As popular as they are in contemporary landscapes, mulches are not a new concept. For as long as trees have grown in forests, leaves and needles have fallen to the ground, matted together, and formed a natural protective layer over the soil.
The use of mulches in landscape plantings provides many benefits. When water droplets land on bare soil, the impact causes soil particles to fly in all directions, resulting in soil crusting and slow water infiltration. Most mulches break the impact of the droplets, reducing soil erosion and crusting and increasing the penetration of water into the soil.
In addition, mulches improve soil structure in several ways. As organic mulches decompose, they provide organic matter that prompts soil particles to aggregate. Large aggregates increase aeration and improve moisture conditions in the soil. These conditions, in turn, encourage additional root development and biological activity, further enhancing soil structure.
Among the most desirable characteristics of bark mulches are their excellent resistance to compaction and blowing in the wind, their attractiveness, and their availability.