1. Implementing an Early Detection Program on O`ahu Island: Prioritizing for Weed Control
Danielle Frohlich, Alex Lau, and Clyde Imada, Bishop Museum
Abstract:
Historically, the Invasive Species Committees (ISCs) have lacked a comprehensive early detection program for ensuring the greatest possibility of identifying potential new invaders. In response to this ongoing issue, the O‘ahu Early Detection (OED) program was initiated during the summer of 2006.
The OED project comprises two stages: stage one consisted of surveys of plant importation “hot spots,” including nurseries, botanical gardens, and community gardens; stage two consists of roadside surveys to determine target species distributions and candidacy for rapid-response control efforts. Subsequent to “hot spot” surveys, a system was developed for determining species candidacy for rapid response and control if noted during a roadside survey, a scheme based upon a system developed by the New Zealand Department of Conservation. This “weed-led” system aims to discover and control weedy species at an early stage of establishment, drawing upon documented knowledge taken from the Hawai‘i Weed Risk Assessment and distribution information gleaned from the Bishop Museum Herbarium Pacificum collection. This system is an essential scientific tool which the ISCs can use to prioritize target species selection.
Acknowledgements
OED wishes to thank Ryan Smith, Dr. George Staples, Forest and Kim Starr, and Dr. Shahin Ansari for their assistance and support.
References
Daehler, C.C. and J.S. Denslow. Weed Risk Assessments for Hawaii and Pacific Islands.
Timmins, S. and S. Owen Eradicate this weed or not? Decision-making for weed-led control programmes. Science Poster no.21 Department of Conservation, Wellington, New Zealand.
Piper aduncum, a pioneer species that produces copious bird-dispersed seeds, received a score of 18 on the WRA, and an ‘Effect on System’ score of 8. Since there are only 2 known populations of this species on Oahu, it receives a Priority Ranking Score of A8.
Topobea parasitica, a gap-invading vine with a WRA score of 2 and an ‘Effect on System’ score of 7. Since there are only 2 known individuals of this plant on Oahu, this plant receives a Priority Ranking Score of C9, and is a high priority for removal by the Oahu Invasive Species Committee.
Performed by Dr. Shahin Ansari (Lyon Arboretum) working with Dr. Curt Daehler (UH Manoa)
49 questions related to:
Degree/extent of cultivation
Climate and distribution
Weed elsewhere?
Undesirable traits (i.e. Thorns, toxicity to animals)
Type of plant (i.e. Aquatic, grass, N-fixing)
Reproduction (hybridization, self-compatible)
Dispersal mechanism (water, wind, bird)
Persistence attributes (prolific seed production, seed bank)
Species we evaluate will generally score between 0 and 29 on the WRA.
See for more info
Step 1: Initial Assessment of the Plant Species
Step 2: Perform Weed Risk Assessment (WRA)
Step 3: Calculate the ‘Effect on System’ Score No
“Safe” List:
(leave to homeowners, nursery owners to monitor, report)
Weed?
Weed effects on composition and structure of native community (0-3)
Weed suppresses native regeneration (0-3)
Yes ?
Well-distributed?
(Cult. or Nat.)
Well-distributed?
(Cult. or Nat.)
Effect on System
(0-9)
Yes No No
Yes
Recommend against cultivation
Potential Target (get Weed Risk Assessment, ask experts)
Watch list
Weed effects on agriculture (0-3)
Step 4: Calculate the species’ ‘Weediness Score’ and ‘Weediness Group’
Step 5: Assess the 'Practicality of Control'
Step 6: Derive a ‘Priority Ranking’
Priority Ranking Score
Action to take:
Kill population immediately
High priority for control, assess for immediacy
Control possibly performed- reevaluate after further surveys
Consider continuing to map, document distribution
Out of scope of project
A10
Initial control cheap, achieve in less than one day, little or no monitoring necessary = 10
Initial control cheap, achieve in 2-6 days, little/no monitoring needed = 9
Initial control will take over a week, little/no monitoring needed = 8
Initial control will take over a week, moderate monitoring investment= 7
Initial control will take over a week, monitoring will be intensive = 6
Species appears to be widespread, based on roadside surveys = 5
Weediness Score = Score on WRA (0-29) + “Effect on System” (0-9) score
Weediness Group:
A= 26 and up
B= 17-25
C= 7-16
D= 6 and below
A7-9, B8-10, C9-10
A6, B6-7, C7-8, D9-10
A5, B5, C6, D6-8
C5, D5