Out of the 3,554 km2 area of district, (29%) constitutes forest area. It may be denser or less dense. The northeast part of district has a vast forest area of . In this, is reserved forests and the rest is vested forests. Of these, 80% is deciduous whereas the rest is evergreen. The forest area is mainly concentrated in Nilambur subdistrict, which shares its boundary with the hilly district of Wayanad, Western Ghats, and the hilly areas (Nilgiris) of Tamil Nadu. Trees like teak, rosewood, and mahogany are seen in Nilambur forest area. Bamboo hills are widely seen in the forest. Karimpuzha wildlife sanctuary is the one and only wildlife sanctuary in the district and is also the largest wildlife sanctuary in Kerala. The New Amarambalam Reserved Forest, which is a part of the Karimpuzha Wildlife Sanctuary, has a variety of fauna. A variety of animals including elephants, deer, tigers, blue monkeys, bears, boars, rabbits, birds, and reptiles are found in forests. Forest products like honey, medicinal herbs, and spices are also collected from here. Forests are protected by two divisions- Nilambur north and Nilambur south. About 50 Acre of Mangroves forest is found in Vallikkunnu, located in coastal area of the district. A major part of Kadalundi Bird Sanctuary lies in district. Kadalundi-Vallikkunnu community reserve is the first community reserve in Kerala. It has now been declared as an eco-tourism centre. Tirunavaya is known for its lotus fields.