Digital Commons Network^™

Responses Of Extreme Discharge To Changes In Surface-Air And Dewpoint Temperatures In Utah: Seasonality And Mechanisms, Timothy E. Wright, Jacob Stuivenvolt-Allen, Grace Affram, Nahid A. Hasan, Cody Ratterman, Wei Zhang

Plants, Soils, and Climate Faculty Publications

The changes in stream discharge extremes due to temperature and seasonality are key metrics in assessing the effects of climate change on the hydrological cycle. While scaling is commonly applied to temperature and precipitation due to the physical connections between temperature and moisture (i.e., Clausius–Clapeyron), the scaling rate of stream discharge extremes to air and dewpoint temperatures has not been evaluated. To address this challenge, we assess the scaling rates between stream discharge and air temperature and between stream discharge and dewpoint temperature in Utah using a well-designed statistical framework. While there are deviations from the Clausius–Clapeyron (CC) relationship in …

Halotolerant Rhizosphere Bacteria: Isolation Of Rhizosphere Bacteria From Native Utah Plant Ceanothus Velutinus, Alyssa Nielsen

Fall Student Research Symposium 2021

Increasing incidences of drought forced farmers to use the secondary, degraded water for irrigation. These water sources are rich in salt concentrations. This project has started with the hopes of finding bacteria from the rhizosphere of a native to Utah plant, Ceanothus velutinus, that helps the plant survive the saltier conditions of Utah. The rhizosphere, a layer of soil attached to the roots of a plant, contains microorganisms that may contribute to the plants' abiotic and biotic stress resistance. These microorganisms are known as Plant Growth Promoting Rhizobacteria (PGPR). The roots and rhizosphere samples were collected from Tony Grove in …

Splitting The Difference: Heterogeneous Soil Moisture Availability Affects Aboveground And Belowground Reserve And Mass Allocation In Trembling Aspen, Ashley T. Hart, Morgane Merlin, Erin Wiley, Simon M. Landhäusser

Aspen Bibliography

When exploring the impact of resource availability on perennial plants, artificial treatments often apply conditions homogeneously across space and time, even though this rarely reflects conditions in natural systems. To investigate the effects of spatially heterogeneous soil moisture on morphological and physiological responses, trembling aspen (Populus tremuloides) saplings were used in a split-pot experiment. Following the division of the root systems, saplings were established for a full year and then subjected to either heterogeneous (portion of the root system exposed to non-lethal drought) or homogeneous (whole root system exposed to non-lethal drought or well-watered) treatments. Above- and belowground …

Microbial Community Of The Rhizosphere Of Ceanothus Velutinus Improves The Plant's Growth And Development Under Greenhouse Conditions, Jyothsna Ganesh

Student Research Symposium

Climatic change-induced environmental stresses affect crop production. Drought is such a stress which affect crop production and landscaping adversely. Native plants are great for low water use landscaping and can adapt to the natural environment. USU Center for Water-Efficient Landscaping has released a list of native plants that can be used for this purpose. This study focuses on a native plant Ceanothus velutinus (snowbrush) which is an evergreen plant native to western North America. It thrives well in harsh conditions and can act as ornamental plant in low water use landscaping but is difficult to propagate under landscape conditions. Here, …

Effects Of Thinning On Dynamics And Drought Resistance Of Aspen-White Spruce Mixtures: Results From Two Study Sites In Saskatchewan, Philip G. Comeau

Aspen Bibliography

Drought stress associated with warm temperatures is causing increased mortality and reduced growth of trees in drier portions of the boreal forests of western Canada with both warming and drought expected to increase over the coming decades. While thinning is often shown to reduce drought stress, there is little information on its effects in stands comprised of mixtures of trembling aspen and white spruce that are common in the forests of this region. This study examined effects of pre-commercial thinning on aspen and spruce growth, response to drought stress, and stand dynamics for two study sites located in Saskatchewan, Canada. …

Fruit Tree Responses To Water Stress: Automated Physiological Measurements And Rootstock Responses, William D. Wheeler

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

New orchard plantings utilize trees grafted to dwarfing rootstocks planted close together to facilitate larger harvests. These dwarfing rootstocks have not been comprehensively studied for their ability to withstand drought. This is of special importance in the Intermountain West which has limited rainfall. Additionally, orchard growers face competition for water from a growing population and increased uncertainty in rainfall from climate change. My research examined the use of dendrometers, which measure changes in trunk diameter, and sap flow sensors, which measure how quickly sap moves, as methods to inform growers about tree water status. I also used a weighing lysimeter …

Drought- Conditioning Of Quaking Aspen (Populus Tremuloides Michx.) Seedlings During Nursery Production Modifies Seedling Anatomy And Physiology, Joshua L. Sloan, Owen T. Burney, Jeremiah R. Pinto

Aspen Bibliography

In the western US, quaking aspen (Populus tremuloides Michx.) regenerates primarily by root suckers after disturbances such as low to moderate severity fires. Planting aspen seedlings grown from seed may provide a mechanism to improve restoration success and genetic diversity on severely disturbed sites. However, few studies have examined the use of container-grown aspen seedlings for restoration purposes from both the outplanting and nursery production perspective. Thus, the purpose of this novel study was to examine how alterations in irrigation levels during nursery production across three seed sources would impact seedling performance attributes on harsh, dry outplanting sites. Irrigation …

Sudden Aspen Decline: A Review Of Pattern And Process In A Changing Climate, Jack A. Singer, Rob Turnbull, Mark Foster, Charles Bettigole, Brent R. Frey, Michelle C. Downey, Kristofer R. Covey, Mark S. Ashton

Aspen Bibliography

The American quaking aspen (Populus tremuloides Michx.) and its close relative, the Eurasian quaking aspen (Populus tremula L.), cover a realm that is perhaps the most expansive of all tree species in the world. In North America, sudden aspen decline (SAD) is a growing concern that marks the rapid decline of quaking aspen trees leading to mortality at the stand and landscape scale. Research suggests that drought and water stress are the primary causes of SAD. Predisposing factors (age, structure, and landscape position), as well as associated stressors (i.e., pests and pathogens), have been linked to mortality in affected stands. …

Trends And Controls On Water-Use Efficiency Of An Old-Growth Coniferous Forest In The Pacific Northwest, Yueyang Jiang, Christopher J. Still, Bharat Rastogi, Gerald F. M. Page, Sonia Wharton, Frederick C. Meinzer, Steve Voelker, John B. Kim

Plants, Soils, and Climate Faculty Publications

At the ecosystem scale, water-use efficiency (WUE) is defined broadly as the ratio of carbon assimilated to water evaporated by an ecosystem. WUE is an important aspect of carbon and water cycling and has been used to assess forest ecosystem responses to climate change and rising atmospheric CO₂ concentrations. This study investigates the influence of meteorological and radiation variables on forest WUE by analyzing an 18 year (1998–2015) half-hourly time series of carbon and water fluxes measured with the eddy covariance technique in an old-growth conifer forest in the Pacific Northwest, USA. Three different metrics of WUE exhibit an …

Effect Of Silicon On Wheat Growth And Development In Drought And Salinity Stress, Spencer A. Tibbitts

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Silicon is a major component of most soils, and is found in significant concentration in plant tissue. Plants vary widely in the amount of silicon they take up, with some plants excluding it, and others using transporters to move the silicon from the soil into their roots. Early plant physiology studies were unable to determine conclusively whether silicon was essential to plant growth, but for some plants, most notably rice, it has proved to be important enough to justify fertilizing silicon deficient fields.

Researchers at the USU Crop Physiology Lab tested the effect of silicon on wheat growth and seed …

Concurrent Increases In Wet And Dry Extremes Projected In Texas And Combined Effects On Groundwater, Jin-Ho Yoon, S-Y Simon Wang, Min-Hui Lo, Wen-Ying Wu

Plants, Soils, and Climate Faculty Publications

The US state of Texas has experienced consecutive flooding events since spring 2015 with devastating consequences, yet these happened only a few years after the record drought of 2011. Identifying the effect of climate variability on regional water cycle extremes, such as the predicted occurrence of La Nina in winter 2017–2018 and its association with drought in Texas, remains a challenge. The present analyses use large-ensemble simulations to project the future of water cycle extremes in Texas and assess their connection with the changing El Nino–Southern Oscillation (ENSO) teleconnection under global warming. Large-ensemble simulations indicate that both intense drought and …

Precision Drought Stress In Orchards: Rootstock Evaluation, Trunk Hydration And Canopy Temperature, Lance V. Stott

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Tree fruit crops are of high value, but use a lot of water. Precision irrigation has the potential to save water while simultaneously improving crop quality. The timing and method of precision water stress in various tree fruit crops has been widely studied. However, in order to successfully employ precision irrigation methods in orchards, an accurate measurement of tree water status is required. Currently, stem water potential is the preferred indicator. However, this measurement is tedious and cannot be automated. Because measurements must be taken near solar noon (approximately 1:30 PM MDT in the summer in northern Utah), the number …

Experimental Evidence For Drought Induced Alternative Stable States Of Soil Moisture, David A. Robinson, Scott B. Jones, Inma Lebron, Sabine Reinsch, Maria T. Dominguez, Andrew R. Smith, Davey L. Jones, Miles R. Marshall, Bridget A. Emmett

Plants, Soils, and Climate Faculty Publications

Ecosystems may exhibit alternative stable states (ASS) in response to environmental change. Modelling and observational data broadly support the theory of ASS, however evidence from manipulation experiments supporting this theory is limited. Here, we provide long-term manipulation and observation data supporting the existence of drought induced alternative stable soil moisture states (irreversible soil wetting) in upland Atlantic heath, dominated by Calluna vulgaris (L.) Hull. Manipulated repeated moderate summer drought, and intense natural summer drought both lowered resilience resulting in shifts in soil moisture dynamics. The repeated moderate summer drought decreased winter soil moisture retention by ∼10%. However, intense summer drought, …

Dzuds, Droughts, And Livestock Mortality In Mongolia, Mukund Palat Rao, Nicole K. Davi, Rosanne D. D'Arrigo, Jerry Skees, Baatarbileg Nachin, Caroline Leland, Bradfield Lyon, Shih-Yu (Simon) Wang, Oyunsanaa Byambasuren

Plants, Soils, and Climate Faculty Publications

Recent incidences of mass livestock mortality, known as dzud, have called into question the sustainability of pastoral nomadic herding, the cornerstone of Mongolian culture. A total of 20 million head of livestock perished in the mortality events of 2000–2002, and 2009–2010. To mitigate the effects of such events on the lives of herders, international agencies such as the World Bank are taking increasing interest in developing tailored market-based solutions like index-insurance. Their ultimate success depends on understanding the historical context and underlying causes of mortality. In this paper we examine mortality in 21 Mongolian aimags (provinces) between 1955 and 2013 …

Response Of Stomatal Density And Bound Gas Exchange In Leaves Of Maize To Soil Water Deficit, Wensai Zhao, Yonglin Sun, Roger Kjelgren, Xiping Liu

Plants, Soils, and Climate Faculty Publications

Stomatal behavior in response to drought has been the focus of intensive research, but less attention has been paid to stomatal density. In this study, 5-week-old maize seedlings were exposed to different soil water contents. Stomatal density and size as well as leaf gas exchange were investigated after 2-, 4- and 6-weeks of treatment, which corresponded to the jointing, trumpeting, and filling stages of maize development. Results showed that new stomata were generated continually during leaf growth. Reduced soil water content significantly stimulated stomatal generation, resulting in a significant increase in stomatal density but a decrease in stomatal size and …

Physiological Response Of Kentucky Bluegrass Under Salinity Stress, Lijun Wang

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Salinity is a significant stress for plants world-wide. In agriculture, salts reduce germination, overall growth, yield, and sometimes death in crop plants. Salinity similarly affects turfgrass in our urban landscapes. Kentucky bluegrass (Poa pratensis L.) is the most widely used cool-season grass in the northern part of the United States, including the cool-arid West, but generally is a salt sensitive species. The overall objectives of this study were to study the physiological responses of Kentucky bluegrass to salt stress and to evaluate the genetic similarity among the cultivars used in the research.

Four Kentucky bluegrass entries, two salt-tolerant and …

Prince's Plume In The Landscape, Heidi Kratsch, Graham Hunter

All Current Publications

No abstract provided.

Effect Of Drought, Flooding, And Potassium Stress On The Quantity And Composition Of Root Exudates In Axenic Culture, Amelia Henry

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Root exudates include important chelating compounds and can change the rhizosphere pH by several units. These changes are essential for nutrient uptake and can also alter solubility of soil contaminants and increase plant uptake. Mild root-zone stress may increase exudation and more severe stress can damage membranes and increase root turnover, all of which increase root-zone carbon. Increased carbon from this rhizodeposition can increase microbial activity, which might help degrade contaminants. We studied the effect of three types of stress on root exudation of crested wheatgrass (Agropyron cristatum): low K⁺, drought, and flooding. These stresses were …

Let The Heat And The Drought Work For You, Dennis Hinkamp

All Archived Publications

No abstract provided.

No Miracle Cure For Drought, Dennis Hinkamp

All Archived Publications

No abstract provided.

Factors Affecting Recovery From Defoliation During Drought In Two Aridland Tussock Grasses, Carlos Alberto Busso

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

The importance of several factors in limiting recovery from defoliation was investigated in field-grown plants of Agropyron desertorum and Agropyron spicatum exposed to drought , natural or irrigated conditions. Leaf extension rate, components of leaf area production, number of metabolically active axillary buds and carbohydrate availability were examined on the same plants immediately after defoliation and/or in the following spring from 1984 until 1986.

The diurnal course of leaf growth did not relate to turgor pressure in the expanded portion of leaf laminae. Rather growth was apparently associated with air temperature. Leaf extension rate was lower under drought than under …

Effects Of Drought On The Survival Of Rhizobium Leguminosarum Biovar Trifolii And The Nodulation Of Subterranean Clover In An Acid Soil, Carmen Bueno

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Twenty-nine Rhizobium leguminosarum biovar trifolii strains were tested for acidity tolerance in acidified liquid medium. Only 41% of the strains grew at pH 4.1. One acid-tolerant strain, USDA 2160, and one acid-sensitive strain, 162-X-103 from Nitragin Co., were inoculated on seeds of 'Nungarin', 'Seaton Park' and 'Clare' subclover cultivars. The inoculated and pelleted seeds were sown in potted Cluff soil with pH 5.7. Three desiccation levels were imposed by delaying watering for 0, 15 or 30 days. Four gravimetric soil water contents (6.0, 6.6, 10.5 and 12.5%) were maintained under a greenhouse line-source sprinkler system for 7 weeks. The desiccation …

The Ecology Of Agropyron Inerme On Protected And Heavily Grazed Range Land In Cache Valley, Utah, Wallace R. Hanson

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

During the past decade much attention has been attracted to the great range lands of the West. The inherently low productivity of these arid lands coupled with abnormal drought and constantly heavy use by livestock because of lack of grazing control, have caused these lands to become greatly depleted over most of the West. That the vegetation on most range land in the intermountain states is depleted appreciably is evident to the careful observer. Undoubtedly the vegetation of much of the range has decreased in quantity, but more serious in many cases is the decrease in quality. Valuable forage species …