NOTES FROM OAK AND BEECH FORESTS IN DENMARK. 247 



forest soils, was made and preserved so long as oak forest retained 

 its place. Enclosure of land for agriculture has almost ex- 

 terminated the old oak forest in Northern Europe, because in it 

 the earlier settlers found the better soils, shelter, and other con- 

 ditions favourable to their needs. Another rival of the oak 

 appeared when the beech gradually migrated northwards into the 

 oak forests. This stage of the natural sequence cannot be 

 followed out in Scotland where the beech is only a planted tree, 

 so that we again quote P. E. Miiller : — 



" The old Jutlandic oak woods on sandy soil have in many 

 places been able to withstand the invasion of the heath (heather, 

 etc ), and have preserved the ' muld ' character of the soil for 

 thousands of years, for they must be regarded as the direct 

 descendants of the extensive oak woods of the post-glacial 

 period before the late immigration of the beech. Even in 

 historical times the woods in East Jutland have been such oak 

 woods with ' muld,' into which the beech has migrated. Now 

 the oak has quite disappeared as a plant association from these 

 woods, and the chief natural tree is the beech which in its 

 ascendency has transformed the ' muld ' of the soil into ' mor,' 

 and thus produced a condition in the humus soil which will 

 probably no longer permit the beech wood to renew itself without 

 the interference of man." 



The influence of oak wood in accumulating and preserving the 

 better class of humus may not be quite evident under Scottish 

 conditions. Our native oak woods are generally coppice, whereas 

 the reference above is to old oak forests, of which the Spessart 

 in Bavaria is an example often referred to in works on forestry. 

 Oak coppice, on the other hand, does not usually preserve the 

 humus as "muld." The periodic cutting of coppice leaves the 

 soil exposed to sun, wind and weather, so that the "muld' is 

 destroyed. In extreme cases the soil may be exposed, and 

 becomes crusted or loose, according to its nature. Sometimes 

 the humus persists, but it is in the form of "mor," and the ground- 

 vegetation includes those species indicative of raw humus. The 

 woods in the Tay valley, for example, show all stages from 

 "muld" through "mor" to bare soil. The same is the case in 

 English oak woods, and in Types of British Vegetation (191 1, 

 Cambridge Press) the gradual change of the ground-vegetation 

 incidental to repeated coppicing has been recently described. 



