FT 5 - A Day on the Blackland Prairie:  Changes Wrought by Rising Atmospheric CO2 Concentration, the Proliferation of Exotic Plants, and Land Use Changes

Saturday, August 6, 2011: 8:00 AM-1:00 PM
Trinity Street Lobby Field Trip Pick Up, Austin Convention Center
Organizers: H. Wayne Polley , Philip A. Fay and Brian J. Wilsey
Participants will view and discuss results from three long-term and two new field experiments in the Blackland Prairie region of central Texas, all located at the Grassland, Soil & Water Research Laboratory (Blackland Research Station) in Temple, TX. In the Lysimeter CO2 Gradient (LYCOG) experiment, we utilize unique, elongated chambers to expose tallgrass prairie vegetation to a continuous gradient in atmospheric CO2 spanning pre-Industrial to elevated levels. This experiment is providing insight into how changes in net primary productivity associated with CO2 enrichment are coupled with changes in plant species composition and carbon cycling. The Maintenance of Exotic vs Native Diversity (MEND) experiment consists of plots planted to all exotic or all native grassland species. Most former prairie in the region have been replaced by mixtures of exotic herbaceous species with a variety of geographic origins (Asia, South America, Africa, Europe). The MEND experiment is designed to test the hypothesis that species diversity is lower in exotic than native communities because niche partitioning is smaller among evolutionarily-naïve exotics than co-evolved native species. The Nutrient Network (NutNet) Experiment is located within one of the few remaining remnants of never-plowed Blackland prairie in Texas. The NutNet experiment at Temple is one of 50 identical experiments globally and is designed to test effects of element additions on grassland net primary productivity and plant community composition. We are also selectively removing the dominant invasive plant in the system (Sorghum halapense, Johnsongrass) to test the hypothesis that Johnsongrass outcompetes native species for nitrogen. The Long-term Biomass Experiment is located adjacent to the remnant prairie, and consists of twenty-four 0.8 acre/0.32 hectare plots planted to either a mix of native tallgrass prairie grasses and forbs or to monocultures of perennial grasses, either the biofuel feedstock candidate switchgrass (Panicum virgatum L. cv. ‘Alamo’) or the forage grass bermudagrass (Cynodon dactylon cv ‘Coastal’). We are testing the hypothesis that the mixed species prairie assemblage wil show less interannual variation in aboveground biomass production than the monocultures, while providing additional important ecosystem services. Finally, in the Switchgrass Precipitation Variability experiment, we are exposing ten populations of Panicum virgatum to a range of precipitation variability treatments. The populations were chosen to span varying ploidy levels and geographic origins, and are being evaluated for their physiological, ecological, and gene expression responses to varying precipitation regimes. This experiment will provide data on the potential success of these lines under future precipitation scenarios.

Registration Fee: $50

Equipment and Attire: Be prepared for hot temperatures. Minimal walking wil be required over mostly smooth terrain. Hats and adequate drinking water are recommended. A shade canopy will be provided.

Itinerary: The entire site visit should take no more 2-3 hrs. The site is located near Temple, TX, approximately 1 hr driving time from central Austin. It is recommended that participants arrive relatively early in the morning (depart Austin at 8:00-9:00 am) so that the field portion of the trip can be completed before mid-afternoon when temperatures typically are warmest.

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Banner photo by Flickr user greg westfall.