J. Russell Hanley 1
[email protected]
The paper examines the opportunities for the development of integrated land-use management techniques in the coastal areas of the countries affected by the Asian tsunami of December 2004. The focus is on the use of integrated land-use techniques within the areas of agroforestry and silvofisheries to assist with the restoration of areas of coastal forests and mangroves that have been lost in recent decades through conversion to other land uses. Coastal forests (including mangroves) are valued for their role in coastal protection and the supply of ecosystem services, but throughout the region, the trend has been for these systems to be cleared for a range of other land-use options, even in countries which have legislated to provide a coastal forest buffer zone. The paper provides some examples of agroforestry and silvofishery models that are viable options for the development of a coastal forest buffer zone, which should be more attractive to both individual landholders and regional planners for both economic and ecological reasons. The paper examines why individual landholders do not appear to be implementing more integrated models of land use at the farm/household level, and makes some recommendations that governments could implement to influence the decisions made by landholders on their land-use options.
The Indian Ocean tsunami of December 2004 affected coastal areas of countries that were directly impacted by shockwaves generated by the earthquake off the island of Sumatra. The eight countries2 that were most affected by the tsunami sustained varying degrees of damage, including substantial loss of life and almost total destruction of coastal infrastructure and livelihoods in the most badly hit areas.
In the aftermath of the tsunami all the affected countries are engaged in reconstruction programmes in the damaged coastal areas. The various reconstruction programmes are generally expected to be both sustainable and equitable, in order to meet the requirements of both international donor agencies and government planning regulations.
However, assessments of the situation prior to the tsunami in the coastal zones of these eight countries has revealed a lack of detailed coastal management planning and also insufficient adherence in many cases to legal and planning instruments that were designed earlier to harmonize coastal development and promote maximum sustainable benefit.
Part of the reconstruction effort has therefore focused on the issue of better coastal management planning and implementation in the hope that in future, natural disasters of this magnitude might not have such devastating impacts on lives and livelihoods.
One common thread in the assessments of the impact of the tsunami is the belief that mangroves and other coastal vegetation types play an important role as a protective belt or buffer zone on coastlines, and that the removal of these habitats for the development of other land uses significantly exacerbated the impact of the tsunami throughout the region (see Wolanksi, 2006 for an overview).
The agencies charged with the tasks of rebuilding the coastal infrastructure and livelihoods of the tsunami-damaged regions are questioning whether it is feasible to incorporate a coastal forest buffer zone into the rehabilitation plans for devastated areas.
In a broader view, the incorporation of a coastal forest buffer zone into the rehabilitation and reconstruction plans for tsunami devastated areas is also seen by many as a prelude to the extension of the buffer zone concept to all coastal areas, not only those at risk from tsunami or storm surges. The rationale is that significant other values are also provided by coastal forest buffer zones, including both direct and indirect economic and ecological values.
Hanakunarak and Aksornkoae (2005) asserted that for sustainable coastal management and utilization:
In most instances, sustainability is dependent upon functioning natural processes that support the region's natural character. Increasing modifications of the coastal ecosystems by human activities, including industrial, commercial, residential and agricultural development, have altered the functional integrity of the ecosystem, which can seriously reduce the level of goods and services that they normally generate.
Throughout much of the area impacted by the 2004 tsunami, the lowlying land within the coastal zone was once covered by various natural forest types, including mangroves, freshwater swamp forest and coastal forest. Descriptions of some of these various coastal forest types, many of which were widespread throughout the region, can be found in Saenger (2002) and Whitten et al. (2000). In this paper, the term mangroves will be used to cover all species of flora typically found growing between the upper limit of the intertidal zone (Highest Astronomical Tide — HAT) and the average height of the sea (Mean Sea Level — MSL). All other coastal forest types, including freshwater swamp forests will be referred to collectively as coastal forest. The boundary between mangroves and adjoining coastal forest is often difficult to determine accurately, with a transitional zone often evident between the two habitat types. Defining the landward boundary of “coastal forest” is much more problematic and in this paper the term is used loosely to refer to lowland forests with a distinct maritime influence.
The time when most of the coastal forests in the region were pristine in both condition and ecological structure is long past, and most have been subject to various human pressures and exploitation for centuries. Exploitation has always included the direct use of natural products such as fuelwood, timber, fruit and other foodstuffs and these are uses which could be sustained if the level of exploitation did not compromise the capacity of the resource to regenerate. Other uses were non-direct, and today are widely described as ecosystem services, including such products as fisheries and other coastal forest fauna, coastal protection, channel maintenance and water filtration.
In addition, there has always been some level of conversion of natural coastal forests to other land uses, including agriculture, aquaculture, forestry, tourism and urban development. These conversions were usually, but not always, permanent and typically on a relatively small scale.
However, in recent decades population growth in most of the tsunami-affected countries has greatly increased pressures on coastal forest resources, and in particular there has been a marked shift away from the more sustainable usages of forest resources towards complete removal and conversion of these forested lands into other land uses, summarized by the identification of forests as the primary targets in many countries for agricultural and urban expansion (FAO, 2006).
The widespread removal and degradation of coastal forests and mangroves in the tsunami-affected countries in the decades prior to the 2004 tsunami was a consequence of the conflicts between competing interests for the use of coastal land. These conflicts are still present today and can be expected to become even more intense in the near future as population increases apply ever greater pressures for access to coastal land.
The development of an integrated coastal management approach to the reconstruction and rehabilitation of the coastal zone for each of the eight most affected countries requires detailed examination of the land-use conflicts that have promoted the widespread degradation and removal of coastal forest habitats within most, if not all, of these countries. It will not be possible to develop a meaningful strategy for the sustainable rehabilitation of a coastal buffer zone that comprises various types of coastal forests and mangroves unless we first develop a clear understanding of the reasons why coastal forests and mangroves are being converted to other land uses.
Passing references to the issues of land tenure systems and coastal development policies will be made in this paper, but the issues are examined in much more detail in the two other papers in this workshop series (Samarkoon, 2006; Kay, 2006).
The task of this paper is to examine whether it is possible to develop and implement sustainable, integrated land-use systems in the coastal areas of the tsunami-affected countries that provide ecosystem services like coastal protection through the re-establishment of coastal forest and mangrove systems, while at the same time maximizing the livelihoods that can be sustained within the coastal zone.
We begin by examining what is known about the importance of ecosystem services such as coastal protection, and contributions to offshore fisheries productivity. This section is followed by a brief explanation of the many direct use values of coastal forests and mangroves.
The types of pressures on coastal forests and mangroves are also briefly discussed with reference to both conversion to other land uses and overexploitation of the direct use products.
A brief review of the available information on integrated land-use management, particularly where the agriculture, forestry and fisheries sectors are recognized as having important and natural linkages and overlap is provided; examples of how the integration of land management and sectoral policies may yield benefits in coastal areas of Asian tsunami-affected countries are discussed and cover the existing use, and potentials for further development, of agroforestry and silvoforestry systems.
The social, environmental and economic costs and benefits of implementing policies that promote integrated land management approaches rather than single objective, single output land management are examined. The difficulties in achieving a desirable balance between local and wider community interests with respect to ecosystem services are also examined in some detail.
Finally, some practical methods and problems related to the implementation of integrated land management that accounts for resource linkages between sectors are discussed with some potential solutions in the context of post-tsunami reconstruction.
In this section the major ecosystem services are discussed with examples, including some assessment of the economic valuations of these services.
The full value of mangrove (and to a lesser extent other coastal forests) is often not recognized as many of the goods and services provided are not traded on markets and therefore have no observable value; some of the goods and services occur off-site and are not recognized as being linked to, or originating in mangroves (Spaninks and van Beukering, 1997).
2.1 Coastal protection
The devastation wrought by the tsunami of December 2004 has caused many to question whether the clearing and conversion of many coastal forest types, including mangroves, within the countries most affected led to a much higher death toll and loss of infrastructure than would have been the case if the coastal forest systems had remained intact.
Wolanski (2006) provided a useful summary of the roles of mangroves and other coastal forest habitat types in coastal protection and concluded that despite some controversy over whether the presence of mangroves saved lives in the Asian tsunami (Kathiresan and Rajendran, 2005; Kerr et al., 2006), there is no doubt that mangroves and other coastal forests provide tangible coastal protection services to the extent that the establishment of coastal green belts as buffers against storm and tsunami events is justified.
However, studies conducted on the effectiveness of mangrove and other coastal forest buffer zones against storm surges and tsunamis concluded that green belt zones of trees planted close together still need to be at least 100 metres wide to provide any real protection (Mazda et al., 1997; Hiraishi, 2005), even against small-scale events. It appears that once the height of waves impacting a mangrove or coastal forest reaches two metres or more, the forest will usually fail, and the trees themselves become part of the debris that causes damage further inland.
There have been attempts in recent years to quantify the value of coastal protection services provided by mangroves and other coastal forest types (Barbier et al., 2002; Sathirathai and Barbier, 2001; Spaninks and van Beukering, 1997; Wells et al., 2006).
2.2 Maintenance of coastal waterways
Wolanski (2006) cited evidence that mangrove trees play an important and largely unrecognized role in the maintenance of tidal waterways. There is a marked tidal asymmetry of the currents in the channels and estuaries that drain mangroves and the peak ebb tidal currents at the mouth of the creek are measurably larger than the peak flood tidal currents. This means that the channels tend to be self-scouring. Removal of mangroves increases siltation in the creek channels and can lead to the loss of a navigable channel, particularly at low tide levels. The value of this ecological service is not typically included in assessments of mangrove values, but is likely to be substantial as dredging of tidal channels and waterways is usually an expensive and repetitive exercise.
2.3 Filtration systems
Saenger (2002) provided a brief overview of the role of mangrove systems in enhancing estuarine water quality and cited published evidence that mangrove systems can:
The role of mangrove systems as “anaerobic digestion” systems for inputs of organic material and nutrients (e.g. sewage discharges, aquaculture wastes) is well-understood; consequently, the common practice of siting discharges of these wastes in, or near, mangrove systems has some logic, although it has rarely been the motivation behind discharging effluent into these systems. Recently there is more interest in the relatively new practice of constructing mangrove wetlands expressly for the purpose of treating effluent streams (Saenger, 2002). Recent studies in Indonesia (Ahmad and Mangampa, 2003) and Thailand (Tookwinas et al., 2003) have shown that mangroves can be effectively used to remove nutrients in the treatment of effluent from shrimp ponds.
Freshwater swamp forests and other coastal forest types can perform similar functions, dependent on local geomorphology. On many stretches of coastline throughout the wet tropics there is a gradient through forest types from coastal terrestrial forest, freshwater swamp forest and finally mangroves. Water bearing nutrients and contaminants that enters these systems from the hinterland can be subjected to similar biogeochemical processes that promote the settlement of fine, colloidal particles and the stripping of heavy metals from the water column. The level and type of water quality “polishing” is of course dependent on many factors, such as the characteristics of the water, local geomorphology and geology, the types and extent of forest and other wetlands present, tidal range and rainfall patterns.
The capacity of the various “sinks” within a system to absorb or modify the nutrients and other materials carried by the water will determine the eventual quality, and quantity, of the water emerging from the forests. Coastal forest systems are classified as “sinks” if most of the inputs of nutrients and contaminants are retained within the system, while others are “sources” of nutrients and contaminants if significant levels of these materials are exported from the system with the water.
The role of coastal forests as “sources” of various nutrients rather than sinks is not necessarily a negative one and the role of exported nutrients from mangroves and other coastal forest types in the productivity of offshore fisheries is recognized as important, but for many systems specific details of the linkages are lacking.
2.4 Fisheries productivity
Most work on the linkages between coastal forests and offshore fisheries production has focused on mangroves and there is little specific work on the role of freshwater swamps and riparian vegetation. In the wet tropics there is a gradient of salinity and water along which forest types are arranged and the boundaries between the various forest types are often ill-defined and may shift from season to season. The lack of clearly defined boundaries is reflected in the fact that the classifications of the habitats of various plant species along this gradient often differ, with the same plant described as a mangrove, a freshwater swamp species or part of the hinterland coastal forest association by different authors (e.g. Saenger, 2002; Whitten et al., 2000).
Therefore, much of the published information examining the role of mangroves in supporting fisheries production includes at least some components of what other authors would include in freshwater swamp and other coastal forest plant associations.
Manson et al. (2005) provided a comprehensive review of published information on the ecological and biological evidence for linkages between mangroves and fisheries production. The linkages between mangroves and fisheries production operate in at least four different ways.
1. Many coastal species utilize mangrove habitats as nursery grounds. Juveniles live in the mangroves and tidal creeks for some or all of the time and then as adults migrate offshore into deeper water where they are targeted by commercial fisheries — for example Scylla serrata (mud crab), Penaeus merguiensis (banana prawn), Penaeus monodon (tiger prawn) and Lutjanus argentimaculatus (snapper).
2. Some species live their entire lives within the mangroves and tidal creeks and many are targeted by local artisanal fisheries, e.g. Metapenaeus spp. (estuarine prawns) and Geloina erosa (bivalves).
3. A number of commercially important species enter the mangroves and tidal creeks each high tide to feed and include grazers such as Liza spp. (mullet) and large predators like Lates calcarifer (barramundi, kakap).
4. Another linkage is the role of mangroves in providing fixed organic carbon to offshore food chains via export of detritus. Much of the food chain base in mangroves is comprised of organic material from fallen leaves, which are broken down in, and on, the muds beneath mangroves. In many regions, at least a proportion of this material is exported out of the mangrove by the tide. The exported detritus and nutrients are then available to food chains in near and offshore waters.
The total contribution of a stand of mangroves to fisheries yields is therefore a sum of the aforesaid individual components.
For most stands of mangroves it is not possible to state with any certainty the value of each of the aforesaid components, either relative to each other, or compared to other similar systems. For example, the contribution to offshore fisheries production via export of detritus cannot be estimated for any particular system without some data on the flux of nutrients and detritus; moreover, measurements of this type are not yet widely available. Where measurements of nutrient and detritus flux are made, they show some mangrove areas are exporters (sources) and other areas retain most nutrients in situ (sinks).
The available data demonstrate considerable variability in the role of mangroves in sustaining fisheries production in all of the four aforementioned pathways (see Manson et al., 2005).
Usually mangroves growing at or near the equator in regions where there is no dry season and with substantial freshwater inflow are the most productive (Saenger, 2002); so intuitively these more productive mangrove stands probably contribute more to fisheries yields.
Most of the tsunami-affected countries have very productive mangrove systems by world standards (Saenger and Snedaker, 1993); therefore, it is likely that the contribution to fisheries yields from mangroves and other coastal habitat types in these countries is at the high end of the global range.
Positive correlations between mangrove area and shrimp/fish catches have been documented for many areas of the world, including the Philippines, Malaysia, Indonesia and Australia (Primavera, 1995; 1998). On the basis of these correlations between mangrove area and catch, Pauly and Inglis (1986) hypothesized a general, non-linear equation to relate intertidal vegetation (mangroves and saltmarshes) to fisheries yields which can be used to forecast Maximum Sustainable Yields (MSY).
MSY = f (Vegetation, Latitude)
log10 (MSY) = 2.41 + 0.4875 log10 (vegetation) - 0.212 (degrees
latitude)
This general equation was developed some 20 years ago and was based upon data available at that time and therefore may require some modification to incorporate more modern data sets.
At a local level, Dudley (2000) exploited a unique opportunity to examine the contribution of mangroves to fisheries in the Segara Anakan Lagoon and adjacent coastal waters, where the only substantial mangroves on hundreds of kilometres of the Javanese coastline could be assumed to support virtually all of the production of estuary-/mangrove-associated species in the region. The data indicated that the contribution from the lagoon mangroves and open water areas to fisheries yields (lagoon and coastal) was worth US$1 376 /hectare for mangroves and US$1 996/ hectare for open water in the estuary and was calculated by comparing the total fisheries values for species known to have linkages with estuaries/mangroves with the total areas of mangroves and open water within the estuary.
Other attempts to quantify the value to fisheries of mangroves and other estuarine habitats also show that the linkages are apparently substantial. Barbier and Strand (1998) estimated that the Campeche fishery in the Gulf of Mexico loses on average 0.19 percent of its annual revenue for every square kilometre of mangroves that is cleared. In Thailand, a similar study (Sathirathai and Barbier, 2001) estimated that the link between mangroves and offshore fisheries yields was US$21–69 per hectare and depended on the elasticity of demand and whether the fishery was open access or optimally managed.
The method used by Sathirathai and Barbier (2001) estimated fisheries values per hectare at several orders of magnitude below those calculated by Dudley (2000). The differences between the estimated values may be real and reflect differences in the ecology of the two locations or the differences could simply be a consequence of the different methods used to develop the estimates.
Barbier et al. (2002) discussed some of the various methods used to estimate the value of linkages between mangroves and other coastal habitats and fisheries; their modeling of the mangrove-fishery linkages in Thailand showed wide variation in the derived values when the input data/conditions of the chosen model were varied. For example, using their preferred model they calculated that an annual loss of 30 square kilometres of mangrove habitat translated into welfare losses ranging from US$12 000 to 408 000, depending on the elasticity of demand, and assuming an open access fishery.
Most attempts to quantify the value of unit areas of mangroves in supporting fisheries yields use either an ecological model or an economic model. The wide disparity between these two approaches, the lack of consensus about the parametres used within in each model and a lack of data about specific stands of mangroves means there is no current agreement on which approach is most suitable for estimating the linkages between mangroves and fisheries yields.
Despite the problem of satisfactorily quantifying the various linkages, it is possible to state with certainty that:
2.5 Maintenance of biodiversity
Saenger (2002) pointed out that there is already widespread acceptance of the usefulness of genetic, biological and ecological diversity in nature and that it is also accepted that the potential yields from currently unused elements of biodiversity could be very large.
Many coastal forest and mangrove habitats remain poorly understood in terms of genetic, biological and ecological diversity and therefore, the full extent of current and potential usefulness also remains poorly understood. Consequently, alterations to the functional components of coastal forest and mangrove systems may produce unforeseen and deleterious impacts elsewhere within the system, or in connected systems.
There is, as yet, very little published work on the valuation of biodiversity and virtually no models that have either wide acceptance or wide utility, but this is a growing area of research in environmental economics.
Direct uses are manifold (Table 1) and well-known throughout the region, although there are some differences in the way various species are used in different countries, suggesting that the full potential of direct uses has not always been fully explored.
There is a large body of literature that identifies the uses of coastal forest and mangrove plants in the region (see Hanley, 2006 for a recent review) and a number of publications also attempt to estimate the economic value of direct-use resources.
Table 1. Direct uses of
mangrove and other coastal forest trees (after Gammage,
1997; Saenger, 1981; Whitten et
al., 2000)
|
Uses |
Products and services |
| Fuel |
Fuelwood for cooking, heating, making charcoal, brick kilns, smoking fish and sheet rubber. |
| Construction |
Timber
for heavy construction – scaffolds, railroad sleepers, pit props. |
| Furniture |
Beds, chairs and tables. |
| Agriculture |
Grazing, fodder, green manure. |
|
Textiles, leather and beverages |
Synthetic
fibres, dyes, tannins for leather preparation, |
Estimating the values of the direct uses of coastal forest resources is less problematic than the estimates of non-direct uses, because the actual quantities of direct-use products can often be accurately determined. However, the estimates can also vary considerably and are dependent on the type of forest and its productivity, the types of direct-use products harvested and the method of estimating values.
A useful summary of various systems of valuing both direct- and non-direct-use products in mangroves can be found in Spaninks and van Beukering (1997); the data presented show there is wide variation in the estimates provided by different authors. Some of the variation is due to differences in the productivity of the forest, but most are attributable to differences in the range of uses identified and how their value is estimated.
The list of uses in Table 1 includes several tree products used for the manufacture of ropes, nets and dyes. The use of mangroves and other forest trees for manufacture of these products has become less common in recent times because of the advent of cheap and more durable synthetic fibres and dyes. The replacement of many direct-use products by other materials may have impacted negatively upon the perception of the value of coastal forest resources at the local community level.
The pressures on mangroves and other coastal forests can be conveniently divided into two categories:
4.1 Conversion to other land uses
A review of the impact of shrimp pond aquaculture on coastal wetlands (Lewis et al., 2003) suggested that within the Asian region as little as 5.3 percent of the area formerly covered by mangrove has been lost as a consequence of conversion to shrimp and fish ponds. The report contended that other land-use pressures have, in total, resulted in much greater losses of mangrove and other coastal forest habitats.
Other land-use pressures on coastal forests and mangroves include agriculture, urban growth, infrastructure (industrial) development, salt production and mining. Each of these different land-use pressures represents a small percentage of the total, but the total represents more than 50 percent of the former mangrove resources in many Southeast Asian countries. The same land-use pressures also apply to most other lowland forest types throughout the region and the general trend is one of loss of these natural resources as population growth increases the demand for land.
However, Primavera (1995; 1997; 2000) contended that although conversion to saltbeds, agriculture, settlements and overexploitation by coastal dwellers has caused mangrove decline, aquaculture remains the major causative factor, at least in Southeast Asia.
Certainly at local scales within the region, the percentage of intertidal land converted to shrimp ponds can be large. For example, within the tsunami-devastated NAD Province (Aceh), there has been a substantial and continuing conversion of mangrove areas to shrimp ponds since the 1980s. Lewis et al. (2003) quoted data from McPadden (1993) where studies carried out using satellite imagery during the early 1990s showed that 56 percent of shrimp ponds in Northern Sumatra were built on what had been (in 1977) primary forest areas, 15 percent in secondary areas and 29 percent in fringe areas without forest cover (McPadden, 1993). Thus, some 69 percent of the shrimp ponds in Northern Sumatra have apparently been built in mangrove areas (based upon data from the early 1990s).
As noted by Lewis et al. (2003), one factor which has led to the conversion of large areas of mangroves in many Southeast Asian countries has been that the ponds constructed are, for the most part, used for extensive shrimp and milkfish aquaculture. In the extensive aquaculture system, stocking rates are low, and therefore there is a tendency to make the ponds much larger than they would be for a semi-intensive or intensive operation. On the northeast coast of NAD Province, the majority of tambaks (brackish water ponds) were of the extensive type, described by Phillips and Budiman (2005), as shrimp and milkfish farms mainly operated as traditional, low input, farming systems.
Recent surveys of the northeastern coastline of NAD suggest that several species of mangroves are now locally extinct within the region as a consequence of the large-scale conversion to extensive shrimp ponds of suitable habitats for these mangrove species (Hanley, 2006).
4.2 Overexploitation of remaining coastal forests and mangroves
All of the eight tsunami-affected countries have experienced substantial population growth during the last two decades and the growth has been greatest in coastal areas. The pressure on coastal forests and mangroves has increased, particularly with respect to demands for timber, fuelwood and charcoal; in mangrove habitats there has also been increased pressure on fisheries products such as crabs, shrimps, fish and bivalves. The loss of substantial areas of coastal forests and mangroves through conversion to other land uses has contributed to the increasing pressure on the remaining stands and, throughout the region, continuing degradation and depletion of these resources is a common trend (Lewis et al., 2003; Saenger, 2002; FAO, 2006).
Excessive logging for timber, charcoal and fuelwood (and woodchips) in many areas has removed most or all of the mature trees (Saenger, 2002); consequently the use of mangroves and coastal forests as sources of timber for heavy construction use (pilings, large beams) has declined. The remaining stands of trees are typically cut repeatedly for fuelwood and charcoal production. The overexploitation of mangrove species at many locations has led to a general lowering of the canopy height, and a shift in species composition away from species that are killed when the central stem (trunk) is cut, with an increase in those species which coppice easily after cutting (Hanley and Haryanto, 2000).
In all of the eight tsunami-affected countries there is a general and continuing trend of forest loss (FAO, 2006), highlighting that the loss of forest resources in these countries is not confined to mangroves and coastal forest types.
4.3 Coastal forests and other land uses can co-exist
Despite the apparent universal trend of declining forest resources in all of the tsunami-affected countries, the conversion of mangroves and other coastal forests to other land uses need not necessarily lead to the complete elimination of coastal forests. Some land uses such as agriculture and aquaculture could incorporate (or retain) substantial stands of coastal forests in polyculture systems. There are already a number of polyculture systems that include coastal forests and mangroves and these appear to be viable systems that are comparable with monoculture systems.
Similarly, urban and industrial development can co-exist with coastal forests as part of a mixed land-use pattern. For example, coastal forests can act as buffer zones between industrial areas and urban developments, or as coastal protection zones.
In this section several models of integrated land management practices suitable for the tsunami-affected areas are discussed with examination of the benefits and costs associated with each. The examples presented are not considered to be the best (or only) solutions, but serve to illustrate that it is possible to develop a variety of mixed land-use models that incorporate coastal forests, including mangroves.
5.1 Agroforestry
Jensen (1995a) defined agroforestry as the deliberate cultivation of several productive components, of which at least one is a woody perennial, on the same piece of land, combined either spatially or sequentially.
The term "agroforestry" is relatively new (Jensen, 1995a) and agroforestry systems may be included in several of the categories usually applied in land-use statistics such as: forest land, wood land, degraded land, agricultural lands, urban areas (homegardens) and "other land use" (e.g. roadside plantings).
While the term may be new and broadly applied to a range of agriculture/forestry practices, many of the land-use systems which are covered by the term have a long tradition throughout the region.
In Sri Lanka for example, Ariyadasa (2002) reported that more than 70 percent of the industrial timber and more than 80 percent of the biofuel demand is derived from different types of tree resources outside the traditional forest areas, including homegardens, coconut plantations, rubber plantations, shade trees in tea plantations, roadside plantations, trees on farmlands and other perennial plantations. Homegardens are estimated to have covered about 895 000 hectares in 1992, and to be the best developed and oldest agroforestry system in Sri Lanka, with mixed cropping of a variety of tree species that provide food, fruits, timber, medicine and spices (Ariyadasa, 2002).
Most examples of traditional agroforestry systems are based upon gradual modification of the original natural forest type occurring in an area by selective removal of undesirable species (often used as fuelwood) and retention (including planting) of desirable species.
The selection of tree types for development in an agroforestry system is in part dependent on traditional knowledge of the products and uses of particular species, and also on the farmers’/landholder’s assessment of the options available for a specific piece of land.
In the past 30 years agroforestry has also progressed from traditional practices (varying in form and structure from region to region) to the point where development experts agree that it provides an important science-based pathway for achieving important objectives in natural resource management and poverty alleviation (Garrity, 2006).
Agroforestry now encompasses a wide range of working trees that are grown on farms and in rural landscapes, including the generation of science-based tree enterprise opportunities such as fertilizer trees for land regeneration, soil health and food security; fruit trees for nutrition and income; fodder trees that improve smallholder livestock production; timber and fuelwood trees for shelter and energy; medicinal trees to combat disease; and trees that produce gums, resins or latex products (Garrity, 2006).
The long history of agroforestry systems in the region and the recent successes in developing new agroforestry models with wider application suggests that the problem of coastal deforestation and degradation of forest buffer zones in the eight tsunami-affected countries could be overcome with the development and/or selection of appropriate site-specific agroforestry models.
While many of the traditional agroforestry models have a long and widespread usage, recent success stories for new agroforestry models have been largely confined to localized sites, and typically with unusually concentrated institutional support from research and development organizations (Franzel et al., 2006).
In a review of the problems associated with scaling up three different agroforestry systems, Franzel et al. (2006) concluded that there is no single recipe for scaling up and that a number of different approaches can all be successful, depending on the innovation, the environment and the resources at hand. They identified the following key elements that contributed to improved impact in the case studies:
This list of key elements has been identified in many other development projects with a focus on agriculture and forestry, and suggests that the promotion of new agroforestry models in the tsunami-affected areas would require a considerable investment of capital and expertise over a time scale of several years. Lack of investment capital (private and/or public) and lack of expertise among target landholders and government extension services are often significant barriers to the successful scaling up of agroforestry models.
However, the generosity of the donor community has created a unique opportunity in the tsunami-affected countries as it appears the donor agencies and donor nations have the required capital already available, although insufficient expertise and institutional support in both planning and implementation strategies within the affected countries remain major impediments.
There are also a number of other constraints to the success of any proposed agroforestry systems and these relate to the attitudes and options available to the landholders who would implement and maintain the systems. The motivations of individual landholders and their constraints are discussed in more detail in the section on decision-making at the household and community level, but it is worth mentioning some of the constraints on the adoption of agroforestry systems here.
In a review of the commercialization of non-timber forest products (NTFPs), Marshall et al. (2006) observed that the importance of NTFPs in household livelihood strategies is closely linked to their seasonality and the way they may be combined with other income-generating activities. The more months a product can be traded, the more favourably households view the activity. Conversely, households involved in seasonal products are more likely to switch from NTFP activities to other livelihood options, reflecting their desire for a more consistent and year-round source of income.
The seasonality of various non-commercial NTFPs would also influence smallholder decisions about whether to plant and tend trees that develop products which would be used by the smallholders themselves rather than traded.
Similar considerations would also apply to timber products from agroforestry because timber products are constrained by a relatively long time span before a smallholder can realize a return on the investment of capital and labor in trees planted and maintained for timber.
As the seasonality of many agroforestry products is a major factor influencing smallholders to adapt their farming practices to include the products, then it is logical to assume that agroforestry products that are available year round should be generally favored over other products that are seasonal, if other factors such as investment costs and the length of time before yields for different agroforestry products are equivalent.
Two agroforestry products that are typically available year round are fuelwood and fodder, suggesting that perennial species which produce these crops should be favoured by smallholders.
A wide variety of agroforestry systems that includes a mixture of perennial crops and annual crops could be applied to the tsunami-damaged areas, but would be largely restricted to areas formerly occupied by coastal forest as most of the species are precluded from growing in the intertidal zone. This is particularly true of food products from perennial crops such as fruits and nuts, and also for fodder and green manure. While several mangrove species produce fruits, propagules and leaves that are edible, they are usually only eaten when other options are limited and often require substantial treatment before consumption. Similarly, while some Rhizophora, Avicennia and Ceriops species are used as fodder for herbivores such as goats, sheep, cattle and camels, they often lack the full complement of nutrients (Saenger, 2002). Honey production from mangrove trees appears to be restricted largely to Avicennia spp. and also Aegiceras corniculatum (Hanley and Haryanto, 2000).
However, many species of mangrove tree are valuable sources of timber and fuelwood/charcoal (Inoue et al., 1999; Saenger, 2002) and so the examination of suitable agroforestry systems primarily aimed at the production of timber and fuelwood is relevant for both former coastal forest habitats and former mangroves.
At the interface between coastal forest and mangrove there is often a mixed association of species from both forest types and land cleared for agriculture here is often used for the production of brackish-water rice. The development of agroforestry systems at the upper levels of the intertidal zone could include mangrove tree species for fuelwood or timber production.
Bhattarai (1995), Jensen (1995a,b) and Bhattarai et al. (1997) provided evidence for the importance of fuelwood production on non-forest (i.e. non-public forest land) in Southeast Asia and suggested that the development of agroforestry systems is primarily based upon integrating woodlots for fuelwood/timber production with crop production and can function over both long- and short-term cycles.
While it is true that a greater variety of agroforestry systems with different aims and crops have been developed in the last several decades, the development of fuelwood supplies is still of primary importance to many of the smallholder farmers engaged in agroforestry.
Bhattarai (1995), reviewed fuelwood usage, and other energy sources in eight Southeast Asian countries, including four of the eight tsunami-affected countries: Indonesia, Myanmar, Malaysia and Thailand. The data presented show that for the majority of the people as well as for many different industrial, commercial and processing activities in rural areas, woodfuels and other forms of biomass (i.e. animal dung, crop residue, industrial waste, etc.) or other traditional sources are still the only available forms of energy. The domestic sector in particular requires woodfuels (most often non-traded items) primarily for cooking, heating and processing of agricultural products, mostly for consumption within the household. The commercial and industrial sectors require woodfuels for production or processing of items in bulk for the market. In rural and peri-urban areas, traditional sources are still preferred over commercial or conventional energy sources (i.e. kerosene, coal, electricity, LPG, etc.).
Bhattarai (1995) concluded that this was probably because of reliability of supply and affordability of use, as woodfuels are still comparatively less costly than other conventional energy sources in many peri-urban and rural areas. Therefore, many rural industries and some specific commercial activities in urban centres (e.g. eateries, bakeries, smithies, etc.) still use a substantial amount of woodfuel for energy.
Although Bhattarai (1995) noted that in Indonesia, Malaysia and Thailand the proportion of energy derived from fuelwood was declining relative to total energy consumption, the total volume of fuelwood used for energy did not appear to be declining at all, and in Myanmar it appeared to be increasing. Bhattarai et al. (1997), in a comprehensive review of current and future fuelwood use, predicted that the consumption of wood and other biomass fuels would increase in all of the eight tsunami-affected countries in the forecasting period (up to 2010), due to population growth, even though the proportion of fuelwood-derived energy would fall relative to total energy use over this period.
The growing awareness of the role of “trees outside forests” or TOF, now extends to the understanding that it is not just smallholder farmers, but also nearby village and urban dwellers who benefit from access to trees found on non-forest and non-wood lands such as agricultural lands, urban and settlement areas, roadsides, homegardens, hedgerows and pasture/rangelands scattered over the landscape (Sadio and Negreros-Castillo, 2006).
Given the projected growth of demand for fuelwood supplies in all eight of the tsunami-affected countries and the suitability of fuelwood crops for both coastal forest and mangrove habitats, the development of suitable fuelwood agroforestry systems for the supply of both domestic and commercial demand should be a high priority.
The selection of suitable fuelwood species is highly dependent on local conditions, but Jensen (1995a) listed some general criteria:
Another critical factor is how much woodfuel can be produced per unit area of land and Jensen (1995a) reported that precise data are often lacking primarily because the majority of woodfuel collected is for home use and is not traded.
Jensen (1995a,b) provided some estimates of the reported annual fuelwood supply of a range of agroforestry systems and included the characteristics of some mangrove species that are sources of fuelwood. He also provided estimates of how much land is required to provide woodfuel for a household and also the number of trees per hectare required to supply a household. However, he warned that these estimates are not likely to be accurate, as they are based on limited data sets and in many cases do not take into account that farmers often plant a variety of trees for a variety of purposes.
In summary, the wide variety of agroforestry systems now available and the projected growth in demand for wood (especially woodfuel) and other products from forests suggests that many of the current problems of deforestation in coastal areas could be overcome by the development of site-specific agroforestry schemes.
5.2 Silvofishery
Silvofishery is a type of agroforestry system which is often cited as a viable option to counter the continuing degradation and loss of mangrove habitats throughout the region.
The basic concept is to develop both aquaculture and mangroves as components of a single system that provides income to the smallholder through a variety of sources. The concept is apparently a very old one and stems from at least the early fifteenth century in Java, where traditional tambak can still be found in the Solo–Brantas Delta of East Java in which tidal wetlands are formed by the complex of ponds which retain mangroves on dykes, as strips between ponds or in remnant patches inside ponds.
Individual ponds are one to four hectares in size and ecologically similar to tidal lakes; the landscape of mixed ponds and patches of trees also provides wildlife habitat, contributes aesthetic and amenity values and enhances the living environment of human settlements (Davie and Sumardja, 1997). Although the diversity of flora and fauna in this type of landscape is usually higher than it is in areas where mangroves have been completely cleared, it is not typically as diverse as many undisturbed stands of mangroves (Hanley, 2006).
This type of “extensive” aquaculture system comprises shrimp and milkfish farms which mainly operate as traditional, low input, low stocking density farming systems (Phillips and Budiman, 2005) and was the most common type of aquaculture development present on the north-east coast of Sumatra prior to the tsunami.
The stocking rates are low in these extensive systems and although there is an opportunity for capture of wild stocks inside the ponds, the level of predation is typically high; the overall productivity of the pond is low because of limited, or no additions of feed or fertilizers.
Davie and Sumardja (1997) and Inoue et al. (1999) reported that mangroves are planted on pond dykes and adjacent tidal flats to:
Some patches of mangroves are also often left on the raised platforms in the centres of ponds, partly because it reduces the cost of clearing. The species most favoured for this purpose, and also for planting on dykes are Avicennia marina, Rhizophora mucronata, Excoecaria agallocha and Xylocarpus moluccensis (Davie and Sumardja, 1997; Inoue et al., 1999).
Interestingly, Primavera (2000) also noted that the Forestry Department in Indonesia prefers to plant Rhizophora on dykes and on central platforms in ponds because the propagules are easier to raise and the species are believed to resist prolonged waterlogging; this may be a source of tension with local people who prefer Avicennia spp.
Hanley (2006) contended that another motivation for the planting of Rhizophora spp. may be because under Forestry Law in Indonesia all Rhizophora forests are the property of the Forestry Department.
There are other practical reasons why Hanley (2006) recommended that Rhizophora spp. should not be used for plantings on dykes, because once the trees reach even a modest size, their prop roots will block access along the dyke, their leaves are highly refractory and acidic, and also because trees of this genus do not coppice so they are unsuited for sustained fuelwood extraction. There is also some evidence that the roots of mangrove trees can reduce the effectiveness of bunds as dead roots eventually rot away leaving channels in the bunds, although it is likely that burrowing crabs and the mud lobster cause much more damage to bunds.
At present, virtually all plantings of mangroves in and around aquaculture ponds in Aceh are Rhizophora spp., primarily because there is a lack of awareness that other species of mangrove are better suited, and also because suppliers of mangrove seedlings are not requested to supply other species and therefore have no incentive to invest in developing the nursery stocks (Hanley, 2006).
In addition to the traditional forms of mixed extensive aquaculture and mangrove forestry there has been widespread interest in recent years in the development of integrated silvofishery models sponsored by the state in a number of countries.
There are two basic forms of silvofishery. They comprise systems that are similar to the traditional systems of Indonesia where some mangroves are retained inside the pond and also around the perimetre (on the dykes), and a second form where the mangroves are all outside the ponds. Primavera (2000) provided a good summary of the various state-sponsored and traditional models used in several countries. Tuan et al. (1999) and Clough et al. (2002) examined in detail the state-sponsored silvofishery systems currently operating in Vietnam.
Primavera (2000) noted that systems where mangroves are located inside the ponds are not usually favoured by farmers because there is more work required to both construct and maintain the system and also because the shade from the mature mangrove trees lowers the phytoplankton productivity in the pond and therefore depresses yields of fish and shrimp.
However, while management of the separate pond-mangrove system is easier than the form with trees inside the ponds, the separate system may be more vulnerable to illegal pond expansion into the adjacent mangrove area.
Apart from the direct potential products of timber, fuelwood and fodder from the mangroves and fish, shrimp, crabs and bivalves from the ponds and associated intertidal areas, all the systems can also be more complex and include a variety of domestic livestock (pigs, chickens, ducks, goats) and other types of tree, vegetable, fruit and honey production (Tuan et al., 1999; also Angel, in Hanley and Hariyanto, 2000).
The earth removed from ponds is typically used to elevate dykes above the height of spring tides; after leaching of salt they can be used to grow vegetables and other shallow rooted plants.
Primavera (2000) reviewed the performance of various “mangrove friendly” silvofishery models (MFA) in Indonesia, Hong Kong Administrative Region, Malaysia, Vietnam and the Philippines and concluded that:
The yields of shrimp and milkfish reported by Primavera (2000) for extensive ponds without seeding or addition of feeds are comparable with the yields of less than 500 kilograms/hectare/year reported by Phillips and Budiman (2005) for the areas of extensive aquaculture ponds that were severely damaged by the tsunami in Aceh Province.
These are low yields relative to the semi-intensive and intensive models of brackish water aquaculture where much higher yields are possible; naturally these more intensive operations also require significantly greater levels of investment in both technology as well as seed and feed stocks juxtaposed by substantial technical skills.
At present, it is highly unlikely that the majority of smallholders who currently own or manage extensive aquaculture ponds have access to the capital and expertise required to upgrade their operations to semi-intensive or intensive levels. With significant investment in the rehabilitation of aquaculture ponds by donor organizations in the eight tsunami-affected countries, there is the potential for the development of more intensive systems.
While recommending the rehabilitation of many extensive aquaculture ponds as a short-term response to the economic displacement caused by the tsunami on the Aceh coastline, Phillips and Budiman (2005) also recommended that mid-term solutions should include:
As discussed earlier, the issue of establishment and maintenance of a green belt is a contentious one, particularly as the majority of the ponds in Aceh were originally sited in the area which is mandated by law as a green belt zone, although much of this development may have occurred before the zone was declared in law. To date, in Aceh Province, there is no sign of any replanning of severely damaged tambak areas; many tambaks that lie inside the green belt zone have simply been, or are planned to be, rehabilitated (Hanley, 2006) with little regard for wider coastal zone management issues such as the provision of green belts.
Lewis et al. (2002) reviewed the problem of shrimp pond development in mangrove areas and concluded that extensive ponds are the biggest cause of mangrove removal because they are built lower in the intertidal zone within the region typically occupied by mangroves, and tend to be much larger in area because the yields per unit area are so low. So it appears that the low technology type of brackish water pond is most likely to be incompatible with the green belt as it must usually be sited within the area that should be developed as a green belt.
By contrast, Lewis et al. (2002) asserted that semi-intensive and intensive shrimp ponds are much smaller in area (with much higher yields per unit of area) than extensive systems and are best sited above the upper limit of the tide (so that they can be easily drained when needed). The report contended that mangrove areas are generally unsuitable for semi-intensive and intensive pond development for a host of reasons.
Therefore, it is a reasonable proposition that government agencies and donors engaged in tsunami reconstruction and rehabilitation should examine the opportunities for relocating at least some of the brackish water aquaculture ponds above the intertidal zone and convert them into semi-intensive and intensive operations. The area required for the same output would be much smaller than is currently the case and it removes the ponds from the zone, which could then be developed as a green belt.
5.3 Other uses for coastal forests and mangroves in coastal land management
If many of the extensive ponds occupying former mangrove areas were replaced by the development of semi-intensive and intensive ponds above the upper limit of the tide, then the former productivity of the ponds could be met by a smaller footprint of more technologically advanced ponds, leaving the intertidal zone to be planted with species of mangrove that could provide a sustainable source of fuelwood and other NTFPs; it could also serve as a green belt buffer zone providing some level of shoreline protection.
One of the major problems associated with the large-scale development of aquaculture ponds in the intertidal zone is that poor development planning often leads to severe impacts on the quality of water available, as effluent streams from ponds are mixed with water intended to supply other ponds.
As discussed earlier, the potential role of mangroves as filtration systems for the maintenance of water quality is now much better understood and the siting of semi-intensive and intensive ponds above the highest tides provides an opportunity to develop mangrove systems that would receive and filter effluent streams from ponds.
In the context of a more systematic approach to development planning in the coastal zone, mangroves and other coastal forest types could be used as buffer zones around tourist developments and coastal industrial estates and ports. The use of vegetation as buffer zones to provide privacy or to shield tourist resorts, housing and other residential developments from noise and visual pollution associated with heavy industry is widespread, but has not been exploited as widely as it could be in any of the eight tsunami-affected countries.
It is also worth noting the increasing interest in the use of agroforestry and other tree cropping systems as the basis of carbon sequestration to offset greenhouse gas emissions. The majority of schemes that have been established or are currently under discussion typically involve large areas of land; however, the options and likely outcomes for smallholders engaging in a “clean development mechanism” approach to agroforestry are under investigation. Suyamto et al. (2006) and Roshetko et al. (2006) concluded that it is possible for smallholders to participate successfully in carbon storage, although there are higher transaction costs.
There are obviously a considerable range of options available for the integration of trees into coastal landscapes in ways that provide multifunctional outcomes for a range of beneficiaries.
The decisions about what types of agroforestry or silvofishery models might be adopted rest partly with the smallholders occupying and using coastal and intertidal land and the communities they belong to.
The focus of this paper is on the use of integrated land-use techniques within the areas of agroforestry and silvofisheries to assist with the restoration of areas of coastal forests and mangroves that have been lost in recent decades through conversion to other land uses.
Consequently, it is useful to examine the factors that influence the decision-making process at the farm household level (Figure 1) which has led, and continues to lead, to smallholders/farmers making decisions to convert coastal forests, and particularly mangroves to other uses.
French (1995) observed that each farm household has a unique set of socio-economic and biophysical conditions; agroforestry technology and investment decisions are evaluated by farmers and agricultural entrepreneurs based on key external factors including:
Many factors have to be considered by farmers in their decision-making processes (Figure 1) and many of them interact. French (1995) disaggregated the decision-making process into investment and marketing decisions and production and conservation decisions. French (1995) also pointed out that people do not use a linear decision-making process and farmers consider many factors simultaneously.
French (1995) divided the factors influencing farmers’ decisions into on-farm factors (land tenure, household structure and division of responsibilities, biophysical) and off-farm factors (markets and market channels, policies rules and regulations, support services, technical information).
Off-farm factors such as market prices of the various commodities and their volatility are determined by the surrounding economy and include the wage rate for off-farm and out-of-the landscape labor opportunities (Suyamto et al., 2006).
In a review of why smallholder farmers often fail to invest in, or adopt natural resource management technologies like agroforestry and silvofishery systems which could lead to reforestation or maintenance of coastal forest and mangroves, Scherr and Hazell (1994) described the following major constraints:
At least some (if not all) of these constraints are present at least some of the time in regions where both coastal forest and mangroves have been, and are being cleared, by smallholders in favor of other land-use patterns.
6.1 Risk minimization
Upton (1996) asserted that tropical farmers are risk-averse and are willing to forego some income, on average, in adopting strategies to avoid or limit the effects of risk. Consequently, farmers will diversify their productive activities, adopt mixed and sequential cropping and avoid risky or untried products. French (1995) observed that different farmers also have varying risk tolerance levels based on savings and basic food security and that subsistence farmers tend, therefore, to have less tolerance for risk because they are closer to the borderline in terms of savings and liquid assets.
Budisarsono et al. (2006) contended that the socio-economic characteristics of farmers’ households are an important influence on the type of their tree garden (agroforestry) system and its economic productivity.
Thus, many subsistence farmers should be conservative in their approach to decision-making, relying on what has worked in the past and avoiding the new and uncertain; it would also seem that the best approach to uncertainty is to diversify, and thereby spread the risk by multicropping for those subsistence farmers with a low tolerance of risk.
6.2 Land tenure and investment
French (1995) stated that a central factor affecting investment, production and conservation decisions at the farm household level is the farmer's level of control over his or her land. Farmers with secure tenure are much more likely to think of long-term production and conservation activities than sharecroppers or migrant laborers.
They are also much more likely to invest in longer term strategies of land-use planning, including tree crops in agroforestry systems, and also more likely to have access to credit if necessary. The amount and types of land under stewardship of the farm household is therefore a critical factor.
In some countries, accreting areas of intertidal land can be transferred from common property ownership (or no ownership) into the hands of collectives and individuals through traditional village-based legal systems. Often the land is assigned to collectives or individuals with the provision that they make use of it within a certain period of time; often the best demonstration that intertidal land is being used, is to clear it and construct extensive aquaculture ponds or brackish water rice paddy (Hanley and Hariyanto, 2000).
Another incentive to clear mangroves from accreting intertidal land in Indonesia is because once such land becomes colonized by Rhizophora spp., the trees automatically pass into the jurisdiction of the various forestry agencies (Hanley and Hariyanto, 2000).
6.3 Have farmers consistently made the wrong decisions?
A common feature of the coastal zones of all the tsunami-affected areas is that the same process of degradation and loss of coastal forests and particularly mangroves prevailed commonly prior to the tsunami.
While the causes of deforestation are manifold, the role of smallholders in deforestation of coastal forest and mangroves for the purpose of farming is an important component of the total losses of these habitat types.
Does the loss of coastal forest and mangrove represent poor decision-making by the farmer/smallholder/landholder, which can largely be explained by reference to the many constraints outlined above?
Or are farmers making decisions that are fundamentally sound based upon their individual circumstances, which favor loss of coastal forest and mangroves over retention of these systems?
We can always assume that the farm household is striving to make the best decisions with respect to the land-use options available, and we also need to recognize that failure to make good decisions consistently carries a high price, particularly for subsistence farmers.
Determining if a farmer has made the best decisions on whether to proceed with a monoculture cropping system or a polyculture system including agroforestry on a parcel of terrestrial land that was formerly occupied by coastal forest is not possible without a more detailed view of the specific situation of individual smallholders with respect to all of the factors that bear on the individual farmer’s decisions (Figure 1). The inability to generalize is because there are so many permutations of cropping systems available, including the many agroforestry systems.
What is clear is that there are likely to be a number of potentially equivalent agricultural systems that include agroforestry; some of these systems can incorporate tree species that were part of the coastal forest that formerly occupied the land. At least some of the newly cleared farmland is used for production via agroforestry systems and many are stable systems.
With respect to the clearing of mangroves for the production of extensive (or more intensive) forms of aquaculture, the situation is much less complex as there are fewer alternative agriculture-based systems that are possible on intertidal land.
There has been much discussion of the potential role of silvofishery models as a solution to the problem of conflict between the right of local communities/landholders to maximize their economic opportunities (timber, fuelwood and aquaculture development) with the rights of the wider community (ecosystem services).
One of the central problems frequently cited (Primavera, 2000) for silvofishery models is that the stands of tall trees create shade over the pond areas; this appears to reduce the production of the algae that drive the fishery production in the pond. However, Clough et al. (2002) suggested that this is not a major problem and can be avoided by using the model where trees and ponds are not incorporated together.
Some of the various silvofishery models have been demonstrated for considerable periods of time (several in Indonesia have been operating for more than 20 years), but as yet there are no comparative economic assessments that compare the productivity of these systems to monoculture systems of either forestry or aquaculture. This is a serious information gap for both landholders and government.
It is also significant that very few local farmers have adopted these silvofishery models on their own without the added incentive of government subsidies. This is in direct contrast with the strong drive among many coastal farmers to continue the conversion of mangroves into shrimp ponds and strongly suggests that the silvofishery models are not attractive for most individual/collective landholders. Certainly in Aceh Province there is little interest among farmers with damaged aquaculture ponds for a mixed silvofishery model (Hanley, 2006).
van Noordwijk (2006) noted that despite concerns of virus disease on the most profitable shrimp, the aquaculture operations in Aceh can still absorb much labor (630 person days/hectare/year) and the price of labor approximates IDR50 00019/day), which is substantially above other types of agriculture. Therefore, any reduction in tambaks linked to coastal protection will have to provide attractive economic alternatives.
If silvofishery models are to be embraced in any of the eight tsunami-affected countries, they must be seen to be economically attractive, otherwise there is no incentive for landholders to adopt them.
6.4 Who benefits and who pays?
Comparative assessments of the value of services derived from mangrove forests consistently conclude that the full range of services provided by mangroves is more valuable than the returns from other uses of the same land (Gammage, 1997; Barbier et al.,2002), but this is primarily because of the added value of the ecosystem services provided by mangrove habitats.
The issue of ecosystem services is problematic in terms of who derives the benefits from these services.
For example, individual/collective landholders may be invited to participate in a reforestation project that will require a decade before it provides dividends to the landholder in terms of direct uses and products such as timber. While ecosystem services begin to flow much earlier, they are not the exclusive property of the individual/collective landholders and therefore, are much less of an incentive than the potential direct uses.
There is a major conflict of interest between the wider community that derives benefits from ecosystem services provided by mangroves and the individual/collective landholders who wish to maximize individual returns from a piece of land under their jurisdiction.
Much of the justification for conservation and reforestation projects for mangroves in particular rests upon on acceptance of the importance of the ecosystem services provided.
However, individual landholders will make decisions about land-use options based upon direct uses and products and the time required to realize a return on their investment. They will disregard the value of the ecosystem services because the returns from these services are very small relative to the comparative values of various land-use options that provide direct uses and products.
The opportunity cost of ecosystem services lost when mangroves habitats are converted to other land uses is not borne entirely (or at all) by the landholders who clear the mangroves. If they are forced to retain the mangroves, then the value of alternative opportunities foregone by them are considerable, as they derive little benefit from those ecosystem services relative to the other land-use options they could pursue.
Is it possible to shift the burden of the opportunity cost associated with maintaining ecosystem services away from the individual landholders/communities and on to the wider community that is the real beneficiary of the ecosystem services?
In this section the role of government is examined with respect to altering the decision-making process at the household/community level to promote longer term outlooks, the integration of land-use practices and planning and the establishment and maintenance of a buffer zone.
7.1 Land tenure
As security of tenure is recognized as a major incentive in the consideration of long-term plans at the farm household level, then government initiatives to provide security of tenure to more of the population living in the coastal zones would kindle more interest in agroforestry and silvofishery systems, which require a long-term commitment by the landholder.
Many people who occupy coastal lands containing forest are considered by government to have no right of tenure, although many have a long history of association with, and use of forested lands in the coastal zone.
As van Noordwijk (2006) pointed out in a review of integrated land management issues in Indonesia, there are often multiple claims of “ownership” over forest lands. Development of a positive role for the local communities surrounding forest areas in managing and deriving benefits from the forests has often paid dividends, including a two- to threefold increase in asset value of the land managed, real commitment to protecting the remaining forests and decrease in income inequity in the communities concerned (Suyanto, 2006).
Major progress on “illegal logging” and other access issues can be made when the land tenure conflicts are mapped and addressed, when local communities receive respect and a role in forest management, and when the role of institutions that are supposed to support law enforcement is openly investigated (van Noordwijk, 2006).
A review of regional forestry policies in Asia (Enters et al., 2003) concluded that the shift from exclusionary to participatory forestry views people as part of the solution to problems in forestry, although foresters have been slow to adapt to the expanding demands by civil society and their own diminishing role in forest production and protection.
7.2 Policies, rules and regulations
van Noordwijk (2006) observed that economic actors in Indonesia respond to long-term trends as well as uncertainties and noted that several food crops and sugarcane are effectively “protected” and “subsidized,” while smallholder timber is still taxed. He suggested that a change in high-level policies in this regard is likely to have more effect than many well-intentioned attempts to develop “technologies” for agroforestry, afforestation or integrated farm management.
Similar inconsistencies in the taxation of natural resource products apply in the other countries affected by the tsunami and they distort the incentives for smallholders.
Another area of concern is the lack of rigor in the development of policies for state-sponsored silvofishery schemes where, for example, the proportion of pond area to mangrove area is set by regulation, without regard to the impact on the smallholders’ incentives (income). So in Indonesia, the official area ratio of Empang parit silvofishery systems is 80 percent trees and 20 percent ponds. The economic rationale behind this is not clear, particularly when the very few studies that have attempted to determine the optimal ratio of pond area to tree area (e.g. Inoue et al., 1999) considered a 50 to 50 percent ratio as optimal.
A concerted effort to implement the development of coastal green belt zones will require a comprehensive review of many different elements of government policy and a commitment to making the policy changes necessary.
Enters et al. (2003) indicated that policy implementation is hampered by macroeconomic and extrasectoral policies that frequently counter forest policies and may carry more weight than them. This is evident with regard to deforestation, which is certainly not driven by forest policies.
The general approach to coastal planning and development needs to be improved to at least some degree in all eight of the tsunami-affected countries; the best mechanism to achieve better outcomes would be the development of plans based on zoning. This is discussed in some detail by Kay (2006) and therefore is not considered further here.
7.3 Enforcement of buffer zones
Several countries have indicated they will now either develop a legal requirement for coastal buffer zones, or enforce pre-existing legislation that demarcates coastal buffer zones.
From a policy perspective, how successful will these legislative initiatives be? In Indonesia, where a coastal green belt buffer zone has been a legal requirement for more than a decade, there is no evidence that the law has been enforced anywhere in the archipelago. What changes will the future bring?
Obviously, if a buffer zone is to be a reality anywhere in the coastal zones of the eight affected countries, then it will require more effort than the proclamation of a new law in most cases.
In an assessment of the top-down approach to managing forest resources, Enters et al. (2003) concluded that generally, policies developed in a top-down and elitist manner are less effective than policies that have been formulated with meaningful input from all interested and affected parties. By restricting stakeholder involvement in policy formulation and review, and relying on forestry experts alone, forest policies said all the right things and read very well on paper, but were difficult to implement. The forest policies received no support from other forestry stakeholders or backing from other economic sectors with which forest policies frequently conflict. In some countries, policy reviews and development processes were also externally driven, often through donors, which led to policies that even forestry agencies did not agree with.
7.4 Resource taxes and their allocation
At least some of the ecosystem services provided by mangrove forests are taxed. For example, fish landed at markets are typically taxed and therefore there is an opportunity to assess the components of fisheries landings that comprise fish, shrimps, crabs and molluscs that are dependent on mangroves. From these data the amount of tax levied on mangrove-dependent species could be determined; then it is possible to pay these funds to the smallholders who maintain mangrove forests on their lands.
We have discussed the problems associated with determining the exact linkages between a specific stand of mangroves and the productivity of coastal fisheries for species that have linkages to mangroves. However, it is possible to identify relatively easily the majority of species that do have clear linkages to mangroves (Dudley, 2000); if this was done for landings at a national level within each country and the total area of mangroves was mapped, then a rough calculation of the per unit area of mangroves in general could be determined and the amount accruing to an individual smallholder with a finite area of mangroves could also be assessed.
Would this value be of sufficient benefit to alter decision-making at the farm household level?
For fisheries values alone, probably not, but if other ecosystem values were also included, such as coastal protection, channel maintenance and so forth, it might tip the scales in favor of retention of mangrove habitat in coastal areas.
7.5 Extension services
French (1995) suggested that emphasis should be placed on matching extension strategies with the decision-making needs of the farm household, and considered that in many development programmes traditional extension is not stimulating development to a significant extent; this is a serious flaw because extension services are expensive. He concluded that the old, top-down technology-driven extension model will not work any longer.
He contended that traditional government extension services are only suitable for a given period of development or under specific sets of conditions. This tends to be in the relatively early stages where government-induced programmes are needed to meet national objectives such as food security or import substitution. Once a reasonable proportion of the rural community has moved from subsistence agriculture to a market-driven economy, then governments can gradually invest less in traditional extension and the private sector plays a greater role (French, 1995).
Traditional extension services also appear to significantly ignore the pivotal role of women in food security (Garrity, 2006), who own only a small fraction of the world’s farmland and receive only a fraction (less than ten percent) of agricultural extension services.
Extension systems must become more flexible in their approaches (Place and Prudencio, 2006) as farmers are increasingly demanding information on market opportunities and processing techniques in addition to their typical production questions. Extension agents must therefore develop and maintain much larger information networks and with adequate resources to access the information and then transmit it to clients.
Farmers also demand different levels of service provision, from simple message transmission to more sustained technical support. To improve land management, it is necessary to promote knowledge-intensive practices such as integrated nutrient management as well as more simple transmission of information on output prices in different markets (Place and Prudencio, 2006).
Some signs of this are occurring, for example participatory rural appraisal (PRA) is becoming mainstream, but financial resources are often the binding constraints. There have also been attempts to reduce national governments’ share of costs and to move towards a fee-for-service system, but the feasibility of this for poor smallholder farmers is a major concern. How to implement these concepts in practice has remained mostly elusive (Place and Prudencio, 2006).
In at least some of the tsunami-affected countries there are many problems associated with the implementation of integrated coastal management plans — particularly plans that contain a clearly defined coastal green belt zone, which has been identified as a desirable objective.
Although there are considerable barriers today to the development of a plan that includes a satisfactory coastal green belt zone, there are no effective barriers to the possibility of setting targets for achievement of a coastal green belt over a longer period of time.
If the problem of what to do with the people and industries that currently occupy the green belt zone is considered intractable at present, it might still be possible to work steadily towards establishing an adequate coastal green belt over time. Although the green belt legislation which already exists in some of the tsunami-affected countries does not specifically exclude people from inhabiting green belt areas, the presence of settlements within green belt areas is not desirable because of unregulated activities and population growth. A workable green belt solution may have to recognize that some settlements will be permitted, but only if the growth of urban development within and between these settlements does not effectively remove the economic and security benefits of the green belt.
There are many mechanisms that could be employed to develop effective green belts over the longer term, but first a conscious, collective decision needs to be made by governments. This is a worthwhile goal to be achieved.
If a government decided that some 85 percent of the coastline should have a green belt by the end of a 15-year period, then it can begin today by examining which areas are already green belts and protect them now from conversion into other land uses.
Each year more areas could then be added to the green belts through a variety of mechanisms. With a long enough time horizon, this could be done with a minimum of dislocation and hardship. But it requires the will to stick to a plan and the discipline to ensure all stakeholders have the necessary incentives for cooperation.
8.1 A unique opportunity in Aceh
Another opportunity that should be mentioned is that large areas of the coastline in Aceh were washed away; consequently the coastal plain is no longer as wide as it used to be in many places, but at many of these sites the coastline is returning through a process of onshore transport of sediment by the sea.
Therefore, in these accreting areas it may be possible to actually grow the green belt seaward with the accreting coastline. This would require long-term planning commitment and also knowledge of which areas are accreting and how rapidly.
Prior to the tsunami, coastal management in the majority of the affected countries was not well coordinated and there is some evidence that the impact of the tsunami was greater than might have been the case if a more integrated approach to coastal management had been adopted.
There appears to be a conflict between the need for a well-defined and maintained coastal buffer zone or green belt comprising coastal forest and mangrove species, and the needs of access to these coastal zone habitats for other land-use purposes.
This paper contends that the major problem is not incompatibility of land uses, but a lack of integration of land uses owing to lack of knowledge, technical capacity and a regulatory framework.
A variety of integrated land management systems could be developed that provide benefits at a variety of levels, such as the regional scale with systems that integrate agriculture and aquaculture into the landscape with a focus on achieving harmony with other surrounding land uses through the mechanism of zoning.
At the small landholder level there are many integrated agroforestry and silvofishery systems that could deliver both better standards of living and a coastal green belt zone; these systems could be developed in all of the affected coastal zones.
Integrated coastal land use within each of the eight tsunami-affected countries can therefore be achieved and is highly desirable, not only because of the benefits which flow from a sustainable and effective coastal buffer zone or green belt, but also because of the beneficial impact on many small landholders, for whom the current land-use systems deliver marginal benefits at best.
However, simple proclamations of a coastal buffer zone will not suffice; what is required is an examination of why farm households and communities are consistently making decisions that lead to degradation and loss of coastal forest and mangroves.
Once the processes that drive the current deforestation are understood, it will be possible to construct alternative processes that lead to the establishment and maintenance of coastal green belt zones.
However, this will require both innovative and site-specific initiatives across a range of issues by government to put on track the long-term planning framework that will lead to a better managed coastal zone in the eight tsunami-affected countries.
Bibliography
Ahmad, T. & M. Mangampa. 2003. The use of mangrove stands for bioremediation in a closed shrimp culture system. In: D.J. Macintosh, M.J. Phillips, R.R. Lewis III & B. Clough, eds. (2002). Annexes to the thematic review on coastal wetland habitats and shrimp aquaculture. Case studies 1–6, pp. 47–54. Report prepared under the World Bank, NACA, WWF and FAO Consortium Program on Shrimp Farming and the Environment. Work in progress for public discussion. Published by the Consortium.
Ariyadasa, K.P. 2002. Assessment of tree resources in the home gardens of Sri Lanka. EC-FAO partnership programme (2000–2002) Tropical Forestry Budget Line B7-6201/1B/98/0531. Project GCP/RAS/173/EC, Bangkok, FAO.
Baker, K. 2000. Indigenous land management in West Africa: An environmental balancing act. Oxford Geographical and Environmental Studies. Oxford, Oxford University Press.
Barbier, E.B. & I. Strand. 1998. Valuing mangrove-fishery linkages: a case study of Campeche, Mexico. Environmental and Resource Economics, 12 (2): 151–166.
Barbier, E.B., Strand, I. & S. Sathirathai. 2002. Do open access conditions affect the valuation of an externality? Estimating the welfare effects of mangrove-fishery linkages in Thailand. Environmental and Resource Economics, 21: 343–267.
Bhattarai, T.N. 1995. Integration of wood energy in agroforestry extension programmes in Southeast Asia. Appendix A. In: Regional Wood Energy Development Programme in Asia &Asia-Pacific Agroforestry Network summary report of training workshop on Integrating Woodfuel Production into Agroforestry Extension Programmes in Southeast Asia, 23–30 April 1995, West Java, Indonesia.
Bhattarai, T.N., Heruela, C., Hulscher, W. & A. Koopmans. 1997. Regional study on wood energy today and tomorrow in Asia. Field Document No. 50. Regional Wood Energy Development Programme in Asia. Bangkok, FAO.
Budisarsono, S., Wijaya, K. & J. Roshetko. 2006. Farm and household economic study of Kecamatan Nanggung, Kabupaten Bogor, Indonesia: A socio-economic base line study of agroforestry innovations and livelihood enhancement. ICRAF Working Paper No.19: 1–53.
Clough, B., Johnston, D., Xuan, T.T., Phillips, M.J., Pednekar, S.S., Thien, N.K., Dan, T.H. & P.L. Thong. 2002. Silvofishery farming systems in Ca Mau Province, Vietnam. Report prepared under the World Bank, NACA, WWF and FAO Consortium Program on Shrimp Farming and the Environment. Work in progress for public discussion. Published by the Consortium. 70 pp.
Davie, J. & E. Sumardja. 1997. The mangroves of East Java: an analysis of the impact of pond aquaculture on biodiversity and coastal ecological processes. Tropical Biology, 4(1):1–33.
Dudley, R. 2000. Technical note on the value of the fishery associated with Segara Anakan Lagoon. SACDP Report to Asian Development Bank.
Enters, T., Qiang, M. & R.N. Leslie. 2003 (eds). An overview of forest policies in Asia. EC-FAO Partnership Programme (2000–2002). Tropical Forestry Budget Line B7-6201/1B/98/0531. Project GCP/RAS/173/EC. Bangkok, FAO.
FAO. 2006. Global forest resources assessment 2005. FAO Forestry Paper No. 147. Rome, FAO. 348 pp.
Franzel, S., Denning, G.L., Lillesø-Barnekow, J.-P. & A.R. Mercado Jr. 2006. Scaling up the impact of agroforestry: Lessons from three sites in Africa and Asia. Chapter 7. In: D. Garrity, A. Okono, M. Grayson & S. Parrott, eds. World agroforestry into the future. Nairobi, World Agroforestry Centre.
French, J.H. 1995. Farm household decision making and extension framework for understanding farm household-level decision making and design of agroforestry extension strategies. Appendix B. In: Regional Wood Energy Development Programme in Asia & Asia-Pacific Agroforestry Network summary report of Training Workshop on Integrating Woodfuel Production into Agroforestry Extension Programmes in SouthEast Asia, 23–30 April 1995, West Java, Indonesia.
Gammage, S. 1997. Estimating the returns to mangrove conversion: sustainable management or short term gain? Environmental Economics Programme, International Institute for Environment and Development. DP97-02.
Garrity, D. 2006. Science-based agroforestry and the achievement of the Millennium Development Goals. Chapter 1. In: D. Garrity, A. Okono, M. Grayson & S. Parrott, eds. World agroforestry into the future. Nairobi, World Agroforestry Centre.
Garrity, D., Okono, A., Grayson, M. & S. Parrott. 2006. (eds.) World agroforestry into the future. Nairobi, World Agroforestry Centre.
Hiraishi, T. 2005. Tsunami risk and countermeasure in Asia and Pacific area: Applicability of greenbelt tsunami prevention in the Asia and Pacific region. Japan, Port and Airport Research Institute.
Hanley, J.R. 2006. Technical guidelines for reforestation of mangroves and coastal forest in Aceh province. Report to FAO. 55 pp.
Hanley, J.R. & D. Hariyanto. 2000. The development of a mangrove management model for Segara Anakan Lagoon. Segara Anakan Conservation and Development Project (SACDP) Package 2 – components B and C. Community Development and Project Management and Capacity Building Components. BCEOM French Consulting Group in association with PT. Ardes Perdana and PT. Bhawana Prasasta. 60 pp.
Harakunarak, A. & S. Aksornkoae. 2005. Life-saving belts: post-tsunami reassessment of mangrove ecosystem values and management in Thailand. In: Tropical coasts, pp. 48–55.
Inoue, Y., Hadiyati, O., Afwan Affendi, H.M., Sudarma, K.R. & I.N. Budiana. 1999. Sustainable management models for mangrove forests (models based on feasibility studies of management cases in Republic of Indonesia. The Development of Sustainable Mangrove Forest Management Project, the Ministry of Forestry and Estate Crops in Indonesia and Japan International Cooperation Agency.
Jensen, M. 1995a. Species selection and woodfuel production in agroforestry. Appendix E. In: Regional Wood Energy Development Programme in Asia & Asia-Pacific Agroforestry Network summary report of Training Workshop on Integrating Woodfuel Production into Agroforestry Extension Programmes in Southeast Asia, 23–30 April 1995, West Java, Indonesia.
Jensen, M. 1995b. Woodfuel productivity of agroforestry systems in Asia: A review of current knowledge. Field Document No. 45. Regional Wood Energy Development Programme in Asia GCP/RAS/154/NET. Bangkok, FAO.
Kay, R. 2006. Integrated coastal zone planning in Asian tsunami-affected countries. FAO workshop on coastal area planning and management in Asian tsunami-affected countries, 27–29 September 2006, Bangkok, Thailand.
Kathiresan, K. & N. Rajendran. 2005. Coastal mangrove forests mitigated tsunami. Estuarine, Coastal and Shelf Science, 65: 601–606.
Kerr, A.M., Baird, A.H. & S.J. Campbell. 2006. Comments on “Coastal mangrove forests mitigated tsunami” by K. Kathiresan & N. Rajendran. Estuarine, Coastal and Shelf Science 67: 539–541.
Lewis, R.R. III, Phillips, M.J., Clough, B. & D.J. Macintosh. 2003. Thematic review on coastal wetland habitats and shrimp aquaculture. Report prepared under the World Bank, NACA, WWF and FAO Consortium Program on Shrimp Farming and the Environment. Work in progress for public discussion. Published by the Consortium. 81 pp.
Manson, F.J., Loneragan, N.R., Skilleter, G.A. & S.R. Phinn. 2005. An evaluation of the evidence for linkages between mangroves and fisheries: A synthesis of the literature and identification of research directions. Oceanography and Marine Biology: An Annual Review, 43: 483–513.
Marshall, E., Schreckenberg, K. & A.C. Newton. (eds) 2006. Commercialization of non-timber forest products: factors influencing success. Lessons learned from Mexico and Bolivia and policy implications for decision-makers. Cambridge, UK, UNEP World Conservation Monitoring Centre.
Mazda, Y., Magi, M., Kogo, M. & N.H. Phan. 1997. Mangroves as coastal protection from waves in Tong King Delta, Vietnam. Mangroves and Saltmarshes, 1: 127-135.
Phillips, M.J. & A. Budiman. 2005. An assessment of the impacts of the 26th December 2004 earthquake and tsunami on aquaculture in the provinces of NAD province and North Sumatra, Indonesia. FAO. 144 pp.
Pauly, D. & J. Ingles. 1986. The Relationship between shrimp yields and intertidal vegetation areas: a reassessment. In: A. Yañez-Arancibia A. and D. Pauly, eds IOC/FAO Workshop on Recruitment in Tropical Coastal Demersal Communities. IOC Workshop Report 44 - supplement.
Phillips, M. & A. Budiman. 2005. An assessment of the impacts of the 26th December 2004 earthquake and tsunami on aquaculture in the provinces of NAD province and North Sumatra, Indonesia. FAO, 144 pp.
Place, F. & Y.C. Prudencio. 2006. Policies for improved land management in smallholder agriculture: The role for research in agroforestry and natural resource management. Chapter 8. In D. Garrity, A. Okono, M. Grayson & S. Parrott, eds. World agroforestry into the future. Nairobi, World Agroforestry Centre.
Primavera, J.H. 1995. Mangroves and brackishwater pond culture in the Philippines. Hydrobiologia, 295: 303–309.
Primavera, J.H. 1997. Socioeconomic impacts of shrimp culture. Aquaculture Research, 28: 815–827.
Primavera, J.H. 1998. Mangroves as nurseries: shrimp populations in mangrove and non-mangrove habitats. Estuarine, Coastal and Shelf Science, 46: 457–464.
Primavera, J.H. 2000. Integrated mangrove-aquaculture systems in Asia. Integrated Coastal Zone Management. Autumn edition, 121–130.
Roshetko, J.M., Lasco, R.D. & M.S. Delos Angeles. 2006. Smallholder agroforestry systems for carbon storage. In: Mitigation and adaptation strategies for global climate change. Springer.
Sadio, S. & P. Negreros-Castillo. 2006. Trees outside forests: facing smallholder challenges. Chapter 21. In: D. Garrity, A. Okono, M. Grayson and S. Parrott, eds. World agroforestry into the future. Nairobi, World Agroforestry Centre.
Saenger, P. 2002. Mangrove ecology, silviculture and conservation. Dordrecht, Kluwer Academic Publishers.
Saenger, P. & S.C. Snedaker. 1993. Pantropical trends in mangrove above-ground biomass and annual litterfall. Oecologia, 96:293–299.
Samarakoon, J. 2006. Land tenure and use change in relation to poverty and the environment in Asian tsunami-affected countries. FAO Workshop on Coastal Area Planning and Management in Asian Tsunami-affected Countries, 27–29 September 2006, Bangkok, Thailand.
Sathirathai, S. & E.B. Barbier. 2001. Valuing mangrove conservation in Southern Thailand. Contemporary Economic Policy, 19 (2):109–122.
Scherr, S. & P. Hazell, P. 1994. Sustainable agricultural development strategies in fragile lands. Environmental and Production Technology Development Division Discussion Paper No. 1. Washington, DC, International Food Policy Research Institute.
Scialabba, N. (ed) 1998. Integrated coastal area management and agriculture, forestry and fisheries. FAO guidelines. Environment and Natural Resources Service. Rome, FAO. 256 pp.
Spaninks, F. & P. van Beukering. 1997. Economic valuation of mangrove ecosystems: potential and limitations. Collaborative Research in the Economics of Environment and Development (CREED). Working Paper No. 14.
Suyanto. 2006. Impact analysis of HKm (Hutan Kemaysarakatan) on livelihoods and land management in Sumberjaya. In: M. van Noordwijk & T. O’Connor, eds. Highlights of ongoing research of the World Agroforestry Centre in Indonesia. ICRAF Southeast Asia Working Paper 2006 No. 1. pp. 73–77.
Tookwinas, S., Songsangjinda, P., Na-anan, P., Matsuda, O. & U. Ekpanithanpong. 2003. An integrated physical and biological process for treatment of marine shrimp farm effluent. In: D.J. Macintosh, M.J. Phillips, R.R. Lewis III & B. Clough, eds. 2002. Annexes to the: Thematic Review on Coastal Wetland Habitats and Shrimp Aquaculture. Case studies 1–6. Report prepared under the World Bank, NACA, WWF and FAO Consortium Program on Shrimp Farming and the Environment. Work in progress for public discussion. Published by the Consortium. pp. 47–54.
Tuán, V.A., Clough, B., Lu, T., Johnston, D., Phillips, M.J. & P. Chanratchakool. 1999. Mixed shrimp-mangrove farming practices: a manual for farmers. ACIAR – MOFI Project FIS/94/12 "Mixed Shrimp Farming-Mangrove Forestry Models in the Mekong Delta".
Upton, M. 1996. The economics of tropical farming systems. Cambridge, Cambridge University Press.
van Noordwijk, M. 2006. Equipping integrated natural resource managers for healthy agroforestry landscapes. ICRAF Southeast Asia Working Paper, No. 2006_15
Wells, S., Ravilous, C. & E. Corcoran. 2006. In the front line: shoreline protection and other ecosystem services from mangroves and coral reefs. Cambridge, UK, United Nations Environment Program World Conservation Monitoring Centre. 33 pp.
Wolanski, E. 2006. Protective functions of coastal forests and trees against natural hazards. In: Coastal protection in the aftermath of the Indian Ocean tsunami: what role for forests and trees? 28–31 August 2006, Khao Lak, Thailand. Bangkok, FAO.
1Executive Marine Scientist, Sinclair Knight Merz, Perth, Australia.
2 Bangladesh, India, Indonesia, Malaysia, the Maldives, Myanmar, Sri Lanka and Thailand.
19US$1.00 = IDR9 077 (February 2007).
