I read that it takes %26quot;24 trees to produce one ton of paper%26quot;, is this true, if so why? My back of the envelope calculations made me question this stat.:-

density of spruce wood = 450 kg/cm^3 (http://www.simetric.co.uk/si_wood.htm)
volume of a spruce tree = 300 cm^3 (http://en.wikipedia.org/wiki/Sitka_Spruc...
mass= 135,000 Kg, let%26#039;s assume 100 tons.

24 trees equal 2400 tons of material

Hence, 0.04 % effecient ! That%26#039;s an incredible wastage, surely this can not be correct...

Additional Details

1 month ago

m^3 see the reference...

1 month ago

Sorry about the units - all should be in m^3! The second link was from wiki on sikta spruce unfortunately yahoo answers abbrev. long links, hence the dead link sorry! I will try again:-

http://wikipedia.org/wiki/Sitka_Spruce

The link (if the above works) states that the wood volume for spruces is %26lt; 337 m^3.

0.45 m^3 seems a little small to me, that%26#039;s about the size of an oven...? But perhaps that is a more realistic number than the quoted super sized trees!

%26quot;Remember also wood has a higher water concentration than paper.%26quot; - that is an intersting point i had not thought about.

1 month ago

Thank you for your answers, I will leave this to a vote.

To me that the stat. might be a lot clearer (though not as catchy) if it said it takes 3-5 tons of hardwood/softwood to make 1 ton of paper. The number of trees to me seems largely irrelevant, the yield/wastage is the important part, it highlights how much extra would be required for sustainability (when offset against recycling). 16% 7 Votes

lol

Paper pulp today comes primarily from farmed Aspen trees. They grow fast and easy. They are harvested every 5-6 years. They use 100% of the tree. They are replanted they same day they are harvested. 20% 9 Votes

The full sentence in the article you read states %26quot;It has been estimated that based on a mixture of softwoods and hardwoods 12 meters (40 ft) tall and 15-20 centimeters (6-8 in) in diameter, it would take an average of 24 trees to produce 0.9 tonne (1 ton) of printing and writing paper, using the kraft process (chemical pulping).%26quot;

So your answer is right there. They tell you the size of the trees they are talking about - Each tree would have a volume of about a quarter of a cubic metre and would weight about 120kgs. So 24 of them would weight a little under 3 tons.

Given that only the wood fibres are used in paper making and all the water, bark and soluble sugars and starches are discarded, the 33% yield sounds quite reasonable to me. 27% 12 Votes