Journal of Natural Resources and Life Sciences Education最新文献

It is difficult to demonstrate the soil water retention relationship and related concepts because the specialized equipment required for performing these measurements is unavailable in most classrooms. This article outlines a low-cost, easily visualized method by which these concepts can be demonstrated in most any classroom. Columns (62.5 cm tall) were constructed using 25, 2.5 cm tall sections of 7.62-cm (3-inch) i.d. polyvinyl chloride pipe, which were connected using transparent tape. Three different soil materials were packed to specified bulk densities in the columns, and saturated with water. These vertical columns were then allowed to drain into a simulated water table 2.5 cm above the bottom of the soil volume until drainage ceased. After drainage, columns were sectioned to determine water content distribution with depth along the column. It was assumed that matric potential was inversely related to height above the water table. Therefore, water content measurements and assumed potentials for each section provided data for a water retention curve with minimum potential of approximately –60 cm. During drainage, measurements of soil matric potential were taken at regular intervals using tensiometers installed within the column, validating assumptions about matric potential. Among soil materials tested, those with narrow particle-size distributions, ∼100% sand, gave the widest distribution of water contents in the observed matric potential ranges. This method, with proper explanation and execution, may be a valuable learning tool by which visual, auditory, and kinesthetic learners may be better able to understand the concepts pertaining to soil–water retention relationships.

To assist student understanding of heat transfer through woody stems, we developed an instructional package that included an Excel-based, one-dimensional simulation model and a companion instructional worksheet. Guiding undergraduate botany students to applying principles of thermodynamics to plants in nature is fraught with two main obstacles: (1) students have a limited knowledge of heat transfer fundamentals, and (2) the highly complex and cognitively demanding analysis of the plant thermal environment. To provide the necessary background, reduce the complexity, and allow students to process information in a step-wise fashion, the computer simulation permits students to vary heat transfer properties for the bark and xylem, along with lateral stem dimensions, to visualize the resulting diurnal transient radial temperature distribution throughout the stem. Additionally, the maximum cambial temperature excursion could be visualized, along with the phase difference between the cambial temperature and the outer bark temperature at any time. A paper-based instructional worksheet guides students through a series of questions and leads them through the learning process. They acquire basic concepts of heat transfer and apply their observations to ecophysiological conditions such as heat stress on saplings, the insulative value of bark, and the impact of fire on the cambium. Anecdotal evidence indicated that the computer simulation proved to be a valuable tool for students because it reinforced woody stem structure and placed it into context of a tree's physiological response to temperature.

Mastering the concept of photosynthesis is of critical importance to learning plant physiology and its applications, but seems to be one of the more challenging concepts in biology. This teaching challenge is no doubt compounded by the complexity by which plants alter photosynthesis in different environments. Here we suggest the use of chlorophyll fluorometers in the undergraduate plant physiology classroom as one means to enhance conceptual learning of photosynthesis and its acclimation to changing environments. We also provide an overview of current research in photosynthetic acclimation to changing conditions, review the methodological considerations of making good F_v/F_m measurements with small inexpensive fluorometers, and suggest an open-inquiry activity for teaching concepts of photosynthesis and photo-acclimation with fluorometers in an undergraduate plant physiology course.

Spatial and temporal variability of riparian areas, as well as potential impacts from climate change, are concepts that land and water managers and stakeholders need to understand to effectively manage and protect riparian areas. Rapid population growth in the southwestern United States, and multiple-use designation of most riparian areas, makes understanding these concepts even more important. To assist in this endeavor, the Watershed/Riparian and Climate Science Extension programs at the University of Arizona developed two experiential learning exercises with repeat photographs of riparian areas. Experiential learning is the process of learning from direct experiences; repeat photography, a tool for long-term monitoring, provides visual details of landscapes across large temporal scales. The goal of the exercises was to increase the participant's knowledge on certain topics through active participation, communication, problem-based learning, critical thinking, and empowerment. The first exercise examined precipitation, stream flow, and potential climate change impacts on riparian areas. The second exercise investigated how riparian areas change around the state of Arizona and through time while trying to understand the factors that cause these changes. The participants’ evaluations indicate that their knowledge level increased after conducting the exercises. In addition, the exercises are a more pleasant way of learning than the traditional teaching methods. These exercises were specific to the southwestern United States but could easily be adapted by extension professionals in other regions of the United States as well as for university courses. The plethora of repeat photographs is an unexploited resource that should be utilized for educational purposes.

Phosphorus (P) is the limiting nutrient controlling productivity in most inland freshwater systems. Several materials have been proposed for use to remove excess P from wastewater treatment, including volcanic lapilli and ash (tephra). There is limited data in using tephra as a P filter. There were two objectives of this study: 1) to determine the physical feasibility of tephra as a filter making sure the infiltration rate remains high enough to use under prolonged saturation, and 2) to test the suitability of volcanic tephra as a medium for removing P from an artificial solution on two different volcanic tephra materials: Okato and Papakai tephra. The experiment used a synthetic P influent solution (20.5 mg P/L) and a solution residence time in the columns of approximately 3 hours. By the end of the experiment infiltration in both tephras was adequate for use in wastewater treatment systems. The Okato tephra absorbed nearly 8 mg P/g tephra with 97% of the total amount of P added to the column over a 54 day period. The Papakai tephra absorbed only 4 mg P/g with a 52% of the total P added to the column.

A field-based, soil methods, and instrumentation course was developed to expose graduate students to numerous strategies for measuring soil parameters. Given the northern latitude of North Dakota State University and the rapid onset of winter, this course met once per week for the first 8 weeks of the fall semester and centered on the field as a classroom, allowing the students to learn through hands-on participation. The major focus of the course was providing a real-life example where the scientific method was used to answer a testable hypothesis. Students developed testable hypotheses, designed an experiment, determined sampling protocol and sample analysis, conducted statistical analysis, and wrote results in a peer-reviewed format. The research question for this course was, “What is the concentration of total mercury (Hg) in roadside soils of North Dakota?” The results from the student project indicated that total soil Hg concentration increased with increasing distance from the roadside shoulder and that total soil Hg concentration was not statistically different between high-traffic and low-traffic areas. Field-based courses and student-driven research projects are excellent ways to introduce research methods to graduate students. Student learning was enhanced during the experiential learning process by allowing the students to follow the scientific method starting from the formulation of ideas (research question and testable hypotheses) to the preparation of a manuscript.