544 research outputs found
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Plant hydraulic traits reveal islands as refugia from worsening drought.
Relatively mesic environments within arid regions may be important conservation targets as 'climate change refugia' for species persistence in the face of worsening drought conditions. Semi-arid southern California and the relatively mesic environments of California's Channel Islands provide a model system for examining drought responses of plants in potential climate change refugia. Most methods for detecting refugia are focused on 'exposure' of organisms to certain abiotic conditions, which fail to assess how local adaptation or acclimation of plant traits (i.e. 'sensitivity') contribute to or offset the benefits of reduced exposure. Here, we use a comparative plant hydraulics approach to characterize the vulnerability of plants to drought, providing a framework for identifying the locations and trait patterns that underlie functioning climate change refugia. Seasonal water relations, xylem hydraulic traits and remotely sensed vegetation indices of matched island and mainland field sites were used to compare the response of native plants from contrasting island and mainland sites to hotter droughts in the early 21st century. Island plants experienced more favorable water relations and resilience to recent drought. However, island plants displayed low plasticity/adaptation of hydraulic traits to local conditions, which indicates that relatively conserved traits of island plants underlie greater hydraulic safety and localized buffering from regional drought conditions. Our results provide an explanation for how California's Channel Islands function as a regional climate refugia during past and current climate change and demonstrate a physiology-based approach for detecting potential climate change refugia in other systems
Apollo Lunar Sample Integration into Google Moon: A New Approach to Digitization
The Google Moon Apollo Lunar Sample Data Integration project is part of a larger, LASER-funded 4-year lunar rock photo restoration project by NASA s Acquisition and Curation Office [1]. The objective of this project is to enhance the Apollo mission data already available on Google Moon with information about the lunar samples collected during the Apollo missions. To this end, we have combined rock sample data from various sources, including Curation databases, mission documentation and lunar sample catalogs, with newly available digital photography of rock samples to create a user-friendly, interactive tool for learning about the Apollo Moon sample
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Early, intensive marine resource exploitation by Middle Stone Age humans at Ysterfontein 1 rockshelter, South Africa
Modern human behavioral innovations from the Middle Stone Age (MSA) include the earliest indicators of full coastal adaptation evidenced by shell middens, yet many MSA middens remain poorly dated. We apply Ā²Ā³ā°Th/U burial dating to ostrich eggshells (OES) from Ysterfontein 1 (YFT1, Western Cape, South Africa), a stratified MSA shell midden. Ā²Ā³ā°Th/U burial ages of YFT1 OES are relatively precise (median Ā± 2.7%), consistent with other age constraints, and preserve stratigraphic principles. Bayesian ageādepth modeling indicates YFT1 was deposited between 119.9 to 113.1 thousand years ago (ka) (95% CI of model ages), and the entire 3.8 m thick midden may have accumulated within ā¼2,300 y. Stable carbon, nitrogen, and oxygen isotopes of OES indicate that during occupation the local environment was dominated by Cā vegetation and was initially significantly wetter than at present but became drier and cooler with time. Integrating archaeological evidence with OES Ā²Ā³ā°Th/U ages and stable isotopes shows the following: 1) YFT1 is the oldest shell midden known, providing minimum constraints on full coastal adaptation by ā¼120 ka; 2) despite rapid sea-level drop and other climatic changes during occupation, relative shellfish proportions and sizes remain similar, suggesting adaptive foraging along a changing coastline; 3) the YFT1 lithic technocomplex is similar to other west coast assemblages but distinct from potentially synchronous industries along the southern African coast, suggesting human populations were fragmented between seasonal rainfall zones; and 4) accumulation rates (up to 1.8 m/ka) are much higher than previously observed for dated, stratified MSA middens, implying more intense site occupation akin to Later Stone Age middens
Coffee and shade trees show complementary use of soil water in a traditional agroforestry ecosystem
Financial support. This research has been supported by the PAPIIT-UNAM (Mexico) (grant nos. IB100313 and IB100113), the CONACyT (Mexico) (grant no. 187646), the National Science Foundation (US) (grant no. 1313804), and the Scottish Funding Council (UK) (grant no. SF10192). Author contributions. LEMV designed the experiment. LEMV, MSAB and FH collected the field data. MSAB performed all the Bayesian mixing model analysis. JG contributed in the data analysis. LEMV prepared the first draft of the manuscript. FH, MSAB and JG edited and commented on the manuscript several times, and TED carried out the final revision. Later, all the co-authors contributed with revisions. Data can be accessed at https://doi.org/10.5063/F1MS3R3J (MuƱoz-Villers et al., 2020).Peer reviewedPublisher PD
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Sulfur isotopes reveal agricultural changes to the modern sulfur cycle
The environmental fates and consequences of intensive sulfur (S) applications to croplands are largely unknown. In this study, we used S stable isotopes to identify and trace agricultural S from field-to-watershed scales, an initial and timely step toward constraining the modern S cycle. We conducted our research within the Napa River Watershed, California, US, where vineyards receive frequent fungicidal S sprays. We measured soil and surface water sulfate concentrations ([SO42−]) and stable isotopes (δ34S–SO42−), which we refer to in combination as the 'S fingerprint'. We compared samples collected from vineyards and surrounding forests/grasslands, which receive background atmospheric and geologic S sources. Vineyard δ34S–SO42− values were 9.9 ± 5.9‰ (median ± interquartile range), enriched by ∼10‰ relative to forests/grasslands (−0.28 ± 5.7‰). Vineyards also had roughly three-fold higher [SO42−] than forests/grasslands (13.6 and 5.0 mg SO42−–S l−1, respectively). Napa River δ34S–SO42− values, reflecting the watershed scale, were similar to those from vineyards (10.5 ± 7.0‰), despite vineyard agriculture constituting only ∼11% of the watershed area. Combined, our results provide important evidence that agricultural S is traceable at field-to-watershed scales, a critical step toward determining the consequences of agricultural alterations to the modern S cycle.
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A framework to study and predict functional trait syndromes using phylogenetic and environmental data
Traits do not evolve in isolation but often as part of integrated trait syndromes, yet the relative contributions of environmental effects and evolutionary history on traits and their correlations are not easily resolved.In the present study, we develop a methodological framework to elucidate eco-evolutionary patterns in functional trait syndromes. We do so by separating the amount of variance and covariance related to phylogenetic heritage and environmental variables (environmental phylogenetic conservatism), only phylogenetic heritage (non-attributed phylogenetic conservatism) and only to environmental variables (evolutionarily labile environmental effects). Varianceācovariance structures of trait syndromes are displayed as networks. We then use this framework to guide a newly derived imputation method based on machine learning models that predict trait values for unsampled taxa, considering environmental and phylogenetic information as well as trait covariation. TrEvol is presented as an R package providing a unified set of methodologies to study and predict multivariate trait patterns and improve our capacity to impute trait values.To illustrate its use, we leverage both simulated data and species-level traits related to hydraulics and the leaf economics spectrum, in relation to an aridity index, demonstrating that most trait correlations can be attributed to environmental phylogenetic conservatism.This conceptual framework can be employed to examine issues ranging from the evolution of trait adaptation at different phylogenetic depths to intraspecific trait variation
Revisiting plant hydrological niches: the importance of atmospheric resources for groundārooted plants
Tree-ring Isotopes Adjacent to Lake Superior Reveal Cold Winter Anomalies for the Great Lakes Region of North America
Tree-ring carbon isotope discrimination (Ī13C) and oxygen isotopes (Ī“18O) collected from white pine (Pinus strobus) trees adjacent to Lake Superior show potential to produce the first winter-specific paleoclimate reconstruction with inter-annual resolution for this region. Isotopic signatures from 1976 to 2015 were strongly linked to antecedent winter minimum temperatures (Tmin), Lake Superior peak ice cover, and regional to continental-scale atmospheric winter pressure variability including the North American Dipole. The immense thermal inertia of Lake Superior underlies the unique connection between winter conditions and tree-ring Ī13C and Ī“18O signals from the following growing season in trees located near the lake. By combining these signals, we demonstrate feasibility to reconstruct variability in Tmin, ice cover, and continental-scale atmospheric circulation patterns (r ā„ 0.65, P \u3c 0.001)
Increasing Employee Awareness of the Signs and Symptoms of Heart Attack and the Need to Use 911 in a State Health Department
INTRODUCTION: Early recognition of the signs and symptoms of a heart attack can lead to reduced morbidity and mortality. METHODS: A workplace intervention was conducted among 523 Montana state health department employees in 2003 to increase awareness of the signs and symptoms of heart attack and the need to use 911. All employees received an Act in Time to Heart Attack Signs brochure and wallet card with their paychecks. Act in Time posters were placed in key workplace areas. A weekly e-mail message, including a contest entry opportunity addressing the signs and symptoms of heart attack, was sent to all employees. Baseline and follow-up telephone surveys were conducted to evaluate intervention effectiveness. RESULTS: Awareness of heart attack signs and symptoms and the need to call 911 increased significantly among employees from baseline to follow-up: pain or discomfort in the jaw, neck, or back (awareness increased from 69% to 91%); feeling weak, light-headed, or faint (awareness increased from 79% to 89%); call 911 if someone is having a heart attack or stroke (awareness increased from 84% to 90%). Awareness of chest pain, pain or discomfort in the arms or shoulders, and shortness of breath were more than 90% at baseline and did not increase significantly at follow-up. At baseline, 69% of respondents correctly reported five or more of the signs and symptoms of heart attack; 89% reported correctly at follow-up. CONCLUSION: This low-cost workplace intervention increased awareness of the signs and symptoms of heart attack and the need to call 911
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