RuneScape Classic Wiki
The main RuneScape Wiki has an article on: Yew Logs
The Old School RuneScape Wiki also has an article on Yew Logs.

Yew Logs are obtained by cutting a Yew tree with an axe. To cut down a yew tree a player will need at least 60 Woodcutting, and will receive 175 experience per log cut.

Yew trees were released with the Fletching skill and can be used to make yew shortbows and yew longbows, granting 67.5 Fletching experience per unstrung yew shortbow, and 75 experience per unstrung yew longbow.

Contrary to popular belief, yew logs can not be burned. Only normal logs are able to be burned for Firemaking experience.

Yew Logs can be certed to Yew logs certificates and uncerted by Chuck near north bank in East Ardougne.