Selected Yield Tables for 

 Plantations and Natural Stands in 

 Inland Northwest Forests 



Albert R. Stage 

 David L. Renner 

 Roger C. Chapman 



E»^TRODUCTION 



This report contains yield tables arrayed by site index 

 and age for average ecological and topographic situations 

 in the Inland Empire. Yields were estimated by the Prog- 

 nosis Model for Stand Development, version 5.2. Esti- 

 mates are provided for plantations of Douglas-fir {Pseu- 

 dotsuga menziesii), western larch {Larix occidentalis), and 

 grand fir {Abies grandis) and for natural stands in the 

 grand fir-cedar-hemlock ecosystem. Five thinning regimes 

 are presented for the plantations. 



Yield tables that represent estimates of volumes con- 

 tained in forest stands have traditionally been presented 

 with site index and stand age as the table stubs, and vari- 

 ous attributes of the expected stand — ^merchantable vo- 

 lumes, total volumes, basal area, and mean diameter at 

 breast height (d.b.h.) — ^in the body of the table. 



Site index is only one factor influencing future yields. 

 However, incorporating other productivity factors into the 

 format of conventional yield tables, along with a multiplic- 

 ity of alternative management regimes, would require 

 extremely voluminous sets of tables. The obvious solution 

 is to prepare the tables to specifications of the user with 

 the Prognosis Model (WykofFand others 1982). 



Some information needs are not met by such yield- 

 simulation procedures. In the most serious situation, the 

 existing inventory may have been designed to provide only 

 the traditional site index and age classification of the for- 

 est, precluding the use of the more definitive techniques. 



Another information need — comparing yields between 

 forest types or regions — ^is hampered if the forests being 

 compared are not described by the same variables. Al- 

 though site index and age definitions often vary from re- 

 gion to region and type to type, the problem is even more 

 serious when the additional site variables are not used at 

 all. 



For these reasons, users or potential users of the Prog- 

 nosis Model have asked to have yield information implicit 

 in the Prognosis Model presented in the traditional format 

 of site index and age. The tables in this publication are 

 intended to meet that request. 



APPLICABILITY 



The tables presented here represent the forests of the 

 Inland Empire, which includes northern Idaho, northeast- 

 em Washington, and western Montana. 



Within the Inland Empire, the tables for natural stands 

 represent the following habitat types: 



Grand fir/pachistima 

 Cedar/pachi stima 

 Hemlock/pachistima 

 Subalpine fir/pachistima 



Yield estimates for Douglas-fir plantations represent, in 

 addition to those for the naturally established stands, the 

 following habitats: 



Douglas-fir/ninebark 

 Douglas-fir/snowberry 

 Douglas-fir/pinegrass 

 Subalpine fir/menziesia 

 Subalpine fir/woodrush 

 Subalpine fir/twinflower 

 Mountain hemlock/menziesia 



Yield estimates for western larch plantations represent, 

 in addition to those for the naturally established stands, 

 the following habitats: 



Douglas-fir/ninebark 

 Spruce/pachistima 

 Grand fir/beargrass 

 Subalpine fir/devil's club 

 Subalpine fir/beargrass 

 Subalpine fir/twinflower 

 Subalpine fir/whortleberry 

 Mountain hemlock/beargrass 

 Mountain hemlock/menziesia 



Yield estimates for grand fir plantations represent, in 

 addition to those for the naturally established stands, the 

 following habitats: 



Grand fir/beargrass 

 Subalpine fir/menziesia 

 Subalpine fir/beargrass 

 Mountain hemlock/beargrass 



Five management regimes are represented for planta- 

 tions of each of the three species. Planting density and 

 initial survival are assumed to provide 500 trees per acre 5 

 years after planting. In parentheses after each regime is a 

 mnemonic code used to identify the regime on those figures 

 that compare several regimes. 



1. No thinning (000). 



2. Precommercial thinning fi*om below at 20 years to 250 

 trees per acre (POO). 



1 



