Role of forest in influencing the quality of – Air : (i) It helps in purifying the air by adding oxygen into it. (ii) It takes carbon-dioxide gas during photosynthesis thus green-house effect is controlled. (iii )Transpiration helps in the formation of clouds and thus, it maintains the temperature of surrounding area, giving cooling effect. Soil : (i) Plants in forest hold the soil. Thereby preventing soil erosion. (ii) It holds the soil which helps in increasing the underground water level. (iii) Adds nutrients to the soil due to lot of vegetation present in forest gets decomposed. Water : Forest helps in bringing rain and increasing the level of water in the underground and water bodies.