Abstract: Low -density species are species that occur with a low density of mature individuals. They are the most common species in tropical forests. Knowledge and protection of low density species are key tobiodiversity conservation in tropical forests. The meanings of low density species is broader than that of rare species. Low density species also include species that have low density, wide distribution range and a huge number of mature individuals. Low survivorship of seeds and seedlings near the parent individual is an important mechanism of creation of low density species. Low density species probably arise from intraspecific density dependent effects and limited population recruitment. The possible mechanisms of maintenance of low density species lie in both external factors, such as capacities of insect pollinating, and inner factors, including flower number and flowering duration of tropical plants. Some tropical species are self fertilized, compensating for the decline in opportunity for cross breeding due to extreme low density. Up to now, few studies have been carried out in this field. We should design more detailed research in combination with research on the properties of tropical forests, so that we can provide a theoretical basis and practical advice for biodiversity conservation in tropical forests of our country.

Key words: nature reserves, entomogenous fungi, ecological distribution, diversity