Since 1989, the Sevilleta Long-Term Ecological Research Program (SEV LTER) has conducted long-term observations and experiments to understand the factors that control the ecology of semi-arid ecosystems (photo 1), including grasslands, shrublands, woodlands, the forests that line the Rio Grande, and in the transitions between these ecosystems where they intersect in central New Mexico (photo 2). We study how the growth and activity of plant species in each of these communities responds to variation and change in the physical environment, the influence of plant growth, flowering and seed production on associated animal communities, the role of microbes in soils and plants, particularly understudied desert ascomycetes, and the response of these ecosystems to disturbances such as fire or climate extremes (drought, severe freezing).  During the first 30 years of the project, examples of key SEV LTER measurements and the resulting advances in ecological knowledge that could only be obtained through long-term monitoring and experimentation include:

1) Long-term measurements of growth, productivity and reproduction of key species in multiple ecosystems captured the response of these species as growing conditions change over time.  Comparison of these data with long-term records of temperature and precipitation allowed SEV LTER researchers to advance our knowledge of the role of long-term weather patterns like El Ni?o and La Ni?a in controlling the growth and reproduction of plants in these ecosystems.

2) Long-term measurements of populations of small mammals at multiple sites spanning key regional ecosystems captured how rodent population cycles are related to variation in environment (temperature and precipitation) and vegetation productivity and reproduction.  These data, together with museum specimens of key rodent species collected over time, were used to help reveal the ecological context and identity of Hanta virus in the southwestern US when it emerged as an unknown disease in the Four Corners region.

3) Long-term experiments at SEV LTER have imposed changes in growing conditions (temperature and precipitation) or vegetation structure, coupled with long-term measurements to understand the impact of these manipulations as they unfold through a period of years.  Coupled with long-term observations of biological function under climate variability and change, these experiments allow us to understand the impacts climate conditions that cannot be assumed to occur during the period of a standard research grant.  These experiments have advanced our understanding of the response mechanisms of grasses (photo 3), shrubs and trees during severe drought, the changes in grassland vegetation when warming and precipitation interact, and the impact of changes to summer precipitation in the region on grassland communities (photo 4). 

4) Using eddy covariance methods (photo 5), large-scale long-term measurements of the uptake and release of CO₂ provides a cumulative record across ecosystems that are representative of large areas of the southwestern US.  These data have revealed the role of within-season versus between-season climate fluctuation on the storage of carbon in semi-arid ecosystems.

5) Combining long-term observations and experiments, SEV LTER has tested the long-standing idea in ecology that the many aspects of ecosystem activity in arid lands are governed by the size, frequency, and intensity of rainfall events (the pulse-reserve hypothesis of Noy-Meir), which generate activity by adding water to the ecosystem.  SEV research revised the focus of this idea from the role of single rainfall events, to the importance of year-to-year variation in the sequence of pulses, an area of study that is ongoing. 

As the breadth and impact of SEV research have expanded (over 800 publications cited more than 61,000 times according to Google Scholar), SEV LTER has contributed to training generations of young scientists through graduate research (more than 80 masters and doctoral students), undergraduate mentoring (including an NSF Research Experiences for Undergraduates program) and through our Schoolyard LTER, the Bosque Environmental Monitoring Program (BEMP). BEMP brings K-12 students from schools along the Rio Grande to local sites where students collect long-term data describing the state and function of this landmark ecosystem of the western US.  Now serving more than 10,000 community members per year, BEMP has been successful for so long that students who began their participation in grade school are now continuing their involvement as undergraduate and graduate students at the University of New Mexico. 

During the 3-year period of this final award that ended the first phase of the Sevilleta LTER, our proposal to work at the same site won a competitive external review process for a new LTER site. This new award extends the long-term data collection from the past and addresses a novel set of research questions, enabling a continuous record of the structure and function of the ecosystems that represent key ecological transitions in drylands and continuing the legacy of BEMP?s contributions to community science and science literacy.

Last Modified: 12/31/2019
Modified by: William T Pockman