NOT one of the specified concerns related to eucalypt species?

  • Suppression of ground vegetation
  • High soil fertility (correct)
  • Poor wildlife value
  • Increased fire hazard

    • Which eucalypt regenerative strategy is common to three of the listed species?

    <p>Lignotuber sprouter</p> Signup and view all the answers

    How many species of eucalypts are classified as invasive in at least one region?

    <p>Six species</p> Signup and view all the answers

    What is the total area of eucalyptus plantations estimated to be in 2008?

    <p>19.6 million ha</p> Signup and view all the answers

    Which genus of trees is more extensively cultivated than eucalypts?

    <p>Pinus (pines)</p> Signup and view all the answers

    Which region had the highest extent of eucalyptus plantations in the 1990s?

    <p>Americas</p> Signup and view all the answers

    What factor is indicated by lower terminal velocity values in seeds?

    <p>Extended seed dispersal distance</p> Signup and view all the answers

    In which year did the total area of eucalyptus plantations increase to more than four times the global total from the 1970s?

    <p>1990s</p> Signup and view all the answers

    Which country is mentioned as having the highest eucalyptus plantation area in the Americas?

    <p>Brazil</p> Signup and view all the answers

    What is the approximate area of eucalyptus plantations in Oceania?

    <p>0.9 million ha</p> Signup and view all the answers

    Which ecological consequence is associated with eucalyptus plantations as mentioned in the content?

    <p>High mortality of seedlings</p> Signup and view all the answers

    What is the primary classification of the genus Eucalyptus?

    <p>Monocalyptus and Symphyomyrtus</p> Signup and view all the answers

    How many species does the subgenus Symphyomyrtus contain?

    <p>360 species</p> Signup and view all the answers

    Which of the following statements about naturalized eucalypts is accurate?

    <p>Naturalized eucalypts belong almost exclusively to two subgenera.</p> Signup and view all the answers

    What is indicated by the term 'monotypic' in relation to subgenera?

    <p>A subgenus with only one species.</p> Signup and view all the answers

    Which authors contributed to the publication on Eucalypts?

    <p>Marcel Rejmanek and David Mark Richardson</p> Signup and view all the answers

    What height range do most eucalypts typically fall under?

    <p>10 to over 50 meters</p> Signup and view all the answers

    What is a characteristic of the subgenus Eucalyptus in the context of Eucalyptus classifications?

    <p>It includes more than 140 species.</p> Signup and view all the answers

    Which of the following subgenera of Eucalyptus is considered monotypic?

    <p>Angophora</p> Signup and view all the answers

    Which subgenus does the species Eucalyptus camaldulensis belong to?

    <p>Eucalyptus</p> Signup and view all the answers

    Which of the following species is classified as an obligate seeder?

    <p>Symphyomyrtus spathulata</p> Signup and view all the answers

    What is a common characteristic of species in the subgenus Symphyomyrtus compared to those in Eucalyptus?

    <p>Shorter terminal velocities</p> Signup and view all the answers

    Which of the following statements is true regarding the species classified as lignotuber sprouters?

    <p>None are classified as invasive in at least one country.</p> Signup and view all the answers

    What can be inferred about the seed dispersal of Symphyomyrtus species?

    <p>They can be dispersed longer distances by wind due to their smaller size.</p> Signup and view all the answers

    Which Eucalyptus species is explicitly mentioned as having no conclusive evidence of naturalization?

    <p>Eucalyptus camaldulensis</p> Signup and view all the answers

    How do the seeds of the subgenus Eucalyptus generally compare to those of Symphyomyrtus?

    <p>They are generally larger.</p> Signup and view all the answers

    Which factor is pointed out as primary in determining invasive species classification?

    <p>Seed dispersal methods</p> Signup and view all the answers

    What characteristic of eucalypts contributes to their potential spread along rivers and streams?

    <p>Seeds can be dispersed by running water</p> Signup and view all the answers

    Which factor is NOT mentioned as a concern regarding the planting of eucalypts near water bodies?

    <p>Nutrient depletion of soil</p> Signup and view all the answers

    What may be a reason for the extensive planting of invasive species like eucalypts?

    <p>Growth and timber characteristics</p> Signup and view all the answers

    What is suggested about the classification of eucalypts in terms of invasiveness?

    <p>They are generally considered noninvasive.</p> Signup and view all the answers

    Which of the following statements about eucalypt seedlings is true?

    <p>They establish spontaneously in suitable habitats.</p> Signup and view all the answers

    What environmental issue arises from planting eucalypts near rivers?

    <p>Potential spread of their seedlings due to flooding</p> Signup and view all the answers

    Regarding the habitats suitable for eucalypt seedling establishment, which statement is accurate?

    <p>Flooded or eroded banks are ideal habitats.</p> Signup and view all the answers

    What is a limitation to the planting of eucalypts near freshwater sources?

    <p>Their seeds can be dispersed far by water.</p> Signup and view all the answers

    What is one potential negative impact of consecutive cutting cycles of eucalypts?

    <p>Long-term yield decline</p> Signup and view all the answers

    Which eucalypt species are noted for their contribution to the honey industry?

    <p>Eucalyptus camaldulensis and Eucalyptus cladocalyx</p> Signup and view all the answers

    What practice is imperative for maintaining site quality and biomass production of eucalypts?

    <p>Prohibiting or controlling litter raking</p> Signup and view all the answers

    How does the species diversity in eucalypt plantations compare to that of native vegetation?

    <p>Lower species diversity in eucalypt plantations</p> Signup and view all the answers

    What is a potential benefit of growing eucalypts on degraded soils?

    <p>Reduction of pressure on native forests</p> Signup and view all the answers

    Which of the following is true about unmanaged stands of eucalypts?

    <p>They accumulate highly flammable dead material</p> Signup and view all the answers

    What factor contributed to the discussions regarding the intensity of the Berkeley–Oakland Hills fire in 1991?

    <p>Specific eucalypt species' characteristics</p> Signup and view all the answers

    Which statement about the environment where eucalypts are often grown is true?

    <p>They are often grown on abandoned agricultural land</p> Signup and view all the answers

    Study Notes

    Eucalypts

    • Over 800 species of eucalypts (Angophora, Corymbia, Eucalyptus) are native to Australia and some Pacific islands
    • Important solid timber and paper pulp forestry trees
    • Second most commonly cultivated exotic trees after pines
    • Over 70 species are naturalized outside their native range
    • Less invasive than many other widely cultivated trees and shrubs

    Taxonomy, Growth Forms, Regenerative Strategies, and Habitats

    • Classified into three genera: Angophora (14 species), Corymbia (113 species), Eucalyptus (over 740 species)
    • Eucalyptus (sensu stricto) is currently divided into 10 subgenera, 6 of which have only one species
    • Primarily tall trees (10–50+m), some are "mallees" (multi-stemmed, generally under 10 m), and some are shrubs
    • Tallest non-coniferous trees in the world
    • Maximum age estimated between 400–600 years

    Eucalyptus Breeding System

    • Mixed mating with preferential outcrossing
    • Reduction in fruit production, seed set, and seedling vigor after self-pollination
    • Pollination primarily by bees, wasps, birds, mammals or wind

    Eucalyptus Adaptations to Fire

    • Lignotubers: woody swellings at the base of the stem, for sprouting after fire
    • Epicormic buds: buds in the outer bark, for sprouting new branches from stems
    • Serotiny: seeds kept in fruits and released after fire

    Seeds and Seedlings

    • Majority produce seeds with no obvious endosperm.
    • Seeds usually are small (1–3mm), with low weight (0.5-3 mg)
    • Seedlings depend on cotyledon photosynthesis and quick root growth in suitable substrate
    • Seeds can be shed in large numbers (up to 4,000 seeds per m²)

    Cultivation

    • Used for farm construction, fencing, firewood since early European settlement
    • First cultivated species ( E.obliqua) was in 1774 at Kew Botanic Gardens
    • Widely cultivated in tropical, subtropical, and temperate countries for timber, plywood, fiberboard, pulp, poles, firewood, charcoal production, essential oils, honey and for shelter
    • Globally, total plantation area is over 19.6 million hectares (larger than Washington State).

    Naturalized Species

    • Naturalized species mostly belong to the two largest subgenera (Eucalyptus, Symphyomyrtus)
    • Extensive planting has resulted in widespread distribution, but they don't have the same impact as some other species as invaders. Their high success rate is lower compared to other extensively planted trees (pines).
    • Reasons for limited invasiveness include relatively limited seed dispersal, high mortality of seedlings, and lack of compatible ectomycorrhizal fungi.

    Invasiveness of Eucalypts

    • Eucalypts are not considered highly invasive
    • Concerns include water consumption, ground vegetation suppression, increase in fire hazard, and lower wildlife value compared to native species.

    Environmental Controversies and Control Methods

    • Concerns about water use, soil erosion, and fire hazard
    • Relatively non-invasive, spreading is limited
    • Control by cutting back regrowth, application of herbicides to stumps
    • Not usually considered amenable to biological control due to their economic value as timber and/or ornamental trees

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    Eucalypts PDF Article - January 2011

    Description

    Explore the fascinating world of eucalypts, which includes over 800 species native to Australia and the Pacific. This quiz covers their taxonomy, growth forms, regenerative strategies, and breeding systems. Discover why eucalypts are essential for timber and paper pulp industries.

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