In this study, forest arrangement parameters were determined, with the purpose of incorporating criteria of permanent performance into forest management of a native forestland. The respective forest is Lenga (Nothofagus pumilio), pure multietanean structure, in little coetan forestland. As there is no knowledge of human actions over it, it represents the natural functioning of this forest type in dynamic balance state. The area was 511 hectares, determined as “Timber Harvest Area” in the territorial arrangement proposal of Mañihuales National Reserve, in the Aysén province, XI region of Chile. The calculus method used for the forest arrangement in the small and medium land was developed by the Forest National Corporation (CONAF), and proposes the definition of three basic parameters: volumetric exploitation rate (TA), Regeneration theoretic area (STr), and production balance. A TA of 5.8 m3/ha/year was determined, equivalent to a possibility of extraction of 14,984 m3/land/period for a period of 5 years. The STr calculated was of 5.4 hectares harvest/regeneration per year, or 27 hectares per the same period. Regarding the balance production, a balance factor of 77% was determined for the different states of the Lenga development in the land, whose practical effect in this case is the requirement of a low effort regulation. The forest management proposal adjustment to the mentioned parameters meant 56 hectares used in the forest management with a total yield of 15,064 m3, and 30 hectares harvested and their regeneration in this period. On the assumption of having a right forest performance the condition of the whole land was projected after 5 years. The balance factor improved on 5% (82% complete). Furthermore, the forestry proposals on the selected area had, as effect, a good adjustment to arrangement parameters in area as well as volume defined as guide.