CLASSIFYING FOREST SITES BY HEIGHT GROWTH 



By E. H. Frothingham 



U. S. Forest Service. 



THE NEED FOR SITE CLASSIFICATION 



A forest site, according to the Society's "Forest Terminology" of 

 1916,^ is "an area considered as to its physical factors with reference 

 to forest producing power; the combination of climatic and soil con- 

 ditions of an area." The prime reason for differentiating sites being, 

 however, the difference in their capacity to produce wood, this fills 

 the stage in practical work and forces the causative factors into a some- 

 what nebulous background. 



An inventory of lands considered as to wood-growing capacity has 

 initial importance in forestry. It is necessary at the outset in forest 

 management, in which land quality and market aft'ect every phase of 

 the business. It is one of the essentials for intelligent yield forecasts 

 and for the estimates of future income upon which present and future 

 expenses may be justified. In America the management of large 

 areas of forest land is waiting upon such inventories. 



There is, therefore, an urgent need for a simple method by which 

 sites may be quickly and easily classified. In order to classify sites 

 there must be some standard to measure by. The height growth of 

 dominant trees is an easily and widely applicable standard of measure- 

 ment. This paper will discuss Professor Roth's plan for site classifica- 

 tion by the height at a stated age, the role of height growth in general 

 as an indicator of site, and, finally, some of the features and possible 

 developments of the Roth plan. 



OUTLINE OF PROFESSOR ROTH's PLAN 



In his paper, "Concerning Site," ^ Professor Roth has outlined a 

 plan for site classification on a large scale. This plan would provide a 

 simple arrangement of site classes good for the whole country, or any 



^ Compiled by a committee of the Society of American Foresters and published 

 in the Journal of Forestry for January, 1917, Vol. 15, No. 1. 

 ''Forestry Quarterly, March, 1916, Vol. 14, No. 1, pp. 3-12. 



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