Assessing pinyon-juniper mortality across Southeast Utah Group National Parks

Pinyon-Juniper (PJ) communities that include woodlands, savannas, and closed canopy forests, cover an extensive area of 100 million acres across the western U.S. and are critically important for providing a wide range of resources for humans and habitat for plants and animals, including numerous endemic and imperiled species such as the pinyon jay (Hartsell et al. 2019). Despite their importance, pinyon and juniper trees have experienced recent dieback events due to drought, aridification, and insect outbreaks (Fig. 1). For example, the 2002 – 2003 drought that covered much of the southwestern U.S. resulted in widespread pinyon mortality (Breshears et al. 2005), and more recently the 2017 – 2018 drought caused juniper dieback on the Colorado Plateau (Campbell et al. 2020), including Southeastern Utah Group (SEUG) parks. We used funding from CNHA and protocols jointly developed by the USGS and NPS SEUG to assess tree structure and condition in the field, and then scaled up evaluation of dieback using aerial and satellite imagery across Arches and Canyonlands National Parks and Natural Bridges National Monument.