Physical Sciences and Mathematics | Open Access Articles

Stratigraphic Control Of Landscape Response To Base-Level Fall, Young Womans Creek, Pennsylvania, Usa, Roman A. Dibiase, Alison R. Denn, Paul R. Bierman, Eric Kirby, Nicole West, Alan J. Hidy

College of Arts and Sciences Faculty Publications

Landscapes are thought to respond to changes in relative base level through the upstream propagation of a boundary that delineates relict from adjusting topography. However, spatially-variable rock strength can influence the topographic expression of such transient landscapes, especially in layered rocks, where strength variations can mask topographic signals expected due to changes in climate or tectonics. Here, we analyze the landscape response to base-level fall in Young Womans Creek, a 220 km2 catchment on the Appalachian Plateau, USA underlain by gently folded Paleozoic sedimentary rocks. We measured in situ 10Be concentrations in stream sands from 17 nested watersheds, and used …

Go to article

Similarity Of Introduced Plant Species To Native Ones Facilitates Naturalization, But Differences Enhance Invasion Success, Jan Divíšek, Milan Chytrý, Brian Beckage, Nicholas J. Gotelli, Zdeňka Lososová, Petr Pyšek, David M. Richardson, Jane Molofsky

College of Arts and Sciences Faculty Publications

The search for traits associated with plant invasiveness has yielded contradictory results, in part because most previous studies have failed to recognize that different traits are important at different stages along the introduction–naturalization–invasion continuum. Here we show that across six different habitat types in temperate Central Europe, naturalized non-invasive species are functionally similar to native species occurring in the same habitat type, but invasive species are different as they occupy the edge of the plant functional trait space represented in each habitat. This pattern was driven mainly by the greater average height of invasive species. These results suggest that the …

Go to article

Socioeconomic And Environmental Proxies For Comparing Freshwater Ecosystem Service Threats Across International Sites: A Diagnostic Approach, Thomas C. Harmon, Robyn L. Smyth, Sudeep Chandra, Daniel Conde, Ramesh Dhungel, Jaime Escobar, Natalia Hoyos

College of Arts and Sciences Faculty Publications

In this work, we develop and test proxy-based diagnostic tools for comparing freshwater ecosystem services (FWES) risks across an international array of freshwater ecosystems. FWES threats are increasing rapidly under pressure from population, climate change, pollution, land use change, and other factors. We identified spatially explicit FWES threats estimates (referred to as threat benchmarks) and extracted watershed-specific values for an array of aquatic ecosystems in the Western Hemisphere (Ramsar sites). We compared these benchmark values to values extracted for sites associated with an international FWES threat investigation. The resulting benchmark threats appeared to provide a meaningful context for the diagnostic …

Go to article

Disentangling Biotic Interactions, Environmental Filters, And Dispersal Limitation As Drivers Of Species Co-Occurrence, Manuela D'Amen, Heidi K. Mod, Nicholas J. Gotelli, Antoine Guisan

College of Arts and Sciences Faculty Publications

A key focus in ecology is to search for community assembly rules. Here we compare two community modelling frameworks that integrate a combination of environmental and spatial data to identify positive and negative species associations from presence–absence matrices, and incorporate an additional comparison using joint species distribution models (JSDM). The frameworks use a dichotomous logic tree that distinguishes dispersal limitation, environmental requirements, and interspecific interactions as causes of segregated or aggregated species pairs. The first framework is based on a classical null model analysis complemented by tests of spatial arrangement and environmental characteristics of the sites occupied by the members …

Go to article

A New Machine-Learning Approach For Classifying Hysteresis In Suspended-Sediment Discharge Relationships Using High-Frequency Monitoring Data, Scott D. Hamshaw, Mandar M. Dewoolkar, Andrew W. Schroth, Beverley C. Wemple, Donna M. Rizzo

College of Arts and Sciences Faculty Publications

Studying the hysteretic relationships embedded in high-frequency suspended-sediment concentration and river discharge data over 600+ storm events provides insight into the drivers and sources of riverine sediment during storm events. However, the literature to date remains limited to a simple visual classification system (linear, clockwise, counter-clockwise, and figure-eight patterns) or the collapse of hysteresis patterns to an index. This study leverages 3 years of suspended-sediment and discharge data to show proof-of-concept for automating the classification and assessment of event sediment dynamics using machine learning. Across all catchment sites, 600+ storm events were captured and classified into 14 hysteresis patterns. Event …

Go to article

Modeling The Impacts Of Changing Climatic Extremes On Streamflow And Sediment Yield In A Northeastern Us Watershed, J. Stryker, B. Wemple, A. Bomblies

College of Arts and Sciences Faculty Publications

Study region: We investigate the impacts of local temperature and precipitation trends on discharge and sediment loading by applying the model to a watershed in the northeastern US, where trends in increasing precipitation exceed those of other regions in North America. Study focus: In this study we simulate the response of watershed sediment loading to changing frequencies and magnitudes of extreme precipitation events using a coupled model that explicitly simulates streambank erosion and failure within a distributed watershed model. To drive the model, we use meteorological inputs from general circulation models (GCMs) as well as from a statistical weather generator …

Go to article

Functional Traits And Environmental Characteristics Drive The Degree Of Competitive Intransitivity In European Saltmarsh Plant Communities, Werner Ulrich, Yasuhiro Kubota, Agnieszka Piernik, Nicholas J. Gotelli

College of Arts and Sciences Faculty Publications

Competitive intransitivity, the existence of loops in competitive hierarchies, is one mechanism that can promote the local coexistence of competitors and maintain high local species diversity, although its prevalence and importance remain largely unknown. A full understanding of local community assembly needs knowledge of how transitive and intransitive competitive interactions are linked to species functional traits and the strength of biotic and abiotic filters. We apply a recently developed statistical tool to quantitative data on central European inland saltmarsh plant communities to infer causal relationships between soil characteristics, species occurrences and functional traits, and we estimated coefficients of competition. We …

Go to article

Cosmogenic Nuclides Indicate That Boulder Fields Are Dynamic, Ancient, Multigenerational Features, Alison R. Denn, Paul R. Bierman, Susan R.H. Zimmerman, Marc W. Caffee, Lee B. Corbett, Eric Kirby

College of Arts and Sciences Faculty Publications

Boulder fields are found throughout the world; yet, the history of these features, as well as the processes that form them, remain poorly understood. In high and mid-latitudes, boulder fields are thought to form and be active during glacial periods; however, few quantitative data support this assertion. Here, we use in situ cosmogenic 10Be and 26Al to quantify the near-surface history of 52 samples in and around the largest boulder field in North America, Hickory Run, in central Pennsylvania, USA. Boulder surface 10Be concentrations (n = 43) increase downslope, indicate minimum near-surface histories of 70-600 k.y., and are not correlated …

Go to article

Effects Of Different Soil Media, Vegetation, And Hydrologic Treatments On Nutrient And Sediment Removal In Roadside Bioretention Systems, Paliza Shrestha, Stephanie E. Hurley, Beverley C. Wemple

College of Arts and Sciences Faculty Publications

Water quality performance of eight roadside bioretention cells in their third and fourth years of implementation were evaluated in Burlington, Vermont. Bioretention cells received varying treatments: (1) vegetation with high-diversity (7 species) and low-diversity plant mix (2 species); (2) proprietary SorbtiveMedia™ (SM) containing iron and aluminum oxide granules to enhance sorption capacity for phosphorus; and (3) enhanced rainfall and runoff (RR) to certain cells (including one with SM treatment) at three levels (15%, 20%, 60% more than their control counterparts), mimicking anticipated precipitation increases associated with climate change. A total of 121 storms across all cells were evaluated in 2015 …

Go to article

Econullnetr: An R Package Using Null Models To Analyse The Structure Of Ecological Networks And Identify Resource Selection, Ian P. Vaughan, Nicholas J. Gotelli, Jane Memmott, Caitlin E. Pearson, Guy Woodward, William O.C. Symondson

College of Arts and Sciences Faculty Publications

Network analysis is increasingly widespread in ecology, with frequent questions asking which nodes (typically species) interact with one another and how strong are the interactions. Null models are a way of addressing these questions, helping to distinguish patterns driven by neutral mechanisms or sampling effects (e.g. relative abundance of different taxa, sampling completeness) from deterministic biological mechanisms (e.g. resource selection and avoidance), but few “off the shelf” tools are available. We present econullnetr, an r package combining null modelling and plotting functions for networks, with data-export tools to facilitate its use alongside existing network analysis packages. It models resource choices …

Go to article

Bi-Dimensional Null Model Analysis Of Presence-Absence Binary Matrices, Giovanni Strona, Werner Ulrich, Nicholas J. Gotelli

College of Arts and Sciences Faculty Publications

Ecology, published by Wiley Periodicals, Inc., on behalf of the Ecological Society of America. Comparing the structure of presence/absence (i.e., binary) matrices with those of randomized counterparts is a common practice in ecology. However, differences in the randomization procedures (null models) can affect the results of the comparisons, leading matrix structural patterns to appear either “random” or not. Subjectivity in the choice of one particular null model over another makes it often advisable to compare the results obtained using several different approaches. Yet, available algorithms to randomize binary matrices differ substantially in respect to the constraints they impose on the …

Go to article

Physical Sciences and Mathematics Commons^™

Full-Text Articles in Physical Sciences and Mathematics

Stratigraphic Control Of Landscape Response To Base-Level Fall, Young Womans Creek, Pennsylvania, Usa, Roman A. Dibiase, Alison R. Denn, Paul R. Bierman, Eric Kirby, Nicole West, Alan J. Hidy

College of Arts and Sciences Faculty Publications

Similarity Of Introduced Plant Species To Native Ones Facilitates Naturalization, But Differences Enhance Invasion Success, Jan Divíšek, Milan Chytrý, Brian Beckage, Nicholas J. Gotelli, Zdeňka Lososová, Petr Pyšek, David M. Richardson, Jane Molofsky

College of Arts and Sciences Faculty Publications

Socioeconomic And Environmental Proxies For Comparing Freshwater Ecosystem Service Threats Across International Sites: A Diagnostic Approach, Thomas C. Harmon, Robyn L. Smyth, Sudeep Chandra, Daniel Conde, Ramesh Dhungel, Jaime Escobar, Natalia Hoyos

College of Arts and Sciences Faculty Publications

Disentangling Biotic Interactions, Environmental Filters, And Dispersal Limitation As Drivers Of Species Co-Occurrence, Manuela D'Amen, Heidi K. Mod, Nicholas J. Gotelli, Antoine Guisan

College of Arts and Sciences Faculty Publications

A New Machine-Learning Approach For Classifying Hysteresis In Suspended-Sediment Discharge Relationships Using High-Frequency Monitoring Data, Scott D. Hamshaw, Mandar M. Dewoolkar, Andrew W. Schroth, Beverley C. Wemple, Donna M. Rizzo

College of Arts and Sciences Faculty Publications

Modeling The Impacts Of Changing Climatic Extremes On Streamflow And Sediment Yield In A Northeastern Us Watershed, J. Stryker, B. Wemple, A. Bomblies

College of Arts and Sciences Faculty Publications

Functional Traits And Environmental Characteristics Drive The Degree Of Competitive Intransitivity In European Saltmarsh Plant Communities, Werner Ulrich, Yasuhiro Kubota, Agnieszka Piernik, Nicholas J. Gotelli

College of Arts and Sciences Faculty Publications

Cosmogenic Nuclides Indicate That Boulder Fields Are Dynamic, Ancient, Multigenerational Features, Alison R. Denn, Paul R. Bierman, Susan R.H. Zimmerman, Marc W. Caffee, Lee B. Corbett, Eric Kirby

College of Arts and Sciences Faculty Publications

Effects Of Different Soil Media, Vegetation, And Hydrologic Treatments On Nutrient And Sediment Removal In Roadside Bioretention Systems, Paliza Shrestha, Stephanie E. Hurley, Beverley C. Wemple

College of Arts and Sciences Faculty Publications

Econullnetr: An R Package Using Null Models To Analyse The Structure Of Ecological Networks And Identify Resource Selection, Ian P. Vaughan, Nicholas J. Gotelli, Jane Memmott, Caitlin E. Pearson, Guy Woodward, William O.C. Symondson

College of Arts and Sciences Faculty Publications

Bi-Dimensional Null Model Analysis Of Presence-Absence Binary Matrices, Giovanni Strona, Werner Ulrich, Nicholas J. Gotelli

College of Arts and Sciences Faculty Publications