Hemlock Inventory / Analysis Data?


We’ve met at SAMAB and I remembered the FIA office is here in Knoxville.

I have a question and thought you’d be a likely person to ask – I’m wondering if you happen to have access to or be aware of a high-resolution dataset depicting hemlock point locations or polygons in Great Smoky Mountains National Park? I realize hemlocks are the subject of scrutiny given their decline due to the HWA.

I’m interested in using high accuracy data models of hemlock distribution to test the accuracy of a statistically derived distribution model that pairs point occurrence records for hemlock collected by volunteers with constraining environmental variables to explore the maximum distribution subject to the environmental constraints (maximum entropy).

Because the point location data I have is collected by humans on the ground, there’s a risk for bias in the records (e.g., we may have an abundance of "trees that grow near trails").

I was thinking I could use a hemlock declines dataset from the Forest Service to come up with an objective way of establishing the actual distribution of Hemlocks (or rather, the "preferred" distribution, pre-adelgid).

The highest resolution dataset the Park Service has online delineating hemlock distribution seems to be polygons created by photo interpreters working with 1:12,000 scale color infrared images.

If the kind of dataset I’m hoping for does not already exist, I’m thinking to use OpenForis Collect Earth to visually examine the 15 x 15 m satellite imagery in Google Earth to record the location of denuded hemlock skeletons in the Park.

I don’t know what the exact mortality of hemlock in the Park is, but it seems to be pretty comprehensive. I’m hoping point coordinates for hemlock skeletons will inform a "ground truthed" distribution of hemlocks in comparison to the statistical model’s predicted distribution.

At any rate, Paul Super with the Park Service suggested I should inquire with the Forest Service first.

Thanks for any thoughts on this,


Tanner M. Jessel
Information Technology Specialist
Center for Renewable Carbon


The University of Tennessee
Institute of Agriculture
Center for Renewable Carbon
Mail: 2506 Jacob Drive
865-946-1162 (o)
865-946-1109 (f)


About Tanner Jessel

I am a recent M.S. in Information Science graduate from the University of Tennessee School of Information Science. I was formerly a graduate research assistant funded by DataONE (Data Observation Network for Earth). Prior, I worked for four years as a content lead and biodiversity scientist with the U.S. Geological Survey's Biodiversity Informatics Program. Building on my work experience in biodiversity and environmental informatics, my work with DataONE focused on exploring the nature of scientific collaborations necessary for scientific inquiry. I also conducted research concerning user experience and usability, and assisted in development of member nodes with an emphasis on spatial data and infrastructure. I assisted with research designed to understand sociocultural issues within collaborative research communities. Through August 1, 2014, I was based at the Center for Information and Communication Studies at the University of Tennessee School of Information Science in Knoxville, Tennessee.

Posted on December 16, 2014, in Uncategorized. Bookmark the permalink. Leave a comment.

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