12.2 Roadside tree barriers and dust movement

The selection of species will determine plant spacing, that is, the distance between the different shrubs and trees. Shrubs, for instance, grow at a much closer spacing than trees, which should be taken into account when determining the combination of species to be planted. The general guidance for row plantings is that larger trees are planted 3–5 meters apart, larger shrubs 2.5–4.0 meters apart, and smaller shrubs 1.5–2.5 meters apart. Single-row plantings should only be used on higher-value land and where space is limited. When possible, it is preferable to have plantings of two to four rows to protect a larger area. one- and two-row plantings are cost-effective options but require a uniform and high survival rate. figure 12.2 illustrates different types of roadside plantings. Porous barriers have the most beneficial impact on dust control. Dust capture is enhanced by

FIGURE 12.2

Roadside tree barriers and dust movement