The effects of winter exposure to acid soil conditions on the subsequent survival and growth of herbaceous, forest perennials: a preliminary investigation

For many plant species, growth is limited in acid soils, which are characte rized by high levels of potentially-toxic elements and low nutrient availab ility. Although plant-soil interactions are traditionally studied during th e growing season, the highest concentrations of toxic elements in the soil may occur during the winter months. The present study investigated the effe cts of a 3-month exposure to either an acid or a reference soil, at tempera tures fluctuating around freezing point, on subsequent survival and growth of eight herbs (Brachypodium sylvaticum, Carex pilulifera, Geum urbanum, Lu zula pilosa, Mycelis muralis, Silene dioica, Stellaria nemorum, Veronica of ficinalis). The plants were exposed to ambient weather conditions from Dece mber to March, after which they were replanted in fresh reference soil and transferred to a glasshouse. Their biomass was measured 5 weeks later. The plant species differed in their responses to the soils, in a manner reflect ing their natural field distributions. All plants of the most acid-tolerant species survived in both treatments, whereas the more sensitive species sh owed lower survival rates after growth in the acid than in the reference so il. Similar results were found for the regrowth: C. pilulifera and L. pilos a, the most acid-tolerant species, were unaffected by the soil treatments ( ratios between biomass in acid compared to reference soils were 0.8 and 1.1 , respectively), whereas G. urbanum, M. muralis, S. nemorum and V. officina lis were negatively affected (ratios 0.3-0.5). Effects on above- and below- ground biomass were broadly similar. This preliminary evidence indicates th at soil chemistry during the winter can be important for both survival and growth during the vegetative period that follows. (C) 1998 Annals of Botany Company.