Ph.D. - Spatial Risk Assessment of Biological Invasions

August 9, 2016

A Ph.D. position at the University of Nebraska is available in the labs of Dirac Twidwell (the Applied Complex Adaptive Systems Lab) and Craig Allen (Nebraska Cooperative Fish and Wildlife Research Unit). The student will be working as part of an interdisciplinary research team that is leading initiatives that bring together experts from academia, natural resource agencies, NGOs, and private citizens.

The focus of this project is to develop spatial risk assessments that characterize the vulnerability of Nebraska’s imperiled grasslands to woody plant invasions. Woody plant invasions are now recognized widely as a leading reason for the decline of grassland-dependent ecosystem services in the Great Plains. Addressing this challenge requires an intensive programmatic effort that focuses on juniper invasions as a complex social-ecological problem – and where interactions among biophysical, social, and cultural processes dictate system dynamics and outcomes of management interventions. We are assembling a team of researchers, with stakeholder involvement, to determine the landscape and population impacts woody plant invasions in grasslands. Further, the increasing threat of woody invasions, especially by Juniperus species, is a direct result of contemporary changes in land management and the loss of fire as a broad-scale structuring process in Great Plains grasslands. Because of positive reinforcement between invading woody vegetation and structuring processes such as fire, a regime shift from grassland to woody plant dominance is difficult to reverse. Therefore, active management of landscapes in transition is a valued intervention, but great uncertainty exists regarding aggregate landscape impacts of woody invasions and the relative success of the interventions designed to reverse them. Basic reservations regarding fire and its use are at the forefront of this issue, demonstrating that novel and potentially transformative approaches are needed. The development of a spatially explicit risk assessment model will advance current approaches meant to (i) prevent the spread of woody plants into grasslands, and (ii) prioritize restoration in grasslands that have undergone a regime shift to woody plant dominance. The accepted applicant will be trained in spatial risk assessment modeling while having considerable flexibility to advance our current team’s models.


The successful candidate will be highly motivated, passionate about scientific inquiry, possess excellent writing and communication skills, and publish research in refereed scientific journals. Applicants should possess an M.S. in a relevant discipline. Excellent GIS skills are desired. Familiarity with spatial modeling, GIS, and other quantitative statistical or mathematical techniques are also preferred.

Contact and application information:

Students interested in this position should send a statement of interest with research qualifications and career goals, GPA and GRE scores, your most recent transcript (unofficial is fine) and a CV that includes contact information for three references (email preferred). Please send applications to Dirac Twidwell ( or Craig Allen ( Funding is available to start between now and January 2017. Full funding is available for 4 years. The stipend rate for 2017 is $25,980. Full tuition is waived and graduate student health benefits are provided at a reduced rate. Review of applications will begin August 26 and continue until a qualified candidate is identified.