EFFECTS OF FOREST AND GRASS VEGETATION ON FLUVIOKARST HILLSLOPE HYDROLOGY, BOWMAN\u27S BEND, KENTUCKY

Subsurface solutional pathways make limestone terrains sensitive to changes in soil properties that regulate flows to the epikarst. This study examines biogeomorphic factors responsible for changed water movements and erosion in fluviokarst slopes deforested 200 years ago along the Kentucky River, Kentucky. In this project, infiltration and water content data from forest and fescue grass soil profiles were analyzed within a detailed overview of system factors regulating hillslope hydrology. Results show that grass has growth and rooting characteristics that tend to create a larger volume of lateral water movement in upper soil layers than occurs under forests. This sets up the current emergent pattern of erosion in which water perches at grass slope bases and overwhelms pre-existing epikarst drainage. Tree roots are able to cause solution at multiple discrete points of entry into fractures and bedding planes, increasing storage capacity and releasing sediment over time. Grass roots do not enter bedrock, and their rooting depth limits diffuse vertical preferential flow in root channels to above one meter. In the areas dense clay soils, flow under grass is conducted sideways either through the regolith or at the bedrock surface. Rapid flow along rock faces in hillslope benches likely moves fines via subsurface routes from the hillslope shoulders, causing the exposure of flat outcrops under grass. Lower growing season evapotranspiration also promotes higher grass summer flow volumes. Gullying occurs at sensitive points where cutters pass from the uphill grassed area into the forest, or where flow across the bedrock surface crosses grass/forest boundaries oriented vertical to the slope. At these locations, loss of the protective grass root mat, coupled with instigation of tree root preferential flow in saturated soils, causes soil pipes to develop. Fluviokarst land management decisions should be based on site-specific slope, soil depth, and epkarst drainage conditions, since zones sensitive to erosion are formed by spatial and temporal conjunctions of a large number of lithologic, karst, soil, climate, and vegetation factors. This study shows that it is the composite of differing influences created by forest and grass that make forests critical for soil retention in high-energy limestone terrains

Mothers\u27 prosodie features: Strategies to guide young children\u27s understanding of book language

Mothers use prosody to engage children during book reading. Thus, prosody may contribute to children\u27s literacy. The purpose of this study was to describe how twenty-five mothers across children\u27s age groups (6-month olds, 12-month-olds, 18-month-olds, 24-month-olds, and 4-year-olds) used prosody, specifically pitch and stress variations, while reading with their children. Common speech samples from the readings of two different texts (narrative and expository) were analyzed. In addition, the mothers were questioned about their use of expressive language while reading. Patterns from the data showed that the mothers of the 6-month-olds did not vary their speech as often. They used the book reading event to teach basic book reading concepts and to play. The narrative text showed the use of more expressive language. The mothers\u27 intent was to guide children\u27s understanding of the complexities of the story. All the mothers used pitch and stress in conjunction with other book reading strategies to scaffold the texts for their children

Is the Feminist Critique of Reason Rational

Recent criticism of feminist philosophy poses a dilemma. Feminism is taken to be a substantive set of empirical claims and political commitments, whereas philosophy is taken to be a discipline of thought organized by the pursuit of truth, but uncommitted to any particular truth. This paper responds to this dilemma, and defends the project of feminist philosophy

On Judging Epistemic Credibility: Is Social Identity Relevant?

On what basis should we make an epistemic assessment of another’s authority to impart knowledge? Is social identity a legitimate feature to take into account when assessing epistemic reliability? This paper argues that, in some cases, social identity is a relevant feature to take into account in assessing a person’s credibility

Starter Nitrogen Source and Preflood Nitrogen Rate Effects on Rice Grown on Clay Soils

Seedling rice (Oryza sativa L.) grown on clayey-textured soils generally develops slowly as compared to loamy-textured soils. Our research examined the effects of starter-N source and preflood-N rates on canopy closure, total aboveground N uptake, and grain yield of rice grown on clayey-textured soils. Eleven field trials were established in Arkansas and Mississippi including five trials with a hybrid cultivar and six trials using a pure-line cultivar. Starter-N sources included no starter-N (NONE), ammonium sulfate (AMS), diammonium phosphate (DAP), and urea (UREA) applied at 24 kg N ha-1 at the rice 2-leaf stage and five preflood-N rates ranging from 0-224 kg N ha-1 at the 5-leaf stage. Canopy cover was measured weekly on trials conducted in Arkansas for 5 wk after starter-N application. Rice that received no starter-N produced less canopy coverage than rice receiving starter-N as AMS, DAP, and UREA and AMS, DAP, and UREA produced no differences in canopy coverage. Aboveground total-N uptake was affected only by the preflood-N rate for each site-year with maximum N uptake ranging from 139-196 kg N ha-1. The preflood urea-N recovery efficiency for rice receiving no starter-N ranged from 54-78% among trials. For the Arkansas trials, rice that received the three starter-N sources produced 3.4-5.0% greater relative yield compared to rice receiving no starter. Relative yield for the Mississippi trials was not affected by starter-N source. Results show that starter-N can benefit early season growth and grain yield of rice grown on clayey soils but the benefits are not consistent