Southwest Biological Science Center
Recovery from disturbance represents a substantial challenge to agencies that manage large tracts of land in the Southwest. Despite the demand for restoration and rehabilitation, little information is available to help managers effectively reestablish native perennial vegetation and stabilize soils, especially given changing climate and disturbance regimes.
Forestry and agriculture have finely tuned their planting practices through the use of distributed networks of field trial, or “provenance” experiments. Ecological restoration outcomes could similarly be improved by adopting a field trial approach in which plots of different species and seed sources are established in monocultures and mixes, in combination with methods to improve their establishment, using a replicated, standardized approach within and across water-limited ecoregions.
Just below Glen Canyon Dam on the Colorado River is a very popular Blue Ribbon trout fishery known for its rainbow trout. However, approximately 78 miles downstream, near were the Little Colorado River flows into the Colorado River, is a population of endangered humpback chub. The introduced rainbow trout can negatively affect native humpback chub by competing with them for food (immature black flies and midges) and by preying on humpback chub. Therefore, it is important to understand rainbow trout movement and the abundance of these trout in the stretch of river directly below Glen Canyon Dam and the Little Colorado River. That information can help with maintaining the trout fishery while protecting humpback chub.
The objective of this interdisciplinary research effort is to 1) characterize agents of change important to land management decision makers on the Colorado Plateau; 2) identify and analyze relationships between agents of change and key landscape attributes and processes; 3) collectively assess the influence of agents of change and attributes and processes on the services provided by the ecosystem; and 4) provide managers with potential future visions of the Colorado Plateau using scenarios that will allow them to prescribe current management actions to achieve preferred resource conditions.
Deserts of the southwestern US are replete with oil and gas deposits as well as sites for solar, wind, and geothermal energy production. In the past, many of these resources have been too expensive to develop, but increased demand and new technologies have led to an increase in exploration and development. However, desert ecosystems generally have low resilience to disturbance. More frequent, intense droughts forecast for the southwestern US will likely further hamper recovery of disturbed lands. Consequently, there is a need for new science to anticipate and mitigate the effects of energy exploration and development. The Colorado Plateau Region contains approximately 100,000 abandoned and current wells spanning 60 years of activity. These structures are spread over a variety of substrates, climate zones, elevations, and vegetation communities, with varying periods of use and time since abandonment. The overarching goal of this project is to understand how past and current energy development are impacting the social-ecological systems of the Colorado Plateau, and to identify strategies to mitigate deleterious consequences of these activates now and into the future.
The overall goal of this project is to advance inter- and trans-disciplinary research coordination, focusing on the transformation of social-ecological systems by hydroelectric dam construction in the Amazon and the United States. The experience gained by Southwest Biological Science Center researchers working on the Glen Canyon Dam Adaptive Management Program in the Colorado River in Grand Canyon will be instructive in this collaboration.
Renewable energy development is expanding in southwestern deserts, including in Arizona. Energy developers look to resource management agencies to provide siting guidance on public lands where there might be conflicts with wildlife. Often, agency guidance considers species of conservation concern and economic importance, but information on comprehensive vertebrate biodiversity has been hard to incorporate. In this project, USGS researchers illustrate how biodiversity richness metrics for most vertebrate wildlife that can use an area and for sensitive guilds of wildlife such as bats, raptors, and migratory land birds can be incorporated into renewable energy siting decisions.
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 pests. However, there is great need to predict, prior to their introduction, which insects have the potential to result in high-impact invasions so risk assessment and management are informed.
A group of USGS, Forest Service, and university scientists are working together to study how ecology and evolution might be used to understand when introduced insects become high-impact. We are examining the contribution of five types of drivers toward these impacts: (1) the insects’ and host plants’ evolutionary history, (2) the hosts’ defenses or lack thereof (defense-free space), (3) presence of natural enemies or lack thereof (enemy release), (4) invader traits, and (5) geographic and temporal considerations.
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 understand how dam operations and the local environment may be affecting differences in drift concentrations, and thus higher levels of the food chain as well.
Aquatic insects are commonly used to gauge the health of stream and river ecosystems, yet collecting enough samples to adequately characterize a river segment as long as the Colorado River through Grand Canyon (> 250 miles) would be essentially impossible using traditional sampling methods. Since 2012, our group has been collaborating with river guides, private boaters, and educational groups to deploy light traps to collect adult aquatic insects in this river segment. These citizen scientists have generated an impressive quantity of samples and data, which are yielding fundamentally new insights into the Colorado River ecosystem.
Algae, phytoplankton, and rooted macrophytes represent the base of many aquatic food webs and are known as primary producers. Through photosynthesis, these organisms convert sunlight energy into chemical energy (i.e., carbon) that in turn fuels the growth of animals such as macroinvertebrates and fish. This project uses high frequency measurements of dissolved oxygen, which is a by-product of photosynthesis, to estimate rates of primary production at six locations in the Colorado River downstream of Glen Canyon Dam. Quantifying time series of primary production is used to identify the environmental factors that control primary production. Additionally, trends in primary production may be a leading indicator of changes in fish populations and the ecosystem as a whole.
Sediment controls the physical habitat of river ecosystems. Changes in the amount and areal distribution of different sediment types cause changes in river-channel form and river habitat. The amount and type of sediment suspended in the water column determines water clarity. Understanding sediment transport and the conditions under which sediment is deposited or eroded from the various environments in a river is therefore critical to understanding and managing sediment and sediment-related habitat in rivers. This project conducts and provides the science required to better understand the physics of sediment transport and channel change in rivers. All data collected by this project and user-interactive web tools to analyze these data are provided at either: https://www.gcmrc.gov/discharge_qw_sediment/ or https://cida.usgs.gov/gcmrc/discharge_qw_sediment/.
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 attributes may influence the trajectory of community change following Tamarix defoliation and mortality. This project aims to assess the physical and chemical drivers of plant colonization after beetle-induced Tamarix decline using long-term observational studies, field and greenhouse manipulation experiments, and a focus on providing resource managers with more information regarding management decisions that could help improve southwestern riparian zone community composition and function.