Research

Lightning-tree interactions

Although lightning damages millions of trees each year, our understanding of lightning-caused mortality relies on anecdotal information.  Lightning is commonly associated with wildfires and these fires are an important consequence of lightning.  However, approximately 99% of lightning strikes do not cause fires and this percentage increases in tropical forests where lightning frequency is highest.  Our research explores the ecological effects of these strikes that do not cause fires.

How does lightning kill trees and why does it typically kill some trees but not others?  I am investigating phenomena related to this question as a postdoctoral associate working with Dr. Steve Yanoviak.  This ongoing work has demonstrated that lightning typically causes group tree mortality in a neotropical forest, and our results show that it is a major cause of large tree death.  I am interested in how the electrical properties of trees influence tree response to lightning and how lightning strikes induce post-strike invasion by deleterious invertebrates and microbes.  Using field-collected electrical data, we modeled lightning-tree interactions and are now collecting empirical evidence to test the predictions of this model in central Panama.  We are also using these field data to quantify the effects of lightning on dead wood production and carbon cycling.  This work is funded by National Science Foundation grants to myself, Dr. Steve Yanoviak, and Dr. Philip Bitzer, and a grant from the National Geographic Society to myself.

IMG_0221

Pictured are a large group of trees directly killed by lightning in Peru.  Locations where electric current jumped between branches in the canopy are noticeable between the branches in adjacent tree crowns.

Distant lightning strike

This image of a lightning strike was captured by our lightning triangulation system.  We combine images like this from multiple cameras to triangulate lightning strikes and quantify their ecological effects.

Carbon Cycling and Decomposition

Tropical forests are disproportionately important to the global carbon cycle and the vast majority of aboveground carbon is stored in woody tissues.  This carbon is released as dead wood decomposes, yet the process of wood decomposition is poorly studied in tropical forests.  I am investigating the distribution and decomposition of dead wood in tropical forests.

I am using a variety of approaches to study the roles of dead wood in tropical forests.  In a collaboration with Emma Sayer, Ed Tanner, and Ben Turner, we used a long-term litter removal and addition experiment to determine how soil nutrient availability affects decomposition over a 15 year period.  Separately, I worked with Helene Muller-Landau to quantify the stocks, fluxes, and spatiotemporal variability of dead wood on Barro Colorado Island in Panama.  We found that ca. 50% of wood necromass is separated from the soil, yet we know almost nothing about decomposition above the forest floor.  To address this knowledge gap, I am investigating how decomposition rates change vertically and how these changes are associated with environmental factors (microclimate and nutrient availability) and microbial communities (bacteria, archaea, and fungi).  Microbial community assembly affects decomposition above the forest floor, but these communities also shape community dynamics once wood falls to the ground. I am investigating how priority effects of canopy-level microbial communities influence ground-level decomposer community assembly and function.  This work is funded by grants from the Smithsonian Tropical Research Institute and the National Science Foundation.

Swimming Behavior and Orientation

I worked with an undergraduate, Noah Gripshover (now a Masters student at the University of Cincinnati), to explore how ants orient and swim to escape from the surface of water.  We tested swimming behaviors of Carpenter ants (i.e., Camponotus pennsylvanicus) in an easily manipulated experimental arena.  This gave us the ability to manipulate visual cues and test how these ants use their eyes to orient.  Inspired by his work as an assistant, Noah initiated a new stage of this research comparing swimming performance and the roles of specific legs between common temperate forest ant species. This work is funded by two grants from the Carl C. Cornett Entomological Endowment Fund.