Really annoys me when people don't come back too remove them after a few yrs & they litter the place looking untidy, & also sometimes the trees grows into them & they damage the trunk etc.   Could they not make them out of  biodegrable material?   Had a google & couldn't find any biodegradable ones for sale. Some are marketed as eco ones  say that the plastic had less UV stabalizer in them so they break into bits faster, which sounds worse than the normal ones