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Discussion Paper presented at the DIKTI-International Summit Jakarta 16-19 December 2010.

VULNERABILITY OF MANGROVES IN INDONESIA TO CLIMATE CHANGE: a view

from a mangrove ecologist

Prof. Dr. Sukristijono Sukardjo, D.Sc

The Center for Oceanography, Indonesian Institute of Sciences, Jakarta, Indonesia. E-mail:

s_sukardjo@yahoo.com

ABSTRACT

Brief review of existing data and reports concern with Indonesian coastal resources related to

climate change are presented. Not all of the climate change factors will be discussed and only

sea-level rise may exert a dramatic influence on mangroves. With deal in mind that the 1 m sea-

level raise will absolutely affect the mangroves, the government of Indonesia consider trends and

salient characteristics of mangrove ecosystems that over best clues as to how mangroves may

respond threats in future, followed by an assessment of present threats and impacts that are most

likely to continue or intensify into the future. Mangroves can demonstrate persistence at

timescales over which morphological evolution of shoreline occur. Thus, it is logical to assume

that mangroves would continue to respond as they have over the past century.

INTRODUCTION

One of the most distinctive features of Indonesia is its sheer physical size; stretching over

5,700 km from Sumatra in the west to the border with Papua New Guinea (PNG) in the east.

Indonesia, with land and marine territory of about 7.7 million km2 consisting of some 17,504

islands and approximately 95,181-108,000 km of coastline (MOMAF 2007a, ANON. 2003), is

forth only to Canada, USA and Russia in the length of its coastline (WORLD RESOURCE

INSTITUTE 2001 cited MOMAF 2007). However, considering economic utilization, biological

diversity and ecological importance of the coastal zone and its extent, Indonesia certainly ranks

first among all nations of the world. These coastal areas form an important and valuable natural

resource with high potential economic value, and a potentially important production area for

food, and are one of the most bio-geochemically active zones of the biosphere, representing a

potentially important sink or source of carbon.

Throughout the Indonesian archipelago, coastal resources have been used by local

communities for millennia. Pressures upon them are great to their high biological diversity and

productivity (BAPPENAS 2003). These coastal resources are in high demand e.g. in the post-

tsunami period, the demand of mangrove forests for mitigation of tsunami impacts are worldwide

(Mazda et al. 2007, Forbes & Broadhead 2007, Alongi 2008). Approximately 65% or more of

Indonesia’s population, estimated to total at least 276 million by the year 2020 (BPS 2004), live

adjacent or very near to the coastal zone, increasing the complexities for resource management

and the likelihood of coastal degradation (Sukardjo 1999, 2002). There are 8,090 coastal villages

in Indonesia with 3.91 millions households, and totaling of 16.42 millions peoples. Of which the

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majority of people (32%, 5.254 millions) within Indonesia’s coastal zones live in poverty

(MOMAF 2007).

In many ways, coastal zones of Indonesia typify the problems (Mimura 2006) and policy

challenges presented by the processes of Global Environmental Change (GEC), Global Climate

Change (GCC) and systematic development of the coastal areas themselves in Indonesia (cf.

UNEP 2005, UNEP-WCMC 2006). These zones are under increasing environmental (resource

exploitation/over-exploitation) pressure and are exhibiting unacceptable environmental changes

as a consequence of population growth, urbanization, tourism and other multiple and often

conflicting resource usage trends. Mitigation of the resource conflict and the practical adaptation

of the sustainable economic development policy objective require innovative policy responses

e.g., replanting the mangroves along Indonesia’s coasts (Sukardjo 2005).

In the aftermath of the Great Sumatra earthquake and the tsunami, Indonesia has

undertaken various investigations (See also Kathiresan & Rajendran 2005, Serigstad & Muchtar

2006, Forbes & Broadhead 2007, Iverson & Prasad 2007, UNEP 2005, UNEP-WCMC 2006),

and recently the devastating along the Mentawai Islands caused by tsunami, has focused GOI

attention on the role of natural barriers, such as mangroves, coral reefs and sand dunes, in

protecting vulnerable coastlines and populations from destructive storm events. Indonesia has

announced plans for widespread replanting of degraded and deforested mangrove areas as a

means of bolstering coastal protection (Sukardjo 2005). In order to make use of the coastal zones

in a sustainable way, Indonesian ministries (MOF, MOMAF, MOHA, and SMOE as lead

agencies) and institutions (e.g., LIPI, BAKOSURTANAL etc. as back stopping offices) are

taking much interest.

Mangrove forests are the dominant ecosystem along Indonesian coastlines and are

important interface in the exchange of sediment, organic materials and gases between land,

atmosphere and ocean, and represent valuable resources for human being (Sukardjo 2009a).

Also, mangrove ecosystems in the country are open systems, which exchange and energy with

the adjacent marine and terrestrial ecosystems. However, they are found to differ in their energy

signature or the sum of all forces which dictates the types of organisms that will survive and the

speed of ecological processes (Alongi 2009). Cintron and Schaeffer-Novelli (1984) have shown

that the magnitude and periodicities of forcing functions such as tides, hydro-period and stresses

such as cyclones, drought, salt accumulation and frost may largely determine the energy

signature of a mangrove stand and therefore the floristic and faunistic composition as well as the

community structure. Mangrove forests especially those that are located within estuarine

lagoons, are complex and dynamic, with strong gradients in chemical composition of water

induced partly by hydrodynamics processes and biological productivity.

At the ecosystem level, mangrove trees dominate carbon and nitrogen flow, being among

the most productive plants in the ocean (Alongi 2002). Despite this high productivity, most labile

carbon fixed by the trees appears to be retained within the ecosystem (Twilley 1988). Nitrogen

also appears to be efficiently assimilated and retained, due possible to the evolution of various

conservation mechanisms. At the forest level, trees and microbial consortia constitute a tight

energetic link in concert with crabs that as keystone species, intensively bioturbate sediments

fostering microbial growth and soil conditions beneficial to tree growth (Kristensen et al. 1995,

Alongi et al. 2002).

Global climate has large natural variability at all time and space scales. It is known also

that global warming can be caused by green-house gases. Climate change will have enormous

influences on the intertidal wetland along the Indonesia’s coasts. Increases in atmospheric carbon

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dioxide (CO2) concentrations and associated increases in air and sea temperatures, rising sea-

level, changes in oceanic circulation, rainfall patterns and frequency and intensity of storms are

highly likely to affect the physiology, ecology and ultimately the stability of coastal wetland

habitats (Table 1). The intertidal position of Indonesia’s mangroves makes them particularly

vulnerable to changes in sea-level, although other climate change factors will also exert a strong

influence on coastal wetland communities (Table 1). Past climate change has occurred with

limited human modification of the coast compared to current level s of development in

Indonesia. Human activities have resulted in loss of mangroves and other coastal wetlands,

disruption to connectivity, enhanced availability of nutrients, changed sediments dynamics and

the creation of structures that will prevent landward migration of wetlands with sea-level rise

(e.g., roads, beams, bunds and sea walls). Many of these human impacts will reduce the

resilience of intertidal wetlands to climate change.

A factor important to mangrove ecosystems is the extent of sea-level rise that might

accompany an increase in mean global temperature. My paper examines the possible effects of 1

m sea level rise on the coasts of Indonesia during the coming century and the probable socio-

economic and policy responses and will focus on vulnerability of mangroves in Indonesia that

will be possible applicable for the sustainable mangroves management e.g., Sukardjo et al.

(2010), Sukardjo and Alongi (2011).

INDONESIAN MANGROVES AND CLIMATE CHANGE

General effects of a sea level rise

There is evidence that carbon dioxide and other greenhouse gases resulting from

industrial and agricultural activities have been accumulating in the Earth’s atmosphere in recent

decades, and that these will lead to an increase of 1.50o to 4.50

oC in mean atmospheric

temperature. Such an increase would result in an expansion of the volume of near-surface ocean

water (the steric effect), and the partial melting of snowfields, ice sheets and glaciers, releasing

water to augment the oceans. The predicted outcome is a world-wide sea level rise (Barth &

Titus 1984). For example, studies by Barth & Titus (1984) have indicated the possibility that

human-induced global climate changes will result in a rise of sea level: it is thought that

atmospheric warming will lead to a reduction in glaciers and ice sheets and a consequent

addition of water volume to the oceans, as well as to thermal expansion of ocean waters.

Hoffman (1984) estimated a rise of 0.24-1.17 m (0.78-3.83 ft) by 2050, and 0.56-3.45 m (1.83-

2.83 ft) nu 2100. According to these predictions, sea level will stand 1 m (3.3 ft) higher than it is

now between 2045 (high scenario) and 2140 (conservative scenario). A global sea level rise of 1

m will greatly modify coastal environments, producing erosion and submergence, especially on

low-lying sectors (Titus 1986, Bird 1986, 1988) (Table 2). Such a rise will enable the highest

tides to reach levels of at least 1 m above the present limits, allowing for a possible increase in

tide range as near-shore waters deepen. On most coastlines the high tide line will move landward

to well beyond the 1 m contour because of initiation or intensification of erosion. The extent of

erosion will depend on how the near-shore sea floor is modified by erosion or accretion as it

migrates landward, and associated changes in the wave energy regime. The low tide line will

also move landward, at least part of the existing intertidal area becoming permanently

submerged.

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The coasts of Indonesia (beach and sandy coasts, steep and cliffed coasts, estuarine and

lagoons, delta and coastal plains)

The coastline of the 17,504 islands which make up Indonesia has a total length of about

95,181-108,000 km. Where the mountainous interior reaches the sea there are steep and cliffed

coasts, and many of the islands are also high and steep-sided. Volcanoes and volcanic activity

have influenced coastal features, the most obvious example being Krakatoa, the volcanic islands

in Sunda Strait which are a legacy of an explosive eruption in 1883.

Generally steep coasts have forest vegetation on rock formations that have been deeply

weathered, but there are cliffs and shore platforms on sectors exposed to strong wave action.

There are extensive river deltas, some of which have combined to form an alluvial coastal plain,

as in northern Java.

Beaches are extensive on the more exposed coastlines, especially in south-west Sumatra,

southern Java, and the eastern islands: often they are backed by beach ridges, sometimes with

coastal dunes, as at Parangtritis in Java. Sandy beaches have received sediment from rivers, cliff

erosion, coral reef erosion, and volcanic outfall. Where they include calcareous sand they have

locally been cemented to form beach rock. In some places they are backed by multiple beach

ridges, which represent intermittent progradation by accretion of sand carried alongshore or in

from the sea floor. These impede stream outlets, and may enclose lagoons and swamps, as on the

south coast of Java east of Cilacap.

Headlands usually have steep slopes mantled with weathered material, held in place by a

scrub and forest cover. On low wave energy coastlines within the Indonesian archipelago

actively receding cliffs are rare (Bird 1981), but occasionally there is slumping of the weathered

mantle, especially after the slope foot has been undercut by storm waves. Active cliffing is seen

on the more exposed southern coast of Sumatra, Java and the islands to the east (Lombok,

Sumba, Sumbawa).

The larger rivers in Indonesia have high water and sediment yields to the sea, and only

their lower reaches are estuarine. Many Indonesian deltas are still growing relatively quickly,

with shorelines prograding up to 120 m/year. Progradation has been aided in Java by increased

fluvial sediment yields following the clearance of forests in the hinterland. However, several of

these deltas show sectors of erosion, especially where the river mouth has been diverted naturally

or by canal cutting.

There are fringing coral reefs on headlands and islands where the shores are not occupied

by mangroves and mudflats, and outlying patch reefs (often surmounted by sandy islands) are

numerous within the Indonesian archipelago.

Wave action is generally weak within the Indonesian archipelago, but is stronger on

coasts exposed to ocean swell from the Indian Ocean to the south-west and the Philippines Sea to

the north-east, and on coasts exposed to south-easterly and north-easterly trade winds. Tropical

cyclones do not occur in Indonesia, but swell transmitted from them occasionally washes the

south coast of Java.

Tides are generally small (<2m), but increase to >6m on the south coast of Irian Jaya.

Tsunamis are generated by earthquakes or volcanic eruptions: in 1883 the Krakatoa explosion

produced waves up to 30m high on tee west coast of Java.

Mangrove coasts in Indonesia

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Most of today’s mangroves rests upon the remains of their past – a reflection of the ebb

and flow of Earth’s history. The current position of Indonesia’s mangrove forests is a legacy of

the Holocene (Yulianto et al. 2004, 2005). Mangroves grow luxuriantly on low-lying sectors of

the coasts of Indonesia which are not exposed to strong wave action (Sukardjo 1980). Also,

mangroves occupying low-relief islands and/or carbonate settings, where rates of sediment

supply and available upland space are ordinarily low, such as on small islands of Natuna Sea,

Maluku and Nusa Tenggara, are typical small island mangrove assemblage.

Mangroves thrive in a tidal environment where adaptation to change in sea-level over

long timescales is the rule rather than the exception. The ability of mangroves to successfully

adapt to change in sea-level, as already noted, depends on accretion rate relative to rate of sea-

level change. Rise of mean sea-level (MSL) has an immediate and direct effect on ecosystems of

the intertidal zone, with decline in influence of terrestrial processes at all locations, and increase

in influence of marine processes. It has been envisaged that species with specific tolerances

within the tidal spectrum will migrate landward (Hekstra 1989) as their former habitats become

increasingly marine.

The conventional wisdom concerning Indonesian mangroves and global climate change

focuses almost exclusively on sea level rise as the most critical factor. Interpolation from the

results of Clark and Primus (1987) for Indonesia as major areas of mangrove in the world

(Spalding et al. 2010) again show coherent rises averaging 110 cm, or 89 cm/100 years. The

predicted possible rates of greenhouse-induced sea-level rise of 100-200 cm/100 years make it

inevitable that most Indonesian mangroves will collapse as viable coastal ecosystems. Accepting

the notion that Indonesian mangroves along macro-tidal (>4m) coastlines, and/or in areas

adjacent to significant river input, are the least vulnerable to the impact of sea-level rise (cf.

Woodroffe 1995, Schaeffer-Novelli et al. 2002, McLeod and Salm 2006), and Sulawesi,

Halmahera, eastern coasts of Sumatra, and West Java are identified as most vulnerable.

However, the environmental diversity of Indonesian mangroves or mangrove forests (cf. Thom

1982, Woodroffe 1987) suggests that various factors in addition to sea-level rise contribute

towards their ability to maintain extent, location and zonal organization during sea-level rise.

Clearly, some Indonesian mangroves will survive and perhaps even thrive with the

predicted changes in climate (Table 1). But it is just as clear that some won’t survive. Given all

of the confounding responses by Indonesian mangroves to increase in humidity, CO2, and sea-

level, the most realistic scenario is to delimit the least and most vulnerable forests, an exercise

that has been done for tropical rainforest (Cramer et al. 2004, Sukardjo 2010).

CONCLUDING REMARKS: my views

The predicted global sea-level rise will cause major problems in coastal areas in

Indonesia, particularly severe in the low-lying areas. For example, rising sea levels due to

climate change and the consequent rising temperature pose a grave threat to mangroves. Large

areas of coastal mangroves in Indonesia could be lost if sea levels continue to rise due to the

expansion of the oceans and melting of polar ice caps. Disruption of established intertidal forests

and relocation on formerly more terrestrial surfaces as these become inundated by the rising sea

may not be so simple, with alteration of ecological and sedimentological processes in different

islands.

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Mangrove populations are not static. For example, knowledge of habitat change in an

area involving changing patterns of sedimentation would clearly strengthen the hand of an

ecologist seeking to study community structure. From a geomorphic point of view, succession is

potentially demonstrable where sedimentary regression has occurred. In terms of the array of

habitats colonized by mangroves it represents one type of habitat change where either continuous

or episodic mud deposition is the dominant process. The mangrove succession of species

continues and the inner part of the mangrove fills with sediment and the water depth decreases.

So the new species can replace the species that grow in the deeper water. This process continues

until either the seaward boundary of the mangroves is damaged by man or by natural force. It

appears that mangrove succession may occur where a steady input of mud facilitates shoreline

progradation. Mangrove may progress landwards at a rate determined by the rate of sea-level

rise, the rate of vertical accretion, and slope and space at the landward edge of each island in

Indonesia. Zonal patterns of plants and animals will be altered slightly and erosion at the seaward

front will increase (UNEP 1994). The ability of mangroves to accommodate future sea-level rise

in Indonesia will likely depend on factors such as tidal range, sediment supply and tree species

composition. These factors are likely to be magnified on islands of both low- and high-relief and

in Nusa Tenggara where rates of sediment supply, available upland space and mangrove growth

rates are usually low (Cf. Ellison & Stoddart 1991, Parkinson et al. 1994, Semeniuk 1994,

Alongi & de Carvalho 2008).

In assessing mangroves response to the scenario of predicted sea-level rise in ensuing

decades we need to consider the sensitivity of the thresholds which govern the transition from

expansive to refuge mode in mangroves, indifferent environmental conditions of coastal district

(Kabupaten) of each island in Indonesia (See also Box 1: Evaluation of physical features of

coasts for replanting mangrove). With 17,504 islands and their location Indonesia posses

diversified environmental settings and tides characters. Consequently, for example, the presumed

rise in sea-level by as much as 12 cm (IPCC 2001) is difficult to evaluate owing to past and

recent variations in local relative sea level (Rull et al. 1999). The effective management of

mangroves in the environmentally sensitive zone due to climate change requires their accurate

and expedient mapping (Scale 1:50,000 and 1:25,000), which is ideally accomplished from

remotely sensed data thanks to the unique characteristics of mangrove stands. Also, in view of

the increasing salinization of coastal zones due to climate change and sea-level rise; there is a

real need to develop salt-tolerant crop varieties that can be grown in the coastal areas.

The economic, political and management implication of the collapse of Indonesian

mangroves due to climate changes (if the prediction of sea-level rise are correct) (Table 1, Boxes

1 and 2) are considerable, not least because traditional methods of coastal protection (such as

construction of sea-walls and similar protection works) are inimical to the ecological

requirements of mangroves. Controls of timber exploitation in Indonesia and other potentially

disruptive uses can, under the circumstances we have described, have only a marginal effect in

offsetting the consequences of rising sea-level. Mangroves occur on most coastlines of

Indonesia, where their significance in the life of human population associated with them, their

function in coastal sediment stabilization, as well as their intrinsic scientific importance as

ecosystems and recorders of biotic diversity, indicates that particular attention be paid to their

survival. It is difficult to generalize about the effect of climate change on mangrove ecosystems

in Indonesia as each system is very much the product of local topographical, climatic and

anthropological influences. Also, the severity of these impacts will vary in relation to regional

differences in climate change (IPCC 2001). It is in the context of Tables 1, 2, 3 and 4, Boxes 1

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and 2; general suggestions can be evaluated by research (for major issues by all GOI agencies

concern with the climate changes) as follow:

1. More information is required on patterns and rates of natural and human change on

the coasts of Indonesia at the present time (at least maps of scale 1:50,000).

2. More information is needed on changes in the relative levels of land and sea on the

coasts of Indonesia (based on maps scale 1:25,000 at Kabupaten level), including the

extent and scale of land subsidence as well as trends in sea-level determined from tide

gauge data.

3. Land-use are required for coastal areas in Indonesia, accompanied by assessments of

the economic returns from such activities as shrimp farming and salt manufacture as

well as fishing.

4. Detailed surveys (maps of 1:25,000) at Kabupaten level are required for each type of

coastline (beaches and beach ridges, steep and cliffed coasts, estuaries and lagoons,

deltas and coastal plains, mangrove coasts and former mangrove coasts) to estimate

the extent and effects of a sea-level rise that is at first gradual, attaining 12 to 18 cm

by the year 2030 and then accelerating to reach 1 m by the year 2090.

5. On the basis of para 4, estimates are needed of the economic losses that will result

from the predicted submergence and erosion by the sea, the number of people

disadvantaged and displaced, and the impacts these socio-economic changes will

have on the immediate hinterland and other areas islands where resettlement may

occur.

6. Also on the basis para 4, an attempt should be made to predict possible alternative

land uses for areas behind submerged and eroded coastal areas.

7. Assessments are required of the preferred pattern and extent of sea wall construction

to prevent coastal submergence and erosion, and the likely costs of such engineering

works.

8. More data is needed on the techniques of moving intertidal and near-shore mud

deposits onshore, or to site off eroding coastlines, as a means of preventing erosion

and submerge, and of maintaining coastal land areas by artificially raising them.

9. Assessments should be made of the possibilities and problems of retaining more fresh

water inland as a means of promoting aquaculture, and of diminishing river flooding

and sea-level rise in Indonesia.

10. Existing policies of land and resource use in coastal areas e.g., the sustainable

mangroves management, should reviewed in terms of the predicted 1m sea-level rise

during the coming century in Indonesia

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Table 1. Predicted effects of climate change factors on mangroves and key references (Source:

Alongi 2008 and 2009): a summary for Indonesia.

Climate change Processes affected Likely impact References

Altered ocean

circulation

patterns

1. Dispersal

2. Gene flow

Change in community structure Duke et al. 1998,

Benzie 1999

Increased air and

sea temperature

1. Respiration

2. Photosynthesis

3. Productivity

Reduced productivity at low latitudes

and increased winter productivity at

high latitudes

Clough and Sim

1989, Cheeseman et

al. 1991, 1997,

Cheeseman 1994

Enhanced CO2 1. Photosynthesis

2. Respiration

Increased productivity, but dependent

on other limiting factors (salinity,

Ball et al. 1997

11

3. Biomass allocation

4. Productivity

humidity, nutrient)

UVB radiation 1. Morphology

2. Photosynthesis

3. Productivity

Few major effects Lovelock et al. 1992,

Day and Neale 2002

Rising sea level 1. Forest cover

2. Productivity

3. Recruitment

Forest loss seaward,

Migration landward, but dependent

on sediment inputs and other factors

(see Table 3) and human

modification to the landscape,

Loss of salt marshes and salt flats

Ellison and Stoddart

1991, Woodroffe

1995, Morris et al.

2002, Semeniuk

1994, Cahoon et al.

2003, Rogers et al.

2005b

Extreme storms 1. Forest growth

2. Recruitment reduced

3. Reduced sediment

retention

4. Subsidence

Reduced forest cover Woodroffe and

Grime 1999, Baldwin

et al. 2001, Cahoon

et al. 2003

Increased wave

and wind

1. Sedimentation

2. Recruitment

Change in forest coverage, depending

on whether coasts are accreting or

eroding (interaction with sediment

stabilization from seagrass loss)

Semeniuk 1994

Reduced rainfall 1. Reduction in

sediment supply

2. Reduced ground

water

3. Salinisation

Loss of surface elevation relative to

sea level,

Mangrove retreat to landward,

Mangrove invasion of salt marsh and

freshwater wetlands,

Reduced photosynthesis,

Reduced productivity,

Species turnover,

Reduced diversity,

Forest losses

Rogers et al. 2005a,

b, Whelan et al.

2005, Smith and

Duke 1987

Reduced

humidity

1. Photosynthesis

2. Productivity

Reduced productivity,

Species turnover,

Loss of diversity

Ball et al. 1997,

Clough and Sim

1989, Cheeseman et

al. 1991, Cheeseman

1994

Enhanced rainfall 1. Increased

sedimentation

2. Enhanced ground

water

3. Less saline habitats

4. Productivity

Maintain elevation relative to sea

level

Maintenance of surface elevation

Increased diversity

Increased productivity

Increased recruitment

Rogers et al. 2005a,

Whelan et al. 2005,

Krauss et al. 2003.

Smith and Duke

1987

Table 2. The general effects of coastal submergence (Source: Bird 1986, 1988, Woodroffe 2002)

that applicable for Indonesia.

1. On cliffed coasts submergence is likely to accelerate coastline recession, except on

outcrops of hard rock formations, where the high and low tide lines will simply move up

the cliff face. Existing shore platforms and abrasion ramps will disappear beneath the sea.

2. The shores of deltas and coastal plains will retreat, except where they are maintained by

coastal sedimentation.

3. Beaches will be narrowed, and beach erosion will become much more extensive and

severe than it is now.

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4. Inlets, embayments, and estuaries will be enlarged and deepened, and increasing salinity

penetration will cause a regression of coastal ecosystems: where possible, mangrove and

salt marsh communities will move back into terrain presently occupied by freshwater

vegetation.

5. Coastal lagoons will also become larger and deeper, but the enclosing barriers may

transgress landward on to them. If the barriers are submerged, or destroyed by erosion,

the lagoons will become coastal inlets or embayment’s.

6. Low-lying areas on coastal plains, such as sebkhas (saline depressions now subject to

occasional marine flooding) on arid coasts, will be flooded to form permanent lagoons.

7. Upward growth of coral and associated organisms will be stimulated on fringing biogenic

reefs, keeping pace with the marine transgression or lagging somewhat behind it

(Neumann and Macintyre 1985).

8. Erosion, structural damage, and marine flooding caused by storm surges or tsunamis will

intensify because of the greater heights of waves arriving through deepening coastal

waters.

9. Water tables will rise in coastal regions, and soil and water salinity will be augmented.

Table 3. Summary of magnitude of some of the ecosystem services provided by mangroves. The

value of fisheries habitat and sediment trapping is considered for seaward fringing mangroves

(low intertidal) and high intertidal. Mg= mega gram or 1,000,000 g

Ecosystem service Stocks Rate of ecosystem service

or productivity

References and assumptions

Fisheries

Seaward fringe Fish 20 to290 kg

per ha

Prawns 450 to1000 kg per

year

Robertson and Blaber 1993, Blaber

2002

High intertidal Fish 6 kg per ha Mazumder et al. 2005, salt marsh,

reported as 0.56 fish per m2

(assuming 1 fish = 1 gram)

Sediment trapping

Seaward fringe 50 to 600 Mg per ha per year Furukawa et al. 1997, Saenger 2002,

Alongi et al. 2005

High intertidal 4 Mg per ha per year Furukawa et al. 1997 - 5 g per m2 per

tide, assume tidal inundation 20% of

each year

Nutrient and carbon

retention and cycling

Carbon storage 385 Mg C per ha 3000 to 3500 kg per ha per

year

Chimura et al. 2003 (reported as

0.0055 grams C per cm3 – assume

soils are 1 m deep and average bulk

density of 0.7 grams per cm3

Nitrogen storage 20 Mg N per ha 140 to 170 kg per ha per

year

Lovelock unpublished data derived

from ratio of C:N of 20 in sediment

organic matter

Carbon export TOC: 2640 kg C per ha per

year. DOC: 500-1500 kg per

ha per year

Dittmar et al. 2006, Twilley et al.

1992, Ayukai et al. 1998

Nitrogen export Total 35 kg per ha per year.

DON 25 kg per ha per year.

PON 18 kg per ha per year

Alongi et al. 1992

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Table 4. Outline of some of the major ecosystem services provided by mangroves within

Indonesia and the processes potentially impacted by climate change

Ecological services Impact

Habitat

Nursery for fauna

Sediment trapping

Carbon storage in sediments and biomass

Nutrient cycling

Hydrological damping

Fisheries and diversity

Fisheries and diversity

Water quality

Atmospheric carbon cycling

Water quality and coastal waters productivity

Water quality, protection from storms, erosion and

tsunamis

Box. 1. Evaluation of physical features of coasts for replanting mangrove during the process of

climate change especially 1m MSL rise in Indonesia (Map scale 1:25,000): Socio-economic,

political and management regimes.

1. The planting and management of mangroves cannot be separated from coastal zone

resource use plans as a whole. Further it is not possible to separate a replanting scheme

from mangrove forest management in general, because after it has been planted the area

has to be continually managed.

2. All areas are not suitable for mangroves. Even in favorable areas, if they are replanted

without management, the resource would be soon lost (e.g., ATM in Pekalongan). It is

therefore, essential to select replanting areas that will justify the effort for both replanting

and management.

Coastal stability Subsidence, emergence, stable

Substrate Type, texture, area size, depth, stability (erosion, deposition)

Freshwater Sediment, nutrients, circulation, flood

Adjacent area River delta, mudflat, forest, marsh (sedges and grasses), industrial,

agriculture, mangroves, seagrass area, or coastal road and housing

Topography Slope seaward area, within area, landward area (slope as percent)

Coast character Embayment, mild seas, exposed coast, and coastal projection

Reef face shape Concave reef face, straight reef face, convex reef face

Sea climate Mild seas, moderate seas, occasional storm waves, large swell, and

monsoons

Tide Frequency, amplitude

Width Minimum width, protection zone for erosion control, tidal zone, green

belt, buffer zone, rule-of-thumb

Box 2. Policy failures in term ICZM for 1m MSL rise issue in Indonesia.

1. Failure to tackle cross-sectoral management issues (MOF, MOMAF, MOHA, SMOE,

14

Bakosurtanal, LIPI, Badan Pertanahan Nasional, Dewan Perubahan Iklim, Dewan

Maritim Nasional, PemDa etc).

2. Lack of cross-sector consultation and stakeholders’ consensus in the development of

strategies and policies.

3. Failure to manage resource-use conflicts and to devote resources to uses that yield the

optimum benefit.

4. Failure to establish institutional and provide the resources necessary for effective

enforcement, and

5. Failure to demonstrate the contribution of coastal and marine areas to national socio-

economic development (Sukardjo 2009b).