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How much mass of a tree is from the soil, how much from the air?
A tree is made of water, minerals and CO2. Is there a rough estimate what percentage of its mass is lifted from the soil, and how much is added from the atmosphere? Jana |
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schreef
A tree is made of water, minerals and CO2. Is there a rough estimate what percentage of its mass is lifted from the soil, and how much is added from the atmosphere? *** A living tree will tend to consist mostly of water. However this will vary over the season. PvR |
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In message , P van
Rijckevorsel writes schreef A tree is made of water, minerals and CO2. Is there a rough estimate what percentage of its mass is lifted from the soil, and how much is added from the atmosphere? *** A living tree will tend to consist mostly of water. However this will vary over the season. PvR Does this also apply to heartwood? -- Stewart Robert Hinsley |
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As a plant physiologist, I would automatically answer this type of
question on a dry mass basis. The dry mass of a tree comes mainly from the air as CO2. Most of the plant dry matter is carbohydrate, with the general composition ratio of CH2O. The C and O come from CO2. The H comes from H2O. The atomic weights of C, O and H, are 12, 16 and 1, respectively. The molecular weight of CH2O is 30 so 2/30 x 100 =3D 6.7 % of its mass comes from H2O and 93.3 % from CO2. About 5% of the tree dry mass consists of mineral nutrients from the soil although this can be higher in some species. Thus, about 88% of a tree dry mass comes from CO2. On a fresh weight basis, the percentage of a tree derived from the soil will vary more widely and depend on the time of year, environmental conditions, tree age and type of tree. For example, the study below found new pine needles contained 85.8% water by weight in July and about 58% in December. http://dsp-psd.pwgsc.gc.ca/Collectio...-656-2002E.pdf Fromm et al. (2001) found Norway spruce sapwood contained 180% water and heartwood 50% water on a dry weight basis. English oak (Quercus robur) sapwood and heartwood both contained 75% water on a dry weight basis. On a fresh weight basis, English oak wood contained 43% water. Thus, in a leafless condition, there are some trees where less than 50% of the fresh weight came from the soil. Fromm, J=F6rg H., Irina Sautter, Dietmar Matthies, Johannes Kremer, Peter Schumacher, and Carl Ganter. 2001. Xylem Water Content and Wood Density in Spruce and Oak Trees Detected by High-Resolution Computed Tomography. Plant Physiol. 127: 416-425. http://www.plantphysiol.org/cgi/content/full/127/2/416 David R. Hershey |
#6
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In article 1120281346.0d0d82b38f8f99b5a132fc3aac0c8f05@teran ews, Sean Houtman wrote:
wrote in news:1120247575.530727.42810 : A tree is made of water, minerals and CO2. Is there a rough estimate what percentage of its mass is lifted from the soil, and how much is added from the atmosphere? You can do this on your own with a simple process. Weigh a tree, then burn it. All the CO2 and water will go away, leaving the stuff that came from the soil. You can weigh the ashes to get a rough estimate. It is not a precise measure, since some ash will be carried away as smoke, the nitrogen will also go, and the ashes will be mostly oxides instead of the salts they were taken in as. Well, yes. But don't forget that trees get most(?) of their water from the soil too [not sure about species in cloud forests and similar] and the questioner asked in terms of "lifted from the soil". Cheers, Phred. -- LID |
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