Summary
Current Research
- Differences in Physiological Responses to Soil Water Availability between Partially Top-Killed and Untreated Mesquites (Duration: 2017 – Present)
- Will Not-Target Shrub Species become Collateral Damage Following Mesquite Spraying? (Duration: 2017 – Present)
- Comparison of various practices to control Texas Wintergrass in North-Central Texas (Duration: 2018 – Present)
The Rangeland Ecophysiology research program aims to improve the understanding of leaf-, plant-, and stand-level physiological processes in rangeland settings. A greater understanding of the bio-physical mechanisms behind the interactions between plants, soils, the abiotic environment, livestock, and wildlife enhances our ability to predict how vegetation will respond to future changes in climate and land management.
Specific program objectives include:
- Identify physiological and morphological adaptations woody plants use to sustain themselves in order to develop management guidelines that more effectively address these adaptations in initial and follow-up treatments.
- Ascertain the effects shifts in woody plant physiology and morphology may have on soil moisture, nutrient processes, and grass production and how these may interact with climate variability.
- Evaluate how modifications in range and pasture management may be used to enhance ecosystem services.
Differences in Physiological Responses to Soil Water Availability between Partially Top-Killed and Untreated Mesquites (Duration: 2017 – Present)
Research will determine the impacts of partial top-killing from herbicide on mesquite (Prosopis glandulosa) physiology (gas exchange and leaf pressure-volume characteristics). Since partially top-killed mesquites have reduced leaf areas compared to roots and sapwood area, stress coping mechanisms likely differ from untreated mesquites. Results will be used to develop recommendations for follow-up brush treatments.
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- Dr. Caitlyn Cooper measures photosynthesis rates and water loss from mesquite leaves with an open-flow gas exchange system.
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- Partially top-killed mesquites in a plot sprayed with herbicide in 2015
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- Tian Zhang taking pressure-volume curve measurements to assess mesquite water-stress responses.
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- Tian Zhang measures gas exchange from a mesquite partially-top killed by herbicide.
Will Not-Target Shrub Species become Collateral Damage Following Mesquite Spraying? (Duration: 2017 – Present)
This research project explores the causes of lotebush (Ziziphus obtusifolia) defoliation and mortality following the aerial application of herbicide to kill mesquites (Prosopis glandulosa).
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- A walking stick finds cover among similarly-colored mesquite foliage.
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- Prairie rattlesnake moving through grass at the Smith-Walker Research Unit.
Preliminary observations suggest herbaceous insects are likely the cause of lotebush decline following large-scale mortality of mesquite. More detailed observations documenting the quantities and types of insects feeding on lotebush are needed along with the peak time of damage.
We hypothesize that foliar herbivores and/or wood-boring insects that previously fed largely on mesquites have switched to an alternative food source following mesquite death after herbicide spraying.
Comparison of various practices to control Texas Wintergrass in North-Central Texas (Duration: 2018 – Present)
This research will examine the effects of various treatment practices (grazing at high stock density, herbicide application, grazing + herbicide application) and treatment timing on Texas Wintergrass (Nassella leucotricha) growth, density, and seed production.
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- Cows entering the enclosure to graze Texas wintergrass.
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- Evaluating herbage removal following a grazing event.
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- Evaluating herbage removal following mowing.
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- Cows exiting the enclosure after a job well done!
Additional measurements will include monitoring changes in soil moisture and bulk density, habitat structure, and herbaceous species composition.
Project goals are to find effective management practices to manage Texas Wintergrass and promote the establishment of native, warm-season perennial grasses. Research will be conducted with researchers from Texas A&M AgriLife Research – Stephenville and a graduate student from Tarleton State University.
Dr. Richard Vierling, Center Director
Center Director
(940) 647-3894
Please contact Dr. Vierling with questions about this project.
Team Members
Publications
Aparecido LMT, Cooper CE, Ford-Miniat C, Moore GW. In prep. Comparison of radial variability of sap flow between tropical and temperate trees with deep sapwood. Target journal: Tree Physiology.
Cooper CE,Vogel JG, Muir JP, Moore GW. In prep. Physiological responses to prolonged drought differ among three oak (Quercus) species. Target journal: Physiologia Plantarum.
Cooper CE, Aparecido LMT, Muir JP, Morgan CLS, Moore GW. In review. Comparison of transpiration across burn severities in recovering mixed loblolly pine and oak stands in the Lost Pines region of Texas. Tree Physiology.
Cooper CE, Muir JP, Morgan CLS, Moore GW. 2018. Tortoise or hare: will resprouting oaks or reseeding pines dominate following severe wildfire? Forest Ecology and Management 408:54-66.
Naumann HD, Cooper CE, Muir JP. 2017. Seasonality affects leaf nutrient and condensed tannin concentration in southern African savanna browse. African Journal of Ecology 55: 168-175. DOI:10.1111/aje.12336
Cooper CE, Naumann HD, Lambert BD, Muir JP, Kattes DH. 2014. Legume protein precipitable phenolic and nutrient concentration responses to defoliation and ontogeny. Journal of Plant Interactions 9:468-477.
Grants
- Grant #1