xvi The Trees of Great Britain and Ireland 



whether it has succeeded reasonably well in any place of similar soil and climate ; 

 and as we have recorded the accumulated experience of our predecessors, it may 

 usually be presumed that if no degree of success has been attained it is only a 

 waste of time and money to plant species which have died out or remained in a 

 stunted condition. Generally speaking it may be said that there are four principal 

 types of climate in Great Britain. 



The first is characterised by a high summer and a low winter temperature, 

 combined with a low average rainfall ; and this includes all those districts in which 

 wheat is the most important agricultural crop, namely the eastern counties as far 

 north as the Humber, and the southern counties as far west as Dorset and the 

 Severn Valley. In many parts of this region where, owing to the influence of 

 sea air or elevation, late spring and early autumn frosts rarely occur, the best 

 climatic conditions for the growth of most exotic trees are found. 



Secondly, the south-western counties and the maritime districts of Wales, the 

 greater part of Ireland and western Scotland, where the summer temperature is 

 lower and the winters shorter and milder, and where the rainfall and the humidity 

 of the air is much greater. In this region alone a great many of the rarer trees 

 and shrubs thrive wherever suitable soil and shelter from wind are found ; but the 

 trees which require a high summer temperature and abundant sunshine to ripen 

 their wood, such as walnuts, hickories, Catalpas, and many North American species, 

 are not often successful, and do not attain large dimensions or ripen their seeds 

 in normal seasons. 



Thirdly, the north-eastern and midland counties and those districts of southern 

 England where the summers are shorter, where late and early frosts are prevalent, 

 or where the soil is too heavy or too wet to suit a great many exotic trees ; but 

 many exceptions will be found in this region, especially near the sea, and in this 

 district may be included parts of Scotland bordering on the Moray Firth, where the 

 climate is distinctly more suitable to arboriculture than in the northern and midland 

 counties of England generally. 



Fourthly, the mountains of central and northern England, Wales, Scotland, and 

 Ireland, at elevations over looo feet, where only a few of the hardier conifers can be 

 grown with much hope of success. 



Next to climate, the geological formation and depth of the soil is the most 

 important factor in the successful growth of trees ; and this again is variable even in 

 the districts where climate is favourable ; so that we find the best instances of arbori- 

 culture are scattered in all parts of the country. Generally speaking, the soils which 

 produce the finest hardwoods are on the old red sandstone and lower greensand 

 formations ; and though some species attain a large size on other soils, yet wherever 

 heavy clay or thin rocky soils prevail, especially on limestone, many exotic trees will 

 not grow at all, or become stunted and unhealthy as soon as their roots get into the 

 subsoil. As a result of careful soil preparation trees may appear to thrive for a 

 number of years, yet they eventually become sickly or die if nature has not provided 

 a suitable subsoil. Want of knowledge or of attention to these two factors, has led 

 in the past to immense waste of time and money in planting trees which are quite 



