Earth Sciences Commons^™

Climatic Influences During Flowering On Seed Dormancy And Seed Formation Of Stylosanthes Hamata Cv. Verano, P J. Argel, L R. Humphreys

IGC Proceedings (1977-2023)

Effects of variation in temperature, soil moisture supply, and illuminance on seed dormancy and seed formation of Srylosan­thes hamata cv. Verano were studied. Plants were grown in the open in successive seasons, in controlled-temperature cabinets, and in the greenhouse where shading and watering treatments were varied after the onset of flowering. Hardseededness was strongly developed and was positively related to temperature during seed formation. After seed matura­tion, seed moisture content was the main factor governing hardseededness, and this quality was negatively associated with temperature during seed formation. High levels of hardseededness developed in all seeds when seed moisture content was …

Resource Allocation For Animal-Grassland Systems, G W. Thomas

IGC Proceedings (1977-2023)

The production of animal products from grasslands is dependent upon an adequate resource base-particularly the availabil­ity ofland, water, and energy. In addition, range and pasture production systems must be designed to adjust to climatic varia­tions and to minimize adverse environmental impacts. Several new developments will have a significant impact on the future allocation of resources for animal agriculture: (1) in­creased competition for land and water, which is leading to transfers from agricultural to nonagricultural uses; (2) increasing costs and decreasing availability of "cultural energy" (particularly fossil fuels); (3) more pressure to divert grains and feed con­centrates from animals to direct …

Bridging The Gap: Evaluating Gnss-Derived Total Water Storage As A Groundwater Monitoring Tool In The Colorado River Basin, Michelle Lee Barton

Graduate Student Theses, Dissertations, & Professional Papers

Groundwater resources in the Colorado River Basin are critically stressed yet remain under-monitored and under-regulated, creating urgent need for reliable, continuous observations at multiple spatial scales. This study evaluates the performance of the University of Montana Global Navigation Satellite Systems (GNSS) terrestrial water storage dataset as a tool for bridging groundwater monitoring gaps across the Upper and Lower Colorado River Basins between 2006 and 2024. We compare GNSS-derived total water storage and groundwater storage estimates against NASA’s Gravity Recovery and Climate Experiment (GRACE) satellite observations and in-situ groundwater well measurements at regional and sub-regional scales. We employ a Bayesian autoregressive …

Stream Temperature Responses To Summer Urban Rain Events Along The Savannah River, Joseph E. Wermter, Vivian L. Turner, Max K. Appelbaum, James M. Shepherd, Jacob Z. Lott

Journal of South Carolina Water Resources

The hydrological urban heat island (HUHI) is a recent facet of the urban heat island (UHI), describing thermal enhancement of bodies of water in response to urbanization. Although the forefront of this work has been studied for large Metropolitan areas, this effect on developing cities is currently unknown. To locally measure and quantify HUHI effects in a developing city, we utilized Multi-Radar Multi Sensor (MRMS) radar-derived rainfall data to estimate rainfall in the Augusta Metropolitan Area (AMA) and the Savannah Metropolitan Area (SMA), two developing communities adjacent to the Savannah River. We analyzed mean temperature trends of two stream gauges …

Unraveling Snow And Rain Contributions To Streamflow Through A Methodological Investigation On Cold And Warm Season End-Members, Rachel Grena

Boise State University Theses and Dissertations

Water supply and demand are encountering unique challenges in the western United States as climate change impacts the availability of water resources. Much of the west relies on high mountain snowpack to maintain consistent streamflow throughout the dry, warm season months. Temperatures often rise above freezing in the cold season, diminishing the snowpack size, and altering the timing of snowmelt. As droughts become more frequent, water managers are increasingly concerned about the risk of reduced summer streamflow. To understand changing hydrologic patterns, this study utilizes phase changes in precipitation, specifically the distinction between cold and warm season precipitation, and their …

Measuring The Impact On Landscape And Sediment Transport Of Climate And Anthropogenic Influence In The Mississippi River Since 2000 Bce, Bailey Wycoff

LSU Master's Theses

Understanding river dynamics is crucial to being able to interpret the geological history preserved in sediment deposited on continental margins, deltas, and alluvial plains. Sediment buffering can be a key control on the sediment flux to the ocean and involves sediment storage and recycling in flood plains. The efficiency of the transport varies depending on climatic and more recently anthropogenic influences. Sediment moving through meandering streams may be temporarily deposited in a point bar on the convex side of a meandering river. Meanders are sometimes cut off, creating an oxbow lake and filled in. The area of study, False River, …

Seeking Structure In Complex Systems: From Feature Analysis To Space-Time Causal Discovery With Earth Science Applications, Jeffrey J. Nichol

Computer Science ETDs

Complex systems are difficult to study because of their many interacting parts, emergent phenomena, and feedback loops. These systems underpin all life on Earth. We need improved tools for seeking an understanding of them. This body of research presents my investigations into data-driven methods for understanding complex systems, including my invention of a novel causal discovery meta-algorithm for space-time gridded data. I demonstrated machine learning feature importance and causal discovery capabilities for comparing simulated and observed climate data. I developed a new benchmark for modeling space-time dynamics of locally driven phenomena and examined a prominent causal discovery algorithm. Finding that …

Comparing California Annual Grassland Management Beliefs With Evidence From The Field, R J. King

IGC Proceedings (1977-2023)

Annual grasslands in California's Mediterranean climate are generally believed to have been dominated by perennial grasses prior to European settlement (Burchan, 1957 ; Heady, 1977). Numerous exotic annual species have been introduced, natura­lized, and now dominate grassland communities. Overgrazing by domestic livestock and replacement by aggressive introduced annuals are regarded as the primary factors respon­sible for the displacement of perennial species. Range scientists and managers have established a doctrine that annual grasslands are now fundamentally different from perennial grasslands. The range management profession's current goal for proper grazing of annual grassland is simply to maintain adequate litter on the soil …

Increasing Annual Rainfall As Recorded At Five Weather Stations In The Cedar River Watershed And Adjacent, Eastern Iowa, Lee S. Potter

The Compass: Earth Science Journal of Sigma Gamma Epsilon

Monthly and annual rainfall totals were examined from five weather stations in and near the Cedar River watershed in eastern Iowa. The basin has headwaters in southern Minnesota and trends northwest to southeast across the eastern part of the state. Graphical presentation highlights noisy signals within these, with annual values showing increase of about 4 to 7 inches over the most recent 100 years. This information is presented without reference to correlation with broader climate signals to inform residents and policy makers of the increasing trend. Monthly totals show consistent increase April and June, with lesser increases in May, July, …

Prediction Of Live-Weight Gain Of Cattle Grazing Pastures On Brigalow Soil, M Hirata, C K. Mcdonald, R M. Jones

IGC Proceedings (1977-2023)

A model for predicting the live-weight gain-(LWD) of cattle from climatic conditions and pasture and cattle attributes was developed. The model was calibrated and validated against the data from a long-term grazing experiment on brigalow soil, sown with green panic pastures. When validated, the model tended to overestimate LWG as the proportion of green panic (Panicum maximum var. trichoglume) in the pasture decreased, because the model was calibrated, without considering species composition, to data from years when green panic was dominant. This study emphasises the limitations of empirical models of grazing systems. The study also implies that there …

Rain-On-Snow Event Climatology And Hydrological Impacts In The Connecticut River Watershed, Samuel Davidson

Masters Theses & Specialist Projects

Rain-on-snow events, characterized by rain falling on existing snowpack, have the potential to bring about significant hydrological and environmental impacts including snowmelt, flooding, landslides, and other natural hazards. Despite prior evidence suggesting the Connecticut River Watershed has endured socioeconomic and environmental setbacks due to rain-on-snow events in the past, limited prior research has been performed on the role of rain-onsnow events within the region’s hydroclimatology. Gaining a deeper understanding of the occurrence and impacts of such events would provide valuable insights for risk and water resource managers. The purpose of this research was to create a climatology of rain-on-snow events …

Changes In Efficiency And Magnitude Of Recharge Due To Climate Change For Headwater Catchments In The Mountain West, Harrison Mcgillen

Graduate Student Theses, Dissertations, & Professional Papers

Changes to groundwater recharge and stream flow were simulated from downscaled CMIP6 global climate models in a headwater catchment of the Blackfoot River, MT. A calibrated, 3-D, coupled surface and groundwater GSFLOW model, forced with minimum and maximum temperature, and precipitation from a downscaled CMIP6 simulation was used to quantify groundwater recharge and stream flow. The model was calibrated against measured groundwater head and stream flow using observed temperature and precipitation boundary conditions. The calibrated model was then forced with downscaled temperature and precipitation from the CANESM5 model for the SSP245, 370 and 585 scenarios, as well as a manual …

Multi-Centennial Spatial Coherency Among Atlantic Tropical Cyclones From Simulated And Reconstructed Storm Records, Richard M. Sullivan, Elizabeth Wallace, Sylvia Dee, Gabiel A. Vecchi, Wenchang Yang, Kerry Emanuel

OES Faculty Publications

Proxy-based reconstructions of long-term Atlantic tropical cyclone (TC) variability reveal low-frequency oscillations in regional TC landfalls over the Common Era. However, the limited spatial coverage and increased uncertainty of the proxy records complicates assessments of this feature. Here we present a new multi-ensemble set of synthetic TCs downscaled from the Last Millennium Reanalysis project, which is based on sea surface temperatures that more accurately reflect past conditions. Throughout ensemble members, there are coherent multi-centennial shifts in landfalls with persistent intervals of increased (decreased) occurrence along the eastern US concurrent with inverse activity in the southwest Caribbean and Gulf of Mexico, …

Flowering And Seed Production Of Centrosema Spp. In Relation To Day Length And Temperature, R.J M. Gonzalez, R J. Clements, L R. Humphreys

IGC Proceedings (1977-2023)

The effcc1s of variation in daylength and temperature on the flowering processes leading to seed production were studied in genotypes of 5 Centrosema spp. Short days (11 h) enhanced flowering in accessions of C. virginatum from low latitude but flowering of lines from high latitude was more prolific in 16-h days. A quantitative long-short day response was evident in 2 intermediate latitude accessions. The critical photoperiod for flowering·varied: C. virginianum cross 31 flowered in 13.5 h or less, C. pubescens, C. pascuorum and C. macrocarpum in 12 h or less, and C. schiediam Oowcred only in a 10.5 …

Herbage Seed Production In Norway, Ragnar Hillestad

IGC Proceedings (1977-2023)

Seed of all important species of perennial grasses and clover for northern areas can be produced in Norway, with good quality, at about 60°N. Norway has built up its own plant breeding with seed production and is self-supporting in seed of the most important species for use in agriculture. The seed yield per area unit of grass species decreases from south lo north, but there are differences among cullivars depending on where the breeding work has been carried out. The short growing·season makes it difficult for some species to establish a good stand so the plants can flower and give …

Efficient Nitrogen Fertilizer Strategies For Tropical Beef And Dairy Production Using Summer Rainfall And Soil Analysis, M A. Gilbert, N M. Clarkson

IGC Proceedings (1977-2023)

Nitrogen (N) deficiency is a major limitation to growth of pastures in tropical and subtropical regions. In the tropics and subtropics of north-eastern Australia, grass yield is curvilinearly related (R2=0.75) to summer rainfall and the rate of N fertiliser. Data from a range of grazing experiments also indicate that beef and dairy production (kg/ ha) are related to N fertiliser rate in a curvilinear manner; production is near optimum at N rates of 250-300 kg N/ha/year, when summer rainfall is >1000 mm. Given the importance of summer rainfall and N fertiliser, climatic analysis can enhance the usefulness of N fertiliser …

Pasture Production Of Annual, Hybrid And Perennial Ryegrasses In Cool And Warm Temperature Climates, D E. Hume, M J. Hickey

IGC Proceedings (1977-2023)

Pasture production and persistence of 8 ryegrass species-cultivars were evaluated under 2 grazing frequencies (infrequent and frequent) in a cool temperate climate (Southland) and a warm temperate climate (Manawatu) in New Zealand. All pastures were sown with white clover (Trifolirim repe11s) and rotationally grazed with sheep for 3 years. The 8 ryegrass lines were divided botanically into cultivars of annual ryegrass (Lo/ium muftljlorum), hybrid ryegrass (L. boucl1eanu111) (most of the parentage derived from L. multiflorum) and perennial ryegrass (L. pere,me). Infrequent grazing resulted in higher yields and particularly higher ryegrass yields, but lower ryegrass tiller numbers at the cool site. …

Climate, Land Use And Plant Life Form Distribution In A Semi-Arid Savanna, Christina Skarpe

IGC Proceedings (1977-2023)

Number of plant species, total vegetation cover and the abundance of different life forms are compared over a rainfall gradient between savanna woodland and semi-desert. The effects of different land use intensities are superimposed on the differences in rainfall regimes. The outcome is discussed in the light of present global change scenarios,

Vegetation Response To Climate: A 35 Year Study At Bibury, Gloucestershire, A J. Willis, R Hunt, J P. Grime, S R. Band, N Dunnett

IGC Proceedings (1977-2023)

Important information on the climate-responsiveness of plant species has been gleaned from an unlikely source. The annually recorded control {unsprayed) plots from a 35-year field e, experiment assessing the effects of spraying herbicide and a plant growth regulator onto the vegetation of roadside verges near Bibury, Gloucestershire, have provided an opportunity to examine the detailed effects of year-to year variations in climate on the yields of different ·species and functional types within the vegetation. The results confirm the usefulness of plant functional types and genome size as predictors of plant community response to climatic change.

The Integrated Screening Programme: Patterns Of Ecological Specialization In British Species, K Thompson, J P. Grime, R Colasanti

IGC Proceedings (1977-2023)

The Integrated Screening Programme (ISP), a major part of the UCPB research programme during the period 1987-1994, applies standardised procedures for the ecological, physiological and biochemical characterisation of plant species, populations or cultivars. The objectives are: (1) to establish the range of variation in selected plant attributes; (2) to recognise recurring patterns of ecological and evolutionary specialisation; (3) to devise a functional classification of plants relevant to the analysis of communities and ecosystems and the management of vegetation .. To date, the programme has been confined largely to the herbaceous species from central northern Britain. Later, and in particular as …

Interaction Of Climate Management As Controls On Species Composition, S H. Hillier, F Sutton, J P. Grime, R Colasanti

IGC Proceedings (1977-2023)

A new technique for the manipulation of temperature near the soil surface without the aid of cloches or screens has been developed at UCPE. This system is being used to manipulate the length of the growing season in an experiment in which the critical interaction between growth and the timing of two important meadow management activities - cutting and grazing - is being investigated. The technique has also been used to expose synthesised meadow communities to an artificially induced mild winter. Temperature manipulations of this kind offer a new approach to understanding the role which climate plays as a mechanism …

Simulating The Impact Of Global Warming On Regional Pasture Production Environment, P J. Vickery, M J. Hill, E P. Furnival

IGC Proceedings (1977-2023)

Global warming scenarios predict increases in temperatures, evaporation and summer rainfall in the northern two-thirds of Australia. Pasture production models can be combined with spatial climate data in a geographic information system to predict net primary production from pastures. We used a pasture-sheep production model for a phalaris-white clover pasture together with interpolated climatic data to predict the outcome of increases in temperature, evaporation and summer rainfall for net primary production (NPP) from pastures in northern NSW. NPP was predicted to rise in winter due to elevated temperatures, to decline slightly In spring due to increased evaporation, and to change …

Changing The Climate Of A Limestone Dale, S M. Buckland, J P. Grime, J R. Tippets, A Jackson, K Thompson, J G. Hodgson, P C. Thorpe, C W. Macgillivray

IGC Proceedings (1977-2023)

The Unit of Comparative Plant Ecology based at Sheffield University is manipulating the weather artificially at a field site near Buxton, Derbyshire. This experiment is enabling us to study the way in which certain plants, both in the existing vegetation and among potential invaders, may behave in the future. As well as future climate scenarios, a range of land-use conditions are recreated in the experiment. Seeds of species with different geographical distributions have been sown in and their fate is being closely followed. The experiment began in 1990 and will run until at least 1997, by which time it should …

Climate Change And Grasslands: A Life-Zone And Biota Perspective, Steven Archer

IGC Proceedings (1977-2023)

Grasslands experiencing climatic and atmospheric change may be altered with respect to: (1) geographic extent and location of local/ regional boundaries; (2) productivity, organic matter dynamics and nutrient cycling; and (3) the relative abundance of constituent life forms (woody v. herbaceous), growth forms (tall vs. shorl-statured grasses), and/or photosynthetic physiologies (C3 v. C4). Classification models based on vegetation-climate correlations predict an increase in the global acreage of grassland and savanna at the expense of boceal forest and dry tropical forest. However, extrapolation of these relationships to climates with atmospheric CO2 concentrations without present-day analogues is suspect. Dynamic models of plant …

Investigating Arctic Ocean Freshwater Content And Circulation In A Changing Climate, Emma Louise Hoffman

Theses and Dissertations

The Arctic Ocean is unique among the world’s oceans, characterized by its cold temperatures, salinity-driven vertical structure, and shallow shelf seas. It has warmed intensely since the 1980s at rates exceeding the global average. This Arctic Amplification drives variability in sea ice and salinity, affecting local circulation and exchange with other basins, leading to global changes in oceanic and atmospheric circulation and the biosphere. This thesis explores changing dynamics in the Arctic Ocean, in particular connecting modeled changes in liquid freshwater content (FWC) and its pathways with major ocean circulation patterns, atmospheric drivers, and large-scale climatic changes.

This research combines …

A Search For Persistent Perennial Legumes For Temperate Australia, M J. Hill, C Mulcahy, G Rapp

IGC Proceedings (1977-2023)

Problems with persistence of white clover (Trifolium repens L.) in extensive pastures of the high rainfall zone in eastern Australia necessitate the use of a wider range of perennial legumes. A range of species have been evaluated in nurseries and in regional on-farm trials on the northern Tablelands of New South Wales. Caucasian clover and I.oms spp. have proven most successful so far. Caucasian clover has been more productive than white clover at 2 sites in spring 1991 and autumn 1992, Hexaploid Caucasian clover has been subjected to the first of 3 cycles of recurrent selection for seedling vigour. …

Effect Of Manipulative Management Options On A Degraded Pasture Within The Astrebla Spp. Grazing Lands Of Western Queensland, J J. Bushell, J A. Reynolds, D C. Cowan, D G. Phelps, J A. Milson

IGC Proceedings (1977-2023)

A reduction in Aslrebla spp., and an increase in less palatable and less desirable forbs (Malvastmm americanum Psoralea cinerea), was identified as a problem in some paddocks of the Astrebla grazing lands of central western Queensland's clay soils. To determine possible rehabilitation for these pastures and assist the recovery of Astrebla spp,, a 2-year experiment was conducted near Muttaburra, Queensland (460 mm average annual rainfall), Six main treatments (nil, tine ripping, herbicide, slashing, fire, and a pioneering grass) were combined in a 6x2x2 split piot structure with grazed/not grazed and with additional Astrebla lappacea seed sown/not sown. Interim …

Onset Of Antarctic Glaciation At The Eocene-Oligocene Transition In The Weddell Sea And Its Impact On Ocean Circulation, Victoria Hojnacki

Theses, Dissertations and Culminating Projects

The Eocene – Oligocene Transition (EOT) (34 Ma) represents a greenhouse to icehouse climate transition that is marked by the appearance of permanent ice sheets in Antarctica. Studying this period of climate change allows us to understand how different Earth systems reacted under changing atmospheric CO₂ conditions. Though the timing of the development of the East Antarctic Ice Sheet is well supported, the development of the West Antarctic Ice Sheet is still up for debate. Ocean Drilling Program Site 696 is the only paleoarchive of the EOT in the Weddell Sea region and offers an opportunity to better constrain the …

Analysis Of Drought-Flood Abrupt Alternation Events And Their Impacts In Kenya, Betty Makena

School of Natural Resources: Dissertations, Theses, and Student Research

Drought-Flood Abrupt Alternation (DFAA) is a compound disaster event that refers to the abrupt shift of extreme drought events to extreme floods resulting in exacerbated impacts on already vulnerable communities and hindering their coping abilities. This study aimed to analyze drought-flood abrupt alternation events and their impacts in Kenya. The first chapter aimed to understand historical drought events in the Greater Horn of Africa and their impacts, while drawing comparisons with the recent 2020-2022 drought period, referred to as the ‘triple dip La Niña’. Datasets used in this study include the Climate Hazards Group InfraRed Precipitation with Station (CHIRPS), Normalized …

Will It Rain? Managing El Nino Risks With The Australian Rainman Computer Package, N M. Clarkson, J F. Clewett, D T. Owens, D G. Abrecht

IGC Proceedings (1977-2023)

The AUSTRALIAN RAINMAN computer package helps the management of climatic risks associated with the ENSO (El Niño/ Southern Oscillation) phenomenon in the southern Pacific region. The package uses historical rainfall and Southern Oscillation Index (SOI) records to provide a suite of analyses including user-defined seasonal forecasts. Examples are given of ENSO effects on precipitation in Australia and some other countries including Canada. The SOI has a multiplier effect on rain-dependent processes such as plant growth and stream flow, and its use provides valuable support for many agricultural and pastoral decisions. AUSTRALIAN RAINMAN is commercially available in Australia.