Restoration Initiatives

Predicting cheatgrass invasion at the landscape scale

Identifying the environmental conditions that influence the occurrence of cheatgrass is essential for targeting restoration efforts and deterring further spread. Using information collected in our baseline assessment, we are working with researchers from Northern Arizona University to develop landscape-scale models of cheatgrass occurrence across the entire ranch landscape.

Introduction

The ecological impacts of non-native invasive species is recognized as a global problem and numerous researchers have concluded that invasive plant species represent one of the greatest threats to biodiversity. On the Kane and Two Mile Ranches, and throughout the southwestern United States, historical livestock grazing practices, wildland fire, and regional changes in climate have facilitated the establishment of invasive non-native species, such as cheatgrass (Bromus tectorum). In turn, cheatgrass invasion threatens to diminish the biological integrity of grassland, shrubland, and forested ecosystems on the landscape. Cheatgrass is particularly difficult to remove once it has become established and can dominate some areas as it crowds out native plant species and causes changes to natural fire cycles. Identifying the environmental conditions that influence the occurrence of cheatgrass is essential for targeting restoration efforts and mitigating further spread.

Approach

We have worked with researchers from Northern Arizona University to develop a landscape-scale model that predicts the occurrence of cheatgrass across the entire 345,000-hectare Kane and Two Mile Ranches. This model was produced using data collected at 606 ground plots during the 2005 Baseline Assessment , and coupled with information on climate, soil texture, terrain features, and the presence of roads, grazing, and fire. Results from this modeling effort highlight the importance of fire and climate as primary determinants of cheatgrass occurrence and provide the foundation for developing additional hypotheses related to abundance and spread at local and landscape scales (e.g., within the Warm Fire burn perimeter and on the West Side of the Kaibab Plateau).

Future Work

Results and maps from our cheatgrass modeling effort will be submitted to peer-reviewed journals and disseminated to land managers and other interested stakeholders in the region. Our cheatgrass occurrence and spread maps will be key to guiding ongoing habitat enhancement work with the Arizona Game and Fish Department on the west side of the Kaibab Plateau and implementing measures with the U.S. Forest Service to prevent invasion into the Warm Fire burn area on the east side of the Plateau. Further, we will combine our cheatgrass model with models describing forest conditions so as to better understand interactions between fire, invasive species, and wildlife habitat use. We intend to use these datasets in a collaborative landscape assessment and pioneer integrated, science-based landscape-scale forest restoration and fire management strategies across the Kane and Two Mile Ranches.