This tree is probably a douglas fir. The brighter zone of the annual rings is the early wood, built around in spring time/early summer. The cell structures are more voluminous. The darker annual ring zone is more dense, built later. Together they built one annual ring per year. If you count all the rings of a tree, you know the age. In the middle of this cross-section there are also twigs to be seen. The crack was maybe caused due to lack of care,or to much tension, or the stem dried to fast, or all together. The wider rings say that the tree had more space and light and/or better growth conditions. The narrow later rings show, that the stand where the tree grew got more dense. The tree had to compete with his colleagues for water, nourishment and light. The more even the annual rings are and the less twigs are to be seen, the higher the yield of the possible wood product usually could be; e.g. like high-class furniture. Annual rings can also be used to estimate climate conditions and historical analysis, e.g. going back in time more than 7.000 years ago.

For further information and facts, see - for example - the following links:

- Statistical age determination of tree rings | PLOS ONE

- Growth ring | Annual Rings, Cambium Layer & Xylem Cells | Britannica

- Annual Rings | Encyclopedia.com

- Dendrochronology - Wikipedia

- Wood - An introduction to its structure, properties, and uses (explainthatstuff.com)

- Properties of Wood - Composition, Physical, Mechanical and Thermal (vedantu.com)

- 🥇Wood properties - GREEMAP

- Wood Types, Characteristics and Identification Guide - Wood Assistant

last visit: 20. September 2023.