Cooperating Agencies:

• Maricopa County Parks & Recreation

Location:

About 40 km (25 miles) north of Phoenix in the Cave Creek Regional Park.

Date Initiated:

2005

Description:

In the summer of 2005, a human-caused wildfire burned about 4 acres in Cave Creek Regional Park, north of Phoenix. John Gunn, park manager at the time, prepared a restoration project for the burned area that included seeding a mix of more than 20 native plant species and adding straw mulch to assist plant establishment on the site.

Conventional wisdom has it that re-seeding disturbed areas in desert environments does not work due to harsh conditions, including high temperatures and sparse, unpredictable rainfall. Since hard evidence for or against this assertion is lacking, because most desert re-seeding projects have not been scientifically monitored, Gunn contacted ERI Associate Director, Diane Vosick, to inquire about starting a monitoring program to gauge the success of the seeding project.

In the fall of 2005, ERI Research Specialist, Scott Abella, and two ERI botanists travelled to Cave Creek and, along with Gunn and his colleagues, established 22 monitoring plots in the seeded area. They then recorded the species present on each 10-m2 plot and estimated their aerial cover. They also estimated mulch cover because Gunn and Abella were interested to see how long the mulch, with its beneficial effects on plant establishment, would persist on the ground. Vegetation on the Cave Creek plots was re-measured in the spring and fall of 2006, and again in the spring of 2007.

During the time of the experiment, rainfall was even lower than usual in the Cave Creek area, which would seem to doom attempts to revegetate the site. However, despite the low rainfall, there has been a general increase in cover on the burned site, compared to adjacent burned and unseeded private land. A number of the seeded species have become established at the site (Table 1), and several species have done rather well, including the shrubby forb, desert senna (Senna covesii), and the grass, purple threeawn (Aristida purpurea).

ERI botanists hope that by conducting more research like this, and by disseminating the results to land managers in a position to use the findings, we can learn how to effectively revegetate disturbed areas of the Sonoran Desert, and reverse some of the degradation that has occurred in this harsh, fragile environment.

Table 1. Establishment of seeded species and volunteers on a Sonoran Desert Burn, Cave Creek Regional Park, Arizona.

1 These species were seeded but showed little establishment: Grasses: cane bluestem (Bothriochloa barbinodis), side-oats grama (Bouteloua curtipendula), Rothrock’s grama (Bouteloua rothrockii), plains lovegrass (Eragrostis intermedia), bush muhly (Muhlenbergia porteri), vine mesquite (Panicum obtusum), plains bristlegrass (Setaria vulpiseta), spike dropseed (Sporobolus cryptandrus); Shrubs: fairyduster (Calliandra eriophylla), creosote bush (Larrea tridentate); Forbs: trailing windmills (Allionia incarnate), exserted Indian paintbrush (Castilleja exserta).

2 Based on twenty-two 10-m2 plots.

Project Status:

The originally agreed-upon measurements have been conducted, and the data analyzed for publication. The experiment is ongoing, however, and ERI botanists will likely return from time to time to monitor the results.

For More Information:

• Contact Mark Daniels, at

Publications:

In 2007, Abella, Gunn, and ERI staff co-authored and submitted a manuscript with findings from the project for review to Native Plants Journal.