Weather and survival of broadleaved dock (Rumex obtusifolius L.) in an unmanaged grassland

Survival of broad-leaved dock (Rumex obtusifolius L.) plants exposed to grass competition in unmanaged grassland in Central Europe was investigated. Individual plants (n = 244) were marked in 1999 and their mortality recorded twice a year, until 2007. Eight years of unrestricted competition with grass killed nearly all dock plants. Both winter mortality (October - April) and summer mortality (May - September) varied greatly between years. The numbers of plants dead during each of the periods were regressed against five meteorological factors that might affect dock mortality. Summer mortality increased with warm weather (mean temperature of 20 hottest days over summer period) and winter mortality increased with drought (number of days without precipitation during winter period). Water deficiency thus may be an important factor contributing to mortality of dock plants subjected to competition with grass.