138 TRANSACTIONS OF ROYAL SCOTTISH ARBORICULTURAL SOCIETY. 



added another factor, the evidence of the natural vegetation, 

 which in practice is used by the forester to a considerable extent. 

 This suggestion is given, it is for the man in the field to decide 

 whether it is of any value. Too little has been done in that 

 direction to warrant a dogmatic attitude, but in a general way 

 there is evidence in favour of the supposition. One strong 

 argument against the value of the ground-vegetation as an 

 index of value of any site for tree-growth, is that the low-growing 

 plants are more or less surface-rooting, and therefore do not 

 give full information as to the lower soil-layers where the roots 

 of older trees would be. On the other hand, the following 

 points are put forward for consideration. 



If the originators of a certain report that " millions of acres " 

 were available for tree-planting saw the natural vegetation, a very 

 moderate experience of tree-growth would show how unsuitable 

 many square miles of Britain were. Where the natural vegetation 

 is pink bell-heath {Erica teiralix), cotton sedge (Eriophorum) 

 or deer-grass {Scirpus), an examination of the soil will show wet, 

 deep peat generally unfit for trees unless large sums are spent in 

 reclamation. Again, the presence of sedges, rushes, vvater plants 

 and bog moss is an indication of need of drainage before trees 

 can be grown successfully. The natural vegetation is thus a 

 fairly certain index of ground to be avoided in earlier experiments. 



Where there are both semi-natural woods and waste lands, 

 it has been observed that conditions which bring change in the 

 woods also affect the waste land. Thus, in north-east Yorkshire, 

 if one sets out from Helmsley and proceeds northwards up one of 

 the larger valleys {e.g. Beckdale), the first woods are strongly ash, 

 and the undergrowth includes a number of plants characteristic 

 of calcareous soils in that district ; oak is also present, while larch 

 is extensively planted and grows well. The adjoining farmland 

 on the calcareous Oolite soils is fertile, and uncultivated tracts of the 

 valley slopes, not wooded, are grass or scrub with lime-frequenting 

 plants. Higher up the valley a change is met. Ash diminishes 

 while oak and birch increase ; the undergrowth consists of 

 blaeberry, ling, and wavy hair-grass, plants of siliceous soils. 

 The adjoining farmland is poorish, and on considerable tracts of 

 treeless heath, ling is the most conspicuous plant, but on the 

 heathery moors Scots pine has been successfully planted. Apart 

 from the evidence of the trees, the natural vegetation in this area 

 gives good information as to the character of the soils. 



