If trees were upside down, balanced precariously on their multitude of twigs and branches whilst the trunk grew mightily mighty high up, then we'd all die or at least get hurt enough so we die of our injuries. That's all I'm saying: they're but coiled springs, which could rebel against their coilage and flip upside down and kill us all. Give them credit for managing their anger and maintaining their youthful dignity throughout. And remember that woodpecker snot is pure oxygen, albeit in some bizarre glutinous form that doesn't turn to a gas, even at forest temperature.
Turn trees upside down and they'd burn. Like a fire I suppose: kindling, bigger branches, big ugly logs with 'Log' written on them. Dangerous. At least as it is now if you hold a match up to a tree (pygmy cannibalism reference?) the worst you'll get is a bit of singeing and vast swathes of Wisconsin burnt to a crisp. Wisconsin has sticky trees from all the cows and cheese. And sap. Sticky trees burn cos sap is pure glutinous hydrogen, trees rise (and also that rising sap phase that we all go through) cos of the hydrogen. Maple syrup is precluded by law from being sold with cigarette lighters for safety reasons (that semtex is just a time bomb waiting to go off). If hydrogen isn't highly flammable, this hydrogen is special magic tree hydrogen that is flammable and anyone who says otherwise must be persecuted and shunned for daring to question my authority.
The reason you never see a woodpecker with breathing difficulties, sucking down on an oxygen mask is the glutinous oxygen snot thing mentioned above. This mixes with the hydrogen sap when the woodpeckers do their eating thing, making water. Sticky trees burn when the right way up, non-sticky trees don't burn, but could if they were upside down. And the reason we can't tear open trees and drink their sweet sweet water instead of turning on a tap is cos of some nasty tree thing that's poisonous to humans or something. Bark, lichen, something like that. Chlorophyll maybe.
Points established thus far: woodpecker snot is oxygen, sap is hydrogen, sticky trees burn, non-sticky trees don't, but would if upside down. Prey: allow me to elucidate on the final point further (more ego, Igor). When upside down all the sap would rise to the trunk and roots, where woodpeckers would add their hydrogenous snot when rooting around for worms. Water forms here, leaving the previously watery leaves and twigs all sticky and ready to form a base of hot coals on which the damp tree trunk can burn like rats in cages later. It all makes sense really, and all I'm saying is that it's a good thing trees (non-Wisconsin trees... well just good ol' English oaks) are up the right way or they'd all burn us. And I suppose in any form of wind they'd blow over and crush our dogs. Or our children if we were foolish enough to let them go play in the highly flammable and precariously balanced forests, which we would cos it gets them out of the house, eh parents?