84 PLANTING 



pinaster, Plane trees, and Tulip trees. It seems to act as a 

 poison to them. 



Whereas, Beech, Ash, Corsican Pine, Austrian Pine, Yew, 

 Walnut, and Box distinctly prefer a calcareous soil. 



Larch usually prefers soils with plenty of lime in them, 

 though it never thrives where chalk is near the surface ; 

 this, however, cannot be attributed to the chemical com- 

 position of the soil or subsoil. 



So again, any acidity in the soil usually acts as a poispn 

 to trees. 



Land covered -with heather is usually too acid for the 

 broad-leaved trees, except Alder and Birch, to grow well in, 

 and only conifers should be planted, for the first rotation, on 

 such land. Though, if the heather has not been long 

 established, it would often suffice for broad-leaved trees. 

 Such a case might occur where arable land had gone out of 

 cultivation and the heather had only occupied the ground 

 for a few years. It is the acid contained on heather land 

 that is so often instrumental in forming a " pan." 



On these slightly sour soils, Birch, Alder, and the conifers 

 will succeed, if there be a sufficiency of moisture, and not an 

 excess of it. On the driest of such soils, only Birch, Scots, 

 Corsican, and Austrian Pines should be planted. 



Usually speaking, trees are very intolerant of poisons in 

 either the soil or the air. 



Near large towns and factories the atmosphere is often 

 laden with poisonous compounds. In such a case, deciduous 

 broad-leaved trees may often succeed when evergreen 

 trees fail. 



The Plane tree (which sheds its bark), Elm, Lime, Acacia, 

 Black Poplars, Horse Chestnut, and Sycamore are the best 

 trees to plant when such conditions prevail. 



On the other hand, Beech, of the broad-leaved trees, is 

 the most susceptible ; and of the conifers, Silver Fir. 



As to Heat and Warmth. The effects of heat on tree 

 growth are very varying ; for the determining point is so 

 often the amount of available moisture. No locality in this 

 country is too hot for tree growth, provided that there be a 



