Pinyon-juniper woodlands are one of the most extensive vegetation types in western North America and cover approximately 19 million ha. The American Southwest is characterized by extreme drought conditions accompanied by rising temperatures, causing widespread tree mortality in pinyon-juniper woodlands. This die-off occurred across 1.2 million hectares of the southwestern United States and killed up to 350 million pinyon pines. Widespread tree mortality is an indicator of climate change clearly visible not only to scientists, but also decision makers and the general public.
This research makes significant contributions to understanding mechanisms of tree mortality. Die-offs are significant events for humans and natural systems. Services to humans, biogeochemical cycling, energy fluxes, and wildlife habitat are among the processes severely affected.
The Colorado Plateau and Southern Great Plains continue to experience frequent droughts and high temperatures. On-going research examines whether even drought tolerant junipers may succumb to increased aridity and begin dying at increased rates, potentially significantly altering fire regimes.
These findings will help managers predict how forests will respond to warming and the impacts that will cascade through ecosystems, and provide a better understanding of how climate influences trees.