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Steve Yanoviak

by Steve Yanoviak (submitted on 11/5/13)

1) The Ecology of Lightning in Forests from Michigan to Peru

In collaboration with lightning scientists (Hugh Christian and Phillip Bitzer, University of Alabama at Huntsville), landscape ecologists (Greg Asner, Carnegie Institute), forest ecologists (Walter Carson, University of Pittsburgh), and materials engineers (Fuqian Yang, University of Kentucky), my lab currently is exploring the ecological role of lightning in forests from Michigan to the Peruvian Amazon.  We are testing the hypothesis that vines serve as natural lightning rods for trees by virtue of their narrow, emergent, highly conductive stems.  We are also testing the hypothesis that certain trees in tropical and temperate forests have physiological or structural traits that resist lightning strike damage. Preliminary results from Panama, Michigan and Kentucky show that vine stems have lower electrical resistivity than tree branches over a similar size range.  This summer we implemented the northernmost portion of the project in Michigan with funding from the Huron Mountain Wildlife Foundation.  Those results will be presented by my students at the Kentucky Academy of Science meeting next week. Over the longer term, we will quantify the effects of lightning strikes on arboreal flora and fauna (e.g., epiphytes and canopy ants), and will focus on predicting the ecological effects of increased lightning activity in forest canopies of a warmer world.

2) Biodiversity in the Tropical Rainforest Canopy

One major research objective of my lab is to measure the effects of liana (woody vine) abundance on canopy ant diversity in Panama.  We focus on ants and lianas because they are superabundant in the tropics, ecologically relevant, easily observed, and experimentally tractable.  Moreover, lianas are the one forest component that seems to be most sensitive to climate change.  This work is funded by a new NSF CAREER Award, which is supporting one of my PhD students (Max Adams) and providing field research experience in Panama for UofL undergraduates and Louisville K-12 teachers.  Our main objectives are twofold.  First, we are conducting a large-scale liana removal experiment (in collaboration with Dr. Stefan Schnitzer, University of Wisconsin-Milwaukee) to determine how tree-to-tree connections provided by lianas maintain ant diversity in individual tree crowns.  Second, we are exploring how ants behave on different types of plant stems in the forest.  Specifically, we are testing the hypothesis that ants use lianas as highways for foraging in the forest canopy, and that the roughness or smoothness of stems determines which ants can use them.  To test this, we are collaborating with two geographers/engineers (John Van Stan, Georgia Southern University and Del Levia, University of Delaware) to measure the surface properties of plant stems at microscopic scales using the latest laser scanning technologies. My students spend a large amount of time each summer climbing tall tropical trees and collecting ants 100' above the ground.

3) Exciting Ant Behaviors

My lab is responsible for two amazing discoveries about ants that live in trees.  First, canopy-dwelling ants can glide back to their home tree trunk (like Superman) during a fall.  This ongoing research includes three main collaborators: Robert Dudley (University of California-Berkeley), Michael Kaspari (University of Oklahoma), and Yonatan Munk (University of Washington), and has received significant international media attention, including Discover, Smithsonian, National Geographic, Animal Planet, The BBC, The New York Times, and others.  While working on gliding ants, we also discovered that many tropical canopy ants are expert swimmers -- they efficiently paddle their way across the water surface of flooded forests and escape on emergent plant stems.  This research is in progress and will soon be submitted for publication.  The results will be presented by UofL post-bac Marilyn Feil at the Entomological Society of America meeting in Austin, Texas next week.