I 2 TRANSACTIONS OF ROYAL SCOTTISH ARBORICULTURAL SOCIETY. 



differ in light-demand from the natural ones, the artificial 

 element does not materially alter the character of the ground- 

 vegetation. If they do differ, the ground flora is necessarily 

 changed to some extent. 



(5) Woods entirely planted, after felling, with species distinct 

 from the original ones, e.g. larch replacing oak. Here again 

 the change in the flora depends on the character of the planted 

 trees and their distance apart. The change may be very slight 

 or very pronounced, but the relation of the ground flora to that 

 of the natural woods on the same type of soil is generally quite 

 evident. 



(6) Plantations on arable land, grassland, or heath. These, 

 when recent, are easy to distinguish from natural or semi-natural 

 woodlands, because the ground flora is poor and does not 

 consist of typical woodland species. How long it takes to 

 colonise a plantation, so that it cannot be distinguished from a 

 natural wood, is not as yet known. 



The authors then proceed to point out that of these types 

 the second and third are practically natural woods, and that in 

 practice it is not so difficult to recognise woods of the fourth 

 and fifth types as might be supposed. 



Woodlands in Relation to Climate. 



The results of botanical surveys in Britain indicate that 

 climate and atmospheric factors have less effect on woodlands 

 than is sometimes stated, but, on the other hand, soil factors are 

 more important than is generally realised. The two sets of 

 factors are, however, closely linked together. An interesting 

 case is given in the " Woodlands " paper, and we think the 

 observation is a new one. "The amount of water held by 

 the soil in a given climate depends primarily upon the texture 

 of the soil ; but with a wetter climate, i.e., with increased 

 atmospheric moisture and with greater precipitation, especially 

 a rainfall distributed over a greater number of days in the year, 

 the average amount of water actually present in a soil of given 

 texture is greater. Thus a ' light ' or relatively coarse-grained 

 soil, that would carry a 'dry' type of woodland in a relatively 

 dry climate, may bear a ' damp ' type of woodland in a very 

 moist climate." On the whole, however, the variations in 

 climate throughout Britain do not greatly affect the distribution 



