Phenology and microclimate

The Fairy Chasm Scientific Area encompasses twenty acres at the Lake Michigan end of a series of ravines that begin approximately 1 1/4 miles west of the shore of Lake Michigan in Ozaukee County. These ravines vary from sixty to one hundred feet in depth and have some slopes greater than 45°. The protection of the slopes, the cool air draining down them, and the cool winds coming off the lake, create a microclimate suitable for many northern species of plants. This study examined the effects of different microclimates on the phenology of several plant species. A second objective involved testing the applicability of the duration-summation temperature method of heat accumulation (Lindsey and Newman 1956) to an area of diverse topography

Submergent macrophytes in Theresa Marsh

Marshes form the interface between upland and aquatic systems and, like most transitional zones, provide habitat diversity which may support a great variety of life. Marshes may act as valves or sinks to regulate the flow of mineral nutrients from terrestrial systems (especially from agricultural or urban systems) to aquatic zones. Freshwater marshes and wetlands are ranked with coastal estuaries as highly productive areas and play an important role in converting the sun\u27s energy to organic matter

Ruminant Methanogenic Activity in the United States Beef Cattle Industry

In the U.S., gastrointestinal fermentation from cattle is estimated to account for approximately 25% of total anthropogenic related methane (CH4) emissions. In addition, 2-8% of gross energy consumed by cattle is lost in the form of CH4, representing an energetic cost to the animal. Thereby, in order to decrease greenhouse gas emissions (GHG) and improve the efficiency of cattle production additional research on gastrointestinal CH4 emissions from cattle is needed. In ruminants carbohydrate (CHO) catabolism and nitrogen (N) utilization have a tremendous impact on ruminal methanogenesis. However, the impact of purified carbohydrates in the presence of a variety of N sources on rates of CH4 and VFA production remains unknown. In order to determine these rates for use in predictive models of the ruminal fermentation, we formulated a fractional rate equation to fit the rate of CH4 production and measured the concentration of CH4 and VFA and using purified CHO with a variety of N sources in two in vitro mixed ruminal microorganism fermentation studies. In both studies, a CHO treatment × incubation time (IT) effect was observed for both VFA and CH4 (P < 0.01). There was also an N × IT interaction for CH4 production at 24 h in Study 2, where nitrogen free and NH3 treatments produced greater concentrations of CH4 than treatments with amino acids (P < 0.01). A nonlinear equation for the conversion of carbohydrates to CH4 was able to fit starch treatments in Study 1 and glucose treatments in Study 2. Overall, this study demonstrated different fermentation patterns among all CHO and N sources and was the first step in determining rates for in vitro CH4 production. Although cattle contribute with high amounts of anthropologic GHG, they are not the only methanogenic producing food source in the U.S. Rice and wild ruminants (e.g. bison, elk, and deer) are also methanogenic producing food sources. The objective of this final study was to compare the efficiency of beef and milk production to pre-settlement wild ruminants and rice production on a kilogram of CH4 emitted to kilogram human-edible protein production basis. Bison had the highest ratio of 13.93 kg CH4: Protein, followed by elk (12.50) deer (6.66) and beef (2.47). Overall, wild ruminants emitted 296 to 564 percent more CH4 per kilogram of human-edible protein produced than current beef cattle production systems. Rice yielded the second lowest CH4 to human-edible protein ratio (0.83), followed by dairy cattle milk production (0.50). We believe, this analysis provides insight on the efficiency of methanogenic food sources that may aid in the development of regulatory guidelines of CH4 production

Investigating the Impact of Unlimited Sucrose During Adolescence on Flex Maze Performance in Rats

As depression continues to impact many people, there are important considerations to be taken in how depression impacts people\u27s learning and motivations. The objective of this study is to examine the effects of unlimited sucrose consumption during adolescence, which can mimic symptoms of depression, on spatial memory and motivation in rats. The flex maze is used in the present study to assess these behaviors. Before initial training on the flex maze, 6 male rats were separated into two groups: an experimental group with unlimited access to 5% sucrose (and water) for approximately 3 weeks and a control group with free access to two bottles of plain water. Rats were first trained to complete the maze and during testing trials the time to complete the maze and the number of errors were recorded. Previous research has concluded that male rats fed a high-sucrose diet exhibited a delay in their ability to make decisions (Wong et al., 2017). Thus, we hypothesize that rats given unlimited access to sucrose water during adolescence would move slower in the flex maze due to the delay in making cognitive decisions because of depressive symptoms compared to control rats

Evaluating the Shelf Life and Sensory Properties of Beef Steaks from Cattle Raised on Different Grass Feeding Systems in the Western United States

Consumer interest in grass-fed beef has been steadily rising due to consumer perception of its potential benefits. This interest has led to a growing demand for niche market beef, particularly in the western United States. Therefore, the objective of this study was to assess the impact of feeding systems on the change in microbial counts, color, and lipid oxidation of steaks during retail display, and on their sensory attributes. The systems included: conventional grain-fed (CON), 20 months-grass-fed (20GF), 25-months-grass-fed (25GF) and 20-months-grass-fed + 45-day-grain-fed (45GR). The results indicate that steaks in the 20GF group displayed a darker lean and fat color, and a lower oxidation state than those in the 25GF group. However, the feeding system did not have an impact on pH or objective tenderness of beef steaks. In addition, consumers and trained panelist did not detect a difference in taste or flavor between the 20GF or 25GF steaks but expressed a preference for the CON and 45GR steaks, indicating that an increased grazing period may improve the color and oxidative stability of beef, while a short supplementation with grain may improve eating quality

Substrate age and tree islands influence carbon and nitrogen dynamics across a retrogressive semiarid chronosequence

The long-term dynamics of carbon (C) and nitrogen (N) in semiarid ecosystems remain poorly understood. We measured pools and fluxes of surface soil C and N, as well as other soil properties, under tree canopies and in intercanopy spaces at four sites that form a volcanic substrate age gradient in semiarid piñon-juniper woodlands of northern Arizona, United States. Clay content and soil water-holding capacity increased consistently with substrate age, but both soil organic C and N increased only up to the 750,000 year site and then declined at the oldest (3,000,000 year) site. Measures of soil C and N flux displayed a similar pattern to total C and N pools. Pools and fluxes of C and N among the three canopy types became more homogeneous with substrate age up to the 750,000 year site, but disparity between tree and intercanopy microsites widened again at the oldest site. The δ15N of both tree leaves and surface soils became progressively more enriched across the substrate age gradient, consistent with a N cycle increasingly dominated by isotope fractionating losses. Our results point to consistencies in patterns of ecosystem development between semiarid and more humid ecosystems and suggest that pedogenic development may be an important factor controlling the spatial distribution of soil resources in semiarid ecosystems. These data should help both unify and broaden current theory of terrestrial ecosystem development

Mycorrhizal occurrence in willows in a northern freshwater wetland

Willows growing in a north central Michigan wetland were found to be ectomycorrhizal throughout the 1978 growing season on each of two sites (one water-saturated, one relatively drier). Each site was dominated by a mix of sedges ( Carex spp.) and willows ( Salix spp.). On both sites, phosphorus was added at two levels (20 or 200 kg P ha −1 ) to simulate potential inputs from the disposal of secondarily-treated municipal wastewater. The intensity of willow root infection was determined by scoring root tips on a 0 to 4 scale based on mantle-, intercellular hyphae-, and root epidermal cell characteristics.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/43474/1/11104_2005_Article_BF02184550.pd

Carbon pools and fluxes along an environmental gradient in northern Arizona

Carbon pools and fluxes were quantified along an environmental gradient in northern Arizona. Data are presented on vegetation, litter, and soil C pools and soil CO2 fluxes from ecosystems ranging from shrub-steppe through woodlands to coniferous forest and the ecotones in between. Carbon pool sizes and fluxes in these semiarid ecosystems vary with temperature and precipitation and are strongly influenced by canopy cover. Ecosystem respiration is approximately 50 percent greater in the more mesic, forest environment than in the dry shrub-steppe environment. Soil respiration rates within a site vary seasonally with temperature but appear to be constrained by low soil moisture during dry summer months, when approximately 75% of total annual soil respiration occurs. Total annual amount of CO2 respired across all sites is positively correlated with annual precipitation and negatively correlated with temperature. Results suggest that changes in the amount and periodicity of precipitation will have a greater effect on C pools and fluxes than will changes in temperature :in the semiarid Southwestern United States