Highlights
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- Effects of four tapping methods on anatomy traits and resin yield were evaluated.
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- Timing and spatial distribution of secretory structures were analysed.
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- Highest resin yield and axial canal frequency found for traditional upward tapping.
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- Strongest effects on xylem wood were detected one year after tapping.
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- Defence response induction was detected closer to wound and mainly in axial direction.
Abstract
External induction of resin secretion, based on the defence system of Pinus
trees, has been performed by humans since Classical times through
various methods. The socio-economic implication of this practice in
Spain and the expansion of the Chinese market justify a new approach to
tapping methodology and the effects of this activity on the tree. The
resin yield of 561 Pinus pinaster trees in a stand in central
Spain, tapped in 2012 using four different methods (mechanised or
traditional tool, upwards or downwards), was analysed. An anatomical
study was made of 13 trees (8 tapped and 5 controls) in another stand
13 km away with similar climate and soil conditions, tapped in 2011
using the same four methods. From each tapped tree, eight cores were
taken at different locations and varying distances from the tapping
wound. In each core, an analysis was made of growth ring, earlywood and
latewood width, and axial canal frequency, area, mean size and location
from one year before tapping to two years after (2010–2013). The highest
mean annual resin yield was found for traditional tool upward tapping,
which also induced the highest increase in axial canal frequency and
area. The lowest yield was found for mechanised tapping, which showed no
differences between the upward and downward directions. The strongest
induction of systemic induced responses in terms of resin canal
frequency and area was detected one year after tapping for upward
tapping. This suggests the involvement of signalling processes that
spread mainly upwards, and the importance of adaptive processes as a
defence to periodic insect attacks for this forest tree.
Keywords
- Resin ducts;
- Defence system;
- Induced resistance;
- Tapping;
- Non wood forest products;
- Disturbance
