Ecological Effects of Military Defoliation on the Forests of South Vietnam

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Abstract
The United States has defoliated over 2 million hectares or 20% of the forests of S. Vietnam between November 1961 and the present. The major agent used has been a 50:50 mixture of 2,4-D and 2,4,5-T, applied at 29 kilograms per hectare for a total of over 40 million kilograms. Some 35% of S. Vietnam's 5.5 million hectares of dense forest (jungle) have been sprayed one or more times (25% once, 10% more than once). The plant and animal communities have been altered and simplified (with a reduction in biomass); there has been a loss of nutrients, and a reduction in ecosystem productivity. Restoration time is expected to exceed one decade. In those 0.5 million hectares of multiply sprayed jungle, these effects have been more drastic, permitting significant amounts of conversion to Imperata grasslands or bamboo brakes whose reversion to forest is not expected for at least several decades. Over 20% of S. Vietnam's 0.5 million hectares of mangrove forest have been sprayed, causing total annihilation of the vegetative cover without subsequent recovery for a time measurable in decades. The plant and animal communities have been totally disrupted.