A long-term perspective on ungulate-vegetation interactions

The fossil record of vegetation and ungulates places present conditions and trends in a temporal perspective. Ungulate-vegetation interactions during the last 500 000 years were primarily driven by the climatic variation of the glacial-interglacial cycle. There were distinctive faunas associated with each temperate period and a loss of species diversity only in the present interglacial. Climate change and human activities have interacted during the most recent glacial cycle, accelerating extinction rates. This unique course of events has the consequence that no stable, 'base-line' conditions can be recognised. A review of the full-glacial 'mammoth-steppe' debate suggests that ungulate populations were limited by available forage, but a mosaic of habitat supported a diverse fauna in Beringia. In the debate over early-mid Holocene 'wood pasture', past ungulate populations are one of a range of disturbance factors, including burning, that influenced regional vegetation composition and structure in northern Europe. These debates concerning the scale and impacts of past ungulate-vegetation interactions will not be fully resolved until more is known about past ungulate population sizes. Modelling past scenarios would enhance the value of retrospective studies and help provide goals for management of near-natural ecosystems. (C) 2003 Published by Elsevier Science B.V.