Lumberjack is a skill you can buy using your woodworking guild points if I remember correctly you can buy it with 10,000 guild points, its very good like last night I crafted around 20 stacks of arrowwood lumber it cost me about 40k now each stack sells for around 10k thats a huge profit now if i didnt have this lumber jack i would have used at least 3 times the amount of crystals and since wind crystal a stack go for around 9-10k a stack it would have almost tripled my cost, so you can make easy money not fast but easy. Use this link to see what your guild is taking each day http://www.ffrecipe.com/guildPattern.php?lang=en
all lumber except ancient lumber can be either lumberjacked with wind crystal + 3 logs + bundling twine, or produced as a single with wind crystal + 1 log. ancient lumber can only be produced as a single, not lumberjacked