Introduction
Maintenance of biodiversity is the key to successful and sustainable conservation of mangrove habitats. The significance of biodiversity and its conservation in the field of environmental management and sustainable development have become a critical issue. Biodiversity contributes to many aspects of the ecosystem that are fundamental to human survival. At the very least, biodiversity provides the resources humans need to survive; for example, food, water, shelter, and medicine. Ecosystem stability and sustainability are also driven by biodiversity. Many aspects of ecosystem function such as biomass production, use of available resources, resistance to environmental stress and invasion and recovery from natural disasters are related to biodiversity. High biodiversity generally increases the stability of these processes, an important factor in the unpredictable and often rapidly changing mangrove environment. The complexity of mangrove ecosystems and high level of biodiversity increases their functional and utilitarian values to mankind. Influence and direct use of mangrove resources by local human populations are strong stimulants to the conversion of mangrove habitats. At the same time, these resources have great potential for sustainable management and rehabilitation.
Mangroves are salt-tolerant plant communities which are found in intertidal areas throughout the tropic and subtropic zones. These are found in approximately 123 countries (FAO, 2007) and are known to support a vast variety of animal and fish species. They also support terrestrial animals either directly or indirectly through the structural complexity of mangrove forests. Whether the fine roots, trunks, branches, leaves, or the surrounding substratum, each of these components offers a habitat for some animal species. For example, in mangroves of northwestern Australia at least 41 species of fish are known to reside in the interstitial spaces among the prop roots, while another 73 species use the fringing seagrass and associated cockle shell banks as their primary habitat (Hemminga and Duarte, 2000). This rich and unique biodiversity is supported by the complex, productive and stable tropical and subtropical ecosystems in the mangrove areas. However, despite these significant ecosystem functions, mangroves remain one of the most threatened ecosystems in the world (FAO, 2007).
Definition of Mangroves
Incorporating various definitions, mangrove can be regarded as generally a plant association in tropical and sub-tropical intertidal regions which is dominated by such species as various kinds of trees and shrubs which have adapted themselves to the saline conditions of the sea or the brackish water of the estuaries. A more comprehensive and useful concept of mangrove is given by the Forest Research Institute Malaysia: “Mangroves are ecosystems dominated by semi-terrestrial species that are unusually well-adapted to intertidal conditions of low oxygen and extended period of inundation (Burken et al., 1997). These are seen along sheltered tropical shores, estuaries, bays, and lagoons — that they have been able to colonize the intertidal area between the land and sea”. The last definition can be considered good enough, since it covers the basic characteristics of mangroves. The most important feature of the mangrove ecosystem, as agreed, is the trees and shrubs which grow in the intertidal zone. That is the role that we simply view a mangrove as a form of plant growth. An enhancement to all these definitions, mangrove can be viewed as a group of plants or plant communities and the areas inhabited by them, influenced by the high salinity water in the tropical and subtropical areas. Any further and all-inclusive definitions are thus far not needed.
Significance of Biodiversity Conservation
Biodiversity conservation is a key principle that can help the world to persist. Conservation of biodiversity is essential for the restoration of a strong ecosystem and for medical knowledge. With biodiversity, we can obtain many materials that directly and indirectly support our lives. The more than 7 billion human population living on Earth definitely needs a good quality of life, which includes food, water, shelter, and a healthy environment. Due to the large population, humans need a lot of resources to support their lives. The need for more resources can lead to the exploitation of natural resources, which is the biggest threat to biodiversity. Natural resources are obtained from ecosystems, but both will not survive if the resources are overused. In a short time, natural resources will be depleted, and both the ecosystem and humans will suffer. The ecosystem will be destroyed, and humans will lose their resources. Humans will then have to find the same resources in another place. This condition makes it possible for the previously found resources to be exchanged for other resources, leading to long-term exchanges. To avoid the exploitation of natural resources, we need alternative resources, resource efficiency, and responsibility for the environment through sustainable development. By doing all of this, we can save the key elements of biodiversity. It is recommended that biodiversity conservation be done as soon as possible, as the changes to the ecosystem may become harder to restore.
Role of Mangroves in Biodiversity Conservation
Mangroves support a plethora of species, providing food and nesting sites for a variety of birds and habitat for many marine and terrestrial animals such as the endangered dugong and the proboscis monkey. The intricate root systems of mangroves provide an attractive home for young fish from a range of species, including snappers, tarpon, and barracudas, as well as shrimps and crabs. Here, in the protective nursery of the mangroves, the fish find plentiful food and relative safety from larger predators. Many of these fish are commercially important and are the primary target of valuable fishing industries. Fish and crustaceans from mangroves are sources of food and income for humans. In addition, mangrove woods are themselves important to commercial and subsistence activities in many regions. Local people use the strong, hard wood for construction and crafts, and gather mangrove leaves, bark, and fruit as fodder for livestock. Honey and wax are products of mangrove flowers and bees that forage on the nectar, and tannins from mangrove bark are used in leather production. This reliance on mangroves means that people too have much to lose if the mangrove environment deteriorates, and sustainable use of mangrove resources could be an important step in their conservation.
Habitat for Various Species
Mangroves offer shelter amid the roots, trunks, and understory of trees to an extensive variety of creatures, including warm-blooded creatures, birds, reptiles, amphibious creatures, and various types of insects, mollusks, and nematodes. Specific species are expected to vary depending on different environmental conditions found in different mangrove forests located at different latitudes, as species’ suitability to specific conditions will vary. Mangrove fauna are also divided into two main groups: those who are solely dependent on the conditions provided by the mangrove, and those which use it as an extension of their habitat, colonizing the mangrove during certain stages in their life cycles. Migratory aquatic life, such as various species of crab, prawns, slipper and spiny lobsters, and some types of fish, are organisms that are primarily dependent on mangrove ecosystems. Mangroves represent one of the most amazing examples of evolutionary adaptation to changing environmental conditions. Four species of vertebrates and some amphibious creatures that are well adapted to life in the mangroves occur in Australia. Mudskippers and mangrove rivulus are physically adapted for living in the intertidal zones between air and water. Mammalian diversity in mangrove forests is generally low, with only four species of otter found in Asia and South America, together with the West Indian and Antillean manatees. It is not known whether the two species of manatees are critically dependent on mangroves during feeding or whether it is a case of mangrove destruction on seagrass beds affecting manatee populations.
Protection against Coastal Erosion
Mangroves act as a form of soft engineering in the coastal zone, meaning that typically man-made or natural habitations aim to control erosion by using external devices such as sea walls, piers, or groynes that can often have negative effects on the natural environment. The intricate root systems of mangroves dissipate wave energy and provide a buffer zone for upland habitats against tropical storms and hurricanes, and also act to reduce damage caused by tsunamis. In areas where mangroves have been cleared and the need for a natural defense against the sea is apparent, there have been attempts to plant mangroves in efforts to regain the protection and stability given by the natural environment. Coastal erosion can also occur as a gradual process where the loss of sediment leads to a lower beach profile and increased exposure to coastal environments. In this case also, mangroves have the potential to offer a long-term solution to the problem. A study in the Florida Keys compared erosion rates between areas dominated by mangroves and areas that had been cleared for development. The results clearly showed that the areas termed as “mangrove shorelines” had higher accretion and lower erosion rates than “cleared shorelines.”
Carbon Sequestration and Climate Regulation
Carbon (C) is stored in living biomass and soils and is cycled through photosynthesis, respiration, and through geologic processes. In nearshore ecosystems, such as seagrasses, saltmarshes, and mangroves, production of organic matter below and above ground, and its subsequent burial, is a significant process in the global carbon cycle. The amount of carbon that is sequestered and the amount of time it is stored is a function of the productivity of the vegetation and the physical conditions under which the organic matter is preserved. Peat accumulation is the long-term storage of carbon. Global calculations of carbon sequestration in mangroves vary, but are estimated at approximately 218 g C/m2/year in above-ground biomass, 75 g C/m2/year in below-ground biomass, and 72 g C/m2/year in sediment. This negative pressure may result in an increased input of organic matter to the sediment, acting as a positive feedback cycle to offset increased atmospheric CO2. Global climate regulation will inevitably have significant effects on the world’s mangroves and their sustainability. Changes to sea level, temperature, and precipitation will have direct effects on the distribution and growth of mangrove ecosystems and the maintenance of their soil carbon sinks. A reduction in suitable growing conditions for mangroves will result in the release of sequestered CO2 back to the atmosphere and a decreased capability to act as a carbon sink.
Importance of Awareness on Mangroves
Educating communities about the benefits of mangroves can be an effective, but often challenging, way to attempt to change public perception and government policy concerning mangroves. The objective is that informed communities will be better stewards of their natural resources and will be more likely to encourage government policy for sustainable mangrove management. This education can take place through a variety of media, including school programs, brochures, and even mangrove ecotourism. An understanding of the benefits of ecotourism on mangrove management will be an important part of this section. It is clear that unsustainable tourism adds to the list of direct anthropological threats to mangroves. However, if managed responsibly, ecotourism can be a useful tool for educating communities about the values of mangroves, and it can provide an economic alternative to the conversion of mangrove areas to agriculture or aquaculture.
Mangroves are not as noticeable to the public as coral reefs and sea grass beds, but that does not mean they are any less important. The understanding of the intricate relationship between the plant, animal, and physical components of the mangrove ecosystem, and the value of this ecosystem to human societies are crucial to the decision-making progress which results in effective and sustainable management practices. The less awareness there is about the value of the mangrove ecosystem, the more likely there will be continued large-scale removal of mangroves for pond construction, and the more likely the remaining mangroves will be harvested unsustainably.
Understanding the Value of Mangroves
Mangroves are an important ecosystem in a marine environment, serving as a link between land and sea and providing an area where terrestrial and marine organisms interact. These areas are home to a great deal of biodiversity and serve as nurseries for a wide array of marine organisms. Many commercial fish and crustaceans, including most of the species important for the fishery and reef areas, utilize the sheltered environment of the mangroves at some stage in their development. By acting as a buffer zone between open water and coastal lands, mangroves help to protect coastlines from damaging effects of hurricanes and tsunamis. The intricate root systems of mangroves also trap sediments and debris flowing down rivers, preventing it from reaching the sea. In addition to protecting the sea floor, this helps to clarify the water and remove pollutants. This root system helps to stabilize the coastline, lessening erosion from storm surges, currents, waves, and tides. It is estimated that one half of the world’s mangroves have been lost within the last half century, which translates to a loss of a hectare of mangrove every 6 minutes. Given the extensive benefits to humans and the environment, this speaks very poorly for the future. To help prevent further loss, it is essential to understand and spread knowledge of these benefits.
Educating Communities on the Benefits of Mangroves
Mangroves are ecosystems in the tropical and subtropical regions that provide productive habitats for a variety of organisms. They are woody plants (shrubs to trees) that grow at the interface between land and sea in tropical and subtropical areas as far north as the 30° N latitude and as far south as the 40° S latitude. These areas are often flooded by tides, but can also be subject to high freshwater inputs, depending on the locale. Because of these highly variable environmental conditions, mangrove roots are variously specialized to cope with the lack of oxygen in waterlogged mud. Various colonial powers were quick to see the benefits of mangroves. Dutch colonists in the East Indies set up timber concessions in the mangroves, while the British exploited them in Malaya. From 1910 to 1940, foreign companies cut about half of the total area of mangrove forest in the British Empire, mostly for firewood to be used by ships and trains. Logs were harvested for construction and tannin extraction, but overharvesting often led to the collapse of the industry as seen in the islands of Fiji. Today, the vast majority of mangrove timber in Southeast Asia is converted into charcoal. This colonial era was a great period of deforestation and one of the factors contributing to the slow recovery of mangroves today.
Promoting Sustainable Practices and Responsible Tourism
Sustainable utilization of a resource, in this instance the mangrove, is defined as the use of the resource in such a manner that it continues to provide a source of benefit in the long-term. This is applicable to all aspects of mangrove use whether it is for direct/indirect harvesting, conversion of the area and even the use of the area for research. The knowledge and findings gained from this project will provide the foundation for sustainable practices of mangrove use in the future. Through the education and influencing of key decision makers and local communities, the aim is to have this knowledge applied to promote a healthier status of the world’s mangroves and to prevent any further loss of this valuable resource. In doing so, the project will have been successful in providing a long-term benefit for mangrove conservation.
Promoting sustainable practices and responsible tourism among local communities, the private sector, and visitors is vital in ensuring the protection and conservation of mangroves. The mere advocacy of conservation vis-à-vis the exploitation of this rich ecosystem is insufficient; viable alternatives must be provided to all stakeholders. This would incur the need for an in-depth study of carrying capacity of specific sites and an economic evaluation of the benefits derived from the mangrove as opposed to those gained through its conversion.
Impact of Plantation Drives in Conserving Biodiversity
Regarding the impact of plantation drives in conserving biodiversity, Sabah’s experience shows that mangrove plantation has considerably enhanced biodiversity. This is achieved mainly through the selection of appropriate sites for plantation. High biodiversity value of a site is an important consideration in site selection for plantation. In general, only a small portion of degraded areas is selected for plantation, especially in areas where the natural regeneration process has been slow. Most sites are located near areas with good remaining natural vegetation in order that natural succession from the planted mangroves would support the existing adjacent natural community. An example is the Limau-Limauan Wildlife Sanctuary which has old growth mangroves and links to primary forest reserves. An exclosure experiment carried out at the sanctuary has shown that a 200m strip of degraded mangroves is able to recover its natural vegetation within 5-7 years through natural succession processes. This is a good indication for the success of future plantings in the sanctuary vicinity. In Sepanggar Bay and Kuala Abai in Kota Belud, the selection of degraded sites located near large well-preserved mangrove areas resulted in very rapid recolonization of macrofauna and good bird utilization of the planted areas. In particular, Kuala Abai, a site planted over 10 years ago, has been attracting a troop of proboscis monkeys from an adjacent mangrove reserve to feed within the planted area during low tides.
Restoring Degraded Mangrove Areas
Plantation drives represent a ray of hope for restoring degraded mangrove areas. New methods for mangrove forest management and rehabilitation are being tried in several countries, involving the planting of appropriate species in degraded areas to restore or improve forest structure and function. These efforts have met with varying levels of success so far, and in many cases the underlying ecological principles are not fully understood. Nonetheless, there is great potential to learn from these experiences and improve future rehabilitation efforts, helping to reduce the gap between the supply and the demand for goods and services provided by mangrove ecosystems.
Mangrove forests face a variety of threats. The degradation caused by the clearing of mangrove areas for commercial shrimp ponds, then abandoned or converted to other uses, is a common and widespread problem. Some areas are degraded through the removal of selected species for wood. Mangroves are also threatened by clearance for coastal construction and tourism developments, often as a result of the increasing pressure for housing, hotels, and other infrastructure to support growing coastal populations.
Enhancing Biodiversity through Plantation Efforts
Propagation and transplantation of mangrove species have the potential of greatly enhancing biodiversity. Often times, the same species of mangroves that are replanted are not the same species that were removed. This is due to limited availability of propagules and environmental conditions which may no longer be suitable for certain species. However, as more research is conducted on methods of mangrove reforestation, more diverse species of mangroves will be planted in order to restore a more natural community. This is significant considering that many areas containing degraded mangroves are typically only replanted with one or two species.
Biodiversity is an essential component of ecosystem productivity and social development. Mangrove forests are very productive ecosystems and serve as an essential nursery habitat for both marine and terrestrial organisms, including commercially important fish and shellfish species, migratory birds, and endangered species. The rich supplies of nutrients, the shelter provided by prop roots and vegetation, and the variety of habitats support an abundance of organisms.
Engaging Local Communities in Plantation Initiatives
Plantation drives and restoration efforts for mangroves are typically contained within a specific targeted area, usually one that has been identified as being heavily degraded and in need of specific action to avoid a specific disaster. However, attempts to restore areas that have been degraded for a long time are often hampered by lack of suitable understanding over the actual causes and effects of degradation. This can be an obstacle in the case of mangrove restoration since there is often a time lag between cessation of the original cause of degradation (e.g. pollution, aquaculture) and the start of restoration as the area is left fallow and it is usually initiated by a different generation of people. In such cases, the local community may contribute to ongoing degradation, or even if not, they may be unaware of the value of the ecosystem and the importance of restoration. Attempting to restore an area with a community that is hostile or one that is likely to repeat the mistakes of the past is a potentially futile exercise. It is essential in these cases to involve the local community in the restoration process and one of the most effectual ways of achieving this is through active participation in plantation drives.