Ecological thresholds and patterns of millennial-scale variability: the response of vegetation in Greece during the last glacial period

The regional expression of millennial-scale climate variability during the last glacial is examined with particular reference to the vegetation response in Greece. Inspection of three pollen records from contrasting bioclimatic areas suggests that differences in the magnitude of cold events as recognized in the North Atlantic and Western Mediterranean are expressed in terms of tree population changes only in areas with a range of favourable habitats. By contrast, records from sites where populations approach their tolerance threshold do not appear to resolve differences in the amplitude of the climate oscillations. Understanding the importance of local factors in modulating the biological response to climate change is critical when attempting to establish the spatial pattern of millennial variability.