Treesearch

We investigated depth of water uptake of trees on shale-derived soils in order to assess the importance of roots over a meter deep as a driver of water use in a central Pennsylvania catchment. This information is not only needed to improve basic understanding of water use in these forests but also to improve descriptions of root function at depth in hydrologic process models. The study took place at the Susquehanna Shale Hills Critical Zone Observatory in central Pennsylvania. We asked two main questions: (i) Do trees in a mixed-hardwood, humid temperate forest in a central Pennsylvania...

Additives that alter the rheology of lignocellulosic biomass suspensions were tested under conditions of variable pH, temperature, and solid concentration. The effects of certain ions, biomass type, after the addition of rheological modifier were also examined. Torque and vane rheometry were used to measure the yield stress of samples. It was found that the effectiveness of rheological modifiers depends on pH over a range of 1.5 to 6, biomass type, concentration of certain ions, and time after addition. The time-dependent properties of rheologically modified biomass are sensitive to the...

Cellulose nanofibrils (CNFs) are a class of cellulosic nanomaterials with high aspect ratios that can be extracted from various natural sources. Their highly crystalline structures provide the nanofibrils with excellent mechanical and thermal properties. The main challenges of CNFs in nanocomposite applications are associated with their high hydrophilicity, which makes CNFs incompatible with hydrophobic polymers. In this study, highly transparent and toughened poly(methyl methacrylate) (PMMA) nanocomposite films were prepared using various percentages of CNFs covered with surface carboxylic...

The most popular use of wood–plastic composite (WPC) members in the United States has been as outdoor decking material in residential construction. If the use of these products expands into more structural applications, such as beams and joists, it is imperative that the material’s mechanical behavior be understood. Since most of the potential structural uses of this material are as flexural members, it is particularly important that the response to this mode of loading is well characterized. Like many filled polymers, WPCs are anisotropic and bimodal, and thus their shear and two axial...

The USDA Forest Service Forest Inventory and Analysi (FIA) program collects data on a wealth of variables related to trees in forests. Some of these trees produce nontimber forest products (NTFPs) (e.g., fruit, bark and sap) that are harvested for culinary, decorative, building, and medicinal purposes. At least 11 tree species inventoried by FIA are valued for their bark. For example, slippery elm (Ulmus rubra Muhl.) is included in FIA forest inventories, and the bark is used for its medicinal value. Despite widespread use of NTFPs, little quantitative information about abundance, distribut...

The Virginia landscape supports a remarkable diversity of forests, from maritime dunes, swamp forests, and pine savannas of the Atlantic coastal plain, to post-agricultural pine-hardwood forests of the piedmont, to mixed oak, mixed-mesophytic, northern hardwood, and high elevation conifer forests in Appalachian mountain provinces. Virginia’s forests also have been profoundly shaped by disturbance. Chestnut blight, hemlock woolly adelgid, emerald ash borer, and other pests have caused declines or functional extirpation of foundation species. Invasive plants like multiflora rose, Oriental...

Commercial, residential and ranch development combined with pressures from grazing, foraging and pests have decimated Engelmann oak (Quercus engelmannii) populations, resulting in this species being designated as vulnerable by the International Union for Conservation of Nature Red List of Threatened SpeciesTM. Los Angeles County Arboretum and Botanic Garden has the largest population of Engelmann oak in Los Angeles County and therefore has a responsibility to conserve and manage it, ensuring the grove’s long-term survival. To achieve this goal, the arboretum has adopted a four-phase...

The National Historic Covered Bridge Preservation Program (NHCBP), sponsored by the Federal Highway Administration (FHWA), was established to preserve the covered timber bridge structures that were constructed in the early 1800s. Today, many of the approximately 880 covered timber bridges still in existence in the United States are closed to vehicular traffic; furthermore, a large percentage of the remaining bridges open to traffic are restricted by load postings. Unfortunately, there are no current load-rating standards for covered timber bridges, so engineers do not have many resources...

Natural communities near freshwater hydrological features provide important ecosystem functions and services. As human populations increase, forested landscapes become increasingly fragmented and deforested, which may result in a loss of the functions and services they provide. To investigate the current state of forested natural communities in the rapidly urbanizing Tampa Bay Watershed, this study examined a systematic random sample of fixed radius 0.04 hectare (0.10 acre) plots that were located within 15.2 meters of a hydrologic feature. These 85 plots were further stratified based on...

We document the elevational range expansions of two Nicaraguan bird species, scaled pigeon (Patagioenas speciosa) and collared plover (Charadrius collaris). The previously reported elevational range of Patagioenas speciosa was sea level to 600 m. We observed the species in shade coffee at Santa Maura farm at an elevation of 1115 masl. Historically, the second species, Charadrius collaris, was known to occur in Nicaragua in coastal and wetland habitat at elevations not exceeding 50 m. On two occasions, the specie was observed in lacustrine habitat (Lake Apanás) at an elevation of 960 m, not...