Current Research Projects

Extreme Drought in Grasslands Experiment

The  goal of EDGE is to determine the consequences of chronic drought on biodiversity and ecosystem services in grasslands across precipitation and temperature gradients in central North America. Principal Investigators at UNM are Scott Collins and Will Pockman. This is a collaborative research project led by Alan Knapp and Melinda Smith (Colorado State University) and Yiqi Luo (University of Oklahoma).

The role of ecological heterogeneity in a long-term grassland restoration experiment

Many aspects of plant community structure and ecosystem functioning have been degraded by human disturbance to the environment, and may not return without human intervention through ecological restoration. Restoring biodiversity in disturbed ecosystems is a nearly-universal challenge, as well as an opportunity to test general ecological principles about species coexistence. This project extends an on-going 14-year test of whether heterogeneity in the environment creates vacancies and accessible resources that allow new species to establish and coexist in a community.

Long-term Ecological Dynamics (LTED)

Ecological communities are highly dynamic in space and time. Analysis of spatial variability has a long history in ecology, yet because of the historical dearth of long-term, well-documented, on-line datasets we know comparatively little about rates and patterns of temporal change in ecological communities. Fortunately, an expanding array of long-term datasets is now available through sources such as the LTER Network and LTREB program.

Sevilleta LTER: Abiotic pulses and constraints: effects on dynamics and stability in an aridland ecosystem

Our LTER research integrates studies on multiple global change drivers and pulse precipitation dynamics to determine how they affect the rate at which this grass- to shrubland transition occurs. Together, our research across multiple time and space scales is yielding a comprehensive understanding of how key abiotic drivers affect pattern and process in aridland ecosystems.

Warming, El Niño, Nitrogen Deposition Experiment (WENNDEx)

Humans are causing significant global environmental changes, including warmer temperatures, increased atmospheric nitrogen (N) deposition, and more frequent and intense El Nino events. Although each of these factors can have major impacts on plant community composition and ecosystem processes, it is not known how these factors will interact to affect ecosystem dynamics in the future. Furthermore, although arid and semiarid systems cover approximately a third of the earth’s surface, few experimental warming studies have been conducted in these systems. We are conducting a multi-factorial global change field experiment in an arid grassland community at the Sevilleta.

Convergence and contingencies in savanna grasslands

Savanna grassland distribution, structure and function are a product of three interacting drivers - fire, grazing by large herbivores, and extreme climatic fluctuations. Although all savanna grasslands share these drivers, evidence suggests that fire and grazing affect ecosystem structure and function in fundamentally different ways in southern Africa (South Africa (SA), in particular) and North America (NA).

Do vegetation-microclimate feedbacks promote shrub encroachment in the Southwestern United States?

Woody plant encroachment into grasslands is a global phenomenon that results from a variety of global change drivers. Over the last 150 years the southwestern US has undergone dramatic changes in the composition and structure of vegetation due to range expansion by Larrea and Prosopis spp.

Monsoon Rainfall Manipulation Experiment (MRME)

The objective of the Monsoon Rainfall Manipulation Experiment (MRME) is to understand changes in ecosystem structure and function of semiarid grassland caused by increased precipitation variability, which alters the pulses of soil moisture that drive primary productivity, community composition and ecosystem functioning. The overarching hypothesis being tested is that changes in event size and variability will have differential effects on grassland dynamics and creosote invasion of desert grassland.

The effect of resource addition on plant community structure in desert grassland.

Aridland ecosystems are strongly limited by water availability and potentially by nitrogen availability, as well. The unimodal model of productivity and species diversity predicts that diversity will increase with productivity in low productivity systems such as desert grasslands. We analyzed the relationship between aboveground net primary production (ANPP), species diversity and climate variability in a long-term nitrogen fertilization experiment in low productivity desert grassland at the Sevilleta.

The effect of multiple resource additions on community structure and ecosystem processes.

The Sevilleta LTER is a participant in the Nutrient Network (NutNet).