51 DEVELOPMENT OF FOREST TREES. 



limited growing,' space, are e-apabli! of prt'servin<; a complete 

 cover up to an advanced age, such as silver lir, spruce, beech, 

 and also hornbeam. Much inferior in this respect are ash, 

 Scotch pine and larch, chiefly because they are light demand- 

 ing; also maple and sycamore. If to the demand for light 

 is added a strong tendency to develop branches, then the 

 interruption of the cover occurs early, as in the case of oak 

 (especially pedupculate) and sweet chestnut. This tendency 

 is the more pronounced, the less suited the locality is for the 

 species. 



r. Soil. 



The nature of the soil influences the shape of the trees in 

 the case of all species. Fresh, deep, fertile soils encourage 

 height growth. Shallow, rocky soils produce only short 

 stems with a tendency to divide the stem and develop 

 branches. 



(I. Sifuafion. 



The development of stem decreases with rising elevation, 

 while that of branches increases. At great elevations the 

 shape is reduced to that of a shrub or bush. Similar pheno- 

 mena are observed on proceeding north, and in localities 

 exposed to cold winds. Trees exposed to continuous strong 

 winds, as near the sea coast, assume often a one-sided shape. 



2. Height Groirth. 

 The energy of height growth differs not only according to 

 species, but is also subject to considerable modiflcations in the 

 case of one and the same species, according to tlie age of the 

 tree, the locality, method of formation and the treatment. 



(I. S/irries. 



Amongst the trees of Central l^^urope, si)ruce, silver flr, 

 larch and AVeymouth pine attain the (/natcst itcii/Jit ; they 

 ordinarily reach a height of 120 feet, and under favourable 

 conditions, much moi'u. 



