Assisted Migration 2024

Adapting to future climates - establishing Abies religiosa beyond its upper natural altitudinal limit
 

Dr. Cuauhtémoc Sáenz-Romero and team continued monitoring and evaluating seedling survival and growth performance of Abies religiosa (oyamel) planted in July 2021 at four altitudes (3400m, 3600m, 3800m and 4000m). This study is examining how the monarchs’ overwintering forest may adapt to a future warmer climate, shifting to higher elevations as temperatures increase. Three of the four test sites are above the current upper limit of the tree’s natural distribution of 3,550 meters. 

To compensate for an expected warming of 2.3°C, the forest would need to shift approximately 500 meters higher. On average, at that elevation there was a decrease in growth of only 36% and a decrease in survival of 21% to date, in comparison to an estimated growth and survival with no shifting. These results are encouraging and represent the possibility of healthy adapted trees at higher elevations under future climates. Dr. Sáenz-Romero points out that it is also important to remember that the “umbrella and blanket” protective effect that Abies religiosa provided to the overwintering monarch butterfly colonies requires that the Oyamel Fir forests consist of healthy trees, not weakened, defoliated trees, as climate change is causing today.

These experiments are helping us understand and plan for future climate conditions so that monarchs will continue to have healthy overwintering forests in the future! MBF is pleased to support this necessary research to improve conservation efforts in the face of climate change.
 

Publications on understanding forests of the future

In 2024, Dr. Sáenz-Romero and colleagues published two papers on their work to understand forests of the future. 

In April, Bryce Richardson, Gerald Rehfeldt, Cuauhtémoc Sáenz-Romero, and Elizabeth Milano published "A climate analog approach to evaluate seed transfer and vegetation transitions" in Frontiers in Forests and Global Change, Vol 7. MBF posted an article on this modeling work here. 

In September, Dr. Sáenz-Romero and colleagues published their findings on the assisted migration experiments after three full growing season. "Establishing monarch butterfly overwintering sites for future climates: Abies religiosa upper altitudinal limit expansion by assisted migration" in Frontiers in Forests and Global Change, Vol 7.  They conclude that "establishment of A. religiosa at 3600 and 3,800 m is feasible and that planted stands could eventually serve as overwintering sites for the Monarch butterfly under projected future climates."

To read more about Dr. Sáenz-Romero's Assisted Migration research conducted in previous years, please explore the links below.