Aspen_Population_GIS

This file contains ArcGIS GRID files that represent the predicted distributions of EP, NC, and SC

model_evaluation_and_variables

This zip file contains the outputs from the models for the model evaluation scores, and the relative contributions of each variabl

Detection of Salt Marsh Vegetation Stress and Recovery after the Deepwater Horizon Oil Spill in Barataria Bay, Gulf of Mexico Using AVIRIS Data

<div><p>The British Petroleum Deepwater Horizon Oil Spill in the Gulf of Mexico was the biggest oil spill in US history. To assess the impact of the oil spill on the saltmarsh plant community, we examined Advanced Visible Infrared Imaging Spectrometer (AVIRIS) data flown over Barataria Bay, Louisiana in September 2010 and August 2011. Oil contamination was mapped using oil absorption features in pixel spectra and used to examine impact of oil along the oiled shorelines. Results showed that vegetation stress was restricted to the tidal zone extending 14 m inland from the shoreline in September 2010. Four indexes of plant stress and three indexes of canopy water content all consistently showed that stress was highest in pixels next to the shoreline and decreased with increasing distance from the shoreline. Index values along the oiled shoreline were significantly lower than those along the oil-free shoreline. Regression of index values with respect to distance from oil showed that in 2011, index values were no longer correlated with proximity to oil suggesting that the marsh was on its way to recovery. Change detection between the two dates showed that areas denuded of vegetation after the oil impact experienced varying degrees of re-vegetation in the following year. This recovery was poorest in the first three pixels adjacent to the shoreline. This study illustrates the usefulness of high spatial resolution airborne imaging spectroscopy to map actual locations where oil from the spill reached the shore and then to assess its impacts on the plant community. We demonstrate that post-oiling trends in terms of plant health and mortality could be detected and monitored, including recovery of these saltmarsh meadows one year after the oil spill.</p></div

Index trajectories from shore to inland along oiled and oil-free shoreline.

<p>Box plots of index values for pixels vs. zone from shore (“1” being the first pixel from the shore and “12” being the twelfth) for oiled (red) and oil-free (blue) shoreline for the September 2010 dataset for (a) mNDVI, (b) NDII, (c) Angle at NIR, and (d) Absorption depth of water centered near 980nm. Distributions with non-overlapping notches are significantly different from each other. The notch represents the 95% confidence interval, the box extends from the first to the third quartile and the dashed lines extend to the data point which is 1.5 times the interquartile range.</p

Vegetation indexes used for stress detection due to oil contamination.

<p>Vegetation indexes used for stress detection due to oil contamination.</p

Confusion matrices for September 2010 and August 2011 classifications.

<p>Confusion matrices for classification of September 2010 and August 2011 imagery using user-interpreted data. In September 2010, there were no oil-free non-photosynthetic vegetation (NPV) and oil-free soil pixels and in August 2011, there were no oiled pixels in validation data.</p

NDVI image, classified image and zones used to analyze oil impact.

<p>(a) Gray scale NDVI image of a subset of Barataria Bay, with a close up of an oiled section of the shoreline showing (b) the classified image, (c) the zones as we move away from the shoreline, and (d) the NDVI image showing the low-NDVI band of pixels right next to the oiled shoreline. For comparison, (e) shows the NDVI profile for an oil-free section of the shoreline.</p

Upper Barataria Bay study area.

<p>Shows shoreline reach oil fractions, NDVI validation locations (red x’s), water level measurement site (blue circle).</p

Confusion matrix for oiled vs. oil-free pixels in September 2010.

<p>Confusion matrices for classification of oiled pixels in September 2010 using field data collected by Kokaly et al. <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0078989#pone.0078989-Kokaly1" target="_blank">[5]</a>.</p

Land loss rates over reach oiling categories.

<p>Pre-oiling (2006–2010), post-oiling (2010–2013), post-oiling (2013–2016), and background land loss rates over reach oiling categories.</p