Yield of Cupressus lusitanica in Ethiopia

1993

S. 195-207

14 Lit. Ang.

Unselbständiges Werk

200040933

Yield of Cupressus lusitanica Mill. was modelled by predicting the diameter distribution of trees at given stand ages. The beta distribution was used as a theoretical distribution. The models used for the calculation of diameter distribution were based on 66 temporary sample plots with varying age, site and stand density. The growing sites of Cupressus lusitanica were divided into four classes on the basis of age and dominant height. Using the stand models developed in the study, the yield and profitability of different thinning schedules was evaluated by a simulation technique. In the simulated treatment regimes the mean annual increment varied from 6.6 Kubikmeter/ha in the poorest site class to 16.6 Kubikmeter/ha in the best class with rotation lengths ranging from 25 years (best sites) to 34 years (poorest sites). With typical planting densities (1600 trees/ha), thinnings increase the total harvest by a few percentage points and improve the profitability of plantation forestry.