Experimental mesocosm are being used at the Konza Prairie to simulate future climate conditions projected to occur in the Midwest, USA. These large outdoor experiments provide realistic context for manipulations of precipitation patterns, increased air temperatures, and simulated droughts.

Large outdoor facilities like mesocosms allow for complete manipulation of the physical environment to match climate change predictions, automation of sensor networks, and organismal, community, and ecosystem ecological research in a natural setting. This approach provides more realism and has many advantages over laboratory studies, or small-plot field research.

At present, there are two current mesocosm facilities and one pending facility. The RaMPs facility was established in 1997 to manipulate the role of altered patterns of precipiation on tallgrass communities, The aboveground mesocosms were established in 2003 to alter both rainfall patterns and amount in a factorial matrix.

The RaMPs Project:

The microclimate beneath the rainout shelters is characterized in four rainfall manipulation shelters and in an unsheltered control plot. Measurements of PFD are made with a quantum sensor (LI-190SB), and net radiation with a Fritschen-type net radiometer.  Soil, air (shielded, aspirated), and stored water temperatures are measured with thermisters.  Radiation and air temperature sensors are mounted in the center of the plot, 1.5 m above ground level.  To characterize the warming treatments, thermisters or thermocouples are buried at 2, 5 and 15cm in warmed and ambient subplots, and canopy temperatures are monitored with infrared thermometers.  Sensor outputs are recorded on Campbell CR10X data loggers. Temporal patterns of soil water content are measured weekly using time domain reflectometry. Stainless steel probes are inserted to 15 and 30 cm depths in each heated and unheated subplot, and moisture content determinations are made with a Tektronix 1502B cable tester.

This experiment provides a novel platfrom to measure changes in the tallgrass prairie from the simulated effects of key constructs of global climate change: altered precipiation patterns and elevated air temperatures.Using the 10-year dataset measuring these effects, multiple investigators are presently relating changes seen at the organismal, community and ecosystem level to environmental alterations mimicing projected climate changes.

An individual shelter in the RaMPs. Black containers contain stored rainfall.

The mesocosms were established by Dr. Phil Fay (USDA-ARS, Temple, TX), and initally funded by the NSF. This facility contains 64 seperate containers arranged in two banks of 32 (2 x 16). The containers are 1.2 m x 1.2 m with a depth of 1.8 m (2.6 m³). They are constructed of 12 mm plywood lined with 0.15 mm polyethylene. These dimensions provide a large soil volume for root development, and allow for a 1.0 x 1.0 m central sampling area where soil attributes and above- and belowground plant responses can be measured without edge effects from the mesocosm walls. The containers have a perforated floor lined with root cloth to allow drainage but contain long roots.  Each mesocosm has a bottom layer (1.5 m) of heavier clay soils and an upper soil layer consisting of 0.3 m of topsoil; soil was excavated in the respective locations in the surrounding prairie and emulates the soil organic matter, nutrient, and textural profiles found on deep-soiled lowlands (P. Fay, personal observation).  The containers were built 50 cm below grade to lessen unrealistic soil temperature variation.

Each mesocosm container is equipped with automated soil moisture probes (TDR-100) to measure volumetric water content in the top 30-cm and a mini-rhizotron access tube to measure root turnover and productivity. In the spring, 2008 a new factorial experiment is planned where Panicum virgatum genotypes collected from relic tallgrass prairie in the central Great Plains will be grown in a common garden. This project is a collaborative venture with Dr. Clint Springer (St Joseph's University) and Phil Fay to examine the physiological and genotypic responses (similarities and differences) of a common dominant plant species to environmental variability predicted to occur in this region in the future.

This proposed research is a collaborative project with Dr. Melinda Smith (Yale University) submitted to NSF-DEB during the summer 2007. This research will examine the relationships between genetic and species biodiversity within the context of climate change. Specific objectives are to elucidate how genetic and species diversity interact within communities and the mechanisms underlying these interactions, to evaluate how changes in genetic and species diversity impact ecosystem-level processes, and to examine how each component of diversity responds to altered precipitation amount and variability.

To accomplish these objectives we will build a new belowground mesocosm facility consisting of two arrays of 46 1.2 x 1.2-m containers (92 total). Each container will be at ground-level, and lined with steel flashing on 4 sides to bedrock. A retractable roof will cover this facility during rainfall events, with stored rainfall available for application as per specific treatments. This experiment will have a factorial design of 3 levels of genetic diversity, 3 levels of species diversity, and 3 precipitation manipulations (ambient, 50% increase in variability, 30% decrease in amount). Pending funding, construction of this facility will begin Fall, 2008.