Genetically modified trees are not used.
No GMO trees are used in the U.S. hardwood sector. No commercial hardwood trees used in the hardwood sawmill industry are on any FAO lists of biotechnology in forestry: http://www.fao.org/docrep/008/ae574e/AE574E00.HTM.
Seneca Creek 2017 Assessment Section 7.8: There are no GM hardwood trees approved for commercial use and none in the mix of hardwood products produced or exported.
Seneca Creek 2017 Assessment Finding: 24: The FSC US national risk assessment process has affirmatively determined Low Risk of illegally harvested wood, wood harvested in violation of traditional and human rights, and wood from forests in which genetically modified trees are planted. [Section 11]