State of Arnett Creek
January 2017

Tamarisk and oleander in retreat: Native plants, birds, and fish take the lead

Arnett Creek is a lesser-known riparian area near Superior, Arizona. It’s notable for stretches of perennial water, which is rare and important in the Sonoran desert, and critical for birds, amphibians and fish that depend on water for their livelihood. AWC worked in partnership with the Friends of the Tonto National Forest to develop a plan to improve habitat in Arnett Creek for threatened and sensitive species, particularly the Yellow-billed cuckoo, Longfin dace and Lowland leopard frog.

A key threat identified to Arnett's healthy riparian system was extensive spread of non-native Tamarisk and Oleander. Removing the thick growth of these trees and shrubs proved challenging, complicated by substances produced by Oleander that are toxic if ingested. It proved no easy task to develop methods to treat and remove the invasive species, while protecting desirable plants and also engaging large numbers of volunteers and partner groups. Throughout the project, it was important to approach all tasks in the manner acceptable to the land managers, the Tonto National Forest.

Read more below about the challenges in implementing this daunting project, and learn more here about the exciting earlier research that aimed to link planned on-the-ground action with meaningful ecological outcomes.

Challenge accepted: Partners, students, and horses, restore the Creek

The Arnett Creek Project provided the platform for successful collaboration between multiple partners, all committed to the reduction of invasive Tamarisk and Oleander along this stream well-known for its recreational potential.  After months of planning in conjunction with the Tonto National Forest, Arizona Wilderness Coalition staff and volunteers converged with members of the Arizona Trail Association, Friends of the Tonto National Forest, Arizona Conservation Corps, and students and faculty from Prescott College for a three-week-long intensive eradication effort in late 2016.

The first group arrived in mid-November, as AWC staff and volunteers worked with a Maps and Land Navigation class from Prescott College. The initial assignment served a dual purpose, mapping the exact location and approximate size of Tamarisk and Oleander.  In the next phase, AWC welcomed a freshman class studying Water in the West. Volunteers joined with this class to cut and bag Oleander for removal. The stumps were sprayed with an herbicide and the bagged oleander was hauled out by hand. Crews were justifiably exhausted, as 60 heavy-duty trash bags full of debris were packed out and loaded into a trailer, then hauled to a transfer station in Apache Junction. 1250 pounds of oleander was recorded, that’s over a half a ton!  

Following the Thanksgiving holiday, the Back Country Horsemen arrived with their horses to haul in chainsaws, water and herbicides for the final phase of the project. As an area outside any wilderness areas, chainsaw use was permissible in Arnett Creek. Meanwhile, the data collected previously was compiled and used by another Prescott College class to develop detailed maps for project documentation and future monitoring. A team from the Arizona Conservation Corps then arrived to spray, cut and stack Tamarisk in burn piles, assisted by AWC staff and volunteers.

All told, it’s estimated that roughly 70% of the Oleander and Tamarisk was cut and treated, a major feat given the thick growth of these invasive species. A project of this magnitude could not have been successfully completed without the perseverance of many partners and volunteers. AWC is especially grateful for the coordinating role of our Wilderness Stewardship Coordinator Brian Stultz, and the able assistance of our Stewardship Project Assistant, Stephanie Landers Hanse.

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State of Arnett Creek
June 2016

Survey Photos

“There’s a frog right there!” exclaimed Daniel Lehman to fellow surveyors, pointing through the darkness with his brilliant flashlight at the edges of a swirling cloud of muck in a small pool along Arnett Creek. Lehman, the reptile expert for the Tucson Audubon Society’s field crew, had just seen the first of nine lowland leopard frogs that the crew encountered that night. “The numbers [of leopard frogs] was surprising,” he said afterwards. “It seemed so dry while doing the veg surveys during the day.”

In April, Audubon prepared a baseline conditions report for Arnett Creek, located east of Phoenix near the Boyce Thompson Arboretum. The report aims to inform a restoration project planned by AWC for this fall. TAS documented the presence or absence of species the work is intended to benefit - lowland leopard frog, yellow-billed cuckoo, and longfin dace – and surveyed vegetative conditions along the creek that support those species. The baseline will enable documentation of any improvements that may result from the habitat restoration project. Restoration work will include removing invasive species like deciduous saltcedar, oleander, palm trees, and others.

We found that overall, conditions in the project area for the target species improve as one moves upstream; it gets wetter, the pools are larger and deeper, the cottonwoods, willows, and ash trees are denser and taller. All frogs documented were in the upstream quarter of the project area, and that is the only area that looks like possible current cuckoo habitat – an assessment that will be verified when the federally approved survey window for cuckoos begins in mid-June. As well, the only areas of standing water during the survey period were in the upstream reaches.

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“One ‘fravel’ in the density column” says Jonathan Horst, Conservation Director for Tucson Audubon. Vegetation surveys included both percent cover and density of perennial plants on 12 transects through the project area. Photo courtesy of Dan Lehman.	Vegetation surveys require following where the tape lies in the straightest line possible…even if it means directly through the thickest of cover, or through a blank area. Photo courtesy of Jonathan Horst.	Nibbling an evening snack and serenaded by prowling elf owls, Rodd Lancaster and Andy Bennett await full dark so the leopard frog surveys could begin. Photo courtesy of Jonathan Horst.
Lehman gets a close-up of a gopher snake the crew encountered on the first day of surveys. Photo courtesy of Jonathan Horst.	A lowland leopard frog on the edge of a pool in Arnett Creek. Only a couple frogs sang all night; most lingered on the edges of pools silently, or hid in the muck and leaves. Photo courtesy of Jonathan Horst.	“Surveying for leopard frogs in Arnett Creek was a bit of a surreal experience. We could hear civilization was close by, but being enclosed in utter darkness in a completely wild-feeling area with only a small halo of light by which to search…yeah, that was a good day and night of work” said Horst. Photo courtesy of Jonathan Horst.

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