Summary
A survey on seedling nodulation of native leguminous forest species was made in an area near Manaus, Amazonas, Brazil, with typical humid tropical forest vegetation on yellow oxisols of varying textures. This survey was made by collecting seedling from the forest with intact root systems, registering the presence of nodules and the type of soil were the collection was made. Seedlings were transplanted to polyethylene bags with a horizon forest soil to verify if nodulation by native Rhizobium sp. occurs in nursery conditions. One year later observations were made for: presence of nodules, nitrogenase activity, as well as some nodule characteristics. Of the 34 species, 22 showed nodulation. Of these nine belonged to the subfamily Mimosoideae, six to Caesalpinioideae and four to Papilionoideae. Of these twelve were collected on sandy soils and six on clay soil and one in the two types of soil. Capacity of nodulation was observed in some species that were not reported in a recent revision as being able to nodulate before (Cedrelinga catenaeformis, Diplotropis purpurea and Tachigalia sp).