Colorado River
Arizona's Bill Williams River Part of the Colorado River system. © Tana Kappel/The Nature Conservancy


Nature Briefs

This page was updated on January 17, 2023.


In Arizona, perennial streams are a rarity, but Aravaipa Creek—located northeast of Tucson—defies expectation. While most streams are dwindling due to climate change and the overuse of groundwater, the 20-mile Aravaipa flows year-round, sustaining a riparian oasis of cottonwoods and willows and the state’s best remaining assemblage of native desert fishes. In the past, the stream’s outlook wasn’t so promising. When Mark Haberstich started managing TNC’s Aravaipa Canyon Preserve more than 25 years ago, an analysis of its flow showed a declining trend that was expected to worsen. Yet over the last 10 years, the trend has been on the upswing. Mark’s work to plant native grass on the floodplain—along with streambank management and controlled burns—has helped the ground act like a sponge that stores water and releases it slowly downstream. In 2021, TNC facilitated the public acquisition and protection of a property that supplies up to half of the creek’s water. A recent fish survey found that the endangered spikedace has expanded its range and is now present throughout the stream.

Mark Haberstich, Aravaipa Preserve Manager in Oak Grove Canyon.
Hiking Aravaipa Canyon Mark Haberstich, Aravaipa Preserve Manager in Oak Grove Canyon. © Aaron Mrotek/TNC


Healthy trees are essential to healthy communities. They purify air, offer cooling shade and help manage stormwater—all crucial to combating climate change. While mature trees provide the greatest benefits for people and nature, they also require monitoring and maintenance to improve their resilience and longevity. That’s why in 2020 TNC and partners launched Treesilience, a national initiative that eliminates the often-expensive barriers to healthy urban tree canopies by removing and replacing dead or dying trees, pruning and site-planting preparation. Treesilience works with local partners and workforce development programs to offer these services for free on private properties in frontline communities. Currently, the initiative has roots in Chicago, Orlando and St. Louis, with plans to expand across the U.S. to cities where people stand to gain the most from resilient forests. TNC’s Urban Forestry Strategist Rachel Holmes says, “The hope is that Treesilience continues to be a growing movement that inspires communities to care for the trees that already give us so much.”

Partners held a kickoff event on 12.2.21 with a tree removal and planting in Pine Lawn, MO.
Treesilience Alderwoman Bettie Lee, Mayor Terry Epps and homeowner Dorothy Collins plant a tree at the Treesilience kickoff ceremony in St. Louis. © Kristen Stoyer/TNC