## Greening Marrickville

Marrickville is one of the most densely populated areas of Sydney.

It has only a small amount of public open space and lacks a substantial tree canopy.

The Greens have a vision of a greener Marrickville, literally. We want to increase the number of trees, or tree canopy in our area.

Our policy goals area:

- Increase the number of street trees planted
- Ensure street trees speicies are of a good size and preferably native
- Protect existing street trees from removal by council or by Electricity Australia
- Increase the number of plantings in street treatments such as curb blisters and round-a-bouts
- Encourage residents to plant their verges with native ground covers and shrubs instead of grass
- Increase the number of ‘bush pockets’ in disused open areas
- Increase the number of trees in some of our parks, such as Sydenham Green

Trees serve important purposes because they:

- provide oxygen and absorb carbon dioxide
- provide shade and reduce the ‘urban heat island’ effect
- reduce run off from storms
- promote rainfall through respiration
- provide habitat for birds and animals
- beautify the environment
- increase property values

On council we are working to green the Inner West. We have started two online galleries:

1) Good street treatments – examples of good street treatments.

2) Areas that need trees – streets in the Marrickville local government area that need trees planted.

If you would like to send us your photographs of good street treatments, or an area you think needs a tree email: phillips.max@gmail.com (include the location of the photo).

## HOW TO MEASURE HOW MUCH CO2 TREES STORE

How to calculate the amount of CO2 sequestered in a tree per year

We at Trees for the Future estimate that our agroforestry trees, planted in tropical

climates, will sequester atmospheric carbon dioxide at an average of 50 pounds of carbon

dioxide per tree per year.

The rate of carbon sequestration depends on the growth characteristics of the tree species,

the conditions for growth where the tree is planted, and the density of the tree’s wood. It

is greatest in the younger stages of tree growth, between 20 to 50 years.1 Further

complicating the issue is the fact that far less research has been done on tropical tree

species as compared to temperate tree species.

Nevertheless, we can roughly estimate the amount of CO2 sequestered in a given tree,

and if we divide by the tree’s age, get a yearly sequestration rate.

We got this process from two educational websites who had conceived it as a learning

activity for their students. 2 This is the process:

1. Determine the total (green) weight of the tree.

2. Determine the dry weight of the tree.

3. Determine the weight of carbon in the tree.

4. Determine the weight of carbon dioxide sequestered in the tree

5. Determine the weight of CO2 sequestered in the tree per year

*Determine the total (green) weight of the tree*

Based on tree species in the Southeast United States, the algorithm to calculate the weight

of a tree is: 3

W = Above-ground weight of the tree in pounds

D = Diameter of the trunk in inches

H = Height of the tree in feet

For trees with D < 11:

W = 0.25D2H

For trees with D >= 11:

W = 0.15D2H

Depending on the species, the coefficient (e.g. 0.25) could change, and the variables D2

and H could be raised to exponents just above or below 1. However, these two equations

could be seen as an “average” of all the species’ equations.

The root system weighs about 20% as much as the above-ground weight of the tree.

Therefore, to determine the total green weight of the tree, multiply the above-ground

weight of the tree by 120%.

*Determine the dry weight of the tree*

This is based on an extension publication from the University of Nebraska.4 This

publication has a table with average weights for one cord of wood for different temperate

tree species. Taking all species in the table into account, the average tree is 72.5% dry

matter and 27.5% moisture.

Therefore, to determine the dry weight of the tree, multiply the weight of the tree by

72.5%.

Determine the weight of carbon in the tree

The average carbon content is generally 50% of the tree’s total volume.5 Therefore, to

determine the weight of carbon in the tree, multiply the dry weight of the tree by 50%.

Determine the weight of carbon dioxide sequestered in the tree

CO2 is composed of one molecule of Carbon and 2 molecules of Oxygen.

The atomic weight of Carbon is 12.001115.

The atomic weight of Oxygen is 15.9994.

The weight of CO2 is C+2*O=43.999915.

The ratio of CO2 to C is 43.999915/12.001115=3.6663.

Therefore, to determine the weight of carbon dioxide sequestered in the tree, multiply the

weight of carbon in the tree by 3.6663.6

**Determine the weight of CO2 sequestered in the tree per year**

Divide the weight of carbon dioxide sequestered in the tree by the age of the tree. Et

voila!

EXAMPLES

Estimated growth rates and sizes of agroforestry trees were taken from the World

Agroforestry Centre’s “Agroforestree Database”7:

Let’s see how much a Calliandra calothyrsus might sequester in a year. A 10-year-old

Calliandra would probably grow about 15 feet tall with a trunk about 8 inches in

diameter. Therefore:

W = 0.25D2H = 0.25(82)(15) = 240 lbs. green weight above ground.

240 lbs. * 120% = 288 lbs. green weight (roots included)

288 lbs. * 72.5% = 208.8 lbs. dry weight

208.8 lbs. * 50% = 104.4 lbs. carbon

104.4 lbs * 3.6663 = 382.8 lbs. CO2 sequestered

382.8 lbs / 10 years = 38.3 lbs. CO2 sequestered per year

Or consider a 10-year-old Grevillia robusta, 45 feet tall with a trunk 6 inches in diameter.

Using the same calculations as above, the amount of CO2 sequestered would be 64.6 lbs.

per year.

Or a newly-planted Acacia angustissima, 2.5 years old, 15 feet tall with a trunk 3 inches

in diameter: 21.5 lbs. of CO2 sequestered per year.

Or an Albizzia lebbek, 15 years old, 30 feet tall, with a 12 inch trunk: 68.9 lbs. of CO2

sequestered per year.

*Other methods*

Another way to estimate the amount of CO2 sequestered by a tree in a year is to estimate

the amount sequestered in a hectare per year, and divide that amount by the number of

trees per hectare. Scanning around on the Internet, it seems that the number of trees per

hectare (in agroforestry and/or industrial plantations) ranges from under 500 to over

2,000.

According to Myers and Goreau, tropical tree plantations of pine and eucalyptus can

sequester an average of 10 tons of carbon per hectare per year. 8 Therefore, the

plantation can sequester an average of 20,000 lbs * 3.6663 = 73,326 lbs CO2/ha/year, or,

taking an average of 1,000 trees per hectare, 73.326 lbs CO2/tree/year.

Of course, we heavily discourage the planting of pine and/or eucalyptus in our

agroforestry systems. Our trees may not grow as fast or as straight as eucalyptus, but

they are not invasive, and they do not destroy the water table and the soil!

Disclaimer

This research and methodology is based on research papers, university publications, and

other information freely available on the Internet. As we stated before, it is difficult to

calculate the amount of carbon dioxide sequestered per tree per year due to the

complexity of the variables involved, as well as the lack of research on tropical tree

species. If you have any information that could further refine or enhance our

calculations, please let us know at info@treesftf.org. Thanks and happy tree planting!

1 http://www.rcfa-cfan.org/english/issues.13.html

2 The National Computational Science Leadership Program

http://www.ncsec.org/cadre2/team18_2/students/purpose.html and

The Shodor Education Foundation

http://www.shodor.org/succeedhi/succeedhi/weightree/teacher/activities.html

3 “Total-Tree Weight, Stem Weight, and Volume Tables for Hardwood Species in the Southeast,”

Alexander Clark III, Joseph R. Saucier, and W. Henry McNab, Research Division, Georgia Forestry

Commission, January 1986.

http://www.forestdisturbance.net/publications/GF%20RP60-Clark.pdf

4 “Heating With Wood: Producing, Harvesting and Processing Firewood,” Scott DeWald, Scott Josiah, and

Becky Erdkamp, University of Nebraska – Lincoln Extension, Institute of Agriculture and Natural

Resources, March 2005.

http://www.ianrpubs.unl.edu/epublic/live/g1554/build/g1554.pdf

5 “Carbon Storage and Accumulation in United States Forest Ecosystems, General Technical Report W0-

59,” Richard A. Birdsey, United States Department of Agriculture Forest Service, Northeastern Forest

Experiment Station, Radnor, PA, August 1992.

http://www.ilea.org/birdsey/fcarbon_index.html#toc

6 http://www.ncsec.org/cadre2/team18_2/students/helpCalcCO2.htm

7 http://www.worldagroforestrycentre.org/Sites/TreeDBS/aft.asp

8 “Tropical Forests and the Greenhouse Effect: A Management Response,” Norman Myers and Thomas J.

Goreau, Discovery Bay Marine Laboratory, University of the West Indies, Discovery Bay, Jamaica, 1991.

http://www.ciesin.columbia.edu/docs/002-163/002-163.html

The take-up of solar and the increasing move towards utilising backyards for growing food is in direct conflict with large trees. I would like to see tree removal/replacement policies amended to take these shifts in trends into account. Shadowing has a detrimental effect on the output of solar panels and also limits the use of backyards.