David W. Roberts

Montana State University

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Brooke N. Shadel

Saint Louis University

Robert G. Evans

Royal College of Anaesthetists

Linda H. Geiser

US Forest Service

Denise Jordan-Izaguirre

Agency for Toxic Substances and Disease Registry

Patrick Jantz

Northern Arizona University

S. Clardy

Food and Nutrition Service

Jill A. McMurray

US Forest Service

Dolors Armenteras

Universidad Nacional de Colombia

Andrew J. Hansen

Montana State University

Alyson East

Montana State University

Cooperative Institutions

Montana State University

Swiss Federal Institute for Forest, Snow and Landscape Research

University of Maryland, College Park

Montana Institute on Ecosystems

US Forest Service

ETH Zurich

University of Maryland, Baltimore

United States Department of Agriculture

ORCID

United States Geological Survey

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Background levels of non-ortho-substituted (coplanar) polychlorinated biphenyls in human serum of Missouri residents

Chemosphere (2001)

Brooke N. Shadel Robert G. Evans David W. Roberts S. Clardy Denise Jordan-Izaguirre

Polychlorinated biphenyl

Toxic equivalency factor

Congener

10.1016/s0045-6535(00)00457-4

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Citations (20)

Caledonides of northernmost Norway (Finnmark)

B. A. Sturt David W. Roberts

10.4095/103544

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Citations (6)

Use of a Wetland Index to Evaluate Changes in Riparian Vegetation After Livestock Exclusion¹

JAWRA Journal of the American Water Resources Association (2007)

Marc Coles-Ritchie David W. Roberts Jeffrey L. Kershner Richard C. Henderson

Abstract: A method was developed to characterize ecological integrity of riparian sites based on the abundance of hydric species. This wetland index can be calculated with species data, or with community type data as performed here. Classified riparian community types were used to describe vegetation at 14 livestock exclosures and adjacent grazed areas. Community type wetland index values were generated and used to calculate site wetland index values. It was hypothesized that removal of livestock would result in higher wetland index values because of release from herbivory and decreased physical disturbance of vegetation, streambanks, and soil. The wetland index for exclosures was about 12% higher than grazed sites; differences were statistically significant ( p < 0.01) based on paired t ‐tests. The increase in hydric vegetation after livestock exclusion may have contributed to the greater bank stability ( p = 0.002) and smaller width‐to‐depth ratio ( p = 0.005) in exclosures. Challenges were encountered in using community types to describe and compare site vegetation, which could be avoided with species data collection. The wetland index can be a tool to monitor sites over time, compare sites with similar environments, or compare sites for which environmental differences can be accounted.

Hydric soil

Vegetation types

10.1111/j.1752-1688.2007.00058.x

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Citations (29)

Measuring Understory Fire Effects from Space: Canopy Change in Response to Tropical Understory Fire and What This Means for Applications of GEDI to Tropical Forest Fire

Remote Sensing (2023)

Alyson East Andrew J. Hansen Dolors Armenteras Patrick Jantz David W. Roberts

The ability to measure the ecological effects of understory fire in the Amazon on a landscape scale remains a frontier in remote sensing. The Global Ecosystem Dynamics Investigation’s (GEDI) LiDAR data have been widely suggested as a critical new tool in this field. In this paper, we use the GEDI Simulator to quantify the nuanced effects of understory fire in the Amazon, and assess the ability of on-orbit GEDI data to do the same. While numerous ecological studies have used simulated GEDI data, on-orbit constraint may limit ecological inference. This is the first study that we are aware of that directly compares methods using simulated and on-orbit GEDI data. Simulated GEDI data showed that fire effects varied nonlinearly through the canopy and then moved upward with time since burn. Given that fire effects peaked in the mid-canopy and were often on the scale of 2 to 3 m in height difference, it is unlikely that on-orbit GEDI data will have the sensitivity to detect these same changes.

Understory

10.3390/rs15030696

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Citations (12)

Perennial crop legacy effects on nematode community structure in semi-arid wheat systems

Applied Soil Ecology (2019)

Andy Burkhardt Shabeg S. Briar John M. Martin Patrick M. Carr Jennifer Lachowiec

Crop Rotation

Summer fallow

Soil Food Web

Soil Quality

10.1016/j.apsoil.2018.12.020

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Citations (6)

Aquatic toxicity of ethoxylated and propoxylated alcohols to Daphnia magna

Environmental Toxicology and Chemistry (2006)

Jayne Roberts Stuart Marshall David W. Roberts

Ethoxylated alcohols, which are used as nonionic surfactants, are known to act as general narcotics in acute aquatic toxicity; that is, they behave in the same way as nonsurfactant unreactive organic chemicals. The toxicity of such chemicals is well predicted by quantitative structure-activity relationships based solely on the logarithm of the octanol/water partition coefficient (log P), which can be calculated from structure. In the present study, we have shown, using experimental results, that a similar approach can be used to determine the toxicity of ethoxylate/propoxylate alcohols (i.e., containing propoxy [PO] and ethoxy [EO] units). Our calculations indicate that use of the Roberts position-dependent branching factor in calculating the PO group contribution is more appropriate than the Leo and Hansch branch factor. The resulting log P value for a PO group is 0.01; that is, the overall contribution to the final log P value is close to zero. On this basis, it is predicted that nonionic surfactants containing both EO and PO groups should have the same molar toxicity as surfactants based on the same parent alcohol and with the same number of EO groups but with no PO groups. This prediction has been confirmed in Daphnia acute toxicity tests. Furthermore, both EO/PO and EO-only nonionics are found to fit the same linear relationship between log P and toxicity.

Daphnia magna

Aquatic toxicology

10.1897/07-023r.1

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Citations (13)

Epiphytic lichen indication of nitrogen deposition and climate in the northern rocky mountains, USA

Ecological Indicators (2014)

Jill A. McMurray David W. Roberts Linda H. Geiser

Epiphyte

Deposition

10.1016/j.ecolind.2014.10.015

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