19 



Bole.— Means the trunk or stem of a tree, from the 

 ground to the point where its main branches are given off. 



Crown.— Means the collection of main branches over- 

 topping the bole. 



Leaf canopy.— Is the mass of foliage formed by the crowns 

 of a collection of trees. 



Regular and irregular forest. — The trees forming a crop 

 may be (a) of the same age or size or (6) of different ages or 

 sizes. In the former case, the crop is said to be regular or 

 single-aged ; in the latter, irregular or of mixed-ages. 



Some recent French writers have objected to these terms regular and irregular 

 on the ground that " regular ■' means "conformahle to rule." The terms, howeveJ, 

 seem to be generally accepted and understood, although "single-aged" and " mixed - 

 aged " are to be preferred. 



Forest in storeys. — Irregular crops may be composed of 

 stems of all ages and sizes confusedly mixed, as in forests 

 treated by the method of selection fellings ; or they may be 

 formed of trees of different ages rising above one another, as 

 in the case of coppice with standards. In the latter case, the 

 crop, from being arranged in tiers, is said to be in storeys. 



Principal and accessory species. — In a mixed crop the prin- 

 cipal species are those which, from their superior value, 

 their abundance or the prevailing conditions for their favour- 

 able growth, determine the method of treatment applied and 

 the age at which the crop is felled. The other valuable 

 species, well distributed throughout the forest, are called 

 accessory or auxiliary species. 



Minor produce. — All the products of a forest, other than 

 those of the principal or accessory species, are usually called 

 minor produce. 



Age.— The age of a regular or single-aged crop is the 

 mean age of the trees composing it. In a crop of mixed 

 ages, the age of the class (of trees of the principal species) 

 most numerously represented is generally taken and alluded 

 to as the predominant age. In the case of crops in storeys, 

 the age of each tier is generally separately stated. 



Pure and mixed crops.— The crop in a forest may consist of 

 one or of several species. In the former case it is said to be 

 a pure crop ; in the latter a mixed crop. 



Density. — The density of a crop is the degree of com- 

 pleteness of the leaf canopy of the trees that compose it. 

 This is usually expressed by a co-eflBcient, but may be de- 

 scribed by stating the species, the number of stems and 

 their age per unit of area. 



