Optimal rotation age of pinus patula in government forest plantations in Tanzania
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Date
2021
Journal Title
Journal ISSN
Volume Title
Publisher
Tanzania Journal of Forestry and Nature Conservation
Abstract
A study to determine the optimal rotation age
of Pinus patula was conducted in five forest
plantations in Tanzania, i.e., Kawetire,
Kiwira,
North
Kilimanjaro,
West
Kilimanjaro and Meru. Growth and yield,
and mechanical properties data were
collected from compartments representing
age from 5 to 25 years. In addition, revenues
and management costs data were collected
for the purpose of determining the economic
rotation age. For the purpose of determining
the optimal rotation age based on growth and
yield, the following basic models were
developed: 1) site index curves model, 2)
height-D model, 3) Single tree volume
model, 4) Basal area growth model 5) stand
volume model, 6) mortality model, and 7)
simulation of thinning. Analysis of Variance
(ANOVA) was carried out to ascertain
whether the wood properties vary across age
classes. Economic analysis of rotation age
data involved computation of Net Present
Value (NPV). Growth and yield data
revealed irrespective of site class, P. patula
can be harvested at age of 18 years while
mechanical wood properties show that
harvesting ages range between 16 and 21
years. Based on NPV, the optimal age was 16
years. Therefore, it is recommended P.
patula be harvested at age of 18 years
irrespective of site class.
Description
Journal Article
Keywords
Growth and Yield Models, Mechanical Properties, Net Present Value, Rotation Age