The arroyo oak, Quercus brandegeei, is an endangered, narrowly endemic oak tree in Baja California Sur, Mexico. One-third of its 3,000 km2 range is within a protected area, Sierra La Laguna Biosphere Reserve. The region is a biodiversity hotspot with high levels of endemism and great beauty. In this case, however, simply protecting the species’ range does not address the threats causing the decline.

Since 2016, we have collected genetic, phenological, and ecological data on Q. brandegeei to determine specific threats and identify conservation and management actions needed to save it from extinction. We established fenced exclosures to quantify the effect of grazing and trampling by free-roaming livestock on seedling survival and growth.

Overall, our data suggest that climate change, habitat degradation, and overgrazing by cattle are likely affecting populations and preventing regeneration. Based on this information, we have developed a scientifically informed integrated conservation and management plan for this species that takes into consideration the socio-economic needs of local communities. We are currently working with Mexican scientists, land managers, ranchers, and international experts to implement this plan and save this culturally and ecologically important oak species.

Expected outcomes of this project include: 

(1) seedlings established in the wild for the first time in a century 

(2) acquisition of knowledge about factor(s) limiting regeneration of Q. brandegeei in the wild (3) estimates of future range under climate change and identification of sites suitable for assisted migration 

(4) scientifically robust germination and propagation protocols

(5) reintroduction and population reinforcement guidelines created and shared with stakeholders engaged in in situ conservation and management of Q. brandegeei 

(6) increased local capacity for conservation in the form of training and resources 

(7) increased representation of Q. brandegeei in botanic garden ex situ conservation collections

(8) peer-reviewed journal article(s), policy briefs, and educational materials

For more information, see The Global Tree Conservation Program.