title: Inference of allelopathy is complicated by effects of activated carbon on plant growth.
abstract: Allelopathy can play an important role in structuring plant communities, but allelopathic effects are often difficult to detect because many methods used to test for allelopathy can be confounded by experimental artifacts. The use of activated carbon, a technique for neutralizing allelopathic compounds, is now employed in tests for allelopathy; however, this technique also could produce large experimental artifacts. In three independent experiments, it was shown that adding activated carbon to potting media affected nutrient availability and plant growth. For most species tested, activated carbon increased plant biomass, even in the absence of the potentially allelopathic agent. The increased growth corresponded to increased plant nitrogen content, likely resulting from greater nitrogen availability. Activated carbon also affected nitrogen and other nutrient concentrations in soil media in the absence of plants. The observed effects of activated carbon on plant growth can confound its use to test for allelopathy. The detection of allelopathy relies on the difference between plant growth in medium with carbon and that in medium without carbon in the presence of the potentially allelopathic competitor; however, this difference may be biased if activated carbon alters soil nutrient availability and plant growth even in the absence of the focal allelopathic agent.
authors.affiliation: Center for Population Biology, University of California, Davis, CA 95616, USA.|Present address: Kellogg Biological Station and Department of Plant Biology, Michigan State University 3700 East Gull Lake Drive, Hickory Corners, MI 49060, USA.
authors.forename: Jennifer A
authors.initials: JA
authors.lastname: Lau
authors.affiliation: Department of Plant, Soil and Entomological Sciences, University of Idaho, Moscow, ID 83843-2339, USA.
authors.forename: Kenneth P
authors.initials: KP
authors.lastname: Puliafico
authors.affiliation: Center for Population Biology, University of California, Davis, CA 95616, USA.
authors.forename: Joseph A
authors.initials: JA
authors.lastname: Kopshever
authors.affiliation: Natural Resource Ecology Laboratory, Colorado State University, Fort Collins, CO 80523, USA.
authors.forename: Heidi
authors.initials: H
authors.lastname: Steltzer
authors.affiliation: Department of Bioagricultural Sciences and Pest Management and Graduate Degree Program in Ecology, Colorado State University, Fort Collins, CO 80523, USA.
authors.forename: Edward P
authors.initials: EP
authors.lastname: Jarvis
authors.affiliation: Department of Plant, Soil and Entomological Sciences, University of Idaho, Moscow, ID 83843-2339, USA.
authors.forename: Mark
authors.initials: M
authors.lastname: Schwarzländer
authors.affiliation: Center for Population Biology, University of California, Davis, CA 95616, USA.
authors.forename: Sharon Y
authors.initials: SY
authors.lastname: Strauss
authors.affiliation: Department of Bioagricultural Sciences and Pest Management and Graduate Degree Program in Ecology, Colorado State University, Fort Collins, CO 80523, USA.
authors.forename: Ruth A
authors.initials: RA
authors.lastname: Hufbauer
mesh_terms: D001682:Biological Availability; D002244:Carbon / Q000494:pharmacology*; D063245:Plant Development; D010944:Plants / Q000187:drug effects* / Q000378:metabolism; D012987:Soil
chemical_list: D012987:Soil; D002244:Carbon