They will leap up and strike you on the knee when you least expect it. But seriously, the rocks here are covered with algae and are especially slippery when they are wet, which is most of the time. The last accident was potentially the worst because the person was working alone and slipped between boulders on a river in the El Verde Research Area and was unable to move. Fortunately, they were able to pull their radio from their backpack and summon help. If you are walking or working in rocky areas and are prone to slipping and falling, consider wearing lightweight gloves - they really help when grabbing trees and rocks to maintain your balance.
Body armor is another option.
Many types of knee and shin pads have been tried here, but the ones that work best are made for ice hockey and volleyball. You can also buy felt soles and superglue these to your own shoes. USDA Forest Service regulations say that hard-hats should be worn in the field, and there are plenty available for your use. Although branch falls can occur at any time, they are most frequent when windy conditions follow rains. Trees seem to fall with unnerving frequency during droughts.