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Special Ecological Areas …
20 years of Alien Plant
Management at Hawai‘i
Volcanoes
Hawaii Volcanoes National Park
Rhonda Loh and Tim Tunison
Hawaii Volcanoes National Park
Kahuku(116,000 ac)
Park Ecosystems…Coastal Strand
Lama Forest
Dry ‘Ōhi‘a Scrubland
Park’s Ecosystems…Pioneer communities
…Montane Shrubland
…Rain Forest
Photos © Thomas Belfield
Rare species,,,
The park provides habitat for over 50 federally listed threatened, endangered and candidate endangered species
‘Akepa
Hau kuahiwi
Nēnē
Mauna LoaSilversword
History of Natural Resources Management…
Feral Ungulates in the Park
Feral Ungulate Management in Hawai‘i Volcanoes NP, 2007
Fence – 110 miles
Managed for all ungulates (~45,000 ac)
Managed for goats, cattle mouflon (133,000 ac)
Park boundary
Kahuku(116,000 ac)
Kīlauea
Mauna LoaStrip
‘Ōla‘a Tract
Koa Forest Recovery on Mauna Loa Strip, 2003
Boundary Fence
Boundary Fence
19781975
Vegetation recovery following fencing and animal removalin rain forest (Katahira 1980)
Alien Plants at HAVO
Kahili ginger replaces native understory and prevents native trees from establishing
Strawberry Guava (Psidium cattleianum) along Highway 11, Hawai‘i Island
Faya tree increases Nitrogen inputs on young volcanic soils
Alien Grasses increase fire size and frequency
Total Acres Burned (ac)
0
4000
8000
12000
16000
1922-1931 1932-1941 1942-1951 1952-1961 1962-1971 1972-1981 1982-1991 1992-2001 2002-2004
Alien Plant Management Strategies (NPS 1986)
# of plantsor
area of infestation
Time
Eradication(Maximumcost-benefit)
Exclusion(exclude from valued areas)
No control(rehabilitation/
alternative restoration
Containment(prevent spread)
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Fountain Grass Distribution at Hawai‘i Volcanoes
30 kilometers
Small Populations (treatment area = 178.4 ac)
Core Populations (treatment area = 1000.4 ac)
Helicopter/vehicle/foot survey & control (106,210 ac)
N
PACIFIC OCEAN
#
Kilauea
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Fountain Grass Control in Hawai’i Volcanoes National Park
Number of individuals removed
Parkwide controlControl of satellite populations
1996-20051993-1995
02000400060008000
1000012000
1985
1987
1989
1991
1993
1995
1997
1999
2001
2003
2005
2007
Fiscal Year
Indi
vidua
ls
Satellite Populations
Parkwide Control
Range Reduction
- Representativeness and/or rarity of vegetation
- Manageability/Vegetation Intactness
- Research and interpretive values
- Plant species diversity/richness/presence of rare species
- Incremental approach. Can be expanded & new ones added as resources become available
SPECIAL ECOLOGICAL AREA’S (SEA)REMOVE DISRUPTIVE WEEDS FROM HIGH PRIORITY AREAS
Systematic ground and/or aerial sweeps
Treatment of all target species within the area(11 spp in 1984)
Revisit sites at 1-4 year intervals
Special Ecological Areas 1985-2007
10 miles
Fences
1985-19891990-20002001-present
How effective is removing target weeds from SEA’s?
What is the cost of managing weeds over time ?
Seasonal Dry ‘Ōhi‘a Woodlands
SEA’s
(18,058* ac)
*includes 10,488 ac helicopter swept
0
0.5
1
1.5
0 5 10 15 20 25
Puaulu Buffer Ainahou Hilina Pali Kahalii Keam oku
01020304050
0 5 10 15 20 25
Puaulu Buffer Ainahou Hilina Pali Kahalii Keam oku
Treated Individuals/AcreIn
divi
dual
s/A
cre
Years Following Initial Treatment
Wor
ker D
aysA
cre
Worker Days/Acre
<0.2 worker day/acre or$40/acre every 2-4 yrs
1-10 individuals/ac
Keamoku Block A&B (2975ac)Worker Days/Acre
0
50
100
150
200
1985
1987
1989
1991
1993
1995
1997
1999
2001
2003
2005
2007
Year
Worke
r Day
s/Acre
Increased use of Helicopter search and aerial treatment reduces workloads
~$1/acevery 2-4 years
Keamoku SEA
Worker Days/Acre
Rain Forest Units 2,491 ac
0
200
400
600
800
0 2 4 6 8 10 12 14 16 18
Treated Individuals/Acre
Thurston (n=13) Small Tract (n=5) Koa Unit (n=7)In
divi
dual
s/A
cre
Years Following Initial Treatment
012345
0 2 4 6 8 10 12 14 16 18Wor
ker D
aysA
cre Worker Days/Acre
$156/ac every 2-4 yrs
~100 individuals/acre
$760/ac every 2 yrs
~600 individuals/acre
Monitoring transects?
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Distribution of Himalayan raspberry in `Ola`a Rainforest SEA
#
#
#
<1%1-5%5-25%
% Cover
500 m
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#
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Distribution of Kahili Ginger
<1%1-5%5-25%
% Cover
500 m
#
#
#
Mesic Forest Units - 458 ac
0
10
20
30
40
50
1985 1990 1997Year
Freq
uenc
y
Kahili ginger Nasturtium Strawberry guava Jerusalum cherry
Number of weeds along transects in Kipuka Puaulu SEA
0500
100015002000
020000400006000080000
Acr
es
Worker Days
Acres Under ManagementGround Partial Ground + Helicopter
Fiscal Year
Wor
ker D
ays
Special Ecological Areas 1985-2007
12,578 ac
66,039 ac
730 1,149
1985 20051990 1995 2000
1985 20051990 1995 2000
0.00
0.02
0.04
0.06$11.62/ac $3.40/ac
Wor
ker D
ay/A
c
Worker Day $ Cost/Acre
Fiscal Year
Special Ecological Areas 1985-2007
Ground + Helicopter Sweeps
1985 20051990 1995 2000
0
5000
10000
15000
0.0
0.1
0.2
0.3$58/ac $22/ac
Worker Days $ Cost/Acre
Acres
Acr
es
Wor
ker D
ay/A
cGround Swept SEAS 1985-2007
Fiscal Year
2,089 ac
10,535 ac
1985 20051990 1995 2000
Conclusions:
1) Populations of alien plant species can be reduced and maintained at very low levels after several cycles of control work
2) Subsequent recruitment of alien plants from the soil seed bank and seed rain from nearby areas
4) Workloads drop significantly after initial control efforts
3) Continued follow-up treatments are required in all areas and may be needed indefinitely
Future Directions Addition and Expansion of new SEAs
Optimize treatment intervals
Improve technologies – imagery and analysis, control methods, biocontrol
Increase community participation
Reduce seed rain/recruitment- expand units and establish buffer areas
Reclaim/restore adjacent degraded areas
Partnerships with adjacent landowners
Acknowledgements- Chris Zimmer, Mike Gates, Julie Leialoha, Alison Ainsworth, Bobby Mattos, Jon Makaike, David Benitez, Linda Pratt, Chuck Stone, Resources Management Staff, Pacific Island Exotic Plant Management Team, Cooperative Ecosystem Studies Unit- Research Corporation of University of Hawai‘i, Big Island Invasive Species Committee, Three Mountain Alliance, Hawai‘i Forest and Trails, Friends of Hawai‘i Volcanoes, Forest TEAM Program, Youth Conservation Corp, Alu Like.
MAHALO!