I must admit I have been rather mischevious in the past and have seed bombed patches of boring grass in the city or in areas where you feel a bit of diversity and wildlife would be preferred over manicured lawns... I have also heard of people seed bombing hemp outside of official buildings, including the police...

Reforestation is such an urgent need and given that monoculture is so widespread (where I come from they replaced long ago a lot of the native broad leaf trees such as oak, sweet chestnut, ash and hazel with eucalyptus because it provided fast growing lumber for the paper industry locally) I wonder if this would be a way to return diversity to hard to reach monocultivated areas. Alas it is never so easy and even mature woodlands require careful management to provide the adequate balance of species and biodiversity.... Good way to start in remore areas with no tree cover though... Anything is better than nothing at this point.