I saw in a permaculture video which stated that pollarding a tree causes the roots to also be pruned. Is that true? After a quick search, I couldn’t seem to find anything on the web from a publication to support this idea.
The category of the video was the first clue that something was amiss. Permaculture is a marketing term. For folks that believe otherwise, I refer you to the 3rd law of thermodynamics.
I looked up the 3rd law of thermodynamics. Not sure what you’re referring to. Can you explain? I’m open to all ideas and am just trying to learn more.
Doesn’t make any sense why that would occur. Perhaps root growth would be slightly reduced in accord with reduced above ground growth? But to say root pruning occurs seems disingenuous at best.
Not sure if the type of tree matters, but he was referring to a nitrogen fixing tree.
According to this academic article I found my answer: http://www.academia.edu/1418076/Nitrogen-fixing_trees_and_nitrogen_fixation_in_sustainable_agriculture_Research_challenges
What happens to Nz uptake when NFT are pollarded
or heavily pruned under different schedules,
and how does this compare with non-pnmed trees
of the same species with similar leaf biomass?
The field is open to much speculation. The first
guess would be that after pruning there is less
photosynthetic activity, less nodule formation and
increased nodule mortality. This may be followed
by an increase of nodules (Russo, 1986). However,
there also are advantages for the pnmed tree.
Pollarding is a rejuvenation process, and new
branches are formed quickly with typical juvenile
leaves. How does this affect new root and nodule
production? Soil was removed carefully from the
roots of 20-30 y-old Erythrinu poeppigiunu trees
that had been used to shade toffee. These trees had
been pollarded twice a year and had four to seven
large radial and superficial roots, often over 10 m
long. They continued to serve irrespective of pruning
the shoots. Many smal1 roots and nodules had
died, but new rootlets and nodules formed rapidly.
In comparing the nitrogen added to the soil from
pollarded VS non-pollarded trees, the dying rootlets
add nitrogen and may add channels to decrease
compaction and provide passage for new roots.
Soils compacted by livestock in pastures derived
from forests constitute a major problem in the
humid tropics. Planting and pollarding of NFT
may become an effective technique for “decompacting”
and revitalizing these degraded and often
abandoned lands.
My opinion would be that cutting back the top severely would “prune” back root hairs and possibly small roots. But it won’t cause the larger roots to die. I won’t call that a root pruning. But lets face it this is a difficult subject to study.
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Here’s paraphrasing of the 3 laws by poet Alan Ginsberg, in terms of someone playing a game:
- You can’t win. (consequence of first law of thermodynamics)
- You can’t break even. (consequence of second law of thermodynamics)
- You can’t even get out of the game. (consequence of third law of thermodynamics)
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Severe pruning causes a percentage of roots to die so I guess you can call it pruning even though it isn’t. Vegetative wood sends more energy to the roots than fruiting wood, so severe pruning removing all fruiting wood can also lead to greater root vigor in mature trees. It would depend on the species and even the variety within a species how dramatic the affect would be. For instance, an apple that is a tip bearer on last years growth would not send as much energy to the roots as a variety that only flowers on 2 or 3 year wood. It takes a great deal of energy to form flower buds for next year’s fruit. Very vigorous growers would obviously send more energy to the roots as well.
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