Thursday, June 14, 2012

Yellow Rattle Promotes Biodiversity

Yellow Rattle, Rhinanthus minor
Loss and fragmentation of semi natural habitats such as unimproved grasslands is a problem, not only in Ireland, but on a European scale, where it has accelerated in the the last 60 years (1). This has been largely attributed to agricultural intensification over this time, but the explosion in building in Ireland from c. 1997-2007 had its part to play. Schemes aimed at maintaining such species rich grasslands such as limiting fertilizer application and reducing grazing pressure and cutting frequency on existing swards have all been shown to have some benefits (2). 
Yellow Rattle, Rhinanthus minor
However, the introduction of the hemiparasite Yellow Rattle (Rhinanthus minor) may provide a more holistic approach to the problem of unimproved grassland loss. R. minor is common throughout Ireland, on undisturbed meadows and dunes. Its yellow flowers are visible now (and will be until September), borne on leafy, black spotted, terminal spikes (3). In a survey of five sites in Britain and Italy it was found that the presence of R. minor (and other Rhinanthus species) reduced the numbers of grasses present and increased the numbers of dicotyledons, resulting in an overall increase in plant biodiversity (2). These changes are due to the parasitic nature of R. minor, which resulted in an overall decrease in the productivity of the swards involved. While this could lead to problems with surrounding communities if R. minor were to invade them, these have been foreseen to be minimal as it has very low tolerance to high fertilizer applications, has limited seed dispersal and does not form a significant seed bank, thus minimizing its potential as an invasive agent. R. minor therefore may have considerable potential as a management tool for grassland restoration programmes (2).

  1. Critchley et al., 2003. Biological Conservation 115 pp. 263-278
  2. Davies et al., 1997. Biologwal Conservatwn 82 pp. 87-93
  3. Sterry, 2004. Collins Complete Guide to Irish Wildlife p. 242

1 comment:

  1. I had no idea of the role this plant played. I visited a local nature reserve on Sunday and noticed that the meadow was full of yellow rattle and that the grass cover was sparse but never linked the observations; too distracted by the mass of orchids! Thanks for educating me.