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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 …

The Kentucky Microbiome Dataset, Rachel L. Washburn, Douglas C. Curl

Research Data--KGS

The Kentucky Microbiome Dataset is a continuously updated geolocated dataset which describes the distribution and diversity of microorganisms across the Commonwealth of Kentucky. Each geolocated point represents a location reported in the peer-reviewed literature where microorganisms were sampled from soil, water, geologic substrates, or clinical settings. Environmental studies include only non-host-associated, non-clinical microorganisms sampled from natural environments. Clinical studies are mapped separately to highlight locations where investigations into host-associated or human health-related microbes have occurred.

For each location, associated metadata include study information, taxonomic classifications, sample type, sampling method, latitude and longitude, sampling date, publication reference, and a direct link …

Remote Sensing-Based Assessment Of Evapotranspiration Patterns In A Unesco World Heritage Site Under Increasing Water Competition, Maria C. Moyano, Monica Garcia, Luis Juana, Laura Recuero, Lucia Tornos, Joshua B. Fisher, Néstor Fernández, Alicia Palacias-Orueta

Biology, Chemistry, and Environmental Sciences Faculty Articles and Research

In water-scarce regions, natural ecosystems and agriculture increasingly compete for limited water resources, intensifying stress during periods of drought. To assess these competing demands, we applied a modified PT-JPL model that incorporates the thermal inertial approach as a substitute for relative humidity (RH) in estimating soil evaporation—a method that significantly outperforms the original PT-JPL formulation in Mediterranean semi-arid irrigated areas. This remote sensing framework enabled us to quantify spatial and temporal variations in water use across both natural and agricultural systems within the UNESCO World Heritage site of Doñana. Our analysis revealed an increasing evapotranspiration (ET) trend in intensified agricultural …

A Novel Approach To Increase Accuracy In Remotely Sensed Evapotranspiration Through Basin Water Balance And Flux Tower Constraints, Kul Khand, Gabriel B. Senay, Mackenzie Friedrichs, Koong Yi, Joshua B. Fisher, Lixin Wang, Kosana Suvočarev, Arman Ahmadi, Housen Chu, Stephen Good, Kanishka Mallick, Justine Missik, Jacob A. Nelson, David E. Reed, Tianxin Wang, Xiangming Xiao

Biology, Chemistry, and Environmental Sciences Faculty Articles and Research

Remote sensing-derived evapotranspiration (RSET) products capture the spatiotemporal variations of evapotranspiration (ET) from field to basin scales with unprecedented details. However, their accuracy varies across RSET estimation methods and diverse hydroclimate regions. While ET modeling efforts to account for biophysical processes and controlling parameters have made good progress in recent years, a parallel approach of integrating in-situ ET with RSET could reduce biases in RSET products. Basin water balance ET (WBET) and flux tower ET are widely applied to evaluate RSET accuracy, yet such ET measurements are rarely used for RSET bias corrections, especially for large area applications. To address …

The Astrobiological Figure Of Humboldt As Pioneer In The Rock Varnish Research, Jose Jordan-Soria

Homage to Alexander von Humboldt: Travels to and from Spain Throughout the Centuries / Homenaje a Alexander von Humboldt: Viajes hacia y desde España de todos los siglos

From Humboldt is particularly interesting -and little know- his description of mineral coatings on rocks 200 years ago, reported in his book Personal Narrative of Travels to the Equinoctial Regions of the New Continent during the years 1799-1804, co-written with Aimé Bonpland, for which is considerate the father of rock coating research. On June 5th 1799 set sail from A Coruña -Spain- to Cumaná -Venezuela- beginning five years of expedition. While they explored the Orinoco River system, in th eriver basin waterfalls, Humboldt observed the presence of dark coating depositions. He ascertained a manganese-rich accretion, reporting similar structures in other …

Modeling The Impact Of Explosive Volcanism On Biogeochemical Cycling At The Peak Of The Late Paleozoic Icehouse, Lily S. Pfeifer, Qingting Wu, Ying Cui, Gerilyn S. Soreghan

Department of Earth and Environmental Studies Faculty Scholarship and Creative Works

The peak of the Late Paleozoic Ice Age (LPIA) coincided with atmospheric carbon dioxide (pCO2) lows, and large-magnitude fluctuations in glacial-interglacial pCO2, but the driver(s) for pCO2 drawdown at this time remain debated. Backed by parameters for the frequency and magnitude of Late Carboniferous volcanism derived from the rock record, we apply an intermediate complexity Earth system model to evaluate the biogeochemical impacts of ash-borne nutrients from frequent (decadal) and explosive silicic volcanism on nutrient cycling ca. 310–300 Ma. Results show that volcanic perturbations result in negligible changes in marine particulate organic carbon export concurrent with sustained increases in pCO2 …

Catching A Fever: A Comparison Of Vachellia Xanthophloea Populations In The Limpopo And Luvuvhu River Floodplains Of The Makuleke Contractual Park, Kianie B. David

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

This study investigates patterns of stand structure regeneration, growth characteristics, and coarse woody debris (CWD) patterns in Vachellia xanthophloea (fever tree) stands within the Makuleke Contractual Park (MCP), a semi-arid savanna system in northern Kruger National Park (KNP), South Africa. Fieldwork was conducted across two stand types: a monospecific fever tree stand in Rietbok Vlei and a mixed-species stand in the Western Nhlangaluwe Floodplain where fever tree is established with Faidherbia albida (ana tree). Data were collected from 20 total 1/4-acre (1,011 m²) circular plots between both stands in 2024 and 2025, including seedling root collar diameter (RCD), …

First Detrital Zircon Provenance Data From Oligocene-Pleistocene Sediment In The Beaufort-Mackenzie Basin, Arctic Ocean, Joseph Martina

Theses and Dissertations

Sediment, runoff, and nutrient input to the Arctic Ocean plays a critical role in both physical and biological processes that impact regional and global systems. The Beaufort-Mackenzie Basin, situated in the Arctic Ocean offshore northwestern Canada, contains more than 14 km of clastic strata and provides a record of erosion and sediment transport from the Cretaceous to present. Pliocene sedimentation rates within the basin jump nearly 2000% relative to underlying units, but the cause of this shift remains unknown. We used cuttings from the N. Issungnak L-86 well, focusing on the Oligocene-lower Miocene Kugmallit and Mackenzie Bay sequences and the …

Using Radium Isotopes To Compare Nutrient Inputs Via Submarine Groundwater Discharge To Offshore Export On The West Florida Shelf, Andrew L. Lindgren

OES Theses and Dissertations

Radium isotopes have been used to trace submarine groundwater discharge (SGD) and associated nutrient and metal inputs into the coastal ocean. They have also been used to estimate rates of diffusive mixing and export fluxes of dissolved constituents offshore. However, use of both approaches in tandem to determine the fate of groundwater inputs after they enter the coastal ocean is still relatively unexplored. Radium isotopes and nutrients were measured in two cross-shelf cruises on the West Florida Shelf in different seasons and in quarterly sampling of offshore wells. Through 226Ra mass balance and 223Ra-derived diffusive mixing rates, inputs of nutrients …

Comparison Of Energy Efficiency And Vegetation In Different Establishment And Management Systems Of Steep Mountainous Grassland In The Aso Area, Japan, K Kabata, C Okamoto, M Shimizu, M Kikuchi

IGC Proceedings (1977-2023)

The Aso area is one of the most important areas for grass­land agriculture in Japan. In this area there exists ca. 44,000 hectares of which ca. 28,700 ha are steep mountainous lands ( a gradient of more than 15 degrees). Additionally, there is much precipitation (ca 2.600 mm/year) in the area. Consequently, there is a problem of grassland destruction due to soil erosion. Therefore, in order to promote the utilization and conser­vation of steep grasslands, the following two experimental grazing were carried out: 1) a two pasture system and 2) a coexistent pasture system with introduced and native grasses. In …

Comparison De La Dynamique De La Vegetation De Deux Ecosystemes Herbagers Mesoxerophiles Apres Deprise Agricole Dans Le Massif Vosgien, S Muller

IGC Proceedings (1977-2023)

Les orientations actuelles de !'agriculture europeenne dans le cadre de la Politique Agricole Commune de la Communaute Economique Europeenne devraient conduire a !'abandon dans les decennies a venir de plusieurs millions d'hectares de terres agricoles en France, entrainant des modifications ecologiques et paysageres considerables. Dans le Massif Vosgien la deprise agricole, consecutive a la regression des industries traditionnelles et a !'elevation du niveau de vie, a provoque !'abandon depuis les annees 1950 de nombreux herbages, autrefois entretenus surtout par des pluri­actifs. Ces milieux evoluent alors vers des friches herbacees seboisant plus ou moins rapidement de maniere spontanee.

Massif Vosgien constitue …

Le Role Des Plantes Herbageres Dans La Limitation Des Pertes Des Principaux Elements Nutritifs Par Le Drainage, S Kopec

IGC Proceedings (1977-2023)

Depuis longtemps on connait !'action anti-erosive des plan­tes herbageres qui empechent d'une fa< ;on tres efficace l'affais­sement des particules de sol, en particulier sur des surfaces en pente. Dans ces derniers temps on parle de plus en plus souvent du role des herbages dans la limitation du drainage des elements nutritifs du sol et de nombreuses recherches menees a cet effet dans plusieurs pays le confirment (Jones, 1972; Gachon et Tri­boi, 1967; Kopec, 1985). Dans cette etude on a presente les resultats des recherches lysimetriques Sur la quantite des principaux elements nutritifs draines par les eaux s'evacuant des terrains agricoles couverts d'herbages et d'autres cultures.

Degradation Models And Their Use In Determining The Condition Of Southern African Grasslands, O.J H. Bosch, K Kellner, S.H E. Scheepers

IGC Proceedings (1977-2023)

An understanding of the processes of change is an important prerequisite for the development of techniques for the monitor­ing of condition and trend, and to interpret the ecological sig­nificance of determined condition classes. The approach to develop and use degradation models for determining range condition is illustrated in this paper by means of basic ecological data from the relatively high rainfall zone in the climatic climax grasslands (Mentis and Huntley, 1982) of southern Africa.

An Experiment And Study On A Air-Seeding Astragalus Adsurgens For Soil Conservation On The Loess Plateau Of China, Yimin Liang, Daiqiong Li, Xinhai Cong

IGC Proceedings (1977-2023)

The irrational land utilization has resulted in destruction of original vegetation and serious soil erosion on the Loess Pla­teau in China. At present, 1600 million ton of sediment is disch­arged into the Yell ow River per year. In order to explore effec­tive avenues to speed reestablishing vegetation for controlling soil erosion, we made an experiment in seeding forage and shrubs by airplane for four years, from 1976 to 1979, in semi­arid region on the Loess Plateau. We selected suitable plant species for aerial seeding on semiarid region, determined fit aerial seeding time and seeding rate through manual broadcast and air-seeding. …

Role Potentiel Des Legumineuses Annuelles A Ressemis En France, P Masson, G Gintzburger

IGC Proceedings (1977-2023)

L'interet pour les legumineuses annuelles a ressemis est recent en France malgre !'importance de la zone mediterra­neenne et atlantique dont ces plantes sont originaires. Le trefle souterrain (Trifolium subterraneum) et les luzernes annuelles (Medicago sp.) apparaissent respectivement dans notre littera­ture specialisee a la suite de travaux d'amelioration pastorate en Corse (Etienne, 1977) et des travaux de plusieurs labora­toires de l'Institut National de la Recherche Agronomique a Montpellier (Gintzburger et Prosperi, 1987). Apres 4 ans d'experimentation dans diverses situations des Pyrenees Orientates dans le sud de la France en climat mediter­raneen (pluviometrie moyenne annuelle de 575 mm a …

Agroforestry In The Southeastern United States, H A. Pearson, C E. Lewis

IGC Proceedings (1977-2023)

Agroforestry has been practiced for many years in the tropics by intermixing forages under palms, fruit trees, or hardwoods. Interest has increased in temperate zones for combining trees, pastures, crops, and livestock. Agroforestry in the United States is generally limited to the combining of pines, tame pastures, and cattle. Our purpose is to summarize results of research and developments in the southeastern United States on cool-and warm-season forages under planted pines and pine regeneration in tame pasture.

The Effects Of Heavy Metals Applied In Digested Sewage Sludge To Grassland, A Desira Buttigieg, D A. Klessa, D A. Hall

IGC Proceedings (1977-2023)

The application of potentially toxic elements in sewage sludge to grassland has implications to environmental pol­lution and the health of grazing rumiµants. In Scotland, mod­erately acid grassland receives most of the sewage sludge applied to agricultural land and there is therefore a risk of heavy metal mobilisation and uptake by herbage. In addition, soil ingestion (Fleming, 1986) and intake of herbage contami­nated with sludge adhering to leaf surfaces may present an important means by which potentially toxic elements are absorbed by ruminants. In this paper, two aspects of sewage sludge use on grassland are studied, namely : 1. Factors affecting …

Increasing Flora Diversity In Grassland Swards, R J. Haggar, D Jones

IGC Proceedings (1977-2023)

Europe's farmers are being encouraged to take land out of agriculture in order to reduce surplus cereal production. There is therefore, increasing scope for creating new species-rich swards, although guidelines for this purpose are lacking. Several reasons are advanced for encouraging species diver­sity and conservation, including recreational, ethical, education and resource utilisation. As leisure time increases, so public interest in conservation matters increases. Scientifically, there is a need to preserve genetic diversity and to understand the com­plex plant and animal relationship leading to a rich and varied community. This paper describes two experiments aimed at achieving a . highly diverse …

Grass Plan Density For Adequate Conservation Reserve Program Stands, D W. Meyer, D Rugroden

IGC Proceedings (1977-2023)

The Conservation Reserve Program (CRP), a federal program with the objective to reduce surplus feed grain pro­duction in the United States by idling marginal cropland, has already idled nearly 12 million hectares with a target of 32 mil­lion hectares. Idled land must be seeded to perennial grasses to help prevent soil erosion. The required grass seeding has caused the cost of grass seed to increase several fold ; therefore, estab­lishment cost could be reduced considerably if seeding rates could be reduced from the present recommended 215 to 323 seeds/m2 (Dodds, 1981). Recommended seeding rates were developed from research on establishment …

Multiple Of The Intermountain Region, Forest Service, United States Department Of Agriculture, J S. Tixier, A H. Winward

IGC Proceedings (1977-2023)

Initial custodians of the National Forests of the United States were primarily concerned about protecting what were perceived as deteriorating timber stands and watersheds. Con­siderable progress was made in correcting these problems in the first half of this Century. As the population of the United States grew, more people became interested in management of all resources on these public lands. Forest Officers gradually became stewards managing a broad array of lands and resources for which there were often conflicting interests and uses. A primary use of National Forests in the Western United States has been livestock grazing. Here, animals are …

Phosphatic Settling Pond Clays As Potential Forage Legume Seed Production Site, D D. Baltensperger, G M. Prine, D S. Wofford

IGC Proceedings (1977-2023)

Forage legume species perform a vital role in the agriculture of the state of Florida (Baltensperger et al., 1985a, 1985b, and 1987; Taylord et al., 1985). Cool-season cultivars adapted to this climate must also perform well in the Pacific Northwest or California since these are the primary areas of commercial seed production (Baltensperger et al., 1987). Commercial seed for the wa:m��s_eason species is typically produced in Florida. A pri­mary hm1tmg factor for seed production in Florida is the low water-holding-capacity of the sandy soils which necessitates frequent irrigation, subsequently reducing seed quality. Potential seed production areas include reclaimed phosphate minelands …

Influence Of Reduced Intensity Of Grassland Management On Herbage Yield, Forage Quality, Sod Density And Botanical Composition, P Dahmen, W Kuhbauch, U Thome

IGC Proceedings (1977-2023)

In the Federal State of Northrhine Westfalia, a number of programs have been initiated to reduce intensity of land use with respect to unwanted environmental effects presumably coming from conventional agricultural systems. On grassland most of the programs require delayed first cuttings for hay and silage, reduced fertilization and/or less grazing pressure on pastures. Field experiments were established in order to evalu­ate consequences of these programs for practical farming and grassland ecology. Treatments include conventional grassland management systems with intensive fertilization and utilization as well as intermediate and low intensity systems.

Limits For Cattle Slurry Application On Permanent Grassland, B Stratmann, W Kuhbauch

IGC Proceedings (1977-2023)

Several experiments indicate little risk of groundwater pol­lution with nitrate under permanent grass (DVWK 1985), but only few studies deal with surface water contamination due to grassland fertilization, especially slurry spreading. The purpose of this work was to determine the effect of cattle slurry in comparison to mineral nitrogen fertilization on surface run-off and interflow quality under different inclinated permanent grassland (18 % and 4.5 % resp.).

Effects Of Incorporation Of Organic Material And/Or Limestone On Grasses Grown On Acid Coal Refuse, B D. Gardner, She-Kong Chong, F J. Olsen

IGC Proceedings (1977-2023)

Disposal of coal preparation wastes is a serious environmen­tal problem. Waste materials whose particle size is less than 2 mm are classified as slurry. About 67 000 hectares in the U.S.A. are affected by surface disposal of coal mining wastes. These materials tend to be acid, draughty and possess high surface temperatures thus retarding natural succession on affected sites. Regulations require that slurry impoundments be covered with 120 cm of non-toxic material and revegetated. The cost of such treatment can exceed $ 24,000 per hectare (Kosowski, 1973). Brundage (1974) and Sukthumrong (1975) concluded that alternate, less expensive methods could be …

On The Resource Of Chinese White Clover (Trifolium Repens L.), Zhu Bangchang

IGC Proceedings (1977-2023)

China is one of the countries in the world rich in legume. According to the research of Dr Sun-xingdong, the late herbalist, among the Chinese local genera Trifolium, there are white clover (Trifolium repens L. ), and so on; all of them number about more than ten species. White clover has a specially important place in the herbage resource in every province of South China. Chinese white clover is distributed mainly over the range of 22°-51° north latitude, 80°-130° east longitude. The range of optimal temperature for white clover is l9°-24°C, but under -15°C (minimum temperature) in winter, it …

Nutritional Quality Of Subterranean Clover Cultivars In West Central Spain, B Garcia-Criado, A Garcia-Ciudad, M Rico-Rodriguez, L Garcia-Criado

IGC Proceedings (1977-2023)

The nutritional quality of 61 subterranean clover (Trifolium subterraneum L.) cultivars was studied, during 1982, in the province of Salamanca (semiarid zone of west central Spain). Plant samples were collected at the late-bloom stage and were analyzed for protein, carbohydrates and digestibility. The levels of all these constituents fluctuated within acceptable ranges. Higher relative variability was observed in respect of hemicellulose, protein and lignin, while the digestibility values presented lower relative variability. The latter ranged from 71.1 to 76.1 % with a mean of 73.3%, while protein values ranged from 11.1 to 19.4% with a mean of 14.0%. Chemical …

Influence Of Diverse Harvest Schedules On Evaluation Of Birdsfoot Trefoil Cultivar Compared To Alfalfa, C C. Sheaffer, G C. Marten

IGC Proceedings (1977-2023)

Birdsfoot trefoil (Lotus corniculatus; BFf) cultivars, including the recently released 'Noreen', have not been adequately evaluated for their response to a diversity of harvest managements. Our objective was to determine the effect of three harvest schedules on forage yield, forage quality, and stand persistence of BFf cultivars and an adapted cultivar of alfalfa (Medicago sativa). 'Empire', 'Viking', 'Maitland', 'Carroll', 'Leo', and Noreen BFf and 'Ramsey' alfalfa were established in monocultures and in binary timothy mixtures (Phleum pratense). Stockpile (two harvests), recommended hay (three harvests), and simulated pasture (four harvests) schedules were applied for 3 years. Noreen …

Evaluation Of Miyakogusa (Lotus Corniculatus L. Var. Japonicus Regel): Population Distributed In Japan, S Saiga, K Suginobu, Shinji Suzuki

IGC Proceedings (1977-2023)

Twenty-one Miyakogusa populations collected from all over Japan were evaluated with 3 birdsfoot trefoil cul ti vars at four different locations between 1982 and 1984. Generally, Miyakogusa showed poor spring vigor, more prostrate type, lower plant height, fewer stems, earlier flowering, less winter hardiness and poor fall vigor. These populations were classified into 5 groups using Principal Component Analysis (PCA) and Cluster Analysis. As the results of PCA plant type, maturity and winter hardiness are mainly extracted for the first, second and third principal component, respectively. Populations belonging to group V and IV, having high scores of the first component …

Identifying Winter Hardy Alfalfa (Medicago Sativa) For Northwestern Canada, J S. Mckenzie, G E. Mclean

IGC Proceedings (1977-2023)

Winter kill is one of the most serious problems affecting alfalfa production in northwestern Canada. A rapid and accurate means of assessing winter hardiness is invaluable in developing new cultivars for this region. This program was designed to define some plant and environmental factors responsible for winter injury and to develop tests to identify plants with high yield potential and resistance to severe winter stress in northwestern Canada. The program has determined that the cold hardiness of alfalfa can change from year to year depending upon the plant and/or environmental conditions during the growing season. Three factors have been identified …

Fringed Sagebrush, Ming Chang Wang

IGC Proceedings (1977-2023)

Fringed sagebruch (Artemisia frigida will) is one of the common plants in inner mongolia plateau. It was recognized as an excellent perennial herbaceous plants accunting for a large proportion in wild vegetation. Fringed sagebruch belongs to composites, Semi-frutex, tomentellate in whole plant, tap root may be 100 cm deep in the soil. Fringed sagebrush distributed to the north of the Yellow River in China, Fareast and Caucasus in USSR, Mongolia and Canada. Fringed sagebruch is an excellent forage for horses, cattle, sheep, goats and Camels. The animals will get gain if fringed sagebruch is fed.