Staff Directory

Aziz Ebrahimi

Aziz Ebrahimi

Visiting Scholar

Aziz investigates the level of pollen flow and parentage analysis in 1000 samples of F1 populations in black walnut with molecular markers. He also studies modeling of pollen Flow by a Bayesian Approach, quantifying wind-dispersed chestnut blight spores with qPCR, evaluating of cold hardy gene in different walnuts species using DNA sequencing data, and development and preliminary evaluation of SNP array in walnut species.

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Lorenzo Cotrozzi

Post-doctoral Research Associate

Dr. Cotrozzi’s research interests are plant responses to simultaneous biotic and abiotic stress and vegetation spectroscopy.

Lenny D. Farlee

Lenny D. Farlee

Sustaining Hardwood Extension Specialist

Lenny is an extension forester with the HTIRC. He provides programs and publications in a variety of media directed toward improving the regeneration and sustainable management of high quality hardwood trees and forests in the Central Hardwood Region. Learn More

Janis L. Gosewehr

Janis L. Gosewehr

Administrative Assistant

Janis provides administrative support to the HTIRC. Learn More

Nathanial C. Hilliard

Nathanial (Nathan) C. Hilliard

Laboratory Manager

Nathan is the lab manager for Forest Ecology, Soils and Silviculture Lab, the Molecular Tree Physiology Lab and the Wright Research Center Lab. Learn More

Elizabeth “Liz” A. Jackson

Elizabeth “Liz” A. Jackson

Manager Walnut Council/IFWOA and Engagement Specialist for HTIRC

Liz is the Engagement Specialist for HTIRC, Executive Director of the Indiana Forestry & Woodland Owners Association, and the Executive Director of the National Walnut Council. Learn More

James “Jim” R. McKenna

James “Jim” R. McKenna

USDA Forest Service, Operational Tree Breeder or

Jim works as part of a team of scientists, professors, and students in the Department of Forestry and Natural Resources, along with other researchers at Purdue, the U.S. Forest Service. Learn More

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Patrick O’Neil

Genomics Laboratory Manager

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Lydia Utley

Data Analyst

Lydia works on data analysis for the Center. Learn More


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James “Jim” C. Warren

USDA Forest Service, Biological Scientist/Operational Tree Breeder or

Prior to coming to the HTIRC, Jim assisted in running the daily operations of the Minnesota Tree Improvement Cooperative at the University of Minnesota’s Cloquet Forestry Center for 17 years.  His primary duties entailed designing, implementing, and measuring field trials, assisting with orchard management, conducting tree breeding and grafting, and collecting data. Learn More