We find them useful because:
(i) Forests are biodiversity hotspots: 80% of the terrestrial species of plants and animals are found in forests. They provide shelter to wildlife.
(ii) Forests serve as a watershed: A watershed is a high piece of land that catches rainfall and other precipitation and divides the flow of water into streams, rivers, lakes, marshes, etc.
Forested watersheds is able to absorb more water, recharge aquifers, sustain stream flow, slow down the flow of water, filters the pollutants and also provide habitat for the aquatic animals.