Chemical Ecology is the study of the role of chemical substances in mediating
relationships between organisms. My particular interest is in the phenomenon of
allelopathy, or chemical interference among higher plants. 

It has long been suspected that toxic chemicals released by plants into the soil may
function as natural herbicides to inhibit the growth of neighboring plants. If this is
the case, such chemicals could influence important ecological processes such as
successional changes in plant communities over time, and nutrient cycles. Recently, it
has been proposed that the success of certain invasive plants might be due to the
chemical toxins they produce. One of the major barriers to evaluating these ideas has
been the difficulty of analyzing the release of these chemicals in the soil. My recent
work focuses on the development and application of new polymer-based materials such as
polydimethylsiloxanes that can trap these chemicals as they are released in the soil,
allowing these toxins to be isolated and measured. This research will provide an
inexpensive tool for other scientists to use in investigating these problems. This work
is funded by the National Science Foundation, Division of Ecological Biology. 

The broader implications of this project are two-fold. First, understanding how chemicals
released by plants do or do not function as natural herbicides may suggest new ways to
manage and control certain invasive species that have caused widespread damage to natural
and managed land. In agriculture, such chemicals might be used as more ecologically-sound
replacements for synthetic herbicides. 

In addition to my currently funded work on rhizosphere analysis, a significant portion of
my previous research has been in the area of greenhouse and field methods for studies of
chemical interference between plants. It has proven extraordinarily difficult to
demonstrate that the inhibition of plant growth observed in the field or greenhouse are
due to toxic chemicals being released by a neighbor, and not due to effects such as
competition for moisture and nutrients. We have found that phytotoxic effects are
density-dependent at low plant densities, there is more of the toxin available per plant
and therefore a greater toxic effect than is observed at higher densities. This sort of
response is inconsistent with resource competition. 

Allelopathy -- Research Methods


Plant growth responses to inorganic environmental contaminants are density-dependent: Experiments with copper sulfate, barley and lettuce (with Mari Hansi and Ari Sinkkonen), Environmental Pollution (2014)

The density-dependence of terrestrial plant-plant interactions in the presence of toxins has previously been explored...



Evidence does not support a role for gallic acid in Phragmites australis invasion success (with Mei Li, Joshua Allman, Robert G. Bergosh, and Mason Posner), Journal of Chemical Ecology (2013)

Gallic acid has been reported to be responsible for the invasive success of nonnative genotypes...



Fungal superhighways: do common mycorrhizal networks enhance belowground communication? (with E K. Barto and D Cipollini), Trends in Plant Science (2012)

In many natural communities communication between plants and other organisms below ground drives community dynamics....



The fungal fast lane: Common mycorrhizal networks extend bioactive zones of allelochemicals in soils (with E K. Barto, M Hilker, F Muller, Brian B, and J Rillig), PLoS ONE (2011)


Direct and indirect effects of invasive plants on soil chemistry and ecosystem function (with Ragan M. Callaway), Journal of Chemical Ecology (2010)

Invasive plants have a multitude of impacts on plant communities through their direct and indirect...


Allelopathic Effects of Florida Scrub Perennials


Constituents of Calamintha ashei: effects on Florida sandhill species (with M. A. Menelaou, H. P. Henandez, F. A. Macias, G. B. Williamson, F. R. Fronczek, H. D. Fischer, and N. H. Fischer), Natural Product Communications (2010)

Chemical constituents of the perennial shrub Calamintha ashei have been characterized as part of our...



Allelochemicals as a mechanism for resisting invasion: the case of polygonella myriophylla (with John Romeo), Invasive Plants: Ecological and Agricultural Aspects (2005)


Allelochemicals of polygonella myriophylla: chemistry and soil degradation (with John Romeo), Journal of Chemical Ecology (2004)

Gallic acid and hydroquinone have been identified as the major allelochemicals of the known allelopathic...


Lead Contamination


Bioavailability of Cadmium in inexpensive jewelry (with Jennifer Miller, Daphne Guinn, and Janna Pearson), Environmental Health Perspectives (2011)

BACKGROUND: High cadmium (Cd) concentrations have recently been found in some inexpensive jewelry. In response,...



Assessment of leaching potential of highly leaded jewelry (with B E. Newman and A Clever), Journal of Hazardous Materials (2010)

Lead is a potent neurotoxin particularly toxic to young children, and in response to recent...



Lead contamination of inexpensive seasonal and holiday products., The Science of the Total Environment (2009)

Lead is a potent neurotoxin and because of this, the US regulatory limit for lead...



Lead contamination of inexpensive plastic jewelry (with Jamie L. Yost), Science of the total environment (2008)

The neurological hazards of lead to children are well-known. As a result of recent documented...



Evidence of recycling of lead battery waste into highly leaded jewelry (with Micheal L. Clement), Chemosphere (2007)

Inexpensive highly leaded jewelry, much of it imported from China, remains widely available in the...