Forests are defined by the FAO Forestry Department as `all vegetation formations with a minimum of 10 percent crown cover of trees and/or bamboo with a minimum height of 5 m and generally associated with wild flora, fauna and natural soil conditions'. In many countries, coastal areas such as beaches, dunes, swamps and wildlands - even when they are not covered with trees - are officially designated as `forested' lands and thus fall under the management responsibility of the Forestry Department or similar agency.
Forest resources (including wildlife) of coastal areas are frequently so different from their inland counterparts as to require different and special forms of management and conservation approaches. Mangroves and tidal forests for example have no parallels in terrestrial uplands. As a result, the information, policy and management requirements concerning integrated coastal area management (ICAM) for forestry are also different.
In each of the climatic regions of the world, inland forests and woodlands may extend to the sea and thus form part of the coastal area. In addition to such formations, controlled by climatic factors, special forest communities, primarily controlled by edaphic factors and an extreme water regime, are found in coastal areas and along inland rivers. Such forest communities include: mangroves, beach forests, peat swamps, periodic swamps (tidal and flood plain forests), permanent freshwater swamps and riparian forests. Of these, the first three types are confined to the coastal area, whereas the remaining types can also be found further inland.
Mangroves are the most typical forest formations of sheltered coastlines in the tropics and subtropics. They consist of trees and bushes growing below the high water level of spring tides. Their root systems are regularly inundated with saline water, although it may be diluted by freshwater surface runoff. The term `mangrove' is applied to both the ecosystem as such and to individual trees and shrubs.
Precise data on global mangrove resources are scarce. Estimates are that there are some 16 million ha of mangrove forests worldwide (FAO, 1994a). The general distribution of mangroves corresponds to that of tropical forests, but extends further north and south of the equator, sometimes beyond the tropics, although in a reduced form, for instance in warm temperate climates in South Africa and New Zealand to the south and in Japan to the north.
Mangrove forests are characterized by a very low floristic diversity compared with most inland forests in the tropics. This is because few plants can tolerate and flourish in saline mud and withstand frequent inundation by sea water.
There are two distinct biogeographic zones of mangroves in the world: those of West Africa, the Caribbean and America; and those on the east coast of Africa, Madagascar and the Indo-Pacific region. While the first contain only ten tree species, mangroves of the Indo-Pacific are richer, containing some 40 tree species (excluding palms).
Most of the animal species found in mangroves also occur in other environments, such as beaches, rivers, freshwater swamps or in other forest formations near water. On the whole, animal species strictly confined to mangroves are very few (crabs have a maximum number of species in mangroves). In many countries however, the mangroves represent the last refuge for a number of rare and endangered animals such as the proboscis monkey (Nasalis larvatus) in Borneo, the royal Bengal tiger (Panthera tigris) and the spotted deer (Axix axis) in the Sundarbans mangroves in the Bay of Bengal, manatees (Trichechus spp.) and dugongs (Dugong dugon). Mangroves are also an ideal sanctuary for birds, some of which are migratory. According to Saenger et al. (1983), the total list of mangrove bird species in each of the main biogeographical regions include from 150 to 250 species. Worldwide, 65 of these are listed as endangered or vulnerable, including for instance the milky stork (Mycteria cinerea), which lives in the rivers of mangroves.
This type of forest is in general found above the high-tide mark on sandy soil and may merge into agricultural land or upland forest.
Sand dune and beach vegetations are mostly scrub-like with a high presence of stunted tree growths. These coastal forest ecosystems are adapted to growing conditions that are often difficult as a result of edaphic1 or climatic extremes (strong winds, salinity, lack or excess of humidity). They are very sensitive to modifications of the ecosystem. A slight change in the groundwater level for example might eliminate the existing scrub vegetation. Sand dune and beach vegetations have an important role in land stabilization and thus prevent the silting up of coastal lagoons and rivers, as well as protecting human settlements further inland from moving sand dunes.
The dominant animal species on the adjacent beaches are crabs and molluscs. The beaches are also very important as breeding sites for sea turtles and, therefore, attract predators of turtles' eggs, such as monitor lizards (Varanus sp.).
This is a forest formation defined more on its special habitat than on structure and physiognomy. Peat swamp forests are particularly extensive in parts of Sumatra, Malaysia, Borneo and New Guinea, where they were formed as the sea level rose at the end of the last glacial period about 18 000 years ago. Domed peat swamps can be up to 20 km long and the peat may reach 13 m in thickness in the most developed domes. Animals found in peat swamps include leaf-eating monkeys such as the proboscis monkey and the langurs found in Borneo.
As with peat swamp forests, these are defined mainly by habitat and contain a diverse assemblage of forest types periodically flooded by river water (daily, monthly or seasonally). Periodic swamps can be further subdivided into tidal and flood plain forests.
Tidal forests are found on somewhat higher elevations than mangroves (although the term is sometimes used to describe mangroves as well). Such forests are influenced by the tidal movements and may be flooded by fresh or slightly brackish water twice a day. Tidal amplitude varies from place to place. Where the amplitude is high, the area subject to periodic tidal flushing is large and usually gives rise to a wide range of ecological sites. The natural vegetation in tidal forests is more diverse than that of mangroves, although still not as diverse as that of dense inland forests.
Flood plains are areas seasonally flooded by fresh water, as a result of rainwater rather than tidal movements. Forests are the natural vegetation cover of riverine flood plains, except where a permanent high water-table prevents tree growth.
The Amazon, which has annual floods but which is also influenced by tides to some 600 km inland, has very extensive permanent and periodic swamp forests. The alluvial plains of Asia once carried extensive periodic swamp forests, but few now remain as these have mostly been cleared for wetland rice cultivation. The Zaire basin is about one-third occupied by periodic swamp forests, many disturbed by human interventions, and little-studied (Whitmore, 1990).
Throughout the world, flood plains are recognized as being among the most productive ecosystems with abundant and species-rich wildlife.
The term is here used for permanent freshwater swamp forests. As opposed to periodic swamps, the forest floor of these is constantly wet and, in contrast to peat swamps, this forest type is characterized by its eutrophic (organomineral) richer plant species and fairly high pH (6.0 or more) (Whitmore, 1990).
Also called riverine or gallery forests. These are found adjacent to or near rivers. In the tropics, riparian forests are characterized as being extremely dense and productive, and have large numbers of climbing plants.
In addition to their aesthetic and recreational values, riparian forests are important in preserving water quality and controlling erosion and as wildlife refuges especially for amphibians and reptiles, beavers, otters and hippopotamus. Monkeys and other tree-dwelling mammals and birds are often abundant in riparian forests.
Other coastal forest ecosystems include: savannah woodlands, dry forests, lowland rain forests, temperate and boreal forests and forest plantations. Many of the natural coastal forests are under severe threat. Most of the lowland rain forests have vanished as a result of the ease with which commercial trees, standing on slopes facing the sea or other accessible coastal waters, could be harvested merely by cutting them down and letting them fall into the nearby water. As a consequence, most coastal dry forests and savannah woodlands have been seriously degraded by overexploitation for fuelwood and construction poles, and conversion to agriculture or to grazing lands through the practice of repeated burning.
Coastal plantations have often been established for both production and protection purposes. As an example of the latter, coastal plantations were established in Denmark as far back as the 1830s to stabilize sand dunes which were moving inland and which had already covered several villages.
The total economic value of coastal forests stems from use values (direct uses, indirect uses and option values) and non-use values (existence and bequest values).2 Table C.1 gives examples of the different values as related to coastal forests. Table C.4 gives examples of valuation approaches applicable to the various types of forest products or services.
|Use values||Use values||Use values||Non-use values|
|Direct uses||Indirect uses||Option values||Existence and bequest values|
|Timber||Nutrient cycling (including detritus for aquatic food web)||Premium to preserve future direct and indirect uses (e.g. future drugs, genes for plant breeding, new technology complement)||Forests as objects of intrinsic value, or as a responsibility (stewardship)|
|Non-timber forest products (including fish and shellfish)||Watershed protection||Endangered species|
|Recreation||Coastal protection||Charismatic species|
|Nature tourism||Air and water pollution reduction||Threatened or rare habitats/ecosystems|
|Genetic resources||Microclimate function||Cherished landscapes|
|Education and research||Carbon store||Cultural heritage|
|Human habitat||Wildlife habitat (including birds and aquatic species)|
Source: adapted from Pearce, 1991.
Direct use values, in particular the commercial value of timber and other forest products, often dominate land-use decisions. The wider social and environmental values are often neglected, partly as a result of the difficulty in obtaining an objective estimate of these, even though in many cases these values exceed the value of traded and untraded forest products.
Indirect use values correspond to `ecological functions' and are at times referred to as environmental services. Some of these occur off-site, i.e. they are economic externalities and are therefore likely to be ignored when forest management decisions are made.
The option existence and bequest values are typically high for coastal forests - especially for tropical rain forests or forests containing endangered or charismatic animal species.
In addition to the activities carried out within the coastal forests (see below), small- and large-scale forest industries are also often found in coastal areas, taking advantage of the supply of raw materials and the ease of transport by waterways and roads, the existence of ports for export, etc. In addition to sawmills and pulp and paper mills, these forest industries may include veneer and particle board factories, charcoal kilns (particularly near mangrove areas), furniture makers and commercial handicraft producers.
There is little information available on the value of marketed goods from coastal forests. In general, their contribution to national gross domestic product (GDP) is small and this fact may lead to their being neglected. Commercial wood production from coastal forests ranges from timber, poles and posts to fuelwood, charcoal and tannin. Non-wood products include thatch, fruits, nuts, honey, wildlife, fish, fodder and medicinal plants. A list of forest-based products obtainable from mangroves is shown in Box C.1.
Products obtainable from mangroves
A. Mangrove forest products
|Food, drugs and beverages
to preserve leather and tobacco
Paper - various
B. Other natural products
Source: adapted from FAO, 1984a.
Accounts of government forest revenues are often a poor indication of the value of the forest products. As an example, in 1982/83, in the Sundarbans mangroves of Bangladesh, some of the royalties collected by the forestry department were exceedingly low: for sundri (Heritiera fomes) fuelwood for instance, the market rate was nearly 40 times the royalty rate; and for shrimps the minimum market rate to royalty rate ratio at the time was 136:1 (FAO, 1994a).
Frequently, the value of untraded production (e.g. traditional fishing, hunting and gathering) in mangrove forest areas is substantial, the value often exceeding that from cultivated crops and from formal-sector wage income (Ruitenbeek, 1992).
Other direct use values of the coastal forests include their social functions. Coastal forests provide habitat, subsistence and livelihood, to forest dwellers, thereby supplying the means to hold these communities together, as well as opportunities for education, scientific research, recreation and tourism. Worldwide, the lives of millions of people are closely tied to productive flood plains, the associated periodic river floods and subsequent recessions. The socio-economic importance of these areas is especially evident in the more arid regions of the developing world. The seasonal ebb and flood of river waters determines the lifestyles and agricultural practices of the rural communities depending on these ecosystems.
Examples of the educational value of coastal forests are found in peninsular Malaysia, where more than 7 000 schoolchildren annually visit the Kuala Selangor Nature Park, a mangrove area with boardwalk, education centre, etc. (MNS, 1991). In nearby Kuantan, along the Selangor river, a main tourist attraction are evening cruises on the river to watch the display of fireflies and, along the Kinabatangan river in Sabah, cruises are undertaken to watch the proboscis monkeys as they settle in for the night in the riparian forest.
In terms of employment opportunities in coastal forests, ESCAP (1987) estimated the probable direct employment offered by the Sundarbans mangrove forest in Bangladesh to be in the range of 500 000 to 600 000 people for at least half of the year, added to which the direct industrial employment generated through the exploitation of the forest resources alone equalled around 10 000 jobs.
A prominent environmental role of mangroves, tidal, flood plain and riparian forests is the production of leaf litter and detrital matter which is exported to lagoons and the near-shore coastal environment, where it enters the marine food web. Mangroves and flood plains in particular are highly productive ecosystems and the importance of mangrove areas as feeding, breeding and nursery grounds for numerous commercial fish and shellfish (including most commercial tropical shrimps) is well established (Heald and Odum, 1970; MacNae, 1974; Martosubroto and Naamin, 1977). Since many of these fish and shellfish are caught offshore, the value is not normally attributed to mangroves. However, over 30 percent of the fisheries of peninsular Malaysia (about 200 000 tonnes) are reported to have some association with the mangrove ecosystem. Coastal forests also provide a valuable physical habitat for a variety of wildlife species, many of them endangered.3
Shoreline forests are recognized as a buffer against the actions of wind, waves and water currents. In Viet Nam, mangroves are planted in front of dykes situated along rivers, estuaries and lagoons under tidal influence, as a protection measure (L┐yche, 1991). Where mangroves have been removed, expensive coastal defences may be needed to protect the agricultural resource base. In arid zones, sand dune fixation is an important function of coastal forests, benefiting agricultural and residential hinterland.
In addition, mangrove forests act as a sediment trap for upland runoff sediments, thus protecting sea grass beds, near-shore reefs and shipping lanes from siltation, and reducing water turbidity. They also function as nutrient sinks and filter some types of pollutants.
The option value of coastal forests - the premium people would be prepared to pay to preserve an area for future use by themselves and/or by others, including future generations - may be expected to be positive in the case of most forests and other natural ecosystems where the future demand is certain and the supply, in many cases, is not.
An example of how mangrove values are estimated is given in Box C.2.
Net present value of mangrove forestry and fisheries in Fiji
Using data on the amounts of wood and fish actually obtained from mangrove areas and their market value and harvesting costs, the net present value (NPV) of forestry and fisheries were estimated for three mangrove areas in Fiji, using the incomes or productivity approach with a 5 percent social discount rate and a 50-year planning horizon.
Forestry net benefits
Commercial net benefits were calculated as wood harvested multiplied by market value, minus harvesting costs.
Subsistence net benefits were calculated using the actual amount of wood harvested multiplied by the shadow value in the form of the price for inland or mangrove fuelwood sold by licensed wood concessionaires.
Taking the species composition of the mangrove area into account, the weighted average NPV was estimated for each of the three main mangrove areas yielding the following:
NPV: US$164 to $217 per hectare.
Fisheries net benefits
In only one of the three areas was the fisheries potential judged to be fully utilized and the data are based on this area.
Annual catch (commercial and subsistence): 3 026 tonnes. Area of mangroves: 9 136 ha, thus averaging 331 kg per hectare, equalling $864 per hectare in market value annually.
By taking harvesting costs into account, the following result was obtained:
NPV: $5 468 per hectare, or approx. $300 per hectare per year.
This is assuming a proportionate decline in the fisheries. With only a 50 percent decline (as some of the fish are not entirely dependent on the mangroves) the figure for the NPV is $2 734 per hectare.
The value of mangroves for nutrient filtering has been estimated, using the alternative cost or shadow project method, by Green (1983), who compared the costs of a conventional waste water treatment plant with the use of oxidation ponds covering 32 ha of mangroves. An average annual benefit of $5 820 per hectare was obtained. This figure is, however, only valid for small areas of mangroves and, as it represents the average, not the marginal value, it should be treated with caution.
The option value and the existence value of mangroves are not captured using the above incomes approach and an attempt to include these values was made by using the compensation approach, as the loss of fishing rights in Fiji caused by the reclamation of mangroves has been compensated by the developers. The recompense sum is determined by an independent arbitrator within a non-market institution. Large variations in recompense sums were however recorded ($49 to $4 458 per hectare) according to the end use and the bargaining power of the owner of the fishing rights. Using 1986 prices the following results were obtained:
Average: $30 per hectare for non-industrial use and $60 per hectare for industrial use.
Maximum: $3 211 per hectare.
By adding the benefits foregone in forestry and fisheries, it can be concluded that the minimum NPV of the mangroves of Fiji is $3 000 per hectare under present supply and demand and existing market and institutional organizations.
Source: Lal, 1990.
The term coastal forests covers a wide range of different ecosystems many of which can still be classified as natural ecosystems, although - particularly in the temperate region - they may have been modified through human interventions over the years. However, they still generally contain a greater biological diversity (at genetic, species and/or ecosystem levels) than most agricultural land.
The most important characteristics of coastal forests are probably their very strong links and interdependence with other terrestrial and marine ecosystems.
Mangroves exemplify such links, existing at the interface of sea and land, and relying, as do tidal and flood plain forests, on fresh water and nutrients supplied by upland rivers to a much larger extent than more commonly found inland forest types. Figure C.1 illustrates the mangrove-marine food web.
Source: CV-CIRRD, 1993.
In the arid tropics, there may be no permanent flow of fresh water to the sea, and the leaf litter and detritus brought to the marine ecosystem by tidal flushing of coastal mangrove areas, where these exist, is the only source of nutrients from the terrestrial zone during the dry season. This further magnifies the role of mangroves in the marine food web. In the Sudan, for example, such a role is considered to be a crucial function of the narrow mangrove fringe found along parts of the Red Sea coast (L┐yche-Wilkie, 1995).
As for the wildlife species found in coastal forests, most are dependent on other ecosystems as well. Mammals may move between different ecosystems on a daily or seasonal basis, water birds are often migratory, and many commercial shrimps and fish use the mangroves as spawning ground and nursery sites but move offshore in later stages of their life cycle. Anadromous species, such as salmon, spawn in freshwater rivers, but spend most of their life cycle in marine waters; catadromous species on the other hand, spawn at sea, but spend most of their life in freshwater rivers. These species probably thus pass through coastal forests at some point in their life.
A variety of natural or human-incurred risks and uncertainties affect the sustainable management of coastal forest resources. Some natural risks may be exacerbated by human activities. Uncertainty arises from: the natural variability inherent in coastal forest ecosystems; the incomplete knowledge of the functioning of complex natural ecosystems; the long time-frame needed in forest management; and the inability to predict accurately the future demands for goods and services provided by natural and cultivated forests.
Natural risks. These include strong winds, hurricanes and typhoons, floods (including tidal waves) and droughts, which can all cause considerable damage to coastal forests.
Global climate change caused by human actions may, through a rise in temperatures, result in `natural' risks such as a rise in sea level, changes in ocean currents, river runoff and sediment loads, and increases in the frequency and severity of floods, drought, storms and hurricanes/typhoons.
Human-incurred threats. Human-incurred threats to coastal forests stem mainly from the competition for land, water and forest resources. These include conversion of coastal forest to other uses, building of dams and flood control measures, unsustainable use of forest resources both within the coastal area and further upland, and pollution of air and water.
In many developing countries, deforestation continues to be significant; the annual loss of natural forests resulting from human pressures amounted to an estimated 13.7 million ha in the 1990 to 1995 period (FAO, 1997d). Human-incurred threats to forests are often more pronounced in coastal areas as a result of the relatively high population density of such areas caused by the availability of fertile soils, fishery resources and convenient trade links with other domestic and foreign markets.
Natural variability. One particular uncertainty faced by forest managers relates to the natural variability exhibited by the coastal forest and wildlife resources. Such natural variability can be found at two levels:
The above risks and uncertainty caused by incomplete knowledge are compounded by the long time-frame needed in forest and wildlife management. Trees, and some animals, need a long time to mature: 30 years for mangrove forests used for poles and charcoal; and 150 years for oak (Quercus) grown for timber in temperate forests. This long period between regeneration and harvesting makes the selection of management objectives more difficult because of further uncertainty regarding future market preferences for specific forest and wildlife products or services, future market prices, labour costs, etc.
An important characteristic of natural ecosystems (including natural coastal forests) is that once a natural ecosystem has been significantly altered, through unsustainable levels or inappropriate methods of use, it may be impossible to restore it to its original state. Conversion of natural coastal forests to other uses is an extreme example.
It may be possible to replant mangrove trees in degraded areas or in abandoned shrimp ponds, but the resulting plantation will have far fewer plant and animal species than the original natural mangrove ecosystem.
Acid sulphate soils. A particular cause of concern with regard to irreversibility is the high pyrite (FeS2) content in many mangrove and tidal forest soils, which renders them particularly susceptible to soil acidification when subject to oxidation. This is probably the most acute problem faced by farmers and aquaculture pond operators when converting such forests and other wetlands to rice cultivation or aquaculture ponds, and it makes restoration of degraded areas almost impossible.
Reclamation of acid sulphate soils requires special procedures such as saltwater leaching alternating with drying out, or the establishment and maintenance of a perennially high, virtually constant groundwater-table, through a shallow, intensive drainage system. These may be technically difficult or economically unfeasible.
Coastal forests tend to be owned by the state. The inability of many state agencies in the tropics to enforce property rights, however, often means that a de facto open access regime exists, which frequently results in overexploitation of forest resources.4 This problem is only partly overcome by awarding concessions and usufructuary rights as these are often short-term in nature and not transferable and, therefore, fail to provide incentives for investments and prudent use of the resources.
Where the state agency has the ability to enforce laws and regulations and the government has a policy of promoting multipurpose management of state-owned forests, sustainable forest management can be achieved (Box C.3).
Mangrove stewardship agreement in the Philippines
One example of successful multipurpose management of a state-owned coastal forest using a participatory approach and aiming to restore the more traditional communal ownership of forests, is the issuing of `Mangrove Stewardship Agreements' in the Philippines. Local communities (or private individuals) obtain a 25-year usufruct lease over a given mangrove area with the right to cut trees selectively, establish new mangrove plantations and collect the fish and shellfish of the area based on a mutually agreed mangrove forest management plan. The Department of Environment and Natural Resources (DENR), which implements this scheme, will assist the local communities and individuals in preparing this management plan if needed. Local NGOs are also contracted by DENR to assist in the initial `Community Organizing' activities, which include an awareness campaign of the benefits obtainable from mangrove areas and an explanation of the steps involved in obtaining a Stewardship Agreement.
As a result of the variety of goods and services provided by coastal forests and their links with other ecosystems, a large number of institutions often have an interest in, and sometimes jurisdiction over parts of, the coastal forest ecosystems. This raises the risk of conflict between institutions, even within a single ministry.
The forestry department or its equivalent generally has jurisdiction over the coastal forest resources. However, the parks and wildlife department, where it exists, may have jurisdiction over the forest wildlife, and the fisheries department almost certainly has jurisdiction over the fisheries resources found in the rivers within coastal forests, and may regulate the use of mangrove areas for cage and pond culture. Other institutions with an interest in coastal forests include those related to tourism, land-use planning, mining, housing, ports and other infrastructure.
In many countries, there is often little public awareness of the variety of benefits provided by coastal forests, and campaigns should be conducted to overcome this. Mangroves and other swamp forests in particular have often been regarded as wastelands with little use except for conversion purposes. As a result of the low commercial value of wood products compared with the potential value of agriculture or shrimp production, conversion has often been justified, in the past, on the basis of a financial analysis of only the direct costs and benefits. Such analyses, however, do not take into account the value of the large number of unpriced environmental and social services provided by coastal forests, which in many cases far outweigh the value of any conversion scheme.5
The ecological links between coastal forests and other terrestrial and marine ecosystems and the institutional links between the forestry sector and other sectors, must be addressed through an area-based strategy that takes a holistic approach to sustainable development. An ICAM strategy provides the appropriate framework for such an approach.
The nature of coastal forests as described above calls for a precautionary approach6 to the management of their resources and the adoption of flexible strategies and management plans drawing on the knowledge of the local communities.
The precautionary principle can be incorporated into coastal forest management by imposing sustainability constraints on the utilization of coastal forest ecosystems. Other measures include environmental impact assessments, risk assessments, pilot projects and regular monitoring and evaluation of the effects of management. Research, in particular on the interdependence of coastal forests and other ecosystems and on the quantification and mitigation of negative impacts between sectors, is also needed.
Environmental impact assessments7 should be undertaken prior to conversions or other activities that may have a significant negative impact on coastal forest ecosystems. Such activities may arise within the forest (e.g. major tourism development) or in other sectors outside the forest (e.g. flood control measures). Where there is insufficient information on the impact of proposed management actions, applied research and/or pilot projects should be initiated.
Public participation in the management of coastal forest resources will increase the likelihood of success of any management plan and should be accompanied by long-term and secure tenure/usufruct.
1 See Glossary.
2 For a description of these concepts, see Part A, Box A.24.
3 See Section 1.1.
4 See Part A, Section 1.6.1 and Box A.2. Also Part E, Box E.7.
5 See Part A, Section 1.6.1 and Boxes A.22 and A.24.
6 See Part A, Section 1.6.3 and Boxes A.3 and A.5.
7 See Part A, Box A.6.