Bill Mollison wrote in the Designer Handbook " Everything gardens " and produces conditions in the ecosystem favorable to themselves . Rabbits grow thistles , cattle grow grasses . With that in mind I would have to agree that wooly mammoths created favorable conditions for themselves . Read the article and see if you agree :
That reminded me of the way elephants and acacias interact, as portrayed in The Private Life of Plants (sorry, couldn't embed as it's not youtube)
Also, because it's nearly Valentine's day and everyone loves chocolate, here's a very special edition of The Magic School Bus which was my son's first introduction to ecology, many moons ago . Enjoy.