CHAPTER I. 



THE STRUGGLE FOR EXISTENCE IN A FOREST CROP- 



Of the plants produced in a forest only a comparatively small 

 number can live the full possible term of their individual lono-evitv. 



* O J 



As they develop, besides extending vertically upwards into the air 

 and downwards into the soil, they spread out laterally against each 

 other. Thus each one struggles to push out its neighbour. In 

 this mutual struggle for existence various extraneous circumstan- 

 ces, such as insects, the action of man, grazing, &c., also intervene 

 and exercise each its own influence on the longevity of the indivi- 

 dual plants. The result of these various causes operating together 

 is that some of the plants are continually dying off and disappear- 

 ing, only the fittest surviving until either natural decay and death 

 overtakes them or the exigencies of forest economy require their ex- 

 ploitation. In order to illustrate the preceding statement, we will, 

 in the absence of Indian examples, cite one from Germany, as 

 given by Theodor Hartig and quoted by Karl Gayer. The crop 

 experimented upon was a full canopied one of the European spruce 

 (Abies excelsa DC.) 

 At age 20 years there were per acre 9373 stems, of which 49 o/o under suppression, 



32 ,, 



5) "" 21 ,, 



>! 1 285 ., ,, 11 7J lt 



A study of the conditions which determine the result of the strug- 

 gle for existence is thus extremely complicated by the variety of the 

 inducing causes and by the different ways in which they may act 

 independently and conjointly one with another. Nevertheless it 

 may be very greatly simplified by examining separately the princi- 

 pal aspects under which the struggle may take place. In the first 

 place, a forest crop may be either pure or mixed, and in the second 

 place the crop, whether pure or mixed, may consist either of plants 

 of one and the same age, or of plants of different ages. In the last 

 case, the difference of ages may be slight, or it may be so marked 

 that the component plants include every age from the individual 

 just emerging from the seed to that fit for felling or on the point of 

 attaining the natural term of its longevity. Between these two 



