Dear
Dorothy Dioxide:
Can trees really produce Oxygen and help to lower Carbon
Dioxide
(CO2) levels in the atmosphere?
Sandra S, 10yrs, Yea
Dear Sandra,
Did you know? – trees can make their own food. They
use the energy in sunlight to convert carbon dioxide and
water to simple sugars and oxygen. This process (one of the
ways trees ‘breathe’) called photosynthesis,
occurs within a plant’s leaves. Unlike people, trees
love to take in carbon dioxide (CO2) through their tiny leaf
pores, whereas water is usually transported to the leaves
from the roots. The by-product of Photosynthesis is oxygen
(O2) released at night by plants (through their tiny leaf
pores), which people must ‘breathe’ to live.
Trees use CO2 to store carbon (the woody structure) necessary
to support the plant as it grows.
Take Care of Trees, Doxy
Dear Dot
Could you please tell me how many trees I need to plant
to justify a trip to Cambodia and back for three passengers?
Travel Bug, Limestone
Dear Travel Bug,
The sequestration of carbon dioxide (CO2) is based not on
how many trees you plant, but on what area of trees you plant,
what species you plant and where you plant them, how you
manage them, and over what period of time you are going to
count the sequestration.
A trip from Melbourne to Phnom Penh, with a transit in Singapore,
would cover a total of 14,400 km.
The CO2-e emission rate (which allows for 2 take-offs and
landings each way, and which covers the non-CO2 emissions
at high altitude which are also potent greenhouse gases)
would be about 0.42 kg CO2-e (carbon dioxide equivalent)
per passenger kilometre. This would give a total of 5.9 tonnes
of CO2-e emitted for the return journey for each person.
This assumes that each person flies economy class. If they
fly business class, add an extra 50% to the above figure
to account for the extra space taken up by business class
passengers!
1) If
the average CO2-e uptake for mixed species native trees
is 0.268 tonnes
per tree over its lifetime (www.greenfleet.com.au), then
22 trees would need to planted in
117 sq metres (Greenfleet uses a spacing of approximately
3m x 3m when
planting trees) to offset one return flight to Cambodia.
However,
2) If the trees being planted are destined for eventual harvesting
and replanting over a 20-year rotation, and all the emissions
are to be sequestered in one average year of growth in these
trees, then a total of 0.30 hectares must be set aside for
that year to absorb sufficient CO2 to offset the emissions
from the flight. At an average cost of about $12 per tonne
of CO2, the cost of the offset for one economy class return
flight from Melbourne to Phnom Penh would be about $70. For
more information contact local business: www.TreeSmart.com.au
Happy Carbon-neutral Travelling! Dot
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