What gives trees its huge mass considering carbon dioxide water and sunlight are not as heavy as the tree?

Answer 1

Trees absorb Carbon Dioxide (CO2), remove the carbon and store it, and release the oxygen. Almost half the mass of a tree is carbon.

Trees get most of their mass from water, but they do process a prodigious amount of carbon dioxide over their lifetimes.

If we look at this sugar from a mass standpoint, we see that a large fraction of it is due to the carbon. The fact that carbon has an Atomic Mass of 12, hydrogen has an atomic mass of 1, and oxygen has an atomic mass of 16 means that 72/180 = 40% of the mass of the sugar molecule comes from carbon. Taking into account the other types of molecules that are found in a tree (proteins, lipids, etc.), we find that about 45% of the dry mass (not including the water) of a tree comes from carbon. In other words, a 100 kilogram log of a tree that has been completely dried contains about 45 kilograms of stored carbon.

The article further finds that those 45 kg of stored carbon are produced from 165 kg of carbon dioxide, meaning that 120 kg of oxygen are produced. According to Wolfram Alpha, these equate to 89,600 L of carbon dioxide and 84,000 L of oxygen!

Incidentally, you're following in promising footsteps asking this question. In the 17th century, Jan Baptist Van Helmont was a careful observer of nature; it can be inferred that from his analysis of data gathered in his experiments suggested he had a concept of the conservation of mass. He performed an experiment to determine where plants get their mass. He grew a willow tree and measured the amount of soil, the weight of the tree and the water he added. After five years the plant had gained about 164 pounds. Since the amount of soil was basically the same as it had been when he started his experiment, he deduced that the tree's weight gain had come from water. Since it had received nothing but water and the soil weighed practically the same as at the beginning, he argued that the increased weight of wood, bark and roots had been formed from water alone. However, this "deduction" is incomplete, as a large proportion of the mass of the tree comes from atmospheric carbon dioxide, which, in conjunction with water, is turned into carbohydrates via photosynthesis.

Answer 2

The mass of trees mainly comes from carbon absorbed from the air during photosynthesis. This carbon is used to build the structure of the tree, including cellulose and lignin in the trunk, branches, and leaves. The process of photosynthesis transforms carbon dioxide and water into glucose, which is then used as an essential building block for tree growth.