Gravity tends to pull fertility downhill. Hence fertile valleys and infertile hilltops. But wait, many times the most fertile soils are on hilltops. How could that be? Herbivores graze in the fertile valleys and then trudge up to the hilltops to chew their cuds and lounge. Why the hilltop? To watch for those nasty predators. The herbivore-grass, predator-prey relationships are foundational to moving those biomass-stored sunbeams around on the landscape. Without animals, the anti-gravitational movement would be impossible. Without the predator, it wouldn't be incentivized. Truly, this whole ecosystem is fearfully and wonderfully made.