Managing Military Lands in the Southwest

The Ecology of Fire, Invasives, and Water in the Southwest

SERDP researchers are developing the science and tools needed to manage and recover ecosystems on military installations and ranges in the southwestern United States. This work will help the Department of Defense sustain military training and testing capabilities in the Southwest. The long-term use of these lands depends, in part, on the ability to maintain the continued ecological functioning of the land base. Human population pressure and associated land-use activity, altered hydrologic regimes, and non-native species introductions are relatively new perturbations in this region. Global climate change also will result in region-specific changes in temperature, precipitation regimes, and extreme weather events including drought that will exacerbate these impacts.

Altered Fire Regimes and Non-Native Invasive Plants

Altered Fire Regimes and Non-Native Invasive Plants

Interactions between plant invasion and increases in fire frequency and magnitude are a growing concern in the Southwest. Plant invasions have had their greatest effects on fire regimes at lower elevations, especially in desert scrub systems. Future shifts in climate could affect the relative abundances of these vegetation types and increase the dominance of non-native invasive plants. The individual and synergistic impacts of invasive plants, fire, and global climate change on native habitats will affect threatened, sensitive, or at-risk species in complex ways.

SERDP researchers are developing decision-support tools that DoD and other land managers can use to more effectively and efficiently manage non-native invasive plant species and wildfire in the Sonoran and Mojave Deserts now and under changing climate conditions. They are also examining the population strategies used by non-native plants to spread into areas between desert shrubs, increasing fuel loads and changing desert communities and landscapes.

Intermittent and Ephemeral Stream Systems

Intermittent and Ephemeral Stream Systems

More than 80 percent of all streams in the six southwestern states—Arizona, New Mexico, Utah, Nevada, Colorado, and California—are intermittent or ephemeral (only flow during rain events). These dryland streams and their associated riparian zones play a significant role in supporting the biological diversity of this region. Intermittent and ephemeral streams transport and retain water, nutrients, sediments, and organic matter episodically in their networks and associated floodplains, support the establishment and maintenance of riparian vegetation, and provide ecologic and hydrologic connectivity to uplands and to downstream perennial watercourses.

SERDP researchers are assessing intermittent and ephemeral streams at sites across the southwestern United States to develop a landscape-scale classification and measurement methodology that distinguishes channel types by a set of biotic and abiotic attributes, which are directly related to their hydrologic regime. They are also characterizing streams and developing a stream hydrogeomorphic classification system incorporating key physical process drivers that create and support riverine and riparian landforms, hydrologic regimes, and biota in the Sonoran Desert. The resulting tools will enable DoD land managers to map stream types and evaluate the impacts of perturbations on the hydrologic regimes of these systems and the species that depend on them.

How intermittent and ephemeral streams provide critical habitat and population connectivity for aquatic species (insects and amphibians) is the subject of SERDP research at Fort Huachuca in southeastern Arizona. Researchers are assessing whether these ecological functions will be maintained in a changing climate. Quantitative models that forecast the ecological and genetic consequences of altered hydrologic connectivity will help identify aquatic taxa whose persistence are particularly jeopardized and that may require active management efforts such as corridor connections, translocations, or water management.

To improve understanding of the linkages between abiotic processes and biotic communities and how they are influenced by hydroclimatology and anthropogenic land and water use, SERDP researchers also are studying three sites across the Sonoran Desert and southeastern Arizona that represent stream systems differing in duration, intensity, and frequency of seasonal precipitation events and water table depths. The results of this study will aid DoD land managers in prioritizing locations for stream recovery and protection.

Informing Land Management Decisions

Delivering the results of this research in user-friendly ways to resource managers is critical. On May 16, 2012, an Installation Resource Manager's Workshop was held in Tucson, Arizona, in conjunction with the annual In-Progress Review for the seven research teams highlighted above and listed below. Attendees included natural resource managers from Fort Irwin, Yuma Proving Ground, Fort Huachuca, Barry M. Goldwater (Luke) Air Force Range, and White Sands Missile Range and representatives from SERDP, its Resource Conservation and Climate Change technical committee, and the project teams. The workshop fostered dialog between the research teams and installation managers and facilitated synergistic collaboration across projects focused on different scales of analysis and geographic emphasis. Much of the workshop discussion centered on identifying tools that will enhance management decisions by installation managers and on troubleshooting technical difficulties with the delivery and future use of such tools. Tool refinement during the final phases of the research projects is planned to ensure that the results are beneficial and usable to the managers.

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