Intensive Revegetation in Arizona's Hot Desert: The Advantages of Container Stock

Abstract

We found that the most effective and economical method for establishing native shrubs on extensive areas of retired cropland in southern Arizona makes use of drip irrigation and 3.8-l (1-gal) transplants (outplants). In March 2001, we established a small (8 ha [20 ac]) field trial to test the effectiveness of different combinations of transplanting, seeding, drip irrigation, and furrow irrigation. Treatments utilizing transplants and drip irrigation had higher survival and lower densities of weed species than other treatments tested. Based on these results, we planted again in November 2001 using drip-irrigated transplants to examine the effectiveness of this method over a larger scale (85 ha [210 ac]). As a further refinement of this method, we tested various sizes of container stock and determined that transplants of 3.8-l (1gal) size had superior growth and survival when compared to smaller-sized transplants. The total cost of this method is approximately US$ 4430/ha ($1790/ac), but it is more likely to succeed as compared with direct seedings, which is a commonly used approach to revegetation in southwestern ecosystems. Although a drastic effort, our technique holds promise for revegetating environments in the hottest and driest parts of the Sonoran Desert in southern Arizona.

Revegetating Disturbance in National Parks: Reestablishing Native Plants in Saguaro National Park, Sonoran Desert

“…ex Griffiths (blue grama) was low after 2.5 years, at only 18% and 28%, respectively. These and other studies indicate that revegetation effectiveness can sharply vary depending on method (seeding versus planting), species, and treatment (e.g., irrigation or cages to provide herbivory protection) used for revegetation (Roundy et al 2001;Bean et al 2004;Abella and Newton 2009). No well-established protocols exist for revegetating planned or unplanned disturbances in deserts, and financial cost projections for accomplishing revegetation are rare.…”

“…For example, included 28 species in their seed mix, with 14 species established by one year after seeding and only five species occupying ≥50% of 10-m 2 plots three years after seeding. Other seeding studies in the Sonoran Desert have reported no (Bainbridge and Virginia 1990;Woods et al 2012) or minimal plant establishment (Bean et al 2004), or have noted limited establishment based on retrospectively measuring plant community composition of seeded sites (Judd and Judd 1976;Jackson et al 1991;Banerjee et al 2006). The next most species-rich outplanting study in the Sonoran Desert, Bean et al (2004), reported that at least six species of shrubs and grasses exhibited ≥69% one-year survival on derelict farmland.…”

“…Reliable revegetation protocols are also important for supporting decisions about attempting revegetation of unplanned disturbances. Managers can make decisions based on considerations such as how effective active revegetation is compared to natural recovery and the resources and financial expenditures needed to achieve the revegetation (Bean et al 2004). …”

“…Gray) S. Watson (blue paloverde) outplants was 80% with active irrigation, whereas seeding did not successfully establish this species. On derelict farmland, Bean et al (2004) reported that one-year survival exceeded 60% for outplants (all plants were irrigated) that had been greenhouse-grown in 3.8-L containers of some species such as Ambrosia dumosa (Gray) Payne (burrobush), Larrea tridentata (Sessé & Moc. ex DC.)…”

Planting Trials in Northern Arizona Ponderosa Pine Forests

“…The volcanic cinder soils on which this trial was conducted are among the driest in the Flagstaff area, with a 0 to 15 cm gravimetric soil moisture content of less than 2% in early summer (Abella and Covington 2006). We did not provide any supplemental water to outplants, and irrigation (where practical) or slow-release irrigation (such as DriWater) may be especially important for outplants on these dry soils (Newton 2001, Bean et al 2004). Another consideration is that plants were five months old and 10 cm tall on average at the time of planting.…”