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Is Eucalyptus a native species?
Eucalyptus is native to Australia and the neighboring islands of Timor and Indonesia. Though there are more than 700 species of Eucalyptus in the world, there are no wild relatives of Eucalyptus that occur naturally in the U.S. Some varieties of Eucalyptus have been introduced in the warmest regions of the U.S., most notably in California, Florida and Texas; and some of these have naturalized.
Is Eucalyptus an invasive species?
Eucalyptus species have been grown for more than 50 years in Brazil on millions of acres in almost ideal growing conditions and have not demonstrated any invasive characteristics. In addition, Eucalyptus species, including E. grandis, have been grown in Florida for decades and are not considered invasive by the Florida Department of Agriculture, which has a very aggressive non-invasive species policy. Eucalyptus has been planted in the extreme southern United States where mild winters will allow some species to grow. There is no evidence that any of these Eucalyptus species have escaped from cultivation and caused any problems in the southeastern United States.
Are varieties of Eucalyptus listed as invasive in certain locations?
Yes, there are some Eucalyptus species listed as invasive by various groups but importantly, none are listed on any state or federal invasive lists. Eucalyptus globulus is reported as being invasive in California; however, ArborGen is not using this species of Eucalyptus or any that closely resemble E. globulus. Eucalyptus grandis x, E. urophylla, E. benthamii and E. macarthurii — which are the species ArborGen grows — have grown for generations without demonstrating any invasive characteristics in Brazil and South Florida.
In California, a species of Eucalyptus was given to land owners as an erosion control plant by the California Extension Service earlier in the 20th century. These trees were planted in draws and water flow areas to help hold the soil. That they have not taken over the entire landscape of California should be considered as proof that the species is not only manageable, but imminently containable. All species of plants, given enough time and the right environment can become naturalized, which does not mean it is invasive. The California Eucalyptus scenario is a very good example.
The State of Hawaii has about 12,000 acres of timber resources in the Waiakea Timber Management Area (WTMA) containing more than 10 different major tree species, roughly 33 percent of which consists of five Eucalyptus species with Eucalyptus saligna and E. grandis present in greatest abundance. Roughly 5,300 acres of the Hamakua Coast timber land is planted in more than six Eucalyptus species with Eucalyptus robusta the largest single component, occupying more than 2,500 acres.
Eucalyptus grandis has been grown in Florida for several decades with no history of invasiveness. Despite this, a recent analysis by the Invasive Plants Working Group at the University of Florida recently concluded that it is “predicted to be invasive.” Such conclusions are often based on examples from other countries (e.g., Africa and India – both countries where Eucalyptus is grown as an important commercial crop). The actual experience of growing Eucalyptus in Florida for more than 20 years contrasts with the experiences in some other countries, and strongly suggests that commercial planting of E. grandis in Florida can be successfully managed with no significant problems.
Can Eucalyptus seeds travel?
Eucalyptus seed is lightweight and very small, not at all well-adapted for wind dispersal. Consequently the distances of seed spread are very limited, generally being confined to about twice the height of the tree (approximately 50 feet for a 25 foot tall tree at harvest age).
Given that bees like Eucalyptus flowers, can the bees spread pollen from Eucalyptus to other trees and plants?
Many Eucalyptus species are adapted for insect pollination, with bees being the predominant pollinator. The potential for bees to spread pollen from Eucalyptus is limited to a relatively short distance, however. Under ideal conditions of humidity and temperature, viable Eucalyptus pollen can only be found within approximately 300 feet (100 meters) from the edge of the nearest tree stand. Studies have verified that bees (Apis spp.) are the most effective pollinators of Eucalyptus, with activity increasing up to 300 feet from the beehive, and decreasing after this distance. Also, it is important to note that ArborGen’s Freeze Tolerant Eucalyptus contain a pollen control gene, inhibiting the Eucalyptus to produce pollen.
How efficient is Eucalyptus where water use is concerned?
Eucalyptus evolved in the arid lands of Australia and is a very efficient water user. In fact, Eucalyptus uses less water per unit weight of biomass than many other trees and agricultural crops (Chaturvedi, 1987, Davidson, 1995). The annual rainfall in the U.S. South is similar to regions of Brazil where this type of Eucalyptus is grown, and there have been no known problems with water. Forest hydrology experts in the U.S. estimate that a plantation of fast growing Pine would use approximately the same amounts of water as a Eucalyptus plantation.
Is Eucalyptus extremely flammable?
As with any forest species, the nature, frequency and season of occurrence of fire are dependent on a variety of factors such as the accumulation of potential fuels in forests if these have not been managed. What that means is that these other forest variables are the primary determinants of fire risk, not the particular species of trees — such as Eucalyptus — that is planted.
While some groups have said that Eucalyptus is very flammable, the idea that Eucalyptus fires occur more often than in other tree stands is completely unfounded; this myth has likely come from the high profile wildfires in California and Australia where Eucalyptus has been extensively planted. According to the United States Forest Service, the cause of the fires in California can be attributed to four primary reasons: 1) fire suppression policies that allowed the accumulation of fuel in the form of fallen leaves, branches, and excessive plant overgrowth in forest and wildland areas; 2) increasingly dry, hot weather; 3) changing weather patterns across the U.S.; and 4) increased residential development in the wildland/urban interface. http://www.smokeybear.com/wildfire-science.asp
Is there any expected negative long-term impact on soil from growing Eucalyptus?
No, there is not an expected negative long-term impact on soil where Eucalyptus is grown. In fact, when planted on marginal agricultural lands or other areas with degraded soils, Eucalyptus planting can actually improve soil fertility. Eucalyptus nutrient use is efficient, and consumption is lower or comparable to other planted tree species and agricultural crops. In Brazil, which has the longest history with Eucalyptus as a plantation crop, we have seen examples of consistent or increased yields of Eucalyptus over successive rotations.
How does Eucalyptus interact with other species of trees or plants that are grown near it?
It is a common myth that Eucalyptus harms other plants or trees grown near it. This phenomenon is known as allelopathy, which is defined as the ability to inhibit the growth of competitors. Many plants do have this ability, but tests on different Eucalyptus species show that they are no more allelopathic than many other trees such as Maple, Hackberry, Southern Waxmyrtle, American Sycamore, Cottonwood, Black Cherry, Red Oak, Black Locust, Sassafrass and American Elm.
Do stands of Eucalyptus favor wildlife?
The understory of plantation forests, as well as the Eucalyptus trees themselves, provide habitat for a variety of mammals, birds and amphibians. In fact, plantation forests of Eucalyptus can provide a more long-term and stable habitat than annual crops where the land is disturbed multiple times throughout the year.
Where in the U.S. is Eucalyptus grown?
Eucalyptus has been grown in California since 1856. The California Board of Forestry distributed free Eucalyptus seedlings from 1886-1888. In 1877, more than 44,000 Eucalyptus were planted in Alameda County. Extensive plantations were introduced near Santa Barbara in 1872 and 1873 by T.J. Gillespie for Gillespie Lumber Company. In total, there are an estimated 65 varieties of Eucalyptus found in California.
Even though the species has naturalized in some of California’s microclimates that are particularly well suited to the species, only Eucalyptus camaldulensis and E. globulus are listed on the California Invasive Plant Council Inventory Database. E. camaldulensis is listed as “limited invasiveness” in “southern urban areas,” and E. globulus as moderate in coastal areas only.
Will native wildlife be able to make a habitat from Eucalyptus plantations?
Yes, Eucalyptus plantations can provide a habitat for native wildlife. While many studies report lower biodiversity in plantation forests compared to natural forests, biodiversity is often higher in plantation forests than on lands used for other activities such as agriculture. Additionally, Eucalyptus trees aren’t cut down and replanted every year, making a more stable habitat for a longer period of time to support wildlife.
How will Freeze Tolerant Eucalyptus impact native wildlife?
We do not expect Freeze Tolerant Eucalyptus to make any significant impact on native wildlife. Freeze Tolerant Eucalyptus would not likely replace native forests. Rather, the Eucalyptus is likely to be planted in areas of existing managed forests, agricultural lands or currently fallow lands. Forest landowners who plant Eucalyptus for purpose grown wood are expected to use established forestry practices that take into account wildlife and other societal values. As such, it is not expected that Freeze Tolerant Eucalyptus would have any significant impact on native wildlife.
How can we be certain that Eucalyptus will not cross-pollinate with another Eucalyptus?
Typically in nature, Eucalyptus species can only cross with other species that are very closely related. Other Eucalyptus grown in the South are quite distantly related, hence they are not able to cross-pollinate. In addition, different species of Eucalyptus flower and bloom at different times which serves as another natural barrier for cross-pollination between Eucalyptus species. Also note that ArborGen Freeze Tolerant Eucalyptus does not produce pollen.