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United States Department of Agriculture

Agricultural Research Service

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Location: Rangeland Resources Research

2012 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 primary collaborating scientist and his graduate student are working with ARS to increase our understanding of how establishment of plant seedlings is affected by global warming, rising atmospheric carbon dioxide (CO2), and altered precipitation, as part of a comprehensive research project predicting how western rangelands will respond to climate change. 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 from 2007, 2008, and 2009 were tested in the growth chamber/germination facility in the U.S. Studies evaluated how heating, CO2 enrichment and irrigation affected seed fill percentage, viability, seed mass, and germination. The graduate student used thermal and hydrothermal time models to identify temperature and water thresholds during germination, and linked these threshold parameters to properties of seeds produced under climate change conditions. Additional seeds from 2010, 2011 and 2012 have been sent to the collaborating scientist. Seeds from these three years will be tested this fall (2012) for additional evaluations on how climate change and CO2 affect seed quality. To ensure accountability of funds utilized, the ADODR holds telephone meetings at least every 6 months with the collaborating scientist and graduate student 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

Last Modified: 10/17/2017
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