I looked up electron donors in Wikipedia and apparently those serve as reducing agents. I was confused how it would oxidize wood, so I looked up 'iron-catalyzed oxidation' and found an article (https://link.springer.com/article/10.1007/BF00351367) which claims oxidizing iron produces free radicals and hydrogen peroxide which subsequently eats the wood. I also came across https://en.wikipedia.org/wiki/Ferrous in my research....chemistry is complicated.