CHAPTER IV. 



SPECIFIC COMPOSITION OF FOREST CROPS- 



Ought we to grow pure or mixed forests ? This question has 

 already been partially answered in an incidental manner in Chap- 

 ter II ; but it is of such importance to the forester, that it demands 

 special and fuller treatment here. 



As said before, a forest may be grown either exclusively for the 

 market, or essentially and chiefly for purposes of protection, or 

 in combination with grazing or field-crops, or essentially and chiefly 

 for ornament. The answer to the question which opens this Chap- 

 ter must hence be sought separately in each of these three several 

 cases. But before attempting to do so, it is necessary first of all 

 to enquire what peculiar advantages or disadvantages accompany 

 the mixing of species, or the growing of them pure. 



SECTION I. 

 Characteristics of pure and mixed crops compared. 



The advantages to be derived from growing mixed, as compared 

 with pure crops, are briefly as follow : 



/. A mixture of species generally allows of a more complete 

 utilisation of the area. It rarely, if ever, happens that the soil and 

 climatic factors over any area, however inconsiderable it may be, 

 are suited only for a single species, or capable at every point of 

 growing that one species better than all others. Hence with a mix- 

 ture of species it is alwayss possible to grow at any particular point 

 only those species which thrive well there, and thus turn the entire 

 area to the best account possible. See also bottom of page 49. 



L Jr o 



//. Mixed crops, as a rule, form a denser leaf-canopy. In a 

 mixed forest the various species attain different statures, develop 

 crowns of different shapes and width and depth, are shade-endur- 

 ing or shade-avoiding in different degrees, possess foliage of vari- 

 ous degrees of closeness, affect or prefer different soils and situ- 

 ations, bring out and shed their leaves at different times, and so 

 on. The obvious result is that the leaf-canopy is then composed of 

 crowns of various shapes and sizes, situated at various heights 

 above the ground, and fitting into one another not unlike the 



