The Colorado Plateau is home to the largest stand of ponderosa pine trees in the world. They dominate upland watersheds and are a crucial provider of ecosystem services, including contributing to clean water supplies, providing wildlife habitat and wood products, as well as storing a lot of carbon.
But ponderosa pine mortality has been unusually high across the Four Corners region since the mid-1980’s, when between 11 and 18% of pines died from drought-associated wildfires and bark beetle infestations.
Regeneration has been slow – often due to a lack of seed trees. So, Professor Tom Kolb and grad student Aalap Dixit at Northern Arizona University’s School of Forestry are collaborating with researchers from state universities in Utah and New Mexico to investigate how to stop irreversible transitions from pines to grasslands.
Using seedlings from 21 source tree locations spanning a broad elevation gradient across the region, they’ve been carrying out rigorous boot camp-style growing trials to find the most drought tolerant stock.
The seedlings are tested to the limits of their endurance, and beyond. So far, over 90% have died at the lower elevation test sites.
Some seedlings, though, are hanging on. Enough so that foresters hope using seeds with the toughest, most drought-tolerant genetics for future replanting efforts can give ponderosa forests of the Colorado Plateau the boost they need to potentially recover.