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Guthrie, J - Eucalyptus deglupta

Page history last edited by PBworks 16 years, 1 month ago

Jennifer Guthrie – PBIO 209 – Dr. Brown – 03.06.08

Eucalyptus deglupta

(a.k.a. “Rainbow Eucalyptus”)

(Photo courtesy of Google Images)

One sunny summer afternoon on the island of Maui in Hawaii, I had the pleasure of taking a leisurely drive to the small town of Hana. This drive is a spectacular journey through the many native indigenous plants that engulf this particular island and there was one tree that caught my attention. My traveling companions and I stopped along the way to snap a few pictures and noticed a tree with very smooth colorful bark that resembled a rainbow. Being the plant enthusiast that I am I quickly asked: “What type of tree is that?” My traveling buddy promptly answered: “A gum tree.” So I snapped a few pictures and gave the tree a good rub down to really remember what it felt like and we were on our way. This tree really enticed my curiosity and upon making it back to the continental states and my home college of Ohio University to attend classes, I was ready to find out more about this particular tree. Luckily, one of classes the following quarter was entitled American Forests in which we spent much time discussing the native trees of Hawaii, and so I soon learned the real name of this gorgeous tree: the “Rainbow Eucalyptus.”

Eucalyptus deglupta Quick Facts:

** Belongs to the Family: Myrtaceae

** Native Habitat: Indonesia, Papua New Guinea, Philippines

** Common Names: “Rainbow Eucalyptus”; “Mindanao Gum”

** Evergreen tree found in Tropical/Subtropical moist broadleaf forests

** Introduced into Hawaiian Islands in 1929

(Photo courtesy of Google images)

The Rainbow Eucalyptus originates from the Mindanao area of the island of the Philippines and hence that is where it received one of its common names of “Mindanao Gum.” Today, it is best known for its Hawaiian and Southern United States habitat. According to the World Agro Forestry Tree Database, the Rainbow Eucalyptus retains its leaves year round and is an annual growing tree that can reach up to 75m. For optimal development, the Rainbow Eucalyptus requires full overhead light and therefore growth is usually rapid. Its comfortable temperature for growth is in the area of 23-31 degrees Celsius and it can successfully grow in loamy soils as well as coarse, sandy, and volcanic-ash soils. Eucalyptus deglupta, being a tropical plant, enjoys a habitat of lowland moist areas with a high annual rainfall, yet the tree cannot withstand prolonged flooding. The Rainbow can tolerate light frosts when its habitat is in the southern U.S. states but it will not make it through traditional frosts of the northern U.S. states.

The bark of the Eucalyptus deglupta is splashed brightly with many colors including grey, green, pink, orange, red, and brown, and this is where it received its more common name of “Rainbow Eucalyptus.” The bark changes colors on a continuous cycle as it exfoliates and it has a new appearance from month to month. As the color travels down the bark to the roots it changes from a bright rainbow of colors to a more neutral trunk color of browns and faint oranges, and the roots do not have the colorful nature that the bark does. The texture of the bark is quite smooth and soft to the touch which makes this species of Eucalyptus quite interesting to examine.

In addition to being a gorgeous tree, the Rainbow Eucalyptus creates value for its wood. Plantations around the world use its wood for pulp production as well as furniture, veneer, particle board, plywood, etc. The wood is of a moderate strength yet not typically durable, and unlike most Eucalypts the Rainbow does not produce aromatic oils that can be commercialized.

(photo courtesy of Forest and Kim Starr)

Kamarere hardwood: (photo courtesy of: http://www.exotichardwoods-eurasia.com/kamarere.htm)

In Costa Rica, coffee farmers use the shade of this tree to effectively grow their coffee for profit. “…tropical farmers use very fast-growing and presumably competitive trees in tree-crop associations.” “…There was no evidence of a negative effect of the trees on coffee growth, yields and mineral nutrition despite fast tree growth (Schaller pg 205).” “Costa Rican farmers have found that Eucalyptus deglupta is a suitable shade tree for coffee on sites with high precipitation and soil fertility, confirming experiences of coffee farmers in other tropical regions. Under these conditions, tree growth is fast, leading to early economic returns through timber production without evidence of simultaneous increase in competition with the coffee for soil resources. The compatibility of coffee with fast-growing shade trees is due to a combination of high availability of soil resources, their complementary exploitation by tree and crops, especially through a small-scale horizontal and, to a lesser extent, vertical partitioning of the soil between coffee and tree roots, and high competitiveness of the coffee root system itself (Schaller 214).”

Distribution of Eucalyptus deglupta:

Found in grey areas of Australia, Costa Rica, El Salvador, Honduras, Indonesia, Liberia, Mexico, Nicaragua, Niger, Nigeria, Panama, Papua New Guinea, Philippines, San Marino, Trinidad and Tobago, and United States.

Found present in the United States though status is not known: Arizona, California, Florida, Hawaii, Louisiana, Nevada, Oregon, Puerto Rico, and Texas.

***Both images and text courtesy of: http://zipcodezoo.com/Plants/E/Eucalyptus_deglupta.asp

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Eucalyptus deglupta

Any lover of forests would appreciate the beauty that the Eucalyptus deglupta brings forth is its appearance. In fact, the beauty of this particular tree is why most people first take interest in it and consequently learn more about this specific tree specimen. Let’s discuss a few quick facts about the E. deglupta before diving in on particular issues involving the tree and its habitat.

The Eucalyptus deglupta has many common names associated with it including the most popular being, “gum tree”, “rainbow gum tree”, “Mindanao gum tree”, and “deglupta.” The common names depend on where the tree is found and subsequently named due to the region and culture of that particular place. E. deglupta's taxonomy includes its association with the family Myrtaceae and its authority belonging to the Blume category.

According to the World Agro forestry Centre database, the E. Deglupta is a very large evergreen tree that grows up to 60 m. with a maximum growth of up to 75m. It states that this tree can be up to 240 cm in diameter with buttresses 3-4m high with leaves in an opposite pattern from juvenile to adult phases. It is the bark of this tree that brings forth its great beauty and popularity and makes this species a striking, noticeable tree to observe in the forest. The bark is very smooth to the touch and is characterized by many colors including yellow, brown, pink, purple, and eventually after flaking turns a light green, and the colors of the bark constantly change as the tree exfoliates.

E. deglupta is natively found in the Southeast Asian regions of Indonesia, Papua New Guinea, and the Philippines. It predominately grew in the Mindanao area of the Philippines and was introduced there in the early 1900’s making this tree specimen a relative newcomer as a plantation species. In addition to the Southeast Asian regions, the E. deglupta can also be found in equatorial regions in Central and South America as well as central Africa. E. deglupta gained much popularity for its location on most of the Hawaiian Islands and it is there that most people take a real interest in this tree specimen either on vacation or research opportunities. Here in the United States, the E. deglupta has been introduced in the southern states of Florida, Texas, and the southern Gulf regions on plantations.

The World Wildlife Federation (WWF) defines 14 major habitats on the planet and the E. deglupta belongs to the Tropical and Subtropical Moist Broadleaf Forest Eco-region. The WWF states that this specific eco-region centers itself on the equatorial belt between the Tropics of Cancer and Capricorn and is characterized by a low variability in temperature throughout the year with high levels of rainfall annually (greater than 200 cm). The WWF says that this habitat is dominated by semi-evergreen and evergreen deciduous tree species that have high numbers of diversity in species, more than any other of the terrestrial habitat types. The sensitivity to disturbance stated by the WWF explains that this fragile habitat can be sensitive to plowing, overgrazing and burning because of their challenging climatic and soil conditions.

The World Agro Forestry Tree Database describes the natural habitat of E. deglupta as requiring full overhead light for proper development and dense stands can be found along river banks as well as on sites that have been cleared for agricultural purposes. They state that this particular Eucalypt is the only one that has adapted to lowland and lower montane rainforest habitats and does not grow successfully in areas that have a distinct dry season, and because of this it is widely panted in tropical areas.

According to the College of Tropical Agriculture and Human Resources (CTHAR) of the University of Hawaii at Manoa, the E. deglupta was introduced into Hawaii in 1929 and can be found in Keahua, Wahiawa, Foster, Maui, and Waiakea. The wood from the tree can be used in furniture making, construction, cabinet work, and primarily in Hawaii as boat material. The CTHAR lists the E. degulpta as having a weed risk assessment of 2 which they state as (OK). They also state that the purpose of weed risk assessment is to identify high risk species that are likely invasive, and subsequently make decisions that will reduce the impact of ecological and economical threats to that particular area. The E. deglupta is not currently listed by CTHAR as being an invasive species to the Hawaiian and other Pacific islands.

Ramsden, M., McDonald,J., and Wylie, F.R. in Forests pests in the South Pacific region: A review of the major casual agents of tree disorders, focus their research on major insect pests and fungal diseases of the plantation forest in the Asian Pacific regions. Each pest or fungal disease was considered for their potential threat to the plantations dealing with living plant material, timber and timber products. While the impact of these pests are not great, there are many insect pests that affect the E. deglupta including the Jewel Beetle, Shoot-feeding bugs, the Ambrosia beetle, the Sap sucking bug, the Stem boring beetle, and the Branch boring caterpillar. The article states that the E. degulpta is more likely to be prone to attack from the Stem boring beetle and the major pest affecting the tree lies with the Shoot feeding bug. Most of these pests can be controlled by the use of light pesticides on plantation trees yet because they are not of high threat, this is not always needed in trees growing throughout the forests.

The Eucalyptus deglupta is a remarkable tree for its beauty and serves as a strong wood for commercial products. It is characterized by its tropical climate and therefore becomes of use to those who live in such areas.