Leucaena leucocephala is a long-lived shrub native to
Central and South America. It is a tropical plant and can tolerate a range of
rainfall from 500-3500mm and withstands strongly seasonal (6 to 8 month) dry
climates. Although it is an invasive species it has been introduced due to its beneficial
qualities. Its major use being a nutritious forage tree for cattle and livestock,
but other positive uses are providing firewood, timber, shade and erosion
control. Also hedges can be useful as windbreaks and firebreaks (Shelton H.K,
Brewbaker, JL, 2014)
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Problems with Leucaena can arise when it is not heavily
grazed or controlled as it can grow up to 8m and grows too tall for cattle to
eat. It then can spread quite rapidly into water ways and creek lines as well
as hinder movement of wildlife. It can form dense thickets which are reported to
be replacing native forest in some areas threatening endemic species. These thickets
can render some areas unusable and inaccessible. It is a declared weed in New Guinea, Hawaii, and
western Polynesia and in the United States however it is not a declared plant
in Qld under the land protection (pest stock route management) act 2002 (Department of Agriculture, fisheries and Forestry)
A study was conducted in Thailand on the role Leucaena
played on tree regeneration in the Khao Phuluang Forest. The results suggested that
the leucaena restricted the native forest by its invasive habit and reduces
light transmittance to the forest floor (Marod D, et al, 2012).
My understanding is that as long as this shrub is grazed and kept under control and confined to one area it can be used to an advantage.
References:
Department of Agriculture, fisheries and forestry, Biosecurity Queensland, Feburary 2014.
Marod D, Duenkae U, Sungkaew S, Wachrinret C, Asanok L,
Klomwattankul N, 2012, ‘The influences of an invasive species (Leucaena leucocephala) on tree
regeneration in Khe Phulary Forest, Northeastern Thailand. Forest Biology, vol. 46, pp. 39-50
Shelton H.M, Brewbaker J.L, 2014
http://www.fao.org/ag/Agp/agpc/doc/Publicat/Gutt-shel/x5556e06.htm
This a really good example of a trade-off – good benefits on one side, nasty costs on the other. While it has so many benefits, surely there are other plants in Australia that have the same benefits (and are also not invasives!)? How is it that this species can spread rapidly if left undergrazed? Why is it that invasives always seem to do better than native species? Interesting information.
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