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Closing a gap in tropical forest biomass estimation: taking crown mass variation into account in pantropical allometries
Get PDFAccurately monitoring tropical forest carbon stocks is a challenge that remains outstanding. Allometric models that consider tree diameter, height and wood density as predictors are currently used in most tropical forest carbon studies. In particular, a pantropical biomass model has been widely used for approximately a decade, and its most recent version will certainly constitute a reference model in the coming years. However, this reference model shows a systematic bias towards the largest trees. Because large trees are key drivers of forest carbon stocks and dynamics, understanding the origin and the consequences of this bias is of utmost concern. In this study, we compiled a unique tree mass data set of 673 trees destructively sampled in five tropical countries (101 trees > 100 cm in diameter) and an original data set of 130 forest plots (1 ha) from central Africa to quantify the prediction error of biomass allometric models at the individual and plot levels when explicitly taking crown mass variations into account or not doing so. We first showed that the proportion of crown to total tree aboveground biomass is highly variable among trees, ranging from 3 to 88 %. This proportion was constant on average for trees 1 Mg) and reduced the range of plot-level error (in %) from [−23; 16] to [0; 10]. The disproportionally higher allocation of large trees to crown mass may thus explain the bias observed recently in the reference pantropical model. This bias leads to far-from-negligible, but often overlooked, systematic errors at the plot level and may be easily corrected by taking a crown mass proxy for the largest trees in a stand into account, thus suggesting that the accuracy of forest carbon estimates can be significantly improved at a minimal cost.This is the publisher’s final pdf. The published article is copyrighted by the author(s) and published by Copernicus Publications on behalf of the European Geosciences Union. The published article can be found at: http://www.biogeosciences.net
First record of the genus Pseudopilolabus Legalov, 2003 (Coleoptera: Attelabidae) in Dominican amber
Get PDFA new weevil species (urn:lsid:zoobank.org: act:2D5E9E4A-A250-4D0A-AF69-CF4753436686), Pseudopilolabus othnius Poinar, Brown and Legalov, sp. nov. (Coleoptera: Attelabidae), is described from Dominican amber. The new species is close to the extant P. viridanus (Gyllenhal, 1839) and P. splendens (Gyllenhal, 1839) but differs by having a bronzed body, narrower and more convex elytral intervals, long antennae reaching the middle of the pronotum, and weakly convex eyes; from P. rugiceps (Voss, 1925) it differs by having a smoother pronotum without transverse rugosity; from P. chiriquensis (Hamilton, 1994) it differs by having indistinctly protuberant humeri and the elytra nearly parallel from the humeri to the midpoint. The fossil weevil is the first record of the tribe Pilolabini (Attelabidae) from the West Indies and the first record of the Attelabidae from any amber source
WagnerClimateSeasonalityLimits.pdf
No full textThe seasonal climate drivers of the carbon cycle in tropical forests remain poorly known, although these forests account for more carbon assimilation and storage than any other terrestrial ecosystem. Based on a unique combination of seasonal pan-tropical data sets from 89 experimental sites (68 include aboveground wood productivity measurements and 35 litter productivity measurements), their associated canopy photosynthetic capacity (enhanced vegetation index, EVI) and climate, we ask how carbon assimilation and aboveground allocation are related to climate seasonality in tropical forests and how they interact in the seasonal carbon cycle. We found that canopy photosynthetic capacity seasonality responds positively to precipitation when rainfall is < 2000 mm yr⁻¹ (water-limited forests) and to radiation otherwise (light-limited forests). On the other hand, independent of climate limitations, wood productivity and litterfall are driven by seasonal variation in precipitation and evapotranspiration, respectively. Consequently, light-limited forests present an asynchronism between canopy photosynthetic capacity and wood productivity. First-order control by precipitation likely indicates a decrease in tropical forest productivity in a drier climate in water-limited forest, and in current light-limited forest with future rainfall < 2000 mm yr⁻¹
Seasonal cycle of surface ocean pCO₂ on the Oregon shelf
Get PDFPrevious work has shown that the Oregon shelf is a sink for atmospheric carbon dioxide (CO₂) during the upwelling season; however, until now, summertime variability in CO₂ exchange and sign of the flux for the rest of the year were unknown. Observations of the partial pressure of CO₂ (pCO₂) in surface waters from August 2007 to May 2010 from ships and a buoy were used with historical data to produce a composite seasonal cycle for the central Oregon midshelf. These data indicate that the region is highly variable, at times being either a sink or strong source for atmospheric CO₂. Interannual wind variability was an important determining factor in shaping the sink/source nature of this system. Late summer and early autumn was most variable relative to the rest of the year. Winter pCO₂ was near or slightly below atmospheric levels. Strong shelf-wide undersaturated conditions were first observed in early spring and lasted until the upwelling season became developed. Peak upwelling season pCO₂ ranged from 1000 μatm. In July 2008, ship and buoy data revealed previously unobserved high-pCO₂ waters (∼1000 μatm) at the surface. These conditions persisted for nearly 2 months and drove this system to be only a weak net annual atmospheric CO₂ sink of −0.3 ± 6.8 mol m⁻² yr⁻¹. These data showed, for the first time, the seasonal cycle of surface ocean pCO₂ on the central Oregon midshelf and the impact of heretofore undocumented pCO₂ levels on an estimate of sea-air CO₂ flux for this region.This is the publisher's final pdf. The published article is copyrighted by American Geophysical Union and can be found at: http://www.agu.org/journals/jc
Continuous flow mesofluidic synthesis of Cu₂ZnSnS₄ nanoparticle inks
Get PDFCopper zinc tin sulfide (CZTS) nanoparticles were synthesized using ethylene glycol as a solvent via a continuous flow mesofluidic reactor. In this study reaction temperature, residence time, and precursor concentrations were used to control CZTS composition. It was found that CZTS initially forms by the nucleation of Cu₂₋ₓS with subsequent incorporation of the remaining metal species as dictated by the cation reactivity, where Cu⁺>Sn⁺⁴>Zn⁺². CZTS nanoparticle films annealed in a selenium-containing atmosphere resulted in the formation of copper zinc tin selenide nanoparticles with much larger particle sizes.This is the authors' final peer-reviewed manuscript. The version of record is copyrighted by Elsevier and can be found here: http://www.journals.elsevier.com/materials-letters
Ambient Hydrolysis Deposition of TiO₂ in Nanoporous Carbon and the Converted TiN/Carbon Capacitive Electrode
Get PDFDespite the considerable advances of deposition technologies, it remains a significant challenge to form conformal deposition on surface of nanoporous carbons. Here, we introduce a new ambient hydrolysis deposition method that employs and controls pre-adsorbed water vapor on nanoporous carbons to define the deposition of TiO₂. We converted the deposited TiO₂ into TiN via a nitridation process. The metallic-TiN-coated porous carbon exhibits superior kinetic performance as an electrode in electrical double layer capacitors. The novel deposition method provides a general solution for surface engineering on nanostructured carbons, which may result in a strong impact on the fields of energy storage and other disciplines
Making Science Accessible
No full textMy work in the Harper Nanotoxicology Lab focuses on science communication. The Harper Lab conducts research to address data gaps regarding the toxicity of micro and nanoplastic in the environment, specifically in aquatic habitats. It is important for the public to understand what the lab does, and how they can be involved in its efforts to decrease plastic pollution. My work consists of tasks like website development, research translation, and the creation of marketing materials like logos and infographics. The targeted audience is eco-conscious individuals interested in sustainable practices. My approach is to take dense and complex research regarding micro and nanoplastics pollution, and convey the importance of the data in reality using accessible language and engaging designs. The value of accessible language in this field is crucial so people without a background in science are still able to comprehend the information presented to them, and they can make informed decisions about their personal plastic consumption. The design aspect incorporates elements like fonts, colors, white space, symbols, pictures, and text to present information that will be useful to the viewer. Finding a balance to the amount of design elements is key because an excess could detract from the information being presented, but an inadequate amount may not grab a viewer’s attention. If useful information is not presented properly, it is just as worthless as useless information. The coherence, appearance, and appropriateness of content and design are major components of science communication, and consequently making science accessible
The COVID-19 pandemic and food insecurity among college students
Get PDFFood insecurity is a common issue among college students in the United States with recent research suggesting that between 10-75% of college students are food insecure. In comparison, an estimated 10.2% of U.S. Households are food insecure. Food insecurity is associated with many negative health outcomes. The purpose of this systematic review is to synthesize the research on the prevalence of and risk factors for food insecurity among college students during the COVID-19 pandemic, and to explore recommended ways to mitigate this public health issue. PubMed was searched using MESH terms, and the presence of key words in the title and abstract were used to determine which articles to review in full. Exclusion criteria were used to narrow down the articles further and 17 articles were included for review. The results of this review were inconclusive on whether food insecurity increased, decreased or stayed the same among college students during the pandemic. Being non-White race was associated with increased risk for food insecurity during the pandemic. Changes in housing were associated with either an increase or decrease in food security depending on whether students experienced an increase in food resources due to the change. Changes in employment were associated with decreases in food security. Several other factors such as changes in shopping habits, having low cooking self-efficacy, being a first-generation college student, and having children or being food insecure prior to the pandemic were associated with food insecurity during the pandemic.Keywords: Food insecurity, undergraduate, college, COVID-1
