Patterns of post-glacial spread and the extent of glacial refugia of European beech (Fagus sylvatica)

Aim Establishing possible relationships between the magnitudes of the glacial distribution of the European beech, Fagus sylvatica L., and its post-glacial spread. Location Europe. Methods A database of over 400 pollen records has been used to locate Fagus populations at the end of the last glacial and during the post-glacial in Europe and to assess the areal extent of their past distribution. Results The rate of late-glacial and post-glacial increase in the number of pollen sites where Fagus was locally present conforms well to a logistic model of population growth. This suggests that the area occupied by beech populations expanded exponentially from the glacial refugia for a duration of over 10,000 years, until about 3500 yr BP. In the past three millennia beech populations increased at a slower rate, tending towards an equilibrium value. Main conclusions The conformity of the increase in beech distribution to the classical logistic model of population growth indicates that: (1) a multiplicative biological process was the main factor shaping the pattern of the post-glacial expansion of F. sylvatica in Europe, (2) climate conditions, human activity and competition may have influenced its rate of spread, and (3) beech populations did not expand with a moving closed front, but with a diffuse spread from scattered nuclei. The distribution of Fagus in Europe at the end of the last glacial appears to have been of two orders of magnitude less extensive than at present. Pleistocene refugia were likely to have been a mosaic of sparse stands of small populations scattered in multiple regions. Fagus populations appear to have increased very slowly and to a moderate extent in southern Europe, where they are now declining slightly. The central European populations increased quickly and extensively, reaching northern Europe, and are now approaching their carrying capacity

Decline and localized extinction of a major raised bog species across the British Isles: evidence for associated land-use intensification

The decline of S. austinii Sull. Ex Aust. (formerly S. imbricatum Hornsch. Ex Russ. ssp. austinii Sull. Abstract: The decline of S. austinii Sull. represents one of the most striking vegetation Russ. ssp. on the raised Ex Aust.), in most cases to local extinction, represents one of the most striking vegetation changes on the raised bogs of Britain and Northwest Europe during the last 2000 years. This study uses plant macrofossil, pollen and geochemical analyses to explore the record of human impact and land-use intensification at the S. austinii decline. There is a clear temporal association between anthropogenic woodland clearance, cereal cultivation, soil erosion and contemporary climatic change, with the decline of S. austinii. These findings suggest that S. austinii is sensitive not only to rapid climate changes but also to the aerial deposition of soil dust and/or accompanying pollutants. A modern comparison of atmospherically derived nitrogen (N) loadings with the present presence/absence of S. austinii on 16 raised bogs shows that the species is only present where the loading lies below a critical threshold for N of 10 kg/ha per yr. The palaeoecological record also shows that S. austinii has re-established itself during phases of reduced human activity but in contemporary Europe it is difficult to see this happening in the near future

A multiproxy approach to the function of postmedieval ridge-and-furrow cultivation in upland northern Britain

The remains of agricultural activity preserved beneath current rough pasture in the uplands of Tweed dale in southern Scotland are subjected to multidisciplinary analysis by archaeological survey, documentary research, and palaeoecological reconstruction through pollen analysis, supported by 210Pb and other forms of dating. The survey showed the features to represent grooved rig, a form of ploughing presumed to be related to cereal cultivation in the medieval and postmedieval periods. Documentary and pollen analyses suggest, however, that the ploughing is very recent, of nineteenth-century date, and represents a form of pasture improve ment for sheep grazing. This conclusion demonstrates the value of multidisciplinary research based on this type of evidence, and has implications for the interpretation of comparable forms of upland agriculture