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Location: Rangeland Resources Research

2011 Annual Report

1a. Objectives (from AD-416)
Determine germination thresholds of native and weed species from a Mixed-grass Prairie global change experiment.

1b. Approach (from AD-416)
Seeds from plants growing in the Prairie Heating and CO2 Enrichment Experiment will be collected and sent to the University of Saskatchewan. A suite of measurements/tests will be conducted, including: germination test for thermal time model, germination test for hydrothermal time model, seed viability, seed mass, seed C and N. Data will be analyzed, including the use of seed models to evaluate how elevated CO2 and warming affect seed/seedling physiology.

3. Progress Report
The University is working with ARS to increase our understanding of how establishment of plant seedlings is affected by global warming, rising CO2, and altered precipitation, as part of a comprehensive research project predicting how western rangelands will respond to climate change. A graduate student’s M.S. thesis research proposed to use thermal and hydrothermal time models to identify temperature and water thresholds during germination, and to link these threshold parameters to properties of seeds produced under climate change conditions. The objectives of this research are: 1) to identify the shifts in germination thresholds in selected species from the Mixed-grass Prairie as affected by global change conditions; and 2) to identify the physiological mechanisms for the shifts, extend the results to plant functioning groups and make general predictions on regeneration success of plants from not only grasslands but also other ecosystems. Seeds from native plants and invasive weeds produced in the Prairie Heating and CO2 Enrichment (PHACE) experiment were mailed to the graduate student in 2010, and studies commenced in the growth chamber/germination facility at the U.S. Studies evaluated how heating, CO2 enrichment and irrigation affected seed fill percentage, viability, seed mass, and germination. These results were incorporated into a thermal time model to better understand germination responses and to improve our ability to predict how global change will affect plant germination and population responses. Initial analyses and synthesis of this research was presented to graduate committee on June 30, 2011, and after recommendations on experimental and statistical procedures, the committee gave the graduate student the go-ahead to begin writing the M.S. thesis. A first draft of the thesis will be submitted to the graduate committee in September, 2011 for review. Corrections of the thesis are to be addressed in the fall and a final thesis, followed by a draft journal article is anticipated for the winter/spring of 2012. To ensure accountability of funds utilized, the ADODR holds telephone meetings at least every 6 months with collaborator to discuss research; staff of both groups communicates regularly via email on experimental protocols and information needed in the continued collection of seeds for possible future analyses.

4. Accomplishments