2l8 TRANSACTIONS OF ROYAL SCOTTISH ARBORICULTURAL SOCIETY. 



As regards saltpetre, which is really of very small importance 

 in forest soils, he was satisfied with qualitative analysis, which 

 as often as not gave negative results. 



Whilst carrying on these biological researches he proceeded 

 with investigations regarding the physical conditions of the 

 soils, their porosity and behaviour towards moisture and air. 

 The drying-up of the surface soil in the afforestation of old 

 fields he found to be so extreme that the ground was frequently 

 unable to supply any more moisture to the trees. It was at 

 one time considered that this was the only cause of the dying 

 of pine cultivations on such soils, but as the same drying-up 

 happened, no doubt, to a somewhat less extent, on heather- 

 covered afforestation areas, it was assumed that besides the 

 drying-up of the soil some other reason existed for the large 

 death rate. 



Albert made, however, upwards of 1200 careful experiments 

 in the Miinster forest division alone, in regard to the conditions 

 of moisture in soils under different cover. The results of these 

 have now led him to the opinion that the early deaths and 

 rapid opening out on Scots pine afforestation on all but bo?ia 

 fide forest soils, is in almost every case not merely partially 

 but entirely due to want of moisture in the upper layers of the 

 soil. The roots of the young pine, spreading out in the surface 

 soil, consume the moisture therein in proportion to the density of 

 the crop, till there is no longer sufficient to go round, and a 

 large number dry up. Those that are left, having individually 

 more water at their disposal, gradually adapt themselves to the 

 conditions and send, by and by, roots deeper down into the soil. 

 Where natural regeneration has taken place in exactly similar 

 localities no deaths among the young trees are observed, clearly 

 proving that the deaths in artificial afforestation are not due to 

 anything in the soil itself. The healthy existence of a large 

 number of closely packed trees of the same or similar species, 

 resulting from artificial afforestation, is only conceivable on old 

 bona fide forest soils where, by the rotting of old roots, channels 

 have formed, leading into the strata below the immediate 

 surface. 



Albert was always sceptical in regard to the theory that the 

 insufficiency of air in heather soils was one of the chief causes 

 of the diseases and premature deaths in Scots pine afforestation ; 

 but it was put forward with such authority by P. Graebner, who. 



