Microclimate–forage growth linkages across two strongly contrasting precipitation years in a Mediterranean catchment

Given the complex topography of California rangelands, contrasting microclimates affect forage growth at catchment scales. However, documentation of microclimate–forage growth associations is limited, especially in Mediterranean regions experiencing pronounced climate change impacts. To better understand microclimate–forage growth linkages, we monitored forage productivity and root-zone soil temperature and moisture (0–15 and 15–30 cm) in 16 topographic positions in a 10-ha annual grassland catchment in California's Central Coast Range. Data were collected through two strongly contrasting growing seasons, a wet year (2016–17) with 287-mm precipitation and a dry year (2017–18) with 123-mm precipitation. Plant-available soil water storage (0–30 cm) was more than half full for most of the wet year; mean peak standing forage was 2790 kg ha−1 (range: 1597–4570 kg ha−1). The dry year had restricted plant-available water and mean peak standing forage was reduced to 970 kg ha−1 (range: 462–1496 kg ha−1). In the wet year, forage growth appeared energy limited (light and temperature): warmer sites produced more forage across a 3–4°C soil temperature gradient but late season growth was associated with moister sites spanning this energy gradient. In the dry year, the warmest topographic positions produced limited forage across a 10°C soil temperature gradient until late season rainfall in March. Linear models accounting for interactions between soil moisture and temperature explained about half of rapid, springtime forage growth variance. These findings reveal dynamic but clear microclimate–forage growth linkages in complex terrain, and thus, have implications for rangeland drought monitoring and dryland ecosystems modeling under climate change

Low-level volatile organic compounds in active public supply wells as ground-water tracers in the Los Angeles physiographic basin, California, 2000 /

Shipping list no.: 2002-0023-P.Includes bibliographical references (p. 28-29).Mode of access: Internet

Stable isotopes and volatile organic compounds along seven ground-water flow paths in divergent and convergent flow systems, Southern California, 2000 /

"National Water-Quality Assessment Program."Shipping list no.: 2004-0041-P.Includes bibliographical references (p. 78-79).Mode of access: Internet

Grading With Points: The Determination of Report Card Grades by High School Science Teachers

This study examined the grading practices of 91 high school science teachers. Surveys were used to collect data about types of assessments used, the weight given each assessment, and the mechanism used to determine students\u27 report card grades. It was found that few of these teachers used alternative forms of assessment such as performance assessments, journals, or portfolios. While there was little difference among teachers based on experience, gender, or school setting, preference and weights for different assessments varied among science subject taught. These teachers used two types of mechanisms to calculate report card grades: averages and points. Teachers who used point systems for grading purposes were interviewed. The results of this study indicate that reform efforts have had little effect on the grading practices of these teachers. In addition, a large percentage of these teachers use point systems, which act against reform efforts by reinforcing task completion rather than conceptual understanding as the goal for science education

A national survey of methyl tert-butyl ether and other volatile organic compounds in drinking-water sources : results of the randon [i.e. random] survey /

Shipping list no.: 2003-0141-P.At head of title on cover: National Water-Quality Assessment Program, National Synthesis on Volatile Organic Compounds.Includes bibliographical references (p. 47-50).Mode of access: Internet