Research

Research Interests and Experience

Broadly, I consider myself a disturbance ecologist. Most of my research addresses questions in forest health, forest ecology, invasion ecology, biocontrol, fire ecology, and silviculture. I conduct both basic and applied research utilizing methods that range from field observations and experimentation to synthesis and analysis of data acquired from the literature or long-term ecological datasets. Below, you will find more information on my broad research interests, as well as my past and current research projects.

“The important thing is not to stop questioning. Curiosity has its own reason for existing.” - Albert Einstein

General Research Interests

Patch of eastern white pine seedlings in White Sulphur Springs, WV

Forest Ecology

In an effort to better understand the ecological processes that occur within forested ecosystems, I am interested in studying everything from the function and composition of different tree species in forest stands, to the role of mycorrhizal fungi in improving tree tolerance to stress, and interactions of disturbance and climate on species distributions.

Matsucoccus macrocicatrices nestled in the branch crotch of an eastern white pine seedling

Forest Entomology

From ground-dwelling ants and crickets, to sap-feeding scale insects and wood-boring beetles, forest insects play an important role in the functions of our forests. Although I focus on insects that occupy trees, I am also interested in insects that are predators, parasitoids, and decomposers in forest ecosystems.

Caliciopsis pinea ascocarps and canker on an eastern white pine seedling

Forest Pathology & Mycology

The signs and symptoms of pathogens can frequently be seen in forests throughout North America. I am interested in how these pathogens work with predisposing, inciting, and other contributing factors to affect the health of trees. I am also interested in the role that decomposing and mycorrhizal fungi have in ecological processes.

Current Research

As a postdoc through Colorado State University, I am collaborating with the USGS Powell Center and National Urban and Community Forestry Advisory Council (NUCFAC) "High-impact insect invasions" working group (HIIWG) to predict the next high-impact insect invaders in rural and urban forests of North America. We have already modeled the drivers of conifer specialists, and found that there is a "sweet spot" when native and novel coniferous hosts have an evolutionary history that is close enough that insect pests can identify and feed on the novel host, but the novel host is far enough removed from the native host that it lacks the defenses necessary to combat the insect. Host evolutionary history can be used to predict whether a conifer specialist that invades in North America is likely going to be high-impact or not. We are currently modeling the woody angiosperm specialists and generalists, and plan on incorporating our models into i-Tree so they can be utilized by professionals in federal, state, local, and/or academic agencies and organizations.

Key Collaborators (HIIWG): Ruth Hufbauer (Colorado State University), Angela Mech (University of Maine), Craig Allen (University of Nebraska), Carissa Aoki (Bates College), Matt Ayres (Dartmouth College), Kamal Gandhi (University of Georgia), Nathan Havill (USDA Forest Service), Dan Herms (Davey Tree), Sandy Liebhold (USDA Forest Service), Scott Maco (Davey Tree), Travis Marsico (Arkansas State University), Ken Raffa (University of Wisconsin), Kathryn Thomas (USGS Southwest Biological Science Center), Patrick Tobin (University of Washington), and Dan Uden (University of Nebraska)

Past Research

As a doctoral student at Arkansas State University, my research focused on linking invasion ecology and biological control to elucidate mechanisms of invasion. Understanding the mechanisms behind successful establishment and impact of non-native insects is vital for preventing and mitigating invasion. Classical biocontrol agents, which share characteristics with non-native species, are an underutilized resource for studying mechanisms of species invasion. I modeled data from three existing biocontrol agent databases, supplemented by refereed literature, to determine which factors drive the establishment and impact of biocontrol agents (manuscript in prep). I also:

Linked accidentally introduced non-native insects and biocontrol agents through discussion of antagonist (i.e., natural enemy) hypotheses and created a unifying framework to simplify the relatedness among the hypotheses,
Worked with the Powell Center HIIWG to evaluate inter-rater agreement among experts assessing the impacts of non-native insect species,
Assessed communication between invasion ecologists and biological control professionals using scientometrics, and
Developed a policy review to assess invasive species policies and provide considerations for detecting and managing potentially high-impact, non-native insects and plants in North America (manuscript in prep)

Key Collaborators: Travis Marsico (Arkansas State University), Rima Lucardi (USDA Forest Service), USGS Powell Center HIIWG (see above)

Top figure from Schulz et al. 2019. BioScience 69(9): 711-724.
Bottom figure from Schulz et al. 2020. NeoBiota 55: 61-83.

As a Master's student at the University of Georgia, I studied abiotic and biotic factors contributing to eastern white pine dieback in the southern Appalachian Mountains. I found that a scale insect, Matsucoccus macrocicatrices, and a fungal pathogen, Caliciopsis pinea, were often found on dying trees, and tree dieback was most prominent on sites with cooler temperatures, small diameter trees, high tree density, and/or presence of C. pinea. In EWP seedlings, I found that the scale insect and cankers were correlated with seedling dieback. The scale insect was most prevalent in C. pinea cankers, which was the only fungal species that formed girdling cankers on seedlings during pathogenicity testing. There may be a facultative relationship between the scale insect and C. pinea, forming an insect-pathogen complex that is contributing to tree dieback and significantly impacting regeneration dynamics.

Key Collaborators: Kamal Gandhi (University of Georgia), Chris Asaro (USDA Forest Service), Dave Coyle (Clemson University), Michelle Cram (USDA Forest Service), Rima Lucardi (USDA Forest Service), Sunny Lucas (USDA Forest Service), and Angela Mech (University of Maine)

Figure from Schulz et al. 2018. Forest Ecol Mgmt 423: 70-83.

As a McNair Scholar at the University of Missouri-Columbia, I assessed the effects of prescribed fire on arthropod diversity in the Missouri Ozark Highlands. Fire has long played a role in the dynamics of the unique forest ecosystems of the Missouri Ozarks. Now, prescribed fire is being used to mimic historic fire disturbances that create a more open understory. At the Little Black Conservation Area near Doniphan, MO, forest managers were trying to promote wild turkey populations. Wild turkey feed on an array of seeds and arthropods in these forests, so we wanted to assess the effect of prescribed fire and refugia on arthropod diversity. I collected samples of ground-dwelling arthropods using pitfall traps in three treatment areas (control, burned, island refugia). Overall, the island plots had the greatest abundance of arthropods and richness of insects, while the control plots had the greatest diversity and evenness. Unburned islands can be included to provide shelter for flightless insects that contribute to overall arthropod biodiversity and are a key dietary component of wild turkey in these habitats.

Key Collaborators: Rose-Marie Muzika (University of Missouri; current: Carnegie Museum of Natural History) and Lizzie Wright (University of Missouri; current: Sugar Camp Farm)