DISCUSSION ON PLANTING DISTANCES. 3 



been well said that ' he who plants trees must look on the 

 outcome of his labours with the eye of faith.' 



"As just stated the factors are so numerous that we can 

 only briefly deal with the most outstanding. 



" Rainfall plays no unimportant part in tree-growth, and while 

 we occasionally hear of the 'moist, insular climate of Great 

 Britain,' there are areas in this country where the paucity of 

 air- and soil-moisture checks growth. Certain areas are more 

 or less subjected to periods when the east wind prevails, with an 

 almost complete absence of precipitation. Seasonal rainfall 

 calls for soil protection to conserve moisture, and as the rate of 

 tree-growth increases rapidly when once proper canopy is formed, 

 it is evident, I think, that dry areas demand closer planting in 

 order that normal density may be attained at the earliest possible 

 period. Soil, in spite of ideas to the contrary, exercises a 

 certain influence on tree-growth. Beyond the mineral nutrients 

 contained in the soil, the physical properties have to be 

 considered. For example, light sandy soils that become readily 

 heated call for a closer planting distance than would be 

 advisable in the case of clay. 



"The sterile condition (as far as tree-growth is concerned) of 

 many new areas, compared with that of areas where replanting 

 is being done, points to the importance of producing canopy at 

 the earliest possible time. Once a soil becomes a ' forest soil ' 

 or a ' made soil ' there might probably be some reason for 

 maintaining that the soil, geologically speaking, does not 

 influence growth. It is customary to speak of an average soil, 

 and that may mean anything or nothing ! One may give it as 

 an average soil for a certain species, one for a certain district, 

 another for a certain altitude, etc. This leads to the mention 

 of such factors as elevation, exposure, aspect, and slope, but 

 while all these influence tree-growth to a greater or lesser 

 degree, time will not allow of more than the commonplace that, 

 generally speaking, the greater the altitude the closer the 

 planting should be. 



" I need hardly remind you that the attempts that have been 

 made to place trees in the categories oi fast and slo^v growing, 

 shade-bearing and light-demanding species, are based on rather 

 slender data, and are only relative terms when tested by the 

 above factors. Age is a decisive factor in these capacities. 



"The questions of form-factor (taper) and branch-formation 



