Sunday, 13 January 2013

Deforestation & Its Social Impacts

by Divya Sharma

Much of what we have been learning about in this course is related to the collaboration between tropical field biology and genomics. Once we got to the Galeta Marine Lab, however, we were given a new topic of discussion: the interaction between social and ecological issues and, specifically, the role of deforestation.

Our first talk was given to us by Wayne Sousa, who spoke to us about the threats facing mangrove forests. These are forests that dominate low energy shorelines in the tropics and low latitude subtropics, in areas of high salinity. Mangrove forests are important ecosystems, in that they provide a habitat for many non-marine species, some of which are endangered, as well as a nursery habitat for edible fish and crustaceans. They protect against wind, flooding and storm surges. They moderate air temperature, stabilise shorelines and reduce erosion. They store carbon, and they trap terrestrial sediments and pollutants, thereby protecting coral reefs. They are also important economically, used for timber, charcoal and fisheries in Panama.

And yet, despite all these ecosystem services that they provide, mangrove forests are in decline worldwide. It is estimated that over 50% of the original global cover of mangroves has been lost, due to coastal development, clear-cutting, shrimp farming, mining, pollution and sea level rise. In Galeta, a large swath of mangrove forest was cleared to make way for a ship container yard, which was never even used. The subsequent negative effects of deforestation on drainage led to part of the surrounding forest being destroyed as well. One of the most obvious effects of mangrove habitat loss is the flooding of roads after rains in Galeta.

Our second talk was given by Nicole Gottdenker, who spoke about how deforestation impacts the ecology of Chagas disease. This illness is transmitted by blood-sucking bugs, and is a major cause of heart disease in Latin America. In her presentation, she explained how 83% of the Earth’s surface is under direct human influence, the ecological consequences of which are habitat fragmentation, pollution, changes in biogeochemical cycles, and more. In Panama, there have been high rates of deforestation in the past 40 years, in order to clear land for agriculture. About 73% of deforested land is due to pasture extension, which is often then converted into peri-urban developments and coconut plantations. Chagas disease has been described as a disease of poverty, because its transmission is facilitated by substandard housing. Bugs enter in through cracks, screenless windows, thatched roofs and adobe walls. It is believed that human encroachment on the forest has increased risk of transmission. Specifically, the Palma Real (royal palm) is key to the transmission of Chagas disease; it is found in areas of high human activity, as it is often left standing when the surrounding forest is removed, possibly because it is hard to cut and because its leaves are used for thatching. The crown of the Palma Real houses an entire insect community as well as birds, mammals and reptiles. The kissing bug is one such insect that transmits the disease to mammals and then to humans. Nicole’s team found that their hypothesis was correct: there is increased vector infection in fragmented forest landscapes.

So here we saw two examples of the social effects of deforestation: a loss of major ecosystem services, including a buffer against climate change and protection from flooding; and increased infection of Chagas disease. From these cases, as well as from others, it is clear that ecological and social issues are intertwined in complex ways. One cannot consider one issue without the other. Deforestation cannot be limited solely through the use of scientific arguments, but must involve an acknowledgement of social, economic and political issues. Interdisciplinary studies and collaboration between different fields are clearly necessary for the cooperation of locals and for concrete changes to occur.

Path through a mangrove forest in Galeta

Mangrove forest on the Caribbean coast

A palm tree where mangroves once stood