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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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