Nevada Desert FACE Facility (NDFF) Research: Biotic Processes Regulating the Carbon Balance of Desert Ecosystems

Co-PIs: Lynn Fenstermaker and J. Arnone, DRI; R. Nowak, UNR; S. Smith, UNLV

Project Period: October 2000 - September 2007

Funded by: DOE Terrestrial Carbon Processes Program

Figure 1 (right): This is a picture of one of the elevated (FACE) CO2 rings. The center pivot platform is used by researchers to gain access to any location within the plot. Use of the platform prevents disturbance/destruction of the soil microbiotic crust, an important source of nutrients in desert systems. Photo acquired by Lynn Fenstermaker and Eric Knight using a radio controlled helicopter.

Keywords: global climate change, desert ecology and ecophysiology, remote sensing, field spectra

Project Description

The NDFF consists of 9 study plots, each 23 m in diameter: 3 FACE rings at elevated CO₂ concentration (550 PPM), 3 FACE rings at ambient CO₂ concentration (i.e. control rings at ambient CO₂ concentration of 360 PPM ), and 3 non-blower control plots. The array of study plots is located on a broad alluvial fan in vegetation that is dominated by Ambrosia dumosa (bursage) a small drought-deciduous shrub, and Larrea tridentata (creosotebush), an evergreen shrub that reaches over 1 m in height. Other important shrubs include the drought-deciduous Lycium andersonii (Anderson's wolfberry), Lycium pallidum (pale wolfberry) and Krameria erecta (desert ratany) and the evergreen Ephedra nevadensis (Mormon tea). Abundant perennial grasses are: Achnatherum hymenoides (Indian ricegrass), Pleuraphis rigida (big galleta), and Erioneuron pulchellum (fluffgrass). Up to 75 annual species may occur depending on rainfall, including the exotic annual grass Bromus madritensis ssp. rubens (red brome). Soils at the site have a well-developed microbiotic crust made up of bacteria, algae, mosses and lichens that makes atmospheric nitrogen available to organisms by a process known as fixation

The NDFF is the first and only FACE facility in the world that is located in a desert ecosystem, and thus serves as the model for desert ecosystems around the world. Nevada Desert FACE is especially relevant to desertification, which is a major land use problem in North America as well as globally.

The primary overarching goals of the NDFF research are:

1. Leaf- to Plant-Level Responses of Desert Vegetation to Elevated CO₂.
   Investigate the first and second order effects of increased atmospheric CO₂ concentration on the physiological processes of photosynthesis, allocation of carbon and other resources, shoot and root growth, and plant water relations in desert species with contrasting growth form, phenology, and photosynthetic pathways.
2. Ecosystem-Level Responses to Elevated CO₂.
   Determine the effect of elevated CO₂ on ecosystem-level processes such as carbon gain, productivity, water use and landscape water balance, nutrient uptake and cycling, and plant competition for resources that may result in community structure changes.
3. Build Predictive Models of Plant and Ecosystem Responses to Elevated CO₂.
   Integration between experimental ecology and modeling to simulate the temporal and spatial behavior of desert ecosystems and allow predictions of responses to a range of global changes including elevated CO₂.

For more information about the NDFF, please visit the NDFF website at: http://www.unlv.edu/Climate_Change_Research/.

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