Forested Wetlands Team
Institute of Pacific Islands Forestry
Hilo, HI
Impacts of Climate Change on the Ecosystem Services of
Micronesian Mangrove Forests
Japan
Hawaii
CNMI
Philippines
Guam
Yap
Palau
Chuuk
Pohnpei
Marshall
Islands
Kosrae
Fiji
New
Caledonia
American
Samoa
Tahiti
Kosrae
1 km
Annual Net Primary Production
Forest Type
NPP (t C ha-1 yr-1)
Temperate Forests1
4.3 – 20.6
Tropical Rain Forests2
6.5 – 16.0
Tropical Savannas and
Grasslands3
Mangrove Forests4
4.1 – 17.9
5.7 – 24.4
1
Grace et al. 2001
Reich and Bolstad 2001
3
House and Hall 2001
4
Mitsch and Gosselink 1993
2
Economic Value of mangrove forests
in Kosrae FSM: $1,000,000/yr
(Naylor and Drew 1998)
Firewood $270K
Mangrove Crab
$550K
Fish $170K
Many fish
species
swim
ofinto
fishmangrove
migrate into
forests
mangrove
from adjacent
forests from
coral reefs
adjacent
coral
andreefs
seagrass
and seagrass
beds
beds
• Dense mangrove roots protect small,
young fish from being eaten by larger
fish
Great Barrier Reef Marine Park Authority (1996)
Center for Coastal Fisheries and Habitat Research (2005)
Mangrove forests in Micronesia also provide habitat for
unique assemblages of terrestrial fauna
www.softbills.com
Photo: P. Colin
Riverine mangrove forests can protect coral reef ecosystems by significantly reducing the
amount of sediment load entering the system.
“…ecological systems of small islands and the functions that they perform, will be
sensitive to the rate and magnitude of climate change and sea level raise, especially
where exacerbated by human activities.” (IPCC, 2007)
How will sea level raise impact organic matter dynamics in mangrove ecosystems?
Low Zone
Intermediate
Zone
High Zone
High Zone
Intermediate Zone
Low Zone
IMPACTS OF INCREASED FLOODING
ON LEAF RESIDENCE TIME
IMPACTS OF INCREASED FLOODING
IN LEAF RESIDENCE TIME
120
Low Zone
Intermediate Zone
High Zone
Percent Remaining
100
80
60
40
20
0
July
August
2007
Distance traveleled (cm/24 hours)
1400
Low Zone
Inter. Zone
High Zone
1200
1000
800
P < 0.05
600
ns
400
200
0
July
August
2007
IMPACTS OF INCREASED FLOODING
ON CRAB FEEDING
DAY 0
DAY 2
Photographed leaves on day 0, 1, and 2. Loss rate was
determined from change in surface area of leaf using ImageJ
photoanalysis package.
110
Percent Remaining
100
90
80
70
60
50
High Zone
Intermediate Zone
Low Zone
40
30
8/13
P < 0.05
8/14
8/15
2007
8/16
8/17
Mass loss from leaf litter bags
in the mangrove
Normal
Highhydrology
Zone
100
* *
80
Leaf mass loss (%)
Flooded
Low
Zone
60
40
*
20
>
0
C
N
P
NP
C
N
P
NP
IMPACTS OF INCREASED NUTRIENT LOADING AND SEA LEVEL
ON MICROBIAL RESPIRATION IN MANGROVE SEDIMENTS
4 x 3 factorial design:
High zone (C, P, N, NP)
Intermediate Zone (C, P, N, NP)
Low Zone (C, P, N, NP)
CO2 flux was measured from each core at the end of the 8 week experiment during
slack low tide using a LICOR-6400.
Soil CO2 efflux from the
mangrove
2 months
CO2 efflux (uMoles / m2 /s)
Normal
Highhydrology
Zone
Flooded
Low
Zone
*
1.2
1.0
0.8
*
0.6
0.4
>
0.2
0.0
C
N
P NP
C
N
P NP
Conclusions
1. A 20 – 40 cm increase in sea level has the potential to significantly
impact organic matter (and nutrient) cycling in mangrove forests through decreased
residence time of organic matter, activity of detritivores, decomposition of leaf litter,
and microbial respiration (or decreased root productivity).
2. Changes in the above process can influence important biogeochemical functions of
mangrove forests (e.g., food webs, atmospheric C sinks)
3. Nutrient additions increased decomposition of leaf litter (N, NP) as well as
respiration (NP) in sediments. If CO2 efflux is accurately reflecting trends in
decomposition processes in sediments, mangroves forests are at risk of keeping
up with sea level rise with increased nutrients.
Above and Belowground Biomass
Forest Type
AGB (t C ha-1)
BGB (t C ha-1)
Tropical Rain Forests1
76 - 247
35 – 50
Tropical Grasslands and
Savannas2
Mangrove Forests3
6.7 – 169.1
20 - 30
71-590
2.6 – 231.14
Micronesian mangroves
3243
2.0 – 13.44
1
Grace et al. 2001
House and Hall 2001
3
Kauffman unpub. data
4
Cormier 2003
2
Distribution of mangrove species in the Indo Pacific region
Indo West Pacific (IWP)
20
5
0
30
10
20
P A C I F I C OC E A N
5
Pohnpei
30
Palau
10
Kosrae
EQUATOR
10
I N D I AN O C E A N
5
40
30
20
30
20
CORAL
SEA
0
10
5
Moreton
World spp ~70 total, 58 IWP & 12 AEP
NB: Curved lines represent species number boundaries
0
NC Duke et al. 1998
Tree species richness w/in mangrove forests in Micronesia ranges from 19-11
Rhizophora spp.
Bruguiera gymnorrhiza
Sonneratia alba