This calculator is useful in providing approximate weights for
species, but the user should be careful in how the product is used. Wood varies
considerably in weight per constant volume (density) on a regional level and at the local
level. That is, the weight of a piece of wood from one area or tree will differ from the
same species in the another area. The growth rate is the most significant factor in
determining density, with slower growing trees having a higher density (therefore greater
weight), than faster growing trees. This is due to the late wood cells (the dark ring seen
when a tree is cut) having thicker walls and being closer together than the early wood
(lighter wood between the rings). Where the board is cut from
the tree is another factor, the heartwood portion of the tree (the center portion, often
characterized by a change in colour) is composed of dead cells and will be lighter than
the sap wood, where the cells are still living. Wood that is cut from the portion of the
stem that still has live branches on it will be lighter due to hormones produced by the
foliage.
In different areas, genetics will play a factor in wood
density, along with the growing site (moisture and nutrient characteristics of the soil).
Where the tree grows on the hillside, eg south facing versus north facing slope, high
elevation versus low elevation, areas of heavy snowpack versus light snowpack, constant
winds versus sheltered locations all have an influence on the density of wood.