The forests of Vietnam are a curious mix of the sublime and the simple. In spite of the deforestation rate and the chronic loss of primary forest each year (see Forests of Vietnam), the total area of forest cover in Vietnam has reportedly increased over the past two decades (but go here for a different assessment). This is largely due to reforestation activities and the creation of single-species plantations. The species most commonly planted in these plantations is Acacia mangium (shown above). You will drive by thousands of hectares of Acacia mangium as you travel through Vietnam.
This species propagates well, grows fast, protects the soil, and fixes nitrogen. There are a lot of reasons for planting it. Still, from an ecological standpoint, replacing some of the most biodiversity-rich forests in Southeast Asia with a single species of tree from northeastern Australia has its problems.