Simulating diverse native C4 perennial grasses with varying rainfall

Authors: KIM, SUMIN - Oak Ridge Institute For Science And Education (ORISE); Williams, Amber; Kiniry, James; HAWKES, CHRISTINE - University Of Texas

Submitted to: Journal of Arid Environments
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 7/18/2016
Publication Date: 7/29/2016
Publication URL: https://handle.nal.usda.gov/10113/5321006
Citation: Kim, S., Williams, A.S., Kiniry, J.R., Hawkes, C.V. 2016. Simulating diverse native C4 perennial grasses with varying rainfall. Journal of Arid Environments. 134:97-103. http://dx.doi.org/10.1016/j.jaridenv.2016.07.004.
DOI: https://doi.org/10.1016/j.jaridenv.2016.07.004

Interpretive Summary: Rainfall is a major factor affecting the rate of plant growth. Changes in amount and variability of rainfall on growth of different grasses need to be quantified to determine how climate change impacts rangelands. Growth varies among forage species under different rainfall patterns. Studies comparing growth of several grass species with different rainfall will provide useful information for identifying forage management strategies under various rainfall scenarios. In this study, we studied the effects of combinations of rainfall changes and soil types on plant growth of 10 grass species. We used both experimental methods, using rainout shelters, and numerical methods using the plant growth simulation model, ALMANAC. Most species increased measured diameter of the stem and height as rainfall increased. Different size leaf area groups varied in their plant volumes with various rainfall rates. Short prairie grasses such as purple three-awn, Hall’s panicum, sideoats grama, indian grasses, and tall dropseed were more tolerant of lower rainfall, while plant growth was greatly reduced for tall plants such as switchgrass. The simulated yield also varied among leaf area groups. Simulating all species growing together competing agrees relatively well with observed volumes at low rainfall treatment, while simulating all species growing separately was slightly biased towards overestimation of growth on low rainfall effect. Both simulations agree relatively well with observed volume measurement at high rainfall treatment.

Technical Abstract: Rainfall is recognized as a major factor affecting the rate of plant growth development. The impact of changes in amount and variability of rainfall on growth and production of different forage grasses needs to be quantified to determine how climate change can impact rangelands. Growth and production varies among forage species under different rainfall patterns. Comparative studies to evaluate the growth of several perennial forage species at different rainfall rates will provide useful information by identifying forage management strategies under various rainfall scenarios. In this study, the combination of rainfall changes and soil types on the plant growth of 10 perennial forage species was investigated with both the experimental methods, using rainout shelters, and with the numerical methods using the plant growth simulation model, ALMANAC. Overall, most species significantly increased basal diameter and height as rainfall increased. Different size LAI groups varied in their plant volumes with various rainfall rates. Low and Mid LAI prairie grasses such as purple three-awn, Hall’s panicum, sideoats grama, indian grasses, and tall dropseed were more tolerant of lower rainfall, while plant growth was greatly reduced for High LAI grasses such as switchgrass. The simulated yield also varied among LAI groups. Simulating all species growing together competing agrees relatively well with observed volumes at low rainfall treatment, while simulating all species growing separately was slightly biased towards overestimation on low rainfall effect. Both simulations agree relatively well with observed volume at high rainfall treatment.