The wealth of any ecosystem is its perennials. The primal herbivore-predator-disturbance-rest dance is literally the breath and pulse of the earth. Grasses recycle oxygen far more efficiently than trees. The turnover is faster. Grass reaches out and turns solar energy into carbon. Tillage hyper-aerates the soil, burning out carbon. But because a plant creates bilateral symmetry at the soil horizon, it sloughs off root mass when the top gets chopped off.
Isn't it sad that you can tell people that the ozone layer is being depleted, the forests are being cut down, the deserts are advancing steadily, that the greenhouse effect will raise the sea level 200 feet, that overpopulation is choking us, that pollution is killing us, that nuclear war may destroy us - and they yawn and settle back for a comfortable nap. But tell them that the Martians are landing, and they scream and run.