320 APPENDIX 



Mature forest. A forest or stand which has reached its age of utilization 

 (commercially). The meaning of maturity differs with the object of 

 management, and to the forester is a matter of calculation on various 

 bases. Biologically, maturity would refer to the age of seed produc- 

 tion; physically, to cessation of height growth. Financial maturity is 

 attained when the highest forest income or interest (which occurs when 

 the index per cent is equal to the demanded business per cent), or forest 

 rent, or soil rent, or otherwise financially best results can be secured. 

 After this point of maximum result is passed the forest income decreases 

 and the forest is said to be " financially overmature." See also Rotation. 

 Syn.: ripe. 

 G., finanzieUe Hiebsreife. 



Mean annual forest per cent. See Forest per cent. 



Mean annual increment. See Increment. 



Mean sample tree. A tree of representative form which in diameter, 

 height, and volimie is an average of the trees in a group or stand. 



Medium. See Crown density. 



Merchantable. A term to designate the portion of trees or stands which 

 can be marketed imder given economic conditions, usually refers to 

 log material only. 

 Merchantable length refers to the marketable length of log in a tree. 

 Merchantable volume refers to the marketable volume. 



Merchantable form factor. See Form factor. 



Middle forest. (Obs.) See Composite forest. 



Mild humus. See Humus. 



Mixed forest. Forest composed of trees of two or more species. In 

 practice tisuaUy a forest in which at least 20 per cent are trees of other 

 than the leading species. 

 G., gemischter Bestand. F., peuplement melange. 



Model forest. See Normal forest. 



Mother tree. See Seed tree. 



Mound planting. See Forest planting. 



Natural pruning. See Pruning. 



Natural reproduction. See Reproduction. 



Net income. See Income. 



Normal. Used as in common parlance in varying sense as conforming to 

 a standard, rule or principle, a model, or as denoting an average of 

 conditions, or the best of conditions. 



