The representation of allelopathy in ecosystem-level forest models

Allelopathy is one of the factors that determine interactions among plants. Allelochemicals have been found in many forest ecosystems, but the importance of allelopathy depends on forest type and environmental conditions. Despite the wide presence of this phenomenon, few forest models have incorporated a representation of allelopathy, but its inclusion should be considered in forest models dealing with environmental stress, exotic plant invasions and ecological succession. Multiple factors influence allelochemical production and toxicity, including nutrient availability, soil moisture and texture, solar radiation, and temperature. Ecosystem-level effects of allelopathy include changes in germination rates, inhibition of seedling growth, mycorrhizal function, insect and bacterial growth, inhibition of nitrification or litterfall decomposition and dieback of mature trees. To illustrate some potential consequences of incorporation some aspects of allelopathy, in an ecosystem-level model, a virtual experiment was carried out with the forest ecosystem-level model FORECAST. This revealed different effects of allelopathy on several ecological variables depending on the type of allelopathic influence simulated. In addition, this experiment showed the utility of ecosystem-level models to simulate, if not directly the allelopathic interactions, at least the ecological effects of allelopathy at the ecosystem level. Overall, my work points out that researchers and forest managers should think carefully about the need to include allelopathy as a way of improving the accuracy of forest models and ecosystem-based decision support tools. (C) 2007 Elsevier B.V. All rights reserved.