Theft/Fraud
Digging plants especially any that have specific habitat needs, making
successful transplantation next to impossible, such as lady slipper
orchids as well being typical of most rare, threatened, and/or endangered
species. This is an unconscionable act especially if the area has been set aside to preserve these plants. What is worse the offender often claims to be an "environmentalist" or some other lame justification for repeated offenses and the punishment if any is lax.
"Accidentally" logging on the wrong property is not a credible excuse
because GPS, maps, and/or aerial photos could easily be used to the verify location.
Claiming that resin glands on short-leaf pine tree bark was caused by
pine beetles burrowing into the tree, therefore, the trees need to be
"saved" by clear cutting the entire stand, sometime even including the
hardwoods. Real holes caused by pine beetles are about as large or
larger than a pencil lead, and a legitimate pine beetle mitigation does
not remove the trees due to the risk of spreading the infestation to
other stands.
Littering
Walk any road or step ashore on any remote lake shore (especially if upwind of the prevailing breeze or the left bank relative to any downstream current) and see how "It's just a little bit of litter," really adds up and to where "It all just gets washed away." Hopefully everybody "Giving the county jail litter crew something to do" will get a chance to join them for a week or so and become reformed litter bugs, but annual convictions are usually only in the single digits per county. A judge south of here threw out all the littering tickets given for cigarette butts despite some of the gutters in that city being filled over six inches deep with litter mostly in the form of cigarette butts. He should be giving them all an additional attempted arson charge whenever a burn ban is in effect, or a reckless driving charge if they claim the butt was put out first. It wouldn't have even made a dent if everybody ticketed had been ordered to pick up the number of butts resulting from $500 worth of cigarettes estimated to be only 5 plastic grocery bags full at the most, therefore, the lesser of the number of butts from $500 in tobacco tax, or $500 in community service hours at minimum wage after taxes would be equivalent to the maximum $500 fine for littering.
Fire rings are not magic garbage cans where everything goes away especially metal and plastic including paper with such linings. This just melts or worse converts to a toxic compound.
Nobody wants to see toilet paper "flowers" and disposable hygiene products including diapers near a hiking trail of campsite when they could have been packed out, much less stepping in something that should have been buried a couple hundred feet away.
Vandalism/Graffiti
Cutting trees, usually done on public property by adjacent landowners, because a view is visible a short walk away but not from their living room window.
Carving/drawing on trees or rocks, especially in rock shelters and wild caves where Indian petroglyphs and speleothems have respectively been destroyed.
Out of bounds campfires can leave marks that are just as permanent, which is why regulations limiting the use of campfires should be obeyed.