User:Emmuschek/Mangrove restoration

Mangroves Across the World
Mangroves are typically found in tropical regions of the world on the coasts of America, Australia, Asia, and Africa. Mangrove ecosystems are found in about 120 countries in the world and make up 0.7% of the world's tropical forests. In most of these regions mangroves provide many services including; shelter, climate regulation through carbon sequestration, decrease coastal erosion, create a link between terrestrial and marine ecosystems, and maintain water quality along the coast. Mangroves have recently become susceptible to deforestation due to human activities and extreme weather. Aquaculture, agriculture, and urbanization are some of the reasons why mangroves are being damaged or destroyed.

Restoration Process
Mangroves are sensitive ecosystems, changing dynamically in response to storms, sediment blockage, and fluctuations in sea level  and present a "moving target" for restoration efforts. Mangroves are considered to be one of the easiest coastal systems to restore because of their seedlings ability to survive where adult trees are not present. The most common method simply consists in planting single-species stands of mangroves in areas thought to be suitable, without consideration of whether or not they supported mangroves in the past. This approach usually fails over the long term because the underlying soil and hydrological requirements of the mangroves are not being met. Mangrove survival is dependent on many factors including soil salinity, sedimentation, groundwater availability, and tidal changes which can vary greatly in small areas. This means, each tree in a mangrove forest will grow slightly different resulting from its unique surrounding conditions.

More informed methods aim to bring a damaged mangrove area back into its preexisting condition, taking into account not only ecosystem factors but also social, cultural and political perspectives. These approaches begin with the understanding that a damaged mangrove area may be able to repair itself through the natural processes of secondary succession, without being physically planted, provided that its tidal and freshwater hydrology is functioning normally and there is an adequate supply of seedlings. If natural renewal does occur, Twilley et al. 1996 predicts species composition will be largely determined by the very earliest saplings to colonize the recovering stand. This prediction is supported by the actual studies of Clarke et al. 2000, Clarke et al. 2001, Ross et al. 2006 and Sousa et al. 2007.

A second approach to mangrove restoration is the ecological mangrove restoration (EMR) approach. This approach mainly focuses on correcting the hydrology of a mangrove ecosystem for long lasting health of the area while the plantation approach does not truly take into account the dynamics of the ecosystem. While some planting may be required in the EMR approach, the expectation is that mangrove seedlings will be able to naturally recolonize. Steps to the EMR approach are as follows:


 * 1) Assess the ecology, especially reproduction and distribution patterns, of the mangrove species at the disturbed site;
 * 2) Map the topographical elevations and hydrological patterns that determine how seedlings should establish themselves at the site;
 * 3) Assess the changes made to the site that currently prevent the site from recovering by itself;
 * 4) Design a restoration plan that begins by restoring the normal range of elevations and tidal hydrology at the site; and
 * 5) Monitor the site to determine if the restoration has been successful in light of the original objectives.

This may include introducing structures such as detached breakwaters, to protect the site from wave action and allow for adequate sediment build-up. The actual planting of seedlings is a last resort, since it fails in many cases; it should be considered only if natural recruitment of seedlings fails to reach the restoration objective.