Check the story link below. Mark Weir got smited by a tree. I immediately thought of all the trail-builders out there.
http://reviews.mtbr.com/hot-news-mark-weir-breaks-pelvis-and-sacrum-in-freak-accident
I've seen first hand the energy stored in even a small tree. Put them under tension and you have a recipe for real problems. I know a lot of builders cut trees, but I have yet to meet one that is actually properly trained to do so (ie certified faller or utility arborist). Some of them are really good with their wood, but I've also seen some extremely dodgy saw work and some downright scary stumps. I've seen saws above the head, drinking and cutting, domino falling, and all manners of sins of cutting techniques (just in trailbuilding milieus). To be fair, I've seen a few level-headed folks wield a good saw, but most seem to be flying without a compass.
I figure this belongs in the trail-building section, but it is relevant to all riders. Wier wan't even building, just helping move a tree. Just because a tree is partially fallen or on the ground doesn't make it less dangerous. Partially fallen trees can be under tremendous tension, and may also have dislodged other nearby trees or branches.
Please, take the greatest care when cutting (or moving) wood. If you can, I highly recommend taking a danger tree assessment course, and receiving some professional saw training if you haven't already (but still want to use your saw out in the woods). Remembers anything over 6 inches in diameter (in the workplace) requires a pro to cut it, and even smaller trees than that can kill.
[HTML_REMOVED][HTML_REMOVED]Always have a cleared escape route from a tree you may be cutting
[HTML_REMOVED][HTML_REMOVED]Always have a spotter, first aid, and proper PPE
[HTML_REMOVED][HTML_REMOVED]Always control the scene and make sure nobody can enter the cutting (or falling) area
[HTML_REMOVED][HTML_REMOVED]Always inspect the tree (length of the stem, top, and branches) to detect weak sections, hung-up limbs, and broken tops (we call them widowmakers)
[HTML_REMOVED][HTML_REMOVED]Know that cutting (and falling) is highly technical, and can't be learned on the internet (even from windbags like me), and can't be learned (properly) from your buddies. There's no substituted from learning from a true faller.
[HTML_REMOVED][HTML_REMOVED]Most important, don't cut trees if you don't have to, or you're not qualified to do so.
Sorry for seizing the opportunity to preach, but it would suck so bad to see any trail builder get squashed (or cut). Such an accident would suck for the individual, and could also set off a whole new level of bureaucracy for everyone else that wants to be involved in trail-building. If you ever feel dodgy about a tree, don't be ashamed to flag it off until you can find someone more qualified to manage it with you or for you.
Wishing Weir a speedy recovery. Could have been a lot worse.