Caracterización del hábitat de Amoreuxia wrightii (Bixaceae), una especie en peligro de extinción en el noreste de México

Background and Aims:  In Mexico,  Amoreuxia wrightii  is endangered according to NOM-059-SEMARNAT-2010. In this study the characterization of natural populations of  A. wrightii,  which grow in two contrasting communities taking into account the canopy cover in the Tamaulipan thornscrub in northeastern Mexico, was performed by analysis of associated flora and physical and chemical properties of soils. Methods:  In 2014, 10 sampling sites were established in two environments differentiated by vegetation structure: five sites in plant associations with dense vegetation cover and five sites in disturbed areas with bare soil. In each area the vegetation structure and edaphic variables were evaluated and a Canonical Correspondence Analysis was performed. Key results:  According to the relationship with other species,  A. wrightii  was associated with pioneer species that emerge after disturbance, dominated by grasses like  Aristida purpurea, Cenchrus ciliaris ,  Cynodon dactylon, Panicum obtusum , herbs such as  Gutierrezia sarothrae ,  Gymnosperma glutinosum  and  Parthenium hysterophorus , and low shrubs like  Acacia amentacea ,  A. berlandieri  and  Eysenhardtia texana . According to edaphic variables, it was observed that  A. wrightii  preferred clayey and silty soils, soils with slightly alkaline pH and high bulk density. No individual of  A. wrightii  was recorded at sites that had soils with high sand content and high content of organic matter. Conclusions: Amoreuxia wrightii  was more abundant in areas with no coverage, devoid of vegetation, soils low in organic matter and high in pH, silt, clay and bulk density. According to the relationship with other species, it was associated with pioneer species, which emerge after a disturbance.