Forests cover 45 % of the islands. Rain forests exist on the windward sides of the mountainous islands, while the leeward sides have grassy plains. The islands suffer from a 0.21 % (1990-2000) annual rate of deforestation. The loss of trees has resulted in soil erosion, and silt washed into the ocean can smother coral. The siltation, combined with oil exploration, sewage dumping, and overfishing, threaten Fiji’s coral reefs as well as the coastal ecosystems. With its valuable plant and animal life and low population growth, the Fiji Islands’ environmental problems are not as severe as other places in the world.