Don't tread on me!
Soil erosion is a monumental problem throughout our ravines and forests. Runoff from neighbouring streets and buildings tears down slopes, washing away dirt and debris as it goes. Human and animal traffic bullies the ground, scraping loose clumps and chunks. The loss and/or compaction of topsoil reduces opportunities for vegetation to establish itself, and it is these plant communities that are the front line of defense against erosion in the first place. It's a nasty, downward spiral.
The photo above was taken along the trail that passes the Roycroft wetland. The severe damage here has been heavily fostered by people (and their pets) who have chosen to ramble up and down the slope, year after year. A sign has been erected nearby that tries to educate visitors as to the consequences of their actions but, sadly, the message is ignored by many. If the damage continues, the trees will die.