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Friday, December 09, 2005

Not just another Aucklander?

The sad naked hills of Motutapu
Photo from trust website
If you are:

(1) an Aucklander and
(2) are getting sick of reading the depressing stuff on this site and
(3) you would like to make a difference, then

Why not try volunteering for the Motutapu Restoration Trust? I have gone over for a day of volunteering three times so far, and have thoroughly enjoyed it. The trust has planted over 300,000 seedlings, covering 65 hectares of regenerating forest, since it was established in February 1994. A hectare of land can be planted with about 4500-6000 seedlings, which will eventually thin out to a mature patch of forest containing about 1000-1200 mature trees. To plant the whole island will take about 7.9 million seedlings, or about 430 volunteer years. I guess at some point the forest might start replanting itself though... The trust plans to plant 30,000 seedlings next year, amounting to 600 person-days of volunteering. You can be one of those person-days!

Based on standard calculations the regenerating forest on Motutapu is sequestering about 1.5-4.5 tons of carbon (5.5-16.5 tons of CO2) per hectare per year. Counting all 65 hectares, this is will neutralize about 730 tons of CO2 emissions).

A 1.4 litre car travelling 20,000 km per year will, on average, produce 3.5 tonnes of carbon dioxide (CO2). This mean that the current regenerating forest on Motutapu neutralizes the greenhouse emissions of about 210 cars on Auckland's roads. If the whole island was planted in regenerating forests it would neutralize the emissions of about 5000 cars on the roads.

Not bad, but still leaves a lot to be done... for instance you could drive less and conserve electricity :-)

Now lets finish the calculation. New Zealand has about 3.6 million cars. From the above calculations you need about 0.32 hectares of regenerating forest for each and every car. That means we need about 1.15 million hectares of regenerating forests to neutralize the emissions of all the cars in New Zealand. That works out to only about 4.3% of the total land mass (268,021 sq km) of New Zealand. Totally reasonable. What we need is for scientists to work out a super-efficient automated way to plant regenerating forests. Because right now volunteer hours are the bottleneck!!

Assumptions for calculation of 7.9 million seedlings and 430 person years:
* Each hectare is planted with 5250 seedlings
* Each volunteer plants 50 seedlings a day
* Motutapu Island is 1509 hectares

* 1 metric ton of carbon equivalent is 3.67 metric tons of CO2


  • At 10:49 AM, Blogger dc_red said…

    Great stuff ... this country has too many bare-ass (or, as you put it more eloquently, "sad") paddocks, with frequently not a single tree in site. We simply don't need that much sheep pasture ... I guess there is the "regenerating" gorse in many places though ... I wonder how much carbon that absorbs. On Mt Cargill in Dunedin the gorse is old enough to have formed trees, complete with a canopy layer.

  • At 7:22 PM, Blogger Xavier said…

    And how much CH4 does said area of forest produce? :P


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