Methodology of allelopathy research: 2. Forest ecosystems

Phenolic compounds are secondary metabolites widespread in plants and are leached from green foliage by rainfall and decomposing litter and thus teach the soil underneath the canopy. As allelopathic agents, phenolics from the donor plant affect the performance of target plants, either by inhibiting seed germination, root elongation or plant growth. In forest ecosystems, allelopathic effects of dominant trees on the understory species and also the understory species on tree seedlings and other plants in the plant community have been studied. Allelopathic effects of phenolic compounds of dominant species in forest ecosystems are assessed through laboratory bioassays, pot cultures and field studies. Laboratory bioassays include studies to evaluate allelopathic potential of a dominant species in forest community, inhibitory effects of dominant species and seasonal dynamics of phenolic compounds in forest community. Pot culture studies are done to study the inhibitory effects of soil under dominant herbaceous and tree plants in forest community. Field studies are done to study the effects of phenolics on PSII photosynthetic efficiency and chlorophyll content in plants, inhibitory effects of dominant species in degraded forest community and effects of phenolic compounds on natural regeneration process of forest trees. Current experimental methods to evaluate how tree, shrub or herbaceous plants use phenolic compounds to acquire a greater proportion of available resources and ways in which these allelochemicals can prevent the regeneration of forest ecosystems are discussed in this paper.nul