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ECOLOGY
Mangroves are forests that border the sea and provide habitats for birds and aquatic species, as well as maintain the shoreline,preventing erosion and providing regular estuary waters. The mangrove systems are an important part of the Vietnamese ecosystem, but herbicidal use in the war devastated many of these plant communities. One application of herbicide devastated a mangrove and natural regeneration does not occur due to lack of seed source and because mangrove soil harbors herbicide that stunts any new growth. Destroyed mangroves have been replaced by new plant communities, as shown by the table below:
The consequences of mangrove loss include erosion of shoreline due to wave action, decreased fertility in mud flats, and turbid estuary waters which affects the rest of the ecosystem increasingly. Bird species found in mangroves have been found to have high extinction rates. In defoliated areas of the jungle, all insectivorous and frugivorous species are missing entirely except for barn swallows. Two rare species of the Mekong Delta are now extinct in Vietnam: the white shouldered ibis and the giant ibis. Aquatic species were also hurt by the devastation of forests
and mangroves. Fish are affected in three ways, including indirectly
via disrupted vegetation on adjacent land areas, toxicity of
herbicides on aquatic plants, zooplankton, and macro-invertebrates,
all of which are food sources for fish, and herbicides are toxic
to fish themselves. Soil has shown a long term decrease in productivity due to herbicidal spraying. Soil has been exposed to more heat and rainfall (due to lack of jungle cover) causing an overall loss of nutrients and growth. Topsoil has been washed away by heavy rainfall, and has a decreased capacity for water. This has resulted in severe flooding and erosion that devastates not only new growth but crops as well. (26)
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