A Contribution to the History of Forest Clearance [and Discussion]

J. Turner, G. E. Fogg
1965 Proceedings of the Royal Society of London. Biological Sciences  
During the last five thousand years m an's activities have played an im portant and increasingly complex role in determining plant populations and habitats. His forest clearance and farming activities have long been recognized on pollen dia grams, usually by the presence of such pollen grains as those of cereals, plantain and other ruderals, and often, associated decreases in the tree pollen frequencies. However, the actual frequencies which change, and the amount by which they do so, varies
more » ... ey do so, varies from place to place and from time to time, and it is with this variation and its significance th a t we are here concerned. In general terms three basic questions must be asked about each example of human interference with the vegetation. First, exactly what is represented in terms of the changing plant communities, and why did they change? To answer this the successive changes in pollen frequencies must be very carefully defined by as close a sampling as possible. And there must also be a time scale for them, for knowledge of the time involved often becomes crucial for a fuller understanding of why the plant communities changed. Only a series of radiocarbon dates from each profile is really adequate for this purpose. Then, secondly, we want to know how large an area was being cleared and used. Was it just a few acres, or was it as much as a hundred square miles ? And finally, and perhaps most im portant of all, we want to know when these clearances occurred. Two places will not necessarily have the same history. Each area must be worked out separately before anything like a comprehensive picture can emerge for Britain as a whole. Small tem porary clearances The first impact on the woods to be recognized was described by Iversen (1949). He used the word landnam to denote a threefold episode of forest clearance, occupation and forest regeneration. Unfortunately, landnam has been used sub sequently for many different types of human interference with the vegetation, and so in referring to th at which Iversen described the term small temporary clearance will be used. Temporary, because the trees soon regenerated and the woodland quickly became much as it had been before, and small, because the amount of land involved could not have been very much. Some small temporary clearances at three sites, two in Wales, and one in Scotland will be compared. The first, shown in figure 22 , is that from Tregaron Bog in the Teifi valley in mid-Cardiganshire. The samples, numbered 1 to 32, are successive \ in. slices of peat taken from between 115 and 140 cm in the profile. The forest clearance is represented by the decrease in tree pollen and the increases in th at of grasses and plantain, and in bracken spores between samples 3 and 8. Between samples 9 and 18, where these latter frequencies remain high, is the occupation phase, and it is [ 343 ]
doi:10.1098/rspb.1965.0006 fatcat:6xyaq64blfah7cdu4cky4jkxvm