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.

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 A simple conceptual model to interpret the 100 000 years dynamics of paleo-climate records

2010 ◽  
Vol 17 (5) ◽  
pp. 585-592 ◽  
Author(s):  
C. S. Quiroga Lombard ◽  
P. Balenzuela ◽  
H. Braun ◽  
D. R. Chialvo
Keyword(s):  
Large Scale ◽  
Power Spectra ◽  
Greenland Ice Sheet ◽  
Ice Age ◽  
Solar Cycles ◽  
The Holocene ◽  
De Vries ◽  
Last Ice Age ◽  
Paleoclimate Records ◽  
Dominant Frequencies

Abstract. Spectral analyses performed on records of cosmogenic nuclides reveal a group of dominant spectral components during the Holocene period. Only a few of them are related to known solar cycles, i.e., the De Vries/Suess, Gleissberg and Hallstatt cycles. The origin of the others remains uncertain. On the other hand, time series of North Atlantic atmospheric/sea surface temperatures during the last ice age display the existence of repeated large-scale warming events, called Dansgaard-Oeschger (DO) events, spaced around multiples of 1470 years. The De Vries/Suess and Gleissberg cycles with periods close to 1470/7 (~210) and 1470/17 (~86.5) years have been proposed to explain these observations. In this work we found that a conceptual bistable model forced with the De Vries/Suess and Gleissberg cycles plus noise displays a group of dominant frequencies similar to those obtained in the Fourier spectra from paleo-climate during the Holocene. Moreover, we show that simply changing the noise amplitude in the model we obtain similar power spectra to those corresponding to GISP2 δ18O (Greenland Ice Sheet Project 2) during the last ice age. These results give a general dynamical framework which allows us to interpret the main characteristic of paleoclimate records from the last 100 000 years.

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.

Quaternary North American Vegetational History: 1.6 Ma to the Present

1999 ◽  
Author(s):  
Alan Graham
Keyword(s):  
United States ◽  
Mississippi River ◽  
Ice Age ◽  
Quaternary Period ◽  
Radiocarbon Dates ◽  
The Holocene ◽  
Oxygen Isotope Stage ◽  
Continental Scale ◽  
Northern Latitudes ◽  
The University

The Quaternary Period encompasses the Pleistocene and the Holocene or Recent Epochs. The date used for the beginning of the Pleistocene depends upon which globally recognizable event is selected as representing a significant break with the preceding Pliocene Epoch. Candidates include the Gauss-Matuyama magnetopolarity boundary (~2.8 Ma; see Quaternary International, 1997); the initiation of widespread permafrost, a frigid Arctic Ocean, and rapid glaciation in the high northern latitudes (~2.4 Ma; Shackleton and Opdyke, 1977; Shackleton et al., 1984); or the African Olduvai paleomagnetic event between 1.87 and 1.67 Ma. The transition from hothouse to icehouse conditions was gradual, but the Pleistocene is typified at Vrica, Italy, as beginning at ~1.67 Ma (Aguirre and Pasini, 1985; Richmond and Fullerton, 1986; oxygen isotope stage 62), and that is the date used here. In the conterminous United States the Elk Creek till of Nebraska is 2.14 m.y. in age (Hallberg, 1986), and the onset of the full ice age is represented by the onset of repeated glaciations at ~850 Kya when glaciers extended down the Mississippi River Valley. Subsequently, glacial-interglacial conditions fluctuated until the latest retreat at ~11 Kya that began the Holocene or Recent Epoch. The chronology of ice age events began with the publication of Louis Agassiz’s (1840) Etudes surles Glaciers. In the absence of evidence to the contrary, a single glacial advance was envisioned as blanketing the high latitudes. In the 1940s Willard E Libby at the University of Chicago perfected the technique of radiocarbon dating, and Flint and Rubin (1955) applied this methodology of “isotopic clocks” to establishing the absolute chronology of drift deposits from the eastern and midwestern United States. Their radiocarbon dates showed evidence of two or more times of continental-scale glaciations; older organic material was “radiocarbon inert” and beyond the ~40-Ky range of the technique. A standard chronology eventually became established for North America that included four major glacial stages (Nebraskan, oldest; Kansan; Illinoian; and Wisconsin) separated by four interglacials (Aftonian, oldest; Yarmouth, Sangamon, and the present Holocene).

scholarly journals Millennial-scale faunal record reveals differential resilience of European large mammals to human impacts across the Holocene

2016 ◽  
Vol 283 (1827) ◽  
pp. 20152152 ◽  
Author(s):  
Jennifer J. Crees ◽  
Chris Carbone ◽  
Robert S. Sommer ◽  
Norbert Benecke ◽  
Samuel T. Turvey
Keyword(s):  
Large Scale ◽  
Temporal Dynamics ◽  
Human Impacts ◽  
Biodiversity Loss ◽  
Mammal Species ◽  
The Holocene ◽  
Range Change ◽  
Spatio Temporal ◽  
Patterns And Processes ◽  
Species Specific

The use of short-term indicators for understanding patterns and processes of biodiversity loss can mask longer-term faunal responses to human pressures. We use an extensive database of approximately 18 700 mammalian zooarchaeological records for the last 11 700 years across Europe to reconstruct spatio-temporal dynamics of Holocene range change for 15 large-bodied mammal species. European mammals experienced protracted, non-congruent range losses, with significant declines starting in some species approximately 3000 years ago and continuing to the present, and with the timing, duration and magnitude of declines varying individually between species. Some European mammals became globally extinct during the Holocene, whereas others experienced limited or no significant range change. These findings demonstrate the relatively early onset of prehistoric human impacts on postglacial biodiversity, and mirror species-specific patterns of mammalian extinction during the Late Pleistocene. Herbivores experienced significantly greater declines than carnivores, revealing an important historical extinction filter that informs our understanding of relative resilience and vulnerability to human pressures for different taxa. We highlight the importance of large-scale, long-term datasets for understanding complex protracted extinction processes, although the dynamic pattern of progressive faunal depletion of European mammal assemblages across the Holocene challenges easy identification of ‘static’ past baselines to inform current-day environmental management and restoration.

scholarly journals Virulence of Puccinia triticina on Wheat in the United States in 1999

Plant Disease ◽  
2002 ◽  
Vol 86 (1) ◽  
pp. 15-19 ◽  
Author(s):  
D. L. Long ◽  
K. J. Leonard ◽  
M. E. Hughes
Keyword(s):  
United States ◽  
Great Plains ◽  
Gulf Coast ◽  
Puccinia Triticina ◽  
Leaf Rust Resistance ◽  
Distribution Patterns ◽  
The United States ◽  
Eastern United States ◽  
Ohio Valley ◽  
Central United States

Isolates of Puccinia triticina were obtained from wheat leaf collections made by cooperators throughout the United States and from surveys of wheat fields and nurseries in the Great Plains, Ohio Valley, and Gulf Coast states in 1999. Pathogenic races were determined from virulence/avirulence phenotypes on 14 host lines that are near-isogenic for leaf rust resistance. We found 58 races among 1,180 isolates in 1999. As in previous surveys, regional race distribution patterns showed that the central United States is a single epidemiological unit distinct from the eastern United States. The distinctive racial composition of collections from the Southeast, Northeast, and Ohio Valley indicates that populations of P. triticina in those areas are not closely connected, suggesting epidemics originate from localized overwintering sources.

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.

scholarly journals Assessing the risks to United States and Canadian mammals caused by climate change using a trait-mediated model

2019 ◽  
Author(s):  
Christy M McCain
Keyword(s):  
Climate Change ◽  
United States ◽  
Large Scale ◽  
Human Impacts ◽  
Mammalian Species ◽  
Species Traits ◽  
The United States ◽  
Mammal Species ◽  
Climate Change Risk ◽  
Very High

Abstract A set of 182 populations of 76 mammal species in the United States and Canada, examined in natural conditions with minimized disturbances or management effects, shows that responses to climate change include negative responses, such as elevational range contractions, upward shifts and decreases in abundance, positive responses, such as range expansions, and no detectable responses. Responses vary among and within mammal species but many are correlated with species traits, particularly the responses linked to high extinction risks (= climate change risk: decreases in population sizes, range contractions, local extirpations). The traits showing the strongest links to differential responses to climate change are 1) body size—large mammals respond more often and most negatively to climate change, 2) activity times—few mammals with flexible active times respond to climate change, and 3) spatial distribution—high-latitude and high-elevation mammals responded more often to climate change. Using these traits and two approaches to trait weighting, I modeled the relative climate change risk for all 328 terrestrial, nonvolant mammal species in the United States and Canada across 10 levels of risk (low = 1–2, moderate = 3–4, moderate-high = 5–6, high = 7–8, very high = 9–10). The models predicted that 15% of these mammalian species are in the high- and very high-risk categories, including species from most orders. Many mammal populations and species listed as of conservation concern due to other human impacts by national or international agencies are also predicted by my models to be in the higher categories of climate change risk. My intention for these models is to clarify for managers and researchers which, where, and how mammals are responding to climate change relatively independent of other anthropogenic stressors (e.g., large-scale habitat change, overhunting) and to provide a preliminary assessment of species most in need of careful monitoring for climate change impacts.

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.

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