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Arctic Holocene proxy climate database - new approaches to assessing geochronological accuracy and encoding climate variables
Get PDFWe present a systematic compilation of previously published Holocene proxy climate records from the Arctic. We identified 170 sites from north of 58° N latitude where proxy time series extend back at least to 6 cal ka (all ages in this article are in calendar years before present – BP), are resolved at submillennial scale (at least one value every 400 ± 200 years) and have age models constrained by at least one age every 3000 years. In addition to conventional metadata for each proxy record (location, proxy type, reference), we include two novel parameters that add functionality to the database. First, "climate interpretation" is a series of fields that logically describe the specific climate variable(s) represented by the proxy record. It encodes the proxy–climate relation reported by authors of the original studies into a structured format to facilitate comparison with climate model outputs. Second, "geochronology accuracy score" (chron score) is a numerical rating that reflects the overall accuracy of 14C-based age models from lake and marine sediments. Chron scores were calculated using the original author-reported 14C ages, which are included in this database. The database contains 320 records (some sites include multiple records) from six regions covering the circumpolar Arctic: Fennoscandia is the most densely sampled region (31% of the records), whereas only five records from the Russian Arctic met the criteria for inclusion. The database contains proxy records from lake sediment (60%), marine sediment (32%), glacier ice (5%), and other sources. Most (61%) reflect temperature (mainly summer warmth) and are primarily based on pollen, chironomid, or diatom assemblages. Many (15%) reflect some aspect of hydroclimate as inferred from changes in stable isotopes, pollen and diatom assemblages, humification index in peat, and changes in equilibrium-line altitude of glaciers. This comprehensive database can be used in future studies to investigate the spatio-temporal pattern of Arctic Holocene climate changes and their causes. The Arctic Holocene data set is available from NOAA Paleoclimatology
An elusive ectomycorrhizal fungus reveals itself: a new species of Geopora (Pyronemataceae) associated with Pinus edulis
Get PDFSpecies of the genus Geopora are important ectomycorrhizal associates that can dominate the communities of some plant taxa, such as pinyon pine (Pinus edulis), a widespread tree of the western United States. Several members of the genus Geopora are known only from ectomycorrhizal root tips and thus have not been described formally. The sporocarps of some Geopora species occur infrequently because they depend on wet years for sporulation. In addition, Geopora sporocarps can be small and may be hypogeous at some developmental stage, limiting the opportunities for describing their morphology. Using molecular and morphological data, we have described a new species of fungus, Geopora pinyonensis, which produced ascocarps after unusually high precipitation at a northern Arizona site in summer 2012. Based on analysis of the ITS and nuLSU regions of the rDNA, G pinyonensis is a new species of Geopora. It has small sporocarps and ascospores relative to other members of the genus; however, these morphological features overlap with other species. Using rDNA data from sporocarps and ectomycorrhizal root tips, we show that the sporocarps correspond to an abundant species of ectomycorrhizal fungus associated with pinyon pines that is increasing in abundance in drought-affected landscapes and may promote drought tolerance
Fact sheet: Post-wildfire restoration of structure, composition, and function in southwestern ponderosa pine and warm-dry mixed-conifer forests.
Get PDFPost-fire rehabilitation is separated into short-term, emergency stabilization and long-term restoration measures. The Burned Area Emergency Response (BAER) program includes emergency treatments to stabilize the burned area, protect public health and safety, and reduce the risk of additional damage to valued resources. As opposed to emergency rehabilitation, ecological restoration focuses on assisting the recovery of characteristic ecological structure, process, and function, which requires an understanding of natural range of variability for these key attributes as well as development of reference conditions to guide management activities. In addition, restoration activities demand long-term commitment and evaluation. Given the altered conditions that can follow high-severity fires, successful restoration to a desired state may be difficult and costly. Areas experiencing high-severity fire often exhibit accelerated soil erosion and subsequent loss of soil productivity; expansions or invasions of non-native plant populations; loss of wildlife habitat; damaged watersheds and degraded water quality to connected streams; and/or vegetation type conversion. Attributes of a restored ecosystem include the reestablishment of resilience, forest structure, composition, function, physical environment, and landscape context and integrity
Working Paper 31: Climate Change Impacts on Bark Beetle Outbreaks and the Impact of Outbreaks on Subsequent Fires.
Get PDFThe Insect Bark beetles are small insects that can have profound impacts on forests. While some species of bark beetles primarily attack trees that are recently dead or dying, others attack live, vigorous trees and can cause tree mortality across extensive areas. The Southwest is home to multiple species of bark beetles (Gaylord et al. 2006, Williams et al. 2008). In southwestern ponderosa pine forests the most notable bark beetle species belong to the genus Ips or Dendroctonus. Ecological Role and Impacts Bark beetles and fire share similar roles in southwestern ponderosa pine forests. Similar to fire, bark beetles are natural disturbance agents and help with nutrient redistribution. Tree mortality from bark beetles helps with snag formation, providing vital habitat for cavity nesting birds and bats, among other wildlife. Bark beetles are a food source for other insects and birds. At low bark beetle populations, tree mortality ranges from individual trees to small groups of trees leading to gap formation and increasing forest heterogeneity. Epidemics, or outbreaks, are also part of the natural cycle. In some ecosystems, such as mountain pine beetle in lodgepole pine, the forests are homogenized after these outbreaks, helping to perpetuate lodgepole pine stands (Brown 1975). Historically, epidemics would subside due to excessively cold temperatures or because suitable host material (tree species or preferred diameter range) becomes depleted. Current bark beetle outbreaks in some forest systems are considered unprecedented (Raffa et al. 2008, Bentz et al. 2009). Recent outbreaks appear to be driven by warmer/drier climate, an abundance of overstocked and homogeneous stands caused by past management decisions, or a combination of these and other factors (Raffa et al. 2008, Bentz et al. 2010, Fettig et al. 2013). In essence, large-scale outbreaks are a result of many of the same factors driving catastrophic fires and, consequently, both disturbance agents are having impacts on ecosystems that are often outside of their historic range of variability
How private property protection influences the impact of intellectual property rights on economic growth: Working paper series--14-03
Get PDFAlthough policy makers typically assume a positive relationship between intellectual property rights (IPRs) and economic growth, the empirical evidence on the IPR-growth relationship is rather inconclusive (e.g. Andersen and Konzelmann, 2008). We conjecture in this paper that the weak IPR-growth evidence in previous studies may be due to a neglect of the role of finance markets and private property rights. Our conjecture is motivated by the recent law and finance literature. We test our conjecture with a cross-section of 98 countries and find that once we modify our measure of IPRs to take into account general property rights, there is stronger evidence for a positive relationship between IPRs and economic growth. Our findings not only help explain the IPR-innovation puzzle in Lerner (2009), among others, but also have significant theoretical as well as policy implications
The solar neighborhood. XXXIV. a search for planets orbiting nearby M dwarfs using astrometry
Get PDFAstrometric measurements are presented for seven nearby stars with previously detected planets: six M dwarfs (GJ 317, GJ 667C, GJ 581, GJ 849, GJ 876, and GJ 1214) and one K dwarf (BD-10 -3166). Measurements are also presented for six additional nearby M dwarfs without known planets, but which are more favorable to astrometric detections of low mass companions, as well as three binary systems for which we provide astrometric orbit solutions. Observations have baselines of 3 to 13 years, and were made as part of the RECONS long-term astrometry and photometry program at the CTIO/SMARTS 0.9 m telescope. We provide trigonometric parallaxes and proper motions for all 16 systems, and perform an extensive analysis of the astrometric residuals to determine the minimum detectable companion mass for the 12 M dwarfs not having close stellar secondaries. For the six M dwarfs with known planets, we are not sensitive to planets, but can rule out the presence of all but the least massive brown dwarfs at periods of 2–12 years. For the six more astrometrically favorable M dwarfs, we conclude that none have brown dwarf companions, and are sensitive to companions with masses as low as 1 for periods longer than two years. In particular, we conclude that Proxima Centauri has no Jovian companions at orbital periods of 2–12 years. These results complement previously published M dwarf planet occurrence rates by providing astrometrically determined upper mass limits on potential super-Jupiter companions at orbits of two years and longer. As part of a continuing survey, these results are consistent with the paucity of super-Jupiter and brown dwarf companions we find among the over 250 red dwarfs within 25 pc observed longer than five years in our astrometric program
Genome sequence of Bacillus anthracis STI, a sterne-like Georgian/Soviet vaccine strain
Get PDFThe Bacillus anthracis strain STI is a Soviet vaccine strain that lacks the pXO2 plasmid. Previous data indicate that this isolate forms a new branch within the B. anthracis sub-group originally identified as A. Br.008/009
Notes on your desk and in the cloud: comparing Evernote and OneNote
Get PDFThe article presents a comparison of Evernote digital workspace from Evernote Corp. and Microsoft OneNote digital note-taking app from Microsoft Corp
Fact sheet: Soil seed banks in a mature coniferous forest landscape: Dominance of native perennials and low spatial variability
Get PDFViable seeds stored in soil (soil seed banks) are important features of plant communities that contribute to site potential for restoration and recovery from disturbance (events that disrupt an ecosystem such as fire or logging). Seed banks typically contain few seeds of late-successional species. Rather, forest seed banks are normally dominated by early successional species, often short-lived (e.g., annual) and "ruderal" (weedy) species with abilities to rapidly colonize disturbed areas. When disturbance reduces the tree overstory, these species recruit, produce seed to replenish seed banks, and then often become sparse or absent aboveground as forest canopy increases. On the other hand, aboveground species of a late-successional forest often do not rely on soil seed banks. Instead, these species are usually long-lived, rendering persistent seed banks of minimal importance to their population dynamics. As a result, seed banks of late-successional forests are generally dominated by species other than those of the existing mature vegetation. Soil seed bank samples were collected on the east side of the Spring Mountains in southern Nevada (Figure 1, page 2). We used a network of Terrestrial Ecological Unit Inventory (TEUI) sites established by the U.S. Forest Service to characterize variability in environmental gradients and vegetation across the landscape. These sites were established in the centers of mapping units defined on the basis of similarity in climate, soil parent material and vegetation. With much of the study area roadless and in designated wilderness, human disturbance at the sites over the past 50-100 years is not extensive. Sample sites encompassed broad environmental and vegetation gradients across the landscape, ranging in elevation from 7,039 feet to 10,798 feet in forest types that included pinyon-juniper, pinyon pine, ponderosa pine, mixed conifer and bristlecone pine