Status of Terrestrial Vegetation and Soils at Tonto National Monument (2024)
Hubbard JA , Studd SE , McIntyre CL , Pingatore A . 2026. Status of Terrestrial Vegetation and Soils at Tonto National Monument (2024). Science Report. NPS/SR—2026/500. National Park Service. Fort Collins, Colorado. https://doi.org/10.36967/2305227
This report summarizes results of the Sonoran Desert Network 2024 terrestrial vegetation and soils monitoring in upland areas of Tonto National Monument. Data from 17 plots distributed across the three elevation zones of the park—valley floor, bajada, and rocky foothills—were analyzed in the context of key management issues including erosion hazard, fire hazard, saguaro cactus recruitment and extent, plant community resilience, and exotic plant invasion. Fire hazard is extremely high due to the proliferation of red brome parkwide. This aggressively invasive annual grass dominates the ground cover in wet years and is ever-present, even in dry years, forming a fuel continuum between otherwise widely spaced shrubs and trees. Red brome is present in 100% of the sampling sites and represents 29–47% of the total plant cover. This is a considerable management concern with long-ranging impacts and environmental risks such as loss of species richness, type conversion to fire-adapted grasslands, and damage to cultural resources through uncontrolled wildfire. Saguaros are not present in all sites that have suitable habitat, which might suggest unsuccessful recruitment. Additionally, the cover of plant species known to provide nurse environments to seedling and juvenile saguaros is below our management assessment point and could be contributing to low distribution of saguaros. The data indicate that erosion hazards are low, with stable soil aggregates, low exposed bare ground, and well-established biocrust communities, providing good protection against wind and water erosion.
- Type
- Published Report
- Authors
- Hubbard, J.; Studd, Sarah; McIntyre, Cheryl; Pingatore, Adam
- Date of Issue
- 2026-08
- Publisher
- National Park Service
- DOI
- 10.36967/2305227
- Units
- NRSS , SODN , TONT
- Keywords
- ecology, long term monitoring, management assessment points, plants, soil, terrestrial ecosystems, terrestrial vegetation and soils
- Subjects
- Ecological Framework: Biological Integrity | Invasive Species | Invasive/Exotic plants , Ecological Framework: Biological Integrity | Focal Species or Communities | Desert Communities , Ecological Framework: Biological Integrity | Focal Species or Communities | Grassland/Herbaceous Communities , Ecological Framework: Biological Integrity | Focal Species or Communities | Shrubland Communities , Ecological Framework: Biological Integrity | Focal Species or Communities | Vegetation Complex