Acid episodes decisive for plant performance

Plant growth response to a 2 week episode of pH 4.2+70 μM Al was tested in flowing solution, followed by 3 weeks of pH 4.5 without Al. Four different patterns of growth response were obtained: Galium odoratum was irreversibly damaged, Lamium galeobdolon was severly affected during the episode but recovered rapidly, Bromus benekenii was more or less unaffected, whether Deschampsia flexuosa was stimulated. Species competitive ability, under conditions where acid episodes occurs, will probably decrease in the order: stimulatad> unaffected> reversibly affected> irreversibly affected. It is concluded that short acid episodes could be decisive for plant performance.