Cost basis for timber is usually zero.
For a discussion on Timber Basis, see https://www.extension.purdue.edu/extmedia/FNR/FNR_FAQ_2.pdf
Additional References:http://www.timbertax.org/developments/Federal%20Income%20Tax%20on%20Timber-%20A%20Quick%20Guide%20fo...
https://www.fs.fed.us/spf/coop/library/taxpubfaqs.pdf
https://ttlc.intuit.com/questions/2894323-where-do-i-enter-a-1099-s (1099-S for timber)
https://ttlc.intuit.com/community/entering-importing/help/where-do-i-enter-income-from-a-timber-sale...(TT FAQ timber)
