| PRODUCTIVITY
AND VOLUME ESTIMATES
The productivity of teak plantations has been studied across
a broad range of countries through permanent sample plots.
The earliest yield table for teak was constructed by von Wulfing
(1932) for plantations on Java, Indonesia. Laurie and Ram
(1939) constructed a yield table for teak plantations distributed
over present-day India, Myanmar and Bangladesh. More recently,
yield tables have been developed using data from permanent
and temporary sample plots for plantations of teak established
outside its natural range, including provisional yield tables
for Trinidad and Tobago (Miller, 1969), Côte d'Ivoire
(Maitre, 1983), Nigeria (Abayomi, 1984) and Sri Lanka (Phillips,
1995).
An important feature of all teak yield tables is the early
peak of mean annual volume increment (MAI), generally between
six and 20 years. Because teak is planted and managed for
timber production, size plays a decisive role in determining
harvesting, rather than the age of maximum volume production.
The rotation age of plantation teak in its natural range has
varied between 50 and 90 years, while outside its range the
rotation age is between 25 and 60 years. Table 2 compares
the MAI at 50 years (taken as the average age at harvest)
and at the age of maximum volume production, as derived from
the various yield tables.
There is a paucity of data on actual yield obtained at harvest
of teak from different site classes and countries. There is
limited data available from Indonesia and India. In Indonesia,
the average actual MAI at harvest age, with rotation varying
between 40 and 90 years, was 2.91 m3 per hectare per year
(FAO, 1986), while Table 2 estimates an average of 13.8 m3
per hectare per year. Perum Perhutani, the State-owned company
that manages the major teak plantation areas in Indonesia,
has confirmed that the actual yield of teak at final felling
is about 100 m3 per hectare at about 70 years, with a similar
volume obtained from thinnings. The MAI at rotation age is,
consequently, about 3 m3 per hectare per year (Perum Perhutani,
unpublished data).
Similarly, in India, the actual yield obtained from thinnings
and final fellings in Koni Forest in Kerala State averaged
172 m3 per hectare with a 70-year rotation, giving an MAI
of about 2.5 m3 per hectare per year (FAO, 1985). The site
class for teak in Koni Forest was considered to be between
the average and the best, but poor stocking was considered
the main reason for such a low yield. Similar yields were
also found during plantation inventory of teak in Bangladesh.
However, in teak plantation inventories in Benin and Ivory
Coast, the estimated MAI with a 40- to 50-year rotation age
was found to range between 8 and 11 m3 per hectare per year.
The estimated yield in Costa Rica with 40-year rotation is
6.9 m3 per hectare per year (M. Gomez, personal communication).
The general conclusion is that the actual productivity of
teak plantations has often been much lower than indicated
in yield tables; this is probably because sample plots are
likely to receive more management attention than field plantings
and because of statistical inadequacies of the samples.
Pandey (1996) has developed a model to predict the potential
productivity of teak plantations at the global or regional
level using climatic factors. Climatic variables explain 59
percent of the variance of the potential yield of teak plantations.
Relative humidity and annual rainfall were identified as the
most important climatic factors influencing the growth of
teak. Above certain upper limits, however (70 percent and
2,000 mm per year, respectively), increases in their values
result in successively less increase in the potential yield.
Teak is a fine example of the coppice species.
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