Adaptive Management

Although most introduced insects are relatively benign, some become high-impact pests causing widespread ecological and economic damage. Introduced insects that are specialists and feed on a single genus of plants can be high-impact as they can potentially eliminate an entire native plant genus over large areas. Luckily, most introduced insects with this feeding behavior do not become high-impact...

Aquatic invertebrates are critical food for fish and other species that inhabit large rivers. In the Colorado River Basin, invertebrates that get transported down the river (“in the drift”) are particularly important to rainbow trout and other species of interest to recreational users. This research seeks to compare rivers downstream of large dams throughout the Colorado River Basin in order to...

Introductions of bio-control beetles (genus Diorhabda) are causing defoliation and dieback of exotic Tamarix spp. in riparian zones across the western U.S., yet the factors that determine the plant communities that follow Tamarix decline are poorly understood. In particular, Tamarix-dominated soils are often higher in nutrients, organic matter, and salts than nearby soils, and these soil...

Introduced rainbow trout and brown trout are considered a threat to the endangered humpback chub in the Colorado River in Grand Canyon. These introduced species eat native fish, but impacts are difficult to assess because predation vulnerability depends on the physical conditions under which predation takes place. We studied how predation vulnerability of juvenile humpback chub changes in response...

Riparian vegetation has increased dramatically along the Colorado River downstream of Glen Canyon Dam since the closure of the dam in 1963. The spatial patterns and temporal rates of vegetation increase occur due to changes in river hydrology, dam operations, and climate. The increase in vegetation, particularly onto otherwise bare sandbars, has impacted recreational, geomorphological, biological...

Dryland regions have been degraded by invasive species, wildfire, overgrazing, agricultural conversion, energy development, recreational activity, and urban growth. These disturbances and others are accelerated by one of the fastest growing human populations in the country and a pressing background of decreasing water availability due to drought and elevated temperatures that are projected to...

In the southwest US, monsoon precipitation increases sharply along a northwest to southeast gradient. Pleuraphis jamesii or galleta grass, is an important C4 grass species that spans across this large range in precipitation pattern. In this study we are assessing the ability of galleta grass to adapt to changes in the seasonality of rainfall (termed “plasticity”). In the fall of 2014, we...

Forests in the semiarid southwestern U.S. are expected to be highly vulnerable to increasing aridity anticipated with climate change. In particular, low elevation forests and the processes of tree regeneration and mortality are likely to be highly susceptible to climate change. This work seeks to characterize how, where and when forest ecosystems will change and identify management strategies to...

Drylands cover 40% of the global terrestrial surface and provide important ecosystem services. However, climate forecasts in most dryland regions, especially the southwest U.S., call for increasing aridity. Specifically, changing climate will alter soil water availability, which exerts dominant control over ecosystem structure and function in water-limited, dryland ecosystems. This research seeks...

Historic over-grazing of arid grasslands in the Intermountain West has led to widespread soil erosion, loss of plant diversity, and invasion by exotic species. Degraded grassland conditions can be very persistent, even after livestock use has ceased. For example, in national parks on the Colorado Plateau, livestock have been excluded for decades, but soil and native plants have not recovered on...

Although it is not listed on the Federal Endangered Species list, there is considerable concern over northern leopard frog declines in western North America. It is listed as a “special concern” species by some state wildlife agencies (e.g., Arizona Game and Fish Department 1996) and declines have been reported in Arizona, Colorado, New Mexico, and other areas across the west. Leopard frogs have...

Economic research at Grand Canyon Monitoring and Research Center is used to determine economic benefits of outdoor recreation in Glen Canyon National Recreation Area below Glen Canyon Dam and in Grand Canyon National Park, as affected by operation of Glen Canyon Dam. This research identifies recreationists’ preferences for attributes associated with their trips, spending that occurs regionally...