Chapter I 

 INVENTORY CONCEPTS AND PROCEDURES 



A 



To study the forest-range resource in a sys- 

 tematic manner, it was first necessary to estab- 

 lish a uniform framework of land inventory, 

 management strategies, and outputs suitable 

 for all sectors and within the bounds of com- 

 putational procedures. These procedures are 

 explained in this chapter. 



Most of the concepts and methods were con- 

 ceived under direction of the forest-range task 

 force. Special tasks, such as describing eco- 

 systems, defining and developing management 

 strategies, and estimating resource responses, 

 were carried out by teams of USDA Forest 

 Service experts. Models and computer pro- 

 grams were developed by the Forest Service 

 and the Economic Research Service of the 

 USDA, and the University of Nebraska Com- 

 puting Center, Lincoln, Nebraska. 



LAND INVENTORY 



The term "forest-range" covers all land in 

 the 48 conterminous States that is in native 

 and natural grasslands and commercial and 

 noncommercial forest lands, if at some stage 

 of their natural succession, or if under man- 

 agement, they produce vegetation that is graze- 

 able by livestock. Desert areas such as salt flats 

 and playas, and barren areas above treeline also 

 were included. Excluded were urban lands, 

 transportation system lands, improved pasture, 

 croplands, and major waterways. 



Areas called "resource units" were formed 

 to establish ecological units that would be rela- 

 tively homogeneous at the national level. The 

 intent was to provide a set of land units for 

 which present productivity of range outputs 

 could be estimated, and for which future out- 

 puts under varying levels of management could 

 be predicted. To accomplish this, each resource 

 unit was classified according to 34 ecosystems, 

 3 ownerships, 4 productivity classes, and 3 con- 

 dition classes. A resource unit as used in this 

 report is, thus, an area of land within one of 

 the 34 ecosystems, under one of 3 ownerships, 

 and in one of 4 productivity classes and 3 con- 

 dition classes. 



The ecosystem classification was adapted 

 from the work of A. W. Kiichler (1964). He 

 classified the United States into 106 maior 

 plant communities (phytocenoses) based on the 

 natural vegetation that would exist if man were 

 removed from the scene and the resulting plant 

 succession telescoped into a single moment. 

 Although many of his major plant communities 

 are presently managed so that they will not 

 evolve, his concept provided a basic common 

 denominator to reflect the biological potential. 



To simplify data compilations, two major 

 modifications were made of Kiichler's classi- 

 fication to form the 34 ecosystems: ^ 



(1) Closely related Kiichler types were com- 

 bined into single ecosystems. 



" A brief description of each ecosystem and correla- 

 tion of the ecosystems with Kiichler's classes is pre- 

 sented in Appendix A. 



