Hydrology and post fire burn response was the focus of this trip. We were joined by Kelly Mott Lacroix, Tonto NF Watershed Program Manager and Forest Hydrologist and Brooke Wheelock, Tonto NF Volunteer Outreach Coordinator. TRAL really appreciates the effort made on behalf of the Forest Service to make time for our volunteers. Thank you Kelly and Brooke! The area we chose for this trip was Four Peaks Road, where in June, 2020 the Bush fire eventually burned nearly 200,000 acres.
The Inciweb map of the Bush Fire.
The Bush Fire started near Bush Highway and took a quite destructive path burning and killing thousands of saguaros and other cacti as it tore through the Desert Sonoran ecosystem at the lower elevations. This fire spread rapidly due to the abundance of invasive species grasses (primarily Red Brome grass) in the area and was carried up through Chaparral and into Manzanita thickets and over the top of Four Peaks, eventually consuming the small Ponderosa Pine ecosystem found there. This was a working trip for Kelly, she needed to see how the area had responded to the fire both visually and quantitatively by sampling the soil for hydrophobic response and the measuring water samples for dissolved oxygen content and temperature.
Kelly Mott Lacroix demonstrating how dissolved oxygen levels are measured at Picadilla Creek.
In each ecosystem the burn response 10 months after the burn was quite different. Fires are not all consuming. In any fire, there are always pockets that were not burned. Lower elevation desert plants such as cacti, are not well fire adapted. The burn response tends to be very slow, grasses and invasive grasses, which are fire adapted tend to come back first. At higher elevations, the plant life becomes more woody and the plants are more fire adapted. Fire happens with some regularity in those ecosystems and the plants that have managed to survive there have adapted to it and can come back from even the most catastrophic fires. Almost everywhere we looked we saw new growth being established from the charred remains of previous plant life. Kelly mentioned that the fire recovery at higher elevation typically takes five years. At lower elevations, the saguaro forests that we loved may never come back.
We stopped at several Riparian areas on our way to the top which showed a great response to the fire. New Sycamore, Fremont Cottonwoods, Arizona Walnut, Willow and Oak could be seen. We even spotted a small frog in the waters of Picadilla Creek. Can you spot him in this picture?
Kelly also talked to us about how TRAL could help her in identifying issues in areas where motorized trails cross running water.