The investigation took place in an area of 2 km² toward the interior of a dry plain of quarzitic sands on the Floristic Managed Reservation San Ubaldo-Sabanalamar; to carry out the study they were located six parallel, lineal transepts of 100 m of long for 1 of wide. Was carried out a general list of the flora; in accordance with the habit, the species were determined as nurses and is estimated their covering according with the transept line method, besides calculating the distance in the land

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... hat separate each one them, are identified the species that are under the canopy of nurses and also those that occupy the empty spaces among them, counting the number of individuals for species to calculate the frequency and abundance of them, which are the plants that better recruit other species (best nurses), as well as a group of interesting associations for future studies. A floristic inventory was obtained ,was visible that the specific richness of species under the nurses was significantly superior to the empty spaces; through other analyses, was demonstrated that the species that cohabit there were not related phylogenetically, those results prove that relationships of facilitation exist between plants as well as the importance of the nurse effect in typical interactions in extreme environments, information that could be vital for restoring those degraded ecosystems with proven difficulties for the conservation ex situ of their species.