Treesearch

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...

The emission of gases that may potentially intensify the greenhouse effect has received special attention due to their ability to raise global temperatures and possibly modify conditions for life on earth. The objectives of this study were the quantification of trace gas flux (N2O, CO2 and CH4) in soils of the lower Amazon basin that are planted with rice and soybean, and the relation of this flux to soil physical and chemical parameters and to precipitation. This study was conducted in agricultural fields planted with rice (Oryza sativa) and soybean (Glycine max), located near the cities...

Carbon nanospheres were synthesized by hydrothermal carbonization (HTC) of four different carbon sources: xylose, glucose, sucrose, and pine wood derived saccharides. The obtained carbon nanospheres were characterized for particle morphology and size, and surface functional groups. Morphological and structural differences among these saccharides derived HTC carbons were clearly observed. Scanning electron microscopy images of carbon nanospheres from HTC of xylose showed uniform spherical particles with diameters around 80 nm, while carbon nanospheres obtained from glucose, sucrose, and...

Superhydrophobic poly(vinyl alcohol) (PVA)/ cellulose nanofibril (CNF) aerogels with a unidirectionally aligned microtubular porous structure were prepared using a unidirectional freeze-drying process, followed by the thermal chemical vapor deposition of methyltrichlorosilane. The silanized aerogels were characterized using various techniques including scanning electron microscopy (SEM), Fourier transform infrared spectroscopy, and contact angle measurements. The structure of the aerogels fully filled with polydimethylsiloxane (PDMS) was confirmed by SEM and optical microscopy. The...

Today’s consumer electronics, such as cell phones, tablets and other portable electronic devices, are typically made of non-renewable, non-biodegradable, and sometimes potentially toxic (for example, gallium arsenide) materials. These consumer electronics are frequently upgraded or discarded, leading to serious environmental contamination. Thus, electronic systems consisting of renewable and biodegradable materials and minimal amount of potentially toxic materials are desirable. Here we report high-performance flexible microwave and digital electronics that consume the smallest amount of...

Fragmentation alters forest canopy structure through various mechanisms, which in turn drive subsequent changes to biogeochemical processes and biological diversity. Using repeated airborne LiDAR (Light Detection and Ranging) mappings, we investigated the size distribution and dynamics of forest canopy gaps across a topical montane forest landscape in Hawaii naturally fragmented by lava >100 yr ago. The combined effects of long-term isolation were evaluated using edge-proximity patterns in the distribution of gaps identified in year 1 ("existing gaps"). In addition, using the data from...

Over a period of about 20 years, the International Institute of Tropical Forestry (the Institute) and its collaborators developed and implemented a facilities plan that included both new and restored facilities. Among the restored facilities, the historic Headquarters Building received a Leadership in Energy and Environmental Design (LEED) Gold certificate, and was praised by the State Historic Preservation Office for the manner under which the restoration was conducted. It is unusual for historic buildings to acquire this certification. New facilities, both at Institute headquarters and...