PDF《Invasive plant species on Kosrae,》

Invasive plant species on Kosrae, Federated States of Micronesia James C Space, Barbara Waterhouse, Julie S.

Denslow, Duane Nelson and Erick E. Waguk U.S.D.A. Forest Service Pacific Southwest Research Station Institute of Pacific Islands Forestry Honolulu, Hawai'

i, USA

22 December

2000 1

22 December

2000 Invasive plant species on Kosrae, Federated States of Micronesia James C Space, Barbara Waterhouse, Julie S. Denslow, Duane Nelson and Erick E. Waguk1 This is a continuation of the survey of islands in Micronesia for invasive plant species requested by the Pacific Islands Committee, Council of Western State Foresters. A survey of other Micronesian islands was conducted in

1998 and was discussed in a previous report2 . This report is based on a survey of the island of Kosrae, Federated States of Micronesia, from

24 to

28 March 2000. The objectives, as with the previous survey, 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 Kosrae, could be a threat there. During our visit local experts showed us sites of known infestations. We also had available copies of various botanical and weed surveys conducted in the past (see Appendix 1, References). A visit of such short duration does not permit an exhaustive survey of the weed flora of the island. However, the intent was to conduct an overall survey. Additional surveys of

1 Former Director, Pacific Southwest Research Station, USDA Forest Service (now retired);

Botanist, Australian Quarantine and Inspection Service;

Research Ecologist/Team Leader, Institute of Pacific Islands Forestry, USDA Forest Service;

Forest Health Coordinator, Institute of Pacific Islands Forestry, USDA Forest Service and State Forester, Kosrae State, Federated States of Micronesia, 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.

2 individual species or sensitive areas 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 Kosrae have been grouped into four 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 on Kosrae (352 species). 2. Species that are invasive elsewhere and are also invasive or potentially invasive on Kosrae (12 species). 3. Species that are invasive or weedy elsewhere and are cultivated, common or weedy on Kosrae (48 species). 4. Native species (or early introductions) that exhibit aggressive behavior (9 species). These species are listed in Appendix 2. Additional information about each species is located on a World Wide Web site, http://www.hear.org/pier, and on the PIER-CD. There are a number of other species that are invasive weeds in gardens, fields, and pastures and along roadsides but don'

t seem to pose a particular threat to wildland ecosystems. These species are not included. 1. Dangerous species not known to be on Kosrae Perhaps because of its location off the beaten path , many invasive species have yet to reach Kosrae. These are listed in Appendix 2, Table 1. The worst of these include the following: Antigonon leptopus (chain of hearts). This climbing vine has become a widespread pest on Guam and there are isolated plants in cultivation on Pohnpei. Traffic between Guam, Pohnpei and Kosrae and the fact that this is a pretty flower that people like to plant in their gardens makes this species a potential threat to Kosrae. Cecropia obtusifolia and C. peltata, invasive tree species that are a problem in Hawai'