scholarly journals Herbarium specimens reveal substantial and unexpected variation in phenological sensitivity across the eastern United States

2018 ◽  
Vol 374 (1763) ◽  
pp. 20170394 ◽  
Author(s):  
Daniel S. Park ◽  
Ian Breckheimer ◽  
Alex C. Williams ◽  
Edith Law ◽  
Aaron M. Ellison ◽  
...  
Keyword(s):  
United States ◽  
Climatic Change ◽  
Large Scale ◽  
Critical Role ◽  
Flowering Plant ◽  
Reproductive Phenology ◽  
Herbarium Specimens ◽  
Eastern United States ◽  
Regional Patterns ◽  
Continental Scale

Phenology is a key biological trait that can determine an organism's survival and provides one of the clearest indicators of the effects of recent climatic change. Long time-series observations of plant phenology collected at continental scales could clarify latitudinal and regional patterns of plant responses and illuminate drivers of that variation, but few such datasets exist. Here, we use the web tool CrowdCurio to crowdsource phenological data from over 7000 herbarium specimens representing 30 diverse flowering plant species distributed across the eastern United States. Our results, spanning 120 years and generated from over 2000 crowdsourcers, illustrate numerous aspects of continental-scale plant reproductive phenology. First, they support prior studies that found plant reproductive phenology significantly advances in response to warming, especially for early-flowering species. Second, they reveal that fruiting in populations from warmer, lower latitudes is significantly more phenologically sensitive to temperature than that for populations from colder, higher-latitude regions. Last, we found that variation in phenological sensitivities to climate within species between regions was of similar magnitude to variation between species. Overall, our results suggest that phenological responses to anthropogenic climate change will be heterogeneous within communities and across regions, with large amounts of regional variability driven by local adaptation, phenotypic plasticity and differences in species assemblages. As millions of imaged herbarium specimens become available online, they will play an increasingly critical role in revealing large-scale patterns within assemblages and across continents that ultimately can improve forecasts of the impacts of climatic change on the structure and function of ecosystems. This article is part of the theme issue ‘Biological collections for understanding biodiversity in the Anthropocene’.

scholarly journals Continental-scale patterns of Cecropia reproductive phenology: evidence from herbarium specimens

2011 ◽  
Vol 278 (1717) ◽  
pp. 2437-2445 ◽  
Author(s):  
Paul-Camilo Zalamea ◽  
François Munoz ◽  
Pablo R. Stevenson ◽  
C. E. Timothy Paine ◽  
Carolina Sarmiento ◽  
...  
Keyword(s):  
Large Scale ◽  
Field Survey ◽  
Spatial Scales ◽  
Field Studies ◽  
Plant Phenology ◽  
Reproductive Phenology ◽  
Herbarium Specimens ◽  
Climatic Regions ◽  
Continental Scale ◽  
Flowering Behaviour

Plant phenology is concerned with the timing of recurring biological events. Though phenology has traditionally been studied using intensive surveys of a local flora, results from such surveys are difficult to generalize to broader spatial scales. In this study, contrastingly, we assembled a continental-scale dataset of herbarium specimens for the emblematic genus of Neotropical pioneer trees, Cecropia , and applied Fourier spectral and cospectral analyses to investigate the reproductive phenology of 35 species. We detected significant annual, sub-annual and continuous patterns, and discuss the variation in patterns within and among climatic regions. Although previous studies have suggested that pioneer species generally produce flowers continually throughout the year, we found that at least one third of Cecropia species are characterized by clear annual flowering behaviour. We further investigated the relationships between phenology and climate seasonality, showing strong associations between phenology and seasonal variations in precipitation and temperature. We also verified our results against field survey data gathered from the literature. Our findings indicate that herbarium material is a reliable resource for use in the investigation of large-scale patterns in plant phenology, offering a promising complement to local intensive field studies.

scholarly journals Variability of Cloudiness over Mountain Terrain in the Western United States

2017 ◽  
Vol 18 (5) ◽  
pp. 1227-1245 ◽  
Author(s):  
Edwin Sumargo ◽  
Daniel R. Cayan
Keyword(s):  
United States ◽  
Large Scale ◽  
Spatial Scales ◽  
High Elevation ◽  
Empirical Orthogonal Functions ◽  
Western United States ◽  
Spatial And Temporal Variability ◽  
Regional Patterns ◽  
Cloud Albedo

Abstract This study investigates the spatial and temporal variability of cloudiness across mountain zones in the western United States. Daily average cloud albedo is derived from a 19-yr series (1996–2014) of half-hourly Geostationary Operational Environmental Satellite (GOES) images. During springtime when incident radiation is active in driving snowmelt–runoff processes, the magnitude of daily cloud variations can exceed 50% of long-term averages. Even when aggregated over 3-month periods, cloud albedo varies by ±10% of long-term averages in many locations. Rotated empirical orthogonal functions (REOFs) of daily cloud albedo anomalies over high-elevation regions of the western conterminous United States identify distinct regional patterns, wherein the first five REOFs account for ~67% of the total variance. REOF1 is centered over Northern California and Oregon and is pronounced between November and March. REOF2 is centered over the interior northwest and is accentuated between March and July. Each of the REOF/rotated principal components (RPC) modes associates with anomalous large-scale atmospheric circulation patterns and one or more large-scale teleconnection indices (Arctic Oscillation, Niño-3.4, and Pacific–North American), which helps to explain why anomalous cloudiness patterns take on regional spatial scales and contain substantial variability over seasonal time scales.

scholarly journals Seasonal prediction of US summertime ozone using statistical analysis of large scale climate patterns

2017 ◽  
Vol 114 (10) ◽  
pp. 2491-2496 ◽  
Author(s):  
Lu Shen ◽  
Loretta J. Mickley
Keyword(s):  
United States ◽  
Large Scale ◽  
Surface Ozone ◽  
Tropical Atlantic ◽  
Eastern United States ◽  
Northeast Pacific ◽  
Ozone Concentrations ◽  
Climate Patterns ◽  
Ocean Atmosphere ◽  
Ozone Episodes

We develop a statistical model to predict June–July–August (JJA) daily maximum 8-h average (MDA8) ozone concentrations in the eastern United States based on large-scale climate patterns during the previous spring. We find that anomalously high JJA ozone in the East is correlated with these springtime patterns: warm tropical Atlantic and cold northeast Pacific sea surface temperatures (SSTs), as well as positive sea level pressure (SLP) anomalies over Hawaii and negative SLP anomalies over the Atlantic and North America. We then develop a linear regression model to predict JJA MDA8 ozone from 1980 to 2013, using the identified SST and SLP patterns from the previous spring. The model explains ∼45% of the variability in JJA MDA8 ozone concentrations and ∼30% variability in the number of JJA ozone episodes (>70 ppbv) when averaged over the eastern United States. This seasonal predictability results from large-scale ocean–atmosphere interactions. Warm tropical Atlantic SSTs can trigger diabatic heating in the atmosphere and influence the extratropical climate through stationary wave propagation, leading to greater subsidence, less precipitation, and higher temperatures in the East, which increases surface ozone concentrations there. Cooler SSTs in the northeast Pacific are also associated with more summertime heatwaves and high ozone in the East. On average, models participating in the Atmospheric Model Intercomparison Project fail to capture the influence of this ocean–atmosphere interaction on temperatures in the eastern United States, implying that such models would have difficulty simulating the interannual variability of surface ozone in this region.

scholarly journals Structure and Migration in U.S. Blumeria graminis f. sp. tritici Populations

2016 ◽  
Vol 106 (3) ◽  
pp. 295-304 ◽  
Author(s):  
Christina Cowger ◽  
Ryan Parks ◽  
Evsey Kosman
Keyword(s):  
Ssr Markers ◽  
Large Scale ◽  
Isolation By Distance ◽  
Blumeria Graminis ◽  
Snp Markers ◽  
Eastern United States ◽  
Long Distance ◽  
Continental Scale ◽  
South Central ◽  
Haplotypic Diversity

While wheat powdery mildew occurs throughout the south-central and eastern United States, epidemics are especially damaging in the Mid-Atlantic states. The structure of the U.S. Blumeria graminis f. sp. tritici population was assessed based on a sample of 238 single-spored isolates. The isolates were collected from 16 locations in 12 states (18 site-years) as chasmothecial samples in 2003 or 2005, or as conidial samples in 2007 or 2010. DNA was evaluated using nine single nucleotide polymorphism (SNP) markers in four housekeeping genes, and 10 simple sequence repeat (SSR) markers. The SSR markers were variably polymorphic, with allele numbers ranging from 3 to 39 per locus. Genotypic diversity was high (210 haplotypes) and in eight of the site-years, every isolate had a different SSR genotype. SNP haplotypic diversity was lower; although 15 haplotypes were identified, the majority of isolates possessed one of two haplotypes. The chasmothecial samples showed no evidence of linkage disequilibrium (P = 0.36), while the conidial samples did (P = 0.001), but the two groups had nearly identical mean levels of genetic diversity, which was moderate. There was a weakly positive relationship between genetic distance and geographic distance (R2 = 0.25, P = 0.001), indicating modest isolation by distance. Most locations in the Mid-Atlantic and Great Lakes regions clustered together genetically, while Southeast locations formed a distinct but adjacent cluster; all of these were genetically separated from Southern Plains locations and an intermediate location in Kentucky. One-way migration was detected at a rate of approximately five individuals per generation from populations west of the Appalachian Mountains to those to the east, despite the fact that the Atlantic states experience more frequent and damaging wheat mildew epidemics. Overall, the evidence argues for a large-scale mosaic of overlapping populations that re-establish themselves from local sources, rather than continental-scale extinction and re-establishment, and a low rate of long-distance dispersal roughly from west to east, consistent with prevailing wind directions.

scholarly journals A Dynamical and Statistical Characterization of U.S. Extreme Precipitation Events and Their Associated Large-Scale Meteorological Patterns

2017 ◽  
Vol 30 (4) ◽  
pp. 1307-1326 ◽  
Author(s):  
Siyu Zhao ◽  
Yi Deng ◽  
Robert X. Black
Keyword(s):  
United States ◽  
Extreme Precipitation ◽  
Large Scale ◽  
Warm Season ◽  
Base Function ◽  
Regional Patterns ◽  
Statistical Characterization ◽  
Climate System Model ◽  
Extreme Precipitation Events ◽  
Precipitation Events

Abstract Regional patterns of extreme precipitation events occurring over the continental United States are identified via hierarchical cluster analysis of observed daily precipitation for the period 1950–2005. Six canonical extreme precipitation patterns (EPPs) are isolated for the boreal warm season and five for the cool season. The large-scale meteorological pattern (LMP) inducing each EPP is identified and used to create a “base function” for evaluating a climate model’s potential for accurately representing the different patterns of precipitation extremes. A parallel analysis of the Community Climate System Model, version 4 (CCSM4), reveals that the CCSM4 successfully captures the main U.S. EPPs for both the warm and cool seasons, albeit with varying degrees of accuracy. The model’s skill in simulating each EPP tends to be positively correlated with its capability in representing the associated LMP. Model bias in the occurrence frequency of a governing LMP is directly related to the frequency bias in the corresponding EPP. In addition, however, discrepancies are found between the CCSM4’s representation of LMPs and EPPs over regions such as the western United States and Midwest, where topographic precipitation influences and organized convection are prominent, respectively. In these cases, the model representation of finer-scale physical processes appears to be at least equally important compared to the LMPs in driving the occurrence of extreme precipitation.

scholarly journals A UT/LS ozone climatology of the nineteen seventies deduced from the GASP aircraft measurement program

2007 ◽  
Vol 7 (2) ◽  
pp. 3451-3517 ◽  
Author(s):  
C. Schnadt Poberaj ◽  
J. Staehelin ◽  
D. Brunner ◽  
V. Thouret ◽  
V. Mohnen
Keyword(s):  
United States ◽  
Large Scale ◽  
The United States ◽  
Eastern United States ◽  
Nineteen Seventies ◽  
Large Variability ◽  
Tropical Regions ◽  
Mixing Ratios ◽  
Research Aircraft ◽  
Atmospheric Sampling

Abstract. The knowledge of historical ozone in the upper troposphere/lower stratosphere (UT/LS) region is mostly confined to regular measurements from a number of ozonesonde stations. We present ozone measurements of the Global Atmospheric Sampling Program (GASP) performed from four commercial and one research aircraft during 1975 to 1979. Using GASP data, a UT/LS ozone climatology of 1975–1979 was built. Seasonality and concentrations of GASP UT ozone in the middle, subtropical and tropical regions of the northern hemisphere (NH) are generally in agreement with other published observations, derived from ozonesondes or aircraft campaigns. In regions where both GASP (1970s) and MOZAIC (1990s) data are available, similar ozone concentrations are found and seasonal cycles agree well confirming the reliability of GASP ozone. GASP provides unique large-scale climatological information on UT/LS ozone above the NH Pacific region. Agreement is found with observations from individual ozonesonde sites and aircraft campaigns carried out over this region. Tropical UT ozone is seen to be lower near the dateline than further east, presumably related to uplift of ozone poor air within convection. Over the west coast of the United States, summer UT ozone is higher than over the adjacent Pacific, probably caused by air pollution over southern California in the 1970s. GASP offers an unprecedented opportunity to link to European, Canadian and U.S. American ozonesonde observations of the 1970s. For the quantitative comparison, an altitude offset was applied to the sonde data to account for the slow response time of the sensors. In the LS, the European and Canadian Brewer-Mast (BM) sensors then agree to ±10% with the GASP instruments in all seasons. In the UT, the European BM sondes record similar to slightly less average ozone than GASP, however, with large variability overlaid. Over the eastern United States, systematic positive deviations of the Wallops Island ECC sondes from GASP of +20% are found. The comparisons over Europe and the eastern United States corroborate earlier findings that the early ECC sensors may have measured 10 to 25% more ozone than the BM sensors. Our results further indicate that applying the correction factor to the 1970s BM ozonesondes is necessary to yield reliable ozone mixing ratios in the UT/LS.

Fluvial activity in major river basins of the eastern United States during the Holocene

The Holocene ◽  
2020 ◽  
Vol 30 (9) ◽  
pp. 1279-1295
Author(s):  
Ray Lombardi ◽  
Lisa Davis ◽  
Gary E Stinchcomb ◽  
Samuel E Munoz ◽  
Lance Stewart ◽  
...  
Keyword(s):  
United States ◽  
Large Scale ◽  
Gulf Coast ◽  
Human Impacts ◽  
Climatic Conditions ◽  
Ice Age ◽  
Cyclic Behavior ◽  
Eastern United States ◽  
Site Specific ◽  
The Holocene

In the eastern United States, existing paleo-reconstructions in fluvial environments consist primarily of site-specific investigations of climate and human impacts on riverine processes. This paper presents the first meta-analysis of fluvial reconstructions focused on regional watersheds of the eastern United States, including the Lower Mississippi, Tennessee, South Atlantic–Gulf Coast, Ohio, Mid-Atlantic, and New England regional watersheds. Chronologies of fluvial activity (i.e. alluvial deposition) and stability (i.e. landscape stability) were developed by synthesizing data from existing, published, and site-specific fluvial reconstruction studies conducted across the eastern United States. Overall, regional watersheds show variable patterns of synchronicity across watersheds and did not demonstrate cyclic behavior through the Holocene. During the last millennium, only the Lower Mississippi and Ohio regional watersheds exhibit high rates of fluvial activity active during the ‘Medieval Climate Anomaly’ (650–1050 yr BP), while nearly all other regional watersheds in the eastern United States were active during the ‘Little Ice Age’ (100–500 yr BP). These findings imply that fluvial activity may be more spatially restricted during warmer/drier climatic conditions than during cooler/wetter periods. We find an increase in fluvial activity during the era of Euro-American colonization (400 yr BP to present) in the southeastern United States but not the northeastern United States, implying a heterogeneous response of fluvial systems to human activities in the eastern United States related to climatic, cultural, and/or physiographic variability. These new insights gained from fluvial chronologies in the eastern United States demonstrate the utility of regionally synthesized paleo-records to understand large-scale climate variation effect on rivers.

Rates of retained and discarded catches from demersal fish trawling off the north-eastern United States

1997 ◽  
Vol 48 (3) ◽  
pp. 185 ◽  
Author(s):  
S. J. Kennelly ◽  
S. C. Drew ◽  
C. D. Delano Gagnon
Keyword(s):  
United States ◽  
Large Scale ◽  
Demersal Fish ◽  
Statistical Analyses ◽  
Individual Species ◽  
Eastern United States ◽  
Spatial And Temporal Patterns ◽  
The North ◽  
North Eastern ◽  
Catch Rates

The retained- and discarded-catch rates of fish, crustaceans and molluscs caught by demersal fish trawlers were quantified in a large-scale observer survey of fleets working off the north-eastern United States. The data presented come from catches sampled from 7757 tows on 1010 fishing trips during the four-year period from July 1990 to June 1994 and are summarized as the weights retained and discarded (per hour of trawling) for many of the important commercial and recreational species in the region. Problems with the spatial and temporal design of the programme restricted statistical analyses of the data and prevented summaries across all statistical areas and months. However, separate summaries for individual areas (over all months) and individual months (over all areas) identified several spatial and temporal patterns in retained- and discarded-catch rates for individual species and combinations of species. Noticeable increases and decreases in catch rates during the four-year period provided information on the relative health of certain stocks, and overall discard percentages indicated relative selectivities of the trawling operations sampled.

Identification of large scale climate patterns affecting snow variability in the eastern United States

2008 ◽  
Vol 28 (3) ◽  
pp. 315-328 ◽  
Author(s):  
Jennifer Morin ◽  
Paul Block ◽  
Balaji Rajagopalan ◽  
Martyn Clark
Keyword(s):  
United States ◽  
Large Scale ◽  
Eastern United States ◽  
Climate Patterns

scholarly journals Spatiotemporal Variability of Tropical Cyclone Precipitation Using a High-Resolution, Gridded (0.25° × 0.25°) Dataset for the Eastern United States, 1948–2015

2020 ◽  
Vol 33 (5) ◽  
pp. 1803-1819 ◽  
Author(s):  
Joshua C. Bregy ◽  
Justin T. Maxwell ◽  
Scott M. Robeson ◽  
Jason T. Ortegren ◽  
Peter T. Soulé ◽  
...  
Keyword(s):  
United States ◽  
Tropical Cyclone ◽  
Large Scale ◽  
Southern Oscillation ◽  
Spatiotemporal Variability ◽  
Eastern United States ◽  
Percentage Contribution ◽  
Rain Gauges ◽  
The North ◽  
Climate Interactions

AbstractTropical cyclones (TCs) are an important source of precipitation for much of the eastern United States. However, our understanding of the spatiotemporal variability of tropical cyclone precipitation (TCP) and the connections to large-scale atmospheric circulation is limited by irregularly distributed rain gauges and short records of satellite measurements. To address this, we developed a new gridded (0.25° × 0.25°) publicly available dataset of TCP (1948–2015; Tropical Cyclone Precipitation Dataset, or TCPDat) using TC tracks to identify TCP within an existing gridded precipitation dataset. TCPDat was used to characterize total June–November TCP and percentage contribution to total June–November precipitation. TCP totals and contributions had maxima on the Louisiana, North Carolina, and Texas coasts, substantially decreasing farther inland at rates of approximately 6.2–6.7 mm km−1. Few statistically significant trends were discovered in either TCP totals or percentage contribution. TCP is positively related to an index of the position and strength of the western flank of the North Atlantic subtropical high (NASH), with the strongest correlations concentrated in the southeastern United States. Weaker inverse correlations between TCP and El Niño–Southern Oscillation are seen throughout the study site. Ultimately, spatial variations of TCP are more closely linked to variations in the NASH flank position or strength than to the ENSO index. The TCP dataset developed in this study is an important step in understanding hurricane–climate interactions and the impacts of TCs on communities, water resources, and ecosystems in the eastern United States.

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