During the Vietnam War, natural ecosystems of Gio linh district, Quang Sinh province had been adversely impacted due to the military operations, especially herbicide use. Over the decades, the vestiges of herbicide still exist in the ecosystems of Gio Linh district. As a result, natural ecosystems of this region have been changed into grassland, secondary forests and plantation. The ecosystems, which were formed because of the impacts of herbicides, often have a simple structure and not even reached a stable status: Secondary forests with unstable vegetation branches and many vines
grasslands with simple structure shrub and mainly hard body grass. According to the ecological succession, the ability of recovery of plimary forest is highly possible in the transition zone between current secondary forests and grasslands, but with slow speed in current conditions. It is because several critical factors, which are not approprivate for natural forest to develope to stable status, are existing in the current destroying ecosystems. These critical factors include temperature-humidity regimes of air and soil and light level.