Habitats of Schinus patagonicus and Schinus marchandii in the Chilean Patagonia were studied, in order to determine the plant communities into these species growing and the primary or secondary character of them, to help establish the conservation status of the two species. We worked with phytosociological methods to characterize floristic and vegetationaly the communities. The vegetation table is ordered with traditional methods, using differential species and with multivariate statistical classification and ordination methods. The initial vegetation table provided 68 plant species of which 26 are introduced weed. In the biological spectrum dominated hemicryptophytes and minor phanerophytes and therophytes. Traditional management of the vegetation table separated the Mutisio-Schinetum patagonicae ("clavel del aire" and "molle" scrub) and Colliguajo-Schinetum marchandii ("duraznillo" and "laura" steppe scrub) new associations that are described. Comparison of these two communities established that they are floristically very different and that their phytosociological affinity is low, the first is a secondary scrub community that replaces the deciduous patagonic "lenga" forest and the "fire" scrub degraded by human action and the second, a primary steppe community. The abundant presence of Mulinum spinosum differentiates degraded stages of these two communities specially the first. The secondary character of the "clavel del aire" and "molle" community confirms the more aggressive and competitive position of Schinus patagonicus, which ensures their survival as a species, but the primary character and the small size of the scrub of "laura" and "duraznillo" scrub also areal reduction of Schinus marchandii indicate that the conservation status of the latter species in Chile is poor.