Earth Sciences Commons^™

Spring Forage Stash Module To Prevent Forage Crisis On Uruguayan Livestock Systems: An Evaluation Based On Model Simulations, M. Pereira Machín, F. Dieguez Cameroni

IGC Proceedings (1977-2023)

In Uruguay, rangeland cattle production systems support national economy by beef exportation chain and economic inputs to the country. Soil hydric stress episodes results to forage crisis on grassland-based production systems, having high impact on its trajectory and leaving sequels at several farm levels mainly on rearing cattle systems in drought sensitive regions of the country. In that context, the proposal is to create a spring forage stash module, with a simple management rules as a mechanism to build stability to farms and to buffering drought impact. The concept is to differ spring forage (season with low variation coefficient on …

Species Richness Increased Yield Stability In Intensively Managed Grasslands Subjected To Experimental Drought, J. A. Finn, M. Suter, E. Haughey, D. Hofer, A. Lüscher

IGC Proceedings (1977-2023)

Climate change is expected to cause an increase in the frequency and intensity of drought events. Over two years we investigated the effects of experimentally imposed drought on intensively managed grassland communities (5 m x 6 m plots) of varying richness (1, 2 and 4 species), and comprising four species (Lolium perenne L., Cichorium intybus L., Trifolium repens L., Trifolium pratense L.). In each year a summer drought period of nine weeks with complete exclusion of precipitation was simulated, inducing severe drought stress at Reckenholz (Zürich, Switzerland), and extreme drought stress at Wexford (Ireland). Mean yield and plot-to-plot variance …

Elevated Co2 And Extreme Climatic Events Modify Nitrogen Content And Ruminal Protein Digestion Of Temperate Grassland, V. Niderkorn, C. Picon-Cochard

IGC Proceedings (1977-2023)

This study was aimed at analyzing changes in nitrogen (N) content and in vitro protein rumen digestion of an upland grassland exposed to climate changes in controlled conditions. Monoliths of grassland were inserted in 12 macrocosms in which climatic conditions for the 2050s were simulated (i.e., +2.3°C and 33 mm less precipitation compared to the current climatic conditions). Six of them were subjected to ambient CO₂ (390 ppm) while the other six were subjected to elevated CO₂ (520 ppm). After four months, an extreme climatic event (ECE) consisting of four weeks of reducted precipitation (-50%) followed by two …

Climate Change Threats To Semi-Arid Transhumance Grazing Systems: Proposals For Adaptation In Cabo Verde, J. F. Castro, S. Tavares, M. Castro

IGC Proceedings (1977-2023)

Global warming has changed the rainfall regime in the Sahelian region, endangering and widespread poverty and chronic famines in Cape Verde, where rural communities' well-being and food security depend on rainy agriculture. Local responses to rainfall new patterns and scarcity have been livestock reduction with significant revenue losses. Together with dry mist occurrences, these environmental constraints demand to define priority actions to adapt and mitigate climate change's direct impacts. According to fifty household inquiries, this work explains the transhumant grazing practices on a semi-arid plateau in Tarrafal (Santiago, Cabo Verde), prospecting adaptation alternatives for sustainability. We related grazing patterns and …

Interactive Effects Of Drought And Fire On Co-Existing Woody And Herbaceous Communities In A Temperate Mesic Grassland, R. Keen, J. Nippert, E. Tooley, K. O’Keefe, S. Bachle, M. Sandwick

IGC Proceedings (1977-2023)

Increased drought and woody encroachment are likely to have substantial and interactive effects on grassland carbon and water cycling in the future. However, we currently lack necessary information to accurately predict grassland responses to drought-by-fire interactions in areas experiencing woody encroachment. A more thorough understanding of these interactive effects on grass-shrub physiology would improve the effectiveness of demographic vegetation models and refine predictions of future changes in grassland ecosystem function. To this end, we constructed passive rainout shelters over mature Cornus drummondii shrubs and co-existing grasses in two fire treatments (1-year and 4-year burn frequency) at the Konza Prairie Biological …

Droughtscape, Winter 2022, National Drought Mitigation Center

DroughtScape: Quarterly Newsletter of the National Drought Mitigation Center (2007–2023)

DroughtScape, Winter 2022

Poor Acclimation To Experimental Field Drought In Subalpine Forest Tree Seedlings, Alex Goke, Patrick H. Martin

Biological Sciences: Faculty Scholarship

The ability of tree species to acclimate and tolerate projected increases in drought frequency and intensity has fundamental implications for future forest dynamics with climate change. Inquiries to date on the drought tolerance capacities of tree species, however, have focused almost exclusively on mature trees with scant in situ work on seedlings, despite the central role that regeneration dynamics play in forest responses to changing conditions. We subjected naturally established seedlings of co-dominant subalpine conifer species (Abies lasiocarpa and Picea engelmannii) in the southern Rocky Mountains to 2 years of in situ summer precipitation exclusion, simulating summer drought …

Forage Quality And The Environment, C. E. Lascano, A. Schmidt, R. Barahona

IGC Proceedings (1977-2023)

The influence of environmental factors on forage quality of temperate and tropical grasses has been reviewed by several authors, who summarized how light, temperature, drought and soil nutrients influence chemical composition, and digestibility of forages grown in contrasting areas of the world. The effects of season of the year on forage growth, grazing behavior and animal performance have also been the subject of numerous papers and reviews. However, there are few recent reviews that summarize how changes in climatic and edaphic factors influence forage quality of legumes with variable levels of condensed tannins (CT), which are important secondary compounds in …

Floodplain Forests Vegetation Dynamics Driven By Water Deficits Across Scales, Nga Thanh Nguyen

LSU Doctoral Dissertations

Restoration of floodplain ecosystems relies on identifying the most crucial hydrologic process which has been altered by human and climate. Flooding is a well-known dominant hydrologic process for floodplain ecosystems, but surprisingly little is known about drought's role in structuring ecosystems. In addition, several issues remained uncertain, such as the nature of drought within floodplains and the sensitivity of floodplain species-specific growth to climate. These gaps of understanding have in common in missing observations of mechanistic pathways of vegetation response to water deficits at multiple scales in time and space.Generally, this research contributed to floodplain management by expanding our understanding …

The Effect Of Water Deficits During Flowering And Seed Production On Cultivars Of Subterranean Clover And Annual Medic, E. C. Wolfe, W. J. Collins, R. C. Rossiter, W. R. Stern

IGC Proceedings (1977-2023)

In improved pastures in inland southern Australia, the persistence and growth of annual pasture legumes depends in part on their ability to produce and conserve abundant seed for regeneration and production. For near-maximum seed production in spring, adequate soil water is needed for at least 70 days in subterranean clover (Trifolium subterraneum) and medic (Medicago) species. Water deficits during spring are a common occurrence, and they appear to be increasing in frequency. The effect of relatively short periods of water deficit during reproductive development has received some attention but the findings conflict. The present experiment was …

Effect Of Drought Stress On Fibre Digestibility Of Corn For Silage, G. Ferreira, C. L. Teets, A. M. Kingori, J. O. Ondiek

IGC Proceedings (1977-2023)

Limited information exists about the impact of drought stress on corn silage digestibility. The objective of this study was to determine the effect of irrigation on in situ NDF digestibility of corn tissues grown under controlled conditions in a greenhouse. Five commercial corn hybrids were planted in pots and grown in a greenhouse. Pots were subjected to an abundant or restricted irrigation regime. Leaf blades and stem internodes were collected from the upper and bottom portion of each hybrid. Tissue samples were incubated in the rumen of 3 rumen-cannulated cows for 0, 3, 6, 12, 24, 48, 96, and 240 …

Strategies For Assessing Grassland Degradation With Biogeochemical Models, S. Rolinski, S. B. Wirth, C. Müller, B. Tietjen

IGC Proceedings (1977-2023)

Marginal grasslands provide the basis for livestock rearing and rural livelihoods globally, but are subject to permanent degradation from mismanagement and climate change. Global biogeochemical models are so far not able to represent degradation tipping points in marginal grasslands because plant growth is dependent only on bio-climatic conditions and nutrient availability. Due to their central role for sustaining livelihoods, this lack of representation in such models needs to be addressed. We present an idea on processes and interactions to be considered and on the actual implementation of necessary changes. The model for which we exemplarily develop implementation strategies, LPJmL, accounts …

Hydraulic Responses Of Shrubs And Grasses To Fire Frequency And Drought In A Tallgrass Prairie Experiencing Bush Encroachment, K. O’Keefe, R. Keen, E. Tooley, S. Bachle, J. B. Nippert, K. Mcculloh

IGC Proceedings (1977-2023)

The increase in abundance and density of woody plants in herbaceous ecosystems (i.e. bush encroachment) is occurring globally and is driven by reduced fire frequency, climate change, and the utilization of deeper, more reliable soil water by woody plants. Thus, a comprehensive understanding of the physiological processes through which woody and herbaceous plants use water will provide greater insight into the mechanisms of bush encroachment, as well as the trajectory of encroachment in a changing climate. Our objective was to assess how experimental changes in water availability and fire frequency impact belowground water-use traits in Cornus drummondii, the primary …

Climate Variability In The Woodbush Granite Grasslands Of South Africa: Effects On Grassland Diversity, M. Muller, F. Siebert, A. Linstädter, D. I. Thompson, S. J. Siebert

IGC Proceedings (1977-2023)

South African old-growth grasslands are hyper-diverse ecosystems which evolved under naturally occurring rainfall variability. It is predicted that future precipitation patterns will become more variable, which could lead to increased frequencies of extreme and prolonged drought events. This study aimed to investigate the effects of climate variability on plant diversity of the fragmented pristine, mistbelt grasslands of the Woodbush Granite Grasslands (WGG) at Haenertsburg, South Africa. It has been reported that species composition has changed substantially in this area, as disturbance-tolerant species enter these systems or existing competitor species become more dominant. A Temporal Beta-diversity Index (TBI) was used to …

Droughtscape, Fall 2021, National Drought Mitigation Center

DroughtScape: Quarterly Newsletter of the National Drought Mitigation Center (2007–2023)

DroughtScape, Fall 2021

Adaptation Of Forage Species To Drought, D. J. Barker, J. R. Caradus

IGC Proceedings (1977-2023)

Variability in rainfall is the single greatest cause of variation in forage production for a given site. Current climate scenarios predict future annual rainfall to decrease at some geographic regions. The intensity of future rainfall is also predicted to increase at other regions, with the expectation of greater variability in soil moisture. The adaptation of forage species to drought is an issue that is likely to remain with us into the future.

Precise definitions are critical to water relations work, and imprecise use of terms has complicated comparisons of some studies on plant response to drought. Drought is a purely …

Defoliation And Water Deficit: Their Influence On Pasture Growth And Water Use Of White Clover, F. H. Santiñaque

IGC Proceedings (1977-2023)

With the objective of understanding the physiological basis of defoliation and water use relationships of white clover (Trifolium repens L.) pastures during water deficits, an experiment in controlled conditions was carried out. Outdoors nine liters pots were filled with a loam-clay soil with a water content at field capacity (FC), of 35%(w/w), at a bulk density of 1.1 g/cm³. Pre-germinated and inoculated clover seeds were transplanted, and the number of plants was adjusted to permit the development of full plant cover. The level of P in the soil did not limit plant establishment or growth. The …

The Grassbank Concept: Potential Applications In China?, Wenjun Li, Lynn Huntsinger, Sally K. Fairfax

IGC Proceedings (1977-2023)

No abstract provided.

Droughtscape, Summer 2021, National Drought Mitigation Center

DroughtScape: Quarterly Newsletter of the National Drought Mitigation Center (2007–2023)

DroughtScape, Summer 2021

Amino Acid And Protein Incorporation In Water‐Stressed Perennial Ryegrass, W. J. Jung, B. R. Lee, L. S. Li, Y. L. Jin, T. H. Kim

IGC Proceedings (1977-2023)

No abstract provided.

The North Central Texas Urban Heat Island Magnitude And Its Relation To Severe And Extreme Drought, Linnea Clarke Standard

Earth & Environmental Sciences Theses - Archive

This study focuses on how summer droughts affect the urban heat island (UHI) in Dallas-Fort Worth (DFW). The nocturnal UHI has been computed by comparing downtown temperature observations to rural temperature measurements under the condition that wind speed is less than 2 m/s, a cloudless sky, and no precipitation. To understand the combined effects of long-term climate change and UHI, trends of temperature anomalies from 1902 - 2019 for Waco and 1900 – 2019 DFW from NOAA COOP were determined relative to a baseline of 1951-1980. The differing trends of these temperature anomalies have been influenced by the UHI (which …

Extreme Event Reconstructions For The Upper Fraser River Basin, British Columbia, Canada, Inga K. Homfeld

UNLV Theses, Dissertations, Professional Papers, and Capstones

Spring freshets and summer droughts have recently worsened in the Fraser River Basin, British Columbia, Canada, with significant impacts to the keystone Pacific salmon populations, the food and economic sovereignty of over eighty First Nations, and the western Canadian economy. These extreme events present a potential risk since, unlike many large and less hydroclimatically-complex and/or empounded watersheds, the Fraser River Basin is susceptible to a combination of unregulated spring freshet and summer drought events even within the same year. A major limitation for understanding past and future extreme event risk in the Fraser River Basin is that observational streamflow datasets …

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, …

Droughtscape, Spring 2021, National Drought Mitigation Center

DroughtScape: Quarterly Newsletter of the National Drought Mitigation Center (2007–2023)

DroughtScape, Spring 2021

Identification, Evaluation And Molecular Characterization Of Stylosanthes Seabrana--A Potential And Nutritious Range Legume Having Wider Applicability In India, A. Chandra, R. K. Bhatt, A. B. Majumdar, S. Kumar, D. Nagaich, K. Kumar

IGC Proceedings (1977-2023)

No abstract provided.

Carbon Isotope Discrimination, Selection Response, And Forage Production Of Tall Fescue In Contrasting Environments, R. C. Johnson, Andrew A. Hopkins, M. A. Evans

IGC Proceedings (1977-2023)

No abstract provided.

Metabolic Response Of Lolium Perenne To Drought Stress, Heike Hahn, J. Kopka, Oliver Fiehn, B. Scott

IGC Proceedings (1977-2023)

No abstract provided.

A Record Of Vapour Pressure Deficit Preserved In Wood And Soil Across Biomes, Adrian Broz, Gregory J. Retallack, Toby M. Maxwell, Lucas C.R. Silva

Biology Faculty Publications and Presentations

The drying power of air, or vapour pressure deficit (VPD), is an important measurement of potential plant stress and productivity. Estimates of VPD values of the past are integral for understanding the link between rising modern atmospheric carbon dioxide (pCO₂) and global water balance. A geological record of VPD is needed for paleoclimate studies of past greenhouse spikes which attempt to constrain future climate, but at present there are few quantitative atmospheric moisture proxies that can be applied to fossil material. Here we show that VPD leaves a permanent record in the slope (S) of least-squares …

Ranchers’ Use Of Drought Contingency Plans In Protective Action Decision Making, Tonya Haigh, Michael Hayes, Jolene Smyth, Linda Stalker Prokopy, Charles A. Francis, Mark Burbach

National Drought Mitigation Center: Faculty Publications

Drought contingency planning is an increasingly common tool in the ranchers’ climate adaptation toolboxes, but its effect on drought response has not yet been evaluated. We use cognitive models of protective action decision making and planning to explore the effects of having a drought plan on the use of drought early warning information and drought response (and timing). Results of a cross-sectional, probability-based survey of livestock producers affected by a 2016 flash-drought are used to describe the characteristics of operations with drought plans and provide evidence of whether having a plan predicts drought information use and response. While larger operations …

Droughtscape, Winter 2021, National Drought Mitigation Center

DroughtScape: Quarterly Newsletter of the National Drought Mitigation Center (2007–2023)

DroughtScape, Winter 2021