Natural Processes and Human Actuations: Impacts on Mangrove Forests of South America

The great importance of mangroves’ forest is linked to their capacity of resilience against natural and human impacts, this way playing a determinant function in the adaptation to climatic change related processes. At global scale, mangroves’ forests cover an area of 150,000 km2, 11% (≈16,500 km2) of them being located along the Pacific and Caribbean coasts of South America. About 70 species of mangroves exist around the World with 10 observed in South America, among them the most relevant are: Rhizophora mangle, Avicennia germinans, Laguncularia racemosa and Conocarpus erectus. Concerning mangroves’ cover loss, at global scale, an annual rate of 0.16% was observed between 2000 and 2012 with lower rates recorded in South America respect to Asia, Africa, North and Central America. This paper analyses the main effects of natural and human impacts on mangroves’ forests by means of examples from South America and several other countries. Concerning natural impacts special attention was devoted to: i) constant and ii) specific erosion processes (related to storms and tropical cyclones), both of them essentially affect Rizophora mangle since this specie occurs at the shoreline meanwhile strong winds recorded during hurricanes (with a category > 3 of the Saffir-Simpson scale) especially affects R. mangle and A. germinans, and iii) the effects of climatic phenomena such as “El Niño” and “La Niña” that produce variations in soil salinity that determinates the establishment and growth of a mangrove’s specie or an other. Concerning human impacts special attention was paid to illegal logging that, in the Northern Caribbean of Colombian coast essentially affectes L. racemosa, which wood is used by local population to build up cabins on the beaches for tourist purposes. Keywords: Coastal erosion, Hurricane, El Niño, Deforestation, Salinity.