Field evaluation of stump and root trainer grown teak(Tectona grandish L.f.) plantations
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Date
2019
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Department of Silviculture & Agroforestry, College of Forestry , Vellanikkara
Abstract
Teak (Tectona grandis L.f.) stands out to be the most popular commercialtimber species in the tropics by virtue of its matchless combination of properties.
Over a century, root- shoot cutting (stump) has been the common nursery productiontechnology for teak across the world. However, the recent decade has seen
unprecedented decline in the productivity of teak plantations which could be
attributed to diverse reasons. In this context, the efficiency of the stump based
planting method for teak hence assume close scrutiny by virtue of the limitation in the
root spread and consequent belowground resource acquisition.
In this backdrop, a field study entitled “Field evaluation of stump and root
trainer grown teak (Tectona grandis L.f.) plantations” was conducted on teak
plantations established at Karakkad, Kalady range, Malayattoor forest division,
Kerala during 2017-18, to evaluate the influence of planting material viz. stump and
root trainer on growth aspects, soil physio-chemical properties and root distribution
separately in five and seven-year-old teak plantations. The teak plantations selected
for study included; five-year-old (2012 establishment) stump and root trainer grown
stands at 3x3 m spacing, seven-year-old (2010 establishment) stump and root trainer
based stands at 2x2 m initial spacing. Attempt were also made to study the effect of
planting spacing on the growth of teak that was raised from root trainers and managed
separately at 2x2 and 3x3 m spacing. Nine random plots of size 20x20 m were
demarcated for each of the treatments such that there were 45 experimental plots for
observation. Altogether there were three treatment combinations for comparison viz.
stump vs root trainer at 3x3 m spacing and five-year-old; stump vs root trainer at 2x2
m spacing and seven-year-old; five-year-old root trainer based teak stands at 3x3 m
vs at 2x2 m spacing. Each treatment combinations were analyzed separately with
independent t- test.
Biometric observations on teak growth showed considerable difference with
variable planting material and spacing. Root trainer grown teak stands showed better
performance in total tree height (6.68 m at seven-years of age), DBH (9.04 cm at
seven-years of age), and mean tree volume (0.031 m3 at seven-years of age) as
compared to stump origin stand both at five and seven-years of stand ages. The basal
area and bole height showed marginal improvement in root trainer grown stand at
five-years of age. Initial spacing showed only marginal influence on total height and
bole height with an advantage for stands at 2x2 m spacing as compared to 3x3 m
spaced stands. However, DBH, basal area and volume showed discernible
improvement in the stands at 3x3 m spacing. Crown diameter showed a nominal
increase in the root trainer grown stand than stump grown stand at both ages.
However, spacing had great influence on the crown diameter with more spread
(2.7 m) by widely spaced stands (3x3 m). Stand LAI also was better for root trainer
stand while spacing had poor influence on LAI. Persistence of stem axis and
straightness of stem showed limited advantage for stump grown teak origin stand.
Also closely spaced teak stands (2x2 m) developed from root trainer stands showed
slightly better performance than teak at wider spacing (3x3 m).
Attempts to analyze the influence of planting material and spacing on plant
leaf nitrogen and soil physio-chemical properties suggested that plant leaf nitrogen
concentration was modestly better for root trainer grown trees than stump grown
trees. However effect of spacing indicated that widely spaced trees (3x3m) showing
significantly higher nitrogen up take than narrow spaced trees. Soil physical and
chemical properties were found to be less influenced by the planting material.
However, all teak stands irrespective of planting material showed considerable
improvement in soil organic carbon and nitrogen concentration and reduction in soil
bulk density as compared with respective treeless open plots. Also there was
consistent reduction in carbon content and nitrogen with increase in soil depth up to
one meter soil depth. The average soil carbon concentration values were 1.15 % and
1.55 % for the root trainer and stump grown teak stands at seven-years of stand age.
The corresponding soil carbon stocks were 24.60 Mg ha-1 and 32.85 Mg ha-1 for teak
stands at seven-years of stand age.
Investigations on root distribution among stump and root trainer grown teak
trees revealed obvious advantage in root spread and root intensity for root trainer
raised teak stands. Teak trees grown from stump had smaller roots confined to the
base of the tree at shallow depths which drastically reduced with increase in lateral
distance of soil depth. The presence of prominent multiple tap root systems could be
the reason for the high root spread observed with root trainer based teak trees. The
trends were the same for small, medium and larger root intensity. Yet another
noteworthy observation was that teak trees at closer spacing showed reduction of root
spread and restricted the root system at proximal lateral distance while widely spaced
trees showed wider root distribution.
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174601