Report to the Republic of Palau: 2008 update on Invasive Plant ...

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Invasive species already widespread in <strong>Palau</strong> A number <strong>of</strong> serious invasive species are already widespread in <strong>Palau</strong>. Eradication or extensive control is out <strong>of</strong> <strong>the</strong> question for <strong>the</strong>se species, but <strong>the</strong>y may still warrant control in sensitive, natural and protected areas such as parks and reserves. Adenan<strong>the</strong>ra pavonina (telengtúngd, telentundalel, coral bean tree), invasive in secondary forests throughout <strong>the</strong> Pacific, is common in <strong>Palau</strong>. Although <strong>the</strong> seeds are eaten and many people consider it native, it was introduced. Coral bean has <strong>the</strong> ability <strong>to</strong> over<strong>to</strong>p many native trees and eventually form monospecific stands. Trees produce large quantities <strong>of</strong> seed and <strong>the</strong> tree will grow on a variety <strong>of</strong> soils. While it seems <strong>to</strong> be scattered at <strong>the</strong> present time, if its behavior on <strong>Palau</strong> is similar <strong>to</strong> o<strong>the</strong>r Pacific locations, it may eventually become much more widespread. Its weed risk assessment score is 7, rating it “high risk”. Allamanda cathartica (allamanda, yellow trumpet vine) is widely planted and naturalized. It is becoming invasive in nor<strong>the</strong>rn Queensland, Australia, and Papua New Guinea. The 2002 survey noted its presence in forest and savanna in central Babeldaob. It has a risk assessment score <strong>of</strong> 8, “high risk”. Arundo donax (giant reed) is found in moist areas and along ditches and riverbanks. “Once established, giant reed can form huge clones, sometimes covering hundreds <strong>of</strong> acres. It is highly flammable and re-sprouts quickly after burning. Fires help transform communities <strong>of</strong> native plants in<strong>to</strong> solid stands <strong>of</strong> giant reed, changing riverbank forests from flood- <strong>to</strong> fire-defined habitats” (Bell, 1996). It spreads by means <strong>of</strong> rhizomes and fragments <strong>of</strong> stems, <strong>of</strong>ten carried by water and has a weed risk assessment score <strong>of</strong> 12, “high risk”. Chromolaena odorata (ngesngesil, chromolaena, Siam weed) is a highly invasive pan-tropical weed that is widespread in <strong>Palau</strong>. It has small, wind-dispersed seeds that can also travel on boots, clothing or used cars or equipment. The biological control agents Pareuchaetes pseudoinsulata (a moth) and Cecidochares [=Procecididochares] connexa (Tephritidae) (a gall fly) have been introduced <strong>to</strong> <strong>Palau</strong> (Muniappan and Marutani, 1991). Pareuchaetes pseudoinsulata is not established. Cecidochares connexa is established in Koror State and Babeldaob and appears <strong>to</strong> be reducing flowering and plant vigor. In addition <strong>to</strong> <strong>the</strong> widespread infestations <strong>of</strong> chromolaena on <strong>the</strong> main islands, a small infestation was found in 2002 on Ngidech in <strong>the</strong> Rock Islands and is in <strong>the</strong> process <strong>of</strong> being eliminated. An Australian risk assessment gave this species a score <strong>of</strong> 34, indicating that it is <strong>of</strong> very high risk. Clerodendrum quadriloculare (kleuang, bronze-leaved clerodendrum) was common in 2002 but has been reduced since that time by control action. The species is <strong>of</strong>ten planted as an ornamental but is no<strong>to</strong>rious for being a prolific producer <strong>of</strong> root suckers and, in fact, <strong>the</strong> plant is easily propagated by means <strong>of</strong> root cuttings. It has <strong>the</strong> ability <strong>to</strong> invade intact or relatively intact native forests. It has become widespread on Pohnpei, Federated States <strong>of</strong> Micronesia. In Hawai‘i it is becoming a problem ornamental, producing numerous root suckers that appear some distance from <strong>the</strong> parent plant. There are still occasional infestations in yards and along roadsides. The weed risk assessment for this species indicates that it is “high risk”, with a score <strong>of</strong> 11. 10
Clidemia hirta (kúi, Koster’s curse) is a serious problem species in Hawai‘i and o<strong>the</strong>r locations, including Fiji, <strong>the</strong> Solomon Islands and Vanuatu. It is a very serious weed <strong>of</strong> <strong>the</strong> forest unders<strong>to</strong>ry on a number <strong>of</strong> tropical islands. It is shade <strong>to</strong>lerant, is spread by birds and has <strong>the</strong> potential <strong>to</strong> invade all <strong>the</strong> forests <strong>of</strong> <strong>Palau</strong>. It was thought <strong>to</strong> be confined <strong>to</strong> a single area on Babeldaob near <strong>the</strong> Forestry Station at Nekken (in <strong>the</strong> vicinity <strong>of</strong> old Oikull Village in Airai), but during <strong>the</strong> 2002 survey a single plant was found on <strong>the</strong> hill above <strong>the</strong> radio <strong>to</strong>wer on Malakal. That plant was destroyed and <strong>the</strong> area searched for o<strong>the</strong>rs. This area was revisited in <strong>2008</strong> and no new plants were noted. The weed risk assessment for this species is “high risk”, with a score <strong>of</strong> 27. A biological control agent, Leothrips urichi, was introduced <strong>to</strong> <strong>Palau</strong> in <strong>the</strong> late 1960’s, is established and effective in open areas but largely ineffective in forested habitats. While it is mostly used as a cultivated ornamental, a large number <strong>of</strong> escapes <strong>of</strong> Dieffenbachia seguine (spotted dieffenbachia, dumb cane) were noted, probably as a result <strong>of</strong> discarded plants or cuttings. This species can be invasive and difficult <strong>to</strong> remove, particularly along streams and o<strong>the</strong>r moist areas. It has become a major problem in this regard in American Samoa and Samoa. Where found outside <strong>of</strong> cultivation, particularly in wet areas, this species should be removed, as it reproduces vegetatively and can thrive in <strong>the</strong> dense shade <strong>of</strong> an intact native forest canopy, crowding out o<strong>the</strong>r species. The weed risk assessment score for this species is 7, “high risk”. Dissotis rotundifolia (dissotis, pink lady) was seen in cultivation and infestations are common, particularly on Babeldaob. It can form a dense mat in <strong>the</strong> forest unders<strong>to</strong>ry, crowding out or excluding o<strong>the</strong>r species. This behavior was seen in Samoa. It is a problem species as well in Fiji, French Polynesia and Hawai‘i. Since it can reproduce vegetatively, mowing or slashing can spread it more widely or lead <strong>to</strong> very dense stands. Its weed risk assessment score is 10, “high risk”. Falcataria moluccana [=Paraserian<strong>the</strong>s falcataria] (ukall ra ngebard, Moluccca albizia) is most common in central Babeldaob although it was also seen on Koror. Many <strong>of</strong> <strong>the</strong> trees are quite large and apparently have been present for some time. Some <strong>of</strong> <strong>the</strong> older trees have recently died. Some younger trees were noted becoming established in disturbed areas on <strong>the</strong> edge <strong>of</strong> <strong>the</strong> forests. It is much more aggressive and extensively naturalized on Pohnpei (Federated States <strong>of</strong> Micronesia), Tutuila (American Samoa), Kauai (Hawaii) and Tahiti (French Polynesia). It has a weed risk assessment score <strong>of</strong> 8, “high risk”. Lantana camara (lantana) is common, both cultivated and naturalized. Wild plants seem <strong>to</strong> be more common on <strong>the</strong> nor<strong>the</strong>rn part <strong>of</strong> Babeldaob and on Koror and Angaur. A pink form is prevalent in nor<strong>the</strong>rn Babeldaob and Angaur while a red form is present in Koror and surrounding areas. At least two biological control agents have been introduced, but <strong>the</strong>ir present status is unknown. In any case, Lantana doesn’t seem <strong>to</strong> be a big problem in <strong>Palau</strong> at <strong>the</strong> present time, although its weed risk assessment score is 21, “high risk”. Leucaena leucocephala (telengtungd, leucaena) is very common, as on most Pacific islands, but it is not as prevalent in <strong>Palau</strong> as it is in many o<strong>the</strong>r locations. It is a prolific seed producer, with a weed risk assessment score <strong>of</strong> 15, “high risk”. Mimosa diplotricha [<strong>of</strong>ten incorrectly called M. invisa] (mechiuaiuu, giant sensitive plant) is a particularly nasty plant covered with brittle thorns, forming dense tangles that are difficult <strong>to</strong> 11
Page 1: Report to<
Page 4 and 5: Pulo Ana ..........................
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Page 9 and 10: of known or potent
Page 11 and 12: Leucas lavandulifolia [voucher 9929
Page 13 and 14: Rock Islands We were especially int
Page 15: 2. Species that are subjects <stron
Page 19 and 20: Timonius timon (Liberal) is widespr
Page 21 and 22: cultivation but this tree-climbing
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Page 25 and 26: Australia). Its weed risk assessmen
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Page 29 and 30: Cestrum diurnum (day cestrum, day j
Page 31: Piper auritum (eared pepper, also c
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Page 36 and 37: Agriculture invasive species <stron
Page 38 and 39: Table A. Priority species for exclu
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Page 61 and 62: Appendix 1. Invasive plant species
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Table 3. Other spe
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Table 4. Other inv
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Table 4. Other inv
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Appendix 2. Invasive plant species
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Table 1. Invasive plant species <st
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Table 2. Other inv
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Table 2. Other inv
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Table 2. Other inv
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Appendix 3. Invasive species presen
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Scientific Name Hawai'i Guam Yap Pa
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Table 1. Invasive species o
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Appendix 5. Other
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Table 1. Other inv
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Table 2. Other inv
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Table 2. Other inv
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Table 3. Other inv
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Table 5. Other inv
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Table 6. Other inv
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Table 8. Other inv
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Appendix 6. Presence of</st
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Table 2. Species of</strong
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Table 1. Other spe
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Table 2. Other spe
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Table 3. Other spe
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Table 3. Other spe
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Table 4. Other spe
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Table 4. Other spe
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Table 9. Other spe
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Appendix 8. Risk assessments for in
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Synonym Listed as Family Gomphrena
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Fosberg, F. R., and M.-H. Sachet. 1
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Stoddart, D. R. 19
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Report to the Republic of Palau: 2008 update on Invasive Plant ...

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