Treesearch

Over the course of 1681 hours between May 5 and September 30, 2006, air temperatures measured at the 1.5-m height at seven sites in and near the city of Baltimore, MD were used to empirically model Δ Tˆ R-p , the difference in air temperature between a site in downtown Baltimore and the six other sites. Variables in the prediction equation included difference between the downtown reference and each of the other sites in upwind tree cover and impervious cover as obtained from 10-m resolution geographic information system (GIS) data. Other predictor variables included an index of atmospheric...

In this Natural Inquirer Freshwater edition, you will learn many new things about Earth’s freshwater. In "Green Means Clean," you will learn how scientists and managers are protecting U.S. drinking water supplies using better land management practices. Water pollution that cannot be traced to a particular source is the subject of "What’s the Nonpoint?" You will learn how the amount and type of living, or once-living, matter in a waterway changes over time in "Caribbean Cruise." Have you ever wondered whether chemicals flowing into urban waterways are dangerous? You will learn whether those...

In 2002, a wildfire burned over an ongoing sediment flux study in the steep, chaparral-covered foothills of the San Gabriel Mountains of southern California. The study area had previously burned in 1960. Southern California experiences a Mediterranean climate with cool wet winters and hot dry summers. Average annual rainfall for the study area is 714 mm (80-year record) with an average two-year 30-minute peak intensity of 29 mm hr-1. Hillslope erosion was measured in 30 cm collector traps. These traps were serviced multiple times per year to distinguish wet season from dry season erosion....

Models that quantify the probability of stump sprouting P(s) and sprout characteristics for predominant tree species in the southern Appalachian Mountains, USA are lacking. In this study, 375 plots (0.01 ha) were installed across five stands in eastern Tennessee and western North Carolina. Trees C3.8 cm diameter at 1.37 m above groundline (dbh) were tagged, and dbh and species recorded. Stands were regenerated using a two-aged silvicultural system (residual basal area (BA) \6.3 m2 ha-1 ). One growing season post-harvest, we recorded (1) sprouting (yes/no), (2) the number of sprouts per...

The mountain pine beetle-killed lodgepole pine (Pinus contorta) wood treated with iron (III) nitrate solution was used for the preparation of Fe-cored carbon nanomaterials (Fe-CNs) under various carbonization temperatures. The carbonization yield of Fe-treated sample (5% as Fe) was always 1–3% higher (after ash compensation) than that of the non-treated samples heated at the same condition.The lowest carbonization temperature required to produce Fe-CNs was 700° C. The carbon shell was composed of 30–40 well-aligned layers of graphitic carbon nanostructure.The iron captured by graphitic...

Previous research revealed that stress wave nondestructive testing techniques could be used to evaluate the tensile and flexural properties of wood-based composite materials. Regression models were developed that related stress wave transmission characteristics (velocity and attenuation) to modulus of elasticity and strength. The developed regression models accounted for over 94% of these materials’ observed elastic properties and for over 90% of their observed strength. The original models were developed using wood-based particle composite specimens. The study presented in this paper...

The use of a variety of stress wave transmission techniques for the in-service condition assessment of deteriorated wood is well documented. This paper summarizes results from an extensive study designed to examine the relationship between ultrasound transmission times and the deterioration of exposed wood. Two hundred seventy (270) southern pine lumber specimens were evaluated nondestructively using a through transmission ultrasound technique after field exposure for periods of up to fifty seven (57) months. Ultrasound transmission times increased with exposure time. Several statistical...