On June 22, 2005, multiple lightning strikes ignited a group of wildfires known as the Southern Nevada Fire Complex that burned approximately 403,000 acres of habitat characterized as potentially suitable for the desert tortoise, and more than 32,000 acres of designated Critical Habitat in (Prentice 2006). Mortalities of desert tortoises were observed after the fires, but the indirect effects due to habitat loss, shifts in the dominant vegetation from native shrubland to invasive grasses, emigration of tortoises away from burned habitat, and lower growth and reproductive output may have a more profound and lasting effect on desert tortoise populations influenced by these fires (Esque et al. 2003; Brooks and Esque 2003).

Project Details

In an effort to accelerate the re-establishment of plants important as food and necessary as thermal cover for desert tortoises, and reduce establishment of non-native grasses, the Bureau of Land Management (BLM) distributed native seeds in burned areas that are designated as desert tortoise Critical Habitat.

 

While the efficacy of post-fire seeding has met with recent criticism, many agree that quantitative monitoring is necessary to provide resource managers with the information needed for informed decisions on post-fire landscapes (Keeley et al. 2006). No published information exists on the efficacy of seeding in Mojave Desert upland habitats; however, a recent 4-yr study of re-seeded burned areas in northwestern Arizona suggest that seeding reduced the non-native annual grass red brome in a blackbrush community compared with unseeded burned areas (Scoles et al., unpublished data). No published data exist on how re-vegetation efforts such as re-seeding burned areas in the Mojave Desert impact sensitive wildlife such as the desert tortoise. Information about the efficacy of re-seeding efforts will guide future management of desert tortoise habitat because fire return intervals are becoming shorter within upland Mojave Desert habitats (Brooks and Minnich, In press) and will continue to challenge land management decisions.

 

The goal of this study is to monitor the success of hand-seeding native Mojave Desert annual and perennial species in burned desert tortoise habitat in and effort to 1) reduce the establishment of invasive non-native annual grasses, 2) accelerate the re-establishment of native plants reflective of the diversity, composition and eventual structure of unburned habitat and 3)encourage the movements and activity of tortoises back into burned habitat by providing the plants important as food and necessary as thermal cover for desert tortoises. Monitoring will determine whether the traditional approach of broadcast seeding across burned Mojave Desert landscapes will aid in containing, reducing and eventually suppressing populations of invasive annual grasses and restore habitat for use by this enigmatic desert reptile.

 

Current Activity:  Due to lack of precipitation stimulating production of invasive annual grasses, the herbicide application will occur in fall FY09. In fall, we will apply herbicides in combination with seeding to determine whether invasive annuals can be controlled to enhance seeding success. We will also plant greenhouse-grown blackbrush seedlings in combination with herbicides and soil moisture amendments (i.e., DriWater, starch-based polymer, mulch and hand watering). Monitoring will occur through summer 2009.

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