Factors determining the habitat of Drosera sessilifolia in the humid zone of the Brazilian Cerrado

摘要

Drosera sessilifolia, a tiny carnivorous plant whose adult size is around 3 cm, sometimes inhabits the humid zone known as the "campo limpo umido" in the Brazilian Cerrado region. D. sessilifolia rarely occurs in the swampy area along the stream in this region; however, its occurrence is expected to decline with agricultural development. In the present study, we examined the factors determining the habitat and growth of D. sessilifolia in the campo limpo umido as well as how these factors have been modified by agricultural developments. Our survey suggests that the growth of D. sessilifolia is greatly influenced by light in areas where sufficient soil moisture is available. The light environment at the edge of a track constructed for reasons of agricultural development is in fact more suitable for D. sessilifolia than that found in the areas formerly inhabited by it. However, soon after construction, the artificial habitat may be occupied by tall-growing plants. In the former habitat of D. sessilifolia, the amount of accumulated litter and the size of the submerged spot also influenced its growth. In order to conserve short-growing plants, like D. sessilifolia in the plant community, the accompanying tall-growing dominant grasses should be controlled by periodic human disturbance.