IV] FIELD WORK 25 



group of woodland, or else of a section of the main forest area, 

 in which case it may often consist of one drainage basin and be 

 bounded by a watershed. In any case, the block has natural 

 boundaries such as watersheds, rivers, or roads, and it is often 

 distinguished by a local name. It may be of any size and shape, 

 and has no connection with the system adopted for working the 

 forest. 



24. The compartment. 



The compartment is a subdivision of the block and forms the 

 permanent unit of area. In a British woodland a compartment 

 may be 10 acres in extent, and in a forest in Burma it may be 

 1000 acres. It depends on the size of the forest and the intensity 

 of working. Its shape should be compact and more or less rect- 

 angular. Its boundaries will be formed by natural features of 

 the ground, or by roads, rides, fire-lines, rivers, ridges, or, if 

 necessary,- by artificial lines. 



25. The sub-compartment. 



So far we have considered the compartment merely as a unit 

 of area, but we also have to find a unit of the crop which has 

 to be analysed and split up into silvicultural units. These wiU 

 therefore have to consist of subdivisions of the forest in which 

 the condition of the crop, its composition and age, and the soil 

 and situation, are sufficiently homogeneo.us for each of them to 

 be described as one unit of the crop. Now if the compartments 

 are small and are formed by the regular intersection of a network 

 of roads and lines, it is quite possible that the compartments 

 already formed in this way will also serve effectively as silvi- 

 cultural units for the purpose of affording a descriptive inventory 

 of the crop. It will, however, often be necessary to subdivide 

 our topographical compartments, because there will be found 

 notable variations in soil, or situation, or in the species, age or 

 condition of the crop. These subdivisions will be called sub- 

 compartments. They are not necessarily permanent, because 

 they are based on the nature of the crop standing on them at 

 the present time. The whole forest is thus split up into silvi- 

 cultural units, of no fixed size, but each containing a timber-crop 

 capable of being included in, and covered by, one description. 



