Continuing fire regimes in remote forest of Grand Canyon National Park

Ponderosa pine forests in which frequent fire regimes continue up to the present would be invaluable points of reference for assessing natural ecological attributes. A few remote forests on the North Rim of Grand Canyon National Park come close to this ideal: never-harvested, distant from human communities and fire suppression resources, and with several low-intensity fires in the past century—a highly unusual recent fire regime in the Southwest. Recent fires appear to have played a crucial role in preventing the increases in forest density that characterize most southwestern pine forests. The study sites are not unaffected by the ecological changes associated with settlement, but they do present an important reference resource for study and management of ponderosa pine ecosystems

News on the Machtenstein H5 ordinary chondrite

第6回極域科学シンポジウム[OA] 南極隕石11月16日（月）　国立極地研究所１階交流アトリウ

Changes in ponderosa pine forests of the Mt. Trumbull Wilderness

Ponderosa pine forests in the Mt. Trumbull Wilderness on the Arizona Strip have become dense with young trees and highly susceptible to catastrophic wildfire due to exclusion of the natural frequent-fire regime. As part of a broader regional ecological restoration study, the Mt. Trumbull Wilderness was sampled for fire scarred trees, vegetation, and fuels in 1997 and 1999. Reconstructed fire histories show that fires recurred about every 4.4 years prior to settlement, with larger fires burning every 9.5 years. Frequent fires ceased after 1863 in the Mt. Trumbull Wilderness, coincident with the time of Euro-American settlement around 1870, beginning a fire-free period that has lasted up to the present except for a few small fires and a larger 1989 wildfire. Current forests are dense, averaging approximately 1,200 trees/ha, and dominated by small trees. Throughout the wilderness, tree canopy cover averages over 65(percent) and tree basal area is high, 35- 36 m2/ha. Understory plant cover is about 20(percent) and understory species diversity averages 11.4 species/sample plot. Living and dead fuels, including plants, woody debris, and the forest floor, will easily support high-intensity wildfires. In contrast, the presettlement forest was relatively open, with tree density of approximately 62 trees/ha and basal area averaging 8.9 m2/ha, dominated by large ponderosa pine trees. In ecological terms, prospects are good for restoring the Mt. Trumbull Wilderness to emulate the ecological structure and fire disturbance regime of the presettlement reference condition. The current forest condition is perhaps least affected by recent degradation of any site in the Uinkaret Mountains. However, ecological information is only one component contributing to the debate over appropriate management values and practices in wilderness areas on public lands

Transport of hop aroma compounds across Caco-2 monolayers

Although being reported and used as a sedative remedy for several years, the bioactive principle of hop preparations is still not decisively clarified. Understanding absorption and transformation processes of potential physiologically active constituents is essential to evaluate the likeliness of biological effects on humans. Therefore, single hop aroma compounds as well as digestive transformation products thereof have been investigated in view of their human intestinal absorption, applying Caco-2 transport experiments as well as investigations on potential biotransformation processes. Selective and sensitive identification and quantification were thereby achieved by application of two-dimensional high resolution gas chromatography-mass spectrometry in conjunction with stable isotope dilution analysis, leading to the determination of apparent permeability values by different mathematical approaches considering sink and non-sink conditions. Overall, calculated permeability values ranged from 2.6 × 10−6 to 1.8 × 10−4 cm s−1 with all mathematical approaches, indicating high absorption potential and almost complete bioavailability for all tested compounds with hydroxyl-functionalities. Considering this high permeability together with the high lipophilicity of these substances, a passive transcellular uptake route can be speculated. Investigated sesquiterpenes and β-myrcene showed flat absorption profiles while the investigated esters showed decreasing profiles. In view of the lipophilic and volatile nature of the investigated substances, special attention was paid to recovery and mass balance determination. Furthermore, in the course of the transport experiments of 1-octen-3-ol and 3-methyl-2-buten-1-ol, additional biotransformation products were observed, namely 3-octanone and 3-methyl-2-butenal, respectively. The absence of these additional substances in control experiments strongly indicates an intestinal first-pass metabolism of the α,β-unsaturated alcohols 1-octen-3-ol and 3-methyl-2-buten-1-ol in Caco-2 cells

Managing Volunteer Retirement among Older Adults: Perspectives of Volunteer Administrators

A large body of quantitative evidence demonstrates a link between volunteering and improved well-being, especially among older adults. Yet the research evidence pointing to the purported benefits of volunteering does not adequately address the unique experiences of older volunteers, nor does it address the ways in which working with them impacts the work of volunteer administrators. As the proportion of those aged 65 and older increases, older adults are poised to play an even greater role as volunteers than ever before, representing both unparalleled opportunity and potential new challenges for volunteer administrators. One such challenge includes how to manage older adults’ decisions to withdraw or retire from volunteering, which has an impact on the succession planning of the volunteer workforce. This article presents the results of a recent survey of volunteer administrators who share current policies and perspectives about volunteer retirement. These practitioner viewpoints provide important insights for both volunteer management and future research

Ecological restoration marking guidelines for ponderosa pine restoration areas

This document is a full restoration marking guide for the Flagstaff Urban/Wildland Interface with modifications to increase spatial clumpiness of residual trees