Life Sciences Commons^™

Effects Of Long-Term Cattle Grazing And Woody Plant Encroachment On Soil Microbial Communities At The Santa Rita Experimental Range, Arizona, Cody Burton, Steven Archer, Rebecca L. Mcculley

Plant and Soil Sciences Presentations

Livestock grazing is considered a key driver of woody plant encroachment in dryland ecosystems worldwide. Woody plant establishment in these systems creates “islands of fertility,” in part by modifying erosional processes such that soil and plant litter are deposited beneath the shrub canopy, creating a nutrient rich soil/litter matrix that supports enhanced soil microbial biomass pools. In this study, we utilized a long-term grazing exclosure (>80 yrs) at the Santa Rita Experimental Range south of Tucson, Arizona and phopsholipid fatty acid analysis to quantify livestock grazing effects on soil microbial communities associated with the complex vegetative mosaic that characterizes …

Idiosyncratic Responses Of Seagrass Phenolic Production Following Sea Urchin Grazing, Latina Steele, John F. Valentine

Biology Faculty Publications

While chemical defenses can determine plant persistence in terrestrial ecosystems and some marine macroalgae, their role in determining seagrass persistence in areas of intense grazing is unknown. As a first step toward determining if concentrations of feeding deterrents in seagrasses increase following herbivore attacks, we conducted 4 experiments using a common macrograzer (sea urchin Lytechinus variegatus) and 2 phylogenetically divergent seagrass species (Thalassia testudinum and Halodule wrightii). Macrograzer impacts on production of phenolic acids and condensed tannins varied somewhat idiosyncratically with season, urchin density, and distance from urchin damage. In general, phenolic concentrations were higher in both turtlegrass and shoalgrass …

Bulletin No. 385 - Comparitive Nutritive Value And Palatability Of Some Introduced And Native Forage Plants For Spring And Summer Grazing, C. Wayne Cook, L. A. Stoddart, Lorin E. Harris

Christopher Cook

From 1952 to 1954 studies were conducted on foothill ranges of central Utah to determine the forage production, palatability, and nutritive value of some of the more important native and introduced species used for spring and summer grazing.

Plants studied were four introduced wheatgrasses (crested, tall, pubescent, and intermediate) , four native grasses (western wheatgrass, beardless wheatgrass, squirreltail grass, and Indian ricegrass), and two introduced annual forbs (Russian-thistle, and smother weed).

Field digestibility trials were conducted to determine the nutrient content by the lignin-ratio technique. In addition, both sheep and cattle preferences were studied on areas where both introduced and …

Monitoring Standing Herbage Of Mid-Grass Prairie On The Fort Pierre National Grassland, South Dakota, Daniel W. Uresk

The Prairie Naturalist

Monitoring vegetation with a modified Robel pole on the Fort Pierre National Grassland was evaluated for combined shallow clay and loamy overflow ecological sites (dominated by warm-season grasses), and for clayey ecological sites (dominated by cool-season grasses). My objectives were to 1) develop a relationship between visual obstruction readings (VOR) and standing herbage, 2) provide guidelines for vegetation monitoring, and 3) evaluate vegetation monitoring during the growing season for clayey ecological sites. The relationship between visual obstruction readings and standing herbage was linear and regression coefficients were highly significant (P < 0.001) for both ecological types. Cluster analyses for shallow clay and loamy overflow ecological sites grouped the VOR and standing herbage (kg•ha-1) into 4 resource categories. Monitoring with 4 transects will provide adequate information to estimate standing herbage within 259 ha (1 section). Three resource categories (VOR + herbage) for clayey ecological sites were defined by cluster analyses. Monitoring with 4 transects was determined to provide reliable estimates of standing herbage. July validation of vegetation with the developed clayey ecological site model will provide reliable monitoring of standing herbage from July through November for this ecological site.

Grasslands And Carbon: Processes And Trends, Rebecca L. Mcculley

Plant and Soil Sciences Presentations

Grasslands, which make up 30% of the U.S. land surface, store significant amounts of carbon belowground in roots and soils. Learn how disturbances such as drought, grazing, fire and tillage can significantly impact the grassland carbon balance.

Dr. Rebecca McCulley of the University of Kentucky, Dept. of Plant & Soil Sciences, talks about grasslands and the way they store and process carbon. Grasslands make up about 30 percent of the North American surface. Grasslands differ from forests in many ways, but from a carbon perspective they store a much greater proportion of the carbon than they take in in any …

A Synoptic Review Of U.S. Rangelands A Technical Document Supporting The Forest Service 2010 Rpa Assessment, Matthew Clark Reeves, John E. Mitchell

USDA Forest Service / UNL Faculty Publications

The Renewable Resources Planning Act of 1974 requires the USDA Forest Service to conduct assessments of resource conditions. This report fulfills that need and focuses on quantifying extent, productivity, and health of U.S. rangelands. Since 1982, the area of U.S. rangelands has decreased at an average rate of 350,000 acres per year owed mostly to conversion to agricultural and residential land uses. Nationally, rangeland productivity has been steady over the last decade, but the Rocky Mountain Assessment Region appears to have moderately increased productivity since 2000. The forage situation is positive and, from a national perspective, U.S. rangelands can probably …