TEAK PLANTATIONS IN NILAMBUR - Kerala Forest Research Institute

During the period 1967 to 1981, the mean total yield from 251 operations
covering 8342 ha was 165m 3 ha -1 and MAI at 56 years was 2.954m 3 ha -1 year -1 .
During the period 1982-94 the mean total yield from 117 operations covering
4035 ha was 105m 3 and MAI at 51 years was 2.064 m 3 ha -1 year -1 . For
comparison of the productivity between the two periods it is not enough to
compare the total yield as the rotation ages are different. Therefore the MAI
for the two periods is used for the comparison. The productivity, as observed
from the MAI, is higher in the period 1967-81 than in the subsequent period
1982-94. It may be noted that the variability in yield is more pronounced
during the period 1982-94 than during 1967-1981.
During the period 1967-1994, pooling the data from 372 plantations covering
12536 ha, the mean age of final felling became 53 years. The MAI at 53 years
was found to be 2.854m 3 ha -1 yr -1 which is the mean productivity of teak
plantations in Nilambur Divisions. This estimated mean yield is used in the
pro fitability analysis.
In Tables 3.1 to 3.3, the maximum and minimum yields in each type of work
are shown. The minimum and maximum are extreme values which are not
used for further analysis. For this, the yields representing the lowest and
highest ten percent of area were estimated when yields were arranged in the
ascending order. These are the mean yields in the lowest decile and the
highest decile of the entire data. The yields in the lowest decile and highest
decile are hereafter called 'low yield' and 'high yield' and they are used later in
the profitability analysis. Table 3.4 shows the estimates of mean yields
representing the entire data and those in the lowest and highest deciles. The
estimated MAI in the lowest decile is 0.973 m 3 ha -1 yr -1 and that in the highest
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