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 Environmental Impacts of Agent Orange in Vietnam

The loss of a significant proportion of southern Vietnam‘s forest cover triggered a number of related effects. For example, loss of timber led to reduced sustainability of ecosystems, decreases in the biodiversity of plants and animals, poorer soil quality, increased water contamination, heavier flooding and erosion, increased leaching of nutrients and reductions in their availability, invasions of less desirable plant species (primarily woody and herbaceous grasses), and possible alterations of both macro- and microclimates. – Wayne Dwernychuk, Hatfield Group.  

Even though Operation Ranch Hand ended nearly 40 years ago it has continued to have ongoing environmental impacts not only in Vietnam but in other areas around the world where the herbicides were used, stored and manufactured.  From Da Nang, Viet Nam to Gulfport, MS; from Midland, MI to New Brunswick, Canada. In Viet Nam, the impacts on the ecosystem are still visible, especially in the heavily sprayed mountainous regions along where the Ho Chi Minh trail was located. In addition, high levels of TCDD dioxin from the 2,4,5-T can still be found in the areas that were frequently sprayed, where the herbicides were stored and loaded onto planes, where large spills took place or where the manufacturing process resulted in dioxin leaching into the surrounding areas and transported downstream. 

South Viet Nam’s total land area was about 67,000 square miles or about the size of New England. During the time of the Vietnam War dipterocarp forests, plantations, mangroves, brush lands, and other woody vegetation covered around 39,000 square miles (25 million acres) of southern Viet Nam an area approximately the size of Vermont, New Hampshire and Massachusetts combined. The dense forests that covered the uplands of southern Viet Nam also provided cover for the enemy forces that the US military and their allies were trying to fight against.  For ten years the US Air Force flew nearly 20,000 herbicide spray missions in order to destroy the forest cover as well as agricultural lands in key areas of southern Viet Nam.  More than five million acres of forests and agricultural lands were sprayed at least once approximately 10% of total land area of southern Viet Nam and about 20% of the forest cover.  In addition the use of Rome Plows, to literally bulldoze down the forests and clearing along roadways resulted in the destruction of an area the size of Rhode Island.  

 Within two to three weeks of spraying the leaves would drop from the trees which would remain bare until the next rainy season. In order to defoliate the lower stories of forest cover one or more follow-up sprayings were needed.  About 10 percent of the trees sprayed died from a single spray run. Multiple sprayings resulted in increased mortality for the trees as did following the herbicide missions with napalm or bombing strikes. Extensive logging off of the defoliated trees also contributed to the destruction of vast areas of forests that may have regenerated if simply sprayed by herbicides.

The most sensitive trees were the mangroves in the Delta regions some of which only needed one spray run to become defoliated and eventually die. Approximately 259,000 acres of mangroves were sprayed, about one-third of the mangroves vital to the coastal ecology were damaged or destroyed.  Of the upland forests sprayed the hardest hit were the dense forests of Ma Da, Phu Binh, Sa Thay, A Luoi and along Route 19.  In addition, 15% of the spray runs, mainly using Agent Blue, were targeted against agricultural lands an attempt to deny the ‘enemy’ of food. However, civilian food sources were also damaged.

As a result of the herbicides hundreds of trees species were defoliated and died.  A minimum of 20 million cubic meters of timber was destroyed, though estimates range as high as 90 million if you take into consideration the additional impact of plows, bombing, napalm strikes and harvesting of defoliated trees. The destruction was so great that the terms “ecological warfare” and later ‘ecocide’ were coined to describe it.

In areas where deforestation and subsequent degradation of the forest occurred invasive species of grasses Pennisetum polystachyon and Imperata cylindrica that the Vietnamese call “American grass” took over. Natural regeneration of the forest cover lost was not possible as there were not enough trees to produce viable seedlings nor was there a layer of trees to protect the vulnerable seedlings from the harsh tropical sun.  Moreover, the defoliated lands unable to hold on to the soil during the heavy rains resulted in the depletion of soil nutrients and large scale erosion especially in the mountainous regions affecting 28 river basins in southern Viet Nam.  Even with intense reforestation it would take hundreds of years to bring these areas back to pre-war conditions.

The habitat of Southern white cheeked gibbons, the Eastern Sarus Cranes, tigers, Asian elephants, gaur, wild water buffalo, wild boar, bear, deer, civets, leopards and many other species of animals were heavily affected by the herbicides and the war in general. The two species that thrived as a result of the deforestation were rats and mice, previously rare to the forested areas after the war they were quite common, causing damage to crops and spreading diseases.

 The destruction of the habitat by the war compounded by post-war human activities threatened the extinction of many species that were already rare, and pushed others into the rare column especially as the remaining forest areas became under even more population pressure, were logged off and turned into plantations. In addition, previously sustainable practices such as swidden agriculture and harvesting of forest products were no longer viable in areas where severe defoliation occurred.

 After the war the Vietnamese government began reforestation efforts. Starting with the mangrove forests in the Mekong Delta regions and in Can Gio outside of Saigon areas where mangroves are vital in preventing serious flooding during the seasonal monsoons and tropical storms.  Fortunately these species are relatively easy to replant and today more than 190,000 acres of the mangroves have been replanted. Today the main threat to the coastal Mangroves is extensive shrimp farming operations.

 However restoring the diverse upland forest ecology has not been as easy as this requires intensive reforestation efforts including the harvesting of seeds from high quality hardwood trees, nurturing the seedlings in nurseries, replenishing the depleted soil, planting a layer of fast growing shade trees to protect the young seedlings and finally planting the hardwood seedlings that make the upper story and then the seedlings of species of trees, rattans, bamboos and shrubs that make up the lower stories.  The Ma Da forest north of Ho Chi Minh City (formerly Saigon) has in recent years undergone intensive reforestation efforts and Vietnamese scientists have found that as the habitat has been restored wildlife are returning to the area.

 For the most part, the Vietnamese have planted single species plantations of acacia and eucalyptus in the defoliated regions of the upland forests in order to stem erosion on the defoliated land and provide a renewable resource for the local populations. These trees are harvested every 4 – 5 years and sold for pulp or the furniture industry and provide an income for the local population. However, this is just a temporary measure, longer term plans if funding is available is to increase the quality and biodiversity of the forest coverage as much possible, taking into consideration both the conservation goals of the region as well as the human needs of sustainable use of forests.














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