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Research Work Unit 4351

Research Work Unit Title

Ecology, recovery, and sustainability of southwestern grassland and associated riparian ecosystems and wildlife.

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Area of Research Applicability

New Mexico, Arizona, Colorado, Texas, Oklahoma, Mexico

MISSION. Develop, synthesize, and apply new methods and knowledge on processes, interactions, and human uses of desert, prairie, and riparian ecosystems to restore damaged lands, recover sensitive species, and sustain intact, productive, and diverse plant and wildlife communities and associated abiotic systems in the Southwest.
PROBLEM 1. Nonsustainable management of grazing, fire, woody and alien species, and wildlife has led to widespread disturbance and degradation of southwestern and southern-plains grasslands and associated ecosystems. The development of new methods and knowledge are needed to restore damaged systems and recover sensitive and endangered species.

Users and Cooperators. Land managers, private industry (mining, ranching), environmental groups, and research colleagues will use information derived from studies that address Problem 1. Information will be used to plan prescribed fires and other treatments in ways that will benefit ecosystems while avoiding destruction of essential wildlife habitat features such as bat roosts. Managers, mining companies, and ranchers will use information to restore properties altered by overgrazing and fire exclusion. Managers and environmental groups will share knowledge with their constituencies about the status of bird and bat species and measures that can be used to prevent population declines. Information will be used to prevent, prepare, and respond to endangered species litigation. Specific users include New Mexico Environment Department, City of Albuquerque, New Mexico State Parks, Bureau of Land Management, Bandelier National Monument, Indian Pueblos, Navaho Nation, Black Kettle and Kiowa/Rita Blanca National Grasslands, Gila, Tonto, Cibola, and Santa Fe National Grasslands, Forest Guardians, BatConservation International, Partners in Flight, New Mexico Game and Fish Department, National Audubon Society, and Albuquerque Wildlife Federation. Cooperating research institutions include University of New Mexico, New Mexico State University, University of Arizona, Sevilleta Long-Term Ecological Research, Sutton Avian Research Center, UNM Natural Heritage Program, and USGS Biological Resources Division.

In order to specifically define the research approach needed to solve Problem 1, its components have been separated into four elements.


Element 1. Evaluate the influence of fire as an agent of natural disturbance that regulates ecological processes in southwestern and national grasslands and assess its value as a means for restoring grassland ecosystems, including the maintenance of native diversity and control of noxious weeds and undesirable woody plants.

Specific approaches include implementation of a fully replicated mid-scale (2 hectare) plot study on the Kiowa National Grassland with fire intervals of three, six, and nine years as well as dormant season and growing season burns to test seasonality effects. As a component of this study, small mammals will be live-trapped and marked prior to and following fire treatments on inset grids, and arthropods will be sampled pre- and post-treatment using pitfalls. Other studies currently underway are evaluating the potential for immediate reintroduction of fire into grassland ecosystems. Sites were chosen, and burned, that represented two different degrees of degradation. All sites are being monitored for changes in vegetation composition, abundance, and productivity. Soils are being monitored for changes in nutrient availability and chemical composition. Erosion bridges are used to monitor changes in soil microtopograpy (indicates soil erosion or aggregation). Small scale hydrological responses are being monitored using soil moisture probes and 3 X 10 meter runoff plots, while other studies plan to use 150+ hectare watersheds to describe more broad-scale responses to prescribed fire.

Element 2. Determine the efficacy of mechanical and chemical woody plant removal as ecological restoration techniques for grassland ecosystems that require alteration of composition and structure before they can be burned.

Reintroduction of fire into grassland ecosystems is proposed as a means of increasing the stability, diversity and productivity of southwestern plant communities (see Element 1). However, if degradation has progressed to the point that the herbaceous understory has been removed or severely damaged, it may not be possible to effectively reintroduce fire without first stabilizing the soils and increasing herbaceous productivity to the point where sufficient fine fuels are provided. Woody plant thinning and alternative grazing management need to be evaluated to determine whether these techniques can contribute to reducing competition between woody plants and grasses, retaining greater amounts of precipitation on site, stabilizing soils and increasing herbaceous production to the point where fire can be successfully reintroduced and subsequently used for maintenance of grassland ecosystem health.

Study sites that are judged not to have enough herbaceous fuels for immediate reintroduction of fire will undergo prefire treatments such as woody plant thinning and herbicide treatment to increase fuel loads. Fire will be reintroduced into these sites when fuel loads are appropriate. Most sites are removed from grazing during the restoration phase but grazing can be reintroduced as a management treatment once the sites have been restored. All sites planned for treatment will be monitored for changes in vegetation composition, abundance, and productivity. Soils will be monitored for changes in nutrient availability and chemical composition. Erosion bridges are used to monitor changes in soil microtopograpy (indicates soil erosion or aggregation). Small scale hydrological responses will be monitored using soil moisture probes, while other studies plan to use 150+ hectare watersheds to describe more broad-scale responses to treatments.


Element 3. Assess the habitat ecology and roost site selection of sensitive bat species and identify natural and anthropogenic factors that disturb bat populations.

Bat species composition and general periods of activity will be identified at ten pinyon-juniper sites on the Cibola National Forest. Mist nets will be use to identify bats by species, sex, age, reproductive status, weight, and time captured. The most frequently captured Species of Concern, Myotis volans, M. evotis, and M. thysanodes, will be fitted with radio transmitters and tracked to obtain information on type and location of roosts, number of roosts used, and roost fidelity. Reproductive females will be the primary target of radiotracking because they will lead to maternity colony locations. Once a roost is located, roost type and microsite characteristics will be evaluated, and location will be recorded using GPS. Roosts and their local habitats will be compared to random or unused sites to determine if certain roost site characteristics or locations are actively selected for. In addition to roost characteristics such as canopy cover, roost aspect, and tree size, factors such as elevation, roost distance to water, and distance to roads will be measured.

Element 4. Assess whether grazing schedules can be altered to improve habitats for endangered, threatened and sensitive bird species in grassland ecosystems.


Research is needed to determine why populations of grassland bird species are declining, and whether improvements in grazing management practices will mitigate this problem. A study evaluating population dynamics, species richness, and habitat use of wintering birds was initiated in 1999 within grassland ecosystems of the Sevilleta National Wildlife Refuge. The study is designed to estimate bird populations over a five-year period in grazed and ungrazed grasslands. In 2001, selected bird study sites are scheduled for prescribed fires to determine if fire treatment improves grassland productivity and bird habitat use in grazed and ungrazed areas. Migratory Mountain Plovers, a species federally-listed as Threatened in 2000 were observed using study sites in March 2000. This study is conducted in collaboration with the Sevilleta Long-Term Ecological Research Site managed by University of New Mexico.


PROBLEM 2. Disturbances such as grazing, roads, stream channel realignments, and exotic plant invasion have altered hydrological, biological, and ecological dynamics of riparian habitats, endangering terrestrial native plant and nongame bird species. New methods and knowledge are required to recover terrestrial riparian systems and associated sensitive species.

Multi-unit research priorities for riparian zones of the middle Rio Grande valley were defined under Problem 3 of the Rio Grande Ecosystem Research Program (RWU 4652). Here, we narrow the focus to discuss those priorities for riparian research pertinent to RWU 4351.

Research is needed to assess the influences of road construction and exotic plant invasion on habitat availability, suitability, and succession and wildlife populations in riparian and wet meadow ecosystems. Additional research on the aquatic, botanical, hydrological, and geomorphological dimensions of riparian ecosystems in the Southwest is addressed by RWU 4302 (Flagstaff, AZ).

Cooperators and Users. In the Southwest, numerous federal, state, and private agencies including the National Forest System, the Bureaus of Land Management and Reclamation, the Army Corps of Engineers, Federal Highway Administration, the City of Albuquerque's Open Space Commission, the U.S. Fish and Wildlife Refuge System and Ecological Services, New Mexico Game and Fish Department, New Mexico State Parks, New Mexico and Arizona Riparian Councils, and New Mexico and Arizona Partners in Flight have been looking to researchers to fill their needs for a scientific basis for managing range-riparian and urban-riparian zones, including managing for the controversial wildlife dimension. Phelps-Dodge Corporation, The Nature Conservancy and the U-Bar Ranch will also be cooperating with RWU 4351 on endangered species studies. These managers, private industry groups, and environmental organizations will use our research information to establish survey and monitoring protocols, update state and local species records, incorporate data into on-line data bases, classify species of priority for management, identify habitats and species in need of recovery, and implement restoration projects based on knowledge generated by researchers. Other research institutions that will be cooperating with RWU 4351 to implement research studies include University of New Mexico, New Mexico State University, Western New Mexico University, USGS-BRD Colorado Plateau, and UNM Natural Heritage Program.


Element 1. Determine how roads and stream channel realignments influence the hydrological and vegetation dynamics of riparian systems and evaluate road engineering techniques designed to repair damaged systems.

As a cooperative venture between the State of New Mexico, Cibola and McKinley Counties, the Federal Highway Administration, and the Cibola National Forest, reconstruction of FR 49 and 50 through the Zuni Mountains of New Mexico was initiated to provide all season access into the Cibola National Forest and help improve watershed conditions. Roadway and drainage structures were installed to make the roadway function as a part of the surrounding ecosystem. Special road-design features included raised culverts, French drains, multiple culverts spread across broad meadows, and road relocation. A channel realignment project implemented in the Agua Fria meadow, where FR 49 crosses, was designed to help increase soil moisture and colonization of the meadow by riparian plant species. Our studies will monitor hydrological processes and rock weir efficiency, by measuring precipitation, stream flow, soil moisture, and soil erosion using weather stations, soil moisture probes, and stream-flow gauges. Six transects, three above and three below the road, will be installed to monitor soil moisture and vegetation changes.

Element 2. Determine how the increasing presence of exotic woody plants affects the abundance, migration, and stopover habitat use of Neotropical migratory birds in riparian systems.

We will assess the value of native and exotic riparian habitats in southwestern grasslands as stopover and refueling sites for Neotropical migrants by establishing two master banding stations on the Rio Grande, one at the Bosque del Apache, near Socorro, NM and the other at the Rio Grande Nature Center in Albuquerque, NM. Twenty mist nests distributed in cottonwood, willow, salt cedar, Russian olive, and agricultural fields will be established at each station. Captured birds will be banded, weighed, and measured to distinguish species, subspecies, sex, and age. Subcutaneous fat deposits will be recorded in order to assess energy consumption status of individuals. To verify migrant numbers, point count stations will be established on transects in habitats similar to those at mist-net sites. Vegetation data from each net location and counting point will be collected using a modification of the Daubenmire method. Arthropod communities associated with native and exotic woody plants will be sampled at each net site to determine whether variation in migrant stopover use is related to variation inarthropod species composition and abundance.

Element 3. Investigate the factors that affect and inhibit reproduction, migration, and abundance of the endangered southwestern willow flycatcher, and develop methods to recover its populations.

Most current research efforts on willow flycatchers are restricted to the inventory and documentation of location, size, and habitat of breeding populations. Information on the flycatcher's migration, stopover biology, and habitat use during migration is mostly absent, yet spring and fall migrations are energetically-expensive periods of time that can account for up to one third of a migratory bird's annual cycle. To effectively conserve populations of the willow flycatcher, it is important to identify limiting factors associated with its migration. Our approach for studying the migration of the willow flycatcher is the same as that described for Neotropical migratory birds in Problem 2, Element 2 with the exception that additional mist nets will be added in mowed and unmowed willow sites to evaluate effects of willow removal on flycatcher use of stopover habitats.

To identify causes of population decline of the flycatcher, information on population size must be coupled with data on the demographic composition of the flycatcher population. Data on nesting success, yearly recruitment rate, survivorship, sex ratio, and age distribution can provide valuable cues in distinguishing factors or events regulating a population. The largest population of the flycatcher resides on private property adjacent to the Gila National Forest, near Silver City, NM. This private land is considered to contain a flycatcher source population that with help may have the potential to colonize riparian areas on the Gila National Forest and elsewhere. An agreement to conduct research on the flycatcher has been established with the U-Bar Ranch that leases the land to graze cattle. Flycatchers and other bird species will be spot-mapped on different-sized patches of riparian habitat. Following spot-mapping, nests will be located, and nest contents will be recorded and monitored until nestlings fledge or the nest fails. Nest site characteristics and local habitats will be measured to determine differences between sites used by flycatchers and unused sites. We will evaluate the effects of brood parasitism by the brown-headed cowbird on breeding success of the willow flycatcher by monitoring presence and outcome of cowbird and host eggs in flycatcher nests. Host-cowbird interactions will be studied in relation to plant community type, vegetation structure, local conditions, and habitat improvement efforts to determine if habitat restoration practices will influence nest detection and parasitism rates by cowbirds. The influence of livestock presence and grazing on habitat structure, composition, and succession of riparian habitats will be assessed and related to the population assessments of flycatchers and cowbirds.



To order click here: Proceedings RMRS-P-3  

To order click here: RMRS-GTR-16

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