Ecological restoration and protection of remnants are key to the survival of the critically endangered Araucaria tree under climate change

Araucaria angustifolia - 'araucaria'- is a critically endangered conifer tree of great ecological, economic, and cultural importance occurring in subtropical forests and grasslands in southern Brazil. Using ecological niche modeling we estimated its distribution in the present and future scenarios (2050), assessed sources of uncertainties, evaluated the effectiveness of protected areas, and indicated suitable sites for restoration efforts to maintain viable populations. For this, we generated and compared 11,484 models with different combinations of variables and parameters. The final model included variables related to climate, soil, and topography. The potential distribution of araucaria was estimated to be 489.8 x 10 3km2, with a predicted reduction in 2050 from 45% to 56% (SSP245 and SSP585, respectively). The reduction within remaining habitats is estimated to range from 32% to 44%. Combined, current habitat availability and climate change accounted for a reduction from 70% to 75% of the potential distribution. Only 5% of the current potential distribution is within protected areas, which may be reduced to 1%. In addition, 40% of suitable sites in remaining habitats are not protected, which may reduce to 24-28% in 2050. Restoration efforts may contribute to an increase of 42-45% of the remaining population. We show that estimates of araucaria distribution in the future are variable and dependent on climate projections and scenarios, however, the potential distribution in natural grasslands may remain stable. Coordinated actions involving the protection and restoration of habitats associated with population growth are urgent to improve the persistence of araucaria in the future.