The chemical constituents of pod of Gleditsia sinensis Lam. have been studied.The saponin, fibrin, half fibrin, xylogen and proteins of it have been mensurated.
Yeah, the cells, if you think of the walls of the cells, they make the tree strong and there are a couple of chemicals that make up these walls, cellulose and lignin.
Well the fungi are important, even though they make something like 5% of the living things in the rumen, they can breakdown specific bonds between the lignin inside the cellulose.
All of the bonds in the molecules of cellulose and lignin that make up the wood contain energy, and some of them could be broken, releasing that energy.