Man, this mechanic doesn't even have it's own page in the wiki
Yeah, I knew there was a kingdom lifeforce system... but there was not much info about it, all I could only find was that it effects things like if most travellers are living or undead. Checked the lifeforce section of you're link, and it pretty much says the same, nothing about loot item quality. If you're right, they really need to mention it.
And about the trees, they only increase 1 and 5 respectively so... whatever, you can see the current value with Dokuro's skill,
if for some reason increasing life force by a hundred or two doesn't solve it then your case may be a bug, i mean, it's such an obscure mechanic that the solution i'm giving you comes from my own testing.
Damn, I need hundreds and can only increase it by 6 a day? Wonder how much no wars adds to it. I found out about Dokuro last night... seems like you need to plunge the kingdom into the black and get the goblin killed... Kinda the opposite of what I wanted lol. I didn't know about the slime pearl though, so I'll check that. If it DOES affect loot item drops like you say, they really need to point that out in game somewhere.
Will give it a go until I raise it by 100 through the trees. Not that I need it for making money anymore, I found a better way to make swirlies now... 1 Minute days, mass stacked Zeal for a Fleeting Zeal farm, then turned into Zeal Potions... sell the level 1 potions and consume the level 2's and 3's lol.
Either way, thanks for the info, I will post again if upping lifeforce does affect drops.