142 LOBLOLLY OR NORTH CAROLINA PINE. 



Open Pure Uneven-aged Stands. 



The per cent of increase in the value of the individual tree can also 

 be applied in fixing a diameter limit for cutting in open pure or slightly 

 mixed uneven-aged stands or groups in which the openness is caused 

 by fires and unregulated cutting. Table 73 gives the rate per cent of 

 increase in value for one inch increase in diameter of the dominant 

 trees in irregular open stands on different quality sites. The diameters 

 which correspond to a six per cent rate of increase are 18 inches on 

 Quality I, 17 inches on Quality IT, and 16 inches on Quality III. 



DETERMINATION OF YIELD. 



One of the most important problems in connection with the proper 

 management of loblolly pine lands is the determination of the yield 

 which could be secured from a tract within a definite period; or in the 

 case of larger tracts, it might be desirable to know the amount of timber 

 which could be felled yearly to supply a mill without lessening the 

 producing capacity of the forest during a subsequent period. 



In the case of small tracts which are fully stocked, the quality site 

 can be ascertained and the yield determined from the yield tables for 

 the class of timber desired, and the age at which it would be necessary 

 to fell. 



In the case of large tracts, not only Avill it be necessary to map and 

 determine the areas of the different forest types and quality sites, but to 

 indicate the age and condition of each stand. Waste and unproductive 

 land and young stands from Avhich no yield can be expected within the 

 period to be considered should be eliminated. The productive lands 

 should be grouped according to their growing capacity, and the quantity 

 of the material into : 



1. Yery open, pure, even-aged stands in Avhich the trees are somewhat 

 short-bodied. The vield of these stands can be obtained by means of 

 Table 73. 



2. Pure, even-aged sapling and pole stands of good density. The 

 yields of these can be secured direct from the yield tables. (Tables 

 35 to 41.) 



3. Pure and mixed old stands. Growth is practically stationary in 

 such stands, such increment as takes place in young trees being bal- 

 anced by the death or decay of old ones. 



4. Mixed young and middle-aged stands ; and pure, uneven-aged 

 stands, which usually have been culled, but the trees in which have 

 stems of nearly normal length. By means of Table 73 it is possible 

 to determine approximately the smallest sized dominant trees of loblolly 

 pine which will attain merchantable diameter by a designated year. 

 Trees of this diameter and larger can be tallied on a known percentage 



