Editing Conifer (section)

===Tree ring structure===
[[File:Report on the relation of railroads to forest supplies and forestry - together with appendices on the structure of some timber ties, their behavior, and the cause of their decay in the road bed, on (14755970324).jpg|thumb|A thin transverse section showing the internal structure of conifer wood]]

[[Dendrochronology#Growth rings|Tree rings]] are records of the [[wikt:influence|influence]] of [[Ecology#Physical environments|environmental]] conditions, their anatomical characteristics record growth rate changes produced by these changing conditions. The microscopic [[structure]] of conifer wood consists of two types of [[cell (biology)|cells]]: '''parenchyma''', which have an oval or polyhedral shape with approximately identical dimensions in three directions, and strongly elongated tracheids. '''Tracheids''' make up more than 90% of timber volume. The tracheids of earlywood formed at the beginning of a [[growing season]] have large radial sizes and smaller, thinner [[cell wall]]s. Then, the first tracheids of the transition zone are formed, where the radial size of cells and the thickness of their cell walls changes considerably. Finally, latewood tracheids are formed, with small radial sizes and greater cell wall thickness. This is the basic pattern of the internal cell structure of conifer tree rings.<ref name="Ledig-1982">{{cite journal |last1=Ledig |first1=F. Thomas |last2=Porterfield |first2=Richard L. |date=1982 |title=Tree Improvement in Western Conifers: Economic Aspects |journal=Journal of Forestry |volume=80 |issue=10 |pages=653–657 |doi=10.1093/jof/80.10.653 |osti=5675533 }}</ref>