Holy c#ap... 12" alder, probably S-shaped from hunting the light, late May as it seems to me from the photo(?). Backleaning rotten punk is better to deal with at times. From my experience around here, alders are worst during about 6-8 weeks after first leaves emerge that year. The younger the tree and the faster the transition from winter to vegetation season, the worse. Shalow face, nips under the hinge from sides, coos, stronger saw than needed for the size with kinda race grinded chain and prayer/helluva cussing, whatever comes handy at the moment-that´s what I´ve learned.
Or use Skeans advice-he got it sorted pretty damn well, his recipe is also easier on gas bill
Just remember that "escape patch preparation" is more important this style
Also the block face-at least some parts of the year. I´ve seen "reversed chair" with it-slight lean (like 3 ft for 70´, 11" tree), taking no chances and blockfacing it to the lean-and albeit he didn´t cut up into the trunk over the top gunning cut, a crak right from the plunge cut went up some 20´...