Current Research Projects

There has been little comprehensive research undertaken to quantify resource use by small mammal communities in a nutrient limited, highly stochastic ecosystem. The most abundant small mammals in this ecosystem are Heteromyids, food-caching granivores, and Cricetids, omnivores that must utilize on board fat stores as energy reserves.

The Sevilleta Gunnison’s Prairie Dog (Cynomys gunnisoni) Relocation project examines keystone consumer (herbivore) effects on grassland in concert with ecological restoration of a “species of greatest conservation need in New Mexico” (NMG&F Comprehensive Wildlife Conservation Strategy, 2007).

Ant colonies possess a “societal metabolism,” acquiring, transforming, and allocating resources through a network of foragers (Moses, 2005). Ant foraging- trail networks channel foragers to known food resources and away from competing colonies (Jun et al., 2003). Computer models suggest the spread of information occurs faster in larger colonies of harvester ants, genus Pogonomyrmex (Adler and Gordon, 1992), providing a possible mechanism of differentiation.

This file contains hourly time-domain reflectometry (TDR) soil moisture data for 1996-2005. A key factor in a spatially explicit water-balance model is a measure of moisture in the soils over time. This metric is crucial for both calibration and validation of such a model. One of the best methods of measuring soil moisture on a continuous basis is TDR. Therefore, a network of TDR soil moisture sensors was installed at all meteorological stations on the Sevilleta National Wildlife Refuge.

The primary objective of this study is to examine the control that substrate quality and climate have on patterns of long-term decomposition and nitrogen accumulation in above- and below-ground fine litter. Of particular interest will be to examine the degree these two factors control the formation of stable organic matter and nitrogen after extensive decay.

This dataset contains weights of vegetation biomass collected in fertilizer plots from 1989 through 1992. The data were originally collected to analyze the effects of fertilization on vegetation productivity on the Sevilleta NWR.

From March 2005-Februaury 2009, a population of banner-tailed kangaroo rats was monitored  using mark-recapture methods. All active kangaroo rat mounds on the 18-ha Nunn Flats site were trapped monthly. All captured individuals were marked and reproductive status and mass were recorded. From February to July 2008 a subset of adult females received supplemental food.

Phenology is the study of recurring natural phenomena. The seasonal "greening-up" and "greening-down" of dominant vegetation can be used as a predictor for a variety of processes and variables at local to global scales. The use of satellites to monitor land surface phenology is important for understanding local and regional ecosystem variability, identifying change over time, and potentially predicting ecosystem response to short and long-term changes in climate.

Previous morphological work on lizards suggests that the volume of growing eggs may result in a significant decrease in lung volume during gravidity. Iguanid lizard lungs are located within continuous thoracic and abdominal cavities and are highly distensible. Because of their distensible nature and lack of a diaphragm, both naturally occurring and introduced structures within the abdominal and thoracic cavities (i.e.

The Rio Grande is well-studied as a regionally important water source, but the small, poorly characterized springs that surface within the Rio Grande rift are also a vital resource. Several of these springs have water chemistries that suggest a mixing of larger volume meteoric recharge with small volume, deeply-sourced fluids.

Grazers and granivores have the potential to affect seed banks. Several studies have examined the impact of these herbivores on the aboveground vegetation, but few have looked at how they influence the seed bank. I asked whether both grazers and granivores alter the seed bank at the Sevilleta National Wildlife Refuge. Long-term experimental plots were installed in 1996 to exclude grazers and granivores from a grassland and shrubland.

Disturbance is a major factor in determining the spatial structure and temporal dynamics of ecological systems. Many studies have been conducted concerning the plant assemblages around Dipodmys spectabilis mounds compared to the off mound area. These studies have shown that annual plant cover is higher on the kangaroo rat mound compared to off the mound. However, no studies have addressed the effects of these rodents disturbance on the soil seed bank.

The line-intercept transects included in this data set have been discontinued. These transects were installed to evaluate temporal and spatial dynamics in vegetation transition zones ( grama grassland/creosote shrubland) at one centimeter resolution. Each study site originally contained four 400 m transects, representing total coverage of 1 sq km. The transects were placed along a roughly north/south azimuth.

This file contains daily lightning activity data for the state of New Mexico. These data were collected by a network of lightning detection stations scattered throughout the western United States. More information regarding the LLP Lightning Locating System can be found in Maier et al. (1983).

We studied the diversity of arbuscular mycorrhizal fungi (AMF) in a semiarid grassland and the effect of long-term nitrogen (N) fertilization on this fungal community. Root samples of Bouteloua gracilis were collected at the Sevilleta National Wildlife Refuge (New Mexico, USA) from control and N-amended plots that have been fertilized since 1995. Small subunit rDNA was amplified using AMF specific primers NS31 and AM1.

Animal consumers have important roles in ecosystems, determining plant species composition and structure, regulating rates of plant production and nutrients, and altering soil structure and chemistry. The purpose of this study is to determine whether or not the activities of small mammals regulate plant community structure, plant species diversity, and spatial vegetation patterns in Chihuahuan Desert shrublands and grasslands.

The allometric ant foraging data was collected to test the allometric ant foraging model proposed by Jun et al. (2003). Key variables are the number of foragers in the colony, the time of an average foraging trip for the colony and the average distance a forager travels to collect a seed. Data on Pogonomyrmex rugosus and Pogonomyrmex maricopa were collected at the Sevilleta.

Data on soil characteristics and dominant grass and soil chemical composition gathered on active rangeland, livestock exclosures on active rangeland, and the Sevilleta NWR.

In order to better understand the life history of Ocotillo, a re-sampling of Ocotillo plants originally marked and studied in 1991 was done in the southeast corner of the Sevilleta National Wildlife Refuge. All plants measured in 1991 were re-censused and re-tagged with new numbers.

Maintaining high rates of water loss during times of high resource availability could allow establishing woody desert perennials to grow quickly by allowing them to take advantage of the fleeting but abundant monsoonal moisture typical of warm deserts like the Chihuahuan.

Because grasses and shrubs may induce different spatial distributions of nutrients in desert soils, this study was initiated to examine the redistribution of nitrogen in grassland and shrubland soils over a long time period.

Vegetation throughout the southwestern United States has changed from perennial grassland to woody shrubland over the past century. Previous studies on the development of 'islands of fertility' focused primarily on only the most limiting, plant-essential element, soil nitrogen (N).

In 1984, a research project was initiated on a relatively small disturbance patch just south of Deep Well. This disturbance was thought to be the result of an old praire dog town, probably dating back to when a nearby ranch was active, and a lot of old mammal mounds remained in the disturbed area.

This study examined concentrations of organic and inorganic phosphorus in surface soils of a Bouteloua gracilis-Bouteloua eriopoda grassland and a Larrea tridentata shrubland in the northern Chihuahuan Desert, New Mexico, USA. In this desert, where grassland vegetation has a uniform spatial distribution and individual shrubs have a patchy distribution, vegetation strongly influences the locations and concentrations of soil nutrients.

Plant cover estimates were collected from Bouteloua grasslands at 3 different LTER (SGS, SEV, JRN) sites in summer of 1996/1997. The purpose of the data collection was to compare species composition and diversity between LTER sites and sandy grassland sites in Hungary.

Our objective was to evaluate the effects of burrowing activities by banner-tail kangaroo rats (Dipodomys spectabilis Merriam) on plant community structure and species dominance for two patch types at an ecotone between shortgrass steppe and desert grasslands in New Mexico, USA.

This study measured the population dynamics of coyotes in the grasslands and creosote shrublands of McKenzie Flats, Sevilleta National Wildlife Refuge. The study was begun in January, 1992, and continued quarterly each year. Coyotes were sampled via scat counts along the roads of McKenzie Flats during winter, spring, summer, and fall of each year.

Responses of plant communities to mammalian herbivores vary widely, due to variation in plant species composition, herbivore densities, forage preferences, soils, and climate.

This database contains mean NDVI values for 200 m diameter circles encompassing Rodent Webs on the Sevilleta National Wildlife Refuge (NWR), for 21 Landsat TM scene dating from 1984 to 1993. These NDVI vectors were generated as part of cooperative project between the Sevilleta LTER and the Indian Health Service, to study the 1992 Hantavirus outbreak.

A natural burn occurred in the Deep Well area of McKenzie Flats in June, 1995, following which studies were initiated to evaluate the effect of fire on plant species composition and the spatial and temporal dynamics of regrowth. The burn area was approximately 24 hectares, forming a swath about 200 m wide from the initial lightning-ignition source.

Human populations in Colorado, New Mexico and Texas depend on the Rio Grande for municipal water, agricultural irrigation, and recreation. The Rio Grande and its riparian corridor also support thousands of species of plants, invertebrates and vertebrates, some of which include over 300 species of migratory birds and the endangered Rio Grande silvery minnow and southwestern willow flycatcher.

Grazing in grasslands creates changes in plant community structure. The magnitude of these changes depends on the productivity and the intensity of grazing.

The water balance vegetation plots were part of a larger water balance monitoring project at the Sevilleta LTER.

This file contains data collected from 1996-1999 at a Bowen ratio tower adjacent to the Deep Well Meteorological Station at Deep Well (Station 40). The Bowen ratio method employs a method of measuring the temperature and vapor pressure gradient over a vegetation canopy to quantify evapotranspiration from that canopy.

Plant communities across large portions of the southwestern United States have shifted from grassland to desert shrubland. Studies have demonstrated that soil nutrient resources become spatially more heterogeneous and are redistributed into islands of fertility with this shift in vegetation. This research addressed the additional question of whether soil resources become more temporally heterogeneous along a grassland-shrubland ecotome.

This study was designed to monitor the occurrence of various phenological events of plant species at seven research sites on the Sevilleta National Wildlife Refuge (i.e., Black Butte, Goat Draw, Five Points, Deep Well, Rio Salado, Sepultura Canyon and Los Pinos foothills watershed (Red Tank/222)).  The phenological events monitored included germination, vegetative growth, budding (flower

To support the hydrology studies in the Sierra Ladrones Study Basin, a network of moisture potential sensors and temperature sensors wereinstalled in the stream-channel sediments and adjacent soils atvarious locations up thru the watersheds in 1992.

This data set contains records for the numbers of selected groups of ground-dwelling arthropod species and individuals collected from pitfall traps at 4 sites on the Sevilleta NWR, including creotostebush shrubland, both black and blue grama grasslands, and a pinyon/juniper woodland. Data collections begin in May of 1989, and are represented by subsequent sample collections every 2 month

Keystone species have large impacts on community and ecosystem properties, and create important ecological interactions with other species.  Prairie dogs (Cynomys spp.) and banner-tailed kangaroo rats (Dipodomys spectabilis) are considered keystone species of grassland ecosystems, and create a mosaic of unique habitats on the landscape.

This project was designed to investigate the response of plant growth and reproduction to short- and long-term variation in biotic and abiotic environmental variables. Several perennial taxa, including tree (Juniperus monsperma and Pinus edulis), shrub (Larrea tridentata) and bunch grasses (Oryzopsis hymenoides (nowAchnaterum hymenoides) and Sporobolus contractus) species, were monitored at 1-3 sites differing in elevation and topography as well as edaphic variables and annual precipitation.

The litterfall study was designed to assess the quantity of biomass (leaves, twigs, reproductive materials) falling from tree species in different ecosystem types.

This project was designed to sample the richness and abundance of birds on the Sevilleta National Wildlife Refuge. Three types of habitat were surveyed: grassland, creosote shrubland and pinyon-juniper woodland.

The 100,000 ha Sevilleta National Wildlife Refuge (SNWR) in central New Mexico lies in a transition zone that straddles several major biomes of the Southwest, including Great Basin Shrub-Steppe, Mogollon Pinon-Juniper Woodland, Great Plains Grassland and Chihuahuan Desert.

The long-term goal of the decomposition study was to document the effects of climate variation on decomposition of major plant litter-types. The project began in 1989 and underwent changes of locations and litter types. The long-term litter types included black grama, Indian rice grass, juniper, and creosote.  Mass loss of the litter types can be compared to precipitation and other meteorological factors obtained at nearby locations.

Reptile populations were sampled in spring and summer in various habitats: grassland, creosote shrubland, pinyon-juniper woodland, cottonwood forest, subalpine forest, and subalpine meadow. On 18 sites mark-release methods were used; on 12 sites, all animals were kept for museum specimens.

Physiological status of plants is monitored in conjunction with the sampling schedule outlined in Sevilleta Plant Demography. Several perennial life forms, including tree (Juniperus and Pinus), shrub (Larrea) and grass (Oryzopsis and Sporobolus), are being monitored at 1-3 of four sites which differ in elevation and topography as well as edaphic and annual precipitation characteristics.

In this study, soil characteristics after a lightning-initiated fire were evaluated. Following the fire in July 1998, 25 experimental plots were established on the eastern edge of MacKenzie Flats at the Sevilleta National Wildlife Refuge. Ten of these plots were located in a Bouteloua gracilis (blue grama)-dominated site, while 15 were established in another area dominated by Bouteloua eriopoda (black grama).

Our objective was to evaluate the effects of kangaroo rat mounds on species diversity and composition at a semiarid-arid grassland ecotone. We expected that source populations of plants occurring on kangaroo rat mounds have important influences on species composition of vegetation at the landscape scale, and that these influences differ by grassland type.

Transition zones between biomes consist of a mosaic of patch types dominated or co-dominated by species from the adjacent biomes. Most studies of biome transition zones have focused on the dominant life forms or characteristic species, and patterns in subordinate species composition are not well documented and understood, yet it is these species that contribute to biodiversity.

This project addresses the idea that 1) structural and functional differences between shrubs and grasses are responsible for different short-term and long-term physiological and growth responses and 2) that these differences govern vegetation and hydrologic changes when grassland, shrubland and the transition (ecotone) ecosystems are subjected to climate extremes such as extended drought or prolonged periods of above-average precipitation.