Report on invasive plant species in American Samoa
Download, read and print this report in PDF format
Dangerous species not known to be in American Samoa
Native and naturalized species exhibiting aggressive behavior
Strategies for dealing with invasive species
Appendix 1 References
Appendix 2 Species by category
Appendix 3 Invasive and potentially invasive species present on Tutuila
Appendix 4 Invasive and potentially invasive species present on Ofu
Appendix 5 Invasive and potentially invasive species present on Olosega
Appendix 6 Invasive and potentially invasive species present on Tau
Observations on invasive plant species in American Samoa
James C Space and Tim Flynn
U.S.D.A. Forest Service Pacific Southwest Research Station Institute of Pacific Islands Forestry Honolulu, Hawaii, USA
4 January 2000
|
4 January 2000
Observations on invasive plant species in American Samoa
James C Space and Tim Flynn (1)
This is a continuation of the survey of islands in Micronesia and American Samoa for invasive plant species requested by the Pacific Islands Committee, Council of Western State Foresters. A survey of selected Micronesian islands was conducted in 1998 and was discussed in a previous report (2). This report is based on perceptions gained from a trip to American Samoa from 16 to 23 July 1999, including the islands of Tutuila, Ofu, Olosega and Tau. The objectives were three-fold: (1) To identify plant species on the islands that are presently causing problems to natural and semi-natural ecosystems; (2) to identify species that, even though they are not presently a major problem, could spread more widely or spread to other islands where they are not present, potentially causing problems; and (3) to confirm the absence of species that are a problem elsewhere and, if introduced to American Samoa, could be a threat there.
During our visit local experts showed us sites of known infestations (3). We also had available copies of various botanical and weed surveys conducted in the past (see Appendix 1, References). A weeklong trip does not permit an exhaustive survey of the weed biota of the islands. However, the intent was to conduct an overall survey. Surveys of individual species or sensitive areas (such as the National Park of American Samoa) can and should be conducted as needed. This report summarizes our findings and makes some suggestions for further action.
For convenience and to be consistent with the Micronesia report, invasive species occurring in or of threat to the American Samoan islands have been grouped into five categories:
1. Species that are invasive elsewhere in similar ecosystems but were not seen on our visit and are not reported in the literature as being present in American Samoa (174 species).
2. Species that are invasive elsewhere and are also invasive or potentially invasive in American Samoa (20 species).
3. Species that are not known to be particularly invasive elsewhere but have the potential to be invasive in American Samoa (5 species).
4. Species that are invasive or weedy elsewhere and are common or weedy in American Samoa (80 species).
5. Native species that exhibit aggressive behavior (7 species).
These species are listed in Appendix 2. In addition, species are listed by location within American Samoa in Appendix 3. Additional information about each species is located on a World Wide Web site, http://www.hear.org/pier/. Copies of this web site are also available for installation on individual computers for rapid access.
There are numerous species that are invasive weeds in gardens, fields, and pastures and along roadsides but dont seem to pose a particular threat to wildland ecosystems. These species are not included.
1. Dangerous species not known to be in American Samoa
While there are some serious or potentially serious weed species in American Samoa, some other major pests have not yet arrived. The worst of these include the following:
Cecropia obtusifolia and C. peltata, invasive tree species that are a problem in Hawaii and French Polynesia, respectively.
Chromolaena odorata (Siam weed), a highly invasive pan-tropical weed. It is present in a number of islands in the Marianas and Micronesia, as well as Papua New Guinea, the Philippines and Australia.
Coccinia grandis (ivy or scarlet gourd), a smothering vine that is showing potential for serious damage to the forests of Saipan. The vines climb over trees and form such dense cover that the forest underneath is completely shaded out and destroyed. It is also invasive in Guam and Hawaii and recorded in the literature as being present in Fiji, Tonga and Vanuatu. Whistler reports that it is present in Samoa, and this close proximity makes this species a special threat to American Samoa.
A rubber tree, Funtumia elastica (African rubber tree, pulu vao), has been reported by Whistler (1988) as being present and invasive in Samoa. As far as is known, this species is not yet in American Samoa, although another rubber tree (Castilla elastica, Panama rubber tree or pulu mamoe) is present (see below). F. elastica should be a priority species for exclusion or, if found, eradication.
Miconia calvescens (the purple plague), which has caused serious damage to the ecosystem of Tahiti in French Polynesia. It has also escaped in Hawaii and is the subject of an intensive and costly eradication effort there. Recently it was discovered in Queensland, Australia, and has spread to other islands in French Polynesia.
Melinis minutiflora (molasses grass), a species that is both invasive and causes a serious fire hazard. It has fostered the establishment of fire regimes on many islands where it has been introduced. It is cited in the literature as being present but not weedy in Samoa, and is present on a number of other Polynesian islands. It is not recorded from American Samoa, but even though it may not be causing problems in Samoa, it is a species that it would be desirable to exclude, given its reputation.
Passiflora tarminiana (banana poka, formerly known as P. mollissima), a smothering vine that is a problem in Hawaii and New Zealand.
Pennisetum setaceum (fountain grass), another grass that is a major problem in Hawaii. It is recorded as being present in Fiji.
Psidium cattleianum (strawberry guava), a small tree that forms dense thickets and is a major problem species in Hawaii, Tahiti and elsewhere.
Rubus species (blackberries and raspberries), many of which are pests.
Tibouchina herbacea (glorybush or cane ti), another species that is a major problem in Hawaii.
And the above are just the worst of the lot. In addition, all grasses, all members of the Melastomataceae family, and all Ligustrum, Passiflora or Rubus species not already present should be highly suspect and should be proven benign before they are allowed to be introduced.
The best indicator that a species might be invasive is the fact that it is invasive elsewhere. However, each island ecosystem is unique, and invasiveness cannot be predicted with certainty. A good strategy is to be extremely cautious and exclude those species known to be invasive or weedy elsewhere (although an even better strategy, now being adopted by countries such as Australia and New Zealand, is to exclude all species not shown by risk analysis to be of negligible risk). Known problem species that have the potential to cause problems in tropical island ecosystems are listed in Appendix 2, Table 1. These species should be excluded through plant quarantine and, if establishment is detected, promptly evaluated for eradication.
In addition, there are a number of species that are present on Tutuila that are not present on Ofu, Olosega, or Tau (see Appendix 3). Measures that limit the spread of invasive species to these islands, or prompt eradication, may keep these islands free from some pests already on Tutuila.
Some known invasive plants that are causing trouble in similar ecosystems have been introduced into American Samoa (see Appendix 2, Table 2). Some of them are already causing problems while others are not. Some are cultivated plants that have not (yet) escaped and their potential for causing damage is so far unknown. However, one of the best predictors of invasiveness is the behavior of the species elsewhere, and these are known troublemakers.
Adenanthera pavonina (the coral bean tree, lopa) is invasive in secondary forests, but also has the ability to become much more widely established, both on Tutuila and the Manuas. On Ofu it was invading relatively intact forest margins, producing what seemed to be an overwhelming number of seedlings. It has probably spread too widely for anything but local control in sensitive areas but this should certainly be explored. Unfortunately, many people roast and eat the seeds, refering to them as "Samoan peanuts", and don't view the tree's presence as a problem.
Antigonon leptopus (chain of hearts) is reported to be present on Tutuila. This climbing vine has become a widespread pest on Guam. It has not yet escaped cultivation in American Samoa. It should be observed for invasive behavior on Tutuila and excluded from the outer islands.
Bryophyllum pinnatum (life plant), probably also an escape from cultivation, was seen on both Tutuila and Olosega. It reproduces vegetatively and may be invasive on the forest floor.
The Panama rubber tree (Castilla elastica, pulu mamoe), previously reported to be highly invasive in Samoa, has become established on Tutuila near Maloata. It is also reported to be found near 'Ili'ili. This species has the ability to become established in intact forests, posing a threat to the native forests. It presently doesn't seem to be too widespread and might be a good candidate for eradication or control.
Cinnamomum verum (cinnamon, tinamoni) is actively naturalizing in secondary forests in several locations on Tutuila. It shows great potential for becoming a major invasive species. It should be evaluated for control measures and should be excluded from the Manua islands.
Clerodendrum chinense (Honolulu rose, losa Honolulu) is prevalent on both Tutuila and the Manua Islands. This shade-tolerant species reproduces from root suckers.
Clidemia hirta (Kosters curse) is present on Tutuila and the Manua Islands (particularly on Ofu and Tau). It is scattered and localized on Olosega. This species is a serious problem species in Hawaii. The thrips Liothrips urichi was introduced as a biological control agent on Tutuila about 25 years ago and seems to be giving a reasonable level of control. It was recently introduced to Tau. The agent could also be introduced to Ofu/Olosega. Work is under way on additional bio-control agents in Hawaii.
Costus speciosus (crepe or wild ginger) was seen naturalizing on Tutuila. This is a potentially troublesome species that reproduces vegetatively and can grow in either full sun or shaded forest understories. At least in the A'oloau area of Tutuila it seemed to thrive in areas of disturbance (in this case an abandoned orchard that was being turned into pasture). It is a weedy species in French Polynesia.
Dieffenbachia seguine (spotted Dieffenbachia or dumb cane), which probably escaped from cultivation as an ornamental, was seen in a number of locations on Tutuila, including the National Park of American Samoa. This is potentially a very bothersome species, as it reproduces vegetatively and can thrive in the dense shade of an intact native forest canopy.
An isolated infestation of a Hedychium sp. (ginger) was seen on Tau that should be promptly eradicated.
Imperata cylindrica (cogon grass) has been reported to be present in American Samoa. We did not see it, and it may not be a problem in American Samoan ecosystems, but this is a very invasive species elsewhere and, if found to be present, should be closely monitored for spread.
Lantana camara (lantana, latana) was observed being grown as an ornamental on Tutuila and Tau. Although a serious pest elsewhere in the Pacific (and throughout the tropics), it does not seem be a problem here, at least yet.
Leucaena leucocephala (fua pepe), as is the case throughout most of the Pacific, is prevalent on all the islands.
A Ligustrum (L. sinense?) was noted in cultivation on Tutuila. Privets are notorious invaders and it would be desirable to eradicate any examples and exclude them in the future.
Lonicera japonica (Japanese honeysuckle) was also seen in cultivation on Tutuila and Tau. This is another well-known invader. If possible, it should be eradicated or at least further plantings discouraged and the present ones monitored for spread.
Merremia peltata (fue lautetele) is quite invasive on Tutuila and is also found on Tau. According to local sources, it was introduced about 1970, although this may just have been the time it became a noticeable problem. It is apparently a native or an early introduction throughout much of Melanesia, Polynesia and Micronesia, but its aggressive behavior has been noted elsewhere. Not seen on Ofu and Olosega.
Mikania micrantha (mile-a-minute weed, fue saina) has become well established as a major pest of disturbed areas on all the major American Samoan Islands.
Mimosa diplotricha [=invisa] (giant sensitive plant, vao fefe palagi) is established on Tutuila and Ofu, although not widespread. Given its limited extent on Ofu, it is a prime candidate for eradication there. It should be excluded from Olosega and Tau and promptly eradicated if found. A biological control agent is available that might also be employed if M. invisa becomes more widespread. However, this agent (Heteropsylla spinulosa) will not eradicate the plant and is most effective in open areas, such as pastures.
Paraserianthes falcataria [Falcataria moluccana] (tamaligi palagi) is widespread on Tutuila. However, it may be a candidate for exclusion or control on the Manua Islands.
Spathodea campanulata (African tulip tree) is present in cultivation on Tutuila. This tree has become a major problem in Fiji, the Hawaiian Islands and some other places. It is a problem species in Samoa and thus should be closely monitored for spread from its present locations in American Samoa. It was not observed on the Manua Islands and it would be good to exclude it from there.
Syngonium angustatum, a climbing aroid, was seen spreading in the National Park of American Samoa along the Mount 'Alava trail. It was also noted in many areas bordering habitation sites (e.g. the Government housing area). This is an especially aggressive plant that has the ability to tolerate low light conditions such as those found in relatively intact forest settings. Along one area of the Mount 'Alava trail it completely dominated the groundcover layer, seemingly to the exclusion of all other species. It also has a tendency to climb and in fact was covering the trunks of most of the mature trees in the area. This species would probably require hand or mechanical removal, followed by periodic checks, for eradication. Syngonium is able to reproduce from a single node and almost certainly bits and pieces of the stems would be overlooked.
A few species that have not been particularly invasive elsewhere have the potential to become problems in American Samoa (Appendix 2, Table 3).
Clerodendrum quadriloculare is suspicious because it appears to have the ability to invade intact or relatively intact native forests. This species is notorious for being a prolific producer of root suckers and in fact the plant is easily propagated by means of root cuttings. A dense, monospecific understory of this species was seen growing in full shade beneath the forest canopy on Pohnpei, making it a likely candidate to invade intact or only slightly disturbed native forest stands. Specimens observed on Tutuila and Tau were cultivated ones in yards, but this species should be monitored for possible naturalization. If so, naturalized populations should be promptly eradicated.
Desmodium nicaraguense (synonym D. rensonii) has been distributed as a forestry tree but shows signs of naturalizing. It should be closely monitored and, if necessary, naturalizing populations controlled.
Flemingia macrophylla has likewise been distributed as a forestry tree and may naturalize. Again, close monitoring and, if necessary, control is in order. Another Flemingia species, F. strobilifera, is invasive on Tahaa and Raiatea (Society Islands) and naturalizes along roadsides on Nuku Hiva (Marquesas), French Polynesia, as well as in the Hawaiian Islands.
Sambucus mexicana (Mexican elder) is fairly common on Tutuila, both as an ornamental and naturalized in open areas. It is also present on Tau.
The white-flowered form of Sesbania grandiflora (hummingbird tree) has naturalized in localities where it has been planted on Tutuila. It was originally introduced as a possible fuelwood tree, but it is not resistant to hurricanes. If not too widespread, it may be a candidate for control or eradication.
A large number of other common or weedy introduced species were noted. Many of these species, which might best be termed aggressive weeds, are mostly prevalent along roadsides or on disturbed sites, although some species, particularly alien trees, can gradually spread into forested ecosystems. In the case of vines and plants that form dense ground cover, the regeneration of native species can be inhibited.
Some of these species could become a problem in the future, since there is often a long lag time between introduction and when a species begins to cause serious impacts. These species (listed in Appendix 2, Table 4) should be seriously evaluated for inter-island quarantine to confine them to the islands where they are presently located or to eradicate them if they become established elsewhere.
Potentially invasive tree species include Acacia auriculiformis (earleaf acacia), A. mangium, Ceiba pentandra (kapok, vavae), Schefflera actinophylla (octopus tree), Syzygium jambos (malabar plum), Samanea saman (monkeypod), Tabebuia heterophylla (pink trumpet tree) and Tecoma stans (yellow bells).
Passiflora maliformis (pasio) is reported to be in American Samoa (not seen). This species is on the French Polynesia noxious weed list.
An isolated infestation of Solanum torvum (prickly solanum) is located on Tutuila and should be eradicated.
Likewise, an infestation of Ipomoea alba on Tutuila should be eradicated.
A wide variety of introduced grasses have become established, the most aggressive of which include Cenchrus echinatus (bur grass, vao tuitui); Cynodon dactylon (Bermuda grass); Paspalum spp., including P. conjugatum (Hilo grass, vao lima), P. dilatatum (Dallis grass), P. fimbriatum, and P. urvillei (Vasey grass); Pennisetum pupureum (elephant or napier grass) and Sorghum halepense (Johnson grass) (although there is some question as to the identify of this last species Whistler (1988) classifies it as S. sudanense, a less aggressive species).
Other widespread weedy species include Indigofera suffruticosa (indigo), Mimosa pudica (sensitive plant, vao fefe), Passiflora foetida (love-in-a-mist, pasio vao), Psidium guajava (guava, ku'ava), Stachytarpheta cayennensis [urticifolia] (blue rat's tail, mautofu tala) and Wedelia [Spagneticola] trilobata (Singapore daisy, ateate). Derris malaccensis (New Guinea creeper, 'ava niukini) is present and invading lowland coastal forests on Tutuila, Aunu'u, Ofu and Olosega.
A number of other species present to some degree in American Samoa have bad reputations elsewhere. These should be monitored for invasive behavior and evaluated for quarantine. They include bamboos (Bambusa and other bamboo species), Cestrum diurnum (day cestrum) and C. nocturnum (night-flowering cestrum, queen of the night, teine o le po, ali'i o le po), Duranta repens (golden dewdrop), Hedychium spp. (gingers), Hemigraphis alternata, Hyptis pectinata (comb hyptis or mint weed), Ricinus communis (castor bean) and Schinus terebinthifolius (Christmasberry).
5. Native and naturalized species exhibiting aggressive behavior
Some native species (or early introductions) exhibit characteristics that could make them problem species if they are introduced to islands where they are not present. These species are listed in Appendix 2, Table 5.
Strategies for dealing with invasive species
The first line of defense against invasive species is to keep them out. Control at ports of entry is essential, and land management officials should work closely with plant protection and quarantine officials to make them aware of known and potential invasive plant species. Plant quarantine officers are familiar with most agricultural pests, but they may not be aware of some of the pests that threaten wildland ecosystems. In cooperation with the plant quarantine organization, a list of noxious species to be excluded should be developed and exclusion of these species should be backed by the force of law and regulation. Better yet is to go to the approach recently adopted by Australia and under serious consideration by a number of other counties. That is to exclude all alien species not shown to be of negligible risk. Risk assessment and management techniques can be used to assess the likelihood and effects of possible introductions and to develop exclusion and eradication strategies.
Other exclusion measures that would be desirable to put in place include:
Education of the public about the danger of introductions and encouraging the use of native species can be helpful. What may just be a pretty flower to be planted in a yard or garden can turn out to be an invasive species. It is particularly important to work with local nurseries and botanical gardens, as these are often sources of new introductions. A positive approach is to work together to develop a "white list" of both native and non-native species that the public can be encouraged to plant.
The public also needs to understand that the immediate eradication of a small area of a problem species, even if it involves the use of herbicides, may be better than living with a problem species forever. There are many instances where you hear people say "I wish we'd taken action when this pest was first noticed". It may even be worthwhile to take people to a place where they can be shown the full extent of the problem if the infestation is allowed to spread so that they will accept and support eradication. For example, anyone visiting Tahiti would very likely come away convinced that Miconia calvescens is an ecological disaster and that it should be prevented from becoming established on other Pacific islands.
The public should also be encouraged to report suspicious plants. Public service announcements on television or radio or newspaper articles can encourage this. Funding can be requested to prepare PSA's or "wanted" posters. Prompt follow-up to public reports is essential to maintain the credibility of such a program.
Land managers and extension agents should be alert to new species that exhibit invasive behavior. Often, these species first show up in urban or farm areas because they are usually introduced by people and tend to become established in disturbed areas. Suspicious plant species should be promptly reported. A scouting program should be established where scheduled surveys are made for new or expanding infestations. A formal evaluation should be requested for any new species that appears to be invasive or is known to be invasive elsewhere. This evaluation should be by an expert who is familiar with the species and methods for its eradication or control and can recommend further action. Prompt action is essential, since once a species becomes widespread, control or eradication can be extremely costly or impossible.
It is also very helpful to have laws and regulations in place to aid in dealing with new introductions. This includes the ability of government to require the control of noxious species on private lands or to take action on private lands if the landowner cannot be located or does not take prompt action. Provision for emergency funds to deal with immediate problems should also be in place. Model laws and regulations can be obtained from states and countries that have implemented them.
The American Samoan government is encouraged to take advantage of the Federal assistance programs in dealing with invasive plant species. American Samoa is already utilizing cost-share funding to provide locally available expertise in forest health protection. Experts are also on call from the Forest Services Forest Health Protection staff, or they can arrange for expert consultation. Finally, cost-share funding can be requested to deal with forest health problems, including plant pests, under the Cooperative Forestry and Hawaii Tropical Forestry Recovery acts. Funding is subject to recommendations resulting from a professional evaluation of the problem and the overall availability of funds. Funding also tends to be prioritized based on an economic evaluation of cost-effectiveness, so rapid eradication of a pest species while it is still confined to a small area would undoubtedly take precedence over the chronic problem of a species that has escaped control.
In addition to the above strategies, we offer the following specific recommendations.
Make every effort to keep out all the species listed in Appendix 2, Table 1. These are known invasive species elsewhere, and there is no sense in running the risk that they will act the same in American Samoa. As we are able to gather more information on other species that might threaten tropical island ecosystems we will add them to the list. For those with Internet access, additional information and new listings can be found at http://www.hear.org/pier/.
Take special measures to keep Coccinia grandis, Miconia calvescens and Psidium
cattleianum out, to monitor for their occurrence, and to eradicate them
immediately if found. Coccinia grandis has proven highly
invasive in Saipan, is present and invasive in Hawaii, and is present in Samoa.
Given how Miconia has behaved in Tahiti and Hawaii, it could be an ecological
disaster if it is introduced. Psidium cattleianum is a
serious problem in Hawaii and a number of other tropical islands.
Since there is so much traffic to Samoa from Hawaii, where these species are present, it would be highly desirable to institute some special measures to prevent their introduction from that source (similar measures would be desirable for French Polynesia, although there is apparently little traffic from there). At a minimum, quarantine officers should be alert to people who might have been in the woods or rural areas in Hawaii, especially on the Big Island, and inspect their shoes or boots for seeds. Any trucks or equipment coming from Hawaii that have been used in rural areas must be power washed or steam cleaned. Warning posters should be produced to alert the public and encourage reporting of any introductions (fortunately, these plants are quite distinctive and easily identified). Any infestations picked up from public reporting or scouting should be promptly eradicated before the plants set seed.
Perhaps a procedure could be established that begins the quarantine/plant inspection process in Hawaii similar to that for people travelling to the mainland U.S. In this case all baggage heading for or through American Samoa would be subject to inspection for target noxious species before it left Hawaii.
In addition, there are other notorious weeds that are not yet in American Samoa, including Chromolaena odorata, Cecropia obtusifolia and C. peltata, Melinis minutiflora, Passiflora tarminiana, Pennisetum setaceum, Rubus spp., Tibouchina herbacea, Ligustrum spp. and Passiflora spp. Quarantine measures should be instituted to keep them out and they should be eradicated immediately if found.
For species listed in Appendix 2, Tables 2 and 3, take all reasonable precautions to prevent movement to islands where they are not present, be vigilant to detect introductions on these islands, and take prompt action if they are found.
Species listed in Appendix 2, Table 4 are pests and, although they may not be presently causing serious damage to wildland ecosystems, they are certainly not desirable species. Some of them may turn out to be serious problems and there is always a chance that they could be introduced to an island ecosystem where they could do serious harm. It would be best to keep them off islands where they do not occur.
Species listed in Appendix 2, Table 5, even though native to American Samoa, exhibit characteristics of invasive behavior and should not be introduced where they are not present.
A number of species used in forestry and ornamental plantings are, at least to some degree, invasive. While many of these species have desirable ornamental or physical characteristics, planting exotics as opposed to native species is a policy question that needs to be carefully considered. Most species that naturalize to any extent will gradually spread throughout available and suitable habitat, given enough time.
Intact native forests are the most resistant to invasion. Any measures that limit the amount of disturbance will help keep invasive species out.
A risk-rating scheme should be developed and the various known and potential invasive species evaluated for their risk of introduction, spread and potential damage. This should be done on a Pacific-wide basis.
A joint training session/workshop should be conducted for foresters, land managers, extension agents, quarantine officers and other interested individuals and organizations in the recognition, exclusion, eradication, and control of invasive species. The goal of the training and workshop should be to foster cooperation and joint action against invasive species.
The purpose of this survey was to give an overall assessment of the situation. Individual species of concern should be more fully evaluated as to extent, invasiveness, and the possibility for control or eradication. Technical assistance should be requested, if needed, to evaluate individual species.
A cultivated Ligustrum sp. was noted. Privets are notorious weed species on tropical islands. If at all possible, this species should be eradicated and Ligustrum spp. banned from further importation.
The Panama rubber tree (Castilla elastica), while spreading, is presently limited in extent. It is a problem species in Hawaii and French Polynesia and is capable of invading intact forests. Given that it in the initial stages of invasion in American Samoa, it would be desirable to evaluate this species for possible control or eradication.
There is a localized infestation of Solanum torvum across from the high school in Leone. This species is spread by birds and is a pest in French Polynesia and elsewhere. It should be eradicated as soon as practical.
A infestation of Ipomoea alba is spreading along the road near the golf course. This species is a weed in Hawaii. Given the local nature of the infestation, this would be a good candidate for eradication.
Desmodium nicaraguense (D. rensonii)
Probably because of their isolation, these islands have fewer weed species than Tutuila. For example, Mimosa diplotrichais apparently not present on Tau. While inter-island quarantine inspection is probably not realistic, some measures could be instituted to reduce the risk of introduction or establishment of weed species not already present. These include cleaning road construction equipment before it is moved between Tutuila (or other locations) and these islands, public education and reporting of problem species, scouting expeditions to discover incipient infestations, and prompt eradication of new infestations.
Recommendations for the individual islands follow.
Tau:
The island also appears to be free of Mimosa pudica infestations. It has been reported as present, but was not seen by us or by Whistler (1992) in his botanical inventory for the National Park of American Samoa. If it is not present, it may be desirable to develop a strategy to prevent its introduction and to eradicate it if (more likely, when) it is found.
Some cultivated species include Clerodendrum quadriloculare, C. chinense, Acacia auriculiformis, Tecoma stans, Lantana camara and Syngonium spp. If it is not feasible to eliminate these species from cultivation, they should be closely monitored for naturalization and spread, as they are all known invasives.
A species of Hedychium (ginger) was seen inland from Tau village. Several Hedychium species are bad forest invaders in Hawaii. Since this is a small infestation in a rural area, it should be eradicated before it spreads further.
Appendix 1 References
Appendix 2 Species by category
Appendix 3 Invasive and potentially invasive species present on Tutuila
Appendix 4 Invasive and potentially invasive species present on Ofu
Appendix 5 Invasive and potentially invasive species present on Olosega
Appendix 6 Invasive and potentially invasive species present on Tau
(1) Former Director, Pacific Southwest Research Station, USDA Forest Service (now retired) and Curator of the Herbarium, National Tropical Botanical Garden, respectively.
(2) Space, James C. and Marjorie Falanruw (1999). Observations on invasive plant species in Micronesia. Report prepared for the meeting of the Pacific Islands Committee, Council of Western State Foresters, Majuro, Republic of the Marshall Islands, February 22-26, 1999.
(3) We would like to thank Colin Steele, Acting Forestry Program Manager, and Manu Tuiono'ula, Forest Health Coordinator, American Samoa Community College Land Grant, for their generous assistance in the conduct of the survey. We would also like to thank Pa'u Young for his assistance in our survey of Tau.
Need more info? Have questions? Comments? Information to contribute? Contact PIER!
This page updated 11 March 2000.