The wolf is a nationally protected animal and acts as the guardian of order for grassland ecosystems. Wolves help to eliminate weak or sick animals and thus keep the numbers of herbivores at sustainable levels. As a result, wolves indirectly contribute to the health and quality of the grassland. Natural areas where wolves are present are free of dangerous infectious diseases among animals, and the grassland is not over-grazed. However in many areas of China, including Tibet, the wolf is often perceived as dangerous and is hunted and killed. This perception is gradually changing thanks to education efforts in recent years.