Where Did Ireland's Trees Come From?

Abstract

Review of literature on glacial history indicates that all trees had to migrate into Ireland during the current interglacial (since 10,000 years ago). More diverse tree floras existed in Ireland in previous interglacials. The collation of palynological data from 32 sites indicates that the early tree invaders migrated from the south. Other data suggest that the Irish Sea was a barrier to later tree migrants. The evidence for land bridges and timing of isolation of Ireland is unclear, but early tree migration across the Celtic Sea may have been facilitated by a forebulge land-bridge model. Tree migration rates have been calculated, and these indicate that vectors must also have assisted in the migrations. Data on the genetic diversity of oak across Europe also support the proposed migration route into Ireland. Fraser J.G. Mitchell (e-mail: fraser.mitch